A model for technology assessment applied to pulse oximetry. The Technology Assessment Task Force of the Society of Critical Care Medicine.

PubMed

1993-04-01

To test a model for the assessment of critical care technology. To develop practice guidelines for the use of pulse oximetry. A computer-assisted search of the English language literature and interviews with recognized experts in the field of pulse oximetry. Those studies that addressed one or more of the seven questions contained in our technology assessment template were analyzed. Study design was not a factor in article selection. However, the lack of well-designed clinical outcome studies was an important factor in determining the method of practice policy development we utilized. A focus person summarized the data from the selected studies that related to each of the seven assessment questions. The preliminary data summary developed by the focus person was further analyzed and refined by the task force and then sent to 16 expert reviewers for comment. These expert comments were considered by the task force, and this final consensus report was developed. Pulse oximetry combines the principles of spectrophotometry and plethysmography to noninvasively measure oxygen saturation with a high degree of accuracy over the range of 80% to 100% saturation, assuming the device is being used according to the manufacturer's instructions and without any adverse operating conditions. The appropriate clinical uses of pulse oximetry fall into one of two broad categories: as a warning system based on continuous real-time measurement of arterial desaturation, or as an end-point for titration of therapeutic interventions. There are no published studies that allow for definitive, outcome-based conclusions concerning either the clinical impact or cost-benefit ratio of pulse oximetry. The model developed for technology assessment proved to be appropriate for assessing pulse oximetry. The available data have allowed us to develop an evidence-based practice policy for the use of pulse oximetry in critical care. Critical care clinicians, researchers, and industry have a shared responsibility to provide valid outcome and efficacy studies of new technologies.

Pulse oximetry: fundamentals and technology update.

PubMed

Nitzan, Meir; Romem, Ayal; Koppel, Robert

2014-01-01

Oxygen saturation in the arterial blood (SaO2) provides information on the adequacy of respiratory function. SaO2 can be assessed noninvasively by pulse oximetry, which is based on photoplethysmographic pulses in two wavelengths, generally in the red and infrared regions. The calibration of the measured photoplethysmographic signals is performed empirically for each type of commercial pulse-oximeter sensor, utilizing in vitro measurement of SaO2 in extracted arterial blood by means of co-oximetry. Due to the discrepancy between the measurement of SaO2 by pulse oximetry and the invasive technique, the former is denoted as SpO2. Manufacturers of pulse oximeters generally claim an accuracy of 2%, evaluated by the standard deviation (SD) of the differences between SpO2 and SaO2, measured simultaneously in healthy subjects. However, an SD of 2% reflects an expected error of 4% (two SDs) or more in 5% of the examinations, which is in accordance with an error of 3%-4%, reported in clinical studies. This level of accuracy is sufficient for the detection of a significant decline in respiratory function in patients, and pulse oximetry has been accepted as a reliable technique for that purpose. The accuracy of SpO2 measurement is insufficient in several situations, such as critically ill patients receiving supplemental oxygen, and can be hazardous if it leads to elevated values of oxygen partial pressure in blood. In particular, preterm newborns are vulnerable to retinopathy of prematurity induced by high oxygen concentration in the blood. The low accuracy of SpO2 measurement in critically ill patients and newborns can be attributed to the empirical calibration process, which is performed on healthy volunteers. Other limitations of pulse oximetry include the presence of dyshemoglobins, which has been addressed by multiwavelength pulse oximetry, as well as low perfusion and motion artifacts that are partially rectified by sophisticated algorithms and also by reflection pulse oximetry.

Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia

DTIC Science & Technology

2015-10-01

eyes and image choroidal vessels/capillaries using CARS intravital microscopy Subtask 3: Measure oxy-hemoglobin levels in PBI test and control eyes...AWARD NUMBER: W81XWH-14-1-0537 TITLE: Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia...4. TITLE AND SUBTITLE Mobile, Multimodal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia 5a. CONTRACT NUMBER W81XWH

Accuracy of pulse oximetry in assessing heart rate of infants in the neonatal intensive care unit.

PubMed

Singh, Jasbir K S B; Kamlin, C Omar F; Morley, Colin J; O'Donnell, Colm P F; Donath, Susan M; Davis, Peter G

2008-05-01

To determine the accuracy of pulse oximetry measurement of heart rate in the neonatal intensive care unit. Stable preterm infants were monitored with a pulse oximeter and an ECG. The displays of both monitors were captured on video. Heart rate data from both monitors, including measures of signal quality, were extracted and analysed using Bland Altman plots. In 30 infants the mean (SD) difference between heart rate measured by pulse oximetry and electrocardiography was -0.4 (12) beats per minute. Accuracy was maintained when the signal quality or perfusion was low. Pulse oximetry may provide a useful measurement of heart rate in the neonatal intensive care unit. Studies of this technique in the delivery room are indicated.

Accuracy of noninvasive haemoglobin measurement by pulse oximetry depends on the type of infusion fluid.

PubMed

Bergek, Christian; Zdolsek, Joachim H; Hahn, Robert G

2012-12-01

Measurement of blood haemoglobin concentration by pulse oximetry could be of value in determining when erythrocytes should be transfused during surgery, but the effect of infusion fluids on the results is unclear. To study the effect of crystalloid and colloid fluid on the accuracy (bias) and precision of pulse oximetry haemoglobin estimation to indicate the venous haemoglobin concentration in volunteers. Open interventional crossover study. Single university hospital. Ten male volunteers aged 18-28 (mean 22) years. Each volunteer underwent three infusion experiments on separate days and in random order. The infusions were Ringer's acetate (20 ml kg), hydroxyethyl starch 130/0.4 (10 ml kg) and a combination of both. At the end of the infusions of Ringer's acetate, pulse oximetry haemoglobin concentration had decreased more than the true haemoglobin concentration (15 vs. 8%; P < 0.005; n = 10) whereas starch solution decreased pulse oximetry haemoglobin concentration less than true haemoglobin concentration (7 vs. 11%; P < 0.02; n = 20). The same differences were seen when the fluids were infused separately and when they were combined. The overall difference between all 956 pairs of pulse oximetry haemoglobin concentration and true haemoglobin concentrations (the bias) averaged only -0.7 g l whereas the 95% prediction interval was wide, ranging from -24.9 to 23.7 g l. In addition to the choice of infusion fluid, the bias was strongly dependent on the volunteer (each factor, P < 0.001). The bias of measuring haemoglobin concentration by pulse oximetry is dependent on whether a crystalloid or a colloid fluid is infused. Trial registration ClinicalTrials identifier: NCT01195025.

Feasibility and accuracy of nasal alar pulse oximetry.

PubMed

Morey, T E; Rice, M J; Vasilopoulos, T; Dennis, D M; Melker, R J

2014-06-01

The nasal ala is an attractive site for pulse oximetry because of perfusion by branches of the external and internal carotid arteries. We evaluated the accuracy of a novel pulse oximetry sensor custom designed for the nasal ala. After IRB approval, healthy non-smoking subjects [n=12; aged 28 (23-41) yr; 6M/6F] breathed hypoxic mixtures of fresh gas by a facemask to achieve oxyhaemoglobin saturations of 70-100% measured by traditional co-oximetry from radial artery samples. Concurrent alar and finger pulse oximetry values were measured using probes designed for these sites. Data were analysed using the Bland-Altman method for multiple observations per subject. Bias, precision, and accuracy root mean square error (ARMS) over a range of 70-100% were significantly better for the alar probe compared with a standard finger probe. The mean bias for the alar and finger probes was 0.73% and 1.90% (P<0.001), respectively, with corresponding precision values of 1.65 and 1.83 (P=0.015) and ARMS values of 1.78% and 2.72% (P=0.047). The coefficients of determination were 0.96 and 0.96 for the alar and finger probes, respectively. The within/between-subject variation for the alar and finger probes were 1.14/1.57% and 1.87/1.47%, respectively. The limits of agreement were 3.96/-2.50% and 5.48/-1.68% for the alar and finger probes, respectively. Nasal alar pulse oximetry is feasible and demonstrates accurate pulse oximetry values over a range of 70-100%. The alar probe demonstrated greater accuracy compared with a conventional finger pulse oximeter. © The Author [2014]. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Evaluation of Masimo signal extraction technology pulse oximetry in anaesthetized pregnant sheep.

PubMed

Quinn, Christopher T; Raisis, Anthea L; Musk, Gabrielle C

2013-03-01

Evaluation of the accuracy of Masimo signal extraction technology (SET) pulse oximetry in anaesthetized late gestational pregnant sheep. Prospective experimental study. Seventeen pregnant Merino ewes. Animals included in study were late gestation ewes undergoing general anaesthesia for Caesarean delivery or foetal surgery in a medical research laboratory. Masimo Radical-7 pulse oximetry (SpO(2) ) measurements were compared to co-oximetry (SaO(2) ) measurements from arterial blood gas analyses. The failure rate of the pulse oximeter was calculated. Accuracy was assessed by Bland & Altman's (2007) limits of agreement method. The effect of mean arterial blood pressure (MAP), perfusion index (PI) and haemoglobin (Hb) concentration on accuracy were assessed by regression analysis. Forty arterial blood samples paired with SpO(2) and blood pressure measurements were obtained. SpO(2) ranged from 42 to 99% and SaO(2) from 43.7 to 99.9%. MAP ranged from 24 to 82 mmHg, PI from 0.1 to 1.56 and Hb concentration from 71 to 114 g L(-1) . Masimo pulse oximetry measurements tended to underestimate oxyhaemoglobin saturation compared to co-oximetry with a bias (mean difference) of -2% and precision (standard deviation of the differences) of 6%. Accuracy appeared to decrease when SpO(2) was <75%, however numbers were too small for statistical comparisons. Hb concentration and PI had no significant effect on accuracy, whereas MAP was negatively correlated with SpO(2) bias. Masimo SET pulse oximetry can provide reliable and continuous monitoring of arterial oxyhaemoglobin saturation in anaesthetized pregnant sheep during clinically relevant levels of cardiopulmonary dysfunction. Further work is needed to assess pulse oximeter function during extreme hypotension and hypoxaemia. © 2012 The Authors. Veterinary Anaesthesia and Analgesia. © 2012 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesiologists.

Texas Pulse Oximetry Project: A Multicenter Educational and Quality Improvement Project for Implementation of Critical Congenital Heart Disease Screening Using Pulse Oximetry.

PubMed

Guillory, Charleta; Gong, Alice; Livingston, Judith; Creel, Liza; Ocampo, Elena; McKee-Garrett, Tiffany

2017-07-01

Objective  Critical congenital heart disease (CCHD) is a leading cause of death in infants. Newborn screening (NBS) by pulse oximetry allows early identification of CCHD in asymptomatic newborns. To improve readiness of hospital neonatal birthing facilities for mandatory screening in Texas, an educational and quality improvement (QI) project was piloted to identify an implementation strategy for CCHD NBS in a range of birthing hospitals. Study Design  Thirteen Texas hospitals implemented standardized CCHD screening by pulse oximetry. An educational program was devised and a tool kit was created to facilitate education and implementation. Newborn nursery nurses' knowledge was assessed using a pre- and posttest instrument. Results  The nurses' knowledge assessment improved from 71 to 92.5% ( p  < 0.0001). Of 11,322 asymptomatic newborns screened after 24 hours of age, 11 had a positive screen, with 1 confirmed case of CCHD. Pulse oximetry CCHD NBS had sensitivity of 100%, specificity of 99.91%, false-positive rate of 0.088%, positive predictive value of 9.09%, and negative predictive value of 100%. Conclusion  Our educational program, including a tool kit, QI processes, and standardized pulse oximetry CCHD NBS, is applicable for a range of hospital birthing facilities and may facilitate wide-scale implementation, thereby improving newborn health. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

The Accuracy of Noninvasive Peripheral Pulse Oximetry After Palliative Cardiac Surgery in Patients With Cyanotic Congenital Heart Disease.

PubMed

Scrimgeour, Gemma E; Griksaitis, Michael J; Pappachan, John V; Baldock, Andrew J

2017-01-01

Children with cyanotic congenital heart disease (CCHD) live with oxyhemoglobin saturations that are typically expressed as percentages in the range of 70s and 80s. Peripheral pulse oximetry (measurement of SpO 2 ) performs poorly in this range and yet is widely used to inform clinical decisions in these patients. The reference standard is co-oximetry of arterial samples (SaO 2 ). In this study, 515 paired measurements of SpO 2 and SaO 2 were taken from 19 children who had undergone palliative cardiac surgery. SpO 2 (Masimo SET LNCS Neo pulse oximeter) overestimated oxyhemoglobin saturation in 82% of measurements (mean 4.6% ± 6.6%). There was a strong negative correlation between mean bias and SaO 2 ( r = -.96, P = .002, 95% confidence interval: -0.99 to -0.68). The results raise a concern that critical hypoxemia may go undetected and untreated if pulse oximetry is relied upon as the primary means of assessing oxyhemoglobin saturation in children with CCHD. Strong preference must be given to co-oximetry of arterial samples.

Pulse oximeter accuracy and precision at five different sensor locations in infants and children with cyanotic heart disease.

PubMed

Das, Jyotirmoy; Aggarwal, Amit; Aggarwal, Naresh Kumar

2010-11-01

Since the invention of pulse oximetry by Takuo Aoyagi in the early 1970s, its use has expanded beyond the perioperative care into neonatal, paediatric and adult intensive care units (ICUs). Pulse oximetry is one of the most important advances in respiratory monitoring as its readings (SpO(2)) are used clinically as an indirect estimation of arterial oxygen saturation (SaO(2)). Sensors were placed frequently on the sole, palm, ear lobe or toes in addition to finger. On performing an extensive Medline search using the terms "accuracy of pulse oximetry" and "precision of pulse oximetry", limited data were found in congenital heart disease patients in the immediate post-corrective stage. Also, there are no reports and comparative data of the reliability and precision of pulse oximetry when readings from five different sensor locations (viz. finger, palm, toe, sole and ear) are analysed simultaneously. To fill these lacunae of knowledge, we undertook the present study in 50 infants and children with cyanotic heart disease in the immediate post-corrective stage.

Can we Replace Arterial Blood Gas Analysis by Pulse Oximetry in Neonates with Respiratory Distress Syndrome, who are Treated According to INSURE Protocol?

PubMed Central

Niknafs, Pedram; Norouzi, Elahe; Bahman Bijari, Bahareh; Baneshi, Mohammad Reza

2015-01-01

Neonates with respiratory distress syndrome (RDS), who are treated according to INSURE protocol; require arterial blood gas (ABG) analysis to decide on appropriate management. We conducted this study to investigate the validity of pulse oximetry instead of frequent ABG analysis in the evaluation of these patients. From a total of 193 blood samples obtained from 30 neonates <1500 grams with RDS, 7.2% were found to have one or more of the followings: acidosis, hypercapnia, or hypoxemia. We found that pulse oximetry in the detection of hyperoxemia had a good validity to appropriately manage patients without blood gas analysis. However, the validity of pulse oximetry was not good enough to detect acidosis, hypercapnia, and hypoxemia. PMID:25999627

A probe for blood-vessel and spinal interiors

NASA Technical Reports Server (NTRS)

Frazer, R. E.

1978-01-01

Probe design allows insertion into lumen of blood vessels to perform oximetry and investigate plaque on interior vessel walls. Probe is more accurate than standard oximetry procedures of determining oxygenation of circulating blood.

Minimally invasive optical biopsy for oximetry

NASA Astrophysics Data System (ADS)

van der Putten, Marieke A.; Brewer, James M.; Harvey, Andrew R.

2017-02-01

The study of localised oxygen saturation in blood vessels can shed light on the etiology and progression of many diseases with which hypoxia is associated. For example, hypoxia in the tendon has been linked to early stages of rheumatoid arthritis, an auto-immune inflammatory disease. Vascular oximetry of deep tissue presents significant challenges as vessels are not optically accessible. In this paper, we present a novel multispectral imaging technique for vascular oximetry, and recent developments made towards its adaptation for minimally invasive imaging. We present proof-of-concept of the system and illumination scheme as well as the analysis technique. We present results of a validation study performed in vivo on mice with acutely inflamed tendons. Adaptation of the technique for minimally invasive microendoscopy is also presented, along with preliminary results of minimally invasive ex vivo vascular oximetry.

Comparative Evaluation of Accuracy of Pulse Oximeters and Factors Affecting Their Performance in a Tertiary Intensive Care Unit

PubMed Central

Sahi, Malvinder Singh; Mahawar, Bablesh; Rajpurohit, Sajjan

2017-01-01

Introduction Pulse oximetry is a widely used tool, unfortunately there is a paucity of data investigating its accuracy in Intensive Care Units (ICU) and if they are able to meet mandated FDA criteria as claimed by them in critically ill patients. Aim To assess bias, precision and accuracy of pulse oximeters used in ICU and factors affecting them. Materials and Methods A prospective cohort study, including 129 patients admitted to the ICU of a tertiary referral centre. Pulse oximetry and blood gas were done simultaneously. Pulse oximetry was done using two pulse oximetres: Nonin and Philips. All physiological variables like haemoglobin, lactate, use of vasopressors and blood pressure were recorded. Bland Altman curves were constructed to determine bias and limits of agreement. Effect of physiological variables on bias and difference between performance characteristics of bias was determined using SPSS. Results Pulse oximetry overestimated arterial oxygen saturation (SaO2) by 1.44%. There was negative correlation between bias and SaO2 (r=-0.32) and positive correlation with lactate (r=0.16). The Philips pulse oximeter had significant higher bias and variability than Nonin pulse oximeter. (2.49±2.99 versus 0.46±1.68, mean difference = 1.98, 95% C.I. = 1.53 – 2.43, p-value <0.001). Conclusion Pulse oximetry overestimates SaO2. Bias tends to increase with rising lactate and hypoxia. There is heterogeneity in performance of various pulse oximetry devices in ICU. PMID:28764215

Comparative Evaluation of Accuracy of Pulse Oximeters and Factors Affecting Their Performance in a Tertiary Intensive Care Unit.

PubMed

Singh, Anupam Kumar; Sahi, Malvinder Singh; Mahawar, Bablesh; Rajpurohit, Sajjan

2017-06-01

Pulse oximetry is a widely used tool, unfortunately there is a paucity of data investigating its accuracy in Intensive Care Units (ICU) and if they are able to meet mandated FDA criteria as claimed by them in critically ill patients. To assess bias, precision and accuracy of pulse oximeters used in ICU and factors affecting them. A prospective cohort study, including 129 patients admitted to the ICU of a tertiary referral centre. Pulse oximetry and blood gas were done simultaneously. Pulse oximetry was done using two pulse oximetres: Nonin and Philips. All physiological variables like haemoglobin, lactate, use of vasopressors and blood pressure were recorded. Bland Altman curves were constructed to determine bias and limits of agreement. Effect of physiological variables on bias and difference between performance characteristics of bias was determined using SPSS. Pulse oximetry overestimated arterial oxygen saturation (SaO 2 ) by 1.44%. There was negative correlation between bias and SaO 2 (r=-0.32) and positive correlation with lactate (r=0.16). The Philips pulse oximeter had significant higher bias and variability than Nonin pulse oximeter. (2.49±2.99 versus 0.46±1.68, mean difference = 1.98, 95% C.I. = 1.53 - 2.43, p-value <0.001). Pulse oximetry overestimates SaO 2 . Bias tends to increase with rising lactate and hypoxia. There is heterogeneity in performance of various pulse oximetry devices in ICU.

A Comparative Evaluation of EPR and OxyLite Oximetry Using a Random Sampling of pO2 in a Murine Tumor

PubMed Central

Vikram, Deepti S.; Bratasz, Anna; Ahmad, Rizwan; Kuppusamy, Periannan

2015-01-01

Methods currently available for the measurement of oxygen concentrations (oximetry) in viable tissues differ widely from each other in their methodological basis and applicability. The goal of this study was to compare two novel methods, particulate-based electron paramagnetic resonance (EPR) and OxyLite oximetry, in an experimental tumor model. EPR oximetry uses implantable paramagnetic particulates, whereas OxyLite uses fluorescent probes affixed on a fiber-optic cable. C3H mice were transplanted with radiation-induced fibrosarcoma (RIF-1) tumors in their hind limbs. Lithium phthalocyanine (LiPc) microcrystals were used as EPR probes. The pO2 measurements were taken from random locations at a depth of ~3 mm within the tumor either immediately or 48 h after implantation of LiPc. Both methods revealed significant hypoxia in the tumor. However, there were striking differences between the EPR and OxyLite readings. The differences were attributed to the volume of tissue under examination and the effect of needle invasion at the site of measurement. This study recognizes the unique benefits of EPR oximetry in terms of robustness, repeatability and minimal invasiveness. PMID:17705635

Quantitative evaluation of photoplethysmographic artifact reduction for pulse oximetry

NASA Astrophysics Data System (ADS)

Hayes, Matthew J.; Smith, Peter R.

1999-01-01

Motion artefact corruption of pulse oximeter output, causing both measurement inaccuracies and false alarm conditions, is a primary restriction in the current clinical practice and future applications of this useful technique. Artefact reduction in photoplethysmography (PPG), and therefore by application in pulse oximetry, is demonstrated using a novel non-linear methodology recently proposed by the authors. The significance of these processed PPG signals for pulse oximetry measurement is discussed, with particular attention to the normalization inherent in the artefact reduction process. Quantitative experimental investigation of the performance of PPG artefact reduction is then utilized to evaluate this technology for application to pulse oximetry. While the successfully demonstrated reduction of severe artefacts may widen the applicability of all PPG technologies and decrease the occurrence of pulse oximeter false alarms, the observed reduction of slight artefacts suggests that many such effects may go unnoticed in clinical practice. The signal processing and output averaging used in most commercial oximeters can incorporate these artefact errors into the output, while masking the true PPG signal corruption. It is therefore suggested that PPG artefact reduction should be incorporated into conventional pulse oximetry measurement, even in the absence of end-user artefact problems.

Prognostic value of nocturnal pulse oximetry in patients with heart failure.

PubMed

Rivera-López, Ricardo; Jordán-Martínez, Laura; López-Fernández, Silvia; Rivera-Fernandez, Ricardo; Tercedor, Luis; Sáez-Roca, Germán

2018-05-23

To analyze the prognostic value of nocturnal hypoxemia measured with portable nocturnal pulse-oximetry in patients hospitalized due to heart failure and its relation to mortality and hospital readmission. We included 38 patients who were admitted consecutively to our unit with the diagnosis of decompensated heart failure. Pulse-oximetry was considered positive for hypoxemia when more than 10 desaturations per hour were recorded during sleep. Follow-up was performed for 30.3 (standard deviation [SD] 14.2) months, the main objective being a combined endpoint of all-cause mortality and hospital readmission due to heart failure. The average age was 70.7 (SD 10.7) years, 63.3% were males. Pulse-oximetry was considered positive for hypoxemia in 27 (71%) patients. Patients with positive pulse-oximetry had the most frequent endpoint (9.1% [1] vs. 61.5% [16], P = 0.003). After multivariate analysis, continuous nocturnal hypoxemia was related to the combined endpoint (HR = 8.37, 1.19-68.4, P = 0.03). Patients hospitalized for heart failure and nocturnal hypoxemia measured with portable pulse-oximeter have an increased risk of hospital readmission and death. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Pulse oximetry screening in Wisconsin.

PubMed

Beissel, Daniel J; Goetz, Elizabeth M; Hokanson, John S

2012-01-01

Pulse oximetry can be used as a screening tool to detect critical congenital heart disease (CCHD) in neonates prior to hospital discharge and the development of symptoms. Newborns suspected of having CCHD based on pulse oximetry screening should have the diagnosis excluded or confirmed with echocardiography. However, echocardiography is not immediately available in all settings in which newborns are delivered and the best course of action in these settings remains to be determined. The purpose of this study was to evaluate the resources available to diagnose and treat newborns with CCHD born in the state of Wisconsin. We surveyed the nurse managers or administrators of the 99 Wisconsin hospitals in which babies are routinely delivered in the state of Wisconsin. A telephone survey was performed in February and March 2011. The number of births per facility was estimated from the most recent available data (2010). There were 66 179 total births occurring in 106 hospitals in the state of Wisconsin in 2010, with 99 hospitals routinely delivering newborns. Surveys were completed in 88/99 (88.9%), representing 95% of the state's in-hospital births. All responding hospitals had pulse oximetry available in the nursery. Twenty-five of 88 (28.4%) of responding hospitals routinely use pulse oximetry to screen for CCHD, representing 35.2% of surveyed hospital births. Same-day neonatal echocardiography was available at 33/88 (37.5%) of the responding hospitals, representing 74.4% of surveyed hospital births. The average distance to the higher-level care facility of choice from the hospitals without neonatal echocardiography is 53.1 miles. Pulse oximetry is universally available in Wisconsin newborn nurseries, and pulse oximetry screening for CCHD is currently being performed for many of Wisconsin's newborns. The majority of births in Wisconsin occur in hospitals where same-day neonatal echocardiography is available for confirmatory diagnosis of CCHD when necessary. © 2012 Wiley Periodicals, Inc.

Simultaneous use of intrapartum fetal pulse oximetry and amnioinfusion in meconium stained amniotic fluid.

PubMed

Halvax, László; Szabó, István; Vizer, Miklós; Csermely, Tamás; Ertl, Tibor

2002-09-10

Fetal pulse oximetry is a minimally invasive, simple technique which continuously helps to reflect in utero well-being. The presence of meconium in the amniotic fluid may be a clinical sign of fetal hypoxaemia. Amnioinfusion has a beneficial effect on the incidence of meconium aspiration syndrome (MAS), and the presence of meconium below the level of the vocal cords. We studied the impact of amnioinfusion combined with fetal pulse oximetry on the incidence of meconium aspiration syndrome and operative delivery. The retrospective analysis revealed that the presence of meconium below the level of vocal cords was significantly reduced. The frequency of cesarean section is decreased, however, it did not reach statistical significance. Fetal pulse oximetry may be used in combination with amnioinfusion and cardiotocography (CTG) to reduce the risk of meconium aspiration syndrome and the number of instrumental deliveries and improve perinatal outcome. Copyright 2002 Elsevier Science Ireland Ltd.

Influence of sleep-disordered breathing assessed by pulse oximetry on long-term clinical outcomes in patients who underwent percutaneous coronary intervention.

PubMed

Yatsu, Shoichiro; Naito, Ryo; Kasai, Takatoshi; Matsumoto, Hiroki; Shitara, Jun; Shimizu, Megumi; Murata, Azusa; Kato, Takao; Suda, Shoko; Hiki, Masaru; Sai, Eiryu; Miyauchi, Katsumi; Daida, Hiroyuki

2018-03-31

Sleep-disordered breathing (SDB) has been recognized as an important risk factor for coronary artery disease (CAD). However, SDB was not fully examined, because sleep studies are limited. Nocturnal pulse oximetry has been suggested to be a useful tool for evaluating SDB. Therefore, the aim of this study was to investigate the influence of SDB assessed by nocturnal pulse oximetry on clinical outcomes in patients who underwent percutaneous coronary intervention (PCI). We conducted a prospective, multicenter, observational cohort study, wherein SDB was assessed by finger pulse oximetry in patients who underwent PCI from January 2014 to December 2016. SDB was defined as 4% oxygen desaturation index of 5 and higher. The primary endpoint was major adverse cardiac or cerebrovascular event (MACCE), defined as a composite of all-cause mortality, acute coronary syndrome, and/or stroke. Of 539 patients, 296 (54.9%) had SDB. MACCE occurred in 32 patients (5.8%) during a median follow-up of 1.9 years. The cumulative incidence of MACCE was significantly higher in patients with SDB (P = 0.0134). In the stepwise multivariable Cox proportional model, the presence of SDB was a significant predictor of MACCE (hazard ratio 2.26; 95% confidence interval 1.05-5.4, P = 0.036). SDB determined by nocturnal pulse oximetry was associated with worse clinical outcomes in patients who underwent PCI. Screening for SDB with nocturnal pulse oximetry was considered to be important for risk stratification in patients with CAD.

Performance evaluation of photoacoustic oximetry imaging systems using a dynamic blood flow phantom with tunable oxygen saturation

NASA Astrophysics Data System (ADS)

Vogt, William C.; Zhou, Xuewen; Andriani, Rudy; Wear, Keith A.; Garra, Brian S.; Pfefer, Joshua

2018-02-01

Photoacoustic Imaging (PAI) is an emerging technology with strong potential for broad clinical applications from breast cancer detection to cerebral monitoring due to its ability to compute maps of blood oxygen saturation (SO2) distribution in deep tissues using multispectral imaging. However, no well-validated consensus test methods currently exist for evaluating oximetry-specific performance characteristics of PAI devices. We have developed a phantombased flow system capable of rapid SO2 adjustment to serve as a test bed for elucidation of factors impacting SO2 measurement and quantitative characterization of device performance. The flow system is comprised of a peristaltic pump, membrane oxygenator, oxygen and nitrogen gas, and in-line oxygen, pH, and temperature sensors that enable real-time estimation of SO2 reference values. Bovine blood was delivered through breast-relevant tissue phantoms containing vessel-mimicking fluid channels, which were imaged using a custom multispectral PAI system. Blood was periodically drawn for SO2 measurement in a clinical-grade CO-oximeter. We used this flow phantom system to evaluate the impact of device parameters (e.g.,wavelength-dependent fluence corrections) and tissue parameters (e.g. fluid channel depth, blood SO2, spectral coloring artifacts) on oximetry measurement accuracy. Results elucidated key challenges in PAI oximetry and device design trade-offs, which subsequently allowed for optimization of system performance. This approach provides a robust benchtop test platform that can support PAI oximetry device optimization, performance validation, and clinical translation, and may inform future development of consensus test methods for performance assessment of photoacoustic oximetry imaging systems.

Classification methods to detect sleep apnea in adults based on respiratory and oximetry signals: a systematic review.

PubMed

Uddin, M B; Chow, C M; Su, S W

2018-03-26

Sleep apnea (SA), a common sleep disorder, can significantly decrease the quality of life, and is closely associated with major health risks such as cardiovascular disease, sudden death, depression, and hypertension. The normal diagnostic process of SA using polysomnography is costly and time consuming. In addition, the accuracy of different classification methods to detect SA varies with the use of different physiological signals. If an effective, reliable, and accurate classification method is developed, then the diagnosis of SA and its associated treatment will be time-efficient and economical. This study aims to systematically review the literature and present an overview of classification methods to detect SA using respiratory and oximetry signals and address the automated detection approach. Sixty-two included studies revealed the application of single and multiple signals (respiratory and oximetry) for the diagnosis of SA. Both airflow and oxygen saturation signals alone were effective in detecting SA in the case of binary decision-making, whereas multiple signals were good for multi-class detection. In addition, some machine learning methods were superior to the other classification methods for SA detection using respiratory and oximetry signals. To deal with the respiratory and oximetry signals, a good choice of classification method as well as the consideration of associated factors would result in high accuracy in the detection of SA. An accurate classification method should provide a high detection rate with an automated (independent of human action) analysis of respiratory and oximetry signals. Future high-quality automated studies using large samples of data from multiple patient groups or record batches are recommended.

Assessment of automated analysis of portable oximetry as a screening test for moderate-to-severe sleep apnea in patients with chronic obstructive pulmonary disease

PubMed Central

Andrés-Blanco, Ana M.; Álvarez, Daniel; Crespo, Andrea; Arroyo, C. Ainhoa; Cerezo-Hernández, Ana; Gutiérrez-Tobal, Gonzalo C.; Hornero, Roberto

2017-01-01

Background The coexistence of obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD) leads to increased morbidity and mortality. The development of home-based screening tests is essential to expedite diagnosis. Nevertheless, there is still very limited evidence on the effectiveness of portable monitoring to diagnose OSAS in patients with pulmonary comorbidities. Objective To assess the influence of suffering from COPD in the performance of an oximetry-based screening test for moderate-to-severe OSAS, both in the hospital and at home. Methods A total of 407 patients showing moderate-to-high clinical suspicion of OSAS were involved in the study. All subjects underwent (i) supervised portable oximetry simultaneously to in-hospital polysomnography (PSG) and (ii) unsupervised portable oximetry at home. A regression-based multilayer perceptron (MLP) artificial neural network (ANN) was trained to estimate the apnea-hypopnea index (AHI) from portable oximetry recordings. Two independent validation datasets were analyzed: COPD versus non-COPD. Results The portable oximetry-based MLP ANN reached similar intra-class correlation coefficient (ICC) values between the estimated AHI and the actual AHI for the non-COPD and the COPD groups either in the hospital (non-COPD: 0.937, 0.909–0.956 CI95%; COPD: 0.936, 0.899–0.960 CI95%) and at home (non-COPD: 0.731, 0.631–0.808 CI95%; COPD: 0.788, 0.678–0.864 CI95%). Regarding the area under the receiver operating characteristics curve (AUC), no statistically significant differences (p >0.01) between COPD and non-COPD groups were found in both settings, particularly for severe OSAS (AHI ≥30 events/h): 0.97 (0.92–0.99 CI95%) non-COPD vs. 0.98 (0.92–1.0 CI95%) COPD in the hospital, and 0.87 (0.79–0.92 CI95%) non-COPD vs. 0.86 (0.75–0.93 CI95%) COPD at home. Conclusion The agreement and the diagnostic performance of the estimated AHI from automated analysis of portable oximetry were similar regardless of the presence of COPD both in-lab and at-home. Particularly, portable oximetry could be used as an abbreviated screening test for moderate-to-severe OSAS in patients with COPD. PMID:29176802

Retinal oximetry measures systemic hypoxia in central nervous system vessels in chronic obstructive pulmonary disease

PubMed Central

Bragason, David; Hardarson, Sveinn Hakon; Vacchiano, Charles; Gislason, Thorarinn; Kristjansdottir, Jona Valgerdur; Kristjansdottir, Gudrun; Stefánsson, Einar

2017-01-01

Background Determination of the blood oxyhemoglobin saturation in the retinal vessels of the eye can be achieved through spectrophotometric retinal oximetry which provides access to the state of oxyhemoglobin saturation in the central nervous system circulation. The purpose of this study was to test the capability of the Oxymap T1 oximeter to detect systemic hypoxemia and the effect of supplemental oxygen on retinal vessel oxyhemoglobin saturation. Methods Oxygen saturation of hemoglobin in retinal arterioles and venules was measured in 11 subjects with severe chronic obstructive pulmonary disease (COPD) on long term oxygen therapy. Measurements were made with and without their daily supplemental oxygen. Eleven healthy age and gender matched subjects were measured during ambient air breathing for comparison of oxyhemoglobin saturation in retinal arterioles and venules. Retinal arteriolar oxyhemoglobin saturation in COPD subjects inspiring ambient air was compared with finger pulse oximetry and blood samples from radial artery. Results COPD subjects had significantly lower oxyhemoglobin saturation during ambient air breathing than healthy controls in both retinal arterioles (87.2%±4.9% vs. 93.4%±4.3%, p = 0.02; n = 11) and venules (45.0%±10.3% vs. 55.2%±5.5%, p = 0.01). Administration of their prescribed supplemental oxygen increased oxyhemoglobin saturation in retinal arterioles (87.2%±4.9% to 89.5%±6.0%, p = 0.02) but not in venules (45.0%±10.3% to 46.7%±12.8%, p = 0.3). Retinal oximetry values were slightly lower than radial artery blood values (mean percentage points difference = -5.0±5.4, 95% CI: -15.68 to 5.67) and finger pulse oximetry values (-3.1±5.5, 95% CI: -14.05 to 7.84). Conclusions The noninvasive Oxymap T1 retinal oximetry detects hypoxemia in central nervous system vessels in patients with severe COPD compared with healthy controls. The instrument is sensitive to changes in oxygen breathing but displays slightly lower measures than finger pulse oximetry or radial artery measures. With further technological improvement, retinal oximetry may offer noninvasive “on-line” measurement of oxygen levels in central circulation in general anesthesia and critically ill patients. PMID:28328974

Assessment of automated analysis of portable oximetry as a screening test for moderate-to-severe sleep apnea in patients with chronic obstructive pulmonary disease.

PubMed

Andrés-Blanco, Ana M; Álvarez, Daniel; Crespo, Andrea; Arroyo, C Ainhoa; Cerezo-Hernández, Ana; Gutiérrez-Tobal, Gonzalo C; Hornero, Roberto; Del Campo, Félix

2017-01-01

The coexistence of obstructive sleep apnea syndrome (OSAS) and chronic obstructive pulmonary disease (COPD) leads to increased morbidity and mortality. The development of home-based screening tests is essential to expedite diagnosis. Nevertheless, there is still very limited evidence on the effectiveness of portable monitoring to diagnose OSAS in patients with pulmonary comorbidities. To assess the influence of suffering from COPD in the performance of an oximetry-based screening test for moderate-to-severe OSAS, both in the hospital and at home. A total of 407 patients showing moderate-to-high clinical suspicion of OSAS were involved in the study. All subjects underwent (i) supervised portable oximetry simultaneously to in-hospital polysomnography (PSG) and (ii) unsupervised portable oximetry at home. A regression-based multilayer perceptron (MLP) artificial neural network (ANN) was trained to estimate the apnea-hypopnea index (AHI) from portable oximetry recordings. Two independent validation datasets were analyzed: COPD versus non-COPD. The portable oximetry-based MLP ANN reached similar intra-class correlation coefficient (ICC) values between the estimated AHI and the actual AHI for the non-COPD and the COPD groups either in the hospital (non-COPD: 0.937, 0.909-0.956 CI95%; COPD: 0.936, 0.899-0.960 CI95%) and at home (non-COPD: 0.731, 0.631-0.808 CI95%; COPD: 0.788, 0.678-0.864 CI95%). Regarding the area under the receiver operating characteristics curve (AUC), no statistically significant differences (p >0.01) between COPD and non-COPD groups were found in both settings, particularly for severe OSAS (AHI ≥30 events/h): 0.97 (0.92-0.99 CI95%) non-COPD vs. 0.98 (0.92-1.0 CI95%) COPD in the hospital, and 0.87 (0.79-0.92 CI95%) non-COPD vs. 0.86 (0.75-0.93 CI95%) COPD at home. The agreement and the diagnostic performance of the estimated AHI from automated analysis of portable oximetry were similar regardless of the presence of COPD both in-lab and at-home. Particularly, portable oximetry could be used as an abbreviated screening test for moderate-to-severe OSAS in patients with COPD.

Beyond Critical Congenital Heart Disease: Newborn Screening Using Pulse Oximetry for Neonatal Sepsis and Respiratory Diseases in a Middle-Income Country.

PubMed

Jawin, Vida; Ang, Hak-Lee; Omar, Asma; Thong, Meow-Keong

2015-01-01

Studies on pulse oximetry screening for neonatal sepsis and respiratory disease in a middle-income country are lacking. Newborn screening for critical congenital heart disease (CCHD) using pulse oximetry is an effective and life-saving strategy in developed countries. While most studies have reported false-positive results during CCHD screening, they have not elaborated on the detected disease types. We studied the effectiveness and outcomes of pulse oximetry newborn screening for non-cardiac hypoxemic diseases such as neonatal sepsis, respiratory diseases, and CCHD in a middle-income country. In a pilot study performed at the University Malaya Medical Centre (UMMC), Malaysia, all apparently healthy term newborns, delivered at UMMC were screened pre-discharge using pulse oximetry. Echocardiography was performed for newborns that had positive screening results on two separate occasions, 1-h apart. Newborns with normal echocardiograms were evaluated and treated for other non-cardiac diseases. Fifteen of 5247 term newborns had positive screening results. The median age at screening was 20 h. Thirteen newborns (0.24%) had significant non-cardiac diseases: sepsis (n = 2) and respiratory diseases (n = 11) that required hospitalization and treatment. The remaining two newborns with normal antenatal ultrasonograms had positive screening test and confirmed to have CCHD. Another 18 newborns with negative screening test were later admitted for treatment of sepsis (n = 16) and penumonia (n = 2). All newborns were treated and alive at the end of the study. The sensitivity and specificity of pulse oximetry screening for non-cardiac diseases were 42% and 99.9% respectively, and 100% and 99.7% for CCHD, respectively. Routine pulse oximetry screening test was effective in identifying newborns with CCHD and other hypoxemia illnesses, which may led to potential life-threatening condition. This study showed that the expanded use of pulse oximetry has immediate implications for low- and middle-income countries contemplating strategies to reduce neonatal mortality and morbidity. ASD, atrial septal defect; CCHD, critical congenital heart disease; CRP, C-reactive protein; CXR, chest radiographs; NDI, neurodevelopment impairment; PPHN, persistent pulmonary hypertension of the newborn; PDA, patent ductus arteriosus; PFO, patent foramen ovale; TGA, transposition of great artery; TTN, transient tachypnoea of the newborn; VSD, ventricular septal defect.

Electron paramagnetic resonance oximetry as a quantitative method to measure cellular respiration: a consideration of oxygen diffusion interference.

PubMed

Presley, Tennille; Kuppusamy, Periannan; Zweier, Jay L; Ilangovan, Govindasamy

2006-12-15

Electron paramagnetic resonance (EPR) oximetry is being widely used to measure the oxygen consumption of cells, mitochondria, and submitochondrial particles. However, further improvement of this technique, in terms of data analysis, is required to use it as a quantitative tool. Here, we present a new approach for quantitative analysis of cellular respiration using EPR oximetry. The course of oxygen consumption by cells in suspension has been observed to have three distinct zones: pO(2)-independent respiration at higher pO(2) ranges, pO(2)-dependent respiration at low pO(2) ranges, and a static equilibrium with no change in pO(2) at very low pO(2) values. The approach here enables one to comprehensively analyze all of the three zones together-where the progression of O(2) diffusion zones around each cell, their overlap within time, and their potential impact on the measured pO(2) data are considered. The obtained results agree with previously established methods such as high-resolution respirometry measurements. Additionally, it is also demonstrated how the diffusion limitations can depend on cell density and consumption rate. In conclusion, the new approach establishes a more accurate and meaningful model to evaluate the EPR oximetry data on cellular respiration to quantify related parameters using EPR oximetry.

Repeated assessment of orthotopic glioma pO2 by multi-site EPR oximetry: A technique with the potential to guide therapeutic optimization by repeated measurements of oxygen

PubMed Central

Khan, Nadeem; Mupparaju, Sriram; Hou, Huagang; Williams, Benjamin B.; Swartz, Harold

2011-01-01

Tumor hypoxia plays a vital role in therapeutic resistance. Consequently, measurements of tumor pO2 could be used to optimize the outcome of oxygen-dependent therapies, such as, chemoradiation. However, the potential optimizations are restricted by the lack of methods to repeatedly and quantitatively assess tumor pO2 during therapies, particularly in gliomas. We describe the procedures for repeated measurements of orthotopic glioma pO2 by multi-site electron paramagnetic resonance (EPR) oximetry. This oximetry approach provides simultaneous measurements of pO2 at more than one site in the glioma and contralateral cerebral tissue. The pO2 of intracerebral 9L, C6, F98 and U251 tumors, as well as contralateral brain, were measured repeatedly for five consecutive days. The 9L glioma was well oxygenated with pO2 of 27 - 36 mm Hg, while C6, F98 and U251 glioma were hypoxic with pO2 of 7 - 12 mm Hg. The potential of multi-site EPR oximetry to assess temporal changes in tissue pO2 was investigated in rats breathing 100% O2. A significant increase in F98 tumor and contralateral brain pO2 was observed on day 1 and day 2, however, glioma oxygenation declined on subsequent days. In conclusion, EPR oximetry provides the capability to repeatedly assess temporal changes in orthotopic glioma pO2. This information could be used to test and optimize the methods being developed to modulate tumor hypoxia. Furthermore, EPR oximetry could be potentially used to enhance the outcome of chemoradiation by scheduling treatments at times of increase in glioma pO2. PMID:22079559

Pulse oximeter oxygen saturation in prediction of arterial oxygen saturation in liver transplant candidates.

PubMed

Ghayumi, Seiyed Mohammad Ali; Khalafi-Nezhad, Abolfazl; Jowkar, Zahra

2014-04-01

Liver transplant is the only definitive treatment for many patients with end stage liver disease. Presence and severity of preoperative pulmonary disease directly affect the rate of postoperative complications of the liver transplantation. Arterial blood gas (ABG) measurement, performed in many transplant centers, is considered as a traditional method to diagnose hypoxemia. Because ABG measurement is invasive and painful, pulse oximetry, a bedside, noninvasive and inexpensive technique, has been recommended as an alternative source for the ABG measurement. The aim of this study was to evaluate the efficacy of pulse oximetry as a screening tool in hypoxemia detection in liver transplant candidates and to compare the results with ABGs. Three hundred and ninety transplant candidates (237 males and 153 females) participated in this study. Arterial blood gas oxyhemoglobin saturation (SaO2) was recorded and compared with pulse oximetry oxyhemoglobin saturation (SpO2) results for each participants. The area under the curve (AUC) of receiver operating characteristic (ROC) curves was calculated by means of nonparametric methods to evaluate the efficacy of pulse oximetry to detect hypoxemia. Roc-derived SpO2 threshold of ≤ 94% can predict hypoxemia (PaO2 < 60 mmHg) with a sensitivity of 100% and a specificity of 95%. Furthermore, there are associations between the ROC-derived SpO2 threshold of ≤ 97% and detection of hypoxemia (PaO2 < 70 mmHg) with a sensitivity of 100% and a specificity of 46%. The accuracy of pulse oximetry was not affected by the severity of liver disease in detection of hypoxemia. Provided that SpO2 is equal to or greater than 94%, attained from pulse oximetry can be used as a reliable and accurate substitute for the ABG measurements to evaluate hypoxemia in patients with end stage liver disease.

Repeated assessment of orthotopic glioma pO(2) by multi-site EPR oximetry: a technique with the potential to guide therapeutic optimization by repeated measurements of oxygen.

PubMed

Khan, Nadeem; Mupparaju, Sriram; Hou, Huagang; Williams, Benjamin B; Swartz, Harold

2012-02-15

Tumor hypoxia plays a vital role in therapeutic resistance. Consequently, measurements of tumor pO(2) could be used to optimize the outcome of oxygen-dependent therapies, such as, chemoradiation. However, the potential optimizations are restricted by the lack of methods to repeatedly and quantitatively assess tumor pO(2) during therapies, particularly in gliomas. We describe the procedures for repeated measurements of orthotopic glioma pO(2) by multi-site electron paramagnetic resonance (EPR) oximetry. This oximetry approach provides simultaneous measurements of pO(2) at more than one site in the glioma and contralateral cerebral tissue. The pO(2) of intracerebral 9L, C6, F98 and U251 tumors, as well as contralateral brain, were measured repeatedly for five consecutive days. The 9L glioma was well oxygenated with pO(2) of 27-36 mm Hg, while C6, F98 and U251 glioma were hypoxic with pO(2) of 7-12mm Hg. The potential of multi-site EPR oximetry to assess temporal changes in tissue pO(2) was investigated in rats breathing 100% O(2). A significant increase in F98 tumor and contralateral brain pO(2) was observed on day 1 and day 2, however, glioma oxygenation declined on subsequent days. In conclusion, EPR oximetry provides the capability to repeatedly assess temporal changes in orthotopic glioma pO(2). This information could be used to test and optimize the methods being developed to modulate tumor hypoxia. Furthermore, EPR oximetry could be potentially used to enhance the outcome of chemoradiation by scheduling treatments at times of increase in glioma pO(2). Copyright © 2011 Elsevier B.V. All rights reserved.

Pharmacological treatment of obstructive sleep apnea with a combination of pseudoephedrine and domperidone.

PubMed

Larrain, Augusto; Kapur, Vishesh K; Gooley, Ted A; Pope, Charles E

2010-04-15

To determine the effect of the drug combination domperidone and pseudoephedrine on nocturnal oximetry measurements and daytime sleepiness in patients with obstructive sleep apnea. We recruited patients with severe snoring and apneic episodes willing to undergo repeated nocturnal oximetry testing. Following baseline clinical history, Epworth Sleepiness Scale administration, and home overnight nocturnal oximetry, patients were started on weight-adjusted doses of domperidone and pseudoephedrine. Follow-up oximetry studies were performed at the patient's convenience. On the final visit, a repeat clinical history, Epworth score, and oximetry were obtained. Seventeen of 23 patients noted disappearance of snoring and apneic episodes. Another 2 patients reported improvement in snoring and no apneic episodes. All but one patient had a decrease in Epworth scores (mean decrease 9.4 (95% CI, 6.8-12.1, p < 0.0001). Mean oxygen saturation (2.5; 95% Cl, 0.66-4.41, p = 0.008), percent time with oxygen saturation < 90% (14.8; 95% CI, 24.4 to 5.2, p = 0.003), and the 4% oxygen desaturation index (18.2; 95% CI, 27.3 to 9.1, p < 0.0001) improved significantly. No adverse effects of treatment were noted. The combination of domperidone and pseudoephedrine improved self reported snoring and sleepiness, and may have improved apneic episodes and sleep-related nocturnal oxygen desaturation in patients with obstructive sleep apnea provided the proportion of time spent asleep did not diminish. This drug combination warrants further study as a treatment for obstructive sleep apnea. Obstructive sleep apnea; oximetry; sleepiness; domperidone; pseudoephedrine; pharmacotherapy; desaturation; treatment Larrain A; Kapur VK; Gooley TA; Pope CE. Pharmacological treatment of obstructive sleep apnea with a combination of pseudoephedrine and domperidone.

Accuracy of a continuous noninvasive hemoglobin monitor in intensive care unit patients.

PubMed

Frasca, Denis; Dahyot-Fizelier, Claire; Catherine, Karen; Levrat, Quentin; Debaene, Bertrand; Mimoz, Olivier

2011-10-01

To determine whether noninvasive hemoglobin measurement by Pulse CO-Oximetry could provide clinically acceptable absolute and trend accuracy in critically ill patients, compared to other invasive methods of hemoglobin assessment available at bedside and the gold standard, the laboratory analyzer. Prospective study. Surgical intensive care unit of a university teaching hospital. Sixty-two patients continuously monitored with Pulse CO-Oximetry (Masimo Radical-7). None. Four hundred seventy-one blood samples were analyzed by a point-of-care device (HemoCue 301), a satellite lab CO-Oximeter (Siemens RapidPoint 405), and a laboratory hematology analyzer (Sysmex XT-2000i), which was considered the reference device. Hemoglobin values reported from the invasive methods were compared to the values reported by the Pulse CO-Oximeter at the time of blood draw. When the case-to-case variation was assessed, the bias and limits of agreement were 0.0±1.0 g/dL for the Pulse CO-Oximeter, 0.3±1.3g/dL for the point-of-care device, and 0.9±0.6 g/dL for the satellite lab CO-Oximeter compared to the reference method. Pulse CO-Oximetry showed similar trend accuracy as satellite lab CO-Oximetry, whereas the point-of-care device did not appear to follow the trend of the laboratory analyzer as well as the other test devices. When compared to laboratory reference values, hemoglobin measurement with Pulse CO-Oximetry has absolute accuracy and trending accuracy similar to widely used, invasive methods of hemoglobin measurement at bedside. Hemoglobin measurement with pulse CO-Oximetry has the additional advantages of providing continuous measurements, noninvasively, which may facilitate hemoglobin monitoring in the intensive care unit.

Intravenous injection of indocyanine green results in an artificial transient desaturation by pulse oximetry.

PubMed

Ediriwickrema, Lilangi S; Francis, Jasmine H; Arslan-Carlon, Vittoria; Dalecki, Paul H; Brodie, Scott E; Marr, Brian P; Abramson, David H

2015-01-01

To describe a case series of transient oxygen desaturation measured by pulse oximetry during the intravenous infusion of indocyanine green to enhance transpupillary thermotherapy in treating retinoblastoma after ophthalmic artery chemosurgery. Retrospective descriptive case series. The intravenous administration of indocyanine green for ophthalmic angiography resulted in a transient drop in oxygen saturation as measured by Nellcor fingertip pulse oximetry in three children with retinoblastoma receiving indocyanine green-guided transpupillary thermotherapy. The magnitude of reduction ranged from 92% to 94% from an initial reading of 99% to 100% in each case, with an average duration of 3 minutes. Concurrent measurement of blood pressure, pulse, and expired CO2 showed no changes during this process. Administration of intravenous indocyanine green resulted in a transient desaturation by oximetry during transpupillary thermotherapy for children with retinoblastoma under anesthesia because of the fluorescent dye's absorption of red light in a manner similar to that of deoxygenated hemoglobin, thereby leading to transient instrument misinterpretation and miscalculation of arterial oxygenation.

An Electronic Patch for wearable health monitoring by reflectance pulse oximetry.

PubMed

Haahr, Rasmus G; Duun, Sune B; Toft, Mette H; Belhage, Bo; Larsen, Jan; Birkelund, Karen; Thomsen, Erik V

2012-02-01

We report the development of an Electronic Patch for wearable health monitoring. The Electronic Patch is a new health monitoring system incorporating biomedical sensors, microelectronics, radio frequency (RF) communication, and a battery embedded in a 3-dimensional hydrocolloid polymer. In this paper the Electronic Patch is demonstrated with a new optical biomedical sensor for reflectance pulse oximetry so that the Electronic Patch in this case can measure the pulse and the oxygen saturation. The reflectance pulse oximetry solution is based on a recently developed annular backside silicon photodiode to enable low power consumption by the light emitting components. The Electronic Patch has a disposable part of soft adhesive hydrocolloid polymer and a reusable part of hard polylaurinlactam. The disposable part contains the battery. The reusable part contains the reflectance pulse oximetry sensor and microelectronics. The reusable part is 'clicked' into the disposable part when the patch is prepared for use. The patch has a size of 88 mm by 60 mm and a thickness of 5 mm.

Electron Paramagnetic Resonance Oximetry as a Quantitative Method to Measure Cellular Respiration: A Consideration of Oxygen Diffusion Interference

PubMed Central

Presley, Tennille; Kuppusamy, Periannan; Zweier, Jay L.; Ilangovan, Govindasamy

2006-01-01

Electron paramagnetic resonance (EPR) oximetry is being widely used to measure the oxygen consumption of cells, mitochondria, and submitochondrial particles. However, further improvement of this technique, in terms of data analysis, is required to use it as a quantitative tool. Here, we present a new approach for quantitative analysis of cellular respiration using EPR oximetry. The course of oxygen consumption by cells in suspension has been observed to have three distinct zones: pO2-independent respiration at higher pO2 ranges, pO2-dependent respiration at low pO2 ranges, and a static equilibrium with no change in pO2 at very low pO2 values. The approach here enables one to comprehensively analyze all of the three zones together—where the progression of O2 diffusion zones around each cell, their overlap within time, and their potential impact on the measured pO2 data are considered. The obtained results agree with previously established methods such as high-resolution respirometry measurements. Additionally, it is also demonstrated how the diffusion limitations can depend on cell density and consumption rate. In conclusion, the new approach establishes a more accurate and meaningful model to evaluate the EPR oximetry data on cellular respiration to quantify related parameters using EPR oximetry. PMID:17012319

Pulse Oximetry Overestimates Oxygen Saturation in COPD.

PubMed

Amalakanti, Sridhar; Pentakota, Mohan Rao

2016-04-01

Measurement of oxygen saturation with a handheld pulse oximeter is widely practiced as a surrogate to invasive arterial blood gas analysis. Oxygen saturation is an important parameter in cases of COPD, but there are insufficient data on the role of pulse oximetry in patients with COPD, moreso in diseases across its spectrum, such as chronic bronchitis and emphysema. We assessed the performance of pulse oximetry in acute respiratory failure of patients with COPD. This was a cross-sectional, observational study. We studied 50 subjects with COPD admitted to the Government General Hospital, a 1,000-bed tertiary referral center in Guntur, India, from June 2013 to July 2013. Simultaneous reading of S(pO2) by a handheld pulse oximeter and S(aO2) by an automated arterial blood gas analyzer were taken. Pulse oximetry was sufficiently sensitive (84.60%) to hypoxemia in respiratory failure to be used in clinical situations. The mean difference (bias) between SaO2 and S(pO2) was -3.98 (95% CI -4.68 to 3.28). There was less sensitivity (82% vs. 85%) and positive predictive value (69% vs. 85%) of the pulse oximeter to respiratory failure in subjects with chronic bronchitis versus emphysema. Pulse oximetry performed poorly in comparison with the invasive arterial blood gas analysis. The variability of the readings was greater in the subjects with chronic bronchitis than in those with emphysema. Copyright © 2016 by Daedalus Enterprises.

An analysis on the theory of pulse oximetry by Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Fan, Shangchun; Cai, Rui; Xing, Weiwei; Liu, Changting; Chen, Guangfei; Wang, Junfeng

2008-10-01

The pulse oximetry is a kind of electronic instrument that measures the oxygen saturation of arterial blood and pulse rate by non-invasive techniques. It enables prompt recognition of hypoxemia. In a conventional transmittance type pulse oximeter, the absorption of light by oxygenated and reduced hemoglobin is measured at two wavelength 660nm and 940nm. But the accuracy and measuring range of the pulse oximeter can not meet the requirement of clinical application. There are limitations in the theory of pulse oximetry, which is proved by Monte Carlo method. The mean paths are calculated in the Monte Carlo simulation. The results prove that the mean paths are not the same between the different wavelengths.

Desaturation Patterns Detected by Oximetry in a Large Population of Athletes

ERIC Educational Resources Information Center

Garrido-Chamorro, Raul P.; Gonzalez-Lorenzo, Marta; Sirvent-Belando, Jose; Blasco-Lafarga, Cristina; Roche, Enrique

2009-01-01

Optimal exercise performance in well trained athletes can be affected by arterial oxygen saturation failure. Noninvasive detection of this phenomenon when performing a routine ergometric test can be a valuable tool for subsequent planning of the athlete's training, recovery, and nutrition. Oximetry has been used to this end. The authors studied…

The Effect of Skin Pigmentation on the Accuracy of Pulse Oximetry in Infants with Hypoxemia.

PubMed

Foglia, Elizabeth E; Whyte, Robin K; Chaudhary, Aasma; Mott, Antonio; Chen, Jodi; Propert, Kathleen J; Schmidt, Barbara

2017-03-01

To compare pulse oximetry measurement bias between infants with hypoxemia with either dark skin or light skin with Masimo Radical 7 and Nellcor Oximax. There was no significant difference in systematic bias based on skin pigment for either oximeter. Copyright © 2016 Elsevier Inc. All rights reserved.

Advances in Probes and Methods for Clinical EPR Oximetry

PubMed Central

Hou, Huagang; Khan, Nadeem; Jarvis, Lesley A.; Chen, Eunice Y.; Williams, Benjamin B.; Kuppusamy, Periannan

2015-01-01

EPR oximetry, which enables reliable, accurate, and repeated measurements of the partial pressure of oxygen in tissues, provides a unique opportunity to investigate the role of oxygen in the pathogenesis and treatment of several diseases including cancer, stroke, and heart failure. Building on significant advances in the in vivo application of EPR oximetry for small animal models of disease, we are developing suitable probes and instrumentation required for use in human subjects. Our laboratory has established the feasibility of clinical EPR oximetry in cancer patients using India ink, the only material presently approved for clinical use. We now are developing the next generation of probes, which are both superior in terms of oxygen sensitivity and biocompatibility including an excellent safety profile for use in humans. Further advances include the development of implantable oxygen sensors linked to an external coupling loop for measurements of deep-tissue oxygenations at any depth, overcoming the current limitation of 10 mm. This paper presents an overview of recent developments in our ability to make meaningful measurements of oxygen partial pressures in human subjects under clinical settings. PMID:24729217

Non-Invasive Measurements of Carboxyhemoglobin and Methemoglobin in Children with Sickle Cell Disease

PubMed Central

Caboot, Jason B.; Jawad, Abbas F.; McDonough, Joseph M.; Bowdre, Cheryl Y.; Arens, Raanan; Marcus, Carole L.; Mason, Thornton B.A.; Smith-Whitley, Kim; Ohene-Frempong, Kwaku; Allen, Julian L.

2012-01-01

SUMMARY Assessment of oxyhemoglobin saturation in patients with sickle cell disease (SCD) is vital for prompt recognition of hypoxemia. The accuracy of pulse oximeter measurements of blood oxygenation in SCD patients is variable, partially due to carboxyhemoglobin (COHb) and methemoglobin (MetHb), which decrease the oxygen content of blood. This study evaluated the accuracy and reliability of a non-invasive pulse co-oximeter in measuring COHb and MetHb percentages (SpCO and SpMet) in children with SCD. We hypothesized that measurements of COHb and MetHb by non-invasive pulse co-oximetry agree within acceptable clinical accuracy with those made by invasive whole blood co-oximetry. Fifty children with SCD-SS underwent pulse co-oximetry and blood co-oximetry while breathing room air. Non-invasive COHb and MetHb readings were compared to the corresponding blood measurements. The pulse co-oximeter bias was 0.1% for COHb and −0.22% for MetHb. The precision of the measured SpCO was ±2.1% within a COHb range of 0.4–6.1%, and the precision of the measured SpMet was ±0.33% within a MetHb range of 0.1–1.1%. Non-invasive pulse co-oximetry was useful in measuring COHb and MetHb levels in children with SCD. Although the non-invasive technique slightly overestimated the invasive COHb measurements and slightly underestimated the invasive MetHb measurements, there was close agreement between the two methods. PMID:22328189

Non-invasive measurements of carboxyhemoglobin and methemoglobin in children with sickle cell disease.

PubMed

Caboot, Jason B; Jawad, Abbas F; McDonough, Joseph M; Bowdre, Cheryl Y; Arens, Raanan; Marcus, Carole L; Mason, Thornton B A; Smith-Whitley, Kim; Ohene-Frempong, Kwaku; Allen, Julian L

2012-08-01

Assessment of oxyhemoglobin saturation in patients with sickle cell disease (SCD) is vital for prompt recognition of hypoxemia. The accuracy of pulse oximeter measurements of blood oxygenation in SCD patients is variable, partially due to carboxyhemoglobin (COHb) and methemoglobin (MetHb), which decrease the oxygen content of blood. This study evaluated the accuracy and reliability of a non-invasive pulse co-oximeter in measuring COHb and MetHb percentages (SpCO and SpMet) in children with SCD. We hypothesized that measurements of COHb and MetHb by non-invasive pulse co-oximetry agree within acceptable clinical accuracy with those made by invasive whole blood co-oximetry. Fifty children with SCD-SS underwent pulse co-oximetry and blood co-oximetry while breathing room air. Non-invasive COHb and MetHb readings were compared to the corresponding blood measurements. The pulse co-oximeter bias was 0.1% for COHb and -0.22% for MetHb. The precision of the measured SpCO was ± 2.1% within a COHb range of 0.4-6.1%, and the precision of the measured SpMet was ± 0.33% within a MetHb range of 0.1-1.1%. Non-invasive pulse co-oximetry was useful in measuring COHb and MetHb levels in children with SCD. Although the non-invasive technique slightly overestimated the invasive COHb measurements and slightly underestimated the invasive MetHb measurements, there was close agreement between the two methods. Copyright © 2012 Wiley Periodicals, Inc.

Development and clinical evaluation of a new sensor design for buccal pulse oximetry in horses.

PubMed

Reiners, J K; Rossdeutscher, W; Hopster, K; Kästner, S B R

2018-03-01

The use of pulse oximetry in horses is limited due to inadequate readings with conventional transmission sensor probes. The objectives of this study were to 1) develop an improved sensor design for horses to be used at an appropriate anatomical site, and 2) evaluate this design in an experimental study. In vivo experiment. A new sensor design for reflectance pulse oximetry at the buccal mucosa was developed. A conventional Nonin 2000SL sensor for transmission pulse oximetry was included into this design. Three different prototypes (N1, N2a, N2b) were constructed and used with the Nonin 2500A Vet pulse oximetry monitor. Thirteen anaesthetised warmblood horses were included into a desaturation protocol (100-70% SaO 2 ). SpO 2 and pulse frequency values were recorded, using SaO 2 calculated from blood gas analysis and invasive pulse frequency measurements as reference methods. Bias and precision were evaluated by calculations of the root mean square deviation (A rms ). The agreement of the methods was tested with Bland-Altman analysis. The quality of the pulse frequency readings determined the quality of the SpO 2 -readings. Good pulse signal strength resulted in a SpO 2 -accuracy comparable to that of the original sensor (Nonin 2000SL: A rms = 3%; N1: A rms = 3.60%; N2b: A rms = 3.46%). Especially at heart rates ≤30 bpm, pulse rate readings that were about twice as high as the reference value occurred. Their exclusion from the dataset resulted in a pulse rate accuracy similar to that of the original sensor. Bland-Altman plots showed limits of agreement typical of pulse oximeters. The pulse frequency accuracy requires further improvement. The usability in clinical cases needs to be tested. The new sensor design has been shown to be suitable for buccal pulse oximetry in horses. © 2017 EVJ Ltd.

Study protocol for the PHANTOM study: prehospital assessment of noninvasive tissue oximetry monitoring.

PubMed

Weatherall, Andrew; Garner, Alan; Lovell, Nigel; Redmond, Stephen; Lee, Anna; Skowno, Justin; Egan, Jonathan

2014-10-03

Traumatic brain injury is a major cause of mortality and morbidity worldwide. It can be worsened by secondary injury particularly with hypoxia or hypotension. Current prehospital guidelines emphasise regular measurement of peripheral oxygen saturation and blood pressure but there is no monitor in use to provide direct information relating to blood flow or oxygen delivery to the brain tissue. This prospective cohort study will assess the utility of near-infrared spectroscopy monitoring in prehospital medicine in demonstrating injury, pathophysiology and associations with long-term functional outcomes. A prospective cohort study will be conducted in prehospital services where physician/paramedic teams respond rapidly to patients suffering significant traumatic injuries. A study observer accompanying the clinical team will apply non-invasive near-infrared spectroscopy tissue oximetry using a Nonin EQUANOX 7610 Regional Oximetry monitor (TM Nonin Medical, Inc.). This will be applied to patients with traumatic injuries less than 30 minutes old requiring transport. Measurements will be taken at two sites on the forehead and one on the forearm. Clinical teams will be blinded to all monitoring values. Near-infrared spectroscopy tissue oximetry parameters of oxyhaemoglobin%, deoxyhaemoglobin%, total tissue haemoglobin index and regional oxygen saturation will be recorded. Separate statistical analysis relating to time spent with cerebral regional oxygen saturation values < 45% and time series analysis will be performed to demonstrate associations with acute phase outcomes including injuries seen on cerebral imaging, and long-term functional outcomes measured by Glasgow Outcome Score and Extended Glasgow Outcome Score will then be undertaken. This prospective cohort study will demonstrate associations evident from the earliest stages of prehospital treatment between near-infrared spectroscopy tissue oximetry values and both acute and long-term outcomes of patients suffering traumatic injuries. This may provide the basis for future interventional studies utilising near-infrared spectroscopy tissue oximetry to guide prehospital trauma care. This trial is registered with the Australian and New Zealand Clinical Trials Registry. The registration number is ACTRN12611001124921 .

Survey of the clinical assessment and utility of near-infrared cerebral oximetry in cardiac surgery.

PubMed

Zacharias, David G; Lilly, Kevin; Shaw, Cynthia L; Pirundini, Paul; Rizzo, Robert J; Body, Simon C; Longford, Nicholas T

2014-04-01

Near-infrared cerebral oximetry increasingly is used for monitoring during cardiac surgery. Nonetheless, the scientific basis for incorporating this technology into clinical practice, the indications for when to do so, and standard diagnostic and treatment algorithms for defining abnormal values are yet to be rigorously defined. The authors hypothesized that there would be (1) variation in clinical use and practices for near-infrared spectroscopy (NIRS), and (2) variation in management of patients when clinicians are provided with NIRS information. In order to test this hypothesis, they sought to assess the nature and strength of response heterogeneity among anesthesiologists and cardiac perfusionists when provided with cardiac surgery patient scenarios and cerebral oximetry data. A prospectively collected survey. A hospital-based, multi-institutional, multinational study. By e-mail, the authors surveyed the membership of the Society of Cardiovascular Anesthesiologists and the online Cardiovascular Perfusion Forum. This survey was focused on ascertaining what actions clinicians would take in each scenario, given case information and cerebral oximetry tracings. Questions were based on 11 patient scenarios selected to represent small, large, symmetric, or asymmetric decreases in measured regional cerebral oxygen saturation (rScO2) encountered during cardiac surgery. Information on the respondents' (n = 796; 73% anesthesiologists) clinical practice, demography, and cerebral oximetry utilization was collected. An index of dispersion was used to assess response heterogeneity overall and within demographic subgroups. The majority of respondents indicated that cerebral oximetry monitoring was either useful or an essential monitor, especially perfusionists and clinicians who used cerebral oximetry most frequently. There were marked differences in responses between perfusionists and anesthesiologists for 4 of the 6 scenarios (p<0.005 for each of these 4 scenarios) occurring during cardiopulmonary bypass. Scenarios having greatest rScO2 reduction or asymmetry in rScO2 were associated with the highest dispersion, indicating least agreement in management. Scenarios with mild or moderate rScO2 reduction were associated with the lowest dispersion, indicating greater agreement in management. Although experimental data gradually are accumulating to support the role for cerebral oximetry monitoring during cardiac surgery, the results of the present survey support the view that its role remains poorly defined, and consensus for its appropriate use is lacking. Importantly, the authors observed marked variation in the use, perceived utility, and management of patients for 4 of the 6 CPB scenarios between perfusionists and anesthesiologists who share the management of CPB. These findings support the need for well-designed, adequately-powered clinical trials examining the value of this technology. Copyright © 2014 Elsevier Inc. All rights reserved.

Pulse Oximetry in the Physics Lab: A Colorful Alternative to Traditional Optics Curricula

ERIC Educational Resources Information Center

Kutschera, Ellynne; Dunlap, Justin C.; Byrd, Misti; Norlin, Casey; Widenhorn, Ralf

2013-01-01

We designed a physics laboratory exercise around pulse oximetry, a noninvasive medical technique used to assess a patient's blood oxygen saturation. An alternative to a traditional optics and light lab, this exercise teaches the principles of light absorption, spectroscopy, and the properties of light, while simultaneously studying a common…

Cerebral oximetry in cardiac and major vascular surgery.

PubMed

Fischer, G W; Silvay, G

2010-01-01

We describe the development and current applications of cerebral oximetry (based on near-infrared reflectance spectroscopy) that can be used during cardiac and major vascular surgery to determined brain tissue oxygen saturation. There are presently three cerebral oximetry devices with FDA approval in the United States to measure and monitor cerebral tissue oxygen saturation. 1. INVOS (Somanetics Corporation, Troy, MI - recently COVIDIEN, Boulder, CO); FORE-SIGHT (CAS Medical Systems, Inc. Branford, CT); EQUANOX (Nonin Medical Inc.Minnesota, MN). All devices are portable, non-invasive and easy to use in operating room and intensive care unit. The data provided in these communication may provided information for improvement of perioperative neuromonitoring techniques, and may be crucial in the design of future clinical trials.

Evaluating the Use of Tissue Oximetry to Decrease Intensive Unit Monitoring for Free Flap Breast Reconstruction.

PubMed

Ricci, Joseph A; Vargas, Christina R; Ho, Olivia A; Lin, Samuel J; Tobias, Adam M; Lee, Bernard T

2017-07-01

Postoperative free flap care has historically required intensive monitoring for 24 hours in an intensive care unit. Continuous monitoring with tissue oximetry has allowed earlier detection of vascular compromise, decreasing flap loss and improving salvage. This study aims to identify whether a fast-track postoperative paradigm can be safely used with tissue oximetry to decrease intensive monitoring and costs. All consecutive microsurgical breast reconstructions performed at a single institution were reviewed (2008-2014) and cases requiring return to the operating room were identified. Data evaluated included patient demographics, the take back time course, and complications of flap loss and salvage. A cost-benefit analysis was performed to analyse the utility of a postoperative intensive monitoring setting. There were 900 flaps performed and 32 required an unplanned return to the operating room. There were 16 flaps that required a reexploration within the first 24 hours; the standard length of intensive unit monitoring. After 4 hours, there were 7 flaps (44%) detected by tissue oximetry for reexploration. After 15 hours of intensive monitoring postoperatively, cost analysis revealed that the majority (15/16; 94%) of failing flaps had been identified and the cost of identifying each subsequent failing flap exceeded the cost of another hour of intensive monitoring. The postoperative paradigm for microsurgical flaps has historically required intensive unit monitoring. Using tissue oximetry, a fast-track pathway can reduce time spent in an intensive monitoring setting from 24 to 15 hours with significant cost savings and minimal risk of missing a failing free flap.

Impact of medical training and clinical experience on the assessment of oxygenation and hypoxaemia after general anaesthesia: an observational study.

PubMed

Aust, Hansjörg; Kranke, Peter; Eberhart, Leopold H J; Afshari, Arash; Weber, Frank; Brieskorn, Melanie; Heine, Julian; Arndt, Christian; Rüsch, Dirk

2015-06-01

In Germany it is common practice to use pulse oximetry and supplementary oxygen only on request in patients breathing spontaneously transferred to the post-anaesthesia care unit (PACU) following surgery under general anaesthesia. The main aim was to study the influence of medical training and clinical experience on assessing SpO(2) and detecting hypoxaemia in these patients. The second aim was to do a preliminary assessment whether this practice can be found in countries other than Germany. Anaesthetists, nurses and medical students estimated SpO(2) in patients breathing room air at the end of transfer to the PACU following surgery (including all major surgical fields) under general anaesthesia. Estimated SpO(2) was compared to SpO(2) measured by pulse oximetry. A survey was carried out among European anaesthesists concerning the use of pulse oximetry and supplementary oxygen during patient transfer to the PACU. Hypoxaemia (SpO(2) < 90 %) occurred in 154 (13.5 %) out of 1,138 patients. Anaesthetists, nurses, and medical students identified only 25, 23, and 21 patients of those as being hypoxaemic, respectively. Clinical experience did not improve detection of hypoxaemia both in anaesthetists (p = 0.63) and nurses (p = 0.18). Use of pulse oximetry and supplemental oxygen during patient transfer to the PACU in European countries differs to a large extent. It seems to be applied only on request in many hospitals. Considering the uncertainty about deleterious effects of transient, short lasting hypoxaemia routine use of pulse oximetry is advocated for patient transfer to the PACU.

Trans-abdominal monitoring of fetal arterial blood oxygenation using pulse oximetry

NASA Astrophysics Data System (ADS)

Zourabian, Anna; Siegel, Andrew M.; Chance, Britton; Ramanujam, Nirmala; Rode, Martha; Boas, David A.

2000-10-01

Pulse oximetry (oxygen saturation monitoring) has markedly improved medical care in many fields, including anesthesiology, intensive care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the standard for intrapartum assessment of fetal well being. Fetal oxygen saturation monitoring is a new technique currently under development. It is potentially superior to electronic fetal heart rate monitoring (cardiotocography) because it allows direct assessment of both the fetal oxygen status and fetal tissue perfusion. Here we present the analysis for determining the most optimal wavelength selection for pulse oximetry. The wavelengths we chose as the most optimal are the first in the range of 670 - 720 nm and the second in the range of 825 - 925 nm. Further, we discuss the possible systematic errors during our measurements and their contribution to the obtained saturation results. We present feasibility studies for fetal pulse oximetry, monitored noninvasively through the maternal abdomen. Our preliminary experiments show that the fetal pulse can be discriminated from the maternal pulse and thus, in principle, the fetal arterial oxygen saturation can be obtained. We present the methodology for obtaining these data, and discuss the dependence of our measurements on the fetal position with respect to the optode assembly.

Design and implementation of a sigma delta technology based pulse oximeter's acquisition stage

NASA Astrophysics Data System (ADS)

Rossi, E. E.; Peñalva, A.; Schaumburg, F.

2011-12-01

Pulse oximetry is a widely used tool in medical practice for estimating patient's fraction of hemoglobin bonded to oxygen. Conventional oximetry presents limitations when changes in the baseline, or low amplitude of signals involved occur. The aim of this paper is to simultaneously solve these constraints and to simplify the circuitry needed, by using ΣΔ technology. For this purpose, a board for the acquisition of the needed signals was developed, together with a PC managed software which controls it, and displays and processes in real time the information acquired. Also laboratory and field tests where designed and executed to verify the performance of this equipment in adverse situations. A simple, robust and economic instrument was achieved, capable of obtaining signals even in situations where conventional oximetry fails.

PubMed Central

PIUMETTO, E.; SAMMARTANO, A.M.; MEINARDI, G.; DAGNA, F.; GERVASIO, F.C.; ALBERA, R.

2011-01-01

SUMMARY Obstructive sleep apnoea syndrome in a child is characterized by prolonged episodes of obstructive hypopnoea and/or apnoea of upper airway leading to morbidity. The most common risk factor is adeno-tonsillar hypertrophy. Obstructive sleep apnoea syndrome diagnosis is based on clinical ENT evaluation and an instrumental approach, such as pulse oximetry or the gold standard overnight polysomnography. The aim is to establish, in a population of children with suspected obstructive sleep apnoea syndrome, the frequency of this disorder, the effect of adenotonsillectomy and the risk of post-operative complications. A total of 481 patients (297 male, 184 female) with suspected obstructive sleep apnoea syndrome (aged 2-14 years) were evaluated between March 2007 and April 2010 and divided into 3 morphological phenotypes: classic, adult and congenital. All patients underwent ENT assessment and a pulse oximetry with 4 channels cardiopulmonary monitoring. The examination following the Brouillette criteria was defined as negative, positive or inconclusive; when positive, adenotonsillectomy was the first therapeutic approach. At 6 months after surgery, all patients underwent check-up pulse oximetry. Of the overall sample, 96% of the patients had a classical phenotype, 3% an adult type and 1% a congenital type. The monitoring resulted pathological in 19% (17% of them were at increased post-operative risk), negative in 61% and inconclusive in 20%. All 5 patients with congenital phenotype were positive. Of the positive patients, 86% underwent adenotonsillectomy and a control pulse oximetry 6 months thereafter, 96% resulted negative. Pulse oximetry was efficient in order to avoid incorrect surgery indications, improving appropriateness and safety of adenotonsillectomy in children with obstructive sleep apnoea syndrome. Adenotonsillectomy showed a success rate of 96% and there were no episodes of post-surgery complications in particular in those patients at increased risk. PMID:22058592

Assessment of continuous acoustic respiratory rate monitoring as an addition to a pulse oximetry-based patient surveillance system.

PubMed

McGrath, Susan P; Pyke, Joshua; Taenzer, Andreas H

2017-06-01

Technology advances make it possible to consider continuous acoustic respiratory rate monitoring as an integral component of physiologic surveillance systems. This study explores technical and logistical aspects of augmenting pulse oximetry-based patient surveillance systems with continuous respiratory rate monitoring and offers some insight into the impact on patient deterioration detection that may result. Acoustic respiratory rate sensors were introduced to a general care pulse oximetry-based surveillance system with respiratory rate alarms deactivated. Simulation was used after 4324 patient days to determine appropriate alarm thresholds for respiratory rate, which were then activated. Data were collected for an additional 4382 patient days. Physiologic parameters, alarm data, sensor utilization and patient/staff feedback were collected throughout the study and analyzed. No notable technical or workflow issues were observed. Sensor utilization was 57 %, with patient refusal leading reasons for nonuse (22.7 %). With respiratory rate alarm thresholds set to 6 and 40 breaths/min., the majority of nurse pager clinical notifications were triggered by low oxygen saturation values (43 %), followed by low respiratory rate values (21 %) and low pulse rate values (13 %). Mean respiratory rate collected was 16.6 ± 3.8 breaths/min. The vast majority (82 %) of low oxygen saturation states coincided with normal respiration rates of 12-20 breaths/min. Continuous respiratory rate monitoring can be successfully added to a pulse oximetry-based surveillance system without significant technical, logistical or workflow issues and is moderately well-tolerated by patients. Respiratory rate sensor alarms did not significantly impact overall system alarm burden. Respiratory rate and oxygen saturation distributions suggest adding continuous respiratory rate monitoring to a pulse oximetry-based surveillance system may not significantly improve patient deterioration detection.

Assessment of oximetry-based statistical classifiers as simplified screening tools in the management of childhood obstructive sleep apnea.

PubMed

Crespo, Andrea; Álvarez, Daniel; Kheirandish-Gozal, Leila; Gutiérrez-Tobal, Gonzalo C; Cerezo-Hernández, Ana; Gozal, David; Hornero, Roberto; Del Campo, Félix

2018-02-16

A variety of statistical models based on overnight oximetry has been proposed to simplify the detection of children with suspected obstructive sleep apnea syndrome (OSAS). Despite the usefulness reported, additional thorough comparative analyses are required. This study was aimed at assessing common binary classification models from oximetry for the detection of childhood OSAS. Overnight oximetry recordings from 176 children referred for clinical suspicion of OSAS were acquired during in-lab polysomnography. Several training and test datasets were randomly composed by means of bootstrapping for model optimization and independent validation. For every child, blood oxygen saturation (SpO 2 ) was parameterized by means of 17 features. Fast correlation-based filter (FCBF) was applied to search for the optimum features. The discriminatory power of three statistical pattern recognition algorithms was assessed: linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), and logistic regression (LR). The performance of each automated model was evaluated for the three common diagnostic polysomnographic cutoffs in pediatric OSAS: 1, 3, and 5 events/h. Best screening performances emerged using the 1 event/h cutoff for mild-to-severe childhood OSAS. LR achieved 84.3% accuracy (95% CI 76.8-91.5%) and 0.89 AUC (95% CI 0.83-0.94), while QDA reached 96.5% PPV (95% CI 90.3-100%) and 0.91 AUC (95% CI 0.85-0.96%). Moreover, LR and QDA reached diagnostic accuracies of 82.7% (95% CI 75.0-89.6%) and 82.1% (95% CI 73.8-89.5%) for a cutoff of 5 events/h, respectively. Automated analysis of overnight oximetry may be used to develop reliable as well as accurate screening tools for childhood OSAS.

Pulse oximetry in the pulmonary tissue for the non-invasive measurement of mixed venous oxygen saturation.

PubMed

Nitzan, Meir; Nitzan, Itamar

2013-08-01

The oxygen saturation of the systemic arterial blood is associated with the adequacy of respiration, and can be measured non-invasively by pulse oximetry in the systemic tissue. The oxygen saturation of the blood in the pulmonary artery, the mixed venous blood, reflects the balance between oxygen supply to the systemic tissues and their oxygen demand. The mixed venous oxygen saturation has also clinical significance because it is used in Fick equation for the quantitative measurement of cardiac output. At present the measurement of the mixed venous oxygen saturation is invasive and requires insertion of a Swan-Ganz catheter into the pulmonary artery. We suggest a noninvasive method for the measurement of the mixed venous oxygen saturation in infants, pulmonary pulse oximetry. The method is similar to the systemic pulse oximetry, which is based on the different light absorption curves of oxygenated and deoxygenated hemoglobin and on the analysis of photoplethysmographic curves in two wavelengths. The proposed pulmonary pulse oximeter includes light-sources of two wavelengths in the infrared, which illuminate the pulmonary tissue through the thoracic wall. Part of the light which is scattered back from the pulmonary tissue and passes through the thoracic wall is detected, and for each wavelength a pulmonary photoplethysmographic curve is obtained. The pulmonary photoplethysmographic curves reflect blood volume increase during systole in the pulmonary arteries in the lung tissue, which contain mixed venous blood. The ratio R of the amplitude-to-baseline ratio for the two wavelengths is related to the mixed venous oxygen saturation through equations derived for the systemic pulse oximetry. The method requires the use of extinction coefficients values for oxygenated and deoxygenated hemoglobin, which can be found in the literature. Copyright © 2013 Elsevier Ltd. All rights reserved.

Incidence of Newborn Stabilization and Resuscitation Measures and Guideline Compliance during the First Minutes of Life in Norway.

PubMed

Skåre, Christiane; Kramer-Johansen, Jo; Steen, Thorbjørn; Ødegaard, Silje; Niles, Dana E; Nakstad, Britt; Solevåg, Anne L; Nadkarni, Vinay M; Olasveengen, Theresa M

2015-01-01

Most newborns manage the transition from intra- to extrauterine life without interventions, yet neonatal morbidity caused by failure of transition remains an important health problem. To determine the incidence of neonatal stabilization and resuscitation measures and guideline compliance during the first minutes after birth. This is a prospective, observational study of all births in three Norwegian hospitals. All interventions performed, including suctioning, use of pulse oximetry, continuous positive airway pressure (CPAP), positive pressure ventilation (PPV), supplemental oxygen, intubation, and administration of drugs, were registered at every on-call team shift during the study period. A total of 1,507 live-born infants were included, of whom 264 (18%) were brought to the resuscitation crib. Oropharyngeal suctioning was performed in 77 (5%), deep blind suctioning was carried out in 10 (1%) and 84 (6%) were monitored using pulse oximetry. PPV was provided in 58 cases (4%) - 8 (21%) of <34 weeks and 50 (3%) of ≥34 weeks of gestation. Sustained inflation is not routinely used in these departments. CPAP (without PPV) was provided in 17 cases (1%) - 4 (0.3%) were intubated and ventilated through the endotracheal tube. Supplemental oxygen was given to 39 infants (3%) - 9 without pulse oximetry monitoring. The median (interquartile range) birth weight and gestational age of the newborns requiring PPV and/or CPAP were 3,220 g (2,643-3,858) and 39 weeks (37-41), respectively. In this study, the need for resuscitation and/or stabilization measures was commonly considered, and 4% of all newborns received PPV. Despite strong guideline emphasis on the use of pulse oximetry to guide oxygen administration, many infants received oxygen treatment without pulse oximetry monitoring. © 2015 S. Karger AG, Basel.

Global operating theatre distribution and pulse oximetry supply: an estimation from reported data.

PubMed

Funk, Luke M; Weiser, Thomas G; Berry, William R; Lipsitz, Stuart R; Merry, Alan F; Enright, Angela C; Wilson, Iain H; Dziekan, Gerald; Gawande, Atul A

2010-09-25

Surgery is an essential part of health care, but resources to ensure the availability of surgical services are often inadequate. We estimated the global distribution of operating theatres and quantified the availability of pulse oximetry, which is an essential monitoring device during surgery and a potential measure of operating theatre resources. We calculated ratios of the number of operating theatres to hospital beds in seven geographical regions worldwide on the basis of profiles from 769 hospitals in 92 countries that participated in WHO's safe surgery saves lives initiative. We used hospital bed figures from 190 WHO member states to estimate the number of operating theatres per 100,000 people in 21 subregions throughout the world. To estimate availability of pulse oximetry, we sent surveys to anaesthesia providers in 72 countries selected to ensure a geographically and demographically diverse sample. A predictive regression model was used to estimate the pulse oximetry need for countries that did not provide data. The estimated number of operating theatres ranged from 1·0 (95% CI 0·9-1·2) per 100,000 people in west sub-Saharan Africa to 25·1 (20·9-30·1) per 100,000 in eastern Europe. High-income subregions all averaged more than 14 per 100,000 people, whereas all low-income subregions, representing 2·2 billion people, had fewer than two theatres per 100,000. Pulse oximetry data from 54 countries suggested that around 77,700 (63,195-95,533) theatres worldwide (19·2% [15·2-23·9]) were not equipped with pulse oximeters. Improvements in public-health strategies and monitoring are needed to reduce disparities for more than 2 billion people without adequate access to surgical care. WHO. Copyright © 2010 Elsevier Ltd. All rights reserved.

Pharmacological Treatment of Obstructive Sleep Apnea with a Combination of Pseudoephedrine and Domperidone

PubMed Central

Larrain, Augusto; Kapur, Vishesh K.; Gooley, Ted A.; Pope, Charles E.

2010-01-01

Study Objectives: To determine the effect of the drug combination domperidone and pseudoephedrine on nocturnal oximetry measurements and daytime sleepiness in patients with obstructive sleep apnea. Methods: We recruited patients with severe snoring and apneic episodes willing to undergo repeated nocturnal oximetry testing. Following baseline clinical history, Epworth Sleepiness Scale administration, and home overnight nocturnal oximetry, patients were started on weight-adjusted doses of domperidone and pseudoephedrine. Follow-up oximetry studies were performed at the patient's convenience. On the final visit, a repeat clinical history, Epworth score, and oximetry were obtained. Results: Sixteen of 23 patients noted disappearance of snoring and apneic episodes. Another 3 patients reported improvement in snoring and no apneic episodes. All but one patient had a decrease in Epworth scores (mean decrease 9.9 (95% CI, 7.2-12.6, p < 0.0001). Mean oxygen saturation (2.5; 95% CI, 0.66-4.41, p = 0.008), percent time with oxygen saturation < 90% (14.8; 95% CI, 24.4 to 5.2, p = 0.003), and the 4% oxygen desaturation index (18.2; 95% CI, 27.3 to 9.1, p < 0.0001) improved significantly. No adverse effects of treatment were noted. Conclusions: The combination of domperidone and pseudoephedrine improved self reported snoring and sleepiness, and may have improved apneic episodes and sleep-related nocturnal oxygen desaturation in patients with obstructive sleep apnea provided the proportion of time spent asleep did not diminish. This drug combination warrants further study as a treatment for obstructive sleep apnea. Citation: Larrain A; Kapur VK; Gooley TA; Pope CE. Pharmacological treatment of obstructive sleep apnea with a combination of pseudoephedrine and domperidone. J Clin Sleep Med 2010;6(2):117-123. PMID:20411686

Theoretical considerations to optimize transabdominal monitoring of fetal arterial blood oxygenation using pulse oximetry

NASA Astrophysics Data System (ADS)

Zourabian, Anna; Boas, David A.

2001-06-01

Pulse oximetry (oxygen saturation monitoring) has markedly improved medical care in many fields, including anesthesiology, intensive care, and newborn intensive care. In obstetrics, fetal heart rate monitoring remains the standard for intrapartum assessment of fetal well being. Fetal oxygen saturation monitoring is a new technique currently under development. It is potentially superior to electronic fetal heart rate monitoring (cardiotocography) because it allows direct assessment of both fetal oxygen status and fetal tissue perfusion. Here we present the analysis for determining the most optimal wavelength selection for pulse oximetry. The wavelengths we chose as the most optimal are: the first in the range of 670-720nm and the second in the range of 825-925nm. Further we discuss the possible systematic errors during our measurements, and their contribution to the obtained saturation results.

Quantitative impact of small angle forward scatter on whole blood oximetry using a Beer-Lambert absorbance model.

PubMed

LeBlanc, Serge Emile; Atanya, Monica; Burns, Kevin; Munger, Rejean

2011-04-21

It is well known that red blood cell scattering has an impact on whole blood oximetry as well as in vivo retinal oxygen saturation measurements. The goal of this study was to quantify the impact of small angle forward scatter on whole blood oximetry for scattering angles found in retinal oximetry light paths. Transmittance spectra of whole blood were measured in two different experimental setups: one that included small angle scatter in the transmitted signal and one that measured the transmitted signal only, at absorbance path lengths of 25, 50, 100, 250 and 500 µm. Oxygen saturation was determined by multiple linear regression in the 520-600 nm wavelength range and compared between path lengths and experimental setups. Mean calculated oxygen saturation differences between setups were greater than 10% at every absorbance path length. The deviations to the Beer-Lambert absorbance model had different spectral dependences between experimental setups, with the highest deviations found in the 520-540 nm range when scatter was added to the transmitted signal. These results are consistent with other models of forward scatter that predict different spectral dependences of the red blood cell scattering cross-section and haemoglobin extinction coefficients in this wavelength range.

A hand-held EPR scanner for transcutaneous oximetry

NASA Astrophysics Data System (ADS)

Wolfson, Helen; Ahmad, Rizwan; Twig, Ygal; Blank, Aharon; Kuppusamy, Periannan

2015-03-01

Cutaneous (skin) oxygenation is an important prognostic factor for the treatment of chronic wounds, skin cancer, diabetes side effects, and limb amputation. Currently, there are no reliable methods for measuring this parameter. Oximetry, using electron paramagnetic resonance (EPR) spectroscopy, is emerging as a potential tool for clinical oximetry, including cutaneous applications. The problem with EPR oximetry, however, is that the conventional EPR design requires the use of a large magnet that can generate homogeneous field across the sample, making it unattractive for clinical practice. We present a novel approach that makes use of a miniature permanent magnet, combined with a small microwave resonator, to enable the acquisition of EPR signals from paramagnetic species placed on the skin. The instrumentation consists of a hand-held, modular, cylindrical probehead with overall dimensions of 36-mm diameter and 24-mm height, with 150-g weight. The probehead includes a Halbach array of 16 pieces (4×4×8 mm3) of Sm-Co permanent magnet and a loop-gap resonator (2.24 GHz). Preliminary measurements using a Hahn-echo pulse sequence (800 echos in 20 ms) showed a signalto- noise ratio of ~70 compared to ~435 in a homogenous magnet under identical settings. Further work is in progress to improve the performance of the probehead and to optimize the hand-held system for clinical use

A Novel Approach to Monitoring Prostate Tumor Oxygenation: Proton MRI of the Reporter Molecule Hexamethyldisiloxane

DTIC Science & Technology

2006-03-01

potentially by MRI. This opens new opportunities for MR tumor oximetry, particularly since HMDSO is used widely in biomedical materials and as an...growth rate and respiratory challenge, Month 12-24 4 Body: Hexamethyldisiloxane (HMDSO) is used widely in biomedical materials and as an...opportunities for MR tumor oximetry, particularly since HMDSO is used widely in biomedical materials and as an ingredient in consumer products; and

A multiwavelength frequency-domain near-infrared cerebral oximeter

NASA Astrophysics Data System (ADS)

Kurth, C. Dean; Thayer, William S.

1999-03-01

This study tests a multiwavelength frequency-domain near-infrared oximeter (fdNIRS) in an in vitro model of the human brain. The model is a solid plastic structure containing a vascular network perfused with blood in which haemoglobin oxygen saturation was measured by co-oximetry, providing a standard for comparison. Plastic shells of varying thickness (0.5-2 cm), with a vascular network of their own and encircling the brain model, were also added to simulate extracranial tissues of the infant, child and adult. The fdNIRS oximeter utilizes frequency-domain technology to monitor phaseshifts at 754 nm, 785 nm and 816 nm relative to a 780 nm reference to derive through photon transport and Beer-Lambert equations. We found a linear relationship between fdNIRS and co-oximetry with excellent correlation that fitted the line of identity in all experiments ( n = 7). The bias of fdNIRS oximetry was -2% and the precision was 6%. Blood temperature and fdNIRS source-detector distance did not affect fdNIRS oximetry. Low haemoglobin concentration altered the fdNIRS versus co-oximetry line slope and intercept, producing a 15% error at the extremes of . The infant- and child-like shells overlying the brain model did not alter fdNIRS oximetry, whereas the adult-like shell yielded an error as high as 32%. In conclusion, fdNIRS accurately measures in an in vitro brain model, although low haemoglobin concentration and extracranial tissue of adult thickness influence accuracy.

Children with a history of prematurity presenting with snoring and sleep-disordered breathing: a cross-sectional study.

PubMed

Manuel, Anura; Witmans, Manisha; El-Hakim, Hamdy

2013-08-01

To report on the prevalence of premature (PM) birth in a consecutive series of children treated for snoring and sleep-disordered breathing (S/SDB), the parameters specific to their management and variables predictive of disease severity. A retrospective study was undertaken at a tertiary pediatric hospital. Children with history of PM and presenting with S/SDB were identified from a prospectively kept surgical database. We set out to determine the prevalence of PM among the patients presenting with S/SDB who required airway evaluations and surgery. Pulse oximetry is overnight recordable oxygen saturation and heart rate tracing that provides information about hypoxemia during sleep. This was performed on all children preoperatively. The pulse oximetry findings were used to plan for perioperative monitoring and care. A multivariable analysis was used to identify factors predictive of abnormal pulse oximetry studies. We evaluated the associated diagnoses, surgical procedures required, and response to treatment in these selected children. Fifty-seven out of 1,038 patients were PM (33 males; mean age, 62.09 ± 34.91 months; range, 4-190 months). The mean gestational age was 30.3 ± 4.0 weeks. The prevalence rate of PM among patients treated surgically for SDB is 5.5% (95% CI 5.2-5.8) at our center. Comorbid pulmonary and gastrointestinal disorders were encountered on 23 (40%) and 17 (29.8%) occasions, respectively, and were the most commonly encountered comorbid diagnostic categories. Large airway abnormalities were encountered in 11 (19.3%) children, and the most common were subglottic stenosis (four) and laryngeal paralysis (four). Comorbid respiratory disease was negatively predictive of abnormal pulse oximetry (coefficient -0.35, P<.05). Postoperative respiratory outcomes correlated with abnormal pulse oximetry (coefficient 0.3; P<.05). Our findings suggest children with PM presenting to pediatric otolaryngology require a comprehensive evaluation for S/SDB. A significant proportion of children with S/SDB and a history of PM frequently had pulmonary and gastrointestinal comorbidities in our cohort. One-half required admission postoperatively, and these were predictable based on preoperative pulse oximetry. Respiratory comorbidity was negatively predictive of severity of SDB. Inversely, children with untreated pulmonary comorbidities are more likely to have postoperative complications. © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

Type III home sleep testing versus pulse oximetry: is the respiratory disturbance index better than the oxygen desaturation index to predict the apnoea-hypopnoea index measured during laboratory polysomnography?

PubMed

Dawson, Arthur; Loving, Richard T; Gordon, Robert M; Abel, Susan L; Loewy, Derek; Kripke, Daniel F; Kline, Lawrence E

2015-06-30

In its guidelines on the use of portable monitors to diagnose obstructive sleep apnoea, the American Academy of Sleep Medicine endorses home polygraphy with type III devices recording at a minimum airflow the respiratory effort and pulse oximetry, but advises against simple pulse oximetry. However, oximetry is widely available and simple to use in the home. This study was designed to compare the ability of the oxygen desaturation index (ODI) based on oximetry alone with a stand-alone pulse oximeter (SPO) and from the oximetry channel of the ApneaLink Plus (ALP), with the respiratory disturbance index (RDI) based on four channels from the ALP to predict the apnoea-hypopnoea index (AHI) from laboratory polysomnography. Cross-sectional diagnostic accuracy study. Sleep medicine practice of a multispecialty clinic. Patients referred for laboratory polysomnography with suspected sleep apnoea. We enrolled 135 participants with 123 attempting the home sleep testing and 73 having at least 4 hours of satisfactory data from SPO and ALP. Participants had home testing performed simultaneously with both a SPO and an ALP. The 2 oximeter probes were worn on different fingers of the same hand. The ODI for the SPO was calculated using Profox software (ODI(SOX)). For the ALP, RDI and ODI were calculated using both technician scoring (RDI(MAN) and ODI(MAN)) and the ALP computer scoring (RDI(RAW) and ODI(RAW)). The receiver-operator characteristic areas under the curve for AHI ≥ 5 were RDI(MAN) 0.88 (95% confidence limits 0.81-0.96), RDI(RAW) 0.86 (0.76-0.94), ODI(MAN) 0.86 (0.77-0.95), ODI(RAW) 0.84 (0.75-0.93) and ODI(SOX) 0.83 (0.73-0.93). We conclude that the RDI and the ODI, measured at home on the same night, give similar predictions of the laboratory AHI, measured on a different night. The differences between the two methods are small compared with the reported night-to-night variation of the AHI. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Finger blood content, light transmission, and pulse oximetry errors.

PubMed

Craft, T M; Lawson, R A; Young, J D

1992-01-01

The changes in light emitting diode current necessary to maintain a constant level of light incident upon a photodetector were measured in 20 volunteers at the two wavelengths employed by pulse oximeters. Three states of finger blood content were assessed; exsanguinated, hyperaemic, and normal. The changes in light emitting diode current with changes in finger blood content were small and are not thought to represent a significant source of error in saturation as measured by pulse oximetry.

Use of pulse co-oximetry as a screening and monitoring tool in mass carbon monoxide poisoning.

PubMed

Bledsoe, Bryan E; Nowicki, Kevin; Creel, James H; Carrison, Dale; Severance, Harry W

2010-01-01

Carbon monoxide (CO) poisoning remains a common cause of poisoning in the United States. We describe a case where responding fire department personnel encountered a sick employee with a headache at an automotive brake manufacturing plant. Using both atmospheric CO monitoring and pulse CO-oximetry technology, fire department personnel were able to diagnose the cause of the patient's illness and later identify the source of CO in the plant.

Sleep-Disordered Breathing in Patients with Pulmonary Valve Incompetence Complicating Congenital Heart Disease.

PubMed

Miles, Susan; Ahmad, Waheed; Bailey, Amy; Hatton, Rachael; Boyle, Andrew; Collins, Nicholas

2016-12-01

Long standing pulmonary regurgitation results in deleterious effects on right heart size and function with late consequences of right heart volume overload including ventricular dilatation, propensity to arrhythmia and right heart failure. As sleep disordered breathing may predispose to elevations in pulmonary vascular resistance and associated negative effects on right ventricular function, we sought to assess this in patients with underlying congenital heart disease. We performed a pilot study to evaluate the incidence of sleep-disordered breathing in a patient population with a history of long standing pulmonary valve incompetence in patients with congenital heart disease using overnight oximetry. Patients with a background of tetralogy of Fallot repair or residual pulmonary incompetence following previous pulmonary valve intervention for congenital pulmonary stenosis were included. Twenty-two patients underwent overnight oximetry. The mean age of the cohort was 34.3 ± 15.2 years with no patients observed to have severe underlying pulmonary hypertension. Abnormal overnight oximetry was seen in 13/22 patients (59.1%) with 2/22 (9.1%) patients considered to have severe abnormalities. An important proportion of patients with a background of pulmonary incompetence complicating congenital heart disease are prone to the development of sleep-disordered breathing as assessed by overnight oximetry. Further study into the prevalence and mechanisms of sleep-disordered breathing in a larger cohort are warranted. © 2016 Wiley Periodicals, Inc.

Heart Rate Assessment Immediately after Birth.

PubMed

Phillipos, Emily; Solevåg, Anne Lee; Pichler, Gerhard; Aziz, Khalid; van Os, Sylvia; O'Reilly, Megan; Cheung, Po-Yin; Schmölzer, Georg M

2016-01-01

Heart rate assessment immediately after birth in newborn infants is critical to the correct guidance of resuscitation efforts. There are disagreements as to the best method to measure heart rate. The aim of this study was to assess different methods of heart rate assessment in newborn infants at birth to determine the fastest and most accurate method. PubMed, EMBASE and Google Scholar were systematically searched using the following terms: 'infant', 'heart rate', 'monitoring', 'delivery room', 'resuscitation', 'stethoscope', 'auscultation', 'palpation', 'pulse oximetry', 'electrocardiogram', 'Doppler ultrasound', 'photoplethysmography' and 'wearable sensors'. Eighteen studies were identified that described various methods of heart rate assessment in newborn infants immediately after birth. Studies examining auscultation, palpation, pulse oximetry, electrocardiography and Doppler ultrasound as ways to measure heart rate were included. Heart rate measurements by pulse oximetry are superior to auscultation and palpation, but there is contradictory evidence about its accuracy depending on whether the sensor is connected to the infant or the oximeter first. Several studies indicate that electrocardiogram provides a reliable heart rate faster than pulse oximetry. Doppler ultrasound shows potential for clinical use, however future evidence is needed to support this conclusion. Heart rate assessment is important and there are many measurement methods. The accuracy of routinely applied methods varies, with palpation and auscultation being the least accurate and electrocardiogram being the most accurate. More research is needed on Doppler ultrasound before its clinical use. © 2015 S. Karger AG, Basel.

Prevention of retinopathy of prematurity in preterm infants through changes in clinical practice and SpO₂technology.

PubMed

Castillo, Armando; Deulofeut, Richard; Critz, Ann; Sola, Augusto

2011-02-01

To identify whether pulse oximetry technology is associated with decreased retinopathy of prematurity (ROP) and laser treatment. Inborn infants <1250 g who had eye exams were compared at two centres in three periods. In Period 1, SpO₂ target was ≥93% and pulse oximetry technology was the same in both Centres. In Period 2, guidelines for SpO₂ 88-93% were implemented at both centres and Centre B changed to oximeters with signal extraction technology (SET(®)) while Centre A did not, but did so in Period 3. One ophthalmology department performed eye exams using international criteria. In 571 newborns <1250 g, birth weight and gestational age were similar in the different periods and centres. At Centre A, severe ROP and need for laser remained the same in Periods 1 and 2, decreasing in Period 3-6% and 3%, respectively. At Centre B, severe ROP decreased from 12% (Period 1) to 5% (Period 2) and need for laser decreased from 5% to 3%, remaining low in Period 3. In a large group of inborn infants <1250 g, a change in clinical practice in combination with pulse oximetry with Masimo SET, but not without it, led to significant reduction in severe ROP and need for laser therapy. Pulse oximetry selection is important in managing critically ill infants. © 2010 The Author(s)/Acta Paediatrica © 2010 Foundation Acta Paediatrica.

First day of life pulse oximetry screening to detect congenital heart defects.

PubMed

Meberg, Alf; Brügmann-Pieper, Sabine; Due, Reidar; Eskedal, Leif; Fagerli, Ingebjørg; Farstad, Teresa; Frøisland, Dag Helge; Sannes, Catharina Hovland; Johansen, Ole Jakob; Keljalic, Jasmina; Markestad, Trond; Nygaard, Egil Andre; Røsvik, Alet; Silberg, Inger Elisabeth

2008-06-01

To evaluate the efficacy of first day of life pulse oximetry screening to detect congenital heart defects (CHDs). We performed a population-based prospective multicenter study of postductal (foot) arterial oxygen saturation (SpO(2)) in apparently healthy newborns after transfer from the delivery suite to the nursery. SpO(2) < 95% led to further diagnostic evaluations. Of 57,959 live births, 50,008 (86%) were screened. In the screened population, 35 CHDs were [corrected] classified as critical (ductus dependent, cyanotic). CHDs were prospectively registered and diagnosed in 658/57,959 (1.1%) [corrected] Of the infants screened, 324 (0.6%) failed the test. Of these, 43 (13%) had CHDs (27 critical), and 134 (41%) had pulmonary diseases or other disorders. The remaining 147 infants (45%) were healthy with transitional circulation. The median age for babies with CHDs at failing the test was 6 hours (range, 1-21 hours). For identifying critical CHDs, the pulse oximetry screening had a sensitivity rate of 77.1% (95% CI, 59.4-89.0), specificity rate of 99.4% (95% CI, 99.3-99.5), and a false-positive rate of 0.6% (95% CI, 0.5-0.7). Early pulse oximetry screening promotes early detection of critical CHDs and other potentially severe diseases. The sensitivity rate for detecting critical CHDs is high, and the false-positive rate is low.

Noninvasive quantification of left-to-right shunt by phase contrast magnetic resonance imaging in secundum atrial septal defect: the effects of breath holding and comparison with invasive oximetry.

PubMed

Yamasaki, Yuzo; Kawanami, Satoshi; Kamitani, Takeshi; Sagiyama, Koji; Sakamoto, Ichiro; Hiasa, Ken-Ichi; Yabuuchi, Hidetake; Nagao, Michinobu; Honda, Hiroshi

2018-01-16

To investigate the effect of breath-holding on left-to-right shunts in patients with a secundum atrial septal defect (ASD). Thirty-five consecutive patients with secundum ASDs underwent right heart catheterization and invasive oximetry. Phase-contrast magnetic resonance imaging (MRI) was performed for the main pulmonary artery and ascending aorta. All measurements were obtained during free breathing (FB) (quiet breathing; no breath-hold), expiratory breath-hold (EBH), and inspiratory breath-hold (IBH). Pulmonary circulation flow (Qp) and systemic circulation flow (Qs) were calculated by multiplying the heart rate by the stroke volume. Measurements during FB, EBH, and IBH were compared, and the differences compared to invasive oximetry were evaluated. There were significant differences among the measurements during FB, EBH, and IBH for Qp (FB, 7.70 ± 2.68; EBH, 7.18 ± 2.34; IBH, 6.88 ± 2.51 l/min); however, no significant difference was found for Qs (FB, 3.44 ± 0.74; EBH, 3.40 ± 0.83; IBH, 3.40 ± 0.86 l/min). There were significant differences among the measurements during FB, EBH, and IBH for Qp/Qs (FB, 2.38 ± 1.12; EBH, 2.24 ± 0.95; IBH, 2.14 ± 0.97). Qp/Qs during FB and EBH correlated better with Qp/Qs measured by invasive oximetry than did IBH. The limit of agreement was smaller for EBH than for FB and IBH. In patients with secundum ASDs, Qp/Qs significantly decreased with breath-holding. The accuracy of the Qp/Qs measurement by MRI compared with invasive oximetry during EBH was higher than during FB and IBH.

Identifying individual sleep apnea/hypoapnea epochs using smartphone-based pulse oximetry.

PubMed

Garde, Ainara; Dekhordi, Parastoo; Ansermino, J Mark; Dumont, Guy A

2016-08-01

Sleep apnea, characterized by frequent pauses in breathing during sleep, poses a serious threat to the healthy growth and development of children. Polysomnography (PSG), the gold standard for sleep apnea diagnosis, is resource intensive and confined to sleep laboratories, thus reducing its accessibility. Pulse oximetry alone, providing blood oxygen saturation (SpO2) and blood volume changes in tissue (PPG), has the potential to identify children with sleep apnea. Thus, we aim to develop a tool for at-home sleep apnea screening that provides a detailed and automated 30 sec epoch-by-epoch sleep apnea analysis. We propose to extract features characterizing pulse oximetry (SpO2 and pulse rate variability [PRV], a surrogate measure of heart rate variability) to create a multivariate logistic regression model that identifies epochs containing apnea/hypoapnea events. Overnight pulse oximetry was collected using a smartphone-based pulse oximeter, simultaneously with standard PSG from 160 children at the British Columbia Children's hospital. The sleep technician manually scored all apnea/hypoapnea events during the PSG study. Based on these scores we labeled each epoch as containing or not containing apnea/hypoapnea. We randomly divided the subjects into training data (40%), used to develop the model applying the LASSO method, and testing data (60%), used to validate the model. The developed model was assessed epoch-by-epoch for each subject. The test dataset had a median area under the receiver operating characteristic (ROC) curve of 81%; the model provided a median accuracy of 74% sensitivity of 75%, and specificity of 73% when using a risk threshold similar to the percentage of apnea/hypopnea epochs. Thus, providing a detailed epoch-by-epoch analysis with at-home pulse oximetry alone is feasible with accuracy, sensitivity and specificity values above 73% However, the performance might decrease when analyzing subjects with a low number of apnea/hypoapnea events.

Is pulse oximetry an essential tool or just another distraction? The role of the pulse oximeter in modern anesthesia care.

PubMed

Shah, Amit; Shelley, Kirk H

2013-06-01

Since the discovery of anesthetic agents, patient monitoring has been considered one of the core responsibilities of the anesthesiologist. As depicted in Robert Hinckley's famous painting, The First Operation with Ether, one observes William Thomas Green Morton carefully watching over his patient. Since its founding in 1905, 'Vigilance' has been the motto of the American Society of Anesthesiologists (ASA). Over a hundred years have passed, and one would think we would be clear regarding what we are watching for and how we should be watching. On the contrary, the introduction of new technology and outcome research is requiring us to re-examine our fundamental assumptions regarding what is and what is not important in the care of the patient. A vast majority of anesthesiologists would refuse to proceed with an anesthetic without the presence of a pulse oximeter. On the other hand, outcome studies have failed to demonstrate an improvement in patient care with their use. For that matter, it can be argued that outcome studies have yet to demonstrate an unambiguous role for any monitor of any type (i.e. blood pressure cuff or ECG), as outcome studies may fail to capture rare events. Because of the increased safety that has been attributed to pulse oximetry, it is unlikely that further studies can or will be conducted. As we enter a new era of clinical monitoring, with an emphasis on noninvasive cardiovascular monitoring, it might be of benefit to examine the role of the pulse oximeter in clinical care. This article reviews the available evidence for pulse oximetry. Further, it discusses contemporary issues, events, and perceptions that may help to explain how and why pulse oximetry may have been adopted as a standard of care despite the lack of supportive. Lastly, it discusses less obvious benefits of pulse oximetry that may have further implications on the future of anesthesia care and perhaps even automated anesthesia.

Optimal spacing between transmitting and receiving optical fibres in reflectance pulse oximetry

NASA Astrophysics Data System (ADS)

Hickey, M.; Kyriacou, P. A.

2007-10-01

Splanchnic ischaemia can ultimately lead to cellular hypoxia and necrosis, and may well contribute to the development of multiple organ failures and increased mortality. Therefore, it is of utmost importance to monitor abdominal organ blood oxygen saturation (SpO2). Pulse oximetry has been widely accepted as a reliable method for monitoring oxygen saturation of arterial blood. Animal studies have also shown it to be effective in the monitoring of blood oxygen saturation in the splanchnic region. However, commercially available pulse oximeter probes are not suitable for the continuous assessment of SpO2 in the splanchnic region. Therefore, there is a need for a new sensor technology that will allow the continuous measurement of SpO2 in the splanchnic area pre-operatively, operatively and post-operatively. For this purpose, a new fibre optic sensor and processing system utilising the principle of reflectance pulse oximetry has been developed. The accuracy in the estimation of SpO2 in pulse oximetry depends on the quality and amplitude of the photoplethysmographic (PPG) signal and for this reason an experimental procedure was carried out to examine the effect of the source-detector separation distance on the acquired PPG signals, and to ultimately select an optimal separation for the final design of the fibre-optic probe. PPG signals were obtained from the finger for different separation distances between the emitting and detecting fibres. Good quality PPG signals with large amplitudes and high signal-to-noise ratio were detected in the range of 3mm to 6mm. At separation distances between 1mm and 2mm, PPG signals were erratic with no resemblance to a conventional PPG signal. At separation distances greater than 6mm, the amplitudes of PPG signals were very small and not appropriate for processing. This investigation indicates the suitability of optical fibres as a new pulse oximetry sensor for estimating blood oxygen saturation (SpO2) in the splanchnic region.

Sleep problems in Dravet syndrome: a modifiable comorbidity.

PubMed

Licheni, Shane H; Mcmahon, Jacinta M; Schneider, Amy L; Davey, Margot J; Scheffer, Ingrid E

2018-02-01

Many children with severe developmental and epileptic encephalopathies experience significant sleep disturbance, causing major disruption to the family's quality of life. We aimed to determine the frequency and nature of sleep problems in individuals with Dravet syndrome. The Sleep Disturbance Scale for Children and a seizure questionnaire were distributed to the parents/guardians of 96 patients with Dravet syndrome. Sixteen patients had two nights of home oximetry. Fifty-seven out of 96 questionnaires were completed. Forty-three out of 57 (75%) individuals had sleep problems. Twenty-five out of 57 (44%) individuals had an abnormal total sleep score, with difficulty initiating and maintaining sleep (22 out of 57, 39%), sleep-wake transition disorders (20 out of 57, 35%), and sleep breathing disorders (19 out of 57, 33%). Twenty-two out of 57 (39%) individuals took medication to assist sleep, predominantly melatonin (n=14). Thirty out of 57 (53%) recently had nocturnal seizures. Overnight oximetry showed 14 out of 16 (88%) had a higher oxygen desaturation index (>3%), and six out of 16 (38%) had higher mean pulse rates than normative values. Home oximetry was normal or inconclusive in all patients. Seventy-five per cent of individuals with Dravet syndrome had sleep problems, highlighting the importance of routinely assessing sleep and initiating appropriate behavioural and pharmacological interventions to improve the patient and family's quality of life. A high oxygen desaturation index and mean pulse rates on pulse oximetry may reflect unrecognized nocturnal seizures. More than 70% of patients with Dravet syndrome have sleep problems. Difficulty initiating and maintaining sleep was most common, particularly in those older than 20 years. Second most common were sleep-wake transition disorders, affecting more than 50% of those younger than 5 years. Sleep breathing disorders were a frequent problem across all age groups. Oximetry was not diagnostic of sleep-disordered breathing or obvious seizures. © 2017 Mac Keith Press.

Automated graphic assessment of respiratory activity is superior to pulse oximetry and visual assessment for the detection of early respiratory depression during therapeutic upper endoscopy.

PubMed

Vargo, John J; Zuccaro, Gregory; Dumot, John A; Conwell, Darwin L; Morrow, J Brad; Shay, Steven S

2002-06-01

Recommendations from the American Society of Anesthesiologists suggest that monitoring for apnea using the detection of exhaled carbon dioxide (capnography) is a useful adjunct in the assessment of ventilatory status of patients undergoing sedation and analgesia. There are no data on the utility of capnography in GI endoscopy, nor is the frequency of abnormal ventilatory activity during endoscopy known. The aims of this study were to determine the following: (1) the frequency of abnormal ventilatory activity during therapeutic upper endoscopy, (2) the sensitivity of observation and pulse oximetry in the detection of apnea or disordered respiration, and (3) whether capnography provides an improvement over accepted monitoring techniques. Forty-nine patients undergoing therapeutic upper endoscopy were monitored with standard methods including pulse oximetry, automated blood pressure measurement, and visual assessment. In addition, graphic assessment of respiratory activity with sidestream capnography was performed in all patients. Endoscopy personnel were blinded to capnography data. Episodes of apnea or disordered respiration detected by capnography were documented and compared with the occurrence of hypoxemia, hypercapnea, hypotension, and the recognition of abnormal respiratory activity by endoscopy personnel. Comparison of simultaneous respiratory rate measurements obtained by capnography and by auscultation with a pretracheal stethoscope verified that capnography was an excellent indicator of respiratory rate when compared with the reference standard (auscultation) (r = 0.967, p < 0.001). Fifty-four episodes of apnea or disordered respiration occurred in 28 patients (mean duration 70.8 seconds). Only 50% of apnea or disordered respiration episodes were eventually detected by pulse oximetry. None were detected by visual assessment (p < 0.0010). Apnea/disordered respiration occurs commonly during therapeutic upper endoscopy and frequently precedes the development of hypoxemia. Potentially important abnormalities in respiratory activity are undetected with pulse oximetry and visual assessment.

Continuous, noninvasive, and localized microvascular tissue oximetry using visible light spectroscopy.

PubMed

Benaron, David A; Parachikov, Ilian H; Friedland, Shai; Soetikno, Roy; Brock-Utne, John; van der Starre, Peter J A; Nezhat, Camran; Terris, Martha K; Maxim, Peter G; Carson, Jeffrey J L; Razavi, Mahmood K; Gladstone, Hayes B; Fincher, Edgar F; Hsu, Christopher P; Clark, F Landon; Cheong, Wai-Fung; Duckworth, Joshua L; Stevenson, David K

2004-06-01

The authors evaluated the ability of visible light spectroscopy (VLS) oximetry to detect hypoxemia and ischemia in human and animal subjects. Unlike near-infrared spectroscopy or pulse oximetry (SpO2), VLS tissue oximetry uses shallow-penetrating visible light to measure microvascular hemoglobin oxygen saturation (StO2) in small, thin tissue volumes. In pigs, StO2 was measured in muscle and enteric mucosa during normoxia, hypoxemia (SpO2 = 40-96%), and ischemia (occlusion, arrest). In patients, StO2 was measured in skin, muscle, and oral/enteric mucosa during normoxia, hypoxemia (SpO2 = 60-99%), and ischemia (occlusion, compression, ventricular fibrillation). In pigs, normoxic StO2 was 71 +/- 4% (mean +/- SD), without differences between sites, and decreased during hypoxemia (muscle, 11 +/- 6%; P < 0.001) and ischemia (colon, 31 +/- 11%; P < 0.001). In patients, mean normoxic StO2 ranged from 68 to 77% at different sites (733 measures, 111 subjects); for each noninvasive site except skin, variance between subjects was low (e.g., colon, 69% +/- 4%, 40 subjects; buccal, 77% +/- 3%, 21 subjects). During hypoxemia, StO2 correlated with SpO2 (animals, r2 = 0.98; humans, r2 = 0.87). During ischemia, StO2 initially decreased at -1.3 +/- 0.2%/s and decreased to zero in 3-9 min (r2 = 0.94). Ischemia was distinguished from normoxia and hypoxemia by a widened pulse/VLS saturation difference (Delta < 30% during normoxia or hypoxemia vs. Delta > 35% during ischemia). VLS oximetry provides a continuous, noninvasive, and localized measurement of the StO2, sensitive to hypoxemia, regional, and global ischemia. The reproducible and narrow StO2 normal range for oral/enteric mucosa supports use of this site as an accessible and reliable reference point for the VLS monitoring of systemic flow.

Examination of a Novel Method for Non-Contact, Low-Cost, and Automated Heart-Rate Detection in Ambient Light Using Photoplethysmographic Imaging

DTIC Science & Technology

2014-10-01

a period of time by electrodes attached to the surface of the skin, are used in almost every clinical environment. Pulse oximeters , which measure the...medical devices, for example, pulse oximeters , vascular diagnostics, and digital beat-to-beat blood pressure measurement systems (Allen 2007). PPG is...principle is pulse oximetry. 1.2 Pulse Oximetry A pulse oximeter monitors the blood-oxygen saturation level and pulse rate in the human blood by using

A Comparison of Pulse-Oximetry, Near-Infrared Spectroscopy (NIRS), and Gas Sensors for In-Cockpit Hypoxia Detection

DTIC Science & Technology

2012-08-29

Pulse Oximetry: Arterial oxygen saturation (SpO2) at the index finger on the left hand was measured with a finger oximeter (Model 3900 P, Datex...minutes or until their finger O2 saturation levels dropped below 50%. Oxygen saturation was measured via the left index finger with a pulse oximeter ... saturation . Pulse oximeters have two light emitting diodes, using red (600-750 nm) and near infrared (850-1000 nm) light that penetrates the skin

FY12 Line-Supported Bio-Medical Initiative Program: Advanced Photoplethysmography (PPG) Sensors for Operational and Casualty Care Medicine

DTIC Science & Technology

2013-02-11

PPG) is measuring this size using light. A particular and ubiquitous application of PPG is in pulse oximetry, whereby the oxygenation saturation of...arterial blood is measured. Pulse oximetry requires absorption measurements of oxygenated (HbO2) and deoxygenated hemoglobin (Hb) at 940 nm (near-IR...relative quantity of Hb to HbO2 (i.e., SpO2) may be determined noninvasively. The advent of such a noninvasive arterial oxygen saturation measurement was a

Technical considerations in continuous jugular venous oxygen saturation measurement.

PubMed

Dearden, N M; Midgley, S

1993-01-01

Fibreoptic reflection oximetry allows continuous in-vivo estimation of jugular venous oxygen saturation. In combination with pulse oximetry the oxygen extraction ratio SaO2-SjO2/SaO2 can be derived enabling identification of states of global luxury perfusion, normal coupling of global cerebral blood flow with global cerebral metabolism, global cerebral hypoperfusion and global cerebral ischemia. Several technical difficulties may arise affecting the accuracy of SjO2 recordings which must be recognised by the clinician before medical intervention is contemplated.

[Pulse oximetry screening of critical congenital heart defects in the neonatal period. The Spanish National Neonatal Society recommendation].

PubMed

Sánchez Luna, Manuel; Pérez Muñuzuri, Alejandro; Sanz López, Ester; Leante Castellanos, José Luis; Benavente Fernández, Isabel; Ruiz Campillo, César W; Sánchez Redondo, M Dolores; Vento Torres, Máximo; Rite Gracia, Segundo

2018-02-01

Due to its severity, as well as the consequences of a late diagnosis, critical congenital heart defects (CCHD) represent a challenging situation, making an early diagnosis necessary and ideally before symptoms appear when circulatory collapse or death of the newborn can occur. Due to this, a prenatal and very early postnatal diagnosis is very important. Prenatal ultrasound screening and physical examination of the newborn can miss a considerable number of CCHD cases. Pulse oximetry screening has been demonstrated to be an effective, non-invasive, inexpensive, and well accepted tool in the early diagnosis of CCHD. The Spanish National Society of Neonatology, through its Standards Committee, and based on the current evidence, recommend the implementation of pulse oximetry screening of CCHD in Spain, and then to offer the best therapy possible to these newborn infants. Copyright © 2017 Asociación Española de Pediatría. Publicado por Elsevier España, S.L.U. All rights reserved.

Improving the detectability of oxygen saturation level targets for preterm neonates: A laboratory test of tremolo and beacon sonifications.

PubMed

Deschamps, Marie-Lys; Sanderson, Penelope; Hinckfuss, Kelly; Browning, Caitlin; Loeb, Robert G; Liley, Helen; Liu, David

2016-09-01

Recent guidelines recommend oxygen saturation (SpO2) levels of 90%-95% for preterm neonates on supplemental oxygen but it is difficult to discern such levels with current pulse oximetry sonifications. We tested (1) whether adding levels of tremolo to a conventional log-linear pulse oximetry sonification would improve identification of SpO2 ranges, and (2) whether adding a beacon reference tone to conventional pulse oximetry confuses listeners about the direction of change. Participants using the Tremolo (94%) or Beacon (81%) sonifications identified SpO2 range significantly more accurately than participants using the LogLinear sonification (52%). The Beacon sonification did not confuse participants about direction of change. The Tremolo sonification may have advantages over the Beacon sonification for monitoring SpO2 of preterm neonates, but both must be further tested with clinicians in clinically representative scenarios, and with different levels of ambient noise and distractions. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

A paramagnetic implant containing lithium naphthalocyanine microcrystals for high-resolution biological oximetry

PubMed Central

Meenakshisundaram, Guruguhan; Pandian, Ramasamy P.; Eteshola, Edward; Lee, Stephen C.; Kuppusamy, Periannan

2009-01-01

Lithium naphthalocyanine (LiNc) is a microcrystalline EPR oximetry probe with high sensitivity to oxygen (Pandian et al. J. Mater. Chem., 19, 4138, 2009). However, direct implantation of the crystals in the tissue for in vivo oxygen measurements may be hindered by concerns associated with their direct contact with the tissue/cells and loss of EPR signal due to particle migration in the tissue. In order to address these concerns, we have developed encapsulations (chips) of LiNc microcrystals in polydimethyl siloxane (PDMS), an oxygen-permeable, bioinert polymer. Oximetry evaluation of the fabricated chips revealed that the oxygen sensitivity of the crystals was unaffected by encapsulation in PDMS. Chips were stable against sterilization procedures or treatment with common biological oxidoreductants. In vivo oxygen measurements established the ability of the chips to provide reliable and repeated measurements of tissue oxygenation. This study establishes PDMS-encapsulated LiNc as a potential probe for long-term and repeated measurements of tissue oxygenation. PMID:20006529

A phantom with pulsating artificial vessels for non-invasive fetal pulse oximetry.

PubMed

Laqua, Daniel; Pollnow, Stefan; Fischer, Jan; Ley, Sebastian; Husar, Peter

2014-01-01

Arterial oxygen saturation of the fetus is an important parameter for monitoring its physical condition. During labor and delivery the transabdominal non-invasive fetal pulse oximetry could minimize the risk for mother and fetus, compared to other existing invasive examination methods. In this contribution, we developed a physical-like phantom to investigate new sensor circuits and algorithms of a non-invasive diagnostic method for fetal pulse oximetry. Hence, the developed artificial vascular system consists of two independent tube systems representing the maternal and fetal vessel system. The arterial blood pressure is reproduced with a pre-pressure and an artificial vascular system. Each pulse wave can be reproduced, by digital control of a proportional valve, adjustable viscoelastic elements, and resistances. The measurements are performed by pressure transducers, optical sensor units, and a coplanar capacitive sensor. Transmission and reflection measurements have shown that the fetal and maternal pulse waves can be reproduced qualitatively. The measured light represents the transabdominal modulated signal on an abdomen of a pregnant woman.

Continuous noninvasive monitoring in the neonatal ICU.

PubMed

Sahni, Rakesh

2017-04-01

Standard hemodynamic monitoring such as heart rate and systemic blood pressure may only provide a crude estimation of organ perfusion during neonatal intensive care. Pulse oximetry monitoring allows for continuous noninvasive monitoring of hemoglobin oxygenation and thus provides estimation of end-organ oxygenation. This review aims to provide an overview of pulse oximetry and discuss its current and potential clinical use during neonatal intensive care. Technological advances in continuous assessment of dynamic changes in systemic oxygenation with pulse oximetry during transition to extrauterine life and beyond provide additional details about physiological interactions among the key hemodynamic factors regulating systemic blood flow distribution along with the subtle changes that are frequently transient and undetectable with standard monitoring. Noninvasive real-time continuous systemic oxygen monitoring has the potential to serve as biomarkers for early-organ dysfunction, to predict adverse short-term and long-term outcomes in critically ill neonates, and to optimize outcomes. Further studies are needed to establish values predicting adverse outcomes and to validate targeted interventions to normalize abnormal values to improve outcomes.

How to develop a business case to establish a neonatal pulse oximetry programme for screening of congenital heart defects.

PubMed

Ewer, Andrew K

2012-12-01

Pulse oximetry screening for critical congenital heart defects (CCHDs) is a highly specific, moderately sensitive test which is cost effective, acceptable to both clinical staff and parents and meets the criteria for universal screening. Pulse oximetry screening is gaining considerable worldwide support and last year was added to the recommended uniform screening panel in the USA following endorsement by the Health and Human Services Secretary. There is significant heterogeneity in published screening protocols and it is important to consider all available evidence and also take local factors into account when developing a screening programme, whether it is within an individual hospital, neonatal network or even at a national level. This paper presents available options based both on the published evidence and personal practice experience which will aid those considering the introduction of screening to make the right decisions both from a clinical and financial perspective. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Utilization of Robotic Pets in Dementia Care.

PubMed

Petersen, Sandra; Houston, Susan; Qin, Huanying; Tague, Corey; Studley, Jill

2017-01-01

Behavioral problems may affect individuals with dementia, increasing the cost and burden of care. Pet therapy has been known to be emotionally beneficial for many years. Robotic pets have been shown to have similar positive effects without the negative aspects of traditional pets. Robotic pet therapy offers an alternative to traditional pet therapy. The study rigorously assesses the effectiveness of the PARO robotic pet, an FDA approved biofeedback device, in treating dementia-related symptoms. A randomized block design with repeated measurements guided the study. Before and after measures included reliable, valid tools such as: RAID, CSDD, GDS, pulse rate, pulse oximetry, and GSR. Participants interacted with the PARO robotic pet, and the control group received standard activity programs. Five urban secure dementia units comprised the setting. 61 patients, with 77% females, average 83.4 years in age, were randomized into control and treatment groups. Compared to the control group, RAID, CSDD, GSR, and pulse oximetry were increased in the treatment group, while pulse rate, pain medication, and psychoactive medication use were decreased. The changes in GSR, pulse oximetry, and pulse rate over time were plotted for both groups. The difference between groups was consistent throughout the 12-week study for pulse oximetry and pulse rate, while GSR had several weeks when changes were similar between groups. Treatment with the PARO robot decreased stress and anxiety in the treatment group and resulted in reductions in the use of psychoactive medications and pain medications in elderly clients with dementia.

The Utilization of Robotic Pets in Dementia Care

PubMed Central

Petersen, Sandra; Houston, Susan; Qin, Huanying; Tague, Corey; Studley, Jill

2016-01-01

Background: Behavioral problems may affect individuals with dementia, increasing the cost and burden of care. Pet therapy has been known to be emotionally beneficial for many years. Robotic pets have been shown to have similar positive effects without the negative aspects of traditional pets. Robotic pet therapy offers an alternative to traditional pet therapy. Objective: The study rigorously assesses the effectiveness of the PARO robotic pet, an FDA approved biofeedback device, in treating dementia-related symptoms. Methods: A randomized block design with repeated measurements guided the study. Before and after measures included reliable, valid tools such as: RAID, CSDD, GDS, pulse rate, pulse oximetry, and GSR. Participants interacted with the PARO robotic pet, and the control group received standard activity programs. Five urban secure dementia units comprised the setting. Results: 61 patients, with 77% females, average 83.4 years in age, were randomized into control and treatment groups. Compared to the control group, RAID, CSDD, GSR, and pulse oximetry were increased in the treatment group, while pulse rate, pain medication, and psychoactive medication use were decreased. The changes in GSR, pulse oximetry, and pulse rate over time were plotted for both groups. The difference between groups was consistent throughout the 12-week study for pulse oximetry and pulse rate, while GSR had several weeks when changes were similar between groups. Conclusions: Treatment with the PARO robot decreased stress and anxiety in the treatment group and resulted in reductions in the use of psychoactive medications and pain medications in elderly clients with dementia. PMID:27716673

Do adjunctive flap-monitoring technologies impact clinical decision making? An analysis of microsurgeon preferences and behavior by body region.

PubMed

Bellamy, Justin L; Mundinger, Gerhard S; Flores, José M; Wimmers, Eric G; Yalanis, Georgia C; Rodriguez, Eduardo D; Sacks, Justin M

2015-03-01

Multiple perfusion assessment technologies exist to identify compromised microvascular free flaps. The effectiveness, operability, and cost of each technology vary. The authors investigated surgeon preference and clinical behavior with several perfusion assessment technologies. A questionnaire was sent to members of the American Society for Reconstructive Microsurgery concerning perceptions and frequency of use of several technologies in varied clinical situations. Demographic information was also collected. Adjusted odds ratios were calculated using multinomial logistic regression accounting for clustering of similar practices within institutions/regions. The questionnaire was completed by 157 of 389 participants (40.4 percent response rate). Handheld Doppler was the most commonly preferred free flap-monitoring technology (56.1 percent), followed by implantable Doppler (22.9 percent) and cutaneous tissue oximetry (16.6 percent). Surgeons were significantly more likely to opt for immediate take-back to the operating room when presented with a concerning tissue oximetry readout compared with a concerning handheld Doppler signal (OR, 2.82; p < 0.01), whereas other technologies did not significantly alter postoperative management more than simple handheld Doppler. Clinical decision making did not significantly differ by demographics, training, or practice setup. Although most surgeons still prefer to use standard handheld Doppler for free flap assessment, respondents were significantly more likely to opt for immediate return to the operating room for a concerning tissue oximetry reading than an abnormal Doppler signal. This suggests that tissue oximetry may have the greatest impact on clinical decision making in the postoperative period.

Transcutaneous regional venous oximetry: a feasibility study.

PubMed

Thiele, Robert H; Tucker-Schwartz, Jason M; Lu, Yao; Gillies, George T; Durieux, Marcel E

2011-06-01

The arterial pulse oximeter, which was introduced clinically in the 1970s, is a convenient, useful, and now ubiquitous anesthesia monitor. Unfortunately, although percent saturation of arterial hemoglobin is, along with cardiac output and concentration of hemoglobin, one of 3 components of oxygen delivery, it does not indicate whether oxygen delivery to a region of interest is adequate. Knowledge of peripheral or regional venous oxygen saturation (Sxvo₂) may lend insight into analysis of regional oxygen supply and demand. Our goal was to assess the suitability of 3 anatomic sites for the transcutaneous assessment of Sxvo₂. Using a Nonin reflectance oximetry probe (provided by Nonin Medical, Plymouth, MN) placed directly over the antecubital, external jugular, and internal jugular veins in 10 volunteers, we measured the absorbance of red and infrared electromagnetic radiation. We performed fast Fourier transformation on these absorbance waveforms. The ratio of pulsatile absorbance of red and infrared radiation at different frequencies was compared with nonpulsatile absorption, and Sxvo₂ was calculated based on previously derived empiric correlations. Estimates of transcutaneous Sxvo₂ ranged from 41% to 97%, with mean values of 75%, 80%, and 80% at the antecubital, external jugular, and internal jugular veins, respectively. Overall, 93% of predicted Sxvo₂ values were < 90%. Validation and subsequent improvement of this technique requires correlation of our results with venous blood gas measurements, followed by incorporation of technologies from related fields in oximetry (fetal reflectance oximetry and near-infrared spectroscopy), as well as the development of advanced signal processing techniques.

Simulation of oxygen saturation measurement in a single blood vein.

PubMed

Duadi, Hamootal; Nitzan, Meir; Fixler, Dror

2016-09-15

The value of oxygen saturation in venous blood, SvO₂, has important clinical significance since it is related to the tissue oxygen utilization, which is related to the blood flow to the tissue and to its metabolism rate. However, existing pulse oximetry techniques are not suitable for blood in veins. In the current study we examine the feasibility of difference oximetry to assess SvO₂ by using two near-infrared wavelengths and collecting the backscattered light from two photodetectors located at different distances from the light source.

Respiratory rate and pulse oximetry derived information as predictors of hospital admission in young children in Bangladesh: a prospective observational study

PubMed Central

Garde, Ainara; Zhou, Guohai; Raihana, Shahreen; Dunsmuir, Dustin; Karlen, Walter; Dekhordi, Parastoo; Huda, Tanvir; Arifeen, Shams El; Larson, Charles; Kissoon, Niranjan; Dumont, Guy A; Ansermino, J Mark

2016-01-01

Objective Hypoxaemia is a strong predictor of mortality in children. Early detection of deteriorating condition is vital to timely intervention. We hypothesise that measures of pulse oximetry dynamics may identify children requiring hospitalisation. Our aim was to develop a predictive tool using only objective data derived from pulse oximetry and observed respiratory rate to identify children at increased risk of hospital admission. Setting Tertiary-level hospital emergency department in Bangladesh. Participants Children under 5 years (n=3374) presenting at the facility (October 2012–April 2013) without documented chronic diseases were recruited. 1-minute segments of pulse oximetry (photoplethysmogram (PPG), blood oxygen saturation (SpO2) and heart rate (HR)) and respiratory rate were collected with a mobile app. Primary outcome The need for hospitalisation based on expert physician review and follow-up. Methods Pulse rate variability (PRV) using pulse peak intervals of the PPG signal and features extracted from the SpO2 signal, all derived from pulse oximetry recordings, were studied. A univariate age-adjusted logistic regression was applied to evaluate differences between admitted and non-admitted children. A multivariate logistic regression model was developed using a stepwise selection of predictors and was internally validated using bootstrapping. Results Children admitted to hospital showed significantly (p<0.01) decreased PRV and higher SpO2 variability compared to non-admitted children. The strongest predictors of hospitalisation were reduced PRV-power in the low frequency band (OR associated with a 0.01 unit increase, 0.93; 95% CI 0.89 to 0.98), greater time spent below an SpO2 of 98% and 94% (OR associated with 10 s increase, 1.4; 95% CI 1.3 to 1.4 and 1.5; 95% CI 1.4 to 1.6, respectively), high respiratory rate, high HR, low SpO2, young age and male sex. These variables provided a bootstrap-corrected AUC of the receiver operating characteristic of 0.76. Conclusions Objective measurements, easily obtained using a mobile device in low-resource settings, can predict the need for hospitalisation. External validation will be required before clinical adoption. PMID:27534987

Nighttime oxygen desaturation and symptoms of sleep-disordered breathing in long-stay nursing home residents.

PubMed

Martin, Jennifer L; Mory, Aaron K; Alessi, Cathy A

2005-01-01

Sleep-disordered breathing (SDB) is common in older adults and has been implicated as a cause of decreased quality of life and even death. Sparse data exist on SDB in the nursing home setting. The authors evaluated SDB (using attended nocturnal pulse oximetry) in nursing home residents with daytime sleepiness and nighttime sleep disturbance. Pulse oximetry was used to estimate the prevalence of nighttime oxygen desaturation in 109 long-stay nursing home residents (mean [standard deviation] age = 86.2 [9.2] years; 74% women). Pulse oximetry findings were compared to a structured observational measurement of symptoms of SDB, the Observational Sleep Assessment Instrument. Seventy-one participants had concurrent wrist actigraphy to estimate total sleep time during oximetry recording. Using the oxygen desaturation index (ODI; average number of oxygen desaturations 4% or more below the baseline level per hour), the authors found that 40% of the residents had abnormal ODI (ODI more than 5, which is suggestive of SDB). Of all observational variables assessed, only loud breathing during sleep was significantly correlated with ODI (r =.284; p =.003). When ODI was adjusted for estimated total sleep time, higher adjusted ODI was associated with higher body mass index (kg/m(2)). Abnormal ODI is common in nursing home residents. Observed loud breathing at night and high body mass index may suggest that further assessment of SDB is indicated. Future research should determine the importance of SDB and abnormal nocturnal oxygen desaturation on functioning and quality of life in nursing home residents.

Domiciliary pulse-oximetry at exacerbation of chronic obstructive pulmonary disease: prospective pilot study

PubMed Central

2010-01-01

Background The ability to objectively differentiate exacerbations of chronic obstructive pulmonary disease (COPD) from day-to-day symptom variations would be an important development in clinical practice and research. We assessed the ability of domiciliary pulse oximetry to achieve this. Methods 40 patients with moderate-severe COPD collected daily data on changes in symptoms, heart-rate (HR), oxygen saturation (SpO2) and peak-expiratory flow (PEF) over a total of 2705 days. 31 patients had data suitable for baseline analysis, and 13 patients experienced an exacerbation. Data were expressed as multiples of the standard deviation (SD) observed from each patient when stable. Results In stable COPD, the SD for HR, SpO2 and PEF were approximately 5 min-1, 1% and 10l min-1. There were detectable changes in all three variables just prior to exacerbation onset, greatest 2-3 days following symptom onset. A composite Oximetry Score (mean magnitude of SpO2 fall and HR rise) distinguished exacerbation onset from symptom variation (area under receiver-operating characteristic curve, AUC = 0.832, 95%CI 0.735-0.929, p = 0.003). In the presence of symptoms, a change in Score of ≥1 (average of ≥1SD change in both HR and SpO2) was 71% sensitive and 74% specific for exacerbation onset. Conclusion We have defined normal variation of pulse oximetry variables in a small sample of patients with COPD. A composite HR and SpO2 score distinguished exacerbation onset from symptom variation, potentially facilitating prompt therapy and providing validation of such events in clinical trials. PMID:20961450

Critical congenital heart disease screening with a pulse oximetry in neonates.

PubMed

Hamilçıkan, Şahin; Can, Emrah

2018-02-23

To compare the results of pulse oximetry screening for critical congenital heart disease (CCHD) in newborn infants performed at <24 h and >24 h following. Measurements were taken for each group at <24 h and >24 h following birth. Echocardiography was performed if the SpO2 readings remained abnormal results. A total of 4518 newborns were included in this prospective descriptive study. Of these, 2484 (60.3%) were delivered vaginally and 1685 (39.7%) by cesarean section. Median time points of the screening were 25.4 (25.3-25.5) vs. 17.3 (12.2-22.4) hours after birth. In 4109 infants screened 24 h after birth, the mean pre- and postductal oxygen saturations (SpO2) were 96.5±1.99 and 97.7±1.98, while 127 infants screened within 24 h of mean preductal and postductal SpO2 were 91.33±2.64 and 94.0±4.44. No CCHD was detected during the study period. Pulse oximetry screening was false positive for CCHD in 9 of 4109 infants (0.02%); of these, six infants were referred to pediatric cardiology and three cases were diagnosed as other significant, non-cardiac pathology. There were two cases with AVSD (atrioventricular septal defect, three cases with ventricular septal defect (VSD), and one case with patent ductus arteriosus (PDA). Saturation values are different between <24-h and >24-h neonates in pulse oximetry screening. The screening in this study identified infants with other important pathologies, this forms an added value as an assessment tool for newborn infants.

Intraoperative colonic pulse oximetry in left-sided colorectal surgery: can it predict anastomotic leak?

PubMed

Salusjärvi, Johannes M; Carpelan-Holmström, Monika A; Louhimo, Johanna M; Kruuna, Olli; Scheinin, Tom M

2018-03-01

An anastomotic leak is a fairly common and a potentially lethal complication in colorectal surgery. Objective methods to assess the viability and blood circulation of the anastomosis could help in preventing leaks. Intraoperative pulse oximetry is a cheap, easy to use, fast, and readily available method to assess tissue viability. Our aim was to study whether intraoperative pulse oximetry can predict the development of an anastomotic leak. The study was a prospective single-arm study conducted between the years 2005 and 2011 in Helsinki University Hospital. Patient material consisted of 422 patients undergoing elective left-sided colorectal surgery. The patients were operated by one of the three surgeons. All of the operations were partial or total resections of the left side of the colon with a colorectal anastomosis. The intraoperative colonic oxygen saturation was measured with pulse oximetry from the colonic wall, and the values were analyzed with respect to post-operative complications. 2.3 times more operated anastomotic leaks occurred when the colonic StO 2 was ≤ 90% (11/129 vs 11/293). The mean colonic StO 2 was 91.1 in patients who developed an operated anastomotic leak and 93.0 in patients who did not. With logistic regression analysis, the risk of operated anastomotic leak was 4.2 times higher with StO 2 values ≤ 90%. Low intraoperative colonic StO 2 values are associated with the occurrence of anastomotic leak. Despite its handicaps, the method seems to be useful in assessing anastomotic viability.

Evaluating the diagnostic gap: statewide incidence of undiagnosed critical congenital heart disease before newborn screening with pulse oximetry.

PubMed

Mouledoux, Jessica H; Walsh, William F

2013-10-01

Screening for critical congenital heart disease (CCHD) using pulse oximetry has been endorsed by the American Academy of Pediatrics and the American Heart Association. We sought to determine the incidence of undetected CCHD in Tennessee and the diagnostic gap of CCHD in Middle Tennessee prior to screening implementation. The Tennessee Initiative for Perinatal Quality Care (TIPQC) Undetected CCHD Registry is a quality improvement initiative established to identify neonates discharged from the nursery with undetected CCHD. The TIPQC database was queried and a simultaneous review of all neonates with CCHD in the Middle Tennessee region was performed to define the incidence and identify the pre-screen diagnostic gap of undetected CCHD at the time of hospital discharge. In 2011, of 79,462 live births in Tennessee, 12 newborns had undiagnosed CCHD (incidence 15 per 100,000; 95 % CI 9-26 per 100,000). Nine of 12 (75 %) had coarctation of the aorta (CoA). There were no deaths due to undiagnosed CCHD. In the Middle Tennessee region, 6 of 45 neonates with CCHD were missed, for a diagnostic gap of 13 % (95 % CI 6-26 %). Prior to implementation of CCHD screening using pulse oximetry, 12 Tennessee neonates with CCHD were missed by prenatal ultrasound and newborn examination. CoA was the most common lesion missed and is also the CCHD most likely to be missed despite addition of screening using pulse oximetry. Continued evaluation of the diagnostic gap with particular attention to missed diagnoses of CoA should accompany institution of CCHD screening programs.

Assessing diabetic foot ulcer development risk with hyperspectral tissue oximetry

NASA Astrophysics Data System (ADS)

Yudovsky, Dmitry; Nouvong, Aksone; Schomacker, Kevin; Pilon, Laurent

2011-02-01

Foot ulceration remains a serious health concern for diabetic patients and has a major impact on the cost of diabetes treatment. Early detection and preventive care, such as offloading or improved hygiene, can greatly reduce the risk of further complications. We aim to assess the use of hyperspectral tissue oximetry in predicting the risk of diabetic foot ulcer formation. Tissue oximetry measurements are performed during several visits with hyperspectral imaging of the feet in type 1 and 2 diabetes mellitus subjects that are at risk for foot ulceration. The data are retrospectively analyzed at 21 sites that ulcerated during the course of our study and an ulceration prediction index is developed. Then, an image processing algorithm based on this index is implemented. This algorithm is able to predict tissue at risk of ulceration with a sensitivity and specificity of 95 and 80%, respectively, for images taken, on average, 58 days before tissue damage is apparent to the naked eye. Receiver operating characteristic analysis is also performed to give a range of sensitivity/specificity values resulting in a Q-value of 89%.

Pulse oximeter accuracy and precision at five different sensor locations in infants and children with cyanotic heart disease

PubMed Central

Das, Jyotirmoy; Aggarwal, Amit; Aggarwal, Naresh Kumar

2010-01-01

Since the invention of pulse oximetry by Takuo Aoyagi in the early 1970s, its use has expanded beyond the perioperative care into neonatal, paediatric and adult intensive care units (ICUs). Pulse oximetry is one of the most important advances in respiratory monitoring as its readings (SpO2) are used clinically as an indirect estimation of arterial oxygen saturation (SaO2). Sensors were placed frequently on the sole, palm, ear lobe or toes in addition to finger. On performing an extensive Medline search using the terms “accuracy of pulse oximetry” and “precision of pulse oximetry”, limited data were found in congenital heart disease patients in the immediate post-corrective stage. Also, there are no reports and comparative data of the reliability and precision of pulse oximetry when readings from five different sensor locations (viz. finger, palm, toe, sole and ear) are analysed simultaneously. To fill these lacunae of knowledge, we undertook the present study in 50 infants and children with cyanotic heart disease in the immediate post-corrective stage. PMID:21224970

Application of NIR laser diodes to pulse oximetry

NASA Astrophysics Data System (ADS)

Lopez Silva, Sonnia M.; Giannetti, Romano; Dotor, Maria L.; Sendra, Jose R.; Silveira, Juan P.; Briones, Fernando

1999-01-01

A transmittance pulse oximeter based on near-infrared laser diodes for monitoring arterial blood hemoglobin oxygen saturation has been developed and tested. The measurement system consists of the optical sensor, sensor electronics, acquisition board and personal computer. The system has been tested in a two-part experimental study involving human volunteers. A calibration curve was derived and healthy volunteers were monitored under normal and apnea conditions, both with the proposed system and with a commercial pulse oximeter. The obtained results demonstrate the feasibility of using a sensor with laser diodes emitting at specific near-infrared wavelengths for pulse oximetry.

Evaluation of Candidate Measures for Home-Based Screening of Sleep Disordered Breathing in Taiwanese Bus Drivers

PubMed Central

Ting, Hua; Huang, Ren-Jing; Lai, Ching-Hsiang; Chang, Shen-Wen; Chung, Ai-Hui; Kuo, Teng-Yao; Chang, Ching-Haur; Shih, Tung-Sheng; Lee, Shin-Da

2014-01-01

Background: Sleepiness-at-the-wheel has been identified as a major cause of highway accidents. The aim of our study is identifying the candidate measures for home-based screening of sleep disordered breathing in Taiwanese bus drivers, instead of polysomnography. Methods: Overnight polysomnography accompanied with simultaneous measurements of alternative screening devices (pulse oximetry, ApneaLink, and Actigraphy), heart rate variability, wake-up systolic blood pressure and questionnaires were completed by 151 eligible participants who were long-haul bus drivers with a duty period of more than 12 h a day and duty shifting. Results: 63.6% of professional bus drivers were diagnosed as having sleep disordered breathing and had a higher body mass index, neck circumference, systolic blood pressure, arousal index and desaturation index than those professional bus drivers without evidence of sleep disordered breathing. Simple home-based candidate measures: (1) Pulse oximetry, oxygen-desaturation indices by ≥3% and 4% (r = 0.87∼0.92); (2) Pulse oximetry, pulse-rising indices by ≥7% and 8% from a baseline (r = 0.61∼0.89); and (3) ApneaLink airflow detection, apnea-hypopnea indices (r = 0.70∼0.70), based on recording-time or Actigraphy-corrected total sleep time were all significantly correlated with, and had high agreement with, corresponding polysomnographic apnea-hypopnea indices [(1) 94.5%∼96.6%, (2) 93.8%∼97.2%, (3) 91.1%∼91.3%, respectively]. Conversely, no validities of SDB screening were found in the multi-variables apnea prediction questionnaire, Epworth Sleepiness Scale, night-sleep heart rate variability, wake-up systolic blood pressure and anthropometric variables. Conclusions: The indices of pulse oximetry and apnea flow detection are eligible criteria for home-based screening of sleep disordered breathing, specifically for professional drivers. PMID:24803198

Evaluating cost and resource use associated with pulse oximetry screening for critical congenital heart disease: Empiric estimates and sources of variation.

PubMed

Reeder, Matthew R; Kim, Jaewhan; Nance, Amy; Krikov, Sergey; Feldkamp, Marcia L; Randall, Harper; Botto, Lorenzo D

2015-11-01

Newborn screening for critical congenital heart disease (CCHD) using pulse oximetry is being implemented in the United States and internationally; however, few data are available on the associated in-hospital costs and use of resources. Time and motion study in well-baby nurseries at two large urban hospitals in Utah using different approaches to pulse oximetry screening. Two observers recorded the time for each screening step together with provider and equipment characteristics. Structured questionnaire provided additional information on labor and equipment costs. Fifty-three CCHD screens were observed. At site A (n = 22), screening was mostly done by medical assistants (95%) using disposable probes (100%); at site B (n = 31), screening was mostly performed by certified nursing assistants (90%) using reusable probes (90%). Considering only first screens (n = 53), the median screen time was 8.6 min (range: 3.2-23.2), with no significant difference between sites. The overall cost ($ in 2014) of screening per baby was $24.52 at site A and $2.60 at site B. Nearly all the variation in cost (90%) was due to the cost of disposable probes; labor costs were similar between sites. CCHD screening by means of pulse oximetry is reasonably fast for most babies, leading to relative small labor costs with little variation by provider type. The main driver of costs is equipment: in a high throughput setting, reusable probes are currently associated with considerable cost saving compared with disposable probes. As programs expand to universal screening, improved and cheaper technologies could lead to considerable economies of scale. © 2015 Wiley Periodicals, Inc.

Using India Ink as a Sensor for Oximetry: Evidence of its Safety as a Medical Device.

PubMed

Flood, Ann Barry; Wood, Victoria A; Swartz, Harold M

2017-01-01

Clinical EPR spectroscopy is emerging as an important modality, with the potential to be used in standard clinical practice to determine the extent of hypoxia in tissues and whether hypoxic tissues respond to breathing enriched oxygen during therapy. Oximetry can provide important information useful for prognosis and to improve patient outcomes. EPR oximetry has many potential advantages over other ways to measure oxygen in tissues, including directly measuring oxygen in tissues and being particularly sensitive to low oxygen, repeatable, and non-invasive after an initial injection of the EPR-sensing material is placed in the tumor. The most immediately available oxygen sensor is India ink, where two classes of carbon (carbon black and charcoal) have been identified as having acceptable paramagnetic properties for oximetry. While India ink has a long history of safe use in tattoos, a systematic research search regarding its safety for marking tissues for medical uses and an examination of the evidence that differentiates between ink based on charcoal or carbon black has not been conducted. Using systematic literature search techniques, we searched the PubMed and Food and Drug Administration databases, finding ~1000 publications reporting on adverse events associated with India/carbon based inks. The detailed review of outcomes was based on studies involving >16 patients, where the ink was identifiable as carbon black or charcoal. Fifty-six studies met these criteria. There were few reports of complications other than transient and usually mild discomfort and bleeding at injection, and there was no difference in charcoal vs. carbon black India ink. India ink was generally well tolerated by patients and physicians reported that it was easy to use in practice and used few resources. The risk is low enough to justify its use as an oxygen sensor in clinical practice.

Cerebral Oxygenation of the Cortex and Striatum following Normobaric Hyperoxia and Mild Hypoxia in Rats by EPR Oximetry using Multi-Probe Implantable Resonators

PubMed Central

Hou, Huagang; Li, Hongbin; Dong, Ruhong; Mupparaju, Sriram; Khan, Nadeem; Swartz, Harold

2013-01-01

Multi-site electron paramagnetic resonance (EPR) oximetry, using multi-probe implantable resonators, was used to measure the partial pressure of oxygen (pO2) in the brains of rats following normobaric hyperoxia and mild hypoxia. The cerebral tissue pO2 was measured simultaneously in the cerebral cortex and striatum in the same rats before, during, and after normobaric hyperoxia and mild hypoxia challenges. The baseline mean tissue pO2 values (±SE) were not significantly different between the cortex and striatum. During 30 min of 100% O2 inhalation, a statistically significant increase in tissue pO2 of all four sites was observed, however, the tissue pO2 of the striatum area was significantly higher than in the forelimb area of the cortex. Brain pO2 significantly decreased from the baseline value during 15 min of 15% O2 challenge. No differences in the recovery of the cerebral cortex and striatum pO2 were observed when the rats were allowed to breathe 30% O2. It appears that EPR oximetry using implantable resonators can provide information on pO2 under the experimental conditions needed for such a study. The levels of pO2 that occurred in these experiments are readily resolvable by multi-site EPR oximetry with multi-probe resonators. In addition, the ability to simultaneously measure the pO2 in several areas of the brain provides important information that could potentially help differentiate the pO2 changes that can occur due to global or local mechanisms. PMID:21445770

Real-time monitoring of ischemic and contralateral brain pO2 during stroke by variable length multisite resonators

PubMed Central

Hou, Huagang; Li, Hongbin; Dong, Ruhong; Khan, Nadeem; Swartz, Harold

2014-01-01

Purpose Electron paramagnetic resonance (EPR) oximetry using variable length multi-probe implantable resonator (IR), was used to investigate the temporal changes in the ischemic and contralateral brain pO2 during stroke in rats. Material and Methods The EPR signal to noise ratio (S/N) of the IR with four sensor loops at a depth of up to11 mm were compared with direct implantation of lithium phthalocyanine (LiPc, oximetry probe) deposits in vitro. These IRs were used to follow the temporal changes in pO2 at two sites in each hemisphere during ischemia induced by left middle cerebral artery occlusion (MCAO) in rats breathing 30% O2 or 100% O2. Results The S/N ratios of the IRs were significantly greater than the LiPc deposits. A similar pO2 at two sites in each hemisphere prior to the onset of ischemia was observed in rats breathing 30% O2. However, a significant decline in the pO2 of the left cortex and striatum occurred during ischemia but no change in the pO2 of the contralateral brain was observed. A significant increase in the pO2 of only the contralateral non-ischemic brain was observed in the rats breathing 100% O2. No significant difference in the infarct volume was evident between the animals breathing 30% O2 or 100% O2 during ischemia. Conclusions EPR oximetry with IRs can repeatedly assess temporal changes in the brain pO2 at four sites simultaneously during stroke. This oximetry approach can be used to test and develop interventions to rescue ischemic tissue by modulating cerebral pO2 during stroke. PMID:24629514

Dynamic changes in oxygenation of intracranial tumor and contralateral brain during tumor growth and carbogen breathing: A multisite EPR oximetry with implantable resonators

PubMed Central

Hou, Huagang; Dong, Ruhong; Li, Hongbin; Williams, Benjamin; Lariviere, Jean P.; Hekmatyar, S.K.; Kauppinen, Risto A.; Khan, Nadeem; Swartz, Harold

2013-01-01

Introduction Several techniques currently exist for measuring tissue oxygen; however technical difficulties have limited their usefulness and general application. We report a recently developed electron paramagnetic resonance (EPR) oximetry approach with multiple probe implantable resonators (IRs) that allow repeated measurements of oxygen in tissue at depths of greater than 10 mm. Methods The EPR signal to noise (S/N) ratio of two probe IRs was compared with that of LiPc deposits. The feasibility of intracranial tissue pO2 measurements by EPR oximetry using IRs was tested in normal rats and rats bearing intracerebral F98 tumors. The dynamic changes in the tissue pO2 were assessed during repeated hyperoxia with carbogen breathing. Results A 6–10 times increase in the S/N ratio was observed with IRs as compared to LiPc deposits. The mean brain pO2 of normal rats was stable and increased significantly during carbogen inhalation in experiments repeated for 3 months. The pO2 of F98 glioma declined gradually, while the pO2 of contralateral brain essentially remained the same. Although a significant increase in the glioma pO2 was observed during carbogen inhalation, this effect declined in experiments repeated over days. Conclusion EPR oximetry with IRs provides a significant increase in S/N ratio. The ability to repeatedly assess orthotopic glioma pO2 is likely to play a vital role in understanding the dynamics of tissue pO2 during tumor growth and therapies designed to modulate tumor hypoxia. This information could then be used to optimize chemoradiation by scheduling treatments at times of increased glioma oxygenation. PMID:22033225

Pulse oximetry recorded from the Phone Oximeter for detection of obstructive sleep apnea events with and without oxygen desaturation in children.

PubMed

Garde, Ainara; Dehkordi, Parastoo; Wensley, David; Ansermino, J Mark; Dumont, Guy A

2015-01-01

Obstructive sleep apnea (OSA) disrupts normal ventilation during sleep and can lead to serious health problems in children if left untreated. Polysomnography, the gold standard for OSA diagnosis, is resource intensive and requires a specialized laboratory. Thus, we proposed to use the Phone Oximeter™, a portable device integrating pulse oximetry with a smartphone, to detect OSA events. As a proportion of OSA events occur without oxygen desaturation (defined as SpO2 decreases ≥ 3%), we suggest combining SpO2 and pulse rate variability (PRV) analysis to identify all OSA events and provide a more detailed sleep analysis. We recruited 160 children and recorded pulse oximetry consisting of SpO2 and plethysmography (PPG) using the Phone Oximeter™, alongside standard polysomnography. A sleep technician visually scored all OSA events with and without oxygen desaturation from polysomnography. We divided pulse oximetry signals into 1-min signal segments and extracted several features from SpO2 and PPG analysis in the time and frequency domain. Segments with OSA, especially the ones with oxygen desaturation, presented greater SpO2 variability and modulation reflected in the spectral domain than segments without OSA. Segments with OSA also showed higher heart rate and sympathetic activity through the PRV analysis relative to segments without OSA. PRV analysis was more sensitive than SpO2 analysis for identification of OSA events without oxygen desaturation. Combining SpO2 and PRV analysis enhanced OSA event detection through a multiple logistic regression model. The area under the ROC curve increased from 81% to 87%. Thus, the Phone Oximeter™ might be useful to monitor sleep and identify OSA events with and without oxygen desaturation at home.

Motion resistant pulse oximetry in neonates

PubMed Central

Sahni, R; Gupta, A; Ohira-Kist, K; Rosen, T

2003-01-01

Background: Pulse oximetry is widely used in neonates. However, its reliability is often affected by motion artefact. Clinicians confronted with questionable oxygen saturation (SpO2) values often estimate the reliability by correlating heart rate (HR) obtained with the oximeter with that obtained by electrocardiogram. Objective: To compare the effects of motion on SpO2 and HR measurements made with Masimo signal extraction technology and those made with a Nellcor N-200. Design: Continuous pulse oximetry and HR monitoring were performed in 15 healthy, term infants (mean (SD) birth weight 3408 (458) g) undergoing circumcision, using Masimo and Nellcor pulse oximeters and a standard HR monitor (Hewlett-Packard). Simultaneous minute by minute behavioural activity codes were also assigned. Baseline data were collected for 10 minutes when the infant was quietly asleep and then continued during and after circumcision for a total duration of one hour. The oximeter HR and SpO2 values were compared and related to HR values obtained by ECG during all three periods. The effect of behavioural activity on SpO2 and HR was also evaluated. Results: When compared with results obtained with the Nellcor, the mean SpO2 and HR were higher and the incidence of artefact lower with the Masimo during all three periods. Masimo HR more accurately predicted HR obtained with a standard monitor, with lower residual error. SpO2 and HR values obtained with the Nellcor were lower and more variable during all behavioural states, especially crying, when excessive motion artefact was most likely. Conclusions: The data suggest that Masimo signal extraction technology may offer improvement in pulse oximetry performance, particularly in clinical situations in which extreme motion artefacts are likely. PMID:14602699

A theoretical model for optical oximetry at the capillary-level by optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Liu, Rongrong; Spicer, Graham; Chen, Siyu; Zhang, Hao F.; Yi, Ji; Backman, Vadim

2017-02-01

Oxygen saturation (sO2) of RBCs in capillaries can indirectly assess local tissue oxygenation and metabolic function. For example, the altered retinal oxygenation in diabetic retinopathy and local hypoxia during tumor development in cancer are reflected by abnormal sO2 of local capillary networks. However, it is far from clear whether accurate label-free optical oximetry (i.e. measuring hemoglobin sO2) is feasible from dispersed red blood cells (RBCs) at the single-capillary level. The sO2-dependent hemoglobin absorption contrast present in optical scattering signal is complicated by geometry-dependent scattering from RBCs. Here we provide a theoretical model to calculate the backscattering spectra of single RBCs based on the first-order Born approximation, considering the orientation, size variation, and deformation of RBCs. We show that the oscillatory spectral behavior of RBC geometries is smoothed by variations in cell size and orientation, resulting in clear sO2-dependent spectral contrast. In addition, this spectral contrast persists with different deformations of RBCs, allowing the sO2 of individual RBCs in capillaries to be characterized. The theoretical model is verified by Mie theory and experiments using visible light optical coherence tomography (vis-OCT). Thus, this study shows for the first time the feasibility of, and provides a theoretical model for, label-free optical oximetry at the single-capillary level by backscattering-based imaging modalities, challenging the popular view that such measurements are impossible at the single-capillary level. This is promising for in vivo backscattering-based optical oximetry at the single-capillary level, to measure local capillary sO2 for early diagnosis, progression monitoring, and treatment evaluation of diabetic retinopathy and cancer.

A retrospective analysis of the effect of blood transfusion on cerebral oximetry entropy and acute kidney injury.

PubMed

Engoren, Milo; Brown, Russell R; Dubovoy, Anna

2017-01-01

Acute anemia is associated with both cerebral dysfunction and acute kidney injury and is often treated with red blood cell transfusion. We sought to determine if blood transfusion changed the cerebral oximetry entropy, a measure of the complexity or irregularity of the oximetry values, and if this change was associated with subsequent acute kidney injury. This was a retrospective, case-control study of patients undergoing cardiac surgery with cardiopulmonary bypass at a tertiary care hospital, comparing those who received a red blood cell transfusion to those who did not. Acute kidney injury was defined as a perioperative increase in serum creatinine by ⩾26.4 μmol/L or by ⩾50% increase. Entropy was measured using approximate entropy, sample entropy, forbidden word entropy and basescale4 entropy in 500-point sets. Forty-four transfused patients were matched to 88 randomly selected non-transfused patients. All measures of entropy had small changes in the transfused group, but increased in the non-transfused group (p<0.05, for all comparisons). Thirty-five of 132 patients (27%) suffered acute kidney injury. Based on preoperative factors, patients who suffered kidney injury were similar to those who did not, including baseline cerebral oximetry levels. After analysis with hierarchical logistic regression, the change in basescale4 entropy (odds ratio = 1.609, 95% confidence interval = 1.057-2.450, p = 0.027) and the interaction between basescale entropy and transfusion were significantly associated with subsequent development of acute kidney injury. The transfusion of red blood cells was associated with a smaller rise in entropy values compared to non-transfused patients, suggesting a change in the regulation of cerebral oxygenation, and these changes in cerebral oxygenation are also associated with acute kidney injury.

Opportunities and barriers in paediatric pulse oximetry for pneumonia in low-resource clinical settings: a qualitative evaluation from Malawi and Bangladesh

PubMed Central

Boyd, Nicholas; Walker, Isabeau; Zadutsa, Beatiwel; Baqui, Abdullah H; Ahmed, Salahuddin; Islam, Mazharul; Kainja, Esther; Nambiar, Bejoy; Wilson, Iain; McCollum, Eric D

2018-01-01

Objective To gain an understanding of what challenges pulse oximetry for paediatric pneumonia management poses, how it has changed service provision and what would improve this device for use across paediatric clinical settings in low-income countries. Design Focus group discussions (FGDs), with purposive sampling and thematic analysis using a framework approach. Setting Community, front-line outpatient, and hospital outpatient and inpatient settings in Malawi and Bangladesh, which provide paediatric pneumonia care. Participants Healthcare providers (HCPs) from Malawi and Bangladesh who had received training in pulse oximetry and had been using oximeters in routine paediatric care, including community healthcare workers, non-physician clinicians or medical assistants, and hospital-based nurses and doctors. Results We conducted six FGDs, with 23 participants from Bangladesh and 26 from Malawi. We identified five emergent themes: trust, value, user-related experience, sustainability and design. HCPs discussed the confidence gained through the use of oximeters, resulting in improved trust from caregivers and valuing the device, although there were conflicts between the weight given to clinical judgement versus oximeter results. HCPs reported the ease of using oximeters, but identified movement and physically smaller children as measurement challenges. Challenges in sustainability related to battery durability and replacement parts, however many HCPs had used the same device longer than 4 years, demonstrating robustness within these settings. Desirable features included back-up power banks and integrated respiratory rate and thermometer capability. Conclusions Pulse oximetry was generally deemed valuable by HCPs for use as a spot-check device in a range of paediatric low-income clinical settings. Areas highlighted as challenges by HCPs, and therefore opportunities for redesign, included battery charging and durability, probe fit and sensitivity in paediatric populations. Trial registration number NCT02941237. PMID:29382679

Evaluation of peripheral microcirculation improvement of foot after tarsal tunnel release in diabetic patients by transcutaneous oximetry.

PubMed

Trignano, Emilio; Fallico, Nefer; Chen, Hung-Chi; Faenza, Mario; Bolognini, Alfonso; Armenti, Andrea; Santanelli Di Pompeo, Fabio; Rubino, Corrado; Campus, Gian Vittorio

2016-01-01

According to recent studies, peripheral nerve decompression in diabetic patients seems to not only improve nerve function, but also to increase microcirculation; thus decreasing the incidence of diabetic foot wounds and amputations. However, while the postoperative improvement of nerve function is demonstrated, the changes in peripheral microcirculation have not been demonstrated yet. The aim of this study is to assess the degree of microcirculation improvement of foot after the tarsal tunnel release in the diabetic patients by using transcutaneous oximetry. Twenty diabetic male patients aged between 43 and 72 years old (mean age 61.2 years old) suffering from diabetic peripheral neuropathy with superimposed nerve compression underwent transcutaneous oximetry (PtcO2) before and after tarsal tunnel release by placing an electrode on the skin at the level of the dorsum of the foot. Eight lower extremities presented diabetic foot wound preoperatively. Thirty-six lower extremities underwent surgical release of the tibialis posterior nerve only, whereas four lower extremities underwent the combined release of common peroneal nerve, anterior tibialis nerve, and posterior tibialis nerve. Preoperative values of transcutaneous oximetry were below the critical threshold, that is, lower than 40 mmHg (29.1 ± 5.4 mmHg). PtcO2 values at one month after surgery (45.8 ± 6.4 mmHg) were significantly higher than the preoperative ones (P = 0.01). The results of postoperative increase in PtcO2 values demonstrate that the release of the tarsal tunnel determines a relevant increase in microcirculation in the feet of diabetic patients. © 2015 Wiley Periodicals, Inc.

Accuracy of noninvasive multiwave pulse oximetry compared with carboxyhemoglobin from blood gas analysis in unselected emergency department patients.

PubMed

Roth, Dominik; Herkner, Harald; Schreiber, Wolfgang; Hubmann, Nina; Gamper, Gunnar; Laggner, Anton N; Havel, Christof

2011-07-01

Accurate and timely diagnosis of carbon monoxide (CO) poisoning is difficult because of nonspecific symptoms. Multiwave pulse oximetry might facilitate the screening for occult poisoning by noninvasive measurement of carboxyhemoglobin (COHb), but its reliability is still unknown. We assess bias and precision of COHb oximetry compared with the criterion standard blood gas analysis. This was a prospective diagnostic accuracy study according to STARD (Standards for the Reporting of Diagnostic accuracy studies) criteria, performed at a tertiary care hospital emergency department. We included all patients for whom both invasive and noninvasive measurement within 60 minutes was available, regardless of their complaints, during a 1-year period. One thousand five hundred seventy-eight subjects were studied, of whom 17 (1.1%) received a diagnosis of CO poisoning. In accordance with this limited patient cohort, we found a bias of 2.99% COHb (1.50% for smokers, 4.33% for nonsmokers) and a precision of 3.27% COHb (2.90% for smokers, 2.98% for nonsmokers), limits of agreement from -3.55% to 9.53% COHb (-4.30% to 7.30% for smokers, -1.63% to 10.29% for nonsmokers). Upper limit of normal cutoff of 6.6% COHb had the highest sensitivity in screening for CO poisoning. Smoking status and COHb level had the most influence on the deviation between measurements. Multiwave pulse oximetry was found to measure COHb with an acceptable bias and precision. These results suggest it can be used to screen large numbers of patients for occult CO poisoning. Copyright © 2011 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

Impact of extracranial contamination on regional cerebral oxygen saturation: a comparison of three cerebral oximetry technologies.

PubMed

Davie, Sophie N; Grocott, Hilary P

2012-04-01

Cerebral oximetry is a noninvasive technology using near-infrared spectroscopy (NIRS) to estimate regional cerebral oxygen saturation. Although NIRS cerebral oximetry is being increasingly used in many clinical settings, interdevice technologic differences suggest potential variation in the ability to accurately acquire brain oxygenation signals. The primary objective of this study was to determine if NIRS-derived regional cerebral oxygen saturation measurements accurately account for oxygen saturation contamination from extracranial tissue. Twelve healthy volunteers had each of three NIRS devices (FORE-SIGHT [CAS Medical Systems Inc; Brandford, CT], INVOS 5100C-PB [Covidien; Boulder, CO], and EQUANOX Classic 7600 [Nonin Medical Inc; Plymouth, MN]) randomly applied to the forehead. After this, a circumferential pneumatic head cuff was positioned such that when inflated, hypoxia-ischemia would be produced in the extracranial scalp tissue beneath the NIRS cerebral oximeters. Comparisons among the three devices were made of the NIRS measurements before and following hypoxia-ischemia produced in the scalp tissue with inflation of the head cuff. The induction of extracranial hypoxia-ischemia resulted in a significant reduction in regional cerebral oxygen saturation measurements in all three NIRS devices studied. At 5 min postinflation of the pneumatic head cuff, the INVOS demonstrated a 16.6 ± 9.6% (mean ± SD) decrease from its baseline (P = 0.0001), the FORE-SIGHT an 11.8 ± 5.3% decrease from its baseline (P < 0.0001), and the EQUANOX a 6.8 ± 6.0% reduction from baseline (P = 0.0025). Extracranial contamination appears to significantly affect NIRS measurements of cerebral oxygen saturation. Although the clinical implications of these apparent inaccuracies require further study, they suggest that the oxygen saturation measurements provided by cerebral oximetry do not solely reflect that of the brain alone.

Assessment of clinical application of pulse oximetry probes in llamas and alpacas.

PubMed

Grubb, Tamara L; Anderson, David E

2017-08-01

The placement and accuracy of pulse oximeter probes can vary markedly among species. For our study, we aimed to assess the accuracy of pulse oximetry and to determine the most clinically useful sites for probe placement in llamas and alpacas. The objectives included an analysis of pulse oximetry probes for accurate assessment of llamas and alpacas and to determine the best placement of the probes to achieve accurate readings. For study 1, saturation of haemoglobin with oxygen was measured in 184 arterial blood gas samples (SaO 2 ) using a co-oximeter and compared to saturation of haemoglobin with oxygen simultaneously measured using a pulse oximeter (S p O 2 ). The bias and precision for the SpO 2 -S a O 2 difference was calculated and plotted on a Bland-Altman plot. For study 2, S p O 2 data was collected 624 times from a variety of sites [tongue (T), nasal septum (NS), lip (L), vulva (V), prepuce (P), ear (E), and scrotum (S)] and recorded based upon a percentage of successful readings. Results for study 1 revealed that S p O 2 was consistently 0 to -6% points different than S a O 2 . The bias and precision of the S p O 2 -S a O 2 difference was -2.6 ± 1.7%. Results for study 2 uncovered that 540 recordings were successful readings and were obtained from the tongue and nasal septum with 97% accuracy, the lip 80%, vulva 62%, prepuce 59%, ear and scrotum < 50%. We concluded that pulse oximetry probes provide reliable estimates of arterial haemoglobin oxygen saturation in llamas and alpacas and is most accurately read when placed on the nasal septum or tongue.

Calibration of Contactless Pulse Oximetry

PubMed Central

Bartula, Marek; Bresch, Erik; Rocque, Mukul; Meftah, Mohammed; Kirenko, Ihor

2017-01-01

BACKGROUND: Contactless, camera-based photoplethysmography (PPG) interrogates shallower skin layers than conventional contact probes, either transmissive or reflective. This raises questions on the calibratability of camera-based pulse oximetry. METHODS: We made video recordings of the foreheads of 41 healthy adults at 660 and 840 nm, and remote PPG signals were extracted. Subjects were in normoxic, hypoxic, and low temperature conditions. Ratio-of-ratios were compared to reference Spo2 from 4 contact probes. RESULTS: A calibration curve based on artifact-free data was determined for a population of 26 individuals. For an Spo2 range of approximately 83% to 100% and discarding short-term errors, a root mean square error of 1.15% was found with an upper 99% one-sided confidence limit of 1.65%. Under normoxic conditions, a decrease in ambient temperature from 23 to 7°C resulted in a calibration error of 0.1% (±1.3%, 99% confidence interval) based on measurements for 3 subjects. PPG signal strengths varied strongly among individuals from about 0.9 × 10−3 to 4.6 × 10−3 for the infrared wavelength. CONCLUSIONS: For healthy adults, the results present strong evidence that camera-based contactless pulse oximetry is fundamentally feasible because long-term (eg, 10 minutes) error stemming from variation among individuals expressed as A*rms is significantly lower (<1.65%) than that required by the International Organization for Standardization standard (<4%) with the notion that short-term errors should be added. A first illustration of such errors has been provided with A**rms = 2.54% for 40 individuals, including 6 with dark skin. Low signal strength and subject motion present critical challenges that will have to be addressed to make camera-based pulse oximetry practically feasible. PMID:27258081

Combined pulse-oximeter-NIRS system for biotissue diagnostics

NASA Astrophysics Data System (ADS)

Hovhannisyan, Vladimir A.

2005-08-01

Multi-wavelength (670, 805, 848 and 905 nm), multi-detector device for non-invasive measurement of biochemical components concentration in human or animal tissues, combining the methods of conventional pulse-oximetry and near infrared spectroscopy, is developed. The portable and clinically applicable system allows to measure heart pulse rate, oxygen saturation of arterial hemoglobin (pulse-oximetry method) and local absolute concentration of oxyhemoglobin, deoxyhemoglobin and oxidized cytochrome aa3 or other IR absorbed compounds (NIRS method). The system can be applied in monitoring of oxygen availability and utilization by the brain in neonatal and adults, neuro- traumatology, intensive care medicine, transplantation and plastic surgery, in sport, high-altitude and aviation medicine.

A finger-free wrist-worn pulse oximeter for the monitoring of chronic obstructive pulmonary disease

NASA Astrophysics Data System (ADS)

Chu, Chang-Sheng; Chuang, Shuang-Chao; Lee, Yeh Wen; Fan, Chih-Hsun; Chung, Lung Pin; Li, Yu-Tang; Chen, Jyh-Chern

2016-03-01

Herein, a finger-free wrist-worn pulse oximeter is presented. This device allows patients to measure blood oxygen level and pulse rate without hindering their normal finger movement. This wrist-worn pulse oximeter is built with a reflectance oximetry sensor, which consists of light emitting diodes and photodiode light detectors located side by side. This reflectance oximetry sensor is covered with an optical element with micro structured surface. This micro structured optical element is designed to modulate photon propagation beneath the skin tissue so that the photoplethysmogram signals of reflected lights or backscattered lights detected by the photodetector are therefore enhanced.

Comparison of oxygen saturation values and measurement times by pulse oximetry in various parts of the body.

PubMed

Yönt, Gülendam Hakverdioğlu; Korhan, Esra Akin; Khorshid, Leyla

2011-11-01

The aim of this study, which included 40 patients, was to compare the values pulse oximetry and the measurement times in various regions of the body. Data were analyzed using intraclass correlation coefficient test and paired-sample test. The confidence power value was found to be .81 for the comparison of oxygen saturation values by arterial blood gas analysis and measurement by the forehead probe. It was found that the time for oxygen saturation measurement using the forehead probe was shorter than those using the finger and toe probes. Copyright © 2011 Elsevier Inc. All rights reserved.

Detection of Anterior Circulation Large Artery Occlusion in Ischemic Stroke Using Noninvasive Cerebral Oximetry.

PubMed

Flint, Alexander C; Bhandari, Shiv G; Cullen, Sean P; Reddy, Adhikari V; Hsu, Daniel P; Rao, Vivek A; Patel, Minal; Pombra, Jasmeen; Edwards, Nancy J; Chan, Sheila L

2018-02-01

Large artery occlusion (LAO) in ischemic stroke requires recognition and triage to an endovascular stroke treatment center. Noninvasive LAO detection is needed to improve triage. Prospective study to test whether noninvasive cerebral oximetry can detect anterior circulation LAO in acute stroke. Interhemispheric ΔBrSO 2 in LAO was compared with controls. In LAO stroke, mean interhemispheric ΔBrSO 2 was -8.3±5.8% (n=19), compared with 0.4±5.8% in small artery stroke (n=17), 0.4±6.0% in hemorrhagic stroke (n=14), and 0.2±7.5% in subjects without stroke (n=19) ( P <0.001). Endovascular stroke treatment reduced the ΔBrSO 2 in most LAO subjects (16/19). Discrimination of LAO at a -3% ΔBrSO 2 cut had 84% sensitivity and 70% specificity. Addition of the G-FAST clinical score (gaze-face-arm-speech- time) to the BrSO 2 measure had 84% sensitivity and 90% specificity. Noninvasive cerebral oximetry may help detect LAO in ischemic stroke, particularly when combined with a simple clinical scoring system. © 2018 American Heart Association, Inc.

Important considerations for the newborn: access to postdischarge newborn care, pulse oximetry screening for congenital heart disease, and circumcision.

PubMed

Pattishall, Amy E; Spector, Nancy D; McPeak, Katie E

2014-12-01

This article addresses three areas in which new policies and research demonstrate the opportunity to impact the health of neonates: access to postdischarge newborn care, pulse oximetry screening for congenital heart disease, and circumcision. Recent research has identified that child healthcare providers are not typically adhering to the recommended first newborn visit within 48 h of hospital discharge. Despite its benefits, cost-effectiveness, and the recommendation that routine screening for cyanotic congenital heart disease be added to the panel of universal newborn screening, adoption of this practice is variable. Evidence suggests a significant reduction in the transmission of HIV linked to circumcision, leading professional organizations to generate new policy statements on neonatal male circumcision. Pediatric healthcare providers should pay careful attention to the timing of the first newborn outpatient follow-up visit. Pulse oximetry screening for cyanotic congenital heart disease is specific, sensitive and meets criteria for universal screening, and providers should utilize well designed screening protocols. In addition, healthcare providers for newborns, especially those who perform circumcisions, should provide nonbiased, up-to-date information on the medical, financial, and ethical aspects of the procedure.

Assessment of Pulp Oxygen Saturation Levels by Pulse Oximetry for Pulpal Diseases -A Diagnostic Study.

PubMed

Anusha, Bander; Madhusudhana, Koppolu; Chinni, Suneel Kumar; Paramesh, Yelloji

2017-09-01

Diagnosis of pulpal inflammation is a key to endodontics. Pulse oximetry is a true vitality testing device which relies on oxygen saturation levels of pulp and helps in diagnosis of different pulpal conditions. The aim of the study was to analyse oxygen saturation levels of different pulpally inflamed teeth by using pulse oximetry. Hundred patients were included in the study and categorized into five groups based on pulpal status of the test tooth by using heat test and cold test. Twenty patients were recruited in each of the experimental groups i.e., Reversible Pulpitis (RP), Irreversible Pulpitis (IP), Pulpal Necrosis (PN), Positive Control (PC, healthy teeth), and Negative Control (NC, endodontically treated teeth). Oxygen saturation levels of all the groups were measured along with each patient index finger oxygen saturation readings. Results were analysed by using ANOVA and Tukey HSD tests. The mean oxygen saturation levels of RP, IP, PN, PC and NC were 85.4%, 81.6%, 70.7%, 94.6% and 0 respectively. There was significant difference in the oxygen saturation levels between all the groups. Pulse oximeter is an effective tool in diagnosing different pulpal pathologies especially PN which was interpreted inaccurately by thermal tests.

Review of splanchnic oximetry in clinical medicine

NASA Astrophysics Data System (ADS)

Bailey, Sean M.; Mally, Pradeep V.

2016-09-01

Global tissue perfusion and oxygenation are important indicators of physiologic function in humans. The monitoring of splanchnic oximetry through the use of near-infrared spectroscopy (NIRS) is an emerging method used to assess tissue oxygenation status. Splanchnic tissue oxygenation (SrS) is thought to be potentially of high value in critically ill patients because gastrointestinal organs can often be the first to suffer ischemic injury. During conditions of hypovolemia, cardiac dysfunction, or decreased oxygen-carrying capacity, blood flow is diverted toward vital organs, such as the brain and the heart at the expense of the splanchnic circulation. While monitoring SrS has great potential benefit, there are limitations to the technology and techniques. SrS has been found to have a relatively high degree of variability that can potentially make it difficult to interpret. In addition, because splanchnic organs only lie near the skin surface in children and infants, and energy from currently available sensors only penetrates a few centimeters deep, it can be difficult to use clinically in a noninvasive manner in adults. Research thus far is showing that splanchnic oximetry holds great promise in the ability to monitor patient oxygenation status and detect disease states in humans, especially in pediatric populations.

Diagnostic accuracy of a mathematical model to predict apnea-hypopnea index using nighttime pulse oximetry

NASA Astrophysics Data System (ADS)

Ebben, Matthew R.; Krieger, Ana C.

2016-03-01

The intent of this study is to develop a predictive model to convert an oxygen desaturation index (ODI) to an apnea-hypopnea index (AHI). This model will then be compared to actual AHI to determine its precision. One thousand four hundred and sixty-seven subjects given polysomnograms with concurrent pulse oximetry between April 14, 2010, and February 7, 2012, were divided into model development (n=733) and verification groups (n=734) in order to develop a predictive model of AHI using ODI. Quadratic regression was used for model development. The coefficient of determination (r2) between the actual AHI and the predicted AHI (PredAHI) was 0.80 (r=0.90), which was significant at a p<0.001. The areas under the receiver operating characteristic curve ranged from 0.96 for AHI thresholds of ≥10 and ≥15/h to 0.97 for thresholds of ≥5 and ≥30/h. The algorithm described in this paper provides a convenient and accurate way to convert ODI to a predicted AHI. This tool makes it easier for clinicians to understand oximetry data in the context of traditional measures of sleep apnea.

Latest trends in the assessment and management of paediatric snoring and sleep apnoea.

PubMed

Sharma, S D; Kanona, H; Kumar, G; Kotecha, B

2016-05-01

To investigate the assessment and management of paediatric snoring and obstructive sleep apnoea in UK otolaryngology departments. A telephone questionnaire survey of UK otolaryngology departments was conducted over a 16-week period. The response rate was 61 per cent (85 out of 139 trusts). Use of pre-operative pulse oximetry was reported by 84 per cent of respondents, mainly to diagnose obstructive sleep apnoea (73 per cent) or stratify post-operative risk (46 per cent). Thirty-one per cent of respondents reported using post-operative pulse oximetry. Twenty-five per cent of respondents have a dedicated management protocol for paediatric obstructive sleep apnoea and snoring. Thirty-four per cent require prior clinical commissioning group approval before performing surgery. Fifty-eight per cent of respondents reported following up their obstructive sleep apnoea patients after surgery. The mean follow-up period (±standard deviation) was 6.8 ± 1.2 weeks. There is variation in the assessment and management of paediatric snoring and obstructive sleep apnoea across the UK, particularly in the use of pre- and post-operative pulse oximetry monitoring, and further guidelines regarding this are necessary.

Inaccurate pulse CO-oximetry of carboxyhemoglobin due to digital clubbing: case report.

PubMed

Harlan, Nicole; Weaver, Lindell K; Deru, Kayla

2016-01-01

Newer pulse CO-oximeters provide a non-invasive and quick means of measuring oxyhemoglobin, carboxyhemoglobin and methemoglobin. Clubbing has been reported to cause inaccuracy in pulse oximeters. We present a case of inaccurate carboxy-hemoglobin measurement by pulse CO-oximetry due to digital clubbing. An 18-year-old man with a history of cystic fibrosis presented after a suicide attempt by inhalation of exhaust. At the initial emergency department evaluation, his blood carboxyhemoglobin was 33%. He was intubated, placed on 100% oxygen and transferred to our facility. Upon arrival, we placed three different pulse CO-oximeters on different fingers and toes. Carboxyhemoglobin levels measured by these meters ranged from 9%-11%. A venous blood gas drawn on arrival showed a carboxyhemoglobin level of 2.3% after four hours on 100% oxygen by endotracheal tube. Thirty minutes later, we checked arterial blood gas, which revealed a COHb level of 0.9%. Again, non-invasive carboxyhemoglobin measurements read 10%. The patient was treated with hyperbaric oxygen for carbon monoxide poisoning. This case suggests that non-invasive measurements of carboxyhemoglobin should be correlated with the clinic history and with an arterial or venous blood gas oximetry analysis.

Non-invasive assessment of cerebral oxygenation: A comparison of retinal and transcranial oximetry

PubMed Central

Van Keer, Jan; Barbosa Breda, João; Nassiri, Vahid; De Deyne, Cathy; Genbrugge, Cornelia; Abegão Pinto, Luís; Stalmans, Ingeborg; Vandewalle, Evelien

2018-01-01

Background To investigate the correlation between cerebral (SO2-transcranial), retinal arterial (SaO2-retinal) and venous (SvO2-retinal) oxygen saturation as measured by near-infrared spectroscopy (NIRS) and retinal oximetry respectively. Methods Paired retinal and cerebral oxygen saturation measurements were performed in healthy volunteers. Arterial and venous retinal oxygen saturation and diameter were measured using a non-invasive spectrophotometric retinal oximeter. Cerebral oxygen saturation was measured using near-infrared spectroscopy. Correlations between SO2-transcranial and retinal oxygen saturation and diameter measurements were assessed using Pearson correlation coefficients. Lin’s concordance correlation coefficient (CCC) and Bland-Altman analysis were performed to evaluate the agreement between SO2-transcranial as measured by NIRS and as estimated using a fixed arterial:venous ratio as 0.3 x SaO2-retinal + 0.7 x SvO2-retinal. The individual relative weight of SaO2-retinal and SvO2-retinal to obtain the measured SO2-transcranial was calculated for all subjects. Results Twenty-one healthy individuals aged 26.4 ± 2.2 years were analyzed. SO2-transcranial was positively correlated with both SaO2-retinal and SvO2-retinal (r = 0.44, p = 0.045 and r = 0.43, p = 0.049 respectively) and negatively correlated with retinal venous diameter (r = -0.51, p = 0.017). Estimated SO2-transcranial based on retinal oximetry showed a tolerance interval of (-13.70 to 14.72) and CCC of 0.46 (95% confidence interval: 0.05 to 0.73) with measured SO2-transcranial. The average relative weights of SaO2-retinal and SvO2-retinal to obtain SO2-transcranial were 0.31 ± 0.11 and 0.69 ± 0.11, respectively. Conclusion This is the first study to show the correlation between retinal and cerebral oxygen saturation, measured by NIRS and retinal oximetry. The average relative weight of arterial and venous retinal oxygen saturation to obtain the measured transcranial oxygen saturation as measured by NIRS, approximates the established arterial:venous ratio of 30:70 closely, but shows substantial inter-individual variation. These findings provide a proof of concept for the role of retinal oximetry in evaluating cerebral oxygenation. PMID:29304150

Automated Screening of Children With Obstructive Sleep Apnea Using Nocturnal Oximetry: An Alternative to Respiratory Polygraphy in Unattended Settings

PubMed Central

Álvarez, Daniel; Alonso-Álvarez, María L.; Gutiérrez-Tobal, Gonzalo C.; Crespo, Andrea; Kheirandish-Gozal, Leila; Hornero, Roberto; Gozal, David; Terán-Santos, Joaquín; Del Campo, Félix

2017-01-01

Study Objectives: Nocturnal oximetry has become known as a simple, readily available, and potentially useful diagnostic tool of childhood obstructive sleep apnea (OSA). However, at-home respiratory polygraphy (HRP) remains the preferred alternative to polysomnography (PSG) in unattended settings. The aim of this study was twofold: (1) to design and assess a novel methodology for pediatric OSA screening based on automated analysis of at-home oxyhemoglobin saturation (SpO2), and (2) to compare its diagnostic performance with HRP. Methods: SpO2 recordings were parameterized by means of time, frequency, and conventional oximetric measures. Logistic regression models were optimized using genetic algorithms (GAs) for three cutoffs for OSA: 1, 3, and 5 events/h. The diagnostic performance of logistic regression models, manual obstructive apnea-hypopnea index (OAHI) from HRP, and the conventional oxygen desaturation index ≥ 3% (ODI3) were assessed. Results: For a cutoff of 1 event/h, the optimal logistic regression model significantly outperformed both conventional HRP-derived ODI3 and OAHI: 85.5% accuracy (HRP 74.6%; ODI3 65.9%) and 0.97 area under the receiver operating characteristics curve (AUC) (HRP 0.78; ODI3 0.75) were reached. For a cutoff of 3 events/h, the logistic regression model achieved 83.4% accuracy (HRP 85.0%; ODI3 74.5%) and 0.96 AUC (HRP 0.93; ODI3 0.85) whereas using a cutoff of 5 events/h, oximetry reached 82.8% accuracy (HRP 85.1%; ODI3 76.7) and 0.97 AUC (HRP 0.95; ODI3 0.84). Conclusions: Automated analysis of at-home SpO2 recordings provide accurate detection of children with high pretest probability of OSA. Thus, unsupervised nocturnal oximetry may enable a simple and effective alternative to HRP and PSG in unattended settings. Citation: Álvarez D, Alonso-Álvarez ML, Gutiérrez-Tobal GC, Crespo A, Kheirandish-Gozal L, Hornero R, Gozal D, Terán-Santos J, Del Campo F. Automated screening of children with obstructive sleep apnea using nocturnal oximetry: an alternative to respiratory polygraphy in unattended settings. J Clin Sleep Med. 2017;13(5):693–702. PMID:28356177

How to use saturation monitoring in newborns.

PubMed

McVea, Steven; McGowan, Michael; Rao, Bharathi

2018-05-10

Pulse oximetry is a first-line monitoring tool, used in neonatal medicine routinely as a part of continuous monitoring during intensive care. It is also used to guide response to resuscitation and as a screening tool for congenital heart disease. Despite its widespread use, many healthcare providers are unaware of the underlying principles and limitations of pulse oximetry in neonates. In this article, we will discuss the physiological and technological principles behind the use of saturation monitoring and its use in neonatal practice. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

The Feasibility and Validity of a Remote Pulse Oximetry System for Pulmonary Rehabilitation: A Pilot Study

PubMed Central

Tang, Jonathan; Mandrusiak, Allison; Russell, Trevor

2012-01-01

Pulmonary rehabilitation is an effective treatment for people with chronic obstructive pulmonary disease. However, access to these services is limited especially in rural and remote areas. Telerehabilitation has the potential to deliver pulmonary rehabilitation programs to these communities. The aim of this study was threefold: to establish the technical feasibility of transmitting real-time pulse oximetry data, determine the validity of remote measurements compared to conventional face-to-face measures, and evaluate the participants' perception of the usability of the technology. Thirty-seven healthy individuals participated in a single remote pulmonary rehabilitation exercise session, conducted using the eHAB telerehabilitation system. Validity was assessed by comparing the participant's oxygen saturation and heart rate with the data set received at the therapist's remote location. There was an 80% exact agreement between participant and therapist data sets. The mean absolute difference and Bland and Altman's limits of agreement fell within the minimum clinically important difference for both oxygen saturation and heart rate values. Participants found the system easy to use and felt confident that they would be able to use it at home. Remote measurement of pulse oximetry data for a pulmonary rehabilitation exercise session was feasible and valid when compared to conventional face-to-face methods. PMID:23049549

AutoCPAP initiation at home: optimal trial duration and cost-effectiveness.

PubMed

Bachour, Adel; Virkkala, Jussi T; Maasilta, Paula K

2007-11-01

The duration of automatic computer-controlled continuous positive airway pressure device (autoCPAP) initiation at home varies largely between sleep centers. Our objectives were to evaluate the cost-effectiveness and to find the optimal trial duration. Of the 206 consecutive CPAP-naive patients with obstructive sleep apnea syndrome, who were referred to our hospital, 166 received autoCPAP for a 5-day trial at home. Of the 166 patients, 89 (15 women) showed a successful 5-day autoCPAP trial (normalized oximetry and mask-on time exceeding 4 h/day for at least 4 days). For the first trial day, 88 (53%) patients had normalized oximetry and a mask-on time exceeding 4 h. A 1-day autoCPAP trial EUR 668 was less cost-effective than a 5-day trial EUR 653, with no differences in values of efficient CPAP pressure or residual apnea-hypopnea index (AHI). The systematic requirement of oximetry monitoring raised the cost considerably from EUR 481 to EUR 668. In selected patients with obstructive sleep apnea, the optimal duration for initiating CPAP therapy at home by autoCPAP is 5 days. Although a 1-day trial was sufficient to determine the CPAP pressure requirement, it was not cost-effective and had a high rate of failure.

Prediction of pulmonary hypertension in idiopathic pulmonary fibrosis☆

PubMed Central

Zisman, David A.; Ross, David J.; Belperio, John A.; Saggar, Rajan; Lynch, Joseph P.; Ardehali, Abbas; Karlamangla, Arun S.

2007-01-01

Summary Background Reliable, noninvasive approaches to the diagnosis of pulmonary hypertension in idiopathic pulmonary fibrosis are needed. We tested the hypothesis that the forced vital capacity to diffusing capacity ratio and room air resting pulse oximetry may be combined to predict mean pulmonary artery pressure (MPAP) in idiopathic pulmonary fibrosis. Methods Sixty-one idiopathic pulmonary fibrosis patients with available right-heart catheterization were studied. We regressed measured MPAP as a continuous variable on pulse oximetry (SpO2) and percent predicted forced vital capacity (FVC) to percent-predicted diffusing capacity ratio (% FVC/% DLco) in a multivariable linear regression model. Results Linear regression generated the following equation: MPAP = −11.9+0.272 × SpO2+0.0659 × (100−SpO2)2+3.06 × (% FVC/% DLco); adjusted R2 = 0.55, p<0.0001. The sensitivity, specificity, positive predictive and negative predictive value of model-predicted pulmonary hypertension were 71% (95% confidence interval (CI): 50–89%), 81% (95% CI: 68–92%), 71% (95% CI: 51–87%) and 81% (95% CI: 68–94%). Conclusions A pulmonary hypertension predictor based on room air resting pulse oximetry and FVC to diffusing capacity ratio has a relatively high negative predictive value. However, this model will require external validation before it can be used in clinical practice. PMID:17604151

Comparison of the efficacy of a custom-made pulse oximeter probe with digital electric pulp tester, cold spray, and rubber cup for assessing pulp vitality.

PubMed

Dastmalchi, Nafiseh; Jafarzadeh, Hamid; Moradi, Saeed

2012-09-01

The ideal technique for the evaluation of pulp vitality should be noninvasive, painless, objective, reliable, and reproducible. To achieve this, the most routine tests are sensitivity tests. However, a major shortcoming with these tests is that they indirectly indicate pulp vitality by measuring a neural response. Pulse oximetry is a well-established oxygen saturation monitoring technique broadly used in medicine. However, its efficacy as the pulp vitality test should be evaluated. The aim of this study was to design and build a custom-made pulse oximeter dental probe and to evaluate its efficacy in comparison with electric pulp tester, cold spray, and a rubber cup in pulp vitality testing. Twenty-four single-canal mandibular premolars needing endodontic treatment were selected. The patients did not have systemic disease and did not consume drugs. Also, they had no clinically relevant signs of necrosis. The selected teeth were pulpally tested with 4 kinds of tests including pulse oximetry, the electric test, cold spray, and the rubber cup. After endodontic treatment of these teeth, which revealed the actual status of the pulp, the results were analyzed by the kappa test to show the efficacy of these tests. When comparing electric, cold, heat, and pulse oximeter tests with the gold standard, the kappa agreement coefficient was 18%, 18%, 14%, and 91%, respectively. The sensitivity of pulse oximetry, a rubber cup, electric test, and cold spray was 0.93, 0.60, 0.60, and 0.53, respectively. The specificity of these tests was 1.00, 0.55, 0.22, and 0.66, respectively. Pulp testing by using pulse oximetry is more reliable than the electric test, rubber cup, and cold spray. The custom-made pulse oximeter dental probe is an effective and objective method for pulp vitality assessment. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Beneficial effect of nocturnal oximetric control on the clinical and gasometric situation and the prognosis of patients with home non-invasive mechanical ventilation.

PubMed

Hidalgo Carvajal, Raúl; Sánchez Casado, Marcelino; de Miguel-Díez, Javier; López Gabaldón, Encarnación

2018-02-28

The effectiveness of home non-invasive mechanical ventilation (NIMV) is assessed by determining blood gas values in wakefulness, the evolution of their symptoms, and the monitoring of ventilation at night. The aim of our study is to evaluate whether defined values reached with outpatient monitoring by oximetry is related to the clinical, arterial gases and survival of a sample of patients with home NIMV. Retrospective observational cohort study of a series of patients receiving home NIMV treatment for different causes. Patients with amyotrophic lateral sclerosis and less than 3 months of follow-up were excluded. The evolution of the patient's symptoms, their baseline arterial blood gases in wakefulness, and home nocturnal oximetry records, are evaluated at each outpatient visit. Good maintained oximetry control (MOC) was defined when mean O2 saturation values were reached and maintained until the last revision. Patient groups were considered, according to whether or not a good MOC was achieved during follow-up. Four hundred patients were evaluated. Three hundred and sixty four (91%) were included in the study; their median age was 68 years, 51% were male. 37.6% had a good MOC during follow-up. Compared to patients with not good MOC, a better long-term mortality was obtained (16.8% vs 28.2%, P=.013), and an improvement in symptoms (33.8% vs 18.6%, P=.002) and a lower proportion of patients with persistently>50mmHg PaCO2 (14.2% vs. 33.9%, P<.001) was observed. In the follow-up of patients with home NIMV in our context, values defined in home nocturnal oximetry (good MOC) are positively associated with clinical, gasometric and longer-term survival. Copyright © 2018 Elsevier España, S.L.U. All rights reserved.

A feasibility study of cerebral oximetry during in-hospital mechanical and manual cardiopulmonary resuscitation*.

PubMed

Parnia, Sam; Nasir, Asad; Ahn, Anna; Malik, Hanan; Yang, Jie; Zhu, Jiawen; Dorazi, Francis; Richman, Paul

2014-04-01

A major hurdle limiting the ability to improve the quality of resuscitation has been the lack of a noninvasive real-time detection system capable of monitoring the quality of cerebral and other organ perfusion, as well as oxygen delivery during cardiopulmonary resuscitation. Here, we report on a novel system of cerebral perfusion targeted resuscitation. An observational study evaluating the role of cerebral oximetry (Equanox; Nonin, Plymouth, MI, and Invos; Covidien, Mansfield, MA) as a real-time marker of cerebral perfusion and oxygen delivery together with the impact of an automated mechanical chest compression system (Life Stat; Michigan Instruments, Grand Rapids, MI) on oxygen delivery and return of spontaneous circulation following in-hospital cardiac arrest. Tertiary medical center. In-hospital cardiac arrest patients (n = 34). Cerebral oximetry provided real-time information regarding the quality of perfusion and oxygen delivery. The use of automated mechanical chest compression device (n = 12) was associated with higher regional cerebral oxygen saturation compared with manual chest compression device (n = 22) (53.1% ± 23.4% vs 24% ± 25%, p = 0.002). There was a significant difference in mean regional cerebral oxygen saturation (median % ± interquartile range) in patients who achieved return of spontaneous circulation (n = 15) compared with those without return of spontaneous circulation (n = 19) (47.4% ± 21.4% vs 23% ± 18.42%, p < 0.001). After controlling for patients achieving return of spontaneous circulation or not, significantly higher mean regional cerebral oxygen saturation levels during cardiopulmonary resuscitation were observed in patients who were resuscitated using automated mechanical chest compression device (p < 0.001). The integration of cerebral oximetry into cardiac arrest resuscitation provides a novel noninvasive method to determine the quality of cerebral perfusion and oxygen delivery to the brain. The use of automated mechanical chest compression device during in-hospital cardiac arrest may lead to improved oxygen delivery and organ perfusion.

Multisite EPR oximetry from multiple quadrature harmonics.

PubMed

Ahmad, R; Som, S; Johnson, D H; Zweier, J L; Kuppusamy, P; Potter, L C

2012-01-01

Multisite continuous wave (CW) electron paramagnetic resonance (EPR) oximetry using multiple quadrature field modulation harmonics is presented. First, a recently developed digital receiver is used to extract multiple harmonics of field modulated projection data. Second, a forward model is presented that relates the projection data to unknown parameters, including linewidth at each site. Third, a maximum likelihood estimator of unknown parameters is reported using an iterative algorithm capable of jointly processing multiple quadrature harmonics. The data modeling and processing are applicable for parametric lineshapes under nonsaturating conditions. Joint processing of multiple harmonics leads to 2-3-fold acceleration of EPR data acquisition. For demonstration in two spatial dimensions, both simulations and phantom studies on an L-band system are reported. Copyright © 2011 Elsevier Inc. All rights reserved.

VCSEL based, wearable, continuously monitoring pulse oximeter.

PubMed

Kollmann, Daniel; Hogan, William K; Steidl, Charles; Hibbs-Brenner, Mary K; Hedin, Daniel S; Lichter, Patrick A

2013-01-01

We present the development of a novel pulse oximeter based on low power, low cost, Vertical Cavity Surface Emitting Laser (VCSEL) technology. This new design will help address a need to perform regular measurements of pulse oximetry for patients with chronic obstructive pulmonary disease. VCSELs with wavelengths suitable for pulse oximetry were developed and packaged in a PLCC package for a low cost solution that is easy to integrate into a pulse oximeter design. The VCSELs were integrated into a prototype pulse oximeter that is unobtrusive and suitable for long term wearable use. The prototype achieved good performance compared the Nonin Onyx II pulse oximeter at less than one fifth the weight in a design that can be worn behind the ear like a hearing aid.

Research: Comparison of the Accuracy of a Pocket versus Standard Pulse Oximeter.

PubMed

da Costa, João Cordeiro; Faustino, Paula; Lima, Ricardo; Ladeira, Inês; Guimarães, Miguel

2016-01-01

Pulse oximetry has become an essential tool in clinical practice. With patient self-management becoming more prevalent, pulse oximetry self-monitoring has the potential to become common practice in the near future. This study sought to compare the accuracy of two pulse oximeters, a high-quality standard pulse oximeter and an inexpensive pocket pulse oximeter, and to compare both devices with arterial blood co-oximetry oxygen saturation. A total of 95 patients (35.8% women; mean [±SD] age 63.1 ± 13.9 years; mean arterial pressure was 92 ± 12.0 mmHg; mean axillar temperature 36.3 ± 0.4°C) presenting to our hospital for blood gas analysis was evaluated. The Bland-Altman technique was performed to calculate bias and precision, as well as agreement limits. Student's t test was performed. Standard oximeter presented 1.84% bias and a precision error of 1.80%. Pocket oximeter presented a bias of 1.85% and a precision error of 2.21%. Agreement limits were -1.69% to 5.37% (standard oximeter) and -2.48% to 6.18% (pocket oximeter). Both oximeters presented bias, which was expected given previous research. The pocket oximeter was less precise but had agreement limits that were comparable with current evidence. Pocket oximeters can be powerful allies in clinical monitoring of patients based on a self-monitoring/efficacy strategy.

Theoretical model for optical oximetry at the capillary level: exploring hemoglobin oxygen saturation through backscattering of single red blood cells

NASA Astrophysics Data System (ADS)

Liu, Rongrong; Spicer, Graham; Chen, Siyu; Zhang, Hao F.; Yi, Ji; Backman, Vadim

2017-02-01

Oxygen saturation (sO2) of red blood cells (RBCs) in capillaries can indirectly assess local tissue oxygenation and metabolic function. For example, the altered retinal oxygenation in diabetic retinopathy and local hypoxia during tumor development in cancer are reflected by abnormal sO2 of local capillary networks. However, it is far from clear whether accurate label-free optical oximetry (i.e., measuring hemoglobin sO2) is feasible from dispersed RBCs at the single capillary level. The sO2-dependent hemoglobin absorption contrast present in optical scattering signal is complicated by geometry-dependent scattering from RBCs. We present a numerical study of backscattering spectra from single RBCs based on the first-order Born approximation, considering practical factors: RBC orientations, size variation, and deformations. We show that the oscillatory spectral behavior of RBC geometries is smoothed by variations in cell size and orientation, resulting in clear sO2-dependent spectral contrast. In addition, this spectral contrast persists with different mean cellular hemoglobin content and different deformations of RBCs. This study shows for the first time the feasibility of, and provides a theoretical model for, label-free optical oximetry at the single capillary level using backscattering-based imaging modalities, challenging the popular view that such measurements are impossible at the single capillary level.

Critical congenital heart disease screening practices among licensed midwives in washington state.

PubMed

Evers, Patrick D; Vernon, Margaret M; Schultz, Amy H

2015-01-01

Since 2011, pulse oximetry screening for critical congenital heart disease (CCHD) has been recommended for newborns. Initial implementation guidelines focused on in-hospital births. Recent publications affirm the importance of universal screening, including for out-of-hospital births. No published data describe CCHD screening rates for out-of-hospital births. Licensed midwives in Washington state were surveyed regarding their current CCHD screening practices, volume of births attended annually, and typical newborn follow-up practices. For those who indicated they were screening, additional information was obtained about equipment used, timing of screening, and rationale for voluntarily initiating screening. For those who indicated that they were not screening, information regarding barriers to implementation was solicited. Of the 61 midwives in our sample, 98% indicated they were aware of published guidelines recommending universal newborn screening for CCHD utilizing pulse oximetry. Furthermore, 52% indicated that they were screening for CCHD currently. Ten percent stated they do not intend to screen, whereas the remaining respondents indicated that they plan to screen in the future. The primary barriers to screening were the cost of pulse oximetry equipment and inadequate training in screening technique and interpretation. Although voluntary implementation of CCHD screening by licensed midwives in Washington is increasing, it lags behind the implementation rates reported for in-hospital births. © 2015 by the American College of Nurse-Midwives.

ACCURACY OF NONINVASIVE ANESTHETIC MONITORING IN THE ANESTHETIZED GIRAFFE (GIRAFFA CAMELOPARDALIS).

PubMed

Bertelsen, Mads F; Grøndahl, Carsten; Stegmann, George F; Sauer, Cathrine; Secher, Niels H; Hasenkam, J Michael; Damkjær, Mads; Aalkjær, Christian; Wang, Tobias

2017-09-01

This study evaluated the accuracy of pulse oximetry, capnography, and oscillometric blood pressure during general anesthesia in giraffes (Giraffa camelopardalis). Thirty-two giraffes anesthetized for physiologic experiments were instrumented with a pulse oximeter transmittance probe positioned on the tongue and a capnograph sampling line placed at the oral end of the endotracheal tube. A human size 10 blood pressure cuff was placed around the base of the tail, and an indwelling arterial catheter in the auricular artery continuously measured blood pressure. Giraffes were intermittently ventilated using a Hudson demand valve throughout the procedures. Arterial blood for blood gas analysis was collected at multiple time points. Relationships between oxygen saturation as determined by pulse oximetry and arterial oxygen saturation, between arterial carbon dioxide partial pressure and end-tidal carbon dioxide, and between oscillometric pressure and invasive arterial blood pressure were assessed, and the accuracy of pulse oximetry, capnography, and oscillometric blood pressure monitoring evaluated using Bland-Altman analysis. All three noninvasive methods provided relatively poor estimates of the reference values. Receiver operating characteristic curve fitting was used to determine cut-off values for hypoxia, hypocapnia, hypercapnia, and hypotension for dichotomous decision-making. Applying these cut-off values, there was reasonable sensitivity for detection of hypocapnia, hypercapnia, and hypotension, but not for hypoxemia. Noninvasive anesthetic monitoring should be interpreted with caution in giraffes and, ideally, invasive monitoring should be employed.

The efficacy of noninvasive hemoglobin measurement by pulse CO-oximetry in neonates.

PubMed

Jung, Young Hwa; Lee, Juyoung; Kim, Han-Suk; Shin, Seung Han; Sohn, Jin A; Kim, Ee-Kyung; Choi, Jung-Hwan

2013-01-01

To evaluate clinical applicability of noninvasive hemoglobin (Hb) measurement with a pulse CO-oximeter in neonates. Prospective comparison study. Neonatal ICU. Fifty-six preterm and term infants with median age = 20 days (range = 1-98 days) and median weight = 1,440 g (range = 530-4,230 g). Hb measurements by Pulse CO-Oximetry (Masimo Radical-7) were recorded immediately prior to venous samplings. The collected data were compared with the corresponding venous Hb level obtained in laboratory testing, and a total of 137 data pairs were analyzed. Noninvasive Hb values measured with a pulse CO-oximeter were significantly correlated with the venous Hb levels (correlation coefficient, r = 0.758; p < 0.001). Hb values measured with a pulse CO-oximeter were higher than those measured with a laboratory hematology analyzer (13.3 ± 2.6g/dL vs. 12.5 ± 3.1g/dL). In terms of the agreement between the laboratory analyzer and the pulse CO-oximeter, 94.8% of the measurements fell within two standard deviations of the mean difference. Noninvasive Hb measurements with Pulse CO-Oximetry provide clinically acceptable accuracy, and they were significantly correlated with laboratory Hb measurement in neonates. In terms of the clinical applicability, noninvasive Hb monitoring with a pulse CO-oximeter could be useful in the early detection of Hb changes in neonates.

Pulmonary embolus

MedlinePlus

... how well your lungs are working: Arterial blood gases Pulse oximetry The following imaging tests can help ... 2018, A.D.A.M., Inc. Duplication for commercial use must be authorized in writing by ADAM ...

Earpiece with sensors to measure/monitor multiple physiological variables

NASA Technical Reports Server (NTRS)

Cooper, Tommy G. (Inventor); Schulze, Arthur E. (Inventor)

2003-01-01

An apparatus and method for positioning sensors relative to one another and anatomic features in a non-invasive device for measuring and monitoring multiple physiological variables from a single site uses an earpiece incorporating a shielded pulse oximetry sensor (POS) having a miniaturized set of LEDs and photosensors configured for pulse oximetry measurements in the reflectance mode and located in the earpiece so as to position the POS against a rear wall of an ear canal. The earpiece also includes a thermopile of no larger than 7 mm. in diameter located on the earpiece to so as to position the thermopile past a second turn of an external auditory meatus so as to view the tympanic membrane. The thermopile includes a reference temperature sensor attached to its base for ambient temperature compensation.

Comparison of tissue oximeters on a liquid phantom with adjustable optical properties

PubMed Central

Kleiser, S.; Nasseri, N.; Andresen, B.; Greisen, G.; Wolf, M.

2016-01-01

The SafeBoosC trial showed that cerebral oximetry combined with a treatment guideline can reduce the the burden of hypoxia in neonates by 50% [Brit. Med. J. 350, g7635 (2015)25569128]. However, guidelines based on oximetry by one oximeter are not directly usable by other oximeters. We made a blood-lipid phantom simulating the neonatal head to determine the relation between oxygenation values obtained by different oximeters. We calculated coefficients for easy conversion from one oximeter to the other. We additionally determined the corresponding SafeBoosC intervention thresholds at which we measured an uncertainty of up to 9.2% when varying hemoglobin content from 25μM to 70μM. In conclusion, this paper makes the comparison of absolute values obtained by different oximeters possible. PMID:27570691

Use of biomedical photonics in gynecological surgery: a uterine transplantation model

PubMed Central

Saso, Srdjan; Clancy, Neil T; Jones, Benjamin P; Bracewell-Milnes, Timothy; Al-Memar, Maya; Cannon, Eleanor M; Ahluwalia, Simran; Yazbek, Joseph; Thum, Meen-Yau; Bourne, Tom; Elson, Daniel S; Smith, James Richard; Ghaem-Maghami, Sadaf

2018-01-01

Aim: Uterine transplantation (UTx) has been proposed as a treatment for permanent absolute uterine factor infertility. The study aims were to compare pulse oximetry and multispectral imaging (MSI), for intraoperative tracking of uterine oxygen saturation in animal UTx models (rabbit and sheep). Results/methodology: Imaging results confirmed the re-establishment of adequate perfusion in the transplanted organ after surgery. Comparison of oxygen saturation values between the pre-UTx donor and post-UTx recipient, and pre-UTx and post-UTx recipient reveals a statistically significant decrease in saturation levels post-UTx. Conclusion: The use of MSI is the first case in gynecology and has demonstrated promise of possible future human use. MSI technique has advantages over pulse oximetry – it provides spatial information in a real-time, noncontact manner. PMID:29682321

Arterial blood oxygen saturation during blood pressure cuff-induced hypoperfusion

NASA Astrophysics Data System (ADS)

Kyriacou, P. A.; Shafqat, K.; Pal, S. K.

2007-10-01

Pulse oximetry has been one of the most significant technological advances in clinical monitoring in the last two decades. Pulse oximetry is a non-invasive photometric technique that provides information about the arterial blood oxygen saturation (SpO2) and heart rate, and has widespread clinical applications. When peripheral perfusion is poor, as in states of hypovolaemia, hypothermia and vasoconstriction, oxygenation readings become unreliable or cease. The problem arises because conventional pulse oximetry sensors must be attached to the most peripheral parts of the body, such as finger, ear or toe, where pulsatile flow is most easily compromised. Pulse oximeters estimate arterial oxygen saturation by shining light at two different wavelengths, red and infrared, through vascular tissue. In this method the ac pulsatile photoplethysmographic (PPG) signal associated with cardiac contraction is assumed to be attributable solely to the arterial blood component. The amplitudes of the red and infrared ac PPG signals are sensitive to changes in arterial oxygen saturation because of differences in the light absorption of oxygenated and deoxygenated haemoglobin at these two wavelengths. From the ratios of these amplitudes, and the corresponding dc photoplethysmographic components, arterial blood oxygen saturation (SpO2) is estimated. Hence, the technique of pulse oximetry relies on the presence of adequate peripheral arterial pulsations, which are detected as photoplethysmographic (PPG) signals. The aim of this study was to investigate the effect of pressure cuff-induced hypoperfusion on photoplethysmographic signals and arterial blood oxygen saturation using a custom made finger blood oxygen saturation PPG/SpO2 sensor and a commercial finger pulse oximeter. Blood oxygen saturation values from the custom oxygen saturation sensor and a commercial finger oxygen saturation sensor were recorded from 14 healthy volunteers at various induced brachial pressures. Both pulse oximeters showed gradual decrease of saturations during induced hypoperfusion which demonstrate the direct relation between blood volumes (PPG amplitudes), arterial vessel stenosis and blood oxygen saturation. The custom made pulse oximeter was found to be more sensitive to SpO2 changes than the commercial pulse oximeter especially at high occluding pressures.

Pulse Oximetry

MedlinePlus

... carrying. By using a small device called a pulse oximeter , your blood oxygen level can be checked without ... and “Oxygen Therapy for Children”) How does a pulse oximeter work? A pulse oximeter comes either as a ...

[transcutaneous oximetry--between theory and practice].

PubMed

Zulec, Mirna

2014-10-01

Transcutaneous oximetry is a procedure used to measure the pressure of oxygen in tissue and to determine oxygenation level. It is essential to determine the state of microcirculation and is used to assess the necessity and level of amputation and the effect of revascularization procedures, as a predictor of wound healing and hyperbaric oxygen therapy (HBOT) effectiveness tool. The measurement is done by the application electrode measuring point and the result is measured in mm Hg. Tissue with adequate oxygen level has a value greater than 50 mm Hg. Values between 20 and 40 mm Hg are considered hypoxic, while those below 20 mm Hg indicate extreme hypoxia. In Croatia, TcPO2 is commonly used for HBOT assessment but there is the need of broader application to objectify and facilitate procedures in the care of persons with impaired microcirculation.

Handheld four-wavelength retinal vessel oximeter

NASA Astrophysics Data System (ADS)

Heaton, Larry C.; Smith, Matthew H.; Denninghoff, Kurt R.; Hillman, Lloyd W.

2000-06-01

Several techniques for measuring the oxygen saturation of blood in retinal vessels have been reported. One interesting application of retinal vessel oximetry is the identification of occult blood loss in trauma victims. However, all the devices described to date are too bulky and cumbersome to be used in a trauma bay or in the field. We present a design for a handheld instrument that performs four-wavelength retinal vessel oximetry. This device is comparable in size and weight to a commercially available camcorder, and is suitable for use in the trauma bay. The compact size of this device could also extend its applications beyond traditional clinical settings, as it could be used by primary care physicians and home health care workers for the screening and monitoring of ophthalmic diseases. Principles of operation and preliminary data from the device will be described.

EPR oximetry in three spatial dimensions using sparse spin distribution

NASA Astrophysics Data System (ADS)

Som, Subhojit; Potter, Lee C.; Ahmad, Rizwan; Vikram, Deepti S.; Kuppusamy, Periannan

2008-08-01

A method is presented to use continuous wave electron paramagnetic resonance imaging for rapid measurement of oxygen partial pressure in three spatial dimensions. A particulate paramagnetic probe is employed to create a sparse distribution of spins in a volume of interest. Information encoding location and spectral linewidth is collected by varying the spatial orientation and strength of an applied magnetic gradient field. Data processing exploits the spatial sparseness of spins to detect voxels with nonzero spin and to estimate the spectral linewidth for those voxels. The parsimonious representation of spin locations and linewidths permits an order of magnitude reduction in data acquisition time, compared to four-dimensional tomographic reconstruction using traditional spectral-spatial imaging. The proposed oximetry method is experimentally demonstrated for a lithium octa- n-butoxy naphthalocyanine (LiNc-BuO) probe using an L-band EPR spectrometer.

Physiological Factors Analysis in Unpressurized Aircraft Cabins

NASA Astrophysics Data System (ADS)

Patrao, Luis; Zorro, Sara; Silva, Jorge

2016-11-01

Amateur and sports flight is an activity with growing numbers worldwide. However, the main cause of flight incidents and accidents is increasingly pilot error, for a number of reasons. Fatigue, sleep issues and hypoxia, among many others, are some that can be avoided, or, at least, mitigated. This article describes the analysis of psychological and physiological parameters during flight in unpressurized aircraft cabins. It relates cerebral oximetry and heart rate with altitude, as well as with flight phase. The study of those parameters might give clues on which variations represent a warning sign to the pilot, thus preventing incidents and accidents due to human factors. Results show that both cerebral oximetry and heart rate change along the flight and altitude in the alert pilot. The impaired pilot might not reveal these variations and, if this is detected, he can be warned in time.

Quantifying the effect of adipose tissue in muscle oximetry by near infrared spectroscopy

PubMed Central

Nasseri, Nassim; Kleiser, Stefan; Ostojic, Daniel; Karen, Tanja; Wolf, Martin

2016-01-01

Change of muscle tissue oxygen saturation (StO2), due to exercise, measured by near infrared spectroscopy (NIRS) is known to be lower for subjects with higher adipose tissue thickness. This is most likely not physiological but caused by the superficial fat and adipose tissue. In this paper we assessed, in vitro, the influence of adipose tissue thickness on muscle StO2, measured by NIRS oximeters. We measured StO2 of a liquid phantom by 3 continuous wave (CW) oximeters (Sensmart Model X-100 Universal Oximetry System, INVOS 5100C, and OxyPrem v1.3), as well as a frequency-domain oximeter, OxiplexTS, through superficial layers with 4 different thicknesses. Later, we employed the results to calibrate OxyPrem v1.3 for adipose tissue thickness in-vivo. PMID:27895999

New spectral imaging techniques for blood oximetry in the retina

NASA Astrophysics Data System (ADS)

Alabboud, Ied; Muyo, Gonzalo; Gorman, Alistair; Mordant, David; McNaught, Andrew; Petres, Clement; Petillot, Yvan R.; Harvey, Andrew R.

2007-07-01

Hyperspectral imaging of the retina presents a unique opportunity for direct and quantitative mapping of retinal biochemistry - particularly of the vasculature where blood oximetry is enabled by the strong variation of absorption spectra with oxygenation. This is particularly pertinent both to research and to clinical investigation and diagnosis of retinal diseases such as diabetes, glaucoma and age-related macular degeneration. The optimal exploitation of hyperspectral imaging however, presents a set of challenging problems, including; the poorly characterised and controlled optical environment of structures within the retina to be imaged; the erratic motion of the eye ball; and the compounding effects of the optical sensitivity of the retina and the low numerical aperture of the eye. We have developed two spectral imaging techniques to address these issues. We describe first a system in which a liquid crystal tuneable filter is integrated into the illumination system of a conventional fundus camera to enable time-sequential, random access recording of narrow-band spectral images. Image processing techniques are described to eradicate the artefacts that may be introduced by time-sequential imaging. In addition we describe a unique snapshot spectral imaging technique dubbed IRIS that employs polarising interferometry and Wollaston prism beam splitters to simultaneously replicate and spectrally filter images of the retina into multiple spectral bands onto a single detector array. Results of early clinical trials acquired with these two techniques together with a physical model which enables oximetry map are reported.

Obesity-hypoventilation syndrome and associated factors.

PubMed

Espínola Rodríguez, Ana; Lores Obradors, Luis; Parellada Esquius, Neus; Rubio Muñoz, Felisa; Espinosa Gonzalez, Neus; Arellano Marcuello, Elisabet

2018-02-23

Obesity causes important alterations in the respiratory physiology like sleep obstructive apnoea (SOA) and obesity-hypoventilation syndrome (OHS), both associated with high morbidity and mortality. Also, these entities are clearly infradiagnosed and in the case of OHS the prevalence is unknown in the general obese population. To determine the prevalence of OHS in the population of patients with morbid obesity and to know the comorbidity related with OHS, the associated respiratory symptoms and the pulse oximetry alterations. Descriptive study. Selection of 136 adult patients with morbid obesity (BMI >40). Collected were, anthropometric data, toxic habits, concomitant disease, symptom data, analytic data, dyspnoea grade, sleepiness scale (Epworth Test), electrocardiogram, chest X-ray, spirometry, nocturne ambulatory pulse oximetry and arterial gasometry. 136 were studied, mean age 60 years old (SD 12.9 years), 73% (98) were women; 6.6% of patients presented diurnal hypercapnia indicative of OHS; 72% presented high blood pressure, 44% dyslipidaemia, 18% presented cardiovascular disease, 83% snored and 46% had apnoea; 30% presented stageII dyspnoea and 10% stageIII. The desaturation/hour index was above 3% ≥30 of occasions in 28.6% of patients and the percentage of patients with saturations <90% more than 30% of the time was 23.5%. The results were worse in patients with OHS. The prevalence of OHS was lower than expected. Noteworthy was the high comorbidity of cardiovascular disease and the high frequency of respiratory symptoms associated with important alterations of pulse oximetry. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Muscle Oximetry in Sports Science: A Systematic Review.

PubMed

Perrey, Stephane; Ferrari, Marco

2018-03-01

Since the introduction (in 2006) of commercially available portable wireless muscle oximeters, the use of muscle near-infrared spectroscopy (NIRS) technology is gaining in popularity as an application to observe changes in muscle metabolism and muscle oxygenation during and after exercise or training interventions in both laboratory and applied sports settings. The objectives of this systematic review were to highlight the application of muscle oximetry in evaluating oxidative skeletal muscle performance to sport activities and emphasize how this technology has been applied to exercise and training. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in a systematic fashion to search, assess and synthesize existing literature on this topic. The Scopus and MEDLINE/PubMed electronic databases were searched to 1 March 2017. Potential inclusions were screened against eligibility criteria relating to recreationally trained to elite athletes, with or without training programs, who must have assessed physiological variables monitored by commercial oximeters or NIRS instrumentation. Of the 14,609 identified records, only 57 studies met the eligibility criteria. This systematic review highlighted a number of key findings in 16 sporting activities. Overall, NIRS information can be used as a marker of skeletal muscle oxidative capacity and for analyzing muscle performance factors. Although NIRS instrumentation is promising in evaluating oxidative skeletal muscle performance when used in sport settings, there is still the need for further instrumental development and randomized/longitudinal trials to support the detailed advantages of muscle oximetry utilization in sports science.

Quantitative clinical nonpulsatile and localized visible light oximeter: design of the T-Stat tissue oximeter

NASA Astrophysics Data System (ADS)

Benaron, David A.; Parachikov, Ilian H.; Cheong, Wai-Fung; Friedland, Shai; Duckworth, Joshua L.; Otten, David M.; Rubinsky, Boris E.; Horchner, Uwe B.; Kermit, Eben L.; Liu, Frank W.; Levinson, Carl J.; Murphy, Aileen L.; Price, John W.; Talmi, Yair; Weersing, James P.

2003-07-01

We report the development of a general, quantitative, and localized visible light clinical tissue oximeter, sensitive to both hypoxemia and ischemia. Monitor design and operation were optimized over four instrument generations. A range of clinical probes were developed, including non-contact wands, invasive catheters, and penetrating needles with injection ports. Real-time data were collected (a) from probes, standards, and reference solutions to optimize each component, (b) from ex vivo hemoglobin solutions co-analyzed for StO2% and pO2 during deoxygenation, and (c) from normoxic human subject skin and mucosal tissue surfaces. Results show that (a) differential spectroscopy allows extraction of features with minimization of the effects of scattering, (b) in vitro oximetry produces a hemoglobin saturation binding curve of expected sigmoid shape and values, and (c) that monitoring human tissues allows real-time tissue spectroscopic features to be monitored. Unlike with near-infrared (NIRS) or pulse oximetry (SpO2%) methods, we found non-pulsatile, diffusion-based tissue oximetry (StO2%) to work most reliably for non-contact reflectance monitoring and for invasive catheter- or needle-based monitoring, using blue to orange light (475-600 nm). Measured values were insensitive to motion artifact. Down time was non-existent. We conclude that the T-Stat oximeter design is suitable for the collection of spectroscopic data from human subjects, and that the oximeter may have application in the monitoring of regional hemoglobin oxygen saturation in the capillary tissue spaces of human subjects.

Noncontact simultaneous dual wavelength photoplethysmography: A further step toward noncontact pulse oximetry

NASA Astrophysics Data System (ADS)

Humphreys, Kenneth; Ward, Tomas; Markham, Charles

2007-04-01

We present a camera-based device capable of capturing two photoplethysmographic (PPG) signals at two different wavelengths simultaneously, in a remote noncontact manner. The system comprises a complementary metal-oxide semiconductor camera and dual wavelength array of light emitting diodes (760 and 880nm). By alternately illuminating a region of tissue with each wavelength of light, and detecting the backscattered photons with the camera at a rate of 16frames/wavelengths, two multiplexed PPG wave forms are simultaneously captured. This process is the basis of pulse oximetry, and we describe how, with the inclusion of a calibration procedure, this system could be used as a noncontact pulse oximeter to measure arterial oxygen saturation (SpO2) remotely. Results from an experiment on ten subjects, exhibiting normal SpO2 readings, that demonstrate the instrument's ability to capture signals from a range of subjects under realistic lighting and environmental conditions are presented. We compare the signals captured by the noncontact system to a conventional PPG signal captured concurrently from a finger, and show by means of a J. Bland and D. Altman [Lancet 327, 307 (1986); Statistician 32, 307 (1983)] test, the noncontact device to be comparable to a contact device as a monitor of heart rate. We highlight some considerations that should be made when using camera-based "integrative" sampling methods and demonstrate through simulation, the suitability of the captured PPG signals for application of existing pulse oximetry calibration procedures.

Does the estimation of light attenuation in tissue increase the accuracy of reflectance pulse oximetry at low oxygen saturations in vivo?

PubMed

Kisch-Wedel, H; Bernreuter, P; Kemming, G; Albert, M; Zwissler, B

2009-09-01

A new technique was validated in vivo in reflectance pulse oximetry for measuring low oxygen saturations. Two pairs of light emitter/detector diodes allow for estimation of light attenuation (LA) in tissue, which is assumed to be responsible for the inaccuracy of pulse oximetry at less than 70 % arterial oxygen saturation. For validation, 17 newborn piglets were desaturated stepwise from 21 % to 1.25 % inspiratory oxygen concentration during general anesthesia, and arterial oxygen saturation was measured with the reflectance pulse oximeter adjusted for LA in tissue, with a standard transmission pulse oximeter and a hemoximeter. LA in tissue could be quantified and was different between snout and foreleg (probability level (p) < 0.05). At arterial oxygen saturations above 70 %, the bias between the methods was at 0 %-1 % and the variability 4 %-5 %. From 2 % to 100 % arterial oxygen saturation, the reflectance pulse oximeter estimated oxyhemoglobin saturation more accurately than a conventional transmission pulse oximeter (p < 0.05). At low oxygen saturations below 70 %, the bias and variability of the reflectance pulse oximeter calibration were closer to the hemoximeter measurements than the transmission pulse oximeter (p < 0.05). The variability of the reflectance pulse oximeter was slightly lower than the traditional oximeter by taking into account the LA in tissue (9 % versus 11 % -15 %, ns), and thus, the quality of the individual calibration lines improved (correlation coefficient, p < 0.05).

Nano-emulsions of fluorinated trityl radicals as sensors for EPR oximetry

NASA Astrophysics Data System (ADS)

Charlier, N.; Driesschaert, B.; Wauthoz, N.; Beghein, N.; Préat, V.; Amighi, K.; Marchand-Brynaert, J.; Gallez, B.

2009-04-01

This article reports the development and evaluation of two nano-emulsions (F45T-03/HFB and F15T-03/PFOB) containing fluorinated trityl radicals dissolved in perfluorocarbons. Preparation with a high-pressure homogenizer conferred sub-micronic size to both nano-emulsions. In vitro and in vivo EPR spectroscopy showed that the nano-emulsions had much greater oxygen sensitivity than the hydrophilic trityl, CT-03. In vivo experiments in rodents confirmed the ability of the nano-emulsions to follow the changes in oxygen concentration after induced ischemia. Histological evaluation of the tissue injected with the nano-emulsions revealed some acute toxicity for the F45T-03/HFB nano-emulsion but none for the F15T-03/PFOB nano-emulsion. These new formulations should be considered for further EPR oximetry experiments in pathophysiological situations where subtle changes in tissue oxygenation are expected.

New laser system for highly sensitive clinical pulse oximetry

NASA Astrophysics Data System (ADS)

Hamza, Mostafa; Hamza, Mohammad

1996-04-01

This paper describes the theory and design of a new pulse oximeter in which laser diodes and other compact laser sources are used for the measurement of oxygen saturation in patients who are at risk of developing hypoxemia. The technique depends upon illuminating special sites of the skin of the patient with radiation from modulated laser sources at selected wavelengths. The specific laser wavelengths are chosen based on the absorption characteristics of oxyhemoglobin, reduced hemoglobin and other interfering sources for obtaining more accurate measurements. The laser radiation transmitted through the tissue is detected and signal processing based on differential absorption laser spectroscopy is done in such a way to overcome the primary performance limitations of the conventionally used pulse oximetry. The new laser pulse oximeter can detect weak signals and is not affected by other light sources such as surgical lamps, phototherapy units, etc. The detailed description and operating characteristics of this system are presented.

All-organic optoelectronic sensor for pulse oximetry

NASA Astrophysics Data System (ADS)

Lochner, Claire M.; Khan, Yasser; Pierre, Adrien; Arias, Ana C.

2014-12-01

Pulse oximetry is a ubiquitous non-invasive medical sensing method for measuring pulse rate and arterial blood oxygenation. Conventional pulse oximeters use expensive optoelectronic components that restrict sensing locations to finger tips or ear lobes due to their rigid form and area-scaling complexity. In this work, we report a pulse oximeter sensor based on organic materials, which are compatible with flexible substrates. Green (532 nm) and red (626 nm) organic light-emitting diodes (OLEDs) are used with an organic photodiode (OPD) sensitive at the aforementioned wavelengths. The sensor’s active layers are deposited from solution-processed materials via spin-coating and printing techniques. The all-organic optoelectronic oximeter sensor is interfaced with conventional electronics at 1 kHz and the acquired pulse rate and oxygenation are calibrated and compared with a commercially available oximeter. The organic sensor accurately measures pulse rate and oxygenation with errors of 1% and 2%, respectively.

Trityl radicals in perfluorocarbon emulsions as stable, sensitive, and biocompatible oximetry probes.

PubMed

Dhimitruka, Ilirian; Alzarie, Yasmin Alsayed; Hemann, Craig; Samouilov, Alexandre; Zweier, Jay L

2016-12-01

EPR oximetry with the use of trityl radicals can enable sensitive O 2 measurement in biological cells and tissues. However, in vitro cellular and in vivo biological applications are limited by rapid trityl probe degradation or biological clearance and the need to enhance probe O 2 sensitivity. We synthesized novel perfluorocarbon (PFC) emulsions, ∼200nm droplet size, containing esterified perchlorinated triphenyl methyl (PTM) radicals dispersed in physiological aqueous buffers. These formulations exhibit excellent EPR signal stability, over 20-fold greater than free PTM probes, with high oxygen sensitivity ∼17mG/mmHg enabling pO 2 measurement in aqueous solutions or cell suspensions with sensitivity >0.5mmHg. Thus, PFC-PTM probes hold great promise to enable combined O 2 delivery and sensing as needed to restore or enhance tissue oxygenation in disease. Copyright © 2016 Elsevier Ltd. All rights reserved.

Comparative Study of Pulp Vitality in Primary and Young Permanent Molars in Human Children with Pulse Oximeter and Electric Pulp Tester.

PubMed

Shahi, Prinka; Sood, P B; Sharma, Arun; Madan, Manish; Shahi, Nishat; Gandhi, Geetanjali

2015-01-01

The purpose of this study was to compare the pulp testing methods (pulse oximetry and electric pulp test) in primary and young permanent teeth of children. The study included a total of 155 children aged 4 to 15 years. Twenty children formed control group I. Study group included all healthy, 85 primary 2nd molars in group II and 85 permanent 1st molars in group III. Fifty children needing endodontics treatment formed test group IV. The readings were recorded as true positive (TP), false positive (FP), true negative (TN), false negative (FN). Based on this, the sensitivity, specificity, positive predictive value and negative predictive value were calculated for each method. The results were statistically analyzed using Chi-square test. On comparing pulse oximetry with electric pulp test 'p-value' was found to be 0.487 and 1.00 for groups 1 and 2 respectively and was statistically not significant. Whereas 'p-value' for groups 3 and 4 was < 0.0001 and 0.003 respectively and was statistically highly significant. The present study indicates that pulse oximetry can be used as a routine method for assessing the pulp vitality in primary, young permanent and mature permanent teeth. How to cite this article: Shahi P, Sood PB, Sharma A, Madan M, Shahi N, Gandhi G. Comparative Study of Pulp Vitality in Primary and Young Permanent Molars in Human Children with Pulse Oximeter and Electric Pulp Tester. Int J Clin Pediatr Dent 2015;8(2):94-98.

Lifebox pulse oximeter implementation in Malawi: evaluation of educational outcomes and impact on oxygen desaturation episodes during anaesthesia.

PubMed

Albert, V; Mndolo, S; Harrison, E M; O'Sullivan, E; Wilson, I H; Walker, I A

2017-06-01

Pulse oximetry is an essential monitor for safe anaesthesia but is often not available in low-income countries. The aim of this study was to determine whether the introduction of pulse oximetry with training was feasible and could reduce the incidence of oxygen desaturation during anaesthesia in a low-income country. Pulse oximeters were donated, with training, to 83 non-physician anaesthetists in Malawi. Knowledge was tested immediately before and after training and at follow-up. Providers were asked to record the lowest peripheral oxygen saturation (SpO 2 ) for the first 100 cases anaesthetised after training. The primary clinical outcome was the proportion of cases with an oxygen desaturation event (SpO 2 < 90%). Seventy-seven of 83 (93%) participants completed all pre- and post-training tests. Pulse oximetry knowledge improved after training from a median (IQR [range]) score of 39 (37-42 [28-48]) to 44 (42-46 [35-50]) and this knowledge was maintained for 8 months (p < 0.001). Oxygen saturation data and provider responses were recorded for 4772 cases. The proportion of oxygen desaturation episodes decreased from 17.2% to 6.5%, representing a 36% reduction in the odds of an oxygen desaturation event in the second 50 cases compared with the first 50 (OR 0.64, 95%CI 0.50-0.82, p < 0.001). We conclude that donation of pulse oximeters, with training, in Malawi was feasible, improved knowledge and reduced the incidence of oxygen desaturation events. © 2017 The Association of Anaesthetists of Great Britain and Ireland.

An audit of the use of an opiate sparing, multimodal analgesic regime in children with Sleep Disordered Breathing/Obstructive Sleep Apnoea undergoing adenotonsillectomy.

PubMed

Hack, Henrik

2014-01-01

Children with Sleep Disordered Breathing/Obstructive Sleep Apnoea have an increased incidence of respiratory complications following adenotonsillectomy. This may be partly related to an increase in sensitivity to opiates. An audit of such cases undergoing adenotonsillectomy was performed with the following aims: All patients had Sleep Disordered Breathing/Obstructive Sleep Apnoea confirmed preoperatively by Overnight Oximetry Studies. Oximetry data was expressed as the lowest recorded saturation (SpO2 Low %) and number of significant desaturations (see text) per hour (ODI4%). Case notes and oximetry studies were scrutinized for relevant perioperative anaesthetic and analgesic data, risk factors and complications. The overall incidence of major and minor respiratory complications was low (1.6% and 27% respectively). Children who suffered any complication were more likely to be younger (p=0.0078), have a lower SpO2 Low (p=0.004) and higher ODI4% (p=<0.0001). Multiple logistic regression showed ODI4% to be the best predictor of a potential respiratory complication (p=0.0032). An ODI4% of >8 may be the best cut off point in predicting complications (AUC=0.78, sensitivity=0.90) but it showed a poor specificity (0.57). Primary/secondary haemorrhage occurred in 0.4%/1.2% respectively and postoperative nausea and vomiting in 4.4%. A low dose opiate-based, multi modal analgesic regime appears to be effective and safe in children with Sleep Disordered Breathing/Obstructive Sleep Apnoea undergoing adenotonsillectomy. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

ROx3: Retinal oximetry utilizing the blue-green oximetry method

NASA Astrophysics Data System (ADS)

Parsons, Jennifer Kathleen Hendryx

The ROx is a retinal oximeter under development with the purpose of non-invasively and accurately measuring oxygen saturation (SO2) in vivo. It is novel in that it utilizes the blue-green oximetry technique with on-axis illumination. ROx calibration tests were performed by inducing hypoxia in live anesthetized swine and comparing ROx measurements to SO 2 values measured by a CO-Oximeter. Calibration was not achieved to the precision required for clinical use, but limiting factors were identified and improved. The ROx was used in a set of sepsis experiments on live pigs with the intention of tracking retinal SO2 during the development of sepsis. Though conclusions are qualitative due to insufficient calibration of the device, retinal venous SO2 is shown to trend generally with central venous SO2 as sepsis develops. The novel sepsis model developed in these experiments is also described. The method of cecal ligation and perforation with additional soiling of the abdomen consistently produced controllable severe sepsis/septic shock in a matter of hours. In addition, the ROx was used to collect retinal images from a healthy human volunteer. These experiments served as a bench test for several of the additions/modifications made to the ROx. This set of experiments specifically served to illuminate problems with various light paths and image acquisition. The analysis procedure for the ROx is under development, particularly automating the process for consistency, accuracy, and time efficiency. The current stage of automation is explained, including data acquisition processes and the automated vessel fit routine. Suggestions for the next generation of device minimization are also described.

Effect of a topical vasodilator on tumor hypoxia and tumor oxygen guided radiotherapy using EPR oximetry.

PubMed

Hou, Huagang; Abramovic, Zrinka; Lariviere, Jean P; Sentjurc, Marjeta; Swartz, Harold; Khan, Nadeem

2010-05-01

We sought to reduce tumor hypoxia by topical application of a vasodilator, benzyl nicotinate (BN), and investigated its effect on the growth of tumors irradiated at times when tumor pO(2) increased. EPR oximetry was used to follow the changes in the tissue pO(2) of subcutaneous radiation-induced fibrosarcoma (RIF-1) tumors during topical applications of 1.25-8% BN formulations for 5 consecutive days. The RIF-1 tumors were hypoxic with a tissue pO(2) of 4.6-7.0 mmHg. A significant increase in tumor pO(2) occurred 10-30 min after BN application. The formulation with the minimal BN concentration that produced a significant increase in tumor pO(2) was used for the radiation study. The tumors were irradiated (4 Gy x 5) at the time of the maximum increase in pO(2) observed with the 2.5% BN formulation. The tumors with an increase in pO(2) of greater than 2 mmHg from the baseline after application of BN on day 1 had a significant growth inhibition compared to the tumors with an increase in pO(2) of less than 2 mmHg. The results indicate that the irradiation of tumors at the time of an increase in pO(2) after the topical application of the 2.5% BN formulation led to a significant growth inhibition. EPR oximetry provided dynamic information on the changes in tumor pO(2), which could be used to identify responders and non-responders and schedule therapy during the experiments.

Accuracy of smartphone apps for heart rate measurement.

PubMed

Coppetti, Thomas; Brauchlin, Andreas; Müggler, Simon; Attinger-Toller, Adrian; Templin, Christian; Schönrath, Felix; Hellermann, Jens; Lüscher, Thomas F; Biaggi, Patric; Wyss, Christophe A

2017-08-01

Background Smartphone manufacturers offer mobile health monitoring technology to their customers, including apps using the built-in camera for heart rate assessment. This study aimed to test the diagnostic accuracy of such heart rate measuring apps in clinical practice. Methods The feasibility and accuracy of measuring heart rate was tested on four commercially available apps using both iPhone 4 and iPhone 5. 'Instant Heart Rate' (IHR) and 'Heart Fitness' (HF) work with contact photoplethysmography (contact of fingertip to built-in camera), while 'Whats My Heart Rate' (WMH) and 'Cardiio Version' (CAR) work with non-contact photoplethysmography. The measurements were compared to electrocardiogram and pulse oximetry-derived heart rate. Results Heart rate measurement using app-based photoplethysmography was performed on 108 randomly selected patients. The electrocardiogram-derived heart rate correlated well with pulse oximetry ( r = 0.92), IHR ( r = 0.83) and HF ( r = 0.96), but somewhat less with WMH ( r = 0.62) and CAR ( r = 0.60). The accuracy of app-measured heart rate as compared to electrocardiogram, reported as mean absolute error (in bpm ± standard error) was 2 ± 0.35 (pulse oximetry), 4.5 ± 1.1 (IHR), 2 ± 0.5 (HF), 7.1 ± 1.4 (WMH) and 8.1 ± 1.4 (CAR). Conclusions We found substantial performance differences between the four studied heart rate measuring apps. The two contact photoplethysmography-based apps had higher feasibility and better accuracy for heart rate measurement than the two non-contact photoplethysmography-based apps.

The Relationship between Oxygen Saturation and Color Alteration of a Compromised Skin Flap: Experimental Study on the Rabbit.

PubMed

Prasetyono, Theddeus O H; Adianto, Senja

2013-09-01

The aim of this study was to collect important data on the time of oxygen saturation change in relation to skin flap color alteration using non-invasive pulse oximetry to evaluate its ability to provide continuous monitoring of skin flap perfusion. An experimental study on the monitoring of blood perfusion of 20 tube-island groin flaps of 10 male New Zealand rabbits was performed using pulse oximetry. The animals were randomly assigned to one of two groups representing a blockage of either arterial or venous blood flow. The oxygen saturation change and clinical color alteration were monitored from the beginning of vessel clamping until the saturation became undetectable. The result was analyzed by the t-test using SSPS ver. 10.0. The mean times from the vessel clamping until the saturation became undetectable were 20.19±2.13 seconds and 74.91±10.57 seconds for the artery and vein clamping groups, respectively. The mean time of the clinical alteration from the beginning of vein clamping was 34.5±11.72 minutes, while the alteration in flaps with artery clamping could not be detected until 2.5 hours after clamping. The use of neonate-type reusable flex sensor-pulse oximetry is objective and effective in early detection of arterial and vein blockage. It provides real-time data on vessel occlusion, which in turn will allow for early salvaging. The detection periods of both arterial occlusion and venous congestion are much earlier than the color alteration one may encounter clinically.

Overload and neovascularization of Achilles tendons in young artistic and rhythmic gymnasts compared with controls: an observational study.

PubMed

Notarnicola, A; Maccagnano, G; Di Leo, M; Tafuri, S; Moretti, B

2014-08-01

The incidence of Achilles tendinopathy is very high in young female gymnasts (17.5 %). According to literature, ecography screenings show the tendons thickening, but at the same time it does not reveal a direct link to the clinical picture. The neovessels are involved in the pathophysiological process of Achilles tendinopathy. For this reason, we wanted to verify there between perfusion tendon values and the type of sport activity. We performed a clinical observational study monitoring the oximetry of the Achilles tendon and the epidemiological data of 52 elite female (artistic and rhythmic) gymnasts versus 21 age-matched controls. Analyzing the main limb, we revealed statistically higher oximetry values in the artistic gymnasts group (69.5 %) compared to the rhythmic gymnasts group (67.1 %) (t = 2.13; p = 0.01) and the sedentary group (66.2 %) (t = 2.70; p = 0.004), but we did not find any differences between rhythmic gymnasts group and the sedentary group (t = 0.68; p = 0.24). The multiple logistic regression model highlighted that the oximetry value of the main limb is not influenced by age, knowledge of the main limb, years of general and gymnastic sports activity (p > 0.05). We discovered an increase of Achilles tendon perfusion in the main limb in the artistic gymnast group. We hypothesize that specific figures of artistic sports activity are responsible for muscle overload and gastrocnemius-soleus group and, at the same time, these figures cause hyperperfusion of the tendon. Prospective longitudinal studies could explain if this could become a predictive sign of the next Achilles tendinopathy onset.

Correlation between clinical severity and different non-invasive measurements of carbon monoxide concentration: A population study

PubMed Central

Desseaux, Kristell; Chevret, Sylvie

2017-01-01

Objectives Carbon monoxide (CO) poisoning is a major concern in industrialized countries. Each year, thousands of victims, resulting in approximately 100 fatalities, are encountered in France. The diagnosis of CO poisoning is challenging; while carboxyhemoglobin (COHb) may be useful, it is a weak indicator of the severity of CO poisoning. This weak indicator may be a result of the delay between poisoning occurrence and the blood assay. Two apparatuses, CO oximeters and exhaled CO analyzers, now permit COHb to be determined outside hospitals. Our hypothesis is that these instruments allow the early measurement of COHb concentrations, which are more correlated with the severity of poisoning, expressed using the poisoning severity score (PSS). Design In an observational and retrospective cohort study, the distribution of COHb measurements obtained by CO oximetry or by exhaled CO analyzers was compared between groups of severity expressed using the PSS. Setting Data were collected in the Paris area from January 2006 to December 2010 by the French Surveillance System of CO poisoning. Participants All patients with CO poisoning reported to the French Surveillance System of CO poisoning. Results There was a significant difference in the COHb values obtained by CO oximetry between groups stratified according to PSS (p<0.0001). A significant difference in the values of exhaled CO was also observed between PSS groups (p = 0.006), although the relationship was not linear. Conclusions The COHb concentrations measured using CO oximetry, but not those measured using exhaled CO analyzers, were well correlated with the severity of CO poisoning. PMID:28350859

Efficacy of Opioid-free Anesthesia in Reducing Postoperative Respiratory Depression in Children Undergoing Tonsillectomy

ClinicalTrials.gov

2018-05-04

Anesthesia; General Anesthesia; Analgesics, Opioid; Postoperative Complications; Pathologic Processes; Physiologic Effects of Drugs; Narcotics; Analgesics; Sleep Disordered Breathing; Obstructive Sleep Apnea of Child; Tonsillectomy; Respiratory Depression; Dexmedetomidine; Ketamine; Lidocaine; Gabapentin; Pulse Oximetry

The accuracy of pulse oximetry in emergency department patients with severe sepsis and septic shock: a retrospective cohort study.

PubMed

Wilson, Ben J; Cowan, Hamish J; Lord, Jason A; Zuege, Dan J; Zygun, David A

2010-05-05

Pulse oximetry is routinely used to continuously and noninvasively monitor arterial oxygen saturation (SaO2) in critically ill patients. Although pulse oximeter oxygen saturation (SpO2) has been studied in several patient populations, including the critically ill, its accuracy has never been studied in emergency department (ED) patients with severe sepsis and septic shock. Sepsis results in characteristic microcirculatory derangements that could theoretically affect pulse oximeter accuracy. The purposes of the present study were twofold: 1) to determine the accuracy of pulse oximetry relative to SaO2 obtained from ABG in ED patients with severe sepsis and septic shock, and 2) to assess the impact of specific physiologic factors on this accuracy. This analysis consisted of a retrospective cohort of 88 consecutive ED patients with severe sepsis who had a simultaneous arterial blood gas and an SpO2 value recorded. Adult ICU patients that were admitted from any Calgary Health Region adult ED with a pre-specified, sepsis-related admission diagnosis between October 1, 2005 and September 30, 2006, were identified. Accuracy (SpO2 - SaO2) was analyzed by the method of Bland and Altman. The effects of hypoxemia, acidosis, hyperlactatemia, anemia, and the use of vasoactive drugs on bias were determined. The cohort consisted of 88 subjects, with a mean age of 57 years (19 - 89). The mean difference (SpO2 - SaO2) was 2.75% and the standard deviation of the differences was 3.1%. Subgroup analysis demonstrated that hypoxemia (SaO2 < 90) significantly affected pulse oximeter accuracy. The mean difference was 4.9% in hypoxemic patients and 1.89% in non-hypoxemic patients (p < 0.004). In 50% (11/22) of cases in which SpO2 was in the 90-93% range the SaO2 was <90%. Though pulse oximeter accuracy was not affected by acidoisis, hyperlactatementa, anemia or vasoactive drugs, these factors worsened precision. Pulse oximetry overestimates ABG-determined SaO2 by a mean of 2.75% in emergency department patients with severe sepsis and septic shock. This overestimation is exacerbated by the presence of hypoxemia. When SaO2 needs to be determined with a high degree of accuracy arterial blood gases are recommended.

Pre-clinical evaluation of OxyChip for long-term EPR oximetry.

PubMed

Hou, Huagang; Khan, Nadeem; Gohain, Sangeeta; Kuppusamy, M Lakshmi; Kuppusamy, Periannan

2018-03-16

Tissue oxygenation is a critical parameter in various pathophysiological situations including cardiovascular disease and cancer. Hypoxia can significantly influence the prognosis of solid malignancies and the efficacy of their treatment by radiation or chemotherapy. Electron paramagnetic resonance (EPR) oximetry is a reliable method for repeatedly assessing and monitoring oxygen levels in tissues. Lithium octa-n-butoxynaphthalocyanine (LiNc-BuO) has been developed as a probe for biological EPR oximetry, especially for clinical use. However, clinical applicability of LiNc-BuO crystals is hampered by potential limitations associated with biocompatibility, biodegradation, or migration of individual bare crystals in tissue. To overcome these limitations, we have embedded LiNc-BuO crystals in polydimethylsiloxane (PDMS), an oxygen-permeable biocompatible polymer and developed an implantable/retrievable form of chip, called OxyChip. The chip was optimized for maximum spin density (40% w/w of LiNc-BuO in PDMS) and fabricated in a form suitable for implantation using an 18-G syringe needle. In vitro evaluation of the OxyChip showed that it is robust and highly oxygen sensitive. The dependence of its EPR linewidth to oxygen was linear and highly reproducible. In vivo efficacy of the OxyChip was evaluated by implanting it in rat femoris muscle and following its response to tissue oxygenation for up to 12 months. The results revealed preservation of the integrity (size and shape) and calibration (oxygen sensitivity) of the OxyChip throughout the implantation period. Further, no inflammatory or adverse reaction around the implantation area was observed thereby establishing its biocompatibility and safety. Overall, the results demonstrated that the newly-fabricated high-sensitive OxyChip is capable of providing long-term measurements of oxygen concentration in a reliable and repeated manner under clinical conditions.

Assessment of the Changes in 9L and C6 Glioma pO2 by EPR Oximetry as a Prognostic Indicator of Differential Response to Radiotherapy

PubMed Central

Hou, Huagang; Mupparaju, Sriram P.; Lariviere, Jean P.; Hodge, Sassan; Gui, Jiang; Swartz, Harold M.; Khan, Nadeem

2013-01-01

Tumor hypoxia impedes the outcome of radiotherapy. As the extent of hypoxia in solid tumors varies during the course of radiotherapy, methods that can provide repeated assessment of tumor pO2 such as EPR oximetry may enhance the efficacy of radiotherapy by scheduling irradiations when the tumors are oxygenated. The repeated measurements of tumor pO2 may also identify responders, and thereby facilitate the design of better treatment plans for nonresponding tumors. We have investigated the temporal changes in the ectopic 9L and C6 glioma pO2 irradiated with single radiation doses less than 10 Gy by EPR oximetry. The 9L and C6 tumors were hypoxic with pO2 of approximately 5–9 mmHg. The pO2 of C6 tumors increased significantly with irradiation of 4.8–9.3 Gy. However, no change in the 9L tumor pO2 was observed. The irradiation of the oxygenated C6 tumors with a second dose of 4.8 Gy resulted in a significant delay in growth compared to hypoxic and 2 Gy × 5 treatment groups. The C6 tumors with an increase in pO2 of greater than 50% from the baseline of irradiation with 4.8 Gy (responders) had a significant tumor growth delay compared to nonresponders. These results indicate that the ectopic 9L and C6 tumors responded differently to radiotherapy. We propose that the repeated measurement of the oxygen levels in the tumors during radiotherapy can be used to identify responders and to design tumor oxygen guided treatment plans to improve the outcome. PMID:23391148

An applicable approach for extracting human heart rate and oxygen saturation during physical movements using a multi-wavelength illumination optoelectronic sensor system

NASA Astrophysics Data System (ADS)

Alharbi, Samah; Hu, Sijung; Mulvaney, David; Blanos, Panagiotis

2018-02-01

The ability to gather physiological parameters such as heart rate (HR) and oxygen saturation (SpO2%) during physical movement allows to continuously monitor personal health status without disrupt their normal daily activities. Photoplethysmography (PPG) based pulse oximetry and similar principle devices are unable to extract the HR and SpO2% reliably during physical movement due to interference in the signals that arise from motion artefacts (MAs). In this research, a flexible reflectance multi-wavelength optoelectronic patch sensor (OEPS) has been developed to overcome the susceptibility of conventional pulse oximetry readings to MAs. The OEPS incorporates light embittered diodes as illumination sources with four different wavelengths, e.g. green, orange, red, and infrared unlike the conventional pulse oximetry devices that normally measure the skin absorption of only two wavelengths (red and infrared). The additional green and orange wavelengths were found to be distinguish to the absorption of deoxyhemoglobin (RHb) and oxyhemoglobin (HbO2). The reliability of extracting physiological parameters from the green and orange wavelengths is due to absorbed near to the surface of the skin, thereby shortening the optical path and so effectively reducing the influence of physical movements. To compensate of MAs, a three-axis accelerometer was used as a reference with help of adaptive filter to reduce MAs. The experiments were performed using 15 healthy subjects aged 20 to 30. The primary results show that there are no significant difference of heart rate and oxygen saturation measurements between commercial devices and OEPS Green (r=0.992), Orange(r=0.984), Red(r=0.952) and IR(r=0.97) and SpO2% (r = 0.982, p = 0.894).

Evaluation of multiple modes of oximetry monitoring as an index of splanchnic blood flow in a newborn lamb model of hypoxic, ischemic, and hemorrhagic stress.

PubMed

Applegate, Richard L; Ramsingh, Davinder S; Dorotta, Ihab; Sanghvi, Chirag; Blood, Arlin B

2013-06-01

Early and aggressive treatment of circulatory failure is associated with increased survival, highlighting the need for monitoring methods capable of early detection. Vasoconstriction and decreased oxygenation of the splanchnic circulation are a sentinel response of the cardiovasculature during circulatory distress. Thus, we measured esophageal oxygenation as an index of decreased tissue oxygen delivery caused by three types of ischemic insult, occlusive decreases in mesenteric blood flow, and hemodynamic adaptations to systemic hypoxia and simulated hemorrhagic stress. Five anesthetized lambs were instrumented for monitoring of mean arterial pressure, mesenteric artery blood flow, central venous hemoglobin oxygen saturation, and esophageal and buccal microvascular hemoglobin oxygen saturation (StO2). The sensitivities of oximetry monitoring to detect cardiovascular insult were assessed by observing responses to graded occlusion of the descending aorta, systemic hypoxia due to decreased FIO2, and acute hemorrhage. Decreases in mesenteric artery flow during aortic occlusions were correlated with decreased esophageal StO2 (R = 0.41). During hypoxia, esophageal StO2 decreased significantly within 1 min of initiation, whereas buccal StO2 decreased within 3 min, and central venous saturation did not change significantly. All modes of oximetry monitoring and arterial blood pressure were correlated with mesenteric artery flow during acute hemorrhage. Esophageal StO2 demonstrated a greater decrease from baseline levels as well as a more rapid return to baseline levels during reinfusion of the withdrawn blood. These experiments suggest that monitoring esophageal StO2 may be useful in the detection of decreased mesenteric oxygen delivery as may occur in conditions associated with hypoperfusion or hypoxia.

Oxygen saturation in the dental pulp of permanent teeth: a critical review.

PubMed

Bruno, Kely Firmino; Barletta, Fernando Branco; Felippe, Wilson Tadeu; Silva, Júlio Almeida; Gonçalves de Alencar, Ana Helena; Estrela, Carlos

2014-08-01

Pulse oximetry is a noninvasive method for assessing vascular health based on oxygen saturation level. The method has recently also been used to assess dental pulp vitality, but a median oxygen saturation level suggestive of normal pulp physiology has not been determined. The objective of this study was to make a critical analysis of the published research to establish the median oxygen saturation for the diagnosis of normal dental pulps in maxillary anterior permanent teeth using pulse oximetry. Studies reporting on the use of pulse oximeters to determine oxygen saturation in dental pulps were retrieved using the MEDLINE, Scientific Electronic Library Online, and Cochrane Central Register of Controlled Trials databases plus a manual search of relevant references cited by selected articles. Different combinations of the terms "oximetry," "oximeter," "pulp," "dental," and "dentistry" were used in the search. Statistical analysis was performed for each group of teeth (central incisors, lateral incisors, and canines) using R statistical software (US EPA ORD NHEERL, Corvallis, OR) and a random effects model (P < .0001) with an I(2) of 99%. Of the 295 articles found, only 6 met the inclusion criteria (472 teeth). Of these, the number of articles included in each analysis (according to tooth group) was as follows: all 6 studies (288 teeth) for central incisors at a median oxygen saturation of 87.73%, 3 studies (90 teeth) for lateral incisors at a median oxygen saturation of 87.24%, and 4 studies (94 teeth) for canines at a median oxygen saturation of 87.26%. The median oxygen saturation in normal dental pulps of permanent central incisors, lateral incisors, and canines was higher than 87%. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Correlation of fetal oxygen saturation to fetal heart rate patterns. Evaluation of fetal pulse oximetry with two different oxisensors.

PubMed

Luttkus, A K; Friedmann, W; Homm-Luttkus, C; Dudenhausen, J W

1998-03-01

The purpose of this study was the correlation of fetal oxygen saturation values to various fetal heart rate patterns, as well as to oxygen saturation values obtained by fetal blood analysis. These objectives need to be evaluated from the perspective that two generations of fetal oxisensors have been used. Two different oxisensor systems (FS10: 660+890 nm and FS14: 735+890 nm) and a blinded pulse oximeter (type N400, Nellcor Puritan Bennett) were utilized to monitor 112 fetuses. All data, including oxygen saturation, fetal heart rate patterns, signal and contact quality were stored on a personal computer and evaluated after delivery. The following median fetal oxygen saturation values were obtained: during reassuring fetal heart rate sequences 54% with the oxisensor FS10 and 48% with the newer FS14 oxisensor, during intervals of variable decelerations 43% with the FS10 oxisensor and 40% with the FS14 oxisensor. These differences between values obtained during normal and abnormal fetal heart rate patterns are significant. Due to non-reassuring fetal heart rate patterns 81 fetal blood analyses were performed. The values of pulse oximetry were 9% higher (6% for the FS14) than those of spectrophotometry. Correlation of both methods was r=0.66 (0.74 for the FS14). In combination with fetal heart rate monitoring, fetal pulse oximetry promises a better differentiation between low and high risk heart rate patterns. Oxygen saturation values from intermittent fetal blood sampling reassure the clinician concerning the accuracy of this new method of intrapartum fetal surveillance and underline the increased quality of the new generation of oxisensor using light of a wavelength of 735 and 890 nm.

[Angiography: safety x economy].

PubMed

Torres, Rogil José de Almeida; Muccioli, Cristina; Casella, Antonio Marcelo Barbante; Regonha, Eduardo; Luchini, Andréa; Weiss, Wilma; Frecceiro, Paulo Roberto

2006-01-01

To evaluate the safety, effectiveness, and cost of angiofluoresceinographic examination by using both the least amount of dye as well as digital equipment along with a laser photocopier. Prospective and comparative study carried out in a group of 70 patients, who underwent an angiographic evaluation with a conventional retinographer injecting 5 ml sodium fluorescein at 10% (control group) as well as a group of 70 patients who underwent an angiographic evaluation with a digital retinographer injecting 2 ml fluorescein at 10% (study group). Arterial pressure, heart rate and oximetry were assessed prior to and after the dye injection. Organic reactions related to the examination were reported. Photograph quality as well as cost between the two techniques were compared. Control group patients showed a greater increase in systolic and diastolic arterial pressure. Heart rate, oximetry measurement and adverse reactions did not show any significant statistical differences between both groups. As for the quality of photographs, a better performance was noticed in the control group. As for the cost, the examination carried out in the study group required lower cost and thus saved around 54.8% per examination in relation to the control group. The examination carried out with a lower dose of fluorescein using digital equipment along with a laser photocopier provided greater stability in the systolic and diastolic arterial pressure. However, it did not have any influence on heart rate, oximetry or adverse reactions such as nausea, vomiting, syncope and rashes. The quality of photographs was poor although they enabled diagnosis as well as therapy follow-up for those who carried out the examination. Moreover, economically the above procedure represented a gain of 66.26%, against 25.81% in relation to the conventional equipment.

Diagnosis and prediction of the occurrence of acute mountain sickness measuring oxygen saturation--independent of absolute altitude?

PubMed

Leichtfried, Veronika; Basic, Daniel; Burtscher, Martin; Gothe, Raffaella Matteucci; Siebert, Uwe; Schobersberger, Wolfgang

2016-03-01

Commercialization of trekking tourism enables untrained persons to participate in trekking tours. Because hypoxia is one of the main purported triggers for acute mountain sickness (AMS), pulse oximetry, which measures arterial oxygen saturation (SPO2), is discussed to be a possible and useful tool for the diagnosis of AMS. The purpose of this study was to evaluate possible associations between SPO2 values and the occurrence of AMS. In 204 trekkers, SPO2 values (pulse oximetry) were measured and the Lake Louise Self-assessment Score (LLS) was administered over the first 7 days of their trekking tours. During treks at altitudes of 2500-5500 m in Nepal, India, Africa, and South America, 100 participants suffered from mild AMS, 3 participants suffered from severe AMS, and 9 participants reported both mild and severe AMS. The lowest mean SPO2 was 85.5 (95 % confidence interval (CI), 83.9-86.1 %) on day 5. SPO2 and LLS exhibited a weak to moderate negative correlation for all days of the study (ρ ranging from -0.142 to -0.370). Calculation of time-shifted associations of 24 and 48 h resulted in the disappearance of most associations. Susceptibility to headaches (odds ratio (OR) 2.9-7.2) and a history of AMS (OR 2.2-3.1) were determined to be potential risk factors for the development of AMS. Since there is no strong altitude-independent association between AMS and SPO2 during the first week of high-altitude adaptation, the implementation of pulse oximetry during trekking in order to detect and predict AMS remains questionable.

Monitoring oxygen levels in orthotopic human glioma xenograft following carbogen inhalation and chemotherapy by implantable resonator-based oximetry.

PubMed

Hou, Huagang; Krishnamurthy Nemani, Venkata; Du, Gaixin; Montano, Ryan; Song, Rui; Gimi, Barjor; Swartz, Harold M; Eastman, Alan; Khan, Nadeem

2015-04-01

Hypoxia is a critical hallmark of glioma, and significantly compromises treatment efficacy. Unfortunately, techniques for monitoring glioma pO2 to facilitate translational research are lacking. Furthermore, poor prognosis of patients with malignant glioma, in particular glioblastoma multiforme, warrant effective strategies that can inhibit hypoxia and improve treatment outcome. EPR oximetry using implantable resonators was implemented for monitoring pO2 in normal cerebral tissue and U251 glioma in mice. Breathing carbogen (95% O2 + 5% CO2 ) was tested for hyperoxia in the normal brain and glioma xenografts. A new strategy to inhibit glioma growth by rationally combining gemcitabine and MK-8776, a cell cycle checkpoint inhibitor, was also investigated. The mean pO2 of left and right hemisphere were ∼56-69 mmHg in the normal cerebral tissue of mice. The mean baseline pO2 of U251 glioma on the first and fifth day of measurement was 21.9 ± 3.7 and 14.1 ± 2.4 mmHg, respectively. The mean brain pO2 including glioma increased by at least 100% on carbogen inhalation, although the response varied between the animals over days. Treatment with gemcitabine + MK-8776 significantly increased pO2 and inhibited glioma growth assessed by MRI. In conclusion, EPR oximetry with implantable resonators can be used to monitor the efficacy of carbogen inhalation and chemotherapy on orthotopic glioma in mice. The increase in glioma pO2 of mice breathing carbogen can be used to improve treatment outcome. The treatment with gemcitabine + MK-8776 is a promising strategy that warrants further investigation. © 2014 UICC.

The Impact of Averaging Window Length on the “Desaturation” Indexes Obtained Via Overnight Pulse Oximetry at High Altitude

PubMed Central

Cross, Troy J.; Keller-Ross, Manda; Issa, Amine; Wentz, Robert; Taylor, Bryan; Johnson, Bruce

2015-01-01

Study Objectives: To determine the impact of averaging window-length on the “desaturation” indexes (DIs) obtained via overnight pulse oximetry (SpO2) at high altitude. Design: Overnight SpO2 data were collected during a 10-day sojourn at high altitude. SpO2 was obtained using a commercial wrist-worn finger oximeter whose firmware was modified to store unaveraged beat-to-beat data. Simple moving averages of window lengths spanning 2 to 20 cardiac beats were retrospectively applied to beat-to-beat SpO2 datasets. After SpO2 artifacts were removed, the following DIs were then calculated for each of the averaged datasets: oxygen desaturation index (ODI); total sleep time with SpO2 < 80% (TST < 80), and the lowest SpO2 observed during sleep (SpO2 low). Setting: South Base Camp, Mt. Everest (5,364 m elevation). Participants: Five healthy, adult males (35 ± 5 y; 180 ± 1 cm; 85 ± 4 kg). Interventions: N/A. Measurements and Results: 49 datasets were obtained from the 5 participants, totalling 239 hours of data. For all window lengths ≥ 2 beats, ODI and TST < 80 were lower, and SpO2 low was higher than those values obtained from the beat-to-beat SpO2 time series data (P < 0.05). Conclusions: Our findings indicate that increasing oximeter averaging window length progressively underestimates the frequency and magnitude of sleep disordered breathing events at high altitude, as indirectly assessed via the desaturation indexes. Citation: Cross TJ, Keller-Ross M, Issa A, Wentz R, Taylor B, Johnson B. The impact of averaging window length on the “desaturation” indexes obtained via overnight pulse oximetry at high altitude. SLEEP 2015;38(8):1331–1334. PMID:25581919

Hyperspectral imaging with near-infrared-enabled mobile phones for tissue oximetry

NASA Astrophysics Data System (ADS)

Lin, Jonathan L.; Ghassemi, Pejhman; Chen, Yu; Pfefer, Joshua

2018-02-01

Hyperspectral reflectance imaging (HRI) is an emerging clinical tool for characterizing spatial and temporal variations in blood perfusion and oxygenation for applications such as burn assessment, wound healing, retinal exams and intraoperative tissue viability assessment. Since clinical HRI-based oximeters often use near-infrared (NIR) light, NIR-enabled mobile phones may provide a useful platform for future point-of-care devices. Furthermore, quantitative NIR imaging on mobile phones may dramatically increase the availability and accessibility of medical diagnostics for low-resource settings. We have evaluated the potential for phone-based NIR oximetry imaging and elucidated factors affecting performance using devices from two different manufacturers, as well as a scientific CCD. A broadband light source and liquid crystal tunable filter were used for imaging at 10 nm bands from 650 to 1000 nm. Spectral sensitivity measurements indicated that mobile phones with standard NIR blocking filters had minimal response beyond 700 nm, whereas one modified phone showed sensitivity to 800 nm and another to 1000 nm. Red pixel channels showed the greatest sensitivity up to 800 nm, whereas all channels provided essentially equivalent sensitivity at longer wavelengths. Referencing of blood oxygenation levels was performed with a CO-oximeter. HRI measurements were performed using cuvettes filled with hemoglobin solutions of different oxygen saturation levels. Good agreement between absorbance spectra measured with mobile phone and a CCD cameras were seen for wavelengths below 900 nm. Saturation estimates showed root-mean-squared-errors of 5.2% and 4.5% for the CCD and phone, respectively. Overall, this work provides strong evidence of the potential for mobile phones to provide quantitative spectral imaging in the NIR for applications such as oximetry, and generates practical insights into factors that impact performance as well as test methods for performance assessment.

Elevated Carboxyhaemoglobin Concentrations by Pulse CO-Oximetry is Associated with Severe Aluminium Phosphide Poisoning.

PubMed

Mashayekhian, Mohammad; Hassanian-Moghaddam, Hossein; Rahimi, Mitra; Zamani, Nasim; Aghabiklooei, Abbas; Shadnia, Shahin

2016-09-01

In pulse CO-oximetry of aluminium phosphide (ALP)-poisoned patients, we discovered that carboxyhaemoglobin (CO-Hb) level was elevated. We aimed to determine whether a higher CO level was detected in patients with severe ALP poisoning and if this could be used as a prognostic factor in these patients. In a prospective case-control study, 96 suspected cases of ALP poisoning were evaluated. In the ALP-poisoned group, demographic characteristics, gastric and exhalation silver nitrate test results, average CO-Hb saturation, methaemoglobin saturation, and blood pressure and blood gas analysis until death/discharge were recorded. Severely poisoned patients were defined as those with systolic blood pressure ≤80 mmHg, pH ≤7.2, or HCO3 ≤15 meq/L or those who died, while patients with minor poisoning were those without any of these signs/symptoms. A control group (37 patients) was taken from other medically ill patients to detect probable effects of hypotension and metabolic acidosis on CO-Hb and methaemoglobin saturations. Of 96 patients, 27 died and 37 fulfilled the criteria for severe poisoning. All patients with carbon monoxide saturation >18% met the criteria to be included in the severe poisoning group and all with a SpCO >25% died. Concerning all significant variables in univariate analysis of severe ALP toxicity, the only significant variable which could independently predict death was carbon monoxide saturation. Due to high mortality rate and need for intensive care support, early prediction of outcome is vital for choosing an appropriate setting (ICU or ordinary ward). CO-oximetry is a good diagnostic and prognostic factor in patients with ALP poisoning even before any clinical evidence of toxicity will develop. © 2016 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

Nocturnal oxygen saturation profiles of healthy term infants

PubMed Central

Terrill, Philip Ian; Dakin, Carolyn; Hughes, Ian; Yuill, Maggie; Parsley, Chloe

2015-01-01

Objective Pulse oximetry is used extensively in hospital and home settings to measure arterial oxygen saturation (SpO2). Interpretation of the trend and range of SpO2 values observed in infants is currently limited by a lack of reference ranges using current devices, and may be augmented by development of cumulative frequency (CF) reference-curves. This study aims to provide reference oxygen saturation values from a prospective longitudinal cohort of healthy infants. Design Prospective longitudinal cohort study. Setting Sleep-laboratory. Patients 34 healthy term infants were enrolled, and studied at 2 weeks, 3, 6, 12 and 24 months of age (N=30, 25, 27, 26, 20, respectively). Interventions Full overnight polysomnography, including 2 s averaging pulse oximetry (Masimo Radical). Main outcome measurements Summary SpO2 statistics (mean, median, 5th and 10th percentiles) and SpO2 CF plots were calculated for each recording. CF reference-curves were then generated for each study age. Analyses were repeated with sleep-state stratifications and inclusion of manual artefact removal. Results Median nocturnal SpO2 values ranged between 98% and 99% over the first 2 years of life and the CF reference-curves shift right by 1% between 2 weeks and 3 months. CF reference-curves did not change with manual artefact removal during sleep and did not vary between rapid eye movement (REM) and non-REM sleep. Manual artefact removal did significantly change summary statistics and CF reference-curves during wake. Conclusions SpO2 CF curves provide an intuitive visual tool for evaluating whether an individual's nocturnal SpO2 distribution falls within the range of healthy age-matched infants, thereby complementing summary statistics in the interpretation of extended oximetry recordings in infants. PMID:25063836

Wearable Oximetry for Harsh Environments

DTIC Science & Technology

characterize the types and significance of motion artifacts that will need to be mitigated. The forehead was confirmed to be an excellent site with...respect to signal quality, but signal corruption from changes in contact pressure will need to be mitigated. The sternal locations are initially assessed

Structuring Expert-leaded Medical Protocols for Tele-Medicine Systems

DTIC Science & Technology

2001-10-25

welfare and health statistics 1991”. Hellenic Republic National Statistical service of Greece, Athens 1994. [3] “ Incentive spirometry pulse...oximetry. O2 therapy in the acute care hospital; spirometry and postural drainage therapy”. Respiratory care 36: 1402-1426, 1991. [4] Economou G.-P

Transcranial oximetry as a new monitoring method for HEMS (Helicopter EMS).

PubMed

Burillo-Putze, Guillermo; Herranz, Ignacio; Pérez, Vicente; Redondo, Faustino; Fernández, Francisco; Jiménez-Sosa, Alejandro; Alvarez, Jesús

2002-01-01

Transcranial oximetry (TCO) is a new method to measure continuous changes in brain blood oxygen saturation (rSO2) by using near-infrared spectroscopy (NIRS). To our knowledge, no studies about TCO in air medical transport have been published. Twenty healthy volunteers (HEMS medical crew) were investigated during flight missions without patients. We measured oxygen saturation (SpO2), cardiac rate, and rSO2 with an INVOS 4100 Cerebral Oximeter at sea level and at each 1000 feet until we reached a flight level of 5000 feet. The oximeter did not produce any interference with medical or aeronautical equipment. Subjects' SpO2 showed a slight decrease with altitude (P < 0.010), but rSO2 remained constant (P = 0.28), with little delay in the physiological correction of SpO2 and rSO2 values. TCO may play an important role in the development of new monitoring methods for critical patients in air medical transport. Further studies with large sample sizes and patients are necessary to generalize findings.

In-vitro model for evaluation of pulse oximetry

NASA Astrophysics Data System (ADS)

Vegfors, Magnus; Lindberg, Lars-Goeran; Lennmarken, Claes; Oberg, P. Ake

1991-06-01

An in vitro model with blood circulating in a silicon tubing system and including an artificial arterial bed is an important tool for evaluation of the pulse oximetry technique. The oxygen saturation was measured on an artificial finger using a pulse oximeter (SpO2) and on blood samples using a hemoximeter (SaO2). Measurements were performed at different blood flows and at different blood hematocrits. An increase in steady as well as in pulsatile blood flow was followed by an increase in pulse oximeter readings and a better agreement between SpO2 and SaO2 readings. After diluting the blood with normal saline (decreased hematocrit) the agreement was further improved. These results indicate that the pulse oximeter signal is related to blood hematocrit and the velocity of blood. The flow-related dependance of SpO2 was also evaluated in a human model. These results provided evidence that the pulse oximeter signal is dependent on vascular changes.

Development of an oximeter for neurology

NASA Astrophysics Data System (ADS)

Aleinik, A.; Serikbekova, Z.; Zhukova, N.; Zhukova, I.; Nikitina, M.

2016-06-01

Cerebral desaturation can occur during surgery manipulation, whereas other parameters vary insignificantly. Prolonged intervals of cerebral anoxia can cause serious damage to the nervous system. Commonly used method for measurement of cerebral blood flow uses invasive catheters. Other techniques include single photon emission computed tomography (SPECT), positron emission tomography (PET), magnetic resonance imaging (MRI). Tomographic methods frequently use isotope administration, that may result in anaphylactic reactions to contrast media and associated nerve diseases. Moreover, the high cost and the need for continuous monitoring make it difficult to apply these techniques in clinical practice. Cerebral oximetry is a method for measuring oxygen saturation using infrared spectrometry. Moreover reflection pulse oximetry can detect sudden changes in sympathetic tone. For this purpose the reflectance pulse oximeter for use in neurology is developed. Reflectance oximeter has a definite advantage as it can be used to measure oxygen saturation in any part of the body. Preliminary results indicate that the device has a good resolution and high reliability. Modern applied schematics have improved device characteristics compared with existing ones.

Photonic textiles for pulse oximetry.

PubMed

Rothmaier, Markus; Selm, Bärbel; Spichtig, Sonja; Haensse, Daniel; Wolf, Martin

2008-08-18

Biomedical sensors, integrated into textiles would enable monitoring of many vitally important physiological parameters during our daily life. In this paper we demonstrate the design and performance of a textile based pulse oximeter, operating on the forefinger tip in transmission mode. The sensors consisted of plastic optical fibers integrated into common fabrics. To emit light to the human tissue and to collect transmitted light the fibers were either integrated into a textile substrate by embroidery (producing microbends with a nominal diameter of 0.5 to 2 mm) or the fibers inside woven patterns have been altered mechanically after fabric production. In our experiments we used a two-wavelength approach (690 and 830 nm) for pulse wave acquisition and arterial oxygen saturation calculation. We have fabricated different specimens to study signal yield and quality, and a cotton glove, equipped with textile based light emitter and detector, has been used to examine movement artifacts. Our results show that textile-based oximetry is feasible with sufficient data quality and its potential as a wearable health monitoring device is promising.

In vivo triarylmethyl radical stabilization through encapsulation in Pluronic F-127 hydrogel

NASA Astrophysics Data System (ADS)

Abbas, Kahina; Boutier-Pischon, Audrey; Auger, Florian; Françon, Dominique; Almario, Antonio; Frapart, Yves-Michel

2016-09-01

In vivo electron paramagnetic resonance (EPR) imaging and spectroscopy are non-invasive technologies used to specifically detect and quantify paramagnetic species. However, the relative instability of spin probes such as triarylmethyl radicals limits their application to conduct oxygen quantification and mapping. In this study we encapsulated tetrathiatriarylmethyl radical (TAM; known as "Finland" probe) in Pluronic F-127 hydrogel (PF-127) in order to limit its degradation and evaluate its in vitro and in vivo EPR properties as a function of oxygen. Our results show that the EPR signal of encapsulated TAM in PF-127 hydrogel is similar to the one in solution. Although it is less sensitive to oxygen, it is suitable for oximetry. We also demonstrated that the incorporation of TAM in PF-127 hydrogel leads to an improved in vivo EPR stability of the radical under anesthesia. This new formulation enables high quality EPR imaging and oximetry and paves the way for the application of TAM radical-based probes in various biomedical fields.

Comparison of infant heart rate assessment by auscultation, ECG and oximetry in the delivery room.

PubMed

Murphy, Madeleine C; De Angelis, Laura; McCarthy, Lisa K; O'Donnell, Colm Patrick Finbarr

2018-05-25

Clinical assessment of an infant's heart rate (HR) in the delivery room (DR) has been reported to be inaccurate. We compared auscultation of the HR using a stethoscope with electrocardiography (ECG) and pulse oximetry (PO) for determining the HR in 92 low-risk newborn infants in the DR. Caregivers auscultated the HR while masked to the HR on the monitor. Auscultation underestimated ECG HR (mean difference (95% CI) by -9 (-15 to -2) beats per minute (bpm)) and PO HR (mean difference (95% CI) by -5 (-12 to 2) bpm). The median (IQR) time to HR by auscultation was 14 (10-18) s. As HR was determined quickly and with reasonable accuracy by auscultation in low-risk newborns, study in high-risk infants is warranted. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Carboxyhemoglobin: a primer for clinicians.

PubMed

Hampson, Neil B

2018-01-01

One of carbon monoxide's several mechanisms of toxicity is binding with circulating hemoglobin to form carboxyhemoglobin, resulting in a functional anemia. While patients with carbon monoxide poisoning are often said to be "cherry-red," such discoloration is rarely seen. Carboxyhemoglobin levels cannot be measured with conventional pulse oximetry, can be approximated with pulse CO-oximetry, and are most accurately measured with a laboratory CO-oximeter. Carboxyhemoglobin levels are quite stable and can be accurately measured on a transported blood sample. For clinical purposes, arterial and venous carboxyhemoglobin levels can be considered to be equivalent. Carboxyhemoglobin levels are typically lower than 2% in non-smokers and lower than 5% in smokers. A level over 9% is almost always due to exogenous carbon monoxide exposure, even among smokers. Conversely, a low level does not exclude significant exposure under certain circumstances. As carboxyhemoglobin levels of poisoned patients do not correlate with symptoms or outcome, their greatest utility is a marker of exposure. Copyright© Undersea and Hyperbaric Medical Society.

Monitoring the Relationship Between Changes in Cerebral Oxygenation and Electroencephalography Patterns During Cardiopulmonary Resuscitation: A Feasibility Study.

PubMed

Reagan, Elizabeth M; Nguyen, Robert T; Ravishankar, Shreyas T; Chabra, Vikram; Fuentes, Barbara; Spiegel, Rebecca; Parnia, Sam

2018-05-01

To date, no studies have examined real-time electroencephalography and cerebral oximetry monitoring during cardiopulmonary resuscitation as markers of the magnitude of global ischemia. We therefore sought to assess the feasibility of combining cerebral oximetry and electroencephalography in patients undergoing cardiopulmonary resuscitation and further to evaluate the electroencephalography patterns during cardiopulmonary resuscitation and their relationship with cerebral oxygenation as measured by cerebral oximetry. Extended case series of in-hospital and out-of-hospital cardiac arrest subjects. Tertiary Medical Center. Inclusion criteria: Convenience sample of 16 patients undergoing cardiopulmonary resuscitation during working hours between March 2014 and March 2015, greater than or equal to 18 years. A portable electroencephalography (Legacy; SedLine, Masimo, Irvine, CA) and cerebral oximetry (Equanox 7600; Nonin Medical, Plymouth, MN) system was used to measure cerebral resuscitation quality. Real-time regional cerebral oxygen saturation and electroencephalography readings were observed during cardiopulmonary resuscitation. The regional cerebral oxygen saturation values and electroencephalography patterns were not used to manage patients by clinical staff. In total, 428 electroencephalography images from 16 subjects were gathered; 40.7% (n = 174/428) were artifactual, therefore 59.3% (n = 254/428) were interpretable. All 16 subjects had interpretable images. Interpretable versus noninterpretable images were not related to a function of time or duration of cardiopulmonary resuscitation but to artifacts that were introduced to the raw data such as diaphoresis, muscle movement, or electrical interference. Interpretable data were able to be obtained immediately after application of the electrode strip. Seven distinct electroencephalography patterns were identified. Voltage suppression was commonest and seen during 78% of overall cardiopulmonary resuscitation time and in 15 of 16 subjects at some point during their cardiopulmonary resuscitation. Other observed patterns and their relative prevalence in relation to overall cardiopulmonary resuscitation time were theta background activity 8%, delta background activity 5%, bi frontotemporal periodic discharge 4%, burst suppression 2%, spike and wave 2%, and rhythmic delta activity 1%. Eight of 16 subjects had greater than one interpretable pattern. At regional cerebral oxygen saturation levels less than or equal to 19%, the observed electroencephalography pattern was exclusively voltage suppression. Delta background activity was only observed at regional cerebral oxygen saturation levels greater than 40%. The remaining patterns were observed throughout regional cerebral oxygen saturation categories above a threshold of 20%. Real-time monitoring of cerebral oxygenation and function during cardiac arrest resuscitation is feasible. Although voltage suppression is the commonest electroencephalography pattern, other distinct patterns exist that may correlate with the quality of cerebral resuscitation and oxygen delivery.

The accuracy of noninvasive hemoglobin measurement by multiwavelength pulse oximetry after cardiac surgery.

PubMed

Nguyen, Ba-Vinh; Vincent, Jean-Louis; Nowak, Emmanuel; Coat, Michelle; Paleiron, Nicolas; Gouny, Pierre; Ould-Ahmed, Mehdi; Guillouet, Maité; Arvieux, Charles Christian; Gueret, Gildas

2011-11-01

In March 2008, a new multiwavelength pulse oximeter, the Radical 7 (Rad7; Masimo Corp., Irvine, CA), was developed that offers noninvasive measurement of hemoglobin concentration. Accuracy has been established in healthy adults and some surgical patients, but not in cardiac surgery intensive care patients, a group at high risk of postoperative bleeding events and anemia in whom early diagnosis could improve management. In this prospective, observational study conducted in a cardiovascular intensive care unit, we compared hemoglobin concentrations shown by the Rad7 with arterial hemoglobin concentrations determined by an automated hematology analyzer, XE-2100 (Roche, Neuilly sur Seine, France). Two software versions of Rad7 (V 7.3.0.1 [42 points of comparison in 14 patients] and the updated V 7.3.1.1 [61 points of comparison in 27 patients]) were studied during two 1-week periods. Bias, defined as the difference between the 2 methods (Masimo SpHb-XE-2100 laboratory hemoglobin), was calculated. A negative bias indicated that the Masimo underestimated hemoglobin compared with the laboratory analyzer. Correlation between the perfusion index given by Rad7 and the hemoglobin bias was also studied. Correlations between Rad7 and XE-2100 were weak for both software versions (R2=0.11 for V 7.3.0.1 and R2=0.27 for V 7.3.1.1). Mean bias was -1.3 g/dL for V 7.3.0.1 and -1.7 g/dL for V 7.3.1.1, with wide 95% prediction intervals for the bias (respectively, -4.6 to 2.1 g/dL and -5.7 to 2.3 g/dL). The absolute hemoglobin bias tended to increase when the perfusion index decreased. For the V 7.3.0.1 software, the average absolute bias was 1.9 g/dL for perfusion index<2 and 0.8 g/dL for perfusion index>2 (P=0.03). For V 7.3.1.1, the mean absolute bias was 2.1 g/dL when the perfusion index was <2, and 1.6 g/dL when the perfusion index was >2 (P=0.26). Our study demonstrates poor correlation between hemoglobin measured noninvasively by multiwavelength pulse oximetry and a laboratory hematology analyzer. The difference was greater when the pulse oximetry perfusion index was low, as may occur in shock, hypothermia, or vasoconstriction patients. The multiwavelength pulse oximetry is not sufficiently accurate for clinical use in a cardiovascular intensive care unit.

Nasal continuous positive airway pressure: does bubbling improve gas exchange?

PubMed

Morley, C J; Lau, R; De Paoli, A; Davis, P G

2005-07-01

In a randomised crossover trial, 26 babies, treated with Hudson prong continuous positive airway pressure (CPAP) from a bubbling bottle, received vigorous, high amplitude, or slow bubbling for 30 minutes. Pulse oximetry, transcutaneous carbon dioxide, and respiratory rate were recorded. The bubbling rates had no effect on carbon dioxide, oxygenation, or respiratory rate.

Vatuximab(Trademark): Optimizing Therapeutic Strategies for Prostate Cancer Based on Dynamic MR Tumor Oximetry

DTIC Science & Technology

2007-01-01

diverse subcutaneous models will be translated to human tumor xenografts in intraosseous models of advanced metastatic prostate cancer (18). Here, PSA...representative MAT-LU, HI and H tumors growing on anesthetized rats breathing air with isoflurane anesthesia . Voxel dimension 1.25 mm in plane with 10

Optimal Fluid Use of Hypotensive Resuscitation and Transport

DTIC Science & Technology

2017-05-01

study in an effort to maintain consistency between animals and to avoid hypoxia during intermittent periods where pulse oximetry readings were lost...or FWB. They were maintained at a target mean arterial pressure (MAP) for 4 hours, holding or infusing fluid as necessary. Sham animals for...2 3.1 Animal Housing and Preparation

Educating the Educator: Use of Pulse Oximetry in Athletic Training

ERIC Educational Resources Information Center

Berry, David C.; Seitz, S. Robert

2012-01-01

The 5th edition of the "Athletic Training Education Competencies" expanded the scope of knowledge and skill set of entry-level athletic trainers related to the domain of "Acute Care of Injuries and Illnesses." One of these major changes includes the introduction of adjunct airway techniques, such as oropharyngeal and nasopharyngeal airways and…

A Single-Chip CMOS Pulse Oximeter with On-Chip Lock-In Detection.

PubMed

He, Diwei; Morgan, Stephen P; Trachanis, Dimitrios; van Hese, Jan; Drogoudis, Dimitris; Fummi, Franco; Stefanni, Francesco; Guarnieri, Valerio; Hayes-Gill, Barrie R

2015-07-14

Pulse oximetry is a noninvasive and continuous method for monitoring the blood oxygen saturation level. This paper presents the design and testing of a single-chip pulse oximeter fabricated in a 0.35 µm CMOS process. The chip includes photodiode, transimpedance amplifier, analogue band-pass filters, analogue-to-digital converters, digital signal processor and LED timing control. The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the transimpedance amplifier, transimpedance gain of the transimpedance amplifier, and the central frequency and bandwidth of the analogue band-pass filters, show a good match (within 1%) with the circuit simulations. With modulated light source and integrated lock-in detection the sensor effectively suppresses the interference from ambient light and 1/f noise. In a breath hold and release experiment the single chip sensor demonstrates consistent and comparable performance to commercial pulse oximetry devices with a mean of 1.2% difference. The single-chip sensor enables a compact and robust design solution that offers a route towards wearable devices for health monitoring.

Preliminary clinical investigations of a new noninvasive venous pulse oximeter

NASA Astrophysics Data System (ADS)

Chan, Daniel; Smith, Peter R.; Caine, Michael P.; Spyt, Tomasz; Boehm, Maria; Machin, David

2003-10-01

For decades, the monitoring of mixed venous oxygen saturation, SvO2 has been performed invasively using fibre-optic catheters. This procedure is not without risk as complications may arise from catheterisation. The group has devised a new non-invasive venous oximetry method which involves inducing regular modulations of the venous blood volume and associated measurement of those modulations using optical means. A clinical investigation was conducted in Glenfield Hospital, UK to evaluate the sensitivity of the new technique to haemodynamic changes such as Cardiac Output (CO) in intraoperative and postoperative cardiac patients. Preliminary trials on patients recovering from cardiac surgery yielded an average correlation of r = 0.72 between CO at different Intra Aortic Balloon Pump (IABP) augmentation levels and SvO2 measured by the new venous oximeter. In intraoperative patients undergoing off-pump cardiac surgery, SvO2 recorded by the new technique responded to unplanned events such as a cardiac arrest. CONCLUSION: The new venous oximetry technique is a promising technique which responds to haemodynamic changes such as CO and with further development might offer an alternative means of monitoring SvO2 non-invasively.

Do changes in pulse oximeter oxygen saturation predict equivalent changes in arterial oxygen saturation?

PubMed

Perkins, Gavin D; McAuley, Daniel F; Giles, Simon; Routledge, Helen; Gao, Fang

2003-08-01

This study investigates the relation between changes in pulse oximeter oxygen saturation (SpO2) and changes in arterial oxygen saturation (SaO2) in the critically ill, and the effects of acidosis and anaemia on precision of using pulse oximetry to predict SaO2. Forty-one consecutive patients were recruited from a nine-bed general intensive care unit into a 2-month study. Patients with significant jaundice (bilirubin >40 micromol/l) or inadequate pulse oximetry tracing were excluded. A total of 1085 paired readings demonstrated only moderate correlation (r= 0.606; P < 0.01) between changes in SpO2 and those in SaO2, and the pulse oximeter tended to overestimate actual changes in SaO2. Anaemia increased the degree of positive bias whereas acidosis reduced it. However, the magnitude of these changes was small. Changes in SpO2 do not reliably predict equivalent changes in SaO2 in the critically ill. Neither anaemia nor acidosis alters the relation between SpO2 and SaO2 to any clinically important extent.

[Relevance of the detection of complex congenital heart disease by screening with pulse oximetry in apparently healthy newborns in health establishments].

PubMed

Jiménez-Carbajal, María Guadalupe; López Pérez, Didier; Fernández Luna, Claudia Paola

2018-03-13

A review is presented of data published in medical literature related to the screening used for the early detection of complex congenital heart disease in apparently healthy newborns in several cities of the world, including those reported in Mexico. The screening was performed due to the knowledge of the pathophysiology of indirect hypoxia data, observation of differential cyanosis and the consequent difference in the values of pre- and post-ductal pulse oximetry derived from the ductal and/or atrial septal defect dependence of several severe congenital heart diseases. Multicentre research studies have also been carried out on a massive scale, thus justifying the usefulness of the practice for its daily implementation and at international level. Additionally, legislative topics are cited in our country as part of the efforts to establish the mandatory nature of the screening throughout the Mexican Republic. Copyright © 2018 Instituto Nacional de Cardiología Ignacio Chávez. Publicado por Masson Doyma México S.A. All rights reserved.

A Single-Chip CMOS Pulse Oximeter with On-Chip Lock-In Detection

PubMed Central

He, Diwei; Morgan, Stephen P.; Trachanis, Dimitrios; van Hese, Jan; Drogoudis, Dimitris; Fummi, Franco; Stefanni, Francesco; Guarnieri, Valerio; Hayes-Gill, Barrie R.

2015-01-01

Pulse oximetry is a noninvasive and continuous method for monitoring the blood oxygen saturation level. This paper presents the design and testing of a single-chip pulse oximeter fabricated in a 0.35 µm CMOS process. The chip includes photodiode, transimpedance amplifier, analogue band-pass filters, analogue-to-digital converters, digital signal processor and LED timing control. The experimentally measured AC and DC characteristics of individual circuits including the DC output voltage of the transimpedance amplifier, transimpedance gain of the transimpedance amplifier, and the central frequency and bandwidth of the analogue band-pass filters, show a good match (within 1%) with the circuit simulations. With modulated light source and integrated lock-in detection the sensor effectively suppresses the interference from ambient light and 1/f noise. In a breath hold and release experiment the single chip sensor demonstrates consistent and comparable performance to commercial pulse oximetry devices with a mean of 1.2% difference. The single-chip sensor enables a compact and robust design solution that offers a route towards wearable devices for health monitoring. PMID:26184225

Laser Doppler Flowmetry and Transcutaneous Oximetry in Chronic Skin Ulcers: A Comparative Evaluation.

PubMed

Raposio, Edoardo; Bertozzi, Nicolò; Moretti, Rebecca; Grignaffini, Eugenio; Grieco, Michele P

2017-07-01

Laser Doppler Flowmetry (LDF) and transcutaneous oximetry (TcpO2) are established methods for investigating cutaneous perfusion. To date, no study previously performed has compared data obtained from these 2 methodologies in cases of chronic cutaneous ulcers. Laser Doppler Flowmetry and TcpO2 were performed in 25 consecutive outpatients with chronic lower limb ulcers (group A, experimental; 9 women and 16 men; mean age 67 years [range, 52-81 years]) and 25 age- and sex-matched healthy control subjects (group B, control) enrolled for the study. Ulcer aetiologies included 12 peripheral arterial occlusive disease, 9 chronic venous insufficiencies, and 4 pressure ulcers. Data were analyzed with Shapiro-Wilk and Wilcoxon-Mann-Whitney tests. A statistically significant difference (P < .05) was found between LDF values of the 2 groups. No statistically significant differences were found between the 2 groups regarding the TcpO2 measurements. The data confirmed the soundness of LDF while investigating local perfusion in patients with chronic cutaneous ulcers. The same diagnostic accuracy was not obtained by means of TcpO2.

Outpatient Management of Children With World Health Organization Chest Indrawing Pneumonia: Implementation Risks and Proposed Solutions.

PubMed

McCollum, Eric D; Ginsburg, Amy Sarah

2017-10-16

This Viewpoints article details our recommendation for the World Health Organization Integrated Management of Childhood Illness guidelines to consider additional referral or daily monitoring criteria for children with chest indrawing pneumonia in low-resource settings. We review chest indrawing physiology in children and relate this to the risk of adverse pneumonia outcomes. We believe there is sufficient evidence to support referring or daily monitoring of children with chest indrawing pneumonia and signs of severe respiratory distress, oxygen saturation <93% (when not at high altitude), moderate malnutrition, or an unknown human immunodeficiency virus (HIV) status in an HIV-endemic setting. Pulse oximetry screening should be routine and performed at the earliest point in the patient care pathway as possible. If outpatient clinics lack capacity to conduct pulse oximetry, nutritional assessment, or HIV testing, then we recommend considering referral to complete the evaluation. When referral is not possible, careful daily monitoring should be performed. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

Wavelength selection method with standard deviation: application to pulse oximetry.

PubMed

Vazquez-Jaccaud, Camille; Paez, Gonzalo; Strojnik, Marija

2011-07-01

Near-infrared spectroscopy provides useful biological information after the radiation has penetrated through the tissue, within the therapeutic window. One of the significant shortcomings of the current applications of spectroscopic techniques to a live subject is that the subject may be uncooperative and the sample undergoes significant temporal variations, due to his health status that, from radiometric point of view, introduce measurement noise. We describe a novel wavelength selection method for monitoring, based on a standard deviation map, that allows low-noise sensitivity. It may be used with spectral transillumination, transmission, or reflection signals, including those corrupted by noise and unavoidable temporal effects. We apply it to the selection of two wavelengths for the case of pulse oximetry. Using spectroscopic data, we generate a map of standard deviation that we propose as a figure-of-merit in the presence of the noise introduced by the living subject. Even in the presence of diverse sources of noise, we identify four wavelength domains with standard deviation, minimally sensitive to temporal noise, and two wavelengths domains with low sensitivity to temporal noise.

Fabrication and physical evaluation of a polymer-encapsulated paramagnetic probe for biomedical oximetry

PubMed Central

Meenakshisundaram, Guruguhan; Eteshola, Edward; Pandian, Ramasamy P.; Bratasz, Anna; Kuppusamy, Periannan

2009-01-01

Lithium octa-n-butoxynaphthalocyanine (LiNc-BuO) is a promising probe for biological electron paramagnetic resonance (EPR) oximetry and is being developed for clinical use. However, clinical applicability of LiNc-BuO may be hindered by potential limitations associated with biocompatibility, biodegradation, and migration of individual crystals in tissue. To overcome these limitations, we have encapsulated LiNc-BuO crystals in polydimethyl siloxane (PDMS), an oxygen-permeable and bioinert polymer, to fabricate conveniently implantable and retrievable oxygen-sensing chips. Encapsulation was performed by a simple cast-molding process, giving appreciable control over size, shape, thickness and spin density of chips. The in vitro oxygen response of the chip was linear, reproducible, and not significantly different from that of unencapsulated crystals. Cast-molding of the structurally-flexible PDMS enabled the fabrication of chips with tailored spin densities, and ensured non-exposure of embedded LiNc-BuO, mitigating potential biocompatibility/toxicological concerns. Our results establish PDMS-encapsulated LiNc-BuO as a promising candidate for further biological evaluation and potential clinical application. PMID:19291409

Measurements of left-to-right intracardiac shunting in adults: oximetric versus indicator dilution techniques.

PubMed

Hillis, L D; Winniford, M D; Jackson, J A; Firth, B G

1985-01-01

Of the various techniques that are available to assess the presence and magnitude of intracardiac shunting, oximetry and indicator dilution are used most frequently. This study was performed to compare these methods in adult patients with pure left-to-right intracardiac shunting. In 27 patients [12 men, 15 women, aged 32 +/- 12 (mean +/- SD) years], shunt magnitude was assessed in close temporal proximity by both techniques. The oximetric percentage left-to-right shunt averaged 55 +/- 16%, whereas the indocyanine green dye percentage shunt was significantly less (36 +/- 14%, p less than 0.001). The oximetric percentage shunt exceeded the indocyanine green dye percentage shunt in 26 and did so by greater than 20% in 23 patients. Thus, there is a substantial difference in shunt magnitude between the oximetric and the indicator dilution techniques. In infants, indicator dilution yields results that are larger than those obtained with the oximetric method. Conversely, in adults, the indicator dilution technique gives results that are consistently smaller than those obtained with oximetry. As a result, the decision regarding therapy of an intracardiac shunt should be made with this in mind.

Measuring arterial oxygenation in a high altitude field environment: comparing portable pulse oximetry with blood gas analysis.

PubMed

Ross, Elliot M; Matteucci, Michael J; Shepherd, Matthew; Barker, Matthew; Orr, Lance

2013-06-01

High altitude environments present unique medical treatment challenges. Medical providers often use small portable pulse oximetry devices to help guide their clinical decision making. A significant body of high altitude research is based on the use of these devices to monitor hypoxia, yet there is a paucity of evidence that these devices are accurate in these environments. We studied whether these devices perform accurately and reliably under true mountain conditions. Healthy unacclimatized active-duty military volunteers participating in mountain warfare training at 2100 m (6900 feet) above sea level were evaluated with several different pulse oximetry devices while in a cold weather, high altitude field environment and then had arterial blood gases (ABG) drawn using an i-STAT for comparison. The pulse oximeter readings were compared with the gold standard ABG readings. A total of 49 individuals completed the study. There was no statistically significant difference between any of the devices and the gold standard of ABG. The best performing device was the PalmSAT (PS) 8000SM finger probe with a mean difference of 2.17% and SD of 2.56 (95% CI, 1.42% to 2.92%). In decreasing order of performance were the PS 8000AA finger probe (mean ± SD, 2.54% ± 2.68%; 95% CI, 1.76% to 3.32%), the PS 8000Q ear probe (2.47% ± 4.36%; 95% CI, 1.21% to 3.75%), the Nonin Onyx 9500 (3.29% ± 3.12%; 95% CI, 2.39% to 4.20%), and finally the PS 8000R forehead reflectance sensor (5.15% ± 2.97%; 95% CI, 4.28% to 6.01%). Based on the results of this study, results of the newer portable pulse oximeters appear to be closely correlated to that of the ABG measurements when tested in true mountain conditions. Copyright © 2013 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

EPR Oximetry for Investigation of Hyperbaric O2 Pre-treatment for Tumor Radiosensitization.

PubMed

Williams, Benjamin B; Hou, Huagang; Coombs, Rachel; Swartz, Harold M

A number of studies have reported benefits associated with the application of hyperbaric oxygen treatment (HBO) delivered immediately prior to radiation therapy. While these studies provide evidence that pre-treatment with HBO may be beneficial, no measurements of intratumoral pO2 were carried out and they do not directly link the apparent benefits to decreased hypoxic fractions at the time of radiation therapy. While there is empirical evidence and some theoretical basis for HBO to enhance radiation therapy, without direct and repeated measurements of its effects on pO2, it is unlikely that the use of HBO can be understood and optimized for clinical applications. In vivo EPR oximetry is a technique uniquely capable of providing repeated direct measurements of pO2 through a non-invasive procedure in both animal models and human patients. In order to evaluate the ability of pretreatment with HBO to elevate tumor pO2, a novel small animal hyperbaric chamber system was constructed that allows simultaneous in vivo EPR oximetry. This chamber can be placed within the EPR magnet and is equipped with a variety of ports for multiplace gas delivery, thermoregulation, delivery of anesthesia, physiologic monitoring, and EPR detection. Initial measurements were performed in a subcutaneous RIF-1 tumor model in C3H/HeJ mice. The mean baseline pO2 value was 6.0 ± 1.2 mmHg (N = 7) and responses to two atmospheres absolute pressure HBO varied considerably across subjects, within tumors, and over time. When an increase in pO2 was observed, the effect was transient in all but one case, with durations lasting from 5 min to over 20 min, and returned to baseline levels during HBO administration. These results indicate that without direct measurements of pO2 in the tissue of interest, it is likely to be difficult to know the effects of HBO on actual tissue pO2.

Using Supervised Machine Learning to Classify Real Alerts and Artifact in Online Multisignal Vital Sign Monitoring Data.

PubMed

Chen, Lujie; Dubrawski, Artur; Wang, Donghan; Fiterau, Madalina; Guillame-Bert, Mathieu; Bose, Eliezer; Kaynar, Ata M; Wallace, David J; Guttendorf, Jane; Clermont, Gilles; Pinsky, Michael R; Hravnak, Marilyn

2016-07-01

The use of machine-learning algorithms to classify alerts as real or artifacts in online noninvasive vital sign data streams to reduce alarm fatigue and missed true instability. Observational cohort study. Twenty-four-bed trauma step-down unit. Two thousand one hundred fifty-three patients. Noninvasive vital sign monitoring data (heart rate, respiratory rate, peripheral oximetry) recorded on all admissions at 1/20 Hz, and noninvasive blood pressure less frequently, and partitioned data into training/validation (294 admissions; 22,980 monitoring hours) and test sets (2,057 admissions; 156,177 monitoring hours). Alerts were vital sign deviations beyond stability thresholds. A four-member expert committee annotated a subset of alerts (576 in training/validation set, 397 in test set) as real or artifact selected by active learning, upon which we trained machine-learning algorithms. The best model was evaluated on test set alerts to enact online alert classification over time. The Random Forest model discriminated between real and artifact as the alerts evolved online in the test set with area under the curve performance of 0.79 (95% CI, 0.67-0.93) for peripheral oximetry at the instant the vital sign first crossed threshold and increased to 0.87 (95% CI, 0.71-0.95) at 3 minutes into the alerting period. Blood pressure area under the curve started at 0.77 (95% CI, 0.64-0.95) and increased to 0.87 (95% CI, 0.71-0.98), whereas respiratory rate area under the curve started at 0.85 (95% CI, 0.77-0.95) and increased to 0.97 (95% CI, 0.94-1.00). Heart rate alerts were too few for model development. Machine-learning models can discern clinically relevant peripheral oximetry, blood pressure, and respiratory rate alerts from artifacts in an online monitoring dataset (area under the curve > 0.87).

Optimal filter bandwidth for pulse oximetry

NASA Astrophysics Data System (ADS)

Stuban, Norbert; Niwayama, Masatsugu

2012-10-01

Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

A two centre observational study of simultaneous pulse oximetry and arterial oxygen saturation recordings in intensive care unit patients.

PubMed

Ebmeier, S J; Barker, M; Bacon, M; Beasley, R C; Bellomo, R; Knee Chong, C; Eastwood, G M; Gilchrist, J; Kagaya, H; Pilcher, J; Reddy, S K; Ridgeon, E; Sarma, N; Sprogis, S; Tanaka, A; Tweedie, M; Weatherall, M; Young, P J

2018-05-01

The influence of variables that might affect the accuracy of pulse oximetry (SpO₂) recordings in critically ill patients is not well established. We sought to describe the relationship between paired SpO₂/SaO₂ (oxygen saturation via arterial blood gas analysis) in adult intensive care unit (ICU) patients and to describe the diagnostic performance of SpO₂ in detecting low SaO₂ and PaO₂. A paired SpO₂/SaO₂ measurement was obtained from 404 adults in ICU. Measurements were used to calculate bias, precision, and limits of agreement. Associations between bias and variables including vasopressor and inotrope use, capillary refill time, hand temperature, pulse pressure, body temperature, oximeter model, and skin colour were estimated. There was no overall statistically significant bias in paired SpO₂/SaO₂ measurements; observed limits of agreement were +/-4.4%. However, body temperature, oximeter model, and skin colour, were statistically significantly associated with the degree of bias. SpO₂ <89% had a sensitivity of 3/7 (42.9%; 95% confidence intervals, CI, 9.9% to 81.6%) and a specificity of 344/384 (89.6%; 95% CI 86.1% to 92.5%) for detecting SaO₂ <89%. The absence of statistically significant bias in paired SpO₂/SaO₂ in adult ICU patients provides support for the use of pulse oximetry to titrate oxygen therapy. However, SpO₂ recordings alone should be used cautiously when SaO₂ recordings of 4.4% higher or lower than the observed SpO₂ would be of concern. A range of variables relevant to the critically ill had little or no effect on bias.

A Brief Review of Non-invasive Monitoring of Respiratory Condition for Extubated Patients with or at Risk for Obstructive Sleep Apnea after Surgery

PubMed Central

Zhang, Xuezheng; Kassem, Mahmoud Attia Mohamed; Zhou, Ying; Shabsigh, Muhammad; Wang, Quanguang; Xu, Xuzhong

2017-01-01

Obstructive sleep apnea (OSA) is one of the important risk factors contributing to postoperative airway complications. OSA alters the respiratory physiology and increases the sensitivity of muscle tone of the upper airway after surgery to residual anesthetic medication. In addition, the prevalence of OSA was reported to be much higher among surgical patients than the general population. Therefore, appropriate monitoring to detect early respiratory impairment in postoperative extubated patients with possible OSA is challenging. Based on the comprehensive clinical observation, several equipment have been used for monitoring the respiratory conditions of OSA patients after surgery, including the continuous pulse oximetry, capnography, photoplethysmography (PPG), and respiratory volume monitor (RVM). To date, there has been no consensus on the most suitable device as a recommended standard of care. In this review, we describe the advantages and disadvantages of some possible monitoring strategies under certain clinical conditions. According to the literature, the continuous pulse oximetry, with its high sensitivity, is still the most widely used device. It is also cost-effective and convenient to use but has low specificity and does not reflect ventilation. Capnography is the most widely used device for detection of hypoventilation, but it may not provide reliable data for extubated patients. Even normal capnography cannot exclude the existence of hypoxia. PPG shows the state of both ventilation and oxygenation, but its sensitivity needs further improvement. RVM provides real-time detection of hypoventilation, quantitative precise demonstration of respiratory rate, tidal volume, and MV for extubated patients, but no reflection of oxygenation. Altogether, the sole use of any of these devices is not ideal for monitoring of extubated patients with or at risk for OSA after surgery. However, we expect that the combined use of continuous pulse oximetry and RVM may be promising for these patients due to their complementary function, which need further study. PMID:28337439

Changes in balance and joint position sense during a 12-day high altitude trek: The British Services Dhaulagiri medical research expedition.

PubMed

Clarke, Sarah B; Deighton, Kevin; Newman, Caroline; Nicholson, Gareth; Gallagher, Liam; Boos, Christopher J; Mellor, Adrian; Woods, David R; O'Hara, John P

2018-01-01

Postural control and joint position sense are essential for safely undertaking leisure and professional activities, particularly at high altitude. We tested whether exposure to a 12-day trek with a gradual ascent to high altitude impairs postural control and joint position sense. This was a repeated measures observational study of 12 military service personnel (28±4 years). Postural control (sway velocity measured by a portable force platform) during standing balance, a Sharpened Romberg Test and knee joint position sense were measured, in England (113m elevation) and at 3 research camps (3619m, 4600m and 5140m) on a 12-day high altitude trek in the Dhaulagiri region of Nepal. Pulse oximetry, and Lake Louise scores were also recorded on the morning and evening of each trek day. Data were compared between altitudes and relationships between pulse oximetry, Lake Louise score, and sway velocity were explored. Total sway velocity during standing balance with eyes open (p = 0.003, d = 1.9) and during Sharpened Romberg test with eyes open (p = 0.007, d = 1.6) was significantly greater at altitudes of 3619m and 5140m when compared with sea level. Anterior-posterior sway velocity during standing balance with eyes open was also significantly greater at altitudes of 3619m and 5140m when compared with sea level (p = 0.001, d = 1.9). Knee joint position sense was not altered at higher altitudes. There were no significant correlations between Lake Louise scores, pulse oximetry and postural sway. Despite a gradual ascent profile, exposure to 3619 m was associated with impairments in postural control without impairment in knee joint position sense. Importantly, these impairments did not worsen at higher altitudes of 4600 m or 5140 m. The present findings should be considered during future trekking expeditions when developing training strategies targeted to manage impairments in postural control that occur with increasing altitude.

Day-night fluctuation of pulse oximetry: an exploratory study in pediatric inpatients.

PubMed

Vargas, Mario H; Heyaime-Lalane, Jorge; Pérez-Rodríguez, Liliana; Zúñiga-Vázquez, Guillermo; Furuya, María Elena Y

2008-01-01

Pulse oximetry is a simple and non-invasive procedure widely used nowadays in the clinical practice. However, it is unclear if SpO2 values are constant throughout the 24 hours of the day or have periodic fluctuations. In the present study we evaluated if progressive day-night variations of SpO, values occur in children. Pulse oximetry (Nonin 2500) was carried out approximately every 2 hours during a 24-hours period in pediatric patients hospitalized due to different diseases but without acute or chronic respiratory diseases. Measurements were analyzed through the cosinor method (sinusoidal curve fitting). A total of 131 patients (23 days to 16 years old) were studied. A sinusoidal fitting of the SpO2 values was accomplished in 84.7% of children. According to these curves, maximal SpO2 values occurred in the late afternoon [4:53 PM (3:49-5:32 PM), median (quartile 1-quartile 3)], while minimal values appeared in the first hours of the day [3:06 AM (2:12-4:08 AM)]. This pattern was the same in sleeping or awake children. More than half of these sinusoidal curves had a period near to 24 hours (between 20 and 28 hours). An additional finding was that maximal and minimal SpO2 values diminished with age (approximately 0.15 and approximately 0.13% SpO2 per year, respectively). In children less than six years old 5th percentile of SpO2 values were 93.8% in the late afternoon and 89.8% in the early hours of the day, while corresponding figures for older children were 91.0% and 88.5%, respectively. Our results suggested that, regardless of the sleep influence, in most children the SpO2 follows a progressive fluctuation during a 24-hours cycle, a pattern which is suggestive of a circadian rhythm. A prospective study in healthy children is warranted.

Validation of the WristOx 3100 oximeter for the diagnosis of sleep apnea/hypopnea syndrome.

PubMed

Nigro, Carlos Alberto; Aimaretti, Silvia; Gonzalez, Sergio; Rhodius, Edgardo

2009-05-01

To evaluate the diagnostic accuracy of the Nonin WristOx 3100 and its software (nVision 5.0) in patients with suspicion of sleep apnea/hypopnea syndrome (SAHS). All participants (168) had the oximetry and polysomnography simultaneously. The two recordings were interpreted blindly. The software calculated: adjusted O(2) desaturation index [ADI]-mean number of O(2) desaturation per hour of total recording analyzed time of > or = 2%, 3%, 4%, 5%, and 6% (ADI2, 3, 4, 5, and 6) and AT90-accumulated time at SO(2) < 90%. The ADI2, 3, 4, 5, and 6 and the AT90 cutoff points that better discriminated between subjects with or without SAHS arose from the receiver operating characteristic curve analysis. The sensitivity (S), specificity (E), and positive and negative likelihood ratio (LR+, LR-) for the different thresholds for ADI were calculated. One hundred and fifty-four patients were included (119 men, mean age 51, median apnea/hypopnea index [AHI] 14, median body mass index [BMI] 28.3 kg/m(2)). The best cutoff points of ADI were: SAHS = AHI > or = 5: ADI2 > 19.3 (S 89%, E 94%, LR+ 15.5 LR- 0.11); SAHS =AHI > or = 10: ADI3 > 10.5 (S 88%, E 94%, LR+ 15 LR- 0.12); SAHS = AHI > or = 15: ADI3 > 13.4 (S 88%, E 90%, LR+ 8.9, LR- 0.14). AT90 had the lowest diagnosis accuracy. An ADI2 < or = 12.2 excluded SAHS (AHI > or = 5 and 10; S 100%, LR- 0) and ADI3 > 4.3 (AHI > or = 5 and 10) or 32 (AHI > or = 15) confirmed SAHS (E 100%). A negative oximetry defined as ADI2 < or = 12.2 excluded SAHS defined as AHI > or = 5 or 10 with a sensitivity and negative likelihood ratio of 100% and 0%, respectively. Furthermore, a positive oximetry defined as an ADI3 > 32 (SAHS = AHI > or = 15) had a specificity of 100% to confirm the pathology.

Precision of noninvasive hemoglobin-level measurement by pulse co-oximetry in patients admitted to intensive care units for severe gastrointestinal bleeds.

PubMed

Coquin, Julien; Dewitte, Antoine; Manach, Yannick Le; Caujolle, Marie; Joannes-Boyau, Olivier; Fleureau, Catherine; Janvier, Gérard; Ouattara, Alexandre

2012-09-01

Measurement of total hemoglobin, based on pulse co-oximetry, is a continuous and noninvasive method that has been principally evaluated in healthy volunteers subjected to hemodilution. We tested the hypothesis that its accuracy could adversely affect patients presenting with severe hemorrhage, which is traditionally associated with increased microvascular tone. Observational study. Twelve-bed mixed medico-surgical intensive care unit. Thirty-three patients admitted to our critical care unit for gastrointestinal bleeds were included. A spectrophotometric sensor was positioned on the patient's fingertip and connected to a pulse co-oximeter. During the first 24 hrs following admission, venous hemoglobin level was determined at the laboratory every 8 hrs and was compared with hemoglobin levels displayed on the pulse co-oximeter measurements screen and/or measured from capillary blood using a portable photometer. The primary end point was the percentage of inaccurate measurements, which were defined as >15% difference compared with reference values or their unavailability for any technical reason. Twenty-five (19%) measurements of pulse co-oximeter measurements were unavailable from the screen. Pulse co-oximeter measurements and capillary hemoglobin levels were significantly correlated to venous hemoglobin level. For venous hemoglobin level compared with pulse co-oximeter measurements (n = 105), and for venous hemoglobin level compared with capillary hemoglobin levels (n = 111), the biases were, respectively, 1.0 ± 1.9 g dL and 0.4 ± 1.0 g dL (p < .05). The proportion of inaccurate measurements was significantly higher for pulse co-oximeter measurements (56% vs. 15%, p < .05). Although the use of norepinephrine did not affect concordance parameters, unavailability of measurements was frequently observed (42% vs. 15%, p < .05). Determination of pulse co-oximetry-based hemoglobin in patients presenting with severe gastrointestinal bleeds can be inaccurate, which renders its use to guide transfusion decisions potentially hazardous. The unavailability of measurements, especially during vasopressor infusion, represents another serious limitation for hemorrhagic patients.

Optimal filter bandwidth for pulse oximetry.

PubMed

Stuban, Norbert; Niwayama, Masatsugu

2012-10-01

Pulse oximeters contain one or more signal filtering stages between the photodiode and microcontroller. These filters are responsible for removing the noise while retaining the useful frequency components of the signal, thus improving the signal-to-noise ratio. The corner frequencies of these filters affect not only the noise level, but also the shape of the pulse signal. Narrow filter bandwidth effectively suppresses the noise; however, at the same time, it distorts the useful signal components by decreasing the harmonic content. In this paper, we investigated the influence of the filter bandwidth on the accuracy of pulse oximeters. We used a pulse oximeter tester device to produce stable, repetitive pulse waves with digitally adjustable R ratio and heart rate. We built a pulse oximeter and attached it to the tester device. The pulse oximeter digitized the current of its photodiode directly, without any analog signal conditioning. We varied the corner frequency of the low-pass filter in the pulse oximeter in the range of 0.66-15 Hz by software. For the tester device, the R ratio was set to R = 1.00, and the R ratio deviation measured by the pulse oximeter was monitored as a function of the corner frequency of the low-pass filter. The results revealed that lowering the corner frequency of the low-pass filter did not decrease the accuracy of the oxygen level measurements. The lowest possible value of the corner frequency of the low-pass filter is the fundamental frequency of the pulse signal. We concluded that the harmonics of the pulse signal do not contribute to the accuracy of pulse oximetry. The results achieved by the pulse oximeter tester were verified by human experiments, performed on five healthy subjects. The results of the human measurements confirmed that filtering out the harmonics of the pulse signal does not degrade the accuracy of pulse oximetry.

A graphical method for comparing nocturnal oxygen saturation profiles in individuals and populations: Application to healthy infants and preterm neonates.

PubMed

Terrill, Philip I; Dakin, Carolyn; Edwards, Bradley A; Wilson, Stephen J; MacLean, Joanna E

2018-05-01

Pulse-oximetry (SpO 2 ) allows the identification of important clinical physiology. However, summary statistics such as mean values and desaturation incidence do not capture the complexity of the information contained within continuous recordings. The aim of this study was to develop an objective method to quantify important SpO 2 characteristics; and assess its utility in healthy infant and preterm neonate cohorts. An algorithm was developed to calculate the desaturation incidence, depth, and duration. These variables are presented using three plots: SpO 2 cumulative-frequency relationship; desaturation-depth versus incidence; desaturation-duration versus incidence. This method was applied to two populations who underwent nocturnal pulse-oximetry: (1) thirty-four healthy term infants studied at 2-weeks, 3, 6, 12, and 24-months of age and (2) thirty-seven neonates born <26 weeks and studied at discharge from NICU (37-44 weeks post-conceptual age). The maturation in healthy infants was characterized by reduced desaturation index (27.2/h vs 3.3/h at 2-weeks and 24-months, P < 0.01), and increased percentage of desaturation events ≥6-s in duration (27.8% vs 43.2% at 2-weeks and 3-months, P < 0.01). Compared with term-infants, preterm infants had a greater desaturation incidence (54.8/h vs 27.2/h, P < 0.01), and these desaturations were deeper (52.9% vs 37.6% were ≥6% below baseline, P < 0.01). The incidence of longer desaturations (≥14-s) in preterm infants was correlated with healthcare utilization over the first 24-months (r = 0.63, P < 0.01). This tool allows the objective comparison of extended oximetry recordings between groups and for individuals; and serves as a basis for the development of reference ranges for populations. © 2018 Wiley Periodicals, Inc.

Nocturnal oxygen saturation profiles of healthy term infants.

PubMed

Terrill, Philip Ian; Dakin, Carolyn; Hughes, Ian; Yuill, Maggie; Parsley, Chloe

2015-01-01

Pulse oximetry is used extensively in hospital and home settings to measure arterial oxygen saturation (SpO2). Interpretation of the trend and range of SpO2 values observed in infants is currently limited by a lack of reference ranges using current devices, and may be augmented by development of cumulative frequency (CF) reference-curves. This study aims to provide reference oxygen saturation values from a prospective longitudinal cohort of healthy infants. Prospective longitudinal cohort study. Sleep-laboratory. 34 healthy term infants were enrolled, and studied at 2 weeks, 3, 6, 12 and 24 months of age (N=30, 25, 27, 26, 20, respectively). Full overnight polysomnography, including 2 s averaging pulse oximetry (Masimo Radical). Summary SpO2 statistics (mean, median, 5th and 10th percentiles) and SpO2 CF plots were calculated for each recording. CF reference-curves were then generated for each study age. Analyses were repeated with sleep-state stratifications and inclusion of manual artefact removal. Median nocturnal SpO2 values ranged between 98% and 99% over the first 2 years of life and the CF reference-curves shift right by 1% between 2 weeks and 3 months. CF reference-curves did not change with manual artefact removal during sleep and did not vary between rapid eye movement (REM) and non-REM sleep. Manual artefact removal did significantly change summary statistics and CF reference-curves during wake. SpO2 CF curves provide an intuitive visual tool for evaluating whether an individual's nocturnal SpO2 distribution falls within the range of healthy age-matched infants, thereby complementing summary statistics in the interpretation of extended oximetry recordings in infants. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Accuracy of pulse oximetry in detection of oxygen saturation in patients admitted to the intensive care unit of heart surgery: comparison of finger, toe, forehead and earlobe probes.

PubMed

Seifi, Sohila; Khatony, Alireza; Moradi, Gholamreza; Abdi, Alireza; Najafi, Farid

2018-01-01

Heart surgery patients are more at risk of poor peripheral perfusion, and peripheral capillary oxygen saturation (SpO2) measurement is regular care for continuous analysis of blood oxygen saturation in these patients. With regard to controversial studies on accuracy of the current pulse oximetry probes and lack of data related to patients undergoing heart surgery, the present study was conducted to determine accuracy of pulse oximetry probes of finger, toe, forehead and earlobe in detection of oxygen saturation in patients admitted to intensive care units for coronary artery bypass surgery. In this clinical trial, 67 patients were recruited based on convenience sampling method among those admitted to intensive care units for coronary artery bypass surgery. The SpO2 value was measured using finger, toe, forehead and earlobe probes and then compared with the standard value of arterial oxygen saturation (SaO2). Data were entered into STATA-11 software and analyzed using descriptive, inferential and Bland-Altman statistical analyses. Highest and lowest correlational mean values of SpO2 and SaO2 were related to finger and earlobe probes, respectively. The highest and lowest agreement of SpO2 and SaO2 were related to forehead and earlobe probes. The SpO2 of earlobe probes due to lesser mean difference, more limited confidence level and higher agreement ration with SaO2 resulted by arterial blood gas (ABG) analysis had higher accuracy. Thus, it is suggested to use earlobe probes in patients admitted to the intensive care unit for coronary artery bypass surgery. Registration of this trial protocol has been approved in Iranian Registry of Clinical Trials at 2018-03-19 with reference IRCT20100913004736N22. "Retrospectively registered."

Real-time pulse oximetry artifact annotation on computerized anaesthetic records.

PubMed

Gostt, Richard Karl; Rathbone, Graeme Dennis; Tucker, Adam Paul

2002-01-01

Adoption of computerised anaesthesia record keeping systems has been limited by the concern that they record artifactual data and accurate data indiscriminately. Data resulting from artifacts does not reflect the patient's true condition and presents a problem in later analysis of the record, with associated medico-legal implications. This study developed an algorithm to automatically annotate pulse oximetry artifacts and sought to evaluate the algorithm's accuracy in routine surgical procedures. MacAnaesthetist is a semi-automatic anaesthetic record keeping system developed for the Apple Macintosh computer, which incorporated an algorithm designed to automatically detect pulse oximetry artifacts. The algorithm labeled artifactual oxygen saturation values < 90%. This was done in real-time by analyzing physiological data captured from a Datex AS/3 Anaesthesia Monitor. An observational study was conducted to evaluate the accuracy of the algorithm during routine surgical procedures (n = 20). An anaesthetic record was made by an anaesthetist using the Datex AS/3 record keeper, while a second anaesthetic record was produced in parallel using MacAnaesthetist. A copy of the Datex AS/3 record was kept for later review by a group of anaesthetists (n = 20), who judged oxygen saturation values < 90% to be either genuine or artifact. MacAnaesthetist correctly labeled 12 out of 13 oxygen saturations < 90% (92.3% accuracy). A post-operative review of the Datex AS/3 anaesthetic records (n = 8) by twenty anaesthetists resulted in 127 correct responses out of total of 200 (63.5% accuracy). The remaining Datex AS/3 records (n = 12) were not reviewed, as they did not contain any oxygen saturations <90%. The real-time artifact detection algorithm developed in this study was more accurate than anaesthetists who post-operatively reviewed records produced by an existing computerised anaesthesia record keeping system. Algorithms have the potential to more accurately identify and annotate artifacts on computerised anaesthetic records, assisting clinicians to more correctly interpret abnormal data.

Wearable oximetry for harsh environments

DTIC Science & Technology

2017-02-23

Firefighters, first responders, warfighters, and explorers must often operate in environmental extremes of temperature (hot or cold), humidity...PSMs) for thermal- work strain are maturing. These monitors typically measure heart rate (HR) from an electrocardiogram (ECG), skin temperature , and...add three primary benefits to PSMs: 1) monitoring altitude sickness and acclimatization via SpO2 (peripheral oxygen saturation) [2], 2) detecting

Vatuximab(Trademark): Optimizing Therapeutic Strategies for Prostate Cancer Based on Dynamic MR Tumor Oximetry

DTIC Science & Technology

2010-01-01

159: 621-631, 2003. 37. Bourke, V. A., Zhao, D., Gilio , J., Chang, C.-H., Jiang, L., Hahn, E. W., and Mason, R. P. Correlation of Radiation...Res. 1998; 150: 549–556. 10. Bourke VA, Zhao D, Gilio J, Chang C-H, Jiang L, Hahn EW, Mason RP. Correlation of radiation response with tumor oxygen

DexterNet: An Open Platform for Heterogeneous Body Sensor Networks and Its Applications

DTIC Science & Technology

2008-12-19

motion, ECG PC, PDA 802.15.4 No No ALARM-NET pulse oximetry STARGATE Bluetooth No Yes [19] motion, ECG PDA, PC 802.11 (temperature, light, PIR) DexterNet...motion, ECG PDA 802.15.4 Yes Possible via SPINE EIP, GPS PC (e.g., air pollution sensor) MICAz, SHIMMER uses MICAz sensors and STARGATE to relay the

Do changes in pulse oximeter oxygen saturation predict equivalent changes in arterial oxygen saturation?

PubMed Central

Perkins, Gavin D; McAuley, Daniel F; Giles, Simon; Routledge, Helen; Gao, Fang

2003-01-01

Introduction This study investigates the relation between changes in pulse oximeter oxygen saturation (SpO2) and changes in arterial oxygen saturation (SaO2) in the critically ill, and the effects of acidosis and anaemia on precision of using pulse oximetry to predict SaO2. Patients and methods Forty-one consecutive patients were recruited from a nine-bed general intensive care unit into a 2-month study. Patients with significant jaundice (bilirubin >40 μmol/l) or inadequate pulse oximetry tracing were excluded. Results A total of 1085 paired readings demonstrated only moderate correlation (r= 0.606; P < 0.01) between changes in SpO2 and those in SaO2, and the pulse oximeter tended to overestimate actual changes in SaO2. Anaemia increased the degree of positive bias whereas acidosis reduced it. However, the magnitude of these changes was small. Conclusion Changes in SpO2 do not reliably predict equivalent changes in SaO2 in the critically ill. Neither anaemia nor acidosis alters the relation between SpO2 and SaO2 to any clinically important extent. PMID:12930558

Reference values for pulse oximetry at high altitude

PubMed Central

Gamponia, M; Babaali, H; Yugar, F; Gilman, R

1998-01-01

OBJECTIVE—To determine reference values for oxygen saturation (SaO2) in healthy children younger than 5 years living at high altitude.
DESIGN—One hundred and sixty eight children were examined for SaO2 at 4018 m during well child visits. Physiological state was also noted during the examination.
RESULTS—The mean SaO2 was 87.3% (95% confidence intervals (CI) 86.7%, 87.9%) with a median value of 87.7%. A significant difference was observed in SaO2 between children younger than 1 year compared with older children, although the difference was no longer demonstrable when sleeping children were excluded.
CONCLUSIONS—This study has provided a reference range of SaO2 values for healthy children under 5 years old so that pulse oximetry may be used as an adjunct in diagnosing acute respiratory infections. Younger children were also shown to have a lower mean SaO2 than older children living at high altitude, which suggests physiological adaptation to high altitude over time. In addition, sleep had a lowering effect on SaO2, although the clinical importance of this remains undetermined.

 PMID:9659095

The Relationship Between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen During Surgery

PubMed Central

Dorotta, Ihab L.; Wells, Briana; Juma, David; Applegate, Patricia M.

2016-01-01

BACKGROUND: The use of intraoperative pulse oximetry (Spo2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, Spo2 may be reported as 98% when arterial partial pressure of oxygen (Pao2) is as low as 70 mm Hg. Therefore, Spo2 may not provide advance warning of falling arterial oxygenation until Pao2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when Spo2 is >98%. This study evaluates the ORI to Pao2 relationship during surgery. METHODS: We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with Pao2 obtained from each arterial blood gas measurement and changes in ORI with changes in Pao2 from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured Pao2 and ORI and for the unequal time intervals of Pao2 determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to Pao2 of 100 and 150 mm Hg. ORI and Pao2 were compared using mixed-effects models with a subject-specific random intercept. RESULTS: ORI values and Pao2 measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to Pao2 relationship was stronger for Pao2 to 240 mm Hg (r2 = 0.536) than for Pao2 over 240 mm Hg (r2 = 0.0016). Measured Pao2 was ≥100 mm Hg for all ORI over 0.24. Measured Pao2 was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that Pao2 was significantly related to ORI (β[95% confidence interval] = 0.002 [0.0019–0.0022]; P < 0.0001). A similar analysis indicated a significant relationship between change in Pao2 and change in ORI (β [95% confidence interval] = 0.0044 [0.0040–0.0048]; P < 0.0001). CONCLUSIONS: These findings suggest that ORI >0.24 can distinguish Pao2 ≥100 mm Hg when Spo2 is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish Pao2 ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling Pao2 approaching 100 mm Hg when Spo2 is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively. PMID:27007078

The Relationship Between Oxygen Reserve Index and Arterial Partial Pressure of Oxygen During Surgery.

PubMed

Applegate, Richard L; Dorotta, Ihab L; Wells, Briana; Juma, David; Applegate, Patricia M

2016-09-01

The use of intraoperative pulse oximetry (SpO2) enhances hypoxia detection and is associated with fewer perioperative hypoxic events. However, SpO2 may be reported as 98% when arterial partial pressure of oxygen (PaO2) is as low as 70 mm Hg. Therefore, SpO2 may not provide advance warning of falling arterial oxygenation until PaO2 approaches this level. Multiwave pulse co-oximetry can provide a calculated oxygen reserve index (ORI) that may add to information from pulse oximetry when SpO2 is >98%. This study evaluates the ORI to PaO2 relationship during surgery. We studied patients undergoing scheduled surgery in which arterial catheterization and intraoperative arterial blood gas analysis were planned. Data from multiple pulse co-oximetry sensors on each patient were continuously collected and stored on a research computer. Regression analysis was used to compare ORI with PaO2 obtained from each arterial blood gas measurement and changes in ORI with changes in PaO2 from sequential measurements. Linear mixed-effects regression models for repeated measures were then used to account for within-subject correlation across the repeatedly measured PaO2 and ORI and for the unequal time intervals of PaO2 determination over elapsed surgical time. Regression plots were inspected for ORI values corresponding to PaO2 of 100 and 150 mm Hg. ORI and PaO2 were compared using mixed-effects models with a subject-specific random intercept. ORI values and PaO2 measurements were obtained from intraoperative data collected from 106 patients. Regression analysis showed that the ORI to PaO2 relationship was stronger for PaO2 to 240 mm Hg (r = 0.536) than for PaO2 over 240 mm Hg (r = 0.0016). Measured PaO2 was ≥100 mm Hg for all ORI over 0.24. Measured PaO2 was ≥150 mm Hg in 96.6% of samples when ORI was over 0.55. A random intercept variance component linear mixed-effects model for repeated measures indicated that PaO2 was significantly related to ORI (β[95% confidence interval] = 0.002 [0.0019-0.0022]; P < 0.0001). A similar analysis indicated a significant relationship between change in PaO2 and change in ORI (β [95% confidence interval] = 0.0044 [0.0040-0.0048]; P < 0.0001). These findings suggest that ORI >0.24 can distinguish PaO2 ≥100 mm Hg when SpO2 is over 98%. Similarly, ORI > 0.55 appears to be a threshold to distinguish PaO2 ≥150 mm Hg. The usefulness of these values should be evaluated prospectively. Decreases in ORI to near 0.24 may provide advance indication of falling PaO2 approaching 100 mm Hg when SpO2 is >98%. The clinical utility of interventions based on continuous ORI monitoring should be studied prospectively.

Accuracy of continuous noninvasive hemoglobin monitoring for the prediction of blood transfusions in trauma patients.

PubMed

Galvagno, Samuel M; Hu, Peter; Yang, Shiming; Gao, Cheng; Hanna, David; Shackelford, Stacy; Mackenzie, Colin

2015-12-01

Early detection of hemorrhagic shock is required to facilitate prompt coordination of blood component therapy delivery to the bedside and to expedite performance of lifesaving interventions. Standard physical findings and vital signs are difficult to measure during the acute resuscitation stage, and these measures are often inaccurate until patients deteriorate to a state of decompensated shock. The aim of this study is to examine a severely injured trauma patient population to determine whether a noninvasive SpHb monitor can predict the need for urgent blood transfusion (universal donor or additional urgent blood transfusion) during the first 12 h of trauma patient resuscitation. We hypothesize that trends in continuous SpHb, combined with easily derived patient-specific factors, can identify the immediate need for transfusion in trauma patients. Subjects were enrolled if directly admitted to the trauma center, >17 years of age, and with a shock index (heart rate/systolic blood pressure) >0.62. Upon admission, a Masimo Radical-7 co-oximeter sensor (Masimo Corporation, Irvine, CA) was applied, providing measurement of continuous non-invasive hemoglobin (SpHb) levels. Blood was drawn and hemoglobin concentration analyzed and conventional pulse oximetry photopletysmograph signals were continuously recorded. Demographic information and both prehospital and admission vital signs were collected. The primary outcome was transfusion of at least one unit of packed red blood cells within 24 h of admission. Eight regression models (C1-C8) were evaluated for the prediction of blood use by comparing area under receiver operating curve (AUROC) at different time intervals after admission. 711 subjects had continuous vital signs waveforms available, to include heart rate (HR), SpHb and SpO2 trends. When SpHb was monitored for 15 min, SpHb did not increase AUROC for prediction of transfusion. The highest ROC was recorded for model C8 (age, sex, prehospital shock index, admission HR, SpHb and SpO2) for the prediction of blood products within the first 3 h of admission. When data from 15 min of continuous monitoring were analyzed, significant improvement in AUROC occurred as more variables were added to the model; however, the addition of SpHb to any of the models did not improve AUROC significantly for prediction of blood use within the first 3 h of admission in comparison to analysis of conventional oximetry features. The results demonstrate that SpHb monitoring, accompanied by continuous vital signs data and adjusted for age and sex, has good accuracy for the prediction of need for transfusion; however, as an independent variable, SpHb did not enhance predictive models in comparison to use of features extracted from conventional pulse oximetry. Nor was shock index better than conventional oximetry at discriminating hemorrhaging and prediction of casualties receiving blood. In this population of trauma patients, noninvasive SpHb monitoring, including both trends and absolute values, did not enhance the ability to predict the need for blood transfusion.

Oximetry: A Reflective Tool for the Detection of Physiological Expression of Emotions in a Science Education Classroom

ERIC Educational Resources Information Center

Calderón, Olga

2016-01-01

The pulse oximeter is a device that measures the oxygen concentration (or oxygen saturation--SpO[subscript 2]); heart rate, and heartbeat of a person at any given time. This instrument is commonly used in medical and aerospace fields to monitor physiological outputs of a patient according to health conditions or physiological yields of a flying…

Role of Noninvasive Hemoglobin Monitoring in Trauma

DTIC Science & Technology

2015-03-25

spectrophotometry-based monitoring technology (Radical-7® Pulse CO- Oximeter ; Masimo Corp., Irvine, CA) that provides continuous hemoglobin...116(1):65-72. 14. Masimo Corp. Radical-7 signal extraction pulse co- oximeter operator’s manual. Irvine (CA): Masimo Corp.; 2007. 15. Bland JM...method similar to conventional pulse oximetry. Transmitted light is captured by photodiode receptor and analyzed to create an analog signal that, in

Prevalence, clinical profile, iron status, and subject-specific traits for excessive erythrocytosis in andean adults living permanently at 3,825 meters above sea level.

PubMed

De Ferrari, Aldo; Miranda, J Jaime; Gilman, Robert H; Dávila-Román, Victor G; León-Velarde, Fabiola; Rivera-Ch, Maria; Huicho, Luis; Bernabé-Ortiz, Antonio; Wise, Robert A; Checkley, William

2014-11-01

Excessive erythrocytosis (EE) is a prevalent condition in populations living at high altitudes (> 2,500 m above sea level). Few large population-based studies have explored the association between EE and multiple subject-specific traits including oxygen saturation, iron status indicators, and pulmonary function. We enrolled a sex-stratified and age-stratified sample of 1,065 high-altitude residents aged ≥ 35 years from Puno, Peru (3,825 m above sea level) and conducted a standardized questionnaire and physical examination that included spirometry, pulse oximetry, and a blood sample for multiple clinical markers. Our primary objectives were to estimate the prevalence of EE, characterize the clinical profile and iron status indicators of subjects with EE, and describe subject-specific traits associated with EE. Overall prevalence of EE was 4.5% (95% CI, 3.3%-6.0%). Oxygen saturation was significantly lower among EE than non-EE group subjects (85.3% vs 90.1%, P < .001) but no difference was found in iron status indicators between both groups (P > .09 for all values). In multivariable logistic regression, we found that age ≥ 65 years (OR = 2.45, 95% CI, 1.16-5.09), male sex (3.86, 1.78-9.08), having metabolic syndrome (2.66, 1.27-5.75) or being overweight (5.20, 1.95-16.77), pulse oximetry < 85% (14.90, 6.43-34.90), and % predicted FVC < 80% (13.62, 4.40-41.80) were strongly associated with EE. Attributable fractions for EE were greatest for being overweight (26.7%), followed by male sex (21.5%), pulse oximetry < 85% (16.4%), having metabolic syndrome (14.4%), and % predicted FVC < 80% (9.3%). We found a lower prevalence of EE than in previous reports in the Peruvian Andes. Although the presence of hypoxemia and decreased vital capacity were strongly associated with excessive erythrocytosis, being overweight or having metabolic syndrome were associated with an important fraction of cases in our study population.

Prevalence, Clinical Profile, Iron Status, and Subject-Specific Traits for Excessive Erythrocytosis in Andean Adults Living Permanently at 3,825 Meters Above Sea Level

PubMed Central

De Ferrari, Aldo; Miranda, J. Jaime; Gilman, Robert H.; Dávila-Román, Victor G.; León-Velarde, Fabiola; Rivera-Ch, Maria; Huicho, Luis; Bernabé-Ortiz, Antonio; Wise, Robert A.

2014-01-01

BACKGROUND: Excessive erythrocytosis (EE) is a prevalent condition in populations living at high altitudes (> 2,500 m above sea level). Few large population-based studies have explored the association between EE and multiple subject-specific traits including oxygen saturation, iron status indicators, and pulmonary function. METHODS: We enrolled a sex-stratified and age-stratified sample of 1,065 high-altitude residents aged ≥ 35 years from Puno, Peru (3,825 m above sea level) and conducted a standardized questionnaire and physical examination that included spirometry, pulse oximetry, and a blood sample for multiple clinical markers. Our primary objectives were to estimate the prevalence of EE, characterize the clinical profile and iron status indicators of subjects with EE, and describe subject-specific traits associated with EE. RESULTS: Overall prevalence of EE was 4.5% (95% CI, 3.3%-6.0%). Oxygen saturation was significantly lower among EE than non-EE group subjects (85.3% vs 90.1%, P < .001) but no difference was found in iron status indicators between both groups (P > .09 for all values). In multivariable logistic regression, we found that age ≥ 65 years (OR = 2.45, 95% CI, 1.16-5.09), male sex (3.86, 1.78-9.08), having metabolic syndrome (2.66, 1.27-5.75) or being overweight (5.20, 1.95-16.77), pulse oximetry < 85% (14.90, 6.43-34.90), and % predicted FVC < 80% (13.62, 4.40-41.80) were strongly associated with EE. Attributable fractions for EE were greatest for being overweight (26.7%), followed by male sex (21.5%), pulse oximetry < 85% (16.4%), having metabolic syndrome (14.4%), and % predicted FVC < 80% (9.3%). CONCLUSIONS: We found a lower prevalence of EE than in previous reports in the Peruvian Andes. Although the presence of hypoxemia and decreased vital capacity were strongly associated with excessive erythrocytosis, being overweight or having metabolic syndrome were associated with an important fraction of cases in our study population. PMID:24874587

Acute hypoxia in a simulated high-altitude airdrop scenario due to oxygen system failure.

PubMed

Ottestad, William; Hansen, Tor Are; Pradhan, Gaurav; Stepanek, Jan; Høiseth, Lars Øivind; Kåsin, Jan Ivar

2017-12-01

High-Altitude High Opening (HAHO) is a military operational procedure in which parachute jumps are performed at high altitude requiring supplemental oxygen, putting personnel at risk of acute hypoxia in the event of oxygen equipment failure. This study was initiated by the Norwegian Army to evaluate potential outcomes during failure of oxygen supply, and to explore physiology during acute severe hypobaric hypoxia. A simulated HAHO without supplemental oxygen was carried out in a hypobaric chamber with decompression to 30,000 ft (9,144 m) and then recompression to ground level with a descent rate of 1,000 ft/min (305 m/min). Nine subjects were studied. Repeated arterial blood gas samples were drawn throughout the entire hypoxic exposure. Additionally, pulse oximetry, cerebral oximetry, and hemodynamic variables were monitored. Desaturation evolved rapidly and the arterial oxygen tensions are among the lowest ever reported in volunteers during acute hypoxia. Pa O 2 decreased from baseline 18.4 (17.3-19.1) kPa, 138.0 (133.5-143.3) mmHg, to a minimum value of 3.3 (2.9-3.7) kPa, 24.8 (21.6-27.8) mmHg, after 180 (60-210) s, [median (range)], N = 9. Hyperventilation with ensuing hypocapnia was associated with both increased arterial oxygen saturation and cerebral oximetry values, and potentially improved tolerance to severe hypoxia. One subject had a sharp drop in heart rate and cardiac index and lost consciousness 4 min into the hypoxic exposure. A simulated high-altitude airdrop scenario without supplemental oxygen results in extreme hypoxemia and may result in loss of consciousness in some individuals. NEW & NOTEWORTHY This is the first study to investigate physiology and clinical outcome of oxygen system failure in a simulated HAHO scenario. The acquired knowledge is of great value to make valid risk-benefit analyses during HAHO training or operations. The arterial oxygen tensions reported in this hypobaric chamber study are among the lowest ever reported during acute hypoxia. Copyright © 2017 the American Physiological Society.

Methaemoglobinaemia presenting with status epilepticus.

PubMed Central

Malhotra, R; Hughes, G

1996-01-01

A case is reported of methaemoglobinaemia presenting with recurrent fits in the absence of cyanosis. A low oxygen saturation measured on pulse oximetry that fails to improve with oxygen treatment, the presence of "chocolate brown" blood that does not change on exposure to air, and a high PaO2 arterial blood gas with oxygen therapy should support such a diagnosis. A diagnostic blood methaemoglobin level should be obtained. PMID:9091107

Mobile, Multi-modal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia

DTIC Science & Technology

2016-10-01

Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT Coherent anti-stokes Raman spectroscopy ( CARS ) can be used to detect differences in the oxygen content...oxygen, eye, retina, photoreceptor, neuron, TRPM7, neurodegeneration, neurotoxicity, coherent anti-Stokes Raman spectroscopy, CARS , mouse 16...ANSI Std. Z39.18 Section 1: Introduction The study is based on the premise that Coherent Anti-Stokes Raman scattering ( CARS ) imaging provides a

Overload and neovascularization of shoulder tendons in volleyball players

PubMed Central

2012-01-01

Background In overhead sports like volleyball, the onset of a rotator cuff tendinopathy due to functional overload is a common observation. An angiofibroblastic etiopathogenesis has been hypothesized, whereby a greater anaerobic metabolism occurs in critical zones of the tendon with a lower degree of vascularization; this would induce collagen and extracellular matrix degradation, that could then trigger a compensatory neovascularization response. We performed a clinical observational study of 80 elite volleyball players, monitoring the perfusion values of the supraspinatus tendons by oximetry. Results No statistically significant differences were found between the oximetry data and age, sex or years of sports activity, nor when comparing the right and left arm or the dominant and non-dominant arm. A statistically significant difference was found for the dominant arm values in relation to the competitive role, higher values being obtained in outside hitters (62.7%) than middle hitters (53.7%) (p = 0.01), opposite hitters (55.5%) (p = 0.02) and libero players (54.4%) (p = 0.008), whereas there were no differences in setters (56.2%) (p > 0.05). Conclusions The different tendon vascularization values found in players with different roles in the team may be attributed to a response to the specific biomechanical demands posed by the different overhead throwing roles. PMID:22853746

Siloxane nanoprobes for labeling and dual modality imaging of neural stem cells

PubMed Central

Addington, Caroline P.; Cusick, Alex; Shankar, Rohini Vidya; Agarwal, Shubhangi; Stabenfeldt, Sarah E.; Kodibagkar, Vikram D.

2015-01-01

Cell therapy represents a promising therapeutic for a myriad of medical conditions, including cancer, traumatic brain injury, and cardiovascular disease among others. A thorough understanding of the efficacy and cellular dynamics of these therapies necessitates the ability to non-invasively track cells in vivo. Magnetic resonance imaging (MRI) provides a platform to track cells as a non-invasive modality with superior resolution and soft tissue contrast. We recently reported a new nanoprobe platform for cell labeling and imaging using fluorophore doped siloxane core nanoemulsions as dual modality (1H MRI/Fluorescence), dual-functional (oximetry/detection) nanoprobes. Here, we successfully demonstrate the labeling, dual-modality imaging, and oximetry of neural progenitor/stem cells (NPSCs) in vitro using this platform. Labeling at a concentration of 10 μl/104 cells with a 40%v/v polydimethylsiloxane core nanoemulsion, doped with rhodamine, had minimal effect on viability, no effect on migration, proliferation and differentiation of NPSCs and allowed for unambiguous visualization of labeled NPSCs by 1H MR and fluorescence and local pO2 reporting by labeled NPSCs. This new approach for cell labeling with a positive contrast 1H MR probe has the potential to improve mechanistic knowledge of current therapies, and guide the design of future cell therapies due to its clinical translatability. PMID:26597417

Miniaturized Battery-Free Wireless Systems for Wearable Pulse Oximetry.

PubMed

Kim, Jeonghyun; Gutruf, Philipp; Chiarelli, Antonio M; Heo, Seung Yun; Cho, Kyoungyeon; Xie, Zhaoqian; Banks, Anthony; Han, Seungyoung; Jang, Kyung-In; Lee, Jung Woo; Lee, Kyu-Tae; Feng, Xue; Huang, Yonggang; Fabiani, Monica; Gratton, Gabriele; Paik, Ungyu; Rogers, John A

2017-01-05

Development of unconventional technologies for wireless collection, storage and analysis of quantitative, clinically relevant information on physiological status is of growing interest. Soft, biocompatible systems are widely regarded as important because they facilitate mounting on external (e.g. skin) and internal (e.g. heart, brain) surfaces of the body. Ultra-miniaturized, lightweight and battery-free devices have the potential to establish complementary options in bio-integration, where chronic interfaces (i.e. months) are possible on hard surfaces such as the fingernails and the teeth, with negligible risk for irritation or discomfort. Here we report materials and device concepts for flexible platforms that incorporate advanced optoelectronic functionality for applications in wireless capture and transmission of photoplethysmograms, including quantitative information on blood oxygenation, heart rate and heart rate variability. Specifically, reflectance pulse oximetry in conjunction with near-field communication (NFC) capabilities enables operation in thin, miniaturized flexible devices. Studies of the material aspects associated with the body interface, together with investigations of the radio frequency characteristics, the optoelectronic data acquisition approaches and the analysis methods capture all of the relevant engineering considerations. Demonstrations of operation on various locations of the body and quantitative comparisons to clinical gold standards establish the versatility and the measurement accuracy of these systems, respectively.

The evaluation of new and isotopically labeled isoindoline nitroxides and an azaphenalene nitroxide for EPR oximetry

PubMed Central

Khan, Nadeem; Blinco, James P.; Bottle, Steven E.; Hosokawa, Kazuyuki; Swartz, Harold M.; Micallef, Aaron S.

2011-01-01

Isoindoline nitroxides are potentially useful probes for viable biological systems, exhibiting low cytotoxicity, moderate rates of biological reduction and favorable Electron Paramagnetic Resonance (EPR) characteristics. We have evaluated the anionic (5-carboxy-1,1,3,3-tetramethylisoindolin-2-yloxyl; CTMIO), cationic (5-(N,N,N-trimethylammonio)-1,1,3,3-tetramethylisoindolin-2-yloxyl iodide, QATMIO) and neutral (1,1,3,3-tetramethylisoindolin-2-yloxyl; TMIO) nitroxides and their isotopically labeled analogues (2H12- and/or 2H12-15N-labeled) as potential EPR oximetry probes. An active ester analogue of CTMIO, designed to localize intracellularly, and the azaphenalene nitroxide 1,1,3,3-tetramethyl-2,3-dihydro-2-azaphenalen-2-yloxyl (TMAO) were also studied. While the EPR spectra of the unlabeled nitroxides exhibit high sensitivity to O2 concentration, deuteration resulted in a loss of superhyperfine features and a subsequent reduction in O2 sensitivity. Labeling the nitroxides with 15N increased the signal intensity and this may be useful in decreasing the detection limits for in vivo measurements. The active ester nitroxide showed approximately 6% intracellular localization and low cytotoxicity. The EPR spectra of TMAO nitroxide indicated an increased rigidity in the nitroxide ring, due to dibenzo-annulation. PMID:21665499

What we have learned about intrapartum fetal monitoring trials in the MFMU Network.

PubMed

Bloom, Steven L; Belfort, Michael; Saade, George

2016-08-01

The vast majority of pregnant women are subjected to electronic fetal heart monitoring during labor. There is limited evidence to support its benefit compared with intermittent auscultation. In addition, there is significant variability in interpretation and its false-positive rate is high. The latter may have contributed to the rise in operative deliveries. In order to address the critical need for better approaches to intrapartum monitoring, the MFMU Network has completed two large multisite randomized trials, one to evaluate fetal pulse oximetry and the other to evaluate fetal ECG ST segment analysis (STAN). Both of these technologies had been approved for clinical use in the United States based on prior smaller trials. These technologies were evaluated in laboring women near term and their primary outcomes were overall cesarean delivery for the oximetry trial and a composite adverse neonatal outcome for STAN. Both the trials failed to show a benefit of the technology, neither in the rates of operative deliveries nor in the rates of adverse neonatal outcomes. The experience with these trials, summarized in this report, highlights the need for rigorous evidence before introduction of new technology into clinical practice and provides a blueprint for future trials to address the need for better intrapartum monitoring approaches. Copyright © 2016 Elsevier Inc. All rights reserved.

Examiner's finger-mounted fetal tissue oximetry.

PubMed

Kanayama, Naohiro; Niwayama, Masatsugu

2014-06-01

The best way to assess fetal condition is to observe the oxygen status of the fetus (as well as to assess the condition of infants, children, and adults). Previously, several fetal oximeters have been developed; however, no instrument has been utilized in clinical practice because of the low-capturing rate of the fetal oxygen saturation. To overcome the problem, we developed a doctor's finger-mounted fetal tissue oximeter, whose sensor volume is one hundredth of the conventional one. Additionally, we prepared transparent gloves. The calculation algorithm of the hemoglobin concentration was derived from the light propagation analysis based on the transport theory. We measured neonatal and fetal oxygen saturation (StO₂) with the new tissue oximeter. Neonatal StO₂ was measured at any position of the head regardless of amount of hair. Neonatal StO₂ was found to be around 77%. Fetal StO₂ was detected in every position of the fetal head during labor regardless of the presence of labor pain. Fetal StO₂ without labor pain was around 70% in the first stage of labor and around 60% in the second stage of labor. We concluded that our new concept of fetal tissue oximetry would be useful for detecting fetal StO₂ in any condition of the fetus.

Axial oxygen diffusion in the Krogh model: modifications to account for myocardial oxygen tension in isolated perfused rat hearts measured by EPR oximetry.

PubMed

Grinberg, Oleg; Novozhilov, Boris; Grinberg, Stalina; Friedman, Bruce; Swartz, Harold M

2005-01-01

The cylindrical steady-state model developed by Krogh with Erlang has served as the basis of understanding oxygen supply in living tissue for over eighty years. Due to its simplicity and agreement with some observations, it has been extensively used and successfully extended to new fields, especially for situations such as drug diffusion, water transport, and ice formation in tissues. However, the applicability of the model to make even a qualitative prediction of the oxygen level of specific volumes of the tissue is still controversial. We recently have developed an approximate analytical solution of a steady-state diffusion equation for a Krogh cylinder, including oxygen concentration in the capillary. This model was used to explain our previous experimental data on myocardial pO2 in isolated perfused rat hearts measured by EPR oximetry. An acceptable agreement with the experimental data was obtained by assuming that a known limitation of the existing EPR methods--a tendency to over-weight low pO2 values--had resulted in an under-estimate of the pO2. These results are consistent with recent results of others, which stress the importance of taking into account the details of what is measured by various methods.

Pilot study of oxygen transport rate of banked red blood cells.

PubMed

Buchwald, H; Menchaca, H J; Michalek, V N; Rudser, K D; Rohde, T D; O'Dea, T; Connett, J E; Gorlin, J

2009-01-01

Dynamic oximetry provides a new way to assess the effect of blood storage on the oxygen transport rate (OTR). In dynamic oximetry, the rate at which oxyhemoglobin becomes deoxyhemoglobin is measured optically, thereby, indirectly measuring the rate at which oxygen leaves the red blood cell (RBC) making it available for transfer to tissues. Extending the physiologic diffusion time in an in vitro apparatus, consisting of a diffusion system and gas exchanger capable of controlling the surface area and the time of exposure for oxygenation and deoxygenation, makes OTR measurement feasible. Eight normal blood donor units, collected in adenine, dextrose, sorbitol, sodium chloride and mannitol , were stored for 8 weeks under standard conditions and serially sampled for OTR. We report that the OTR at the time of blood bank donation appears to be singular for each donor, that the interdonor differences are maintained over time, and that the individual OTR increased 1.72-fold (95% CI 1.51, 1.95) over 8 weeks, adjusting for sex, age and plasma cholesterol level. Oxygen transport rate increases during storage; blood units with similar haemoglobin content may have significant differences in OTR. Studies examining blood parameters at the time of donation and blood storage on patient outcomes should consider measuring OTR, as it may contribute to differences in observed efficacy of tissue oxygenation.

Design and evaluation of a low-cost smartphone pulse oximeter.

PubMed

Petersen, Christian L; Chen, Tso P; Ansermino, J Mark; Dumont, Guy A

2013-12-06

Infectious diseases such as pneumonia take the lives of millions of children in low- and middle-income countries every year. Many of these deaths could be prevented with the availability of robust and low-cost diagnostic tools using integrated sensor technology. Pulse oximetry in particular, offers a unique non-invasive and specific test for an increase in the severity of many infectious diseases such as pneumonia. If pulse oximetry could be delivered on widely available mobile phones, it could become a compelling solution to global health challenges. Many lives could be saved if this technology was disseminated effectively in the affected regions of the world to rescue patients from the fatal consequences of these infectious diseases. We describe the implementation of such an oximeter that interfaces a conventional clinical oximeter finger sensor with a smartphone through the headset jack audio interface, and present a simulator-based systematic verification system to be used for automated validation of the sensor interface on different smartphones and media players. An excellent agreement was found between the simulator and the audio oximeter for both oxygen saturation and heart rate over a wide range of optical transmission levels on 4th and 5th generations of the iPod TouchTM and iPhoneTM devices.

Arterial input function of an optical tracer for dynamic contrast enhanced imaging can be determined from pulse oximetry oxygen saturation measurements

NASA Astrophysics Data System (ADS)

Elliott, Jonathan T.; Wright, Eric A.; Tichauer, Kenneth M.; Diop, Mamadou; Morrison, Laura B.; Pogue, Brian W.; Lee, Ting-Yim; St. Lawrence, Keith

2012-12-01

In many cases, kinetic modeling requires that the arterial input function (AIF)—the time-dependent arterial concentration of a tracer—be characterized. A straightforward method to measure the AIF of red and near-infrared optical dyes (e.g., indocyanine green) using a pulse oximeter is presented. The method is motivated by the ubiquity of pulse oximeters used in both preclinical and clinical applications, as well as the gap in currently available technologies to measure AIFs in small animals. The method is based on quantifying the interference that is observed in the derived arterial oxygen saturation (SaO2) following a bolus injection of a light-absorbing dye. In other words, the change in SaO2 can be converted into dye concentration knowing the chromophore-specific extinction coefficients, the true arterial oxygen saturation, and total hemoglobin concentration. A simple error analysis was performed to highlight potential limitations of the approach, and a validation of the method was conducted in rabbits by comparing the pulse oximetry method with the AIF acquired using a pulse dye densitometer. Considering that determining the AIF is required for performing quantitative tracer kinetics, this method provides a flexible tool for measuring the arterial dye concentration that could be used in a variety of applications.

Design and Evaluation of a Low-Cost Smartphone Pulse Oximeter

PubMed Central

Petersen, Christian L.; Chen, Tso P.; Ansermino, J. Mark; Dumont, Guy A.

2013-01-01

Infectious diseases such as pneumonia take the lives of millions of children in low- and middle-income countries every year. Many of these deaths could be prevented with the availability of robust and low-cost diagnostic tools using integrated sensor technology. Pulse oximetry in particular, offers a unique non-invasive and specific test for an increase in the severity of many infectious diseases such as pneumonia. If pulse oximetry could be delivered on widely available mobile phones, it could become a compelling solution to global health challenges. Many lives could be saved if this technology was disseminated effectively in the affected regions of the world to rescue patients from the fatal consequences of these infectious diseases. We describe the implementation of such an oximeter that interfaces a conventional clinical oximeter finger sensor with a smartphone through the headset jack audio interface, and present a simulator-based systematic verification system to be used for automated validation of the sensor interface on different smartphones and media players. An excellent agreement was found between the simulator and the audio oximeter for both oxygen saturation and heart rate over a wide range of optical transmission levels on 4th and 5th generations of the iPod Touch™ and iPhone™ devices. PMID:24322563

Accuracy of the Lifebox pulse oximeter during hypoxia in healthy volunteers.

PubMed

Dubowitz, G; Breyer, K; Lipnick, M; Sall, J W; Feiner, J; Ikeda, K; MacLeod, D B; Bickler, P E

2013-12-01

Pulse oximetry is a standard of care during anaesthesia in high-income countries. However, 70% of operating environments in low- and middle-income countries have no pulse oximeter. The 'Lifebox' oximetry project set out to bridge this gap with an inexpensive oximeter meeting CE (European Conformity) and ISO (International Organization for Standardization) standards. To date, there are no performance-specific accuracy data on this instrument. The aim of this study was to establish whether the Lifebox pulse oximeter provides clinically reliable haemoglobin oxygen saturation (Sp O2 ) readings meeting USA Food and Drug Administration 510(k) standards. Using healthy volunteers, inspired oxygen fraction was adjusted to produce arterial haemoglobin oxygen saturation (Sa O2 ) readings between 71% and 100% measured with a multi-wavelength oximeter. Lifebox accuracy was expressed using bias (Sp O2 - Sa O2 ), precision (SD of the bias) and the root mean square error (Arms). Simultaneous readings of Sa O2 and Sp O2 in 57 subjects showed a mean (SD) bias of -0.41% (2.28%) and Arms 2.31%. The Lifebox pulse oximeter meets current USA Food and Drug Administration standards for accuracy, thus representing an inexpensive solution for patient monitoring without compromising standards. © 2013 The Association of Anaesthetists of Great Britain and Ireland.

Cerebral arterial oxygen saturation measurements using a fiber-optic pulse oximeter.

PubMed

Phillips, J P; Langford, R M; Chang, S H; Maney, K; Kyriacou, P A; Jones, D P

2010-10-01

A pilot investigation was undertaken to assess the performance of a novel fiber-optic cerebral pulse oximetry system. A fiber-optic probe designed to pass through the lumen of a cranial bolt of the type used to make intracranial pressure measurements was used to obtain optical reflectance signals directly from brain tissue. Short-duration measurements were made in six patients undergoing neurosurgery. These were followed by a longer duration measurement in a patient recovering from an intracerebral hematoma. Estimations of cerebral arterial oxygen saturation derived from a frequency domain-based algorithm are compared with simultaneous pulse oximetry (SpO2) and hemoximeter (SaO2) blood samples. The short-duration measurements showed that reliable photoplethysmographic signals could be obtained from the brain tissue. In the long-duration study, the mean (±SD) difference between cerebral oxygen saturation (ScaO2) and finger SpO2 (in saturation units) was -7.47(±3.4)%. The mean (±SD) difference between ScaO2 and blood SaO2 was -7.37(±2.8)%. This pilot study demonstrated that arterial oxygen saturation may be estimated from brain tissue via a fiber-optic pulse oximeter used in conjunction with a cranial bolt. Further studies are needed to confirm the clinical utility of the technique.

Arterial input function of an optical tracer for dynamic contrast enhanced imaging can be determined from pulse oximetry oxygen saturation measurements.

PubMed

Elliott, Jonathan T; Wright, Eric A; Tichauer, Kenneth M; Diop, Mamadou; Morrison, Laura B; Pogue, Brian W; Lee, Ting-Yim; St Lawrence, Keith

2012-12-21

In many cases, kinetic modeling requires that the arterial input function (AIF)--the time-dependent arterial concentration of a tracer--be characterized. A straightforward method to measure the AIF of red and near-infrared optical dyes (e.g., indocyanine green) using a pulse oximeter is presented. The method is motivated by the ubiquity of pulse oximeters used in both preclinical and clinical applications, as well as the gap in currently available technologies to measure AIFs in small animals. The method is based on quantifying the interference that is observed in the derived arterial oxygen saturation (SaO₂) following a bolus injection of a light-absorbing dye. In other words, the change in SaO₂ can be converted into dye concentration knowing the chromophore-specific extinction coefficients, the true arterial oxygen saturation, and total hemoglobin concentration. A simple error analysis was performed to highlight potential limitations of the approach, and a validation of the method was conducted in rabbits by comparing the pulse oximetry method with the AIF acquired using a pulse dye densitometer. Considering that determining the AIF is required for performing quantitative tracer kinetics, this method provides a flexible tool for measuring the arterial dye concentration that could be used in a variety of applications.

Examiner's finger-mounted fetal tissue oximetry

NASA Astrophysics Data System (ADS)

Kanayama, Naohiro; Niwayama, Masatsugu

2014-06-01

The best way to assess fetal condition is to observe the oxygen status of the fetus (as well as to assess the condition of infants, children, and adults). Previously, several fetal oximeters have been developed; however, no instrument has been utilized in clinical practice because of the low-capturing rate of the fetal oxygen saturation. To overcome the problem, we developed a doctor's finger-mounted fetal tissue oximeter, whose sensor volume is one hundredth of the conventional one. Additionally, we prepared transparent gloves. The calculation algorithm of the hemoglobin concentration was derived from the light propagation analysis based on the transport theory. We measured neonatal and fetal oxygen saturation (StO2) with the new tissue oximeter. Neonatal StO was measured at any position of the head regardless of amount of hair. Neonatal StO was found to be around 77%. Fetal StO was detected in every position of the fetal head during labor regardless of the presence of labor pain. Fetal StO without labor pain was around 70% in the first stage of labor and around 60% in the second stage of labor. We concluded that our new concept of fetal tissue oximetry would be useful for detecting fetal StO in any condition of the fetus.

Cost and Cost-Effectiveness Assessments of Newborn Screening for Critical Congenital Heart Disease Using Pulse Oximetry: A Review.

PubMed

Grosse, Scott D; Peterson, Cora; Abouk, Rahi; Glidewell, Jill; Oster, Matthew E

2017-01-01

Screening newborns for critical congenital heart disease (CCHD) using pulse oximetry is recommended to allow for the prompt diagnosis and prevention of life-threatening crises. The present review summarizes and critiques six previously published estimates of the costs or cost-effectiveness of CCHD screening from the United Kingdom, United States, and China. Several elements that affect CCHD screening costs were assessed in varying numbers of studies, including screening staff time, instrumentation, and consumables, as well as costs of diagnosis and treatment. A previous US study that used conservative assumptions suggested that CCHD screening is likely to be considered cost-effective from the healthcare sector perspective. Newly available estimates of avoided infant CCHD deaths in several US states that implemented mandatory CCHD screening policies during 2011-2013 suggest a substantially larger reduction in deaths than was projected in the previous US cost-effectiveness analysis. Taking into account these new estimates, we estimate that cost per life-year gained could be as low as USD 12,000. However, that estimate does not take into account future costs of health care and education for surviving children with CCHD nor the costs incurred by health departments to support and monitor CCHD screening policies and programs.

Comparison of NIRS, laser Doppler flowmetry, photoplethysmography, and pulse oximetry during vascular occlusion challenges.

PubMed

Abay, T Y; Kyriacou, P A

2016-04-01

Monitoring changes in blood volume, blood flow, and oxygenation in tissues is of vital importance in fields such as reconstructive surgery and trauma medicine. Near infrared spectroscopy (NIRS), laser Doppler (LDF) flowmetry, photoplethysmography (PPG), and pulse oximetry (PO) contribute to such fields due to their safe and noninvasive nature. However, the techniques have been rarely investigated simultaneously or altogether. The aim of this study was to investigate all the techniques simultaneously on healthy subjects during vascular occlusion challenges. Sensors were attached on the forearm (NIRS and LDF) and fingers (PPG and PO) of 19 healthy volunteers. Different degrees of vascular occlusion were induced by inflating a pressure cuff on the upper arm. The responses of tissue oxygenation index (NIRS), tissue haemoglobin index (NIRS), flux (LDF), perfusion index (PPG), and arterial oxygen saturation (PO) have been recorded and analyzed. Moreover, the optical densities were calculated from slow varying dc PPG, in order to distinguish changes in venous blood volumes. The indexes showed significant changes (p  <  0.05) in almost all occlusions, either venous or over-systolic occlusions. However, differentiation between venous and arterial occlusion by LDF may be challenging and the perfusion index (PI) may not be adequate to indicate venous occlusions. Optical densities may be an additional tool to detect venous occlusions by PPG.

Wireless Monitoring of Liver Hemodynamics In Vivo

DOE PAGES

Akl, Tony J.; Wilson, Mark A.; Ericson, M. Nance; ...

2014-07-14

Liver transplants have their highest failure rate in the first two weeks following surgery. There are no devices for continuous, real-time monitoring of the graft, currently. Here, we present a continuous perfusion and oxygen consumption monitor based on photoplethysmography. The sensor is battery operated and communicates wirelessly with a data acquisition computer which provides the possibility of implantation provided sufficient miniaturization. In two in vivo porcine studies, the sensor tracked perfusion changes in hepatic tissue during vascular occlusions with a root mean square error (RMSE) of 0.125 mL/min/g of tissue. We show the possibility of using the pulsatile wave tomore » measure the arterial oxygen saturation similar to pulse oximetry. This signal is used as a feedback to extract the venous oxygen saturation from the DC levels. Arterial and venous oxygen saturation changes were measured with an RMSE of 2.19 and 1.39% respectively when no vascular occlusions were induced. The resulting error increased to 2.82 and 3.83% when vascular occlusions were induced during hypoxia. These errors are similar to the resolution of the oximetry catheter used as a reference. This work is the first realization of a wireless perfusion and oxygenation sensor for continuous monitoring of hepatic perfusion and oxygenation changes.« less

Cost and Cost-Effectiveness Assessments of Newborn Screening for Critical Congenital Heart Disease Using Pulse Oximetry: A Review

PubMed Central

Grosse, Scott D.; Peterson, Cora; Abouk, Rahi; Glidewell, Jill; Oster, Matthew E.

2018-01-01

Screening newborns for critical congenital heart disease (CCHD) using pulse oximetry is recommended to allow for the prompt diagnosis and prevention of life-threatening crises. The present review summarizes and critiques six previously published estimates of the costs or cost-effectiveness of CCHD screening from the United Kingdom, United States, and China. Several elements that affect CCHD screening costs were assessed in varying numbers of studies, including screening staff time, instrumentation, and consumables, as well as costs of diagnosis and treatment. A previous US study that used conservative assumptions suggested that CCHD screening is likely to be considered cost-effective from the healthcare sector perspective. Newly available estimates of avoided infant CCHD deaths in several US states that implemented mandatory CCHD screening policies during 2011–2013 suggest a substantially larger reduction in deaths than was projected in the previous US cost-effectiveness analysis. Taking into account these new estimates, we estimate that cost per life-year gained could be as low as USD 12,000. However, that estimate does not take into account future costs of health care and education for surviving children with CCHD nor the costs incurred by health departments to support and monitor CCHD screening policies and programs. PMID:29376140

Nocturnal Oxygen Desaturation Index is Inversely Correlated with Airflow Limitation in Patients with Chronic Obstructive Pulmonary Disease.

PubMed

Tamai, Koji; Matsuoka, Hirofumi; Suzuki, Yujiro; Yoshimatsu, Harukazu; Masuya, Daiki; Nakashima, Nariyasu; Okada, Nobuhiko; Oda, Nao; Inoue, Sayaka; Koma, Yasuko; Otsuka, Akiko

2016-01-01

The concurrent diagnosis of chronic obstructive pulmonary disease (COPD) and sleep apnoea-hypopnoea syndrome (SAHS) (overlap syndrome), can contribute to worsening respiratory symptoms, but whether the severity of COPD is associated with co-morbid SAHS is unknown. We investigated whether the severity of COPD is associated with the complication of SAHS by examination of nocturnal oximetry as an alternative to polysomnography. Patients with COPD concurrently completed nocturnal oximetry, pulmonary function tests, a COPD assessment test, an Epworth sleepiness scale and a hospital anxiety and depression scale to evaluate the severity of COPD and possible concurrent presence of SAHS. We retrospectively analysed the data to assess correlation between the oxygen desaturation index (ODI) and each clinical variables and evaluated the predictors of ODI ≥ 15. This study included 103 patients (91 males, 88%) with a mean age of 72 ± 8 years and body mass index of 22 ± 3 kg/m(2). ODI was positively correlated with FEV1, FEV1/FVC and FEV1% predicted, which meant that ODI was inversely correlated with airflow limitation. Univariate logistic regression analysis revealed that FEV1% predicted and FEV1/FVC were predictors of ODI ≥ 15. ODI is inversely correlated with airflow limitation and milder COPD patients may have co-morbid SAHS.

Wearable Pulse Oximetry Measurements on the Torso, Arms, and Legs: A Proof of Concept.

PubMed

Kramer, Marcus; Lobbestael, Aaron; Barten, Emily; Eian, John; Rausch, Gregory

2017-03-01

For decades pulse oximeters designed for use on the head, hands, or feet have provided invaluable estimates of oxygen saturation to medical personal attending to combat casualties. However, traditional placement sites are not ideal for the relatively new paradigm of continuous battlefield telemonitoring. To assess the feasibility of oximetry on nontraditional body sites, 42 healthy volunteers were enrolled, consented, and underwent an industry standard induced-hypoxia study. During the study volunteers used prototype wearable oximeters, designed for the torso, arms, and legs. Subsets (size n) of the volunteers had the wearables placed at the following body sites, and achieved accuracies (A RMS , root-mean-square difference) of the following: calf 1.7% (n = 26); bicep 3.1% (n = 12); forearm 3.4% (n = 11); pectoral 2.9% (n = 42); sternum 2.9% (n = 13). In keeping with regulatory guidance calibrations with an A RMS of less than 3.5% are acceptable for potential future development. Additionally, a new method was developed to enable accurate reporting of respiration rate from the pectoral oximeter, A RMS of 1.1 breaths per minute (n = 10). This study demonstrates the feasibility of monitoring oxygen saturation and respiration rate from nontraditional sites via a wearable pulse oximeter. Reprint & Copyright © 2017 Association of Military Surgeons of the U.S.

Detection of Hb Rothschild HBB: c.[112T>A or 112T>C], Through High Index of Suspicion on Abnormal Pulse Oximetry.

PubMed

Alli, Nazeer A; Wessels, Piet; Rampersad, Narisha; Clark, Barnaby E; Thein, Swee Lay

2017-03-01

We describe a case with a low oxygen affinity hemoglobin (Hb) variant who presented with cyanosis in the absence of cardiopulmonary disease. The patient, a 27-year-old pregnant female (P1G2), complained of a productive cough and bluish discoloration of the lips that started 3 days prior to seeking attention. She had no previous episodes and has generally been in good health. A positive family history of cyanosis was obtained in one sibling. Systematic examination, notably the cardiorespiratory system, revealed no abnormalities. The arterial Hb oxygen saturation (SpO 2 ) on pulse oximetry was 81.0% and Hb separation studies revealed an Hb variant identified as Hb Rothschild [β37(C3)Trp→Arg] (HBB: c.[112 T>A or 112 T>C]) by gene sequencing. The amino acid substitution (Trp→Arg) is an important contact point at the α1β2 interface and favors a T-quaternary state of the Hb tetramer. This leads to a low oxygen affinity state, which results in premature release of oxygen and drop in oxygen saturation. In the absence of cardiopulmonary disease, a decreased oxygen saturation reading, with or without cyanosis, should arouse suspicion for a possible dysHb.

Accuracy of Noninvasive Hemoglobin Monitoring in Patients at Risk for Hemorrhage

DTIC Science & Technology

2014-01-01

a noninvasive, spectrophotometry-based moni- toring technology (Radical-7 Pulse CO- Oximeter ; Masimo Corp., Irvine, CA) that provides continuous Hgb...sensor. The sensor was placed on the first or second digit on the hand opposite the clinical pulse oximeter sensor whenever possible. If the need arose...in a method similar to conventional pulse oximetry. Transmitted light is captured by photodiode receptor and ana- lyzed to create an analog signal that

The Toxicity of Inhaled Sulphur Mustard

DTIC Science & Technology

2012-03-01

Pulse oximetry Mean arterial pressure Central venous pressure Blood Chemistry (arterial and venous ) pH pO2 pCO2 Sodium Potassium Calcium...Cardiovascular Parameters − CFI – Cardiac Function Index − CO – Cardiac Output − CvO2 – Mixed Venous Oxygenation − CVP – Central Venous Pressure...Data are expressed as mean ± SEM. Changes in central venous pressure following exposure to HD: HD controls () and HD + NAC (). Data are

Spectroscopy and imaging of oxygen delivery to tissue under strenuous conditions (NIR in athletes)

NASA Astrophysics Data System (ADS)

Chance, Britton; Nioka, Shoko; Long, Hong; Xie, Chunhua; Ma, XuHui; Ntziachristos, Vasilis; Luo, Qingming

2000-04-01

It was demonstrated that the dynamics of muscle oxygen utilization can readily be measured using dual wavelength hemoglobin oximetry. This method can be used for muscle training exercise and also for evaluation of exercise performance where the anaerobic threshold must be avoided. It was shown that CW imaging technology gives images along the surface of the muscle while the time resolved spectroscopy gives images transverse to the muscle.

Hypertonic Saline Dextran (HSD) in a Complex Military Injury - A Preclinical Study

DTIC Science & Technology

2010-04-01

applicable to civilian settings e.g. after terrorist bombings where there is often disruption to infrastructure and security issues relating to secondary... systemic inflammatory response that develops after trauma and which is thought to be part of the aetiology underlying later complications [19- 22...consisted of end-tidal CO2, pulse oximetry via a tail probe and skin surface electrocardiogram electrodes (Propac 106EL, Protocol Systems Inc., Oregon

TH-AB-209-05: Validating Hemoglobin Saturation and Dissolved Oxygen in Tumors Using Photoacoustic Computed Tomographic Spectroscopic Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burnett, J; Sick, J; Liu, B

Purpose: Photoacoustic computed tomographic spectroscopy (PCT-S) provides intra-tumor measurements of oxygenation with high spatial resolution (0.2mm) and temporal fidelity (1–2 minutes) without the need for exogenous agents or ionizing radiation, thus providing a unique in vivo assay to measure SaO{sub 2} and investigate acute and chronic forms of hypoxia. The goal of this study is to validate in vivo SaO{sub 2} levels within tail artery of mice and the relationship between SaO{sub 2} and pO{sub 2} within subcutaneous breast tumors using PCT-S imaging, pulse oximetry and an OxyLite probe. Methods: A closed circuit phantom was fabricated to control blood oxygenationmore » levels, where SaO{sub 2} was measured using a co-oximeter and pO{sub 2} using an Oxylite probe. Next, SaO{sub 2} levels within the tail arteries of mice (n=3) were measured using PCT-S and pulse oximetry while breathing high-to-low oxygen levels (6-cycles). Finally, PCT-S was used to measure SaO{sub 2} levels in MCF-7, MCF-7-VEGF165, and MDA-MB-231 xenograft breast tumors and compared to Oxylite pO{sub 2} levels values. Results: SaO{sub 2} and pO{sub 2} data obtained from the calibration phantom was fit to Hill’s equation: aO{sub 2} levels between 88 and 52% demonstrated a linear relationship (r2=0.96) and a 3.2% uncertainty between PCT-S values relative to pulse oximetry. Scatter plots of localized PCT-S measured SaO2 and Oxylite pO{sub 2} levels in MCF-7/MCF-7-VEGF165 and MDA-MD-231 breast tumors were fit to Hill’s equation: P50=17.2 and 20.7mmHg, and n=1.76 and 1.63. These results are consistent with sigmoidal form of Hill’s equation, where the lower P{sub 50} value is indicative of an acidic tumor microenvironment. Conclusion: The results demonstrate photoacoustic imaging can be used to measure SaO{sub 2} cycling and intra-tumor oxygenation, and provides a powerful in vivo assay to investigate the role of hypoxia in radiation, anti-angiogenic, and immunotherapies.« less

In vivo evidence of methamphetamine induced attenuation of brain tissue oxygenation as measured by EPR oximetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weaver, John, E-mail: jmweaver@salud.unm.edu; Department of Pharmaceutical Sciences, College of Pharmacy, University of New Mexico Health Sciences Center, Albuquerque, NM 87131; Yang, Yirong

2014-03-01

Abuse of methamphetamine (METH) is a major and significant societal problem in the US, as a number of studies have suggested that METH is associated with increased cerebrovascular events, hemorrhage or vasospasm. Although cellular and molecular mechanisms involved in METH-induced toxicity are not completely understood, changes in brain O{sub 2} may play an important role and contribute to METH-induced neurotoxicity including dopaminergic receptor degradation. Given that O{sub 2} is the terminal electron acceptor for many enzymes that are important in brain function, the impact of METH on brain tissue pO{sub 2}in vivo remains largely uncharacterized. This study investigated striatal tissuemore » pO{sub 2} changes in male C57BL/6 mice (16–20 g) following METH administration using EPR oximetry, a highly sensitive modality to measure pO{sub 2}in vivo, in situ and in real time. We demonstrate that 20 min after a single injection of METH (8 mg/kg i.v.), the striatal pO{sub 2} was reduced to 81% of the pretreatment level and exposure to METH for 3 consecutive days further attenuated striatal pO{sub 2} to 64%. More importantly, pO{sub 2} did not recover fully to control levels even 24 h after administration of a single dose of METH and continual exposure to METH exacerbates the condition. We also show a reduction in cerebral blood flow associated with a decreased brain pO{sub 2} indicating an ischemic condition. Our findings suggests that administration of METH can attenuate brain tissue pO{sub 2}, which may lead to hypoxic insult, thus a risk factor for METH-induced brain injury and the development of stroke in young adults. - Highlights: • Explored striatal tissue pO{sub 2}in vivo after METH administration by EPR oximetry. • pO{sub 2} was reduced by 81% after a single dose and 64% after 3 consecutive daily doses. • pO{sub 2} did not recover fully to control levels even 24 h after a single dose. • Decrease in brain tissue pO{sub 2} may be associated with a decrease in CBF. • Administration of methamphetamine may lead to hypoxic insult.« less

Pulse oximetry findings in newborns with antenatally diagnosed congenital heart disease.

PubMed

Mawson, Isabel E; Babu, Pratusha L; Simpson, John M; Fox, Grenville F

2018-05-01

A retrospective review of admission preductal oxygen saturations of neonates with antenatally diagnosed critical congenital heart disease (CCHD) was performed to investigate the differences in newborn pulse oximetry (Pulsox) by specific CCHD diagnosis. Saturations were recorded at median of < 1 h (range < 1-9 h) after delivery. Data was stratified by CCHD diagnosis and analysed according to the three different admission Pulsox thresholds, ≤ 90, ≤ 92 and ≤ 95%. Of the 276 neonates studied, 208 were clinically well at admission, with no co-morbidities, gestation > 34 weeks and birth weight > 1.8 kg. A statistically significant increase in the proportion with low admission saturations was seen using ≤ 95% saturation threshold (72% (95% CI 66-78)) compared to ≤ 92% (52% (95% CI 46-59)) and ≤ 90% (46% (95% CI 39-52)). Sub-group analysis found the proportion of neonates with low saturations varied according to the specific CCHD diagnosis with only 20-42% of neonates with aortic stenosis, coarctation of the aorta and pulmonary stenosis having saturations ≤ 95%. The proportion of neonates with low admission oxygen saturation varied by CCHD diagnosis with those without critically reduced pulmonary blood flow not having low admission saturations, in general, even using the ≤ 95% threshold which had the highest proportions of abnormal saturations. This data may assist developing Pulsox screening policies. What is Known: • The addition of pulse oximetry (Pulsox) screening to the routine newborn examination increases the sensitivity of CCHD detection. Pulsox screening is also highly specific for CCHD in asymptomatic neonates, with low false-positive rates. • Early diagnosis of CCHD improves patient outcomes in relation to both morbidity and mortality. What is New: • The proportion of affected infants with an abnormal Pulsox result varies by CCHD diagnosis and screening threshold. In our study using the ≤ 95% threshold gave the highest proportion of neonates with abnormal saturations at admission. • In general, Pulsox yield of abnormal results is low for CCHD diagnoses not associated with critically reduced pulmonary blood flow; however, increasing the Pulsox threshold increased the proportion of infants with an abnormal result.

Mobile, Multimodal, Label-Free Imaging Probe Analysis of Choroidal Oximetry and Retinal Hypoxia

DTIC Science & Technology

2017-12-01

these same eye injuries. Primary blast-induced injury (PBI), which can occur in eyes that are not punctured or ruptured by the blast, is correlated ...optimization. (1A-F) The component of our PBI- devices, output pressure detection sensor, amplifier, and input pressure panel. (1G) Correlation between...by changing the setting of blast generator. (2A-B) Correlation between output pressure and blast time duration. (2C) After PBI- treatment, the eyes of

Relationship of Hemoglobin to Arterial Oxygen Desaturation during Aeromedical Evacuation

DTIC Science & Technology

2015-04-02

consent was obtained, a portable pulse oximeter (Rad-57, Masimo Corp., Irvine, CA) was attached to the subject via an adhesive, disposable finger sensor...The oximeter noninvasively measured and recorded arterial SpO2, PR, Hgb, and pulse index every 2 seconds. The oximeter’s screen was covered so as...studied. For this study, subjects deemed safe to fly by the validating flight surgeon were monitored with pulse oximetry from the flight line until arrival

Evaluation of SOCOM Wireless Monitor in Trauma Patients

DTIC Science & Technology

2013-02-01

pulse   oximeter  consistently  underestimates  O2   saturation  and   does  not  reliably  follow  changes  in  O2...fingertip   sensor   detects:   arterial   saturation   by   pulse   oximetry   (SpO2),   heart   rate  derived  from  R  wave...prehospital  run  reports.    These  data    suggest  that   the  R

The Toxicity of Inhaled Sulphur Mustard

DTIC Science & Technology

2012-10-01

Index − CO – Cardiac Output − CvO2 – Mixed Venous Oxygenation − CVP – Central Venous Pressure − DO2 – Oxygen Delivery − dpMax – Maximum...in central venous pressure following exposure to HD: HD controls () and HD + NAC (). Data are expressed as mean ± SEM. UK UNCLASSIFIED Page 64 of...Respiratory rate (RR) Heart rate (HR) Expired CO2 Pulse oximetry Mean arterial pressure Central venous pressure Blood Chemistry (arterial and

[Effect of dexmedetomidine on perfusion of free flaps transferred to head and neck].

PubMed

Dobrodeev, A S; Rabinovich, S A; Malykhina, I F

The paper presents the impact of perioperative care on feasibility of free fibula flap transfer for facial reconstruction. Flaps vitality was measured by means of somatic oximetry in 85 patients aged 20-74 years receiving reconstruction procedures in midfacial and lower facial areas. The patients were divided in three groups according to sedation agent used postoperatively. It has been demonstrated that dexmedetomidine postoperative sedation significantly improved free fibula flaps perfusion compared to propofol sedation.

Ultra-low-cost clinical pulse oximetry.

PubMed

Petersen, Christian L; Gan, Heng; MacInnis, Martin J; Dumont, Guy A; Ansermino, J Mark

2013-01-01

An ultra-low-cost pulse oximeter is presented that interfaces a conventional clinical finger sensor with a mobile phone through the headset jack audio interface. All signal processing is performed using the audio subsystem of the phone. In a preliminary volunteer study in a hypoxia chamber, we compared the oxygen saturation obtained with the audio pulse oximeter against a commercially available (and FDA approved) reference pulse oximeter (Nonin Xpod). Good agreement was found between the outputs of the two devices.

Evaluation of pulse-oximetry oxygen saturation taken through skin protective covering

PubMed Central

James, Jyotsna; Tiwari, Lokesh; Upadhyay, Pramod; Sreenivas, Vishnubhatla; Bhambhani, Vikas; Puliyel, Jacob M

2006-01-01

Background The hard edges of adult finger clip probes of the pulse oximetry oxygen saturation (POOS) monitor can cause skin damage if used for prolonged periods in a neonate. Covering the skin under the probe with Micropore surgical tape or a gauze piece might prevent such injury. The study was done to see if the protective covering would affect the accuracy of the readings. Methods POOS was studied in 50 full-term neonates in the first week of life. After obtaining consent from their parents the neonates had POOS readings taken directly (standard technique) and through the protective covering. Bland-Altman plots were used to compare the new method with the standard technique. A test of repeatability for each method was also performed. Results The Bland-Altman plots suggest that there is no significant loss of accuracy when readings are taken through the protective covering. The mean difference was 0.06 (SD of 1.39) and 0.04 (SD 1.3) with Micropore and gauze respectively compared to the standard method. The mean difference was 0.22 (SD 0.23) on testing repeatability with the standard method. Conclusion Interposing Micropore or gauze does not significantly affect the accuracy of the POOS reading. The difference between the standard method and the new method was less than the difference seen on testing repeatability of the standard method. PMID:16677394

Evaluation of pulse-oximetry oxygen saturation taken through skin protective covering.

PubMed

James, Jyotsna; Tiwari, Lokesh; Upadhyay, Pramod; Sreenivas, Vishnubhatla; Bhambhani, Vikas; Puliyel, Jacob M

2006-05-06

The hard edges of adult finger clip probes of the pulse oximetry oxygen saturation (POOS) monitor can cause skin damage if used for prolonged periods in a neonate. Covering the skin under the probe with Micropore surgical tape or a gauze piece might prevent such injury. The study was done to see if the protective covering would affect the accuracy of the readings. POOS was studied in 50 full-term neonates in the first week of life. After obtaining consent from their parents the neonates had POOS readings taken directly (standard technique) and through the protective covering. Bland-Altman plots were used to compare the new method with the standard technique. A test of repeatability for each method was also performed. The Bland-Altman plots suggest that there is no significant loss of accuracy when readings are taken through the protective covering. The mean difference was 0.06 (SD of 1.39) and 0.04 (SD 1.3) with Micropore and gauze respectively compared to the standard method. The mean difference was 0.22 (SD 0.23) on testing repeatability with the standard method. Interposing Micropore or gauze does not significantly affect the accuracy of the POOS reading. The difference between the standard method and the new method was less than the difference seen on testing repeatability of the standard method.

Clinical EPR: Unique Opportunities and Some Challenges

PubMed Central

Swartz, Harold M.; Williams, Benjamin B.; Zaki, Bassem I.; Hartford, Alan C.; Jarvis, Lesley A.; Chen, Eunice; Comi, Richard J.; Ernstoff, Marc S.; Hou, Huagang; Khan, Nadeem; Swarts, Steven G.; Flood, Ann B.; Kuppusamy, Periannan

2014-01-01

Electron paramagnetic resonance (EPR) spectroscopy has been well established as a viable technique for measurement of free radicals and oxygen in biological systems, from in vitro cellular systems to in vivo small animal models of disease. However, the use of EPR in human subjects in the clinical setting, although attractive for a variety of important applications such as oxygen measurement, is challenged with several factors including the need for instrumentation customized for human subjects, probe and regulatory constraints. This paper describes the rationale and development of the first clinical EPR systems for two important clinical applications, namely, measurement of tissue oxygen (oximetry), and radiation dose (dosimetry) in humans. The clinical spectrometers operate at 1.2 GHz frequency and use surface loop resonators capable of providing topical measurements up to 1 cm depth in tissues. Tissue pO2 measurements can be carried out noninvasively and repeatedly after placement of an oxygen-sensitive paramagnetic material (currently India ink) at the site of interest. Our EPR dosimetry system is capable of measuring radiation-induced free radicals in the tooth of irradiated human subjects to determine the exposure dose. These developments offer potential opportunities for clinical dosimetry and oximetry, which include guiding therapy for individual patients with tumors or vascular disease, by monitoring of tissue oxygenation. Further work is in progress to translate this unique technology to routine clinical practice. PMID:24439333

Accuracy of pulse oximetry measurement of heart rate of newborn infants in the delivery room.

PubMed

Kamlin, C Omar F; Dawson, Jennifer A; O'Donnell, Colm P F; Morley, Colin J; Donath, Susan M; Sekhon, Jasbir; Davis, Peter G

2008-06-01

To determine the accuracy of heart rate obtained by pulse oximetry (HR(PO)) relative to HR obtained by 3-lead electrocardiography (HR(ECG)) in newborn infants in the delivery room. Immediately after birth, a preductal PO sensor and ECG leads were applied. PO and ECG monitor displays were recorded by a video camera. Two investigators reviewed the videos. Every two seconds, 1 of the investigators recorded HR(PO) and indicators of signal quality from the oximeter while masked to ECG, whereas the other recorded HR(ECG) and ECG signal quality while masked to PO. HR(PO) and HR(ECG) measurements were compared using Bland-Altman analysis. We attended 92 deliveries; 37 infants were excluded due to equipment malfunction. The 55 infants studied had a mean (+/-standard deviation [SD]) gestational age of 35 (+/-3.7) weeks, and birth weight 2399 (+/-869) g. In total, we analyzed 5877 data pairs. The mean difference (+/-2 SD) between HR(ECG) and HR(PO) was -2 (+/-26) beats per minute (bpm) overall and -0.5 (+/-16) bpm in those infants who received positive-pressure ventilation and/or cardiac massage. The sensitivity and specificity of PO for detecting HR(ECG) <100 bpm was 89% and 99%, respectively. PO provided an accurate display of newborn infants' HR in the delivery room, including those infants receiving advanced resuscitation.

Assessment of oxygen saturation in dental pulp of permanent teeth with periodontal disease.

PubMed

Giovanella, Larissa Bergesch; Barletta, Fernando Branco; Felippe, Wilson Tadeu; Bruno, Kely Firmino; de Alencar, Ana Helena Gonçalves; Estrela, Carlos

2014-12-01

In individuals with periodontal disease, dental pulp status should be determined before a treatment plan is made. Pulse oximeters are promising diagnostic tools to evaluate pulp vascularization. This study used pulse oximetry to determine the level of oxygen saturation in dental pulp of intact permanent teeth with periodontal attachment loss (PAL) and gingival recession (GR) and to evaluate the correlation between periodontal disease and level of oxygen saturation in the pulp. This study included 67 anterior teeth of 35 patients; all teeth showed intact crowns, PAL, a periodontal pocket (PP), and GR. The teeth underwent periodontal examination, cold and electric pulp testing, and pulse oximetry measurements. The Pearson correlation coefficient and a linear regression coefficient were calculated to evaluate the degree of correlation between periodontal disease markers (PAL, PP, and GR) and the level of oxygen saturation in dental pulp. These tests also evaluated possible associations between oxygen saturation and cold and electric pulp testing. PAL, PP, and GR had negative correlations with oxygen saturation in dental pulp. Conversely, no statistically significant association was found between oxygen saturation in dental pulp and the response to electric sensibility testing. Oxygen saturation was lower in the pulp of permanent teeth with PAL, PP, and GR, indicating that periodontal disease correlates with the level of oxygen saturation in the pulp. Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Oximetry in children recovering from deep hypothermia for cardiac surgery.

PubMed

Macnab, A J; Baker-Brown, G; Anderson, E E

1990-10-01

Although pulse oximetry is a potentially useful diagnostic tool in the treatment of children after major open heart surgery, there are concerns regarding its reliability for measuring oxygen saturation (SaO2) in hypothermic or low perfusion states. To test pulse oximeter reliability in children under these conditions, our study compared 187 SaO2 pulse oximeter readings (Biox 3700) with simultaneous hemoximeter (OSM2, Radiometer) readings from 56 children rewarming after open heart surgery. Ages ranged from 4 months to 18 yr; temperatures ranged from 23.5 degrees to 38 degrees C (toe) and 31.3 degrees to 40.8 degrees C (core). The mean pulse oximeter SaO2 reading was 94.90% (SD 7.18, range 54% to 100%), mean hemoximeter reading was 96.07% (SD 7.06; minimum 54%; maximum 100%). The correlation between the readings was high (r = .88, p less than .005), and was not affected by low core temperature. When oximeter and cardiac monitor pulse rates coincided, the oximeter SaO2 value was within +/- 5% (p less than .05). We conclude that the Biox 3700 oximeter is reliable for noninvasive SaO2 monitoring in mild to moderately hypothermic children after open heart surgery, particularly when oximeter and cardiac heart rates coincide. Further studies are needed to confirm our findings in children with core temperatures less than 31.3 degrees C, and when other oximeters are used.

Comparison between fluorimetry and oximetry techniques to measure photosynthesis in the diatom Skeletonema costatum cultivated under simulated seasonal conditions.

PubMed

Lefebvre, Sébastien; Mouget, Jean-Luc; Loret, Pascale; Rosa, Philippe; Tremblin, Gérard

2007-02-01

This study reports comparison of two techniques measuring photosynthesis in the ubiquitous diatom Skeletonema costatum, i.e., the classical oximetry and the recent modulated fluorimetry. Microalgae in semi-continuous cultures were exposed to five different environmental conditions simulating a seasonal effect with co-varying temperature, photoperiod and incident light. Photosynthesis was assessed by gross rate of oxygen evolution (P(B)) and the electron transport rate (ETR) measurements. The two techniques were linearly related within seasonal treatments along the course of the P/E curves. The light saturation intensity parameters (Ek and Ek(ETR)), and the maximum electron transport rate increased significantly with the progression of the season while the maximum light utilization efficiency for ETR (alpha(ETR)) was constant. By contrast, the maximum gross oxygen photosynthetic capacity (Pmax(B)) and the maximum light utilization efficiency for P(B) (alpha(B)) increased from December to May treatment but decreased from May to July treatment. Both techniques showed clear photoacclimation in microalgae with the progression of the season, as illustrated by changes in photosynthetic parameters. The relationship between the two techniques changed when high temperature, photoperiod and incident light were combined, possibly due to an overestimation of the PAR--averaged chlorophyll-specific absorption cross-section. Despite this change, our results illustrate the strong suitability of in vivo chlorophyll fluorimetry to estimate primary production in the field.

Retinal Oxygen: from animals to humans

PubMed Central

Linsenmeier, Robert A.; Zhang, Hao F.

2017-01-01

This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O2 in the retina: measurements of PO2 with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O2 concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO2 in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory. PMID:28109737

Design of a visible-light spectroscopy clinical tissue oximeter.

PubMed

Benaron, David A; Parachikov, Ilian H; Cheong, Wai-Fung; Friedland, Shai; Rubinsky, Boris E; Otten, David M; Liu, Frank W H; Levinson, Carl J; Murphy, Aileen L; Price, John W; Talmi, Yair; Weersing, James P; Duckworth, Joshua L; Hörchner, Uwe B; Kermit, Eben L

2005-01-01

We develop a clinical visible-light spectroscopy (VLS) tissue oximeter. Unlike currently approved near-infrared spectroscopy (NIRS) or pulse oximetry (SpO2%), VLS relies on locally absorbed, shallow-penetrating visible light (475 to 625 nm) for the monitoring of microvascular hemoglobin oxygen saturation (StO2%), allowing incorporation into therapeutic catheters and probes. A range of probes is developed, including noncontact wands, invasive catheters, and penetrating needles with injection ports. Data are collected from: 1. probes, standards, and reference solutions to optimize each component; 2. ex vivo hemoglobin solutions analyzed for StO2% and pO2 during deoxygenation; and 3. human subject skin and mucosal tissue surfaces. Results show that differential VLS allows extraction of features and minimization of scattering effects, in vitro VLS oximetry reproduces the expected sigmoid hemoglobin binding curve, and in vivo VLS spectroscopy of human tissue allows for real-time monitoring (e.g., gastrointestinal mucosal saturation 69+/-4%, n=804; gastrointestinal tumor saturation 45+/-23%, n=14; and p<0.0001), with reproducible values and small standard deviations (SDs) in normal tissues. FDA approved VLS systems began shipping earlier this year. We conclude that VLS is suitable for the real-time collection of spectroscopic and oximetric data from human tissues, and that a VLS oximeter has application to the monitoring of localized subsurface hemoglobin oxygen saturation in the microvascular tissue spaces of human subjects.

Operational and Systems Requirements for an In-Flight and Field Portable Laboratory.

DTIC Science & Technology

1992-04-01

MENTPEAIOASADSYTM REIWIANALYSIS TE N M NA CH ONLRPR SUPPFiguT 2. Sequence of OU events. EVAC ATIO MIS ION3 First, the applicable parts of the AE...Systems, Inc. CSI 501 John Bunn Co. OXI-Pulse Healthdyne Model 930 Kontron Instruments 7840, 7845 Marquest PULSOX-7 Nelicor N-10, N-100, N-200, N-1000...Ries, Andrew L.; Prewitt, Lela M.; Johnson, Jeffery J., Skin Color and Ear Oximetry. Chs . 96/2, pp. 287-290 (August 1989). 13. Riley, J. B.; Burgess, B

Green Light Pulse Oximeter

DOEpatents

Scharf, John Edward

1998-11-03

A reflectance pulse oximeter that determines oxygen saturation of hemoglobin using two sources of electromagnetic radiation in the green optical region, which provides the maximum reflectance pulsation spectrum. The use of green light allows placement of an oximetry probe at central body sites (e.g., wrist, thigh, abdomen, forehead, scalp, and back). Preferably, the two green light sources alternately emit light at 560 nm and 577 nm, respectively, which gives the biggest difference in hemoglobin extinction coefficients between deoxyhemoglobin, RHb, and oxyhemoglobin, HbO.sub.2.

Evaluation of the Human/Extreme Environment Interaction: Implications for Enhancing Operational Performance and Recovery

DTIC Science & Technology

2014-02-01

and 4 hours during the recovery using a pulse oximeter (Nonin Onyx II 9550, Plymouth, MN). Analysis Skeletal Muscle RNA isolation. An 8-20...Oximetry. Blood oxygen saturation was evaluated before and after exercise, and during recovery at 0:30, 2:30, 4:30, and 6:00 using a pulse oximeter ...cycling for 45 minutes, post exercise, and every hour during the 6-hour recovery using pulse oximeter (Nonin Onyx Finger Pulse Oximeter , Nonin Medical

Sensor system for non-invasive optical carboxy-and methemoglobin determination

NASA Astrophysics Data System (ADS)

Timm, Ulrich; Gewiss, Helge; Kraitl, Jens; Brock, Beate; Ewald, Hartmut

2017-02-01

The pulse oximetry is a non-invasive method to monitor the oxygen saturation and is clinically used for many years. However this technology has some limitations. In case of the presence of dysfunctional hemoglobin derivatives as carboxyhemoglobin (COHb) or methemoglobin (MetHb) the readings of the pulse oximeter are distorted. This erroneous diagnosis of the patient's status can result in a life threatening situation. This paper will describe a sensor system for noninvasive determination of carboxy- and methemoglobin.

Evaluation of the Human/Extreme Environment Interaction: Implications for Enhancing Operational Performance and Recovery

DTIC Science & Technology

2012-10-01

saturation was evaluated before and after exercise, and during recovery at 0:30, 2:30, 4:30, and 6:00 using a pulse oximeter (Nonin Onyx II 9550, Plymouth...Each collection was collected for 5 min, with the last 3 min averaged to represent the sample period. Pulse Oximetry. Blood oxygen ...would lead to more ATP per molecule of oxygen . The paradox with short-term and long-term metabolic adaptations is yet to be completely understood

[Cerebral oximetry in pulmonary thromboendarterectomy with circulatory arrest].

PubMed

Catalán Escudero, P; González Román, A; Serra Ruiz, C N; Barbero Mielgo, M; García Fernández, J

2014-02-01

Pulmonary thromboendarterectomy is an uncommon procedure and should be performed with circulatory arrest. One of the major concerns is the postoperative central neurological injuries. Perioperative brain oxygen monitoring is advisable in this surgical procedure for the early detection of brain hypoperfusion episodes and their intensity as well as any other postoperative episodes that can deteriorate the neurological outcome. Copyright © 2012 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.

Physiological and Medical Monitoring for En Route Care of Combat Casualties

DTIC Science & Technology

2008-04-01

Houston, TX 78234-6315; email: victor.convertino@amedd.army.mil. DOI: 10.1097/TA.0b013e31816c82f4 The Journal of TRAUMA Injury, Infection , and...device (A) and the LBNP protocol (B). The Journal of TRAUMA Injury, Infection , and Critical Care S344 April Supplement 2008 negative pressure induces...saturation ( SpO2 ; pulse oximetry), and tissue (muscle) PO2 and pH (near-infrared spectroscopy) in con- scious human subjects exposed to progressive

Manual Vital Signs Reliably Predict Need for Life-Saving Interventions in Trauma Patients

DTIC Science & Technology

2005-10-01

and pulse oximetry ( SpO2 ); and Group 3, Group 2 plus fully automated noninvasive blood pressure measurements, heart rate, end-tidal carbon dioxide, and... Infection , and Critical Care Volume 59 • Number 4 821 Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of...pulse character were not ini- tially recorded and resulted in elimination of 339 records created from August 2001 until May 2002. Analysis of the SpO2

Normobaric Hypoxia as a Cognitive Stress Test for Mild Traumatic Brain Injury: Oculometrics, Pulse Oximetry, and the Self Report of Symptom Severity

DTIC Science & Technology

2011-06-20

USAMRMC Reg 70-25 on Use of Volunteers in Research. Standard Form 298 (Rev. 8 /98) REPORT DOCUMENTATION PAGE Prescribed by ANSI Std. Z39.18 Form...ORGANIZATION NAME(S) AND ADDRESS(ES) 8 . PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR...group of control subjects ......................................28  8 . Saccadic velocity as a function of hypoxic condition averaged for the group of mild

VatuximabTM: Optimizing Therapeutic Strategies for Prostate Cancer Based on Dynamic MR Tumor Oximetry

DTIC Science & Technology

2007-12-01

Figure 19 Growth curves for H tumors with respect to bavituximab therapy. Growth curves for groups of control and bavituximab...a large tumor designated by green label received equivalent dose of control , antibody rituximab. 0.1 1 10 1 3 5 8 11 13 15 17 19 21 days...Figure 22 Growth curves for groups of treated AT1 tumors Purple * control untreated tumors; brown ● bavituximab at 2.5 mg/kg thrice weekly

Living for Six Days at 2200 M Improves Time-Trial Performance of Sea-Level Residents Exposed to 4300 M

DTIC Science & Technology

2008-02-01

breathing circuit by a rubber mouthpiece and nose clip, and to a finger pulse oximeter unit (Model 8600, Nonin Medical, Inc., Plymouth, MN) to...SaO2 via noninvasive finger pulse oximetry (Model 8600, Nonin Medical, Inc, Plymouth, MN) were monitored continuously, and ratings of perceived...respectively. Arterialization was achieved by warming the hand in 43ºC water for 5 min prior to obtaining a 150 µL fingertip blood sample for the

Therapeutic Vascular Targeting and Irradiation: Correlation of MRI and Tissue Changes at Cellular and Molecular Levels to Optimizing Outcome

DTIC Science & Technology

2005-06-01

subsequently trigger a cascade of tumor cell death in experimental tumors [4,5]. Although massive necrosis can be induced, tumors usually regrow from a...the Statement of Work Task 2, experimental radiation therapy has been designed and initiated based on the MRI oximetry data. Preliminary data of control...Hoechst dye 33342 showed a significant reduction in perfused vessels at 2hr after CA4P, which recovered 24 h later. * Experimental radiation therapy a

Oximetry: a reflective tool for the detection of physiological expression of emotions in a science education classroom

NASA Astrophysics Data System (ADS)

Calderón, Olga

2016-09-01

The pulse oximeter is a device that measures the oxygen concentration (or oxygen saturation—SpO2); heart rate, and heartbeat of a person at any given time. This instrument is commonly used in medical and aerospace fields to monitor physiological outputs of a patient according to health conditions or physiological yields of a flying pilot according to changes in altitude and oxygen availability in the atmosphere. Nonetheless, the uses for pulse oximetry may expand to other fields where there is human interaction and where physiological outputs reflect fluctuations mediated by arising emotions. A classroom, for instance is filled with a plethora of emotions, but very often participants in this space are unaware of others' or their own sentiments as these arise as a result of interactions and responses to class discussions. In this paper I describe part of a larger study-taking place at Brooklyn College of the City University of New York. The focus is on the exploration of emotions and mindfulness in the science classroom. The oximeter is used in this study as a reflexive tool to detect emotions emerging among participants of a graduate History and Philosophy of Science Education course offered in the spring of 2012. Important physiological information of class participants provided by the oximeter is used to analyze the role of emotions in the classroom as sensitive and controversial topics in science education are discussed every week.

In-vivo studies of reflectance pulse oximeter sensor

NASA Astrophysics Data System (ADS)

Ling, Jian; Takatani, Setsuo; Noon, George P.; Nose, Yukihiko

1993-08-01

Reflectance oximetry can offer an advantage of being applicable to any portion of the body. However, the major problem of reflectance oximetry is low pulsatile signal level which prevents prolonged clinical application during extreme situations, such as hypothermia and vasoconstriction. In order to improve the pulsatile signal level of reflectance pulse oximeter and thus its accuracy, three different sensors, with the separation distances (SPD) between light emitting diode (LED) and photodiode being 3, 5, and 7 mm respectively, were studied on nine healthy volunteers. With the increase of the SPD, it was found that both the red (660 nm) and near-infrared (830 nm) pulsatile to average signal ratio (AC/DC) increased, and the standard deviations of (AC/DC)red/(AC/DC)infrared ratio decreased, in spite of the decrease of the absolute signal level. Further clinical studies of 3 mm and 7 mm SPD sensors on seven patients also showed that the (AC/DC)red/(AC/DC)infrared ratio measured by the 7 mm sensor were less disturbed than the 3 mm sensor during the surgery. A theoretical study based on the three-dimensional photon diffusion theory supports the experimental and clinical results. As a conclusion, the 7 mm sensor has the highest signal-to- noise ratio among three different sensors. A new 7 mm SPD reflectance sensor, with the increased number of LEDs around the photodiode, was designed to increase the AC/DC ratio, as well as to increase the absolute signal level.

Oxygen Saturation in Closed-Globe Blunt Ocular Trauma

PubMed Central

Long, Chongde; Wen, Xin; Gao, Qianying

2016-01-01

Purpose. To evaluate the oxygen saturation in retinal blood vessels in patients after closed-globe blunt ocular trauma. Design. Retrospective observational case series. Methods. Retinal oximetry was performed in both eyes of 29 patients with unilateral closed-globe blunt ocular trauma. Arterial oxygen saturation (SaO2), venous oxygen saturation (SvO2), arteriovenous difference in oxygen saturation (SO2), arteriolar diameter, venular diameter, and arteriovenous difference in diameter were measured. Association parameters including age, finger pulse oximetry, systolic pressure, diastolic pressure, and heart rate were analyzed. Results. The mean SaO2 in traumatic eyes (98.1% ± 6.8%) was not significantly different from SaO2 in unaffected ones (95.3% ± 7.2%) (p = 0.136). Mean SvO2 in traumatic eyes (57.1% ± 10.6%) was significantly lower than in unaffected ones (62.3% ± 8.4%) (p = 0.044). The arteriovenous difference in SO2 in traumatic eyes (41.0% ± 11.2%) was significantly larger than in unaffected ones (33.0% ± 6.9%) (p = 0.002). No significant difference was observed between traumatic eyes and unaffected ones in arteriolar (p = 0.249) and venular diameter (p = 0.972) as well as arteriovenous difference in diameter (p = 0.275). Conclusions. Oxygen consumption is increased in eyes after cgBOT, associated with lower SvO2 and enlarged arteriovenous difference in SO2 but not with changes in diameter of retinal vessels. PMID:27699174

Cerebral Oximetry as an Auxiliary Diagnostic Tool in the Diagnosis of Brain Death.

PubMed

Tatli, O; Bekar, O; Imamoglu, M; Gonenc Cekic, O; Aygun, A; Eryigit, U; Karaca, Y; Sahin, A; Turkmen, S; Turedi, S

2017-10-01

To investigate the efficacy of cerebral oximetry (CO) as an auxiliary diagnostic tool in brain death (BD). This observational case-control study was performed on patients with suspected BD. Patients with diagnosis of BD confirmed by the brain death committee were enrolled as the BD group and other patients as the non-BD group. CO monitoring was performed at least 6 h, and cerebral tissue oxygen saturation (ScO 2 ) parameters were compared. Mean ScO 2 level in the BD group was lower than non-brain-dead patients: mean difference for right lobe = 6.48 (95% confidence interval [CI] 0.08-12.88) and for left lobe = 6.09 (95% CI -0.22-12.41). Maximum ScO 2 values in the BD group were significantly lower than the non-BD group: mean difference for right lobe = 8.20 (95% CI 1.64-14.77) and for left lobe = 9.54 (95% CI 3.06-16.03). The area under the curve for right lobe maximum ScO 2 was 0.69 (95% CI 0.55-0.81) and for left lobe was 0.72 (95% CI 0.58-0.84). Maximum ScO 2 in brain-dead patients at CO monitoring is significantly low. However, this cannot be used to differentiate brain-dead and non-brain-dead patients. CO monitoring is therefore not an appropriate auxiliary diagnostic tool for confirming BD. Copyright © 2017 Elsevier Inc. All rights reserved.

Optical Characterization of Tissue Phantoms Using a Silicon Integrated fdNIRS System on Chip.

PubMed

Sthalekar, Chirag C; Miao, Yun; Koomson, Valencia Joyner

2017-04-01

An interface circuit with signal processing and digitizing circuits for a high frequency, large area avalanche photodiode (APD) has been integrated in a 130 nm BiCMOS chip. The system enables the absolute oximetry of tissue using frequency domain Near Infrared Spectroscopy (fdNIRS). The system measures the light absorbed and scattered by the tissue by measuring the reduction in the amplitude of signal and phase shift introduced between the light source and detector which are placed a finite distance away from each other. The received 80 MHz RF signal is downconverted to a low frequency and amplified using a heterodyning scheme. The front-end transimpedance amplifier has a 3-level programmable gain that increases the dynamic range to 60 dB. The phase difference between an identical reference channel and the optical channel is measured with a 0.5° accuracy. The detectable current range is [Formula: see text] and with a 40 A/W reponsivity using the APD, power levels as low as 500 pW can be detected. Measurements of the absorption and reduced scattering coefficients of solid tissue phantoms using this system are compared with those using a commercial instrument with differences within 30%. Measurement of a milk based liquid tissue phantom show an increase in absorption coefficient with addition of black ink. The miniaturized circuit serves as an efficiently scalable system for multi-site detection for applications in neonatal cerebral oximetry and optical mammography.

Effect of regional cerebral oximetry to estimate neurologic prognostic outcomes in patients administered targeted temperature management.

PubMed

Sarıtaş, Aykut; Çinleti, Burcu Acar; Zincircioğlu, Çiler; Uzun, Uğur; Köse, Işıl; Şenoğlu, Nimet

2018-04-09

The aim of our study is to research the role and efficacy of cerebral oximetry in predicting neurologic prognosis when applied during TTM to patients experiencing coma after CA. This study was performed on surviving adult comatose patients after CA treated with TTM. The average scores of rSO 2 was measured at 6h intervals for the first 2days and once a day for the following 3days with a NIRS device during TTM. The CPC scale was used to define the neurologic outcomes of patients. We compared the correlations of rSO 2 values between good (CPC 1-2) and poor (CPC 3-5) neurologic outcomes in CA patients. There was no statistically significant difference identified between the prognosis groups in terms of rSO 2 , CPR durations, hemoglobin values and admission body temperature (p>0.05). When the variation in rSO 2 values over time is investigated, though there was no significant difference between the good and poor prognosis groups, it appeared to fall in the first 6h in both prognosis groups. The median NT-proBNP and lactate values were observed to be higher in the poor prognosis group. There is no significant correlation between rSO 2 values and neurologic outcomes. Multimodal monitoring methods may be useful and further studies with a larger patient population are necessary in this area. Copyright © 2018. Published by Elsevier Inc.

Predictors of At-Home Arterial Oxygen Desaturation Events in Ambulatory Surgical Patients.

PubMed

Biddle, Chuck; Elam, Charles; Lahaye, Laura; Kerr, Gordon; Chubb, Laura; Verhulst, Brad

2016-11-02

Little is known about the early recovery phase occurring at-home after anesthesia and surgery in ambulatory surgical patients. We studied quantitative oximetry and quality-of-life metrics in the first 48 hours after same-day orthopedic surgery examining the association between the recovery metrics and specific patient and procedural factors. We used the STOP-Bang score to quantify patient risk for obstructive sleep apnea in 50 adult patients at 2 centers using continuous portable oximetry and patient journaling. Parametric statistical procedures were used to assess relationships among patient and procedural factors and desaturation events. Higher STOP-Bang scores were predictive of the number and duration of desaturation events below mild and severe thresholds for arterial oxygen saturation during their first 48 hours after discharge from ambulatory surgery. Older patients and patients with higher BMI in particular were at an increased risk of mild and severe arterial oxygen desaturation. Using a home CPAP reduced the number of desaturation events. Of interest, taking opiate analgesics decreased the number of desaturation events. Given the absence of systematic research of early ambulatory anesthesia/surgery recovery at home and concerns of postoperative respiratory events, our results have clear implications for patient safety. Our results imply that screening based on noninvasive STOP-Bang scores may allow for suggestions for recovery from ambulatory surgery, such as encouraging patients with high scores to use home CPAP and aggressive education regarding use of opiates.

Image-guided optical measurement of blood oxygen saturation within capillary vessels (Conference Presentation)

NASA Astrophysics Data System (ADS)

Akons, Kfir; Zeidan, Adel; Yeheskely-Hayon, Daniella; Minai, Limor; Yelin, Dvir

2016-03-01

Values of blood oxygenation levels are useful for assessing heart and lung conditions, and are frequently monitored during routine patient care. Independent measurement of the oxygen saturation in capillary blood, which is significantly different from that of arterial blood, is important for diagnosing tissue hypoxia and for increasing the accuracy of existing techniques that measure arterial oxygen saturation. Here, we developed a simple, non-invasive technique for measuring the reflected spectra from individual capillary vessels within a human lip, allowing local measurement of the blood oxygen saturation. The optical setup includes a spatially incoherent broadband light that was focused onto a specific vessel below the lip surface. Backscattered light was imaged by a camera for identifying a target vessel and pointing the illumination beam to its cross section. Scattered light from the vessel was then collected by a single-mode fiber and analyzed by a fast spectrometer. Spectra acquired from small capillary vessels within a volunteer lip showed the characteristic oxyhemoglobin absorption bands in real time and with a high signal-to-noise ratio. Measuring capillary oxygen saturation using this technique would potentially be more accurate compared to existing pulse oximetry techniques due to its insensitivity to the patient's skin color, pulse rate, motion, and medical condition. It could be used as a standalone endoscopic technique for measuring tissue hypoxia or in conjunction with conventional pulse oximetry for a more accurate measurement of oxygen transport in the body.

Non-invasive carboxyhemoglobin monitoring: screening emergency medical services patients for carbon monoxide exposure.

PubMed

Nilson, Douglas; Partridge, Robert; Suner, Selim; Jay, Gregory

2010-01-01

Carbon monoxide (CO) toxicity is a significant health problem. The use of non-invasive pulse CO-oximetry screening in the emergency department has demonstrated that the rapid screening of numerous individuals for CO toxicity is simple and capable of identifying occult cases of CO toxicity. The objective of this study was to extend the use of this handheld device to the prehospital arena, assess carboxyhemoglobin (SpCO) levels in emergency medical services (EMS) patients, and correlate these levels with clinical and demographic data. This was a retrospective, observational, chart review of adult patients transported to hospital emergency departments by urban fire department EMS ambulances during a six-week period. Each ambulance used a non-invasive pulse CO-oximeter (Rad-57, Masimo Inc.) to record patients' COHb concentrations (SpCO) along with the standard EMS assessment data. Spearman's Rank Correlation tests and Student's t-tests were used to analyze the data and calculate relationships between SpCO and other variables (age, gender, respiratory rate, heart rate, mean arterial pressure, and oxygen saturation measured by pulse oximetry). A total of 36.4% of the patients transported during the study had SpCO documented. Of the 1,017 adults included in this group, 11 (1.1%) had an SpCO >15%. There was no correlation between SpCO and heart rate, ventilatory rate, mean arterial pressure, and oxygen saturation. Screening for CO toxicity in the EMS setting is possible, and may aid in the early detection and treatment of CO-poisoned patients.

Intraoperative pulse oximetry: frequency and distribution of discrepant data.

PubMed

Pan, P H; Gravenstein, N

1994-01-01

To determine the types of discrepant data during intraoperative pulse oximetry and their frequency and duration. Prospective study. University medical center. 46 consecutive ASA physical status I-III patients undergoing general anesthesia for elective surgical operations. With an integrated computer algorithm on the pulse oximeter and another computer linked to it, data were screened and the frequency and distribution of the following oximeter signals recorded: absent; low quality or interrupted, as detected by the pulse oximeter algorithm; nonphysiologic, identified by the personal computer as a heart rate change greater than 10 beats per minute within 2 consecutive 2-second samples, with no similar abrupt change reported simultaneously on ECG. The number of episodes per hour of discrepant oximeter data and the duration of the episodes were recorded by phase of anesthesia: induction, maintenance, and emergence. Discrepant data occurred most frequently and lasted longest during emergence (p < 0.05); the majority of episodes of discrepant data during emergence lasted less than 12 seconds. Excluding discrepant data that lasted less than 12 seconds decreased the frequency of discrepant data by 63% and excluding those that lasted less than 30 seconds decreased the frequency of discrepant data by 93%. Pulse oximeters frequently report discrepant data intraoperatively, most frequently during emergence from anesthesia. An alarm delay triggered by discrepant data and lasting 12 to 30 seconds would keep most discrepant data from becoming false alarms and, thus, may reduce distracting sound pollution in the operating room.

Correction method for influence of tissue scattering for sidestream dark-field oximetry using multicolor LEDs

NASA Astrophysics Data System (ADS)

Kurata, Tomohiro; Oda, Shigeto; Kawahira, Hiroshi; Haneishi, Hideaki

2016-12-01

We have previously proposed an estimation method of intravascular oxygen saturation (SO_2) from the images obtained by sidestream dark-field (SDF) imaging (we call it SDF oximetry) and we investigated its fundamental characteristics by Monte Carlo simulation. In this paper, we propose a correction method for scattering by the tissue and performed experiments with turbid phantoms as well as Monte Carlo simulation experiments to investigate the influence of the tissue scattering in the SDF imaging. In the estimation method, we used modified extinction coefficients of hemoglobin called average extinction coefficients (AECs) to correct the influence from the bandwidth of the illumination sources, the imaging camera characteristics, and the tissue scattering. We estimate the scattering coefficient of the tissue from the maximum slope of pixel value profile along a line perpendicular to the blood vessel running direction in an SDF image and correct AECs using the scattering coefficient. To evaluate the proposed method, we developed a trial SDF probe to obtain three-band images by switching multicolor light-emitting diodes and obtained the image of turbid phantoms comprised of agar powder, fat emulsion, and bovine blood-filled glass tubes. As a result, we found that the increase of scattering by the phantom body brought about the decrease of the AECs. The experimental results showed that the use of suitable values for AECs led to more accurate SO_2 estimation. We also confirmed the validity of the proposed correction method to improve the accuracy of the SO_2 estimation.

High prevalence of recurrent nocturnal desaturations in systemic AL amyloidosis: a cross-sectional pilot study.

PubMed

Mahmood, Shameem; Sovani, Milind; Smith, Peter; George, Leena; Quarta, Christina C; Sachchithanantham, Sajitha; Fontana, Marianna; Whelan, Carol J; Lachmann, Helen J; Gillmore, Julian D; Hawkins, Philip N; Wechalekar, Ashutosh D

2017-04-01

Cardiac involvement and/or macroglossia with soft tissue deposits are risk factors for central sleep apnoea (CSA) and obstructive sleep apnoea (OSA), and common features of systemic AL amyloidosis. Little data exist on the occurrence of sleep-disordered breathing (SDB) or recurrent nocturnal hypoxia in amyloidosis, which this study sought to investigate. A total of 72 consecutive patients with systemic amyloidosis (mean age 69 years and mean BMI 25) were evaluated for occurrence of SDB, by overnight continuous pulse oximetry, and completed Epworth Sleepiness Score (ESS) and STOPBANG questionnaires. Patients included: AL cardiac (AL-C), AL macroglossia (AL-M), AL both (AL-CM) and transthyretin (ATTR). Mean overnight oxygen saturations were 93% (SD ± 2, 95% CI 87-96) with abnormal oximetry (4% oxygen desaturation index (ODI) >5/hour): AC-C 84%, AL-M 57%, AL-CM 62% and ATTR 47%. NYHA class directly correlated with a higher 4% ODI, NYHA class I vs 3, (p = 0.01). Two-thirds of patients had STOPBANG scores >3 and abnormally high ESS scores (>10) were seen in up to 30% of patients. Recurrent nocturnal hypoxaemia, suggestive of sleep-disordered breathing, is frequent in systemic AL amyloidosis. The higher incidence in cardiac amyloidosis highlights CSA and recurrent hypoxia as possible mechanisms for morbidity/mortality in these cases. A detailed polysomnography study is planned to clarify and further investigate these findings. Copyright © 2016. Published by Elsevier B.V.

Optical surgical navigation system causes pulse oximeter malfunction.

PubMed

Satoh, Masaaki; Hara, Tetsuhito; Tamai, Kenji; Shiba, Juntaro; Hotta, Kunihisa; Takeuchi, Mamoru; Watanabe, Eiju

2015-01-01

An optical surgical navigation system is used as a navigator to facilitate surgical approaches, and pulse oximeters provide valuable information for anesthetic management. However, saw-tooth waves on the monitor of a pulse oximeter and the inability of the pulse oximeter to accurately record the saturation of a percutaneous artery were observed when a surgeon started an optical navigation system. The current case is thought to be the first report of this navigation system interfering with pulse oximetry. The causes of pulse jamming and how to manage an optical navigation system are discussed.

Effect of glucose on the optical properties of arterial blood using Mie theory simulations

NASA Astrophysics Data System (ADS)

Clancy, Neil T.; Leahy, Martin J.

2005-08-01

The glucose concentration in arterial plasma has immediate effects on the optical properties of blood-bearing tissue due primarily to the alteration of refractive index mismatch between the scattering particles (red blood cells) and the medium (plasma). The influence of these effects on pulse oximetry is investigated using a numerical model based on Mie theory. The objective is to determine whether or not physiological fluctuations in blood glucose levels could sufficiently vary the optical properties to shift the calibration curve of a commercial pulse oximeter significantly.

Estimation of Individual-specific Progression to Impending Cardiovascular Instability using Arterial Waveforms

DTIC Science & Technology

2013-08-08

pressure; SpO2, oxygen saturation of arterial blood by pulse oximetry. -75-60-45-30-15Baseline 40 50 60 70 80 90 100 HT LT LBNP, mmHg S tr o ke V o...systolic arterial blood pressure (mmHg) generated from the Finometer. R-R intervals (ms) were used to calculate heart rate (beats/min). Oxygen saturation of...The CRI can be integrated into any standard monitor that generates an arterial waveform, including a finger pulse oximeter that is available in the

Development and Evaluation of New Products for the Far-Forward Care of Combat Casualties with Acute Lung Injury

DTIC Science & Technology

2006-02-01

pulmonary artery wedge pressure (PAWP) were determined at each time point. Electrocardiogram (ECG), pulse oximetry ( SpO2 ) (Datex Ohmeda True Tech Plus...cm H2O positive end expiratory pressure (PEEP) and a goal for oxygenation of at least 90% by arterial 8 blood hemoglobin O2 saturation ( SpO2 and...or SaO2). The fraction of inspired O2 concentration was 21% and was adjusted as necessary to maintain SpO2 ≥ 90% and partial pressure of O2 in

How Should Oxygen Supplementation Be Guided by Pulse Oximetry in Children: Do We Know the Level?

PubMed Central

Langley, Ross; Cunningham, Steve

2017-01-01

Supplemental oxygen is one of the most commonly prescribed therapies to children in hospital, but one of the least studied therapeutics. This review considers oxygen from a range of perspectives; discovery and early use; estimation of oxygenation in the human body—both clinically and by medical device; the effects of illness on oxygen utilization; the cellular consequences of low oxygen; and finally, how clinical studies currently inform our approach to targeting supplementing oxygen in those with lower than normal oxygen saturation. PMID:28191454

Severe methemoglobinemia complicating topical benzocaine use during endoscopy in a toddler: a case report and review of the literature.

PubMed

Dahshan, Ahmed; Donovan, G Kevin

2006-04-01

Severe methemoglobinemia resulting from the use of topical benzocaine has been reported in adults as a rare complication. Here we report a case of severe acquired methemoglobinemia resulting from topical use of benzocaine spray during diagnostic upper gastrointestinal endoscopy in a 3-year-old boy with repeated episodes of hematemesis 3 weeks posttonsillectomy. He developed marked cyanosis and became increasingly agitated immediately after completion of his unremarkable endoscopic procedure, which was performed under intravenous sedation. He did not respond to maximum supplemental oxygen and had increased respiratory effort. His pulse oximetry dropped to 85%, but simultaneous arterial blood-gas analysis showed marked hypoxemia (Po2 = 29%) and severe methemoglobinemia (methemoglobin = 39%). His cyanosis and altered mental status promptly resolved after intravenous administration of methylene blue. In patients with methemoglobinemia, pulse oximetry tends to overestimate the actual oxygen saturation and is not entirely reliable. Posttonsillectomy bleeding is a rare but occasionally serious complication that could occur weeks after the surgery, although it more commonly occurs within the first few days. Physicians should remain aware of the possibility of its late onset. This case illustrates the severity of acquired methemoglobinemia that may result from even small doses of topical benzocaine and highlights the fact that prompt treatment of the disorder can be life saving. We question the rationale for routine use of topical anesthetic spray for sedated upper gastrointestinal endoscopy in children. By bringing the attention of pediatricians to this rare but serious complication, we hope that it will result in its improved recognition and possible prevention.

Hemodynamic and metabolic parameters during prolonged cardiac arrest and reperfusion by extracorporeal circulation.

PubMed

Mlček, M; Ošťádal, P; Bělohlávek, J; Havránek, Š; Hrachovina, M; Huptych, M; Hála, P; Hrachovina, V; Neužil, P; Kittnar, O

2012-01-01

Extracorporeal membranous oxygenation (ECMO) is increasingly used in the management of refractory cardiac arrest. Our aim was to investigate early effects of ECMO after prolonged cardiac arrest. In fully anesthetized swine (48 kg, N=18) ventricular fibrillation (VF) was induced and untreated period (20 min) of cardiac arrest commenced, followed by 60 min extracorporeal reperfusion (ECMO flow 100 ml/kg.min). Hemodynamics, arterial blood gasses, plasma potassium, tissue oximetry (StO(2)) and cardiac (EGM) and cerebral (BIS) electrophysiological parameters were continuously recorded and analyzed. Within 3 minutes of VF hemodynamic and oximetry parameters fall abruptly while metabolic parameters destabilize gradually over 20 minutes peaking at pH 7.04 ± 0.05, pCO(2) 89 ± 14 mmHg, K(+) 8.5 ± 1.6 mmol/l. During reperfusion most parameters restore rapidly: within 3-5 minutes mean arterial pressure reaches >40 mmHg, StO(2)>50 %, paO(2)>100 mmHg, pCO(2)<50 mmHg, K(+)<5 mmol/l. EGMs mean amplitude peaks at 4.5 ± 2.4 min. Cerebral activity (BIS>60) reappeared in 5 animals after 87 ± 21 min. In 12/18 animals return of spontaneous circulation was achieved. In conclusions, ECMO provides rapid restitution of internal milieu even after prolonged arrest. However, despite normalization of global parameters full recovery was not guaranteed since cardiac and cerebral electrical activities were sufficiently restored only in some animals. More sensitive and organ specific indicators need to be identified in order to estimate adequacy of cardiac support devices.

The effect of nail polish and acrylic nails on pulse oximetry reading using the Lifebox oximeter in Nigeria.

PubMed

Desalu, I; Diakparomre, O I; Salami, A O; Abiola, A O

2013-12-01

AIMS AND OBJECTIVES - Pulse oximetry is mandatory during anaesthesia, sedation and transfer of critically ill patients. The effect of nail polish and acrylic nails on the accuracy of saturation reading is inconsistent. The Lifebox pulse oximeter is reliable and recommended for low and middle income countries. We investigated its accuracy in the presence of 4 nail colours and acrylic nails SUBJECTS AND METHODS Fifty non-smoking volunteers had their fingers numbered from right to left (little finger of right hand =1 and little finger of left hand =10). Alternate fingers were nails painted with clear, red, brown and black nail polish and the 5th finger had acrylic nail applied. The corresponding finger on the other hand acted as control. The oxygen saturation was determined using the Lifebox pulse oximeter. Results All fingers (100%) with clear nail polish, red nail polish and acrylic nails recorded a saturation value. Each of the mean saturation value for clear nail polish, red nail polish and acrylic nails was not significantly different from the control mean (p= 0.378, 0.427 and 0.921). Only 12% and 64% of nails polished black and brown respectively recorded a saturation value. The mean SpO- for black and brown polish were significantly different from their control mean (p<0.001). CONCLUSION Black and brown polish resulted in a significant decrease in SpO with the Lifebox oximeter. Dark coloured nail polish should be removed prior to SpO2 determination to ensure that accurate readings can be obtained.

Visible light optical coherence tomography for microvascular oximetry in ocular circulation (Conference Presentation)

NASA Astrophysics Data System (ADS)

Chen, Siyu; Yi, Ji; Zhang, Hao F.

2016-03-01

Visible light optical coherence tomography (vis-OCT) is intrinsically capable of optical determination of blood oxygen saturation (sO2). Thanks to its 3D sectioning ability, confounding factors that plaque multi-wavelength fundus photography can be avoided. We further supplemented it with motion-enhanced angiography (vis-OCTA), which allowed us to resolve retinal micro vessels without losing spectral information. As a result, spectroscopic vis-OCTA can extract microvascular sO2 which are generally inaccessible. Here we extend the theoretical formulation of vis-OCTA oximetry to include optical attenuation, scattering and motion contrast. The model allows robust estimation of sO2, while also promising reduction of illuminating power to 1/3 of current value of ~1 mW. To demonstrate the capability of our approach, we performed oxygen challenge while taking vis-OCTA measurements on rat ocular circulation in vivo. We supplied the experiment animal with the following gas mixture: normal air, 5% CO2 air, pure O2 and 10% O2 air. For each inhalation gas, the OCTA measurements were compared with peripheral capillary sO2 (spO2) provided by a pulse oximeter. The retinal artery sO2 measurements corresponded well with spO2 reading as expected (R2 = 0.87). We found that both retinal and choroidal circulation sO2 moderately increased when we supplied 5% CO2 air. 100% O2 inhalation significantly increased both artery and vein oxygenation. On the contrary, 10% O2 air could deplete the oxygen reservoir in the circulation and lead to low sO2 readings.

Oxygen Desaturation Index Estimation through Unconstrained Cardiac Sympathetic Activity Assessment Using Three Ballistocardiographic Systems.

PubMed

Jung, Da Woon; Hwang, Su Hwan; Lee, Yu Jin; Jeong, Do-Un; Park, Kwang Suk

2016-01-01

Nocturnal hypoxemia, characterized by abnormally low oxygen saturation levels in arterial blood during sleep, is a significant feature of various pathological conditions. The oxygen desaturation index, commonly used to evaluate the nocturnal hypoxemia severity, is acquired using nocturnal pulse oximetry that requires the overnight wear of a pulse oximeter probe. This study aimed to suggest a method for the unconstrained estimation of the oxygen desaturation index. We hypothesized that the severity of nocturnal hypoxemia would be positively associated with cardiac sympathetic activation during sleep. Unconstrained heart rate variability monitoring was conducted using three different ballistocardiographic systems to assess cardiac sympathetic activity. Overnight polysomnographic and ballistocardiographic recording pairs were collected from the 20 non-nocturnal hypoxemia (oxygen desaturation index <5 events/h) subjects and the 76 nocturnal hypoxemia patients. Among the 96 recording pairs, 48 were used as training data and the remaining 48 as test data. The regression analysis, performed using the low-frequency component of heart rate variability, exhibited a root mean square error of 3.33 events/h between the estimates and the reference values of the oxygen desaturation index. The nocturnal hypoxemia diagnostic performance produced by our method was presented with an average accuracy of 96.5% at oxygen desaturation index cutoffs of ≥5, 15, and 30 events/h. Our method has the potential to serve as a complementary measure against the accidental slip-out of a pulse oximeter probe during nocturnal pulse oximetry. The independent application of our method could facilitate home-based long-term oxygen desaturation index monitoring. © 2016 S. Karger AG, Basel.

The influence of hyperthermia on intracranial pressure, cerebral oximetry and cerebral metabolism in traumatic brain injury

PubMed Central

Nyholm, Lena; Howells, Tim; Lewén, Anders; Hillered, Lars; Enblad, Per

2017-01-01

Background Hyperthermia is a common secondary insult in traumatic brain injury (TBI). The aim was to evaluate the relationship between hyperthermia and intracranial pressure (ICP), and if intracranial compliance and cerebral blood flow (CBF) pressure autoregulation affected that relationship. The relationships between hyperthermia and cerebral oximetry (BtipO2) and cerebral metabolism were also studied. Methods A computerized multimodality monitoring system was used for data collection at the neurointensive care unit. Demographic and monitoring data (temperature, ICP, blood pressure, microdialysis, BtipO2) were analyzed from 87 consecutive TBI patients. ICP amplitude was used as measure of compliance, and CBF pressure autoregulation status was calculated using collected blood pressure and ICP values. Mixed models and comparison between groups were used. Results The influence of hyperthermia on intracranial dynamics (ICP, brain energy metabolism, and BtipO2) was small, but individual differences were seen. Linear mixed models showed that hyperthermia raises ICP slightly more when temperature increases in the groups with low compliance and impaired CBF pressure autoregulation. There was also a tendency (not statistically significant) for increased BtipO2, and for increased pyruvate and lactate, with higher temperature, while the lactate/pyruvate ratio and glucose were stable. Conclusions The major finding was that the effects of hyperthermia on intracranial dynamics (ICP, brain energy metabolism, and BtipO2) were not extensive in general, but there were exceptional cases. Hyperthermia treatment has many side effects, so it is desirable to identify cases in which hyperthermia is dangerous. Information from multimodality monitoring may be used to guide treatment in individual patients. PMID:28463046

High or low oxygen saturation and severe retinopathy of prematurity: a meta-analysis.

PubMed

Chen, Minghua L; Guo, Lei; Smith, Lois E H; Dammann, Christiane E L; Dammann, Olaf

2010-06-01

Low oxygen saturation appears to decrease the risk of severe retinopathy of prematurity (ROP) in preterm newborns when administered during the first few weeks after birth. High oxygen saturation seems to reduce the risk at later postmenstrual ages (PMAs). However, previous clinical studies are not conclusive individually. To perform a systematic review and meta-analysis to report the association between severe ROP incidence of premature infants with high or low target oxygen saturation measured by pulse oximetry. Studies were identified through PubMed and Embase literature searches through May 2009 by using the terms "retinopathy of prematurity and oxygen" or "retinopathy of prematurity and oxygen therapy." We selected 10 publications addressing the association between severe ROP and target oxygen saturation measured by pulse oximetry. Using a random-effects model we calculated the summary-effect estimate. We visually inspected funnel plots to examine possible publication bias. Low oxygen saturation (70%-96%) in the first several postnatal weeks was associated with a reduced risk of severe ROP (risk ratio [RR]: 0.48 [95% confidence interval (CI): 0.31-0.75]). High oxygen saturation (94%-99%) at > or = 32 weeks' PMA was associated with a decreased risk for progression to severe ROP (RR: 0.54 [95% CI: 0.35-0.82]). Among preterm infants with a gestational age of < or = 32 weeks, early low and late high oxygen saturation were associated with a reduced risk for severe ROP. We feel that a large randomized clinical trial with long-term developmental follow-up is warranted to confirm this meta-analytic result.

Measurement of differences in pO2 in response to perfluorocarbon/carbogen in FSa and NFSa murine fibrosarcomas with low-frequency electron paramagnetic resonance oximetry.

PubMed

Halpern, H J; Yu, C; Peric, M; Barth, E D; Karczmar, G S; River, J N; Grdina, D J; Teicher, B A

1996-05-01

We have used very low-frequency electron paramagnetic resonance (EPR) oximetry to measure the change in oxygen concentration (delta pO2) due to change in breathing atmosphere in FSa and NFSa fibrosarcomas implanted in the legs of C3H mice infused with perfluoro-octylbromine (PFOB). Measurements in each tumor were made before and after the administration of the high-density (47% v/v) perfluorocarbon PFOB, perflubron (Alliance Pharmaceutical Corporation, San Diego, CA). Measurements in each tumor were also made, after the administration of the PFOB, both before (PFOB/air) and after the administration of carbogen (95% O2 + 5% CO2, PFOB/carbogen). Large changes (delta p02) relative to PFOB/air oxygenation were seen with the administration of PFOB/carbogen. No significant difference in oxygen concentration was seen between air-breathing mice with and without PFOB. The mean delta pO2 for FSa tumors was 13 +/- 6 torr, while the mean for NFSa fibrosarcomas was 28 +/- 7 torr. There were such large intertumor differences that the trend toward a smaller change in the more hypoxic FSa tumors was not significant (P = 0.13). This paper describes a novel method of measuring differences in oxygenation in tumor tissues. The results of such measurements indicate large differences in pO2 response to different breathing atmospheres in PFOB-infused tumors of similar histology. The intertumor delta pO2 differences may correlate with differences in radiation response.

Using Medical-Device Wearable to Improve Hemodialysis Patient’s Live and Access the Holistic Health

NASA Astrophysics Data System (ADS)

Chen, W. L.; Wu, C.-C.; Kan, C. D.

2017-06-01

The increasing incidence of end-stage renal disease (ESRD) is the major burden to health budgets and a threat to public health worldwide. For many years, Taiwan has been ranked the first in the world for the number of hemodialysis patients. For solving the above-mentioned circumstance, we demonstrate the project, here, which goal is to construct the holistic health for hemodialysis patient. The project is to design a wearable medicine-device which can simultaneously measure and monitor the vital sign, including heart rate (HR), pulse oximetry (SPO2), continuous non-invasive blood pressure (c-NIBP), and total body water (TBW), of hemodialysis patient. By aid of the device we design, hemodialysis patients will get better health care than before. This device comprises three techniques. The first is named “Using phonoangiography technique to early detect the dysfunction of arteriovenous access by arteriovenous access (AVA) stenosis detector”. The stenosis detector based on autoregressive model was employed to simultaneously estimate the status of AVA life cycle and to tract changes in frequency spectra. It helps hemodialysis patients to early detect the dysfunction of AVA and alarms them to make a return visit. The second technique is named “Physiological detecting device for wearable medical device and encoding algorithm development”. The feature of the second technique is to optimize the prognosis by analyzing physiological signals, including water content index, pulse oximetry, and blood pressure in the meanwhile. The third technique is named “Intelligent and smart tourniquet”. This technique aims to preclude AVA dysfunction caused by inappropriate hemostasis.

Continuous monitoring of haemoglobin concentration after in-vivo adjustment in patients undergoing surgery with blood loss.

PubMed

Frasca, D; Mounios, H; Giraud, B; Boisson, M; Debaene, B; Mimoz, O

2015-07-01

Non-invasive monitoring of haemoglobin concentration provides real-time measurement of haemoglobin concentration (SpHb) using multi-wavelength pulse co-oximetry. We hypothesised that in-vivo adjustment using the mean of three haemoglobinometer (HemoCue®) measurements from an arterial blood sample at the first SpHb measurement (HCueART) would increase the accuracy of the monitor. The study included 41 adults for a total of 173 measurements of haemoglobin concentration. In-vivo adjusted SpHb was automatically calculated by the following formula: in-vivo adjusted SpHb = unadjusted SpHb - (SpHb - HCueART). The accuracy of in-vivo adjusted SpHb was compared with SpHb retrospectively adjusted using the same formula, except for haemoglobin level which was assessed at the central laboratory and then compared with all other available invasive methods of haemoglobin measurement (co-oximetry, HbSAT; arterial HemoCue, HCueART; capillary HemoCue, HCueCAP). Compared with laboratory measurement of haemoglobin concentration, bias (precision) for unadjusted SpHb, in-vivo adjusted SpHb, retrospectively adjusted SpHb, HbSAT, HCueART and HCueCAP were -0.4 (1.4), -0.3 (1.1), -0.3 (1.1), -0.6 (0.7), 0.0 (0.4) and -0.5 (1.2) g.dl(-1) , respectively. In-vivo adjustment of SpHb values using the mean of three arterial HemoCue measurements improved the accuracy of the device similar to those observed after a retrospective adjustment using central laboratory haemoglobin level. © 2015 The Association of Anaesthetists of Great Britain and Ireland.

Ability of the Masimo pulse CO-Oximeter to detect changes in hemoglobin.

PubMed

Colquhoun, Douglas A; Forkin, Katherine T; Durieux, Marcel E; Thiele, Robert H

2012-04-01

The decision to administer blood products is complex and multifactorial. Accurate assessment of the concentration of hemoglobin [Hgb] is a key component of this evaluation. Recently a noninvasive method of continuously measuring hemoglobin (SpHb) has become available with multi-wavelength Pulse CO-Oximetry. The accuracy of this device is well documented, but the trending ability of this monitor has not been previously described. Twenty patients undergoing major thoracic and lumbar spine surgery were recruited. All patients received radial arterial lines. On the contralateral index finger, a R1 25 sensor (Rev E) was applied and connected to a Radical-7 Pulse CO-Oximeter (both Masimo Corp, Irvine, CA). Blood samples were drawn intermittently at the anesthesia provider's discretion and were analyzed by the operating room satellite laboratory CO-Oximeter. The value of Hgb and SpHb at that time point was compared. Trend analysis was performed by the four quadrant plot technique, testing directionality of change, and Critchley's polar plot method testing both directionality and magnitude of the change in values. Eighty-eight samples recorded at times of sufficient signal quality were available for analysis. Four quadrant plot analysis revealed 94% of data within the quadrants associated with the correct direction change, and 90% of data points lay within the analysis bounds proposed by Critchley. Pulse CO-Oximetry offers an acceptable trend monitor in patients undergoing major spine surgery. Future work should explore the ability of this device to detect large changes in hemoglobin, as well as its applicability in additional surgical and non-surgical patient populations.

Risk factors for anaesthetic-related death in cats: results from the confidential enquiry into perioperative small animal fatalities (CEPSAF).

PubMed

Brodbelt, D C; Pfeiffer, D U; Young, L E; Wood, J L N

2007-11-01

Cats are commonly anaesthetized in veterinary practice, but recent figures describing the frequency of or risk factors for anaesthetic-related death are not available. The aims of this study were to address these deficiencies. A nested case-control study was undertaken in 117 UK veterinary centres. All anaesthetic and sedation procedures and anaesthetic and sedation-related deaths (i.e. 'cases') occurring within 48 h were recorded. Details of patient, procedure, and perioperative management were recorded for all cases and randomly selected non-deaths (controls). A detailed statistical model of factors associated with anaesthetic and sedation-related death was constructed. Between June 2002 and June 2004, 175 deaths were classified as anaesthetic and sedation-related and 14 additional deaths (with insufficient information to be excluded) were included for the estimation of risk. During the study, 79 178 anaesthetic and sedation procedures were recorded and the overall risk of anaesthetic and sedation-related death was 0.24% (95% CI 0.20-0.27). Factors associated with increased odds of anaesthetic-related death were poor health status (ASA physical status classification), increasing age, extremes of weight, increasing procedural urgency and complexity, endotracheal intubation, and fluid therapy. Pulse monitoring and pulse oximetry were associated with reduced odds. The risk of anaesthetic-related death in cats appears to have decreased since the last published study in the UK. The results should aid the preoperative identification of cats at greatest risk. Greater care with endotracheal intubation and fluid administration are recommended, and pulse and pulse oximetry monitoring should be routinely implemented in cats.

Oxygen Therapy in the Delivery Room: What Is the Right Dose?

PubMed

Kapadia, Vishal; Wyckoff, Myra H

2018-06-01

Oxygen is the most commonly used medicine used during neonatal resuscitation in the delivery room. Oxygen therapy in delivery room should be used judiciously to avoid oxygen toxicity while delivering sufficient oxygen to prevent hypoxia. Measurement of appropriate oxygenation relies on pulse oximetry, but adequate ventilation and perfusion are equally important for oxygen delivery. In this article, we review oxygenation while transitioning from fetal to neonatal life, the importance of appropriate oxygen therapy, its measurement in the delivery room, and current recommendations for oxygen therapy and its limitations. Copyright © 2018 Elsevier Inc. All rights reserved.

Use of an evidence-based protocol to screen for sleep-disordered breathing in a heart failure disease management clinic.

PubMed

Garner, Shelby L; Traverse, Ramona D

2014-01-01

Undiagnosed and untreated sleep-disordered breathing can lead to negative health outcomes and increased utilization of health resources among patients with heart failure. The purpose of this evidence-based practice project was to implement and evaluate a new multifaceted sleep-disordered breathing screening protocol in a heart failure disease management clinic. The combined use of a symptoms questionnaire, the Epworth sleepiness scale, and overnight pulse oximetry was significantly more effective in identifying patients with a positive diagnosis of sleep-disordered breathing than using the Epworth sleepiness scale alone (P < .05).

[Labor monitoring in high-risk situations].

PubMed

Houfflin-Debarge, V; Closset, E; Deruelle, P

2008-02-01

Intrapartum asphyxia is increased in several situations such as intrauterine growth retardation, preterm labor, postdate pregnancy or maternal diabetes. In all these cases, fetal heart rate monitoring should be preferred to intermittent auscultation. Fetal scalp blood pH or lactates can be used to identify fetuses at risk of intrapartum asphyxia. However, fetal scalp blood sampling should not delay delivery in case of severe abnormal fetal heart rate as fetal asphyxia could occur rapidly in theses high-risk pregnancies. Data is insufficient to recommend fetal pulse oximetry or ECG analysis. Research should be undertaken to evaluate their performance in these situations.

Obstructive sleep apnea devices for out-of-center (OOC) testing: technology evaluation.

PubMed

Collop, Nancy A; Tracy, Sharon L; Kapur, Vishesh; Mehra, Reena; Kuhlmann, David; Fleishman, Sam A; Ojile, Joseph M

2011-10-15

Guidance is needed to help clinicians decide which out-of-center (OOC) testing devices are appropriate for diagnosing obstructive sleep apnea (OSA). A new classification system that details the type of signals measured by these devices is presented. This proposed system categorizes OOC devices based on measurements of Sleep, Cardiovascular, Oximetry, Position, Effort, and Respiratory (SCOPER) parameters.Criteria for evaluating the devices are also presented, which were generated from chosen pre-test and post-test probabilities. These criteria state that in patients with a high pretest probability of having OSA, the OOC testing device has a positive likelihood ratio (LR+) of 5 or greater coinciding with an in-lab-polysomnography (PSG)-generated apnea hypopnea index (AHI) ≥ 5, and an adequate sensitivity (at least 0.825).Since oximetry is a mandatory signal for scoring AHI using PSG, devices that do not incorporate oximetry were excluded. English peer-reviewed literature on FDA-approved devices utilizing more than 1 signal was reviewed according to the above criteria for 6 questions. These questions specifically addressed the adequacy of different respiratory and effort sensors and combinations thereof to diagnose OSA. In summary, the literature is currently inadequate to state with confidence that a thermistor alone without any effort sensor is adequate to diagnose OSA; if a thermal sensing device is used as the only measure of respiration, 2 effort belts are required as part of the montage and piezoelectric belts are acceptable in this context; nasal pressure can be an adequate measurement of respiration with no effort measure with the caveat that this may be device specific; nasal pressure may be used in combination with either 2 piezoelectric or respiratory inductance plethysmographic (RIP) belts (but not 1 piezoelectric belt); and there is insufficient evidence to state that both nasal pressure and thermistor are required to adequately diagnose OSA. With respect to alternative devices for diagnosing OSA, the data indicate that peripheral arterial tonometry (PAT) devices are adequate for the proposed use; the device based on cardiac signals shows promise, but more study is required as it has not been tested in the home setting; for the device based on end-tidal CO(2) (ETCO(2)), it appears to be adequate for a hospital population; and for devices utilizing acoustic signals, the data are insufficient to determine whether the use of acoustic signals with other signals as a substitute for airflow is adequate to diagnose OSA.Standardized research is needed on OOC devices that report LR+ at the appropriate AHI (≥ 5) and scored according to the recommended definitions, while using appropriate research reporting and methodology to minimize bias.

3-lead electrocardiogram is more reliable than pulse oximetry to detect bradycardia during stabilisation at birth of very preterm infants.

PubMed

Iglesias, Beatriz; Rodrí Guez, Marí A José; Aleo, Esther; Criado, Enrique; Martí Nez-Orgado, Jose; Arruza, Luis

2018-05-01

Current neonatal resuscitation guidelines suggest the use of ECG in the delivery room (DR) to assess heart rate (HR). However, reliability of ECG compared with pulse oximetry (PO) in a situation of bradycardia has not been specifically investigated. The objective of the present study was to compare HR monitoring using ECG or PO in a situation of bradycardia (HR <100 beats per minute (bpm)) during preterm stabilisation in the DR. Video recordings of resuscitations of infants <32 weeks of gestation were reviewed. HR readings in a situation of bradycardia (<100 bpm) at any moment during stabilisation were registered with both devices every 5 s from birth. A total of 29 episodes of bradycardia registered by the ECG in 39 video recordings were included in the analysis (n=29). PO did not detect the start of these events in 20 cases (69%). PO detected the start and the end of bradycardia later than the ECG (median (IQR): 5 s (0-10) and 5 s (0-7.5), respectively). A decline in PO accuracy was observed as bradycardia progressed so that by the end of the episode PO offered significantly lower HR readings than ECG. PO detects the start and recovery of bradycardia events slower and less accurately than ECG during stabilisation at birth of very preterm infants. ECG use in this scenario may contribute to an earlier initiation of resuscitation manoeuvres and to avoid unnecessary prolongation of resuscitation efforts after recovery. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Non-invasive evaluation of blood oxygen saturation and hematocrit from T1 and T2 relaxation times: In-vitro validation in fetal blood.

PubMed

Portnoy, Sharon; Seed, Mike; Sled, John G; Macgowan, Christopher K

2017-12-01

We propose an analytical method for calculating blood hematocrit (Hct) and oxygen saturation (sO 2 ) from measurements of its T 1 and T 2 relaxation times. Through algebraic substitution, established two-compartment relationships describing R1=T1-1 and R2=T2-1 as a function of hematocrit and oxygen saturation were rearranged to solve for Hct and sO 2 in terms of R 1 and R 2 . Resulting solutions for Hct and sO 2 are the roots of cubic polynomials. Feasibility of the method was established by comparison of Hct and sO 2 estimates obtained from relaxometry measurements (at 1.5 Tesla) in cord blood specimens to ground-truth values obtained by blood gas analysis. Monte Carlo simulations were also conducted to assess the effect of T 1 , T 2 measurement uncertainty on precision of Hct and sO 2 estimates. Good agreement was observed between estimated and ground-truth blood properties (bias = 0.01; 95% limits of agreement = ±0.13 for Hct and sO 2 ). Considering the combined effects of biological variability and random measurement noise, we estimate a typical uncertainty of ±0.1 for Hct, sO 2 estimates. Results demonstrate accurate quantification of Hct and sO 2 from T 1 and T 2 . This method is applicable to noninvasive fetal vessel oximetry-an application where existing oximetry devices are unusable or require risky blood-sampling procedures. Magn Reson Med 78:2352-2359, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Healthcare-associated pneumonia with positive respiratory methicillin-resistant Staphylococcus aureus culture: Predictors of the true pathogenicity.

PubMed

Enomoto, Yasunori; Yokomura, Koshi; Hasegawa, Hirotsugu; Ozawa, Yuichi; Matsui, Takashi; Suda, Takafumi

2017-03-01

Although methicillin-resistant Staphylococcus aureus (MRSA) is commonly isolated from respiratory specimens in healthcare-associated pneumonia (HCAP), it is difficult to determine the causative pathogen because of the possibilities of contamination/colonization. The present study aimed to identify clinical predictors of the true pathogenicity of MRSA in HCAP. Patients with HCAP with positive MRSA cultures in the sputum or endotracheal aspirates who were admitted to Seirei Mikatahara General Hospital, Hamamatsu, Japan, from 2009 to 2014 were enrolled. According to the administered drugs and the treatment outcomes, patients with true MRSA pneumonia (MP) and those with contamination/colonization of MRSA (false MP) were identified. Baseline characteristics were compared between groups, and clinical predictors of true MP were evaluated by logistic regression analyses. A total of 93 patients (mean age 78.7 ± 12.6 years) were identified and classified into the true MP (n = 16) or false MP (n = 77) groups. Although baseline characteristics were broadly similar between groups, the true MP group had significantly more patients with PaO 2  ≤ 60 Torr/pulse oximetry saturation ≤90% and those with MRSA single cultivation. Both variables were significant predictors of true MP in multivariate analysis (odds ratio of PaO 2  ≤ 60 Torr/pulse oximetry saturation ≤90%: 5.64, 95% confidence interval 1.17-27.32; odds ratio of MRSA single cultivation: 4.76, 95% confidence interval 1.22-18.60). Poor oxygenation and MRSA single cultivation imply the true pathogenicity of MRSA in HCAP with positive respiratory MRSA cultures. The present results might be helpful for the proper use of anti-MRSA drugs in this population. Geriatr Gerontol Int 2017; 17: 456-462. © 2016 Japan Geriatrics Society.

Reduction of motion artifact in pulse oximetry by smoothed pseudo Wigner-Ville distribution

PubMed Central

Yan, Yong-sheng; Poon, Carmen CY; Zhang, Yuan-ting

2005-01-01

Background The pulse oximeter, a medical device capable of measuring blood oxygen saturation (SpO2), has been shown to be a valuable device for monitoring patients in critical conditions. In order to incorporate the technique into a wearable device which can be used in ambulatory settings, the influence of motion artifacts on the estimated SpO2 must be reduced. This study investigates the use of the smoothed psuedo Wigner-Ville distribution (SPWVD) for the reduction of motion artifacts affecting pulse oximetry. Methods The SPWVD approach is compared with two techniques currently used in this field, i.e. the weighted moving average (WMA) and the fast Fourier transform (FFT) approaches. SpO2 and pulse rate were estimated from a photoplethysmographic (PPG) signal recorded when subject is in a resting position as well as in the act of performing four types of motions: horizontal and vertical movements of the hand, and bending and pressing motions of the finger. For each condition, 24 sets of PPG signals collected from 6 subjects, each of 30 seconds, were studied with reference to the PPG signal recorded simultaneously from the subject's other hand, which was stationary at all times. Results and Discussion The SPWVD approach shows significant improvement (p < 0.05), as compared to traditional approaches, when subjects bend their finger or press their finger against the sensor. In addition, the SPWVD approach also reduces the mean absolute pulse rate error significantly (p < 0.05) from 16.4 bpm and 11.2 bpm for the WMA and FFT approaches, respectively, to 5.62 bpm. Conclusion The results suggested that the SPWVD approach could potentially be used to reduce motion artifact on wearable pulse oximeters. PMID:15737241

Results From the New Jersey Statewide Critical Congenital Heart Defects Screening Program

PubMed Central

Garg, Lorraine F.; Van Naarden Braun, Kim; Knapp, Mary M.; Anderson, Terry M.; Koppel, Robert I.; Hirsch, Daniel; Beres, Leslie M.; Hyg, MS; Sweatlock, Joseph; Olney, Richard S.; Glidewell, Jill; Hinton, Cynthia F.; Kemper, Alex R.

2015-01-01

BACKGROUND AND OBJECTIVE New Jersey was the first state to implement legislatively mandated newborn pulse oximetry screening (POxS) in all licensed birthing facilities to detect critical congenital heart defects (CCHDs). The objective of this report was to evaluate implementation of New Jersey’s statewide POxS mandate. METHODS A 2-pronged approach was used to collect data on infants screened in all New Jersey birthing facilities from August 31, 2011, through May 31, 2012. Aggregate screening results were submitted by each birthing facility. Data on failed screens and clinical characteristics of those newborns were reported to the New Jersey Birth Defects Registry (NJBDR). Three indicators were used to distinguish the added value of mandated POxS from standard clinical care: prenatal congenital heart defect diagnosis, cardiology consultation or echocardiogram indicated or performed before PoxS, or clinical findings at the time of POxS warranting a pulse oximetry measurement. RESULTS Of 75 324 live births in licensed New Jersey birthing facilities, 73 320 were eligible for screening, of which 99% were screened. Forty-nine infants with failed POxS were reported to the NJBDR, 30 of whom had diagnostic evaluations solely attributable to the mandated screening. Three of the 30 infants had previously unsuspected CCHDs and 17 had other diagnoses or non-CCHD echocardiogram findings. CONCLUSIONS In the first 9 months after implementation, New Jersey achieved a high statewide screening rate and established surveillance mechanisms to evaluate the unique contribution of POxS. The screening mandate identified 3 infants with previously unsuspected CCHDs that otherwise might have resulted in significant morbidity and mortality and also identified other significant secondary targets such as sepsis and pneumonia. PMID:23858425

In vivo evidence of methamphetamine induced attenuation of brain tissue oxygenation as measured by EPR oximetry

PubMed Central

Weaver, John; Yang, Yirong; Purvis, Rebecca; Weatherwax, Theodore; Rosen, Gerald M.; Liu, Ke Jian

2014-01-01

Abuse of methamphetamine (METH) is a major and significant societal problem in the US, as a number of studies have suggested that METH is associated with increased cerebrovascular events, hemorrhage or vasospasm. Although cellular and molecular mechanisms involved in METH-induced toxicity are not completely understood, changes in brain O2 may play an important role and contribute to METH-induced neurotoxicity including dopaminergic receptor degradation. Given that O2 is the terminal electron acceptor for many enzymes that are important in brain function, the impact of METH on brain tissue pO2 in vivo remains largely uncharacterized. This study investigated striatal tissue pO2 changes in male C57BL/6 mice (16–20g) following METH administration using EPR oximetry, a highly sensitive modality to measure pO2 in vivo, in situ and in real time. We demonstrate that 20 min after a single injection of METH (8 mg/kg i.v.), the striatal pO2 was reduced to 81% of the pretreatment level and exposure to METH for 3 consecutive days further attenuated striatal pO2 to 64%. More importantly, pO2 did not recover fully to control levels even 24 hrs after administration of a single dose of METH. and continual exposure to METH exacerbates the condition. We also show a reduction in cerebral blood flow associated with a decreased brain pO2 indicating an ischemic condition. Our findings suggests that administration of METH can attenuate brain tissue pO2, which may lead to hypoxic insult, thus a risk factor for METH-induced brain injury and the development of stroke in young adults. PMID:24412707

Where do pulse oximeter probes break?

PubMed

Crede, S; Van der Merwe, G; Hutchinson, J; Woods, D; Karlen, W; Lawn, J

2014-06-01

Pulse oximetry, a non-invasive method for accurate assessment of blood oxygen saturation (SPO2), is an important monitoring tool in health care facilities. However, it is often not available in many low-resource settings, due to expense, overly sophisticated design, a lack of organised procurement systems and inadequate medical device management and maintenance structures. Furthermore medical devices are often fragile and not designed to withstand the conditions of low-resource settings. In order to design a probe, better suited to the needs of health care facilities in low-resource settings this study aimed to document the site and nature of pulse oximeter probe breakages in a range of different probe designs in a low to middle income country. A retrospective review of job cards relating to the assessment and repair of damaged or faulty pulse oximeter probes was conducted at a medical device repair company based in Cape Town, South Africa, specializing in pulse oximeter probe repairs. 1,840 job cards relating to the assessment and repair of pulse oximeter probes were reviewed. 60.2 % of probes sent for assessment were finger-clip probes. For all probes, excluding the neonatal wrap probes, the most common point of failure was the probe wiring (>50 %). The neonatal wrap most commonly failed at the strap (51.5 %). The total cost for quoting on the broken pulse oximeter probes and for the subsequent repair of devices, excluding replacement components, amounted to an estimated ZAR 738,810 (USD $98,508). Improving the probe wiring would increase the life span of pulse oximeter probes. Increasing the life span of probes will make pulse oximetry more affordable and accessible. This is of high priority in low-resource settings where frequent repair or replacement of probes is unaffordable or impossible.

[Pulse oximetry versus electrocardiogram for heart rate assessment during resuscitation of the preterm infant].

PubMed

Iglesias, B; Rodríguez, M J; Aleo, E; Criado, E; Herranz, G; Moro, M; Martínez Orgado, J; Arruza, L

2016-05-01

Heart rate (HR) assessment is essential during neonatal resuscitation, and it is usually done by auscultation or pulse oximetry (PO). The aim of the present study was to determine whether HR assessment with ECG is as fast and reliable as PO during preterm resuscitation. Thirty-nine preterm (<32 weeks of gestational age and/or<1.500g of birth weight) newborn resuscitations were video-recorded. Simultaneous determinations of HR using ECG and PO were registered every 5s for the first 10min after birth. Time needed to place both devices and to obtain reliable readings, as well as total time of signal loss was registered. The proportion of reliable HR readings available at the beginning of different resuscitation manoeuvres was also determined. Time needed to connect the ECG was shorter compared with the PO (26.64±3.01 vs. 17.10±1.28 s, for PO and ECG, respectively, P<.05). Similarly, time to obtain reliable readings was shorter for the ECG (87.28±12.11 vs. 26.38±3.41 s, for PO and ECG, respectively, P<.05). Availability of reliable HR readings at initiation of different resuscitation manoeuvres was lower with the PO (PO vs. ECG for positive pressure ventilation: 10.52 vs. 57.89% P<.05; intubation: 33.33 vs. 91.66%, P<.05). PO displayed lower HR values during the first 6min after birth (P<.05, between 150 and 300s). Reliable HR is obtained later with the PO than with the ECG during preterm resuscitation. PO underestimates HR in the first minutes of resuscitation. Copyright © 2015 Asociación Española de Pediatría. Published by Elsevier España, S.L.U. All rights reserved.

The Predictive Value of Pulse Oximeters for Pulse Improvement after Angiography in Infants and Children

PubMed Central

Alipour, Mohammad-Reza; Rastegar, Mazyar; Ghaderian, Mehdi; Namayandeh, Seyedeh-Mahdieh; Faraji, Reza; Pezeshkpour, Zohreh

2016-01-01

Background Information from pulse oximeter waves confirms the presence of a pulse and helps obtain waves from tissue when the supplying artery is not readily accessible. Objectives This study determined the predictive value of pulse oximeters for detecting improved arterial pulses after angiography. Patients and Methods This cross-sectional, multi-center study included 467 4-day-old to 12-year-old patients and was conducted from January 2012 to January 2016. Angiographies were performed on 12-year-old or younger children for various medical reasons using venous, arterial, or both types of paths. The posterior malleolar or dorsalis pedis were palpated in punctured lower extremities. In the absence of a pulse, pulse oximetry was performed to identify pulse curves at 1 hour, 6 hours, and 12 hours after each angiography. Results Pulse oximetry displayed the pulses of 319 patients immediately following each angiography. Of these, 262 patients had palpable pulses at 6 hours after angiography (P < 0.0001), while 57 patients had no palpable pulse. Of these 57 patients, 15 had no palpable pulse at 12 hours after angiography (P < 0.0001). The odds of pulse improvement in children 6 hours after catheter angiography were 76% for the arterial path, 90% for the venous path, and 83.2% for both paths. At 12 hours after catheter angiography, these values increased to 91.6% for the arterial path, 100% for the venous path, and 95.9% for both paths. Conclusions The pulse oximeter can display the pulse curve immediately (1 hour) after angiography and indicate pulse improvement at 12 hours maximally following an angiography. In this case, heparin alone may be used instead of thrombolytic agents. PMID:28203338

Comparison of two new generation pulse oximeters with arterial oxygen saturation in critically ill children.

PubMed

Jose, Bipin; Lodha, Rakesh; Kabra, S K

2014-12-01

To compare the performance of two new generation pulse oximeters, one with enhanced signal extraction technology (SET) and other without enhanced SET in detecting hypoxemia and to correlate it with arterial blood gas analysis. Forty-eight patients, admitted to pediatric intensive care unit (PICU) of a teritiary care teaching hospital in India for critical care and support during the study period, who had an arterial catheter in situ were included. Children with those disease conditions known to interfere with pulse oximetry and blood gas analysis were excluded.184 set of observations were made during the study period. Each set had oxygen saturation (SpO2) measured from both the pulse oximeters and the corresponding arterial oxygen saturation (SaO2). The values were compared for occurrence of true and false alarms during periods of normal BP, hypotension and varying degrees of hypoxia. The mean arterial SaO2 in the study was 94.4 % ± 4.9. The mean SpO2 recorded in conventional and enhanced signal extraction technology (SET) pulse oximeters were 94.9 % ± 4.5 and 97.2 % ± 4.7 respectively. Enhanced signal extraction technology pulse oximeter detected 4/27 (15 %) of true hypoxemic events and 1 event was a false alarm. Conventional pulse oximeter detected 11/27 (41 %) true hypoxemic events but recorded 6 false alarms. Both pulse oximeters were not found to be performing satisfactorily in picking up hypoxemia in the study. There was good correlation with mean SpO2 from pulse oximeters and arterial SaO2. The reliability of pulse oximetry decreases with worsening hypoxemia and hypotension, and the sensitivity for picking up hypoxemia can be as low as 15 %.

Dark skin decreases the accuracy of pulse oximeters at low oxygen saturation: the effects of oximeter probe type and gender.

PubMed

Feiner, John R; Severinghaus, John W; Bickler, Philip E

2007-12-01

Pulse oximetry may overestimate arterial oxyhemoglobin saturation (Sao2) at low Sao2 levels in individuals with darkly pigmented skin, but other factors, such as gender and oximeter probe type, remain less studied. We studied the relationship between skin pigment and oximeter accuracy in 36 subjects (19 males, 17 females) of a range of skin tones. Clip-on type sensors and adhesive/disposable finger probes for the Masimo Radical, Nellcor N-595, and Nonin 9700 were studied. Semisupine subjects breathed air-nitrogen-CO2 mixtures via a mouthpiece to rapidly achieve 2- to 3-min stable plateaus of Sao2. Comparisons of Sao2 measured by pulse oximetry (Spo2) with Sao2 (by Radiometer OSM-3) were used in a multivariate model to assess the source of errors. The mean bias (Spo2 - Sao2) for the 70%-80% saturation range was 2.61% for the Masimo Radical with clip-on sensor, -1.58% for the Radical with disposable sensor, 2.59% for the Nellcor clip, 3.6% for the Nellcor disposable, -0.60% for the Nonin clip, and 2.43% for the Nonin disposable. Dark skin increased bias at low Sao2; greater bias was seen with adhesive/disposable sensors than with the clip-on types. Up to 10% differences in saturation estimates were found among different instruments in dark-skinned subjects at low Sao2. Multivariate analysis indicated that Sao2 level, sensor type, skin color, and gender were predictive of errors in Spo2 estimates at low Sao2 levels. The data suggest that clinically important bias should be considered when monitoring patients with saturations below 80%, especially those with darkly pigmented skin; but further study is needed to confirm these observations in the relevant populations.

Novel Pulse Oximetry Sonifications for Neonatal Oxygen Saturation Monitoring: A Laboratory Study.

PubMed

Hinckfuss, Kelly; Sanderson, Penelope; Loeb, Robert G; Liley, Helen G; Liu, David

2016-03-01

We aimed to test whether the use of novel pulse oximetry sounds (sonifications) better informs listeners when a neonate's oxygen saturation (SpO2) deviates from the recommended range. Variable-pitch pulse oximeters do not accurately inform clinicians via sound alone when SpO2 is outside the target range of 90% to 95% for neonates on supplemental oxygen. Risk of blindness, organ damage, and death increase if SpO2 remains outside the target range. A more informative sonification may improve clinicians' ability to maintain the target range. In two desktop experiments, nonclinicians' ability to detect SpO2 range and direction of change was tested with novel versus conventional sonifications of simulated patient data. In Experiment 1, a "shoulder" sonification used larger pitch differences between adjacent saturation percentages for SpO2 values outside the target range. In Experiment 2, a "beacon" sonification used equal-appearing pitch differences, but when SpO2 was outside the target range, a fixed-pitch reference tone from the center of the target SpO2 range preceded every fourth pulse tone. The beacon sonification improved range identification accuracy over the control display (85% vs. 60%; p < .001), but the shoulder sonification did not (55% vs. 52%). The beacon provided a distinct auditory alert and reference that significantly improved nonclinical participants' ability to identify SpO2 range. Adding a beacon to the variable-pitch pulse oximeter sound may help clinicians identify when, and by how much, a neonate's SpO2 deviates from the target range, particularly during patient transport situations when auditory information becomes essential. © 2015, Human Factors and Ergonomics Society.

Accuracy of Pulse Oximeters in Detecting Hypoxemia in Patients with Chronic Thromboembolic Pulmonary Hypertension

PubMed Central

Kohyama, Tomoki; Moriyama, Kiyoshi; Kanai, Riichiro; Kotani, Mariko; Uzawa, Kohji; Satoh, Toru; Yorozu, Tomoko

2015-01-01

Purpose Pulse oximetry is routinely used to continuously and non-invasively monitor arterial oxygen saturation (SaO2). When oxygen saturation by pulse oximeter (SpO2) overestimates SaO2, hypoxemia may be overlooked. We compared the SpO2 - SaO2 differences among three pulse oximeters in patients with chronic thromboembolic pulmonary hypertension (CTEPH) who spent their daily lives in a poor oxygen state. Material and Method This prospective observational study recruited 32 patients with CTEPH undergoing elective cardiac catheterization. As we collected arterial blood samples in the catheter laboratory, SpO2 values were simultaneously recorded. Three pulse oximeters were used on each patient, and SpO2 values were compared with oximetry readings using a blood gas analyzer. To determine the optimal SpO2 value by which to detect hypoxemia (SaO2≦90%), we generated receiver operating characteristic (ROC) curves for each pulse oximeter. Result The root mean square of each pulse oximeter was 1.79 (OLV-3100), 1.64 (N-BS), and 2.50 (Masimo Radical). The mean bias (SpO2 - SaO2) for the 90%–95% saturation range was significantly higher for Masimo Radical (0.19 +/- 1.78% [OLV-3100], 0.18 +/- 1.63% [N-BS], and 1.61 +/- 1.91% [Masimo Radical]; p<0.0001). The optimal SpO2 value to detect hypoxemia (SaO2≦90%) was 89% for OLV-3100, 90% for N-BS, and 92% for Masimo Radical. Conclusion We found that the biases and precision with which to detect hypoxemia differed among the three pulse oximeters. To avoid hypoxemia, the optimal SpO2 should be determined for each pulse oximeter. PMID:25978517

Perfusion index and plethysmographic variability index in patients with interscalene nerve catheters.

PubMed

Sebastiani, Anne; Philippi, Larissa; Boehme, Stefan; Closhen, Dorothea; Schmidtmann, Irene; Scherhag, Anton; Markstaller, Klaus; Engelhard, Kristin; Pestel, Gunther

2012-12-01

Interscalene nerve blocks provide adequate analgesia, but there are no objective criteria for early assessment of correct catheter placement. In the present study, pulse oximetry technology was used to evaluate changes in the perfusion index (PI) in both blocked and unblocked arms, and changes in the plethysmographic variability index (PVI) were evaluated once mechanical ventilation was instituted. The PI and PVI values were assessed using a Radical-7™ finger pulse oximetry device (Masimo Corp., Irvine, CA, USA) in both arms of 30 orthopedic patients who received an interscalene catheter at least 25 min before induction of general anesthesia. Data were evaluated at baseline, on application of local anesthetics; five, ten, and 15 min after onset of interscalene nerve blocks; after induction of general anesthesia; before and after a 500 mL colloid fluid challenge; and five minutes thereafter. In the 25 patients with successful blocks, the difference between the PI values in the blocked arm and the PI values in the contralateral arm increased within five minutes of the application of the local anesthetics (P < 0.05) and increased progressively until 15 min. After induction of general anesthesia, the PI increased in the unblocked arm while it remained relatively constant in the blocked arm, thus reducing the difference in the PI. A fluid challenge resulted in a decrease in PVI values in both arms. The perfusion index increases after successful interscalene nerve blockade and may be used as an indicator for successful block placement in awake patients. The PVI values before and after a fluid challenge can be useful to detect changes in preload, and this can be performed in both blocked and unblocked arms.

Retinal oximetry in patients with ischaemic retinal diseases.

PubMed

Rilvén, Sandra; Torp, Thomas Lee; Grauslund, Jakob

2017-03-01

The retinal oximeter is a new tool for non-invasive measurement of retinal oxygen saturation in humans. Several studies have investigated the associations between retinal oxygen saturation and retinal diseases. In the present systematic review, we examine whether there are associations between retinal oxygen saturation and retinal ischaemic diseases. We used PubMed and Embase to search for retinal oxygen saturation and retinal ischaemic diseases. Three separate searches identified a total of 79 publications. After two levels of manual screening, 10 studies were included: six about diabetic retinopathy (DR) and four about retinal vein occlusion. No studies about retinal artery occlusion were included. In diabetes, all studies found that increases in retinal venous oxygen saturation (rvSatO 2 ) were associated with present as well as increasing levels of DR. Four of six studies also found increased retinal arterial oxygen saturation (raSatO 2 ) in patients with DR. In patients with central retinal vein occlusion (CRVO), all studies found that rvSatO 2 was reduced, but raSatO 2 remained unchanged. Branch retinal vein occlusion was not associated with changes in retinal oxygen saturation, but this was based on a single study. In conclusion, DR is associated with increased rvSatO 2 and might also be related to increased raSatO 2 . Central retinal vein occlusion (CRVO) is correlated with increased rvSatO 2 but unrelated to raSatO 2 . Prospective studies are needed to expand these findings. These would tell whether retinal oximetry could be a potential tool for screening or a biomarker of treatment outcome in patients with ischaemic retinal diseases. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Comparison of oxygen saturation values obtained from fingers on physically restrained or unrestrained sides of the body.

PubMed

Korhan, Esra Akin; Yönt, Gülendam Hakverdioğlu; Khorshid, Leyla

2011-01-01

The aim of this study was to compare semiexperimentally the pulse oximetry values obtained from a finger on restrained or unrestrained sides of the body. The pulse oximeter provides a noninvasive measurement of the oxygen saturation of hemoglobin in arterial blood. One of the procedures most frequently applied to patients in intensive care units is the application of physical restraint. Circulation problems are the most important complication in patients who are physically restrained. Evaluation of oxygen saturation from body parts in which circulation is impeded or has deteriorated can cause false results. The research sample consisted of 30 hospitalized patients who participated in the study voluntarily and who were concordant with the inclusion criteria of the study. Patient information and patient follow-up forms were used for data collection. Pulse oximetry values were measured simultaneously using OxiMax Nellcor finger sensors from fingers on the restrained and unrestrained sides of the body. Numeric and percentile distributions were used in evaluating the sociodemographic properties of patients. A significant difference was found between the oxygen saturation values obtained from a finger of an arm that had been physically restrained and a finger of an arm that had not been physically restrained. The mean oxygen saturation value measured from a finger of an arm that had been physically restrained was found to be 93.40 (SD, 2.97), and the mean oxygen saturation value measured from a finger of an arm that had not been physically restrained was found to be 95.53 (SD, 2.38). The results of this study indicate that nurses should use a finger of an arm that is not physically restrained when evaluating oxygen saturation values to evaluate them correctly.

Acute changes in lung function associated with proximity to a steel plant: a randomized study.

PubMed

Dales, Robert; Kauri, Lisa Marie; Cakmak, Sabit; Mahmud, Mamun; Weichenthal, Scott A; Van Ryswyk, Keith; Kumarathasan, Premkumari; Thomson, Errol; Vincent, Renaud; Broad, Gayle; Liu, Ling

2013-05-01

Steel production is a major industry worldwide yet there is relatively little information on the pulmonary effects of air quality near steel manufacturing plants. The aim of this study was to examine how lung function changes acutely when healthy subjects are situated near a steel plant which is adjacent to a residential area. Sixty-one subjects were randomly assigned to spend 5 consecutive, 8-hour days in a residential neighborhood approximately 0.9km from a steel plant, or approximately 4.5km away at a college campus. Subjects crossed-over between sites after a nine-day washout period. Lung function was measured daily at both sites along with air pollutants including SO2, NO2, O3, PM2.5, and ultrafine particles. Diffusion capacity and pulse oximetry were also examined. Compared with the college site, the forced expiratory volume in 1-second/forced vital capacity, forced expiratory flow between 25% and 75% of the FVC, total lung capacity, functional residual capacity, and residual volume were lower near the steel plant by 0.67% (95% CI: 0.28, 1.06),1.62% (95% CI: 0.50, 2.75), 1.54% (95% CI: 0.68, 2.39), 3.54% (95% CI: 1.95, 5.13) and 11.3% (95% CI: 4.92, 17.75), respectively. Diffusion capacity, forced expiratory volume in 1s, and pulse oximetry were also lower near the plant but these effects were not statistically significant. Sulfur dioxide, ultrafine particulates, and oxides of nitrogen were greater near the steel plant site compared to the college site. Spending short periods of time near a steel plant is associated with a decrease in lung function. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Switch of noninvasive ventilation (NIV) to continuous positive airway pressure (CPAP) in patients with obesity hypoventilation syndrome: a pilot study.

PubMed

Orfanos, Sarah; Jaffuel, Dany; Perrin, Christophe; Molinari, Nicolas; Chanez, Pascal; Palot, Alain

2017-03-14

Obesity is a major worldwide public health issue. The main respiratory complication stemming from obesity is obesity hypoventilation syndrome (OHS). Most of the OHS patients diagnosed during an exacerbation are treated with non invasive ventilation (NIV). Up to date, no prospective study has demonstrated in real life conditions the feasibility of a systematic protocoled switch of NIV to continuous positive airway pressure (CPAP), once stability is achieved. In this prospective study, we included stable patients with OHS, with moderate to severe concomitant obstructive sleep apnea (OSA) and without obstructive pulmonary disease, who had been undergoing NIV for more than 2 months. The following measurements were performed, first with NIV and then after the switch to CPAP: diurnal arterial blood gas measurements; nocturnal oximetry and capnometry; mean compliance and AHI; measures of quality of life and quality of sleep. 22/30 patients accepted to participate in the study and 15/22 patients completed the study. There were no significant differences for pooled data in diurnal alveolar blood gases, nocturnal capnometry (p = 0.534), nocturnal oximetry (p = 0.218), mean compliance (p = 0.766), mean AHI (p = 0.334), quality of life or quality of sleep. Eighty percent of the patients treated in this study favored CPAP over NIV. This pilot study showed in real life conditions the possibility of a systematic switch of NIV to CPAP, in most stable patients with OHS, with similar efficacy on diurnal and nocturnal alveolar gas exchange, quality of life and quality of sleep. ISRCTN13981084 . Registered: 27 February 2017 (retrospectively registered).

Oxygen Saturation of Retinal Vessels in All Stages of Diabetic Retinopathy and Correlation to Ultra-Wide Field Fluorescein Angiography.

PubMed

Guduru, Abhilash; Martz, Teresa G; Waters, Alexa; Kshirsagar, Abhijit V; Garg, Seema

2016-10-01

The purpose of this study was to determine retinal hemoglobin oxygen saturation (SO2) in patients with diabetic retinopathy (DR) using retinal oximetry (RO) and to correlate the degree of retinal ischemia using intravenous fluorescein angiography (IVFA). This is a single-center cross-sectional cohort study. Twenty-seven controls and 60 adult patients with diabetes mellitus (16 without DR and 44 with DR) were enrolled. Patients were stratified according to DR severity. Using RO, SO2 was measured in major retinal arterioles (SaO2) and venules (SvO2). Using IVFA, the percentage of retinal ischemia in 31 patients with DR was calculated and correlated with RO. Pairwise one-way analysis of variance (ANOVA) showed a significant increase in SaO2 and SvO2 in patients with proliferative DR (PDR) compared with controls (SaO2: PDR, 100 ± 7% vs. controls, 91 ± 4% [P = 0.003]; SvO2: PDR, 66 ± 11% vs. controls, 53 ± 6% [P < 0.00001]). The percentage of retinal ischemia also increased with DR severity: ANOVA showed a significant difference in retinal ischemia between all categories of nonproliferative DR vs. PDR: 2.31 ± 2% vs. 7.92 ± 9% (P = 0.017), respectively. Pearson two-tailed correlation showed significant correlation between SaO2 and ischemia (R = 0.467, P = 0.011). Hemoglobin oxygen saturation of retinal arterioles and venules increases with DR severity; SaO2 correlates with increasing ischemia measured by IVFA. Retinal oximetry may complement current imaging strategies to noninvasively augment the diagnosis and risk stratification of patients with diabetes.

Pulse Oximetry and Auscultation for Congenital Heart Disease Detection.

PubMed

Hu, Xiao-Jing; Ma, Xiao-Jing; Zhao, Qu-Ming; Yan, Wei-Li; Ge, Xiao-Ling; Jia, Bing; Liu, Fang; Wu, Lin; Ye, Ming; Liang, Xue-Cun; Zhang, Jing; Gao, Yan; Zhai, Xiao-Wen; Huang, Guo-Ying

2017-10-01

Pulse oximetry (POX) has been confirmed as a specific screening modality for critical congenital heart disease (CCHD), with moderate sensitivity. However, POX is not able to detect most serious and critical cardiac lesions (major congenital heart disease [CHD]) without hypoxemia. In this study, we investigated the accuracy and feasibility of the addition of cardiac auscultation to POX as a screening method for asymptomatic major CHD. A multicenter prospective observational screening study was conducted at 15 hospitals in Shanghai between July 1, 2012, and December 31, 2014. Newborns with either an abnormal POX or cardiac auscultation were defined as screen positive. All screen-positive newborns underwent further echocardiography. False-negative results were identified by clinical follow-up, parents' feedback, and telephone review. We assessed the accuracy of POX plus cardiac auscultation for the detection of major CHD. CHD screening was completed in all 15 hospitals, with a screening rate of 94.0% to 99.8%. In total, 167 190 consecutive asymptomatic newborn infants were screened, of which 203 had major CHD (44 critical and 159 serious). The sensitivity of POX plus cardiac auscultation was 95.5% (95% confidence interval 84.9%-98.7%) for CCHD and 92.1% (95% confidence interval 87.7%-95.1%) for major CHD. The false-positive rate was 1.2% for detecting CCHD and 1.1% for detecting major CHD. In our current study, we show that using POX plus cardiac auscultation significantly improved the detection rate of major CHD in the early neonatal stage, with high sensitivity and a reasonable false-positive rate. It provides strong evidence and a reliable method for neonatal CHD screening. Copyright © 2017 by the American Academy of Pediatrics.

Home oximetry to screen for obstructive sleep apnoea in Down syndrome.

PubMed

Hill, Catherine M; Elphick, Heather E; Farquhar, Michael; Gringras, Paul; Pickering, Ruth M; Kingshott, Ruth N; Martin, Jane; Reynolds, Janine; Joyce, Anna; Gavlak, Johanna C; Evans, Hazel J

2018-05-14

Children with Down syndrome are at high risk of obstructive sleep apnoea (OSA) and screening is recommended. Diagnosis of OSA should be confirmed with multichannel sleep studies. We aimed to determine whether home pulse oximetry (HPO) discriminates children at high risk of OSA, who need further diagnostic multichannel sleep studies. Cross-sectional prospective study in a training sample recruited through three UK centres. Validation sample used single-centre retrospective analysis of clinical data. Children with Down syndrome aged 0.5-6 years. Diagnostic multichannel sleep study and HPO. Sensitivity and specificity of HPO to predict moderate-to-severe OSA. 161/202 children with Down syndrome met quality criteria for inclusion and 25 had OSA. In this training sample, the best HPO parameter predictors of OSA were the delta 12 s index >0.555 (sensitivity 92%, specificity 65%) and 3% oxyhaemoglobin (SpO 2 ) desaturation index (3% ODI)>6.15 dips/hour (sensitivity 92%, specificity 63%). Combining variables (delta 12 s index, 3% ODI, mean and minimum SpO 2 ) achieved sensitivity of 96% but reduced specificity to 52%. All predictors retained or improved sensitivity in a clinical validation sample of 50 children with variable loss of specificity, best overall was the delta 12 s index, a measure of baseline SpO 2 variability (sensitivity 92%; specificity 63%). HPO screening could halve the number of children with Down syndrome needing multichannel sleep studies and reduce the burden on children, families and health services alike. This approach offers a practical universal screening approach for OSA in Down syndrome that is accessible to the non-specialist paediatrician. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Nocturnal hypoventilation in neuromuscular disease: prevalence according to different definitions issued from the literature.

PubMed

Ogna, Adam; Quera Salva, Maria-Antonia; Prigent, Helene; Mroue, Ghassane; Vaugier, Isabelle; Annane, Djillali; Lofaso, Frederic; Orlikowski, David

2016-05-01

Restrictive respiratory failure is a major cause of morbidity and mortality in neuromuscular diseases (NMD). Home mechanical ventilation (HMV) is used to treat hypoventilation, identified by daytime hypercapnia or nocturnal desaturation. Recently, transcutaneous measure of CO2 (TcCO2) has been increasingly used to detect hypoventilation, using different cut-offs. We aimed to compare the prevalence of hypoventilation in an unselected adult NMD population according to different definitions issued from the literature. All consecutive nocturnal capno-oximetries performed between 2010 and 2014 in unventilated adult NMD patients were analysed retrospectively. Concomitant blood gas analysis and lung function data were collected. Patients on oxygen therapy were excluded. Hypoventilation was defined according to eight criteria, based on daytime PaCO2, daytime base excess, nocturnal SpO2 or TcCO2. Data from 232 patients were analysed (mean age 43.1 ± 15.4 years; 50.0 % women; vital capacity 59.2 ± 24.2 % of predicted). The hypoventilation prevalence was 10.3 to 61.2 %, depending on the used definition. The different definitions showed 49.1 to 94.8 % concordance (Cohen's kappa for agreement 0.115 to 0.763). Overall agreement between the eight definitions was poor (Light's kappa 0.267), and agreement between definitions based on nocturnal SpO2 and those based on TcCO2 was even lower (Light's kappa 0.204). We found large differences in hypoventilation prevalence according to the used definition. This has practical consequences, as HMV indication relies upon hypoventilation detection. We believe that capno-oximetry should be included in the diagnostic tools used to detect hypoventilation but this requires an update of consensus guidelines to agree upon the best definition.

Relating oxygen partial pressure, saturation and content: the haemoglobin-oxygen dissociation curve.

PubMed

Collins, Julie-Ann; Rudenski, Aram; Gibson, John; Howard, Luke; O'Driscoll, Ronan

2015-09-01

The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content), saturation (S O2 ) and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin-oxygen dissociation curve, a graphical representation of the relationship between oxygen satur-ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the S O2 in blood from patients with normal pH and S O2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (S pO2 ) is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (S aO2 ) as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable S pO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

Skin blood flow: a comparison of transcutaneous oximetry and laser Doppler flowmetry.

PubMed

Allen, P I; Goldman, M

1987-10-01

In normal limbs skin blood flow (SBF) falls on standing, but in ischaemic limbs there is a characteristic blush on dependancy. We studied the effect of changing posture in a range of ischaemic limbs, using two non-invasive techniques--laser Doppler (LD) and transcutaneous oximetry (TcPO2). Warmed TcPO2 and LD probes were placed over the first metatarsal cleft and SBF recorded with the limb horizontal, dependant and elevated. Ankle to brachial pressure ratios (A:B) were also measured. Twelve patients with lower limb ischaemia, mean A:B ratio 0.5 +/- 0.21 (+/- S.D.) were compared with 21 asymptomatic controls, mean A:B ratio 1.2 +/- 0.15. In the controls, neither TcPO2 nor LD values changed significantly with limb position. Both flux and oxygen tension were significantly lower in ischaemic limbs in all positions; on lowering the ischaemic limb, flux unexpectedly rose to 23.5 +/- 17.7 V from a mean of 14 + 9.0 V (horizontal). Both TcPO2 and LD correlated well with A:B ratio in two positions: horizontal r (TcPO2) = 0.73, r(LD) = 0.57; elevated r(TcPO2) = 0.78, r(LD) = 0.68. Overall there was a highly significant correlation between LD and TcPO2 (r = 0.6, P less than 0.001, Student's test), but this was strongest in the elevated position (r = 0.87, P less than 0.001). LD and TcPO2 relate to A:B ratio and to each other, particularly in the stressed limb; in the well perfused limb, the poorer correlation suggests skin perfusion is not linearly related to tissue oxygen tension.

Comparative analysis of the effects of two chest physical therapy interventions in patients with bronchiolitis during hospitalization period

PubMed Central

Remondini, Renata; dos Santos, Adriana Zamprônio; de Castro, Giselle; do Prado, Cristiane; da Silva, Luiz Vicente Ribeiro Ferreira

2014-01-01

Objective To evaluate and compare the effects of two chest physiotherapy interventions in patients hospitalized due to acute bronchiolitis. Methods Prospective randomized study with a sample of 83 calls for 29 patients aged between 3 months and 1 year hospitalized for acute bronchiolitis. Patients were distributed randomly into two groups: Group 1, submitted to postural drainage, tapping and tracheal aspiration; and Group 2, submitted to postural drainage, expiratory acceleration flow and tracheal aspiration. Assessments were made before and 10 and 60 minutes after the end of therapy. Patients also underwent drug treatment. The endpoint was to compare two physical therapy interventions as to clinical improvement in infants with acute bronchiolitis by means of oxygen saturation and the Respiratory Distress Assessment Instrument score. The parents/guardians was requested to answer a questionnaire about the treatment applied before the last evaluation in order to measure their satisfaction related to the interventions made. Results The groups were similar regarding the use of antibiotics and bronchodilators. A greater number of patients used corticosteroids in Group 2. A relevant improvement was observed on Respiratory Distress Assessment Instrument score with physical therapy, with reduction of the score 10 minutes after interventions, and the same score 60 minutes later, with no differences between techniques applied. There was no significant variation of pulse oximetry after chest physiotherapy. Most items assessed by the questionnaire had satisfactory answers. Conclusion No differences were observed between groups regarding the items assessed (time required to discharge from study, pulse oximetry in room air and disease severity according to the Respiratory Distress Assessment Instrument score). Parents answered positively about the effects of therapy in the majority of items in the questionnaire, both for the expiratory acceleration flow technique and for tapping. PMID:25628196

Near-infrared spectroscopy of the human brain during electroconvulsive therapy

NASA Astrophysics Data System (ADS)

Fantini, Sergio; Fabbri, Francesco; Nadgir, Shalini; Henry, Michael E.; Renshaw, Perry F.; Franceschini, Maria-Angela

2003-07-01

We report non-invasive, bilateral measurements of cerebral oxygenation performed with near-infrared spectroscopy (NIRS) on ten patients undergoing right unilateral electro-convulsive therapy (ECT). Right unilateral ECT consists of delivering an electrical current through the right brain hemisphere to induce a seizure, which is associated with significant changes in systemic and regional physiological parameters. In this work, we have examined the regional cerebral oxygenation (StO2) measured with NIRS on the right and left sides of the frontal brain region, and the systemic arterial oxygenation (SaO2) measured with pulse oximetry. On the ten patients examined, we have found that the decrease in the cerebral oxygenation on the side ipsilateral to the ECT electrical discharge (ΔStO2(ipsi)) is consistently stronger than the decrease on the contralateral side (ΔStO2(contra)). The average and standard deviation for the ipsilateral and contralateral oxygenation changes across the ten patients are ΔStO2(ipsi) = -22 +/- 10% and ΔStO2(contra) = -6 +/- 10%, respectively. By contrast, we observed two distinct behaviors in the arterial saturation; in five patients, SaO2 did not significantly change during the ECT procedure, and in three patients, SaO2 decreased by -16+/- 6%, an intermediate value with respect to the changes observed in StO2(ipsi) and StO2(contra) (we do not have the SaO2 recording in the remaining two patients for technical reasons). These results indicate that NIRS monitoring of the cerebral oxygenation during ECT has the potential of being a valuable addition to the standard monitoring of arterial saturation with pulse oximetry.

Clinical predictors of acute radiological pneumonia and hypoxaemia at high altitude.

PubMed Central

Lozano, J M; Steinhoff, M; Ruiz, J G; Mesa, M L; Martinez, N; Dussan, B

1994-01-01

Fast breathing has been recommended as a predictor of childhood pneumonia. Children living at high altitude, however, may breathe faster in response to the lower oxygen partial pressure, which may change the accuracy of prediction of a high respiratory rate. To assess the usefulness of clinical manifestations in the diagnosis of radiological pneumonia or hypoxaemia, or both, at high altitude (2640 m above sea level), 200 children aged 7 days to 36 months presenting to an urban emergency room with cough lasting less than seven days were studied. Parents were interviewed and the children evaluated using standard forms. The results of chest radiographs and pulse oximetry obtained after clinical examination were interpreted blind. Radiological pneumonia and haemoglobin oxygen saturation < 88% were used as 'gold standards'. One hundred and thirty (65%) and 125 (63%) children had radiological pneumonia and hypoxaemia respectively. Crepitations and decreased breath sounds were statistically associated with pneumonia, and rapid breathing as perceived by the child's mother, chest retractions, nasal flaring, and crepitations with hypoxaemia. The best single predictor of the presence of pneumonia is a high respiratory rate, although the results are not as good as those reported by other studies. A respiratory rate > or = 50/minute had good sensitivity (76%) and specificity (71%) for hypoxaemia in infants. Hypoxaemia had a good sensitivity and specificity for pneumonia mainly in infants (83% and 73%, respectively). Logistic regression analysis showed that decreased or increased respiratory sounds and crepitations were associated with pneumonia, and that hypoxaemia is the best predictor when auscultatory findings are excluded. These results suggest that some clinical predictors appear to be less accurate in Bogota than in places at lower altitude, and that pulse oximetry can be used for predicting pneumonia. PMID:7979525

Measurement of total hemoglobin reduces red cell transfusion in hospitalized patients undergoing cardiac surgery: a retrospective database analysis.

PubMed

Craver, Christopher; Belk, Kathy W; Myers, Gerard J

2018-01-01

Historically, perioperative hemoglobin monitoring has relied on calculated saturation, using blood gas devices that measure plasma hematocrit (Hct). Co-oximetry, which measures total hemoglobin (tHb), yields a more comprehensive assessment of hemodilution. The purpose of this study was to examine the association of tHb measurement by co-oximetry and Hct, using conductivity with red blood cell (RBC) transfusion, length of stay (LOS) and inpatient costs in patients having major cardiac surgery. A retrospective study was conducted on patients who underwent coronary artery bypass graft (CABG) and/or valve replacement (VR) procedures from January 2014 to June 2016, using MedAssets discharge data. The patient population was sub-divided by the measurement modality (tHb and Hct), using detailed billing records and Current Procedural Terminology coding. Cost was calculated using hospital-specific cost-to-charge ratios. Multivariable logistic regression was performed to identify significant drivers of RBC transfusion and resource utilization. The study population included 18,169 cardiovascular surgery patients. Hct-monitored patients accounted for 66% of the population and were more likely to have dual CABG and VR procedures (10.4% vs 8.9%, p=0.0069). After controlling for patient and hospital characteristics, as well as patient comorbidities, Hct-monitored patients had significantly higher RBC transfusion risk (OR=1.26, CI 1.15-1.38, p<0.0001), longer LOS (IRR=1.08, p<0.0001) and higher costs (IRR=1.15, p<0.0001) than tHb-monitored patients. RBC transfusions were a significant driver of LOS (IRR=1.25, p<0.0001) and cost (IRR=1.22, p<0.0001). tHb monitoring during cardiovascular surgery could offer a significant reduction in RBC transfusion, length of stay and hospital cost compared to Hct monitoring.

Comparative evaluation of neonatal bilirubin using Radiometer whole blood co-oximetry and plasma bilirubin methods from Roche Diagnostics and Ortho Clinical Diagnostics.

PubMed

Lano, Ian Marie; Lyon, Andrew W; Wang, Li; Ruskin, Rob; Lyon, Martha E

2018-03-01

Clinically significant variation has been reported within and between plasma and whole blood total bilirubin methods used to identify neonates for whom clinical intervention for hyperbilirubinemia may be required. To evaluate total bilirubin measurements between the Radiometer whole blood co-oximeter and plasma bilirubin methods from Roche Diagnostics and Ortho Clinical Diagnostics using neonatal specimens. Total bilirubin levels were analyzed by whole blood co-oximetry (Radiometer® ABL90). Specimens were centrifuged and plasma analyzed for total bilirubin with a diazo method (Roche Cobas® C-601) and a reflectance spectrophotometric BuBc dry film method (Ortho Clinical Diagnostics VITROS® 350). Results were evaluated by regression, Bland-Altman comparisons and t-tests. The patient correlation study yielded the following regression equations in μmol/L: a) Radiometer=1.03 Roche - 3.5μmol/L b) Radiometer=0.98 Ortho - 5.7μmol/L c) Roche=0.97 Ortho - 2.4μmol/L. The mean bias over the range of total bilirubin levels examined was -1.0μmol/L for the Radiometer versus the Roche (p≤0.305); -4.4μmol/L for the Radiometer versus Ortho (p≤0.005) and -4.4μmol/L for the Roche versus Ortho (p≤0.002). Whole blood total bilirubin measurement using the Radiometer ABL90 blood gas analyzer provides accurate and precise results compared to the Roche plasma diazo method. Compared to the reflectance spectrophotometric method, results are precise and had a small but statistically significant bias of -4.4μmol/L. Copyright © 2017 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Pulse Oximetry for the Detection of Obstructive Sleep Apnea Syndrome: Can the Memory Capacity of Oxygen Saturation Influence Their Diagnostic Accuracy?

PubMed Central

Nigro, Carlos A.; Dibur, Eduardo; Rhodius, Edgardo

2011-01-01

Objective. To assess the diagnostic ability of WristOx 3100 using its three different recording settings in patients with suspected obstructive sleep apnea syndrome (OSAS). Methods. All participants (135) performed the oximetry (three oximeters WristOx 3100) and polysomnography (PSG) simultaneously in the sleep laboratory. Both recordings were interpreted blindly. Each oximeter was set to one of three different recording settings (memory capabilities 0.25, 0.5, and 1 Hz). The software (nVision 5.1) calculated the adjusted O2 desaturation index-mean number of O2 desaturation per hour of analyzed recording ≥2, 3, and 4% (ADI2, 3, and 4). The ADI2, 3, and 4 cutoff points that better discriminated between subjects with or without OSAS arose from the receiver-operator characteristics (ROCs) curve analysis. OSAS was defined as a respiratory disturbance index (RDI) ≥ 5. Results. 101 patients were included (77 men, mean age 52, median RDI 22.6, median BMI 27.4 kg/m2). The area under the ROCs curves (AUC-ROCs) of ADI2, 3, and 4 with different data storage rates were similar (AUC-ROCs with data storage rates of 0.25/0.5/1 Hz: ADI2: 0.958/0.948/0.965, ADI3: 0.961/0.95/0.966, and ADI4: 0.957/0.949/0.963, P NS). Conclusions. The ability of WristOx 3100 to detect patients with OSAS was not affected by the data storage rate of the oxygen saturation signal. Both memory capacity of 0.25, 0.5, or 1 Hz showed a similar performance for the diagnosis of OSAS. PMID:23471171

Accuracy of pulse oximeters in detecting hypoxemia in patients with chronic thromboembolic pulmonary hypertension.

PubMed

Kohyama, Tomoki; Moriyama, Kiyoshi; Kanai, Riichiro; Kotani, Mariko; Uzawa, Kohji; Satoh, Toru; Yorozu, Tomoko

2015-01-01

Pulse oximetry is routinely used to continuously and non-invasively monitor arterial oxygen saturation (SaO2). When oxygen saturation by pulse oximeter (SpO2) overestimates SaO2, hypoxemia may be overlooked. We compared the SpO2 - SaO2 differences among three pulse oximeters in patients with chronic thromboembolic pulmonary hypertension (CTEPH) who spent their daily lives in a poor oxygen state. This prospective observational study recruited 32 patients with CTEPH undergoing elective cardiac catheterization. As we collected arterial blood samples in the catheter laboratory, SpO2 values were simultaneously recorded. Three pulse oximeters were used on each patient, and SpO2 values were compared with oximetry readings using a blood gas analyzer. To determine the optimal SpO2 value by which to detect hypoxemia (SaO2≦90%), we generated receiver operating characteristic (ROC) curves for each pulse oximeter. The root mean square of each pulse oximeter was 1.79 (OLV-3100), 1.64 (N-BS), and 2.50 (Masimo Radical). The mean bias (SpO2 - SaO2) for the 90%-95% saturation range was significantly higher for Masimo Radical (0.19 +/- 1.78% [OLV-3100], 0.18 +/- 1.63% [N-BS], and 1.61 +/- 1.91% [Masimo Radical]; p<0.0001). The optimal SpO2 value to detect hypoxemia (SaO2≦90%) was 89% for OLV-3100, 90% for N-BS, and 92% for Masimo Radical. We found that the biases and precision with which to detect hypoxemia differed among the three pulse oximeters. To avoid hypoxemia, the optimal SpO2 should be determined for each pulse oximeter.

Physiologic effect of repeated adrenaline (epinephrine) doses during cardiopulmonary resuscitation in the cath lab setting: A randomised porcine study.

PubMed

Hardig, Bjarne Madsen; Götberg, Michael; Rundgren, Malin; Götberg, Matthias; Zughaft, David; Kopotic, Robert; Wagner, Henrik

2016-04-01

This porcine study was designed to explore the effects of repetitive intravenous adrenaline doses on physiologic parameters during CPR. Thirty-six adult pigs were randomised to four injections of: adrenaline 0.02 mg(kgdose)(-1), adrenaline 0.03 mg(kgdose)(-1) or saline control. The effect on systolic, diastolic and mean arterial blood pressure, cerebral perfusion pressure (CePP), end tidal carbon dioxide (ETCO2), arterial oxygen saturation via pulse oximetry (SpO2), cerebral tissue oximetry (SctO2), were analysed immediately prior to each injection and at peak arterial systolic pressure and arterial blood gases were analysed at baseline and after 15 min. In the group given 0.02 mg(kgdose)(-1), there were increases in all arterial blood pressures at all 4 pressure peaks but CePP only increased significantly after peak 1. A decrease in ETCO2 following peak 1 and 2 was observed. SctO2 and SpO2 were lowered following injection 2 and beyond. In the group given a 0.03 mg(kgdose)(-1), all ABP's increased at the first 4 pressure peaks but CePP only following 3 pressure peaks. Lower ETCO2, SctO2 and SpO2 were seen at peak 1 and beyond. In the two adrenaline groups, pH and Base Excess were lower and lactate levels higher compared to baseline as well as compared to the control. Repetitive intravenous adrenaline doses increased ABP's and to some extent also CePP, but significantly decreased organ and brain perfusion. The institutional protocol number: Malmö/Lund Committee for Animal Experiment Ethics, approval reference number: M 192-10. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Analysis of respiratory events in obstructive sleep apnea syndrome: Inter-relations and association to simple nocturnal features.

PubMed

Ghandeharioun, H; Rezaeitalab, F; Lotfi, R

2016-01-01

This study carefully evaluates the association of different respiration-related events to each other and to simple nocturnal features in obstructive sleep apnea-hypopnea syndrome (OSAS). The events include apneas, hypopneas, respiratory event-related arousals and snores. We conducted a statistical study on 158 adults who underwent polysomnography between July 2012 and May 2014. To monitor relevance, along with linear statistical strategies like analysis of variance and bootstrapping a correlation coefficient standard error, the non-linear method of mutual information is also applied to illuminate vague results of linear techniques. Based on normalized mutual information weights (NMIW), indices of apnea are 1.3 times more relevant to AHI values than those of hypopnea. NMIW for the number of blood oxygen desaturation below 95% is considerable (0.531). The next relevant feature is "respiratory arousals index" with NMIW of 0.501. Snore indices (0.314), and BMI (0.203) take the next place. Based on NMIW values, snoring events are nearly one-third (29.9%) more dependent to hypopneas than RERAs. 1. The more sever the OSAS is, the more frequently the apneic events happen. 2. The association of snore with hypopnea/RERA revealed which is routinely ignored in regression-based OSAS modeling. 3. The statistical dependencies of oximetry features potentially can lead to home-based screening of OSAS. 4. Poor ESS-AHI relevance in the database under study indicates its disability for the OSA diagnosis compared to oximetry. 5. Based on poor RERA-snore/ESS relevance, detailed history of the symptoms plus polysomnography is suggested for accurate diagnosis of RERAs. Copyright © 2015 Sociedade Portuguesa de Pneumologia. Published by Elsevier España, S.L.U. All rights reserved.

[Methemoglobinemia after inhalation of poppers].

PubMed

Janssens, U; Hillen, S; Janssens, T; Grafe, J

2018-04-17

This case report presents a case of symptomatic methemoglobinemia (MetHb 31.6%) after inhalation of volatile nitrites (poppers). The patient's medical history and symptoms are discussed together with pathophysiology of methemoglobinemia, diagnostics, and antidote therapy. Pulse oxymetry, arterial blood gas analysis, and CO-oximetry receive particular attention as well as antidote therapy with methylene blue. The patient was treated successfully with intravenous methylene blue. Within 60 min methemoglobinemia returned to normal values (MetHb 0.6%). Stimulating compounds such as volatile nitrites (poppers) may lead to potentially fatal methemoglobinemia. Swift and accurate diagnosis and targeted therapy with methylene blue can lead to rapid recovery.

Wearable technology: role in respiratory health and disease.

PubMed

Aliverti, Andrea

2017-06-01

In the future, diagnostic devices will be able to monitor a patient's physiological or biochemical parameters continuously, under natural physiological conditions and in any environment through wearable biomedical sensors. Together with apps that capture and interpret data, and integrated enterprise and cloud data repositories, the networks of wearable devices and body area networks will constitute the healthcare's Internet of Things. In this review, four main areas of interest for respiratory healthcare are described: pulse oximetry, pulmonary ventilation, activity tracking and air quality assessment. Although several issues still need to be solved, smart wearable technologies will provide unique opportunities for the future or personalised respiratory medicine.

Tetany During Intravenous Conscious Sedation in Dentistry Resulting From Hyperventilation-Induced Hypocapnia.

PubMed

McCarthy, Caroline; Brady, Paul; O'Halloran, Ken D; McCreary, Christine

2016-01-01

Hyperventilation can be a manifestation of anxiety that involves abnormally fast breathing (tachypnea) and an elevated minute ventilation that exceeds metabolic demand. This report describes a case of hyperventilation-induced hypocapnia resulting in tetany in a 16-year-old girl undergoing orthodontic extractions under intravenous conscious sedation. Pulse oximetry is the gold standard respiratory-related index in conscious sedation. Although the parameter has great utility in determining oxygen desaturation, it provides no additional information on respiratory function, including, for example, respiratory rate. In this case, we found capnography to be a very useful aid to monitor respiration in this patient and also to treat the hypocapnia.

Wearable technology: role in respiratory health and disease

PubMed Central

2017-01-01

In the future, diagnostic devices will be able to monitor a patient’s physiological or biochemical parameters continuously, under natural physiological conditions and in any environment through wearable biomedical sensors. Together with apps that capture and interpret data, and integrated enterprise and cloud data repositories, the networks of wearable devices and body area networks will constitute the healthcare’s Internet of Things. In this review, four main areas of interest for respiratory healthcare are described: pulse oximetry, pulmonary ventilation, activity tracking and air quality assessment. Although several issues still need to be solved, smart wearable technologies will provide unique opportunities for the future or personalised respiratory medicine. PMID:28966692

Obstructive Sleep Apnea Devices for Out-Of-Center (OOC) Testing: Technology Evaluation

PubMed Central

Collop, Nancy A.; Tracy, Sharon L.; Kapur, Vishesh; Mehra, Reena; Kuhlmann, David; Fleishman, Sam A.; Ojile, Joseph M.

2011-01-01

Guidance is needed to help clinicians decide which out-of-center (OOC) testing devices are appropriate for diagnosing obstructive sleep apnea (OSA). A new classification system that details the type of signals measured by these devices is presented. This proposed system categorizes OOC devices based on measurements of Sleep, Cardiovascular, Oximetry, Position, Effort, and Respiratory (SCOPER) parameters. Criteria for evaluating the devices are also presented, which were generated from chosen pre-test and post-test probabilities. These criteria state that in patients with a high pretest probability of having OSA, the OOC testing device has a positive likelihood ratio (LR+) of 5 or greater coinciding with an in-lab-polysomnography (PSG)-generated apnea hypopnea index (AHI) ≥ 5, and an adequate sensitivity (at least 0.825). Since oximetry is a mandatory signal for scoring AHI using PSG, devices that do not incorporate oximetry were excluded. English peer-reviewed literature on FDA-approved devices utilizing more than 1 signal was reviewed according to the above criteria for 6 questions. These questions specifically addressed the adequacy of different respiratory and effort sensors and combinations thereof to diagnose OSA. In summary, the literature is currently inadequate to state with confidence that a thermistor alone without any effort sensor is adequate to diagnose OSA; if a thermal sensing device is used as the only measure of respiration, 2 effort belts are required as part of the montage and piezoelectric belts are acceptable in this context; nasal pressure can be an adequate measurement of respiration with no effort measure with the caveat that this may be device specific; nasal pressure may be used in combination with either 2 piezoelectric or respiratory inductance plethysmographic (RIP) belts (but not 1 piezoelectric belt); and there is insufficient evidence to state that both nasal pressure and thermistor are required to adequately diagnose OSA. With respect to alternative devices for diagnosing OSA, the data indicate that peripheral arterial tonometry (PAT) devices are adequate for the proposed use; the device based on cardiac signals shows promise, but more study is required as it has not been tested in the home setting; for the device based on end-tidal CO2 (ETCO2), it appears to be adequate for a hospital population; and for devices utilizing acoustic signals, the data are insufficient to determine whether the use of acoustic signals with other signals as a substitute for airflow is adequate to diagnose OSA. Standardized research is needed on OOC devices that report LR+ at the appropriate AHI (≥ 5) and scored according to the recommended definitions, while using appropriate research reporting and methodology to minimize bias. Citation: Collop NA; Tracy SL; Kapur V; Mehra R; Kuhlmann D; Fleishman SA; Ojile JM. Obstructive sleep apnea devices for out-of-center (OOC) testing: technology evaluation. J Clin Sleep Med 2011;7(5):531-548. PMID:22003351

Multicenter Study Validating Accuracy of a Continuous Respiratory Rate Measurement Derived From Pulse Oximetry: A Comparison With Capnography.

PubMed

Bergese, Sergio D; Mestek, Michael L; Kelley, Scott D; McIntyre, Robert; Uribe, Alberto A; Sethi, Rakesh; Watson, James N; Addison, Paul S

2017-04-01

Intermittent measurement of respiratory rate via observation is routine in many patient care settings. This approach has several inherent limitations that diminish the clinical utility of these measurements because it is intermittent, susceptible to human error, and requires clinical resources. As an alternative, a software application that derives continuous respiratory rate measurement from a standard pulse oximeter has been developed. We sought to determine the performance characteristics of this new technology by comparison with clinician-reviewed capnography waveforms in both healthy subjects and hospitalized patients in a low-acuity care setting. Two independent observational studies were conducted to validate the performance of the Medtronic Nellcor Respiration Rate Software application. One study enrolled 26 healthy volunteer subjects in a clinical laboratory, and a second multicenter study enrolled 53 hospitalized patients. During a 30-minute study period taking place while participants were breathing spontaneously, pulse oximeter and nasal/oral capnography waveforms were collected. Pulse oximeter waveforms were processed to determine respiratory rate via the Medtronic Nellcor Respiration Rate Software. Capnography waveforms reviewed by a clinician were used to determine the reference respiratory rate. A total of 23,243 paired observations between the pulse oximeter-derived respiratory rate and the capnography reference method were collected and examined. The mean reference-based respiratory rate was 15.3 ± 4.3 breaths per minute with a range of 4 to 34 breaths per minute. The Pearson correlation coefficient between the Medtronic Nellcor Respiration Rate Software values and the capnography reference respiratory rate is reported as a linear correlation, R, as 0.92 ± 0.02 (P < .001), whereas Lin's concordance correlation coefficient indicates an overall agreement of 0.85 ± 0.04 (95% confidence interval [CI] +0.76; +0.93) (healthy volunteers: 0.94 ± 0.02 [95% CI +0.91; +0.97]; hospitalized patients: 0.80 ± 0.06 [95% CI +0.68; +0.92]). The mean bias of the Medtronic Nellcor Respiration Rate Software was 0.18 breaths per minute with a precision (SD) of 1.65 breaths per minute (healthy volunteers: 0.37 ± 0.78 [95% limits of agreement: -1.16; +1.90] breaths per minute; hospitalized patients: 0.07 ± 1.99 [95% limits of agreement: -3.84; +3.97] breaths per minute). The root mean square deviation was 1.35 breaths per minute (healthy volunteers: 0.81; hospitalized patients: 1.60). These data demonstrate the performance of the Medtronic Nellcor Respiration Rate Software in healthy subjects and patients hospitalized in a low-acuity care setting when compared with clinician-reviewed capnography. The observed performance of this technology suggests that it may be a useful adjunct to continuous pulse oximetry monitoring by providing continuous respiratory rate measurements. The potential patient safety benefit of using combined continuous pulse oximetry and respiratory rate monitoring warrants assessment.

Multicenter Study Validating Accuracy of a Continuous Respiratory Rate Measurement Derived From Pulse Oximetry: A Comparison With Capnography

PubMed Central

Bergese, Sergio D.; Kelley, Scott D.; McIntyre, Robert; Uribe, Alberto A.; Sethi, Rakesh; Watson, James N.; Addison, Paul S.

2017-01-01

BACKGROUND: Intermittent measurement of respiratory rate via observation is routine in many patient care settings. This approach has several inherent limitations that diminish the clinical utility of these measurements because it is intermittent, susceptible to human error, and requires clinical resources. As an alternative, a software application that derives continuous respiratory rate measurement from a standard pulse oximeter has been developed. We sought to determine the performance characteristics of this new technology by comparison with clinician-reviewed capnography waveforms in both healthy subjects and hospitalized patients in a low-acuity care setting. METHODS: Two independent observational studies were conducted to validate the performance of the Medtronic NellcorTM Respiration Rate Software application. One study enrolled 26 healthy volunteer subjects in a clinical laboratory, and a second multicenter study enrolled 53 hospitalized patients. During a 30-minute study period taking place while participants were breathing spontaneously, pulse oximeter and nasal/oral capnography waveforms were collected. Pulse oximeter waveforms were processed to determine respiratory rate via the Medtronic Nellcor Respiration Rate Software. Capnography waveforms reviewed by a clinician were used to determine the reference respiratory rate. RESULTS: A total of 23,243 paired observations between the pulse oximeter-derived respiratory rate and the capnography reference method were collected and examined. The mean reference-based respiratory rate was 15.3 ± 4.3 breaths per minute with a range of 4 to 34 breaths per minute. The Pearson correlation coefficient between the Medtronic Nellcor Respiration Rate Software values and the capnography reference respiratory rate is reported as a linear correlation, R, as 0.92 ± 0.02 (P < .001), whereas Lin’s concordance correlation coefficient indicates an overall agreement of 0.85 ± 0.04 (95% confidence interval [CI] +0.76; +0.93) (healthy volunteers: 0.94 ± 0.02 [95% CI +0.91; +0.97]; hospitalized patients: 0.80 ± 0.06 [95% CI +0.68; +0.92]). The mean bias of the Medtronic Nellcor Respiration Rate Software was 0.18 breaths per minute with a precision (SD) of 1.65 breaths per minute (healthy volunteers: 0.37 ± 0.78 [95% limits of agreement: –1.16; +1.90] breaths per minute; hospitalized patients: 0.07 ± 1.99 [95% limits of agreement: –3.84; +3.97] breaths per minute). The root mean square deviation was 1.35 breaths per minute (healthy volunteers: 0.81; hospitalized patients: 1.60). CONCLUSIONS: These data demonstrate the performance of the Medtronic Nellcor Respiration Rate Software in healthy subjects and patients hospitalized in a low-acuity care setting when compared with clinician-reviewed capnography. The observed performance of this technology suggests that it may be a useful adjunct to continuous pulse oximetry monitoring by providing continuous respiratory rate measurements. The potential patient safety benefit of using combined continuous pulse oximetry and respiratory rate monitoring warrants assessment. PMID:28099286

RBC aggregation based system for long-term photoplethysmography (PPG): new prospects for PPG applications

NASA Astrophysics Data System (ADS)

Shvartsman, Leonid D.; Tverskoy, Boris

2015-03-01

We present system for long-term continuous PPG monitoring, and physical model for PPG analysis. The system is based on ideology of light scattering modulated by the process of RBC aggregation. OXIRATE's system works in reflection geometry. The sensor is tiny, completely mobile phone compatible, it can be placed nearly everywhere on the body surface. These technical features allow all-night comfortable PPG monitoring that was performed and analyzed. We can define various sleep stages on the basis of different reproducible time-behavior of PPG signal. Our system of PPG monitoring was used also for reflection pulse oximetry and for extreme PPG studies, such as diving.

Report of seven children with hepatopulmonary syndrome.

PubMed

Erge, Duygu; Selimoğlu, Mukadder Ayşe; Karakurt, Cemşit; Karabiber, Hamza; Elkıran, Özlem; Çatal, Ferat; Koroğlu, Reyhan

2014-12-01

Hepatopulmonary syndrome is an important pulmonary vascular complication of liver disease. Its diagnosis is based on the presence of hypoxaemia and the demonstration of intrapulmonary shunting by contrast-enhanced echocardiography or perfusion lung scanning. Awareness of this condition is critical to improve the outcomes of patients with chronic liver disease and/or portal hypertension because hepatopulmonary syndrome receives additional priority on the waiting list for transplantation. A non-invasive measurement of the blood oxygen saturation with pulse oximetry is recommended as a screening tool for this syndrome. The aim of this report was to present clinical and laboratory findings and follow-up of seven paediatric patients who were diagnosed with HPS at our centre.

Oxygen in acute and chronic wound healing.

PubMed

Schreml, S; Szeimies, R M; Prantl, L; Karrer, S; Landthaler, M; Babilas, P

2010-08-01

Oxygen is a prerequisite for successful wound healing due to the increased demand for reparative processes such as cell proliferation, bacterial defence, angiogenesis and collagen synthesis. Even though the role of oxygen in wound healing is not yet completely understood, many experimental and clinical observations have shown wound healing to be impaired under hypoxia. This article provides an overview on the role of oxygen in wound healing and chronic wound pathogenesis, a brief insight into systemic and topical oxygen treatment, and a discussion of the role of wound tissue oximetry. Thus, the aim is to improve the understanding of the role of oxygen in wound healing and to advance our management of wound patients.

Sleep apnea termination decreases cerebral blood volume: a near-infrared spectroscopy case study

NASA Astrophysics Data System (ADS)

Virtanen, Jaakko; Noponen, Tommi; Salmi, Tapani; Toppila, Jussi; Meriläinen, Pekka

2009-07-01

Medical near-infrared spectroscopy (NIRS) can be used to estimate cerebral haemodynamic changes non-invasively. Sleep apnea is a common sleep disorder where repetitive pauses in breathing decrease the quality of sleep and exposes the individual to various health problems. We have measured oxygenated and deoxygenated haemoglobin concentration changes during apneic events in sleep from the forehead of one subject using NIRS and used principal component analysis to extract extracerebral and cortical haemodynamic changes from NIRS signals. Comparison of NIRS signals with EEG, bioimpedance, and pulse oximetry data suggests that termination of apnea leads to decreases in cerebral blood volume and flow that may be related to neurological arousal via neurovascular coupling.

A systematic review of novel technology for monitoring infant and newborn heart rate.

PubMed

Kevat, Ajay C; Bullen, Denise V R; Davis, Peter G; Kamlin, C Omar F

2017-05-01

Heart rate (HR) is a vital sign for assessing the need for resuscitation. We performed a systematic review of studies assessing novel methods of measuring HR in newborns and infants in the neonatal unit. Two investigators completed independent literature searches. Identified papers were independently evaluated, and relevant data were extracted and analysed. This systematic review identified seven new technologies, including camera-based photoplethysmography, reflectance pulse oximetry, laser Doppler methods, capacitive sensors, piezoelectric sensors, electromyography and a digital stethoscope. Clinicians should be aware of several of these, which may become available for clinical use in the near future. ©2017 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

Tetany During Intravenous Conscious Sedation in Dentistry Resulting From Hyperventilation-Induced Hypocapnia

PubMed Central

McCarthy, Caroline; Brady, Paul; O'Halloran, Ken D.; McCreary, Christine

2016-01-01

Hyperventilation can be a manifestation of anxiety that involves abnormally fast breathing (tachypnea) and an elevated minute ventilation that exceeds metabolic demand. This report describes a case of hyperventilation-induced hypocapnia resulting in tetany in a 16-year-old girl undergoing orthodontic extractions under intravenous conscious sedation. Pulse oximetry is the gold standard respiratory-related index in conscious sedation. Although the parameter has great utility in determining oxygen desaturation, it provides no additional information on respiratory function, including, for example, respiratory rate. In this case, we found capnography to be a very useful aid to monitor respiration in this patient and also to treat the hypocapnia. PMID:26866408

Cerebral Oxygen Saturation to Guide Oxygen Delivery in Preterm Neonates for the Immediate Transition after Birth: A 2-Center Randomized Controlled Pilot Feasibility Trial.

PubMed

Pichler, Gerhard; Urlesberger, Berndt; Baik, Nariae; Schwaberger, Bernhard; Binder-Heschl, Corinna; Avian, Alexander; Pansy, Jasmin; Cheung, Po-Yin; Schmölzer, Georg Marcus

2016-03-01

To assess if monitoring of cerebral regional tissue oxygen saturation (crSO2) using near-infrared spectroscopy (NIRS) to guide respiratory and supplemental oxygen support reduces burden of cerebral hypoxia and hyperoxia in preterm neonates during resuscitation after birth. Preterm neonates <34(+0) weeks of gestation were included in a prospective randomized controlled pilot feasibility study at 2 tertiary level neonatal intensive care units. In a NIRS-visible group, crSO2 monitoring in addition to pulse oximetry was used to guide respiratory and supplemental oxygen support during the first 15 minutes after birth. In a NIRS-not-visible group, only pulse oximetry was used. The primary outcomes were burden of cerebral hypoxia (<10th percentile) or hyperoxia (>90th percentile) measured in %minutes crSO2 during the first 15 minutes after birth. Secondary outcomes were all cause of mortality and/or cerebral injury and neurologic outcome at term age. Allocation sequence was 1:1 with block-randomization of 30 preterm neonates at each site. In the NIRS-visible group burden of cerebral hypoxia in %minutes, crSO2 was halved, and the relative reduction was 55.4% (95% CI 37.6-73.2%; P = .028). Cerebral hyperoxia was observed in NIRS-visible group in 3 neonates with supplemental oxygen and in NIRS-not-visible group in 2. Cerebral injury rate and neurologic outcome at term age was similar in both groups. Two neonates died in the NIRS-not-visible group and none in the NIRS-visible group. No severe adverse reactions were observed. Reduction of burden of cerebral hypoxia during immediate transition and resuscitation after birth is feasible by crSO2 monitoring to guide respiratory and supplemental oxygen support. ClinicalTrials.gov: NCT02017691. Copyright © 2016 Elsevier Inc. All rights reserved.

Spin-Label Oximetry at Q- and W-Band

PubMed Central

Subczynski, W.K.; Mainali, L.; Camenisch, T.G.; Froncisz, W.; Hyde, J.S.

2011-01-01

Spin-lattice relaxation times (T1s) of both small water-soluble spin labels in the aqueous phase as well as lipid-type spin labels in membranes increase when the microwave frequency increases from 2 to 35 GHz (Hyde et al., J. Phys. Chem. B 108 [2004] 9524–9529). The T1 measured at W-band (94 GHz) for the water-soluble spin labels CTPO and TEMPONE (Froncisz et al., J. Magn. Reson. 193 [2008] 297–304) is, however, shorter than when measured at Q-band (35 GHz). In this paper, the decreasing trends at W-band have been confirmed for commonly used lipid-type spin labels in model membranes. It is concluded that the longest values of T1 will generally be found at Q-band, noting that long values are advantageous for measurement of bimolecular collisions with oxygen. The contribution of dissolved molecular oxygen to the relaxation rate was found to be independent of microwave frequency up to 94 GHz for lipid-type spin labels in membranes. This contribution is expressed in terms of the oxygen transport parameter W = T1−1(Air) − T1−1(N2), which is a function of both concentration and translational diffusion of oxygen in the local environment of a spin label. The new capabilities in measurement of the oxygen transport parameter using saturation-recovery (SR) EPR at Q- and W-band have been demonstrated in saturated (DMPC) and unsaturated (POPC) lipid bilayer membranes with the use of stearic acid (n-SASL) and phosphatidylcholine (n-PC) spin labels, and compared with results obtained earlier at X-band. SR EPR spin-label oximetry at Q- and W-band has the potential to be a powerful tool for studying samples of small volume, ~30 nL. These benefits, together with other factors such as a higher resonator efficiency parameter and a new technique for canceling free induction decay signals, are discussed. PMID:21277814

Discrepancies between arterial oxygen saturation and functional oxygen saturation measured with pulse oximetry in very preterm infants.

PubMed

Rosychuk, Rhonda J; Hudson-Mason, Ann; Eklund, Dianne; Lacaze-Masmonteil, Thierry

2012-01-01

Discrepancies between pulse oximetry saturation (SpO(2)) and arterial saturation (SaO(2)) at low blood oxygenation values have been previously reported with significant variations among instruments and studies. Whether pulse oximeters that attenuate motion artifact are less prone to such discrepancies is not well known. To prospectively assess the agreement of the Masimo V4 pulse oximeter within the critical 85-95% SpO(2) target range. For all consecutive babies with gestational age <33 weeks, postnatal age <7 days, and an umbilical arterial line, SpO(2) was measured continuously and SaO(2) analyzed on an as-needed basis. Bland-Altman techniques provided estimates of the difference (D = SaO(2) - SpO(2)), standard deviation (SD), and 95% limits of agreement (D ± 2*SD). There were 1,032 measurements (114 babies) with SpO(2) between 85 and 95%. The 95% limits of agreement were -2.0 ± 5.8, -2.4 ± 9.2, and -1.9 ± 5.3 in the SpO(2) categories 85-95, 85-89, and 91-95%, respectively. For the SpO(2) categories 85-89% and 91-95%, only 52% (53/101) and 59% (523/886) of SpO(2) values, respectively, corresponded to the analogous SaO(2) categories. In the 85-89% SpO(2) category, SaO(2) was lower than 85% in 39 of the 101 (39%) measurements. SaO(2) was lower on average than SpO(2) with an increased bias at lower saturation. The -2.4 ± 9.2 95% limits of agreement for SaO(2) - SpO(2) in the 85-89% SpO(2) category suggest that SpO(2) and SaO(2) are not interchangeable and intermittent SaO(2) assessments are warranted when the targeted SpO(2) is within this range. Copyright © 2011 S. Karger AG, Basel.

Transcutaneous oximetry: normal values for the lower limb.

PubMed

Blake, Denise F; Young, Derelle A; Brown, Lawrence H

2014-09-01

Current guidelines for transcutaneous oximetry measurement (TCOM) for the lower limb define tissue hypoxia as a transcutaneous oxygen partial pressure < 40 mmHg. Values obtained with some newer machines and current research bring these reference values into question. To determine 'normal' TCOM values for the lower limb in healthy, non-smoking adults using the TCM400 oximeter with tc Sensor E5250. Thirty-two healthy, non-smoking volunteers had TCOM performed at six positions on the lower leg and foot. Measurements were taken with subjects lying supine breathing air, then with leg elevated and whilst breathing 100 % oxygen. Room-air TCOM values (mean mmHg, 95 % confidence interval (CI) ) were: lateral leg 41.3, CI 37.8 to 44.7; lateral malleolus 38.6, CI 34.1 to 43.1; medial malleolus 43.9, CI 40.2 to 47.6; dorsum, between first and second toe 39.3, CI 35.9 to 42.7; dorsum, proximal to fifth metatarsal-phalangeal joint 46.4, CI 43.4 to 49.3; plantar 52.3, CI 49.6 to 55.1. Using the currently accepted value of less than 40 mmHg for tissue hypoxia, 24 of our 32 'healthy' subjects had at least one air sensor reading that would have been classified as hypoxic. Seventeen subjects had TCOM values less than 100 mmHg when breathing 100 % normobaric oxygen. Normal lower limb TCOM readings using the TCOM400 with tc Sensor E5250 may be lower than 40 mmHg, used to define tissue hypoxia, but consistent with the wide range of values found in the literature. Because of the wide variability in TCOM at the different sensor sites we cannot recommend one TCOM value as indicative of tissue hypoxia. A thorough clinical assessment of the patient is essential to establish appropriateness for hyperbaric oxygen treatment, with TCOM used as an aid to help guide this decision, but not as an absolute diagnostic tool.

Modulation of tumor hypoxia by topical formulations with vasodilators for enhancing therapy.

PubMed

Abramovic, Zrinka; Hou, Huagang; Julijana, Kristl; Sentjurc, Marjeta; Lariviere, Jean P; Swartz, Harold M; Khan, Nadeem

2011-01-01

Tumor hypoxia is a well known therapeutic problem which contributes to radioresistance and aggressive tumor characteristics. Lack of techniques for repeated measurements of tumor oxygenation (pO(2), partial pressure of oxygen) has restricted the optimization of hypoxia modifying methods and their efficacious application with radiotherapy. We have investigated a non-invasive method to enhance tissue pO(2) of peripheral tumors using topical application of formulations with BN (Benzyl Nicotinate), a vasodilator, and have used EPR (Electron Paramagnetic Resonance) oximetry to follow its effect on tumor oxygenation.We incorporated 2.5% BN in both hydrogel and microemulsions and investigated the effects on pO(2) of subcutaneous RIF-1 (Radiation Induced Fibrosarcoma) tumors in C3H mice. The experiments were repeated for five consecutive days. The topical application of BN in hydrogel led to a significant increase from a pre-treatment pO(2) of 9.3 mmHg to 11 - 16 mmHg at 30 - 50 min on day 1. However, the magnitude and the time of significant increase in pO(2) decreased with repeated topical applications. The BN in a microemulsion resulted in a significant increase from a baseline pO(2) of 8.8 mmHg to 13 - 18 mmHg at 10 - 50 min on day 1. Experiments repeated on subsequent days showed a decline in the magnitude of pO(2) increase on repeated applications. No significant change in tumor pO(2) was observed in experiments with formulations without BN (vehicle only).EPR oximetry was successfully used to follow the temporal changes in tumor pO(2) during repeated applications for five consecutive days. This approach can be potentially used to enhance radiotherapeutic outcome by scheduling radiation doses when an increase in tumor pO(2) is observed after topical applications of BN formulations.

Analytical and pre-analytical performance characteristics of a novel cartridge-type blood gas analyzer for point-of-care and laboratory testing.

PubMed

Oyaert, Matthijs; Van Maerken, Tom; Bridts, Silke; Van Loon, Silvi; Laverge, Heleen; Stove, Veronique

2018-03-01

Point-of-care blood gas test results may benefit therapeutic decision making by their immediate impact on patient care. We evaluated the (pre-)analytical performance of a novel cartridge-type blood gas analyzer, the GEM Premier 5000 (Werfen), for the determination of pH, partial carbon dioxide pressure (pCO 2 ), partial oxygen pressure (pO 2 ), sodium (Na + ), potassium (K + ), chloride (Cl - ), ionized calcium ( i Ca 2+ ), glucose, lactate, and total hemoglobin (tHb). Total imprecision was estimated according to the CLSI EP5-A2 protocol. The estimated total error was calculated based on the mean of the range claimed by the manufacturer. Based on the CLSI EP9-A2 evaluation protocol, a method comparison with the Siemens RapidPoint 500 and Abbott i-STAT CG8+ was performed. Obtained data were compared against preset quality specifications. Interference of potential pre-analytical confounders on co-oximetry and electrolyte concentrations were studied. The analytical performance was acceptable for all parameters tested. Method comparison demonstrated good agreement to the RapidPoint 500 and i-STAT CG8+, except for some parameters (RapidPoint 500: pCO 2 , K + , lactate and tHb; i-STAT CG8+: pO 2 , Na + , i Ca 2+ and tHb) for which significant differences between analyzers were recorded. No interference of lipemia or methylene blue on CO-oximetry results was found. On the contrary, significant interference for benzalkonium and hemolysis on electrolyte measurements were found, for which the user is notified by an interferent specific flag. Identification of sample errors from pre-analytical sources, such as interferences and automatic corrective actions, along with the analytical performance, ease of use and low maintenance time of the instrument, makes the evaluated instrument a suitable blood gas analyzer for both POCT and laboratory use. Copyright © 2018 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

Clinical trial on the efficacy of exhaled carbon monoxide measurement in smoking cessation in primary health care

PubMed Central

2012-01-01

Background Smoking cessation is beneficial for our health at any point in life, both in healthy people and in people already suffering from a smoking-related disease. Any help to quit smoking can produce considerable benefits for Public Health. The purpose of the present study is to evaluate the efficacy of the CO-oximetry technique together with brief advice in smoking cessation, in terms of reduction of the number of cigarettes or in the variation of the motivation to quit smoking at month 12 compared with brief advice alone. Methods/Design Randomised, parallel, single-blind clinical trial in a primary health care setting in Majorca (Spain). Smokers in contemplation or pre-contemplation phase will be included in the study. Exclusion criteria: Smokers in preparation phase, subjects with a terminal illness or whose health status does not allow them to understand the study or complete the informed consent, and pregnant or breastfeeding women. The subjects will be randomly assigned to the control group (CG) or the intervention group (IG). The CG will receive brief advice, and the IG will receive brief advice together with a measurement of exhaled CO. There will be follow-up evaluations at 6 and 12 months after inclusion. 471 subjects will be needed per group in order to detect a difference between groups ≥ 5%. Primary outcome: sustained smoking cessation (at 6 and 12 months) confirmed by urine cotinine test. Secondary outcomes: point smoking cessation at 6 and 12 months both confirmed by urine cotinine analysis and self-reported, reduction in cigarette consumption, and variation in phase of smoking cessation. Discussion CO-oximetry is an inexpensive, non-invasive, fast technique that requires little technical training; making it a technique for risk assessment in smokers that can be easily applied in primary care and, if proven effective, could serve as a reinforcement aid in smoking cessation intervention activities. Trial Registration Current Controlled Trials ISRCTN67499921 PMID:22551017

Detecting obstructive sleep apnea in children by self-affine visualization of oximetry.

PubMed

Garde, Ainara; Dekhordi, Parastoo; Petersen, Christian L; Ansermino, J Mark; Dumont, Guy A

2017-07-01

Obstructive sleep apnea (OSA), characterized by cessations of breathing during sleep due to upper airway collapse, can affect the healthy growth and development of children. The gold standard for OSA diagnosis, polysomnography(PSG), is expensive and resource intensive, resulting in long waiting lists to perform a PSG. Previously, we investigated the time-frequency analysis of blood oxygen saturation (SpO 2 ) to screen for OSA. We used overnight pulse oximetry from 146 children, collected using a smartphone-based pulse oximeter (Phone Oximeter), simultaneously with standard PSG. Sleep technicians manually scored PSG and provided the average of apnea/hypoapnea events per hour (AHI). In this study, we proposed an alternative method for analyzing SpO 2 , in which a set of contracting transformations form a self-affine set with a 2D attractor, previously developed for qualitative visualization of the photoplethysmogram and electroencephalogram. We applied this technique to the overnight SpO 2 signal from individual patients and extracted features based on the distribution of points (radius and angle) in the visualization. The cloud of points in children without OSA (NonOSA) was more confined than in children with OSA, which was reflected by more empty pixels (radius and angles). The maximum value, skewness and standard deviation of the distribution of points located at different radius and angles were significantly (Bonferroni corrected) higher in NonOSA compared to OSA children. To detect OSA defined at different levels (AHI≥5, AHI≥10 and AHI≥15), three multivariate logistic regression models were implemented using a stepwise feature selection and internally validated through bootstrapping. The models (AHI≥5, AHI≥10, AHI≥15), consisting of 3, 4 and 1 features respectively, provided a bootstrap-corrected AUC of 73%, 81%, 73%. Thus, applying this visualization to nocturnal SpO 2 could yield both visual and quantitative information that might be useful for screening children for OSA.

Changes in retinal venular oxygen saturation predict activity of proliferative diabetic retinopathy 3 months after panretinal photocoagulation.

PubMed

Torp, Thomas Lee; Kawasaki, Ryo; Wong, Tien Yin; Peto, Tunde; Grauslund, Jakob

2018-03-01

Proliferative diabetic retinopathy (PDR) is a severe blinding condition. We investigated whether retinal metabolism, measured by retinal oximetry, may predict PDR activity after panretinal laser photocoagulation (PRP). We performed a prospective, interventional, clinical study of patients with treatment-naive PDR. Wide-field fluorescein angiography (OPTOS, Optomap) and global and focal retinal oximetry (Oxymap T1) were performed at baseline (BL), and 3 months (3M) after PRP. Angiographic findings were used to divide patients according to progression or non-progression of PDR after PRP. We evaluated differences in global and focal retinal oxygen saturation between patients with and without progression of PDR after PRP treatment. We included 45 eyes of 37 patients (median age and duration of diabetes were 51.6 and 20 years). Eyes with progression of PDR developed a higher retinal venous oxygen saturation than eyes with non-progression at 3M (global: +5.9% (95% CI -1.5 to 12.9), focal: +5.4%, (95% CI -4.1 to 14.8)). Likewise, progression of PDR was associated with a lower arteriovenular (AV) oxygen difference between BL and 3M (global: -6.1%, (95% CI -13.4 to -1.4), focal: -4.5% (95% CI -12.1 to 3.2)). In a multiple logistic regression model, increment in global retinal venular oxygen saturation (OR 1.30 per 1%-point increment, p=0.017) and decrement in AV oxygen saturation difference (OR 0.72 per 1%-point increment, p=0.016) at 3M independently predicted progression of PDR. Development of higher retinal venular and lower AV global oxygen saturation independently predicts progression of PDR despite standard PRP and might be a potential non-invasive marker of angiogenic disease activity. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

MODULATION OF TUMOR HYPOXIA BY TOPICAL FORMULATIONS WITH VASODILATORS FOR ENHANCING THERAPY

PubMed Central

Abramovic, Zrinka; Hou, Huagang; Julijana, Kristl; Sentjurc, Marjeta; Lariviere, Jean P; Swartz, Harold M; Khan, Nadeem

2011-01-01

Tumor hypoxia is a well known therapeutic problem which contributes to radioresistance and aggressive tumor characteristics. Lack of techniques for repeated measurements of tumor oxygen (pO2, partial pressure of oxygen) has restricted the optimization of hypoxia modifying methods and their efficacious application with radiotherapy. We have investigated a non-invasive method to enhance tissue pO2 of peripheral tumors using topical application of formulations with BN (Benzyl Nicotinate), a vasodilator, and have used EPR (Electron Paramagnetic Resonance) oximetry to follow its effect on tumor oxygenation. We incorporated 2.5% BN in both hydrogel and microemulsions and investigated the effects on pO2 of subcutaneous RIF-1 (Radiation Induced Fibrosarcoma) tumors in C3H mice. The experiments were repeated for five consecutive days. The topical application of BN in hydrogel led to a significant increase from a pre-treatment pO2 of 9.3 mmHg to 11 - 16 mmHg at 30 - 50 min on day 1. However, the magnitude and the time of significant increase in pO2 decreased with repeated topical applications. The BN in a microemulsion resulted in a significant increase from a baseline pO2 of 8.8 mmHg to 13 - 18 mmHg at 10 - 50 min on day 1. Experiments repeated on subsequent days showed a decline in the magnitude of pO2 increase on repeated applications. No significant change in tumor pO2 was observed in experiments with formulations without BN (vehicle only). EPR oximetry was successfully used to follow the temporal changes in tumor pO2 during repeated applications for five consecutive days. This approach could be potentially used to enhance radiotherapeutic outcome by scheduling radiation doses when an increase in tumor pO2 is observed after topical applications of BN formulations. PMID:21445772

Diagnostic accuracy of a two-stage model for detecting obstructive sleep apnoea in chronic tetraplegia.

PubMed

Graco, Marnie; Schembri, Rachel; Cross, Susan; Thiyagarajan, Chinnaya; Shafazand, Shirin; Ayas, Najib T; Nash, Mark S; Vu, Viet H; Ruehland, Warren R; Chai-Coetzer, Ching Li; Rochford, Peter; Churchward, Thomas; Green, Sally E; Berlowitz, David J

2018-05-07

Obstructive sleep apnoea (OSA) is highly prevalent in people with spinal cord injury (SCI). Polysomnography (PSG) is the gold-standard diagnostic test for OSA, however PSG is expensive and frequently inaccessible, especially in SCI. A two-stage model, incorporating a questionnaire followed by oximetry, has been found to accurately detect moderate to severe OSA (MS-OSA) in a non-disabled primary care population. This study investigated the accuracy of the two-stage model in chronic tetraplegia using both the original model and a modified version for tetraplegia. An existing data set of 78 people with tetraplegia was used to modify the original two-stage model. Multivariable analysis identified significant risk factors for inclusion in a new tetraplegia-specific questionnaire. Receiver operating characteristic (ROC) curve analyses of the questionnaires and oximetry established thresholds for diagnosing MS-OSA. The accuracy of both models in diagnosing MS-OSA was prospectively evaluated in 100 participants with chronic tetraplegia across four international SCI units. Injury completeness, sleepiness, self-reported snoring and apnoeas were included in the modified questionnaire, which was highly predictive of MS-OSA (ROC area under the curve 0.87 (95% CI 0.79 to 0.95)). The 3% oxygen desaturation index was also highly predictive (0.93 (0.87-0.98)). The two-stage model with modified questionnaire had a sensitivity and specificity of 83% (66-93) and 88% (75-94) in the development group, and 77% (65-87) and 81% (68-90) in the validation group. Similar results were demonstrated with the original model. Implementation of this simple alternative to full PSG could substantially increase the detection of OSA in patients with tetraplegia and improve access to treatments. Results, ACTRN12615000896572 (The Australian and New Zealand Clinical Trials Registry) and pre-results, NCT02176928 (clinicaltrials.gov). © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Effects of Changes in Arterial Carbon Dioxide and Oxygen Partial Pressures on Cerebral Oximeter Performance.

PubMed

Schober, Andrew; Feiner, John R; Bickler, Philip E; Rollins, Mark D

2018-01-01

Cerebral oximetry (cerebral oxygen saturation; ScO2) is used to noninvasively monitor cerebral oxygenation. ScO2 readings are based on the fraction of reduced and oxidized hemoglobin as an indirect estimate of brain tissue oxygenation and assume a static ratio of arterial to venous intracranial blood. Conditions that alter cerebral blood flow, such as acute changes in PaCO2, may decrease accuracy. We assessed the performance of two commercial cerebral oximeters across a range of oxygen concentrations during normocapnia and hypocapnia. Casmed FORE-SIGHT Elite (CAS Medical Systems, Inc., USA) and Covidien INVOS 5100C (Covidien, USA) oximeter sensors were placed on 12 healthy volunteers. The fractional inspired oxygen tension was varied to achieve seven steady-state levels including hypoxic and hyperoxic PaO2 values. ScO2 and simultaneous arterial and jugular venous blood gas measurements were obtained with both normocapnia and hypocapnia. Oximeter bias was calculated as the difference between the ScO2 and reference saturation using manufacturer-specified weighting ratios from the arterial and venous samples. FORE-SIGHT Elite bias was greater during hypocapnia as compared with normocapnia (4 ± 9% vs. 0 ± 6%; P < 0.001). The INVOS 5100C bias was also lower during normocapnia (5 ± 15% vs. 3 ± 12%; P = 0.01). Hypocapnia resulted in a significant decrease in mixed venous oxygen saturation and mixed venous oxygen tension, as well as increased oxygen extraction across fractional inspired oxygen tension levels (P < 0.0001). Bias increased significantly with increasing oxygen extraction (P < 0.0001). Changes in PaCO2 affect cerebral oximeter accuracy, and increased bias occurs with hypocapnia. Decreased accuracy may represent an incorrect assumption of a static arterial-venous blood fraction. Understanding cerebral oximetry limitations is especially important in patients at risk for hypoxia-induced brain injury, where PaCO2 may be purposefully altered.

The Pēpi-Pod study: Overnight video, oximetry and thermal environment while using an in-bed sleep device for sudden unexpected death in infancy prevention.

PubMed

Tipene-Leach, David; Baddock, Sally A; Williams, Sheila M; Tangiora, Angeline; Jones, Raymond; McElnay, Caroline; Taylor, Barry J

2018-06-01

The aim of this study was to identify the potential risks and benefits of sleeping infants in a Pēpi-Pod distributed to families with high risk of sudden unexpected death in infancy compared to a bassinet. Forty-five mostly indigenous Māori mothers who were referred by local health providers to receive a Pēpi-Pod were surveyed at recruitment, 1 and 3 months. A sleep study at 1 month included infrared video, oximetry and temperature measures. When compared with 89 historical bassinet controls, an intention-to-treat analysis of questionnaires showed no increase in direct bed sharing but demonstrated significantly less sharing of the maternal bedroom at both interviews, with the majority of those not sleeping in the maternal bedroom, actually sleeping in the living room. The 1 month 'as-used' analysis showed poorer maternal sleep quality. The 'as-used' analysis of video data (24 Pēpi-Pod and 113 bassinet infants) also showed no increase in direct bed sharing, head covering or prone/side sleep position. Differences in oxygen saturation were not significant, but heart rate was higher in the Pēpi-Pod infants by 8.37 bpm (95% confidence interval 4.40, 12.14). Time in the thermal comfort zone was not different between groups despite Pēpi-Pod infants being situated in significantly warmer rooms. Overall, we found that most differences in infant risk behaviours in a Pēpi-Pod compared to a bassinet were small, with confidence intervals excluding meaningful differences. We noted poorer maternal sleep quality at 1 month. Higher infant heart rates in the Pēpi-Pod group may be related to higher room temperatures. The Pēpi-Pod appears physiologically safe but is associated with lower reported maternal sleep quality. © 2018 Paediatrics and Child Health Division (The Royal Australasian College of Physicians).

Association between severity of untreated sleep apnoea and postoperative complications following major cardiac surgery: a prospective observational cohort study.

PubMed

Mason, Martina; Hernández Sánchez, Jules; Vuylsteke, Alain; Smith, Ian

2017-09-01

To examine whether untreated sleep apnoea is associated with prolonged Intensive Care Unit (ICU) stay and increased frequency of postoperative ICU complications, in patients undergoing major cardiac surgery. Adult patients, undergoing elective coronary artery bypass grafting with or without cardiac valve surgery, between March 2013 and July 2014, were considered. We excluded patients participating in other interventional studies, those who had a tracheostomy before surgery, required emergency surgery or were due to be admitted on the day of surgery. Patients underwent inpatient overnight oximetry on the night prior to their surgery to assess for the presence of sleep apnoea. Since oximetry alone cannot differentiate obstructive from central apnoea, the results are reported as sleep apnoea which was diagnosed in patients with an arterial oxygen desaturation index (ODI) ≥ 5/h. The primary outcome measure was length of stay (LoS) in ICU in days. The secondary outcome was a composite measure of postoperative complications in ICU. Multivariate models were developed to assess associations between ODI and the primary and secondary outcome measures, adjusting for preselected predictor variables, relative to primary and secondary outcomes. There was no significant association between ODI and ICU LoS, HR 1.0, 95% CI 0.99-1.02; p = 0.12. However we did find a significant association between ODI and postoperative complications in the ICU, OR = 1.1; 95% CI 1.02-1.17; p = 0.014. The probability of developing complications rose with higher ODI, reflecting sleep apnoea severity. Acknowledging the limitations of this prospective study, untreated sleep apnoea did not predict an increased length of stay in ICU but we do report an association with postoperative complications in patients undergoing major cardiac surgery. Copyright © 2017 Elsevier B.V. All rights reserved.

Direct Measurements of Oxygen Gradients in Spheroid Culture System Using Electron Parametric Resonance Oximetry

PubMed Central

Langan, Laura M.; Dodd, Nicholas J. F.; Owen, Stewart F.; Purcell, Wendy M.; Jackson, Simon K.; Jha, Awadhesh N.

2016-01-01

Advanced in vitro culture from tissues of different origin includes three-dimensional (3D) organoid micro structures that may mimic conditions in vivo. One example of simple 3D culture is spheroids; ball shaped structures typically used as liver and tumour models. Oxygen is critically important in physiological processes, but is difficult to quantify in 3D culture: and the question arises, how small does a spheroid have to be to have minimal micro-environment formation? This question is of particular importance in the growing field of 3D based models for toxicological assessment. Here, we describe a simple non-invasive approach modified for the quantitative measurement and subsequent evaluation of oxygen gradients in spheroids developed from a non-malignant fish cell line (i.e. RTG-2 cells) using Electron Paramagnetic Resonance (EPR) oximetry. Sonication of the paramagnetic probe Lithium phthalocyanine (LiPc) allows for incorporation of probe particulates into spheroid during its formation. Spectra signal strength after incorporation of probe into spheroid indicated that a volume of 20 μl of probe (stock solution: 0.10 mg/mL) is sufficient to provide a strong spectra across a range of spheroid sizes. The addition of non-toxic probes (that do not produce or consume oxygen) report on oxygen diffusion throughout the spheroid as a function of size. We provide evidence supporting the use of this model over a range of initial cell seeding densities and spheroid sizes with the production of oxygen distribution as a function of these parameters. In our spheroid model, lower cell seeding densities (∼2,500 cells/spheroid) and absolute size (118±32 μm) allow control of factors such as pre-existing stresses (e.g. ∼ 2% normoxic/hypoxic interface) for more accurate measurement of treatment response. The applied methodology provides an elegant, widely applicable approach to directly characterize spheroid (and other organoid) cultures in biomedical and toxicological research. PMID:26900704

Direct Measurements of Oxygen Gradients in Spheroid Culture System Using Electron Parametric Resonance Oximetry.

PubMed

Langan, Laura M; Dodd, Nicholas J F; Owen, Stewart F; Purcell, Wendy M; Jackson, Simon K; Jha, Awadhesh N

2016-01-01

Advanced in vitro culture from tissues of different origin includes three-dimensional (3D) organoid micro structures that may mimic conditions in vivo. One example of simple 3D culture is spheroids; ball shaped structures typically used as liver and tumour models. Oxygen is critically important in physiological processes, but is difficult to quantify in 3D culture: and the question arises, how small does a spheroid have to be to have minimal micro-environment formation? This question is of particular importance in the growing field of 3D based models for toxicological assessment. Here, we describe a simple non-invasive approach modified for the quantitative measurement and subsequent evaluation of oxygen gradients in spheroids developed from a non-malignant fish cell line (i.e. RTG-2 cells) using Electron Paramagnetic Resonance (EPR) oximetry. Sonication of the paramagnetic probe Lithium phthalocyanine (LiPc) allows for incorporation of probe particulates into spheroid during its formation. Spectra signal strength after incorporation of probe into spheroid indicated that a volume of 20 μl of probe (stock solution: 0.10 mg/mL) is sufficient to provide a strong spectra across a range of spheroid sizes. The addition of non-toxic probes (that do not produce or consume oxygen) report on oxygen diffusion throughout the spheroid as a function of size. We provide evidence supporting the use of this model over a range of initial cell seeding densities and spheroid sizes with the production of oxygen distribution as a function of these parameters. In our spheroid model, lower cell seeding densities (∼2,500 cells/spheroid) and absolute size (118±32 μm) allow control of factors such as pre-existing stresses (e.g. ∼ 2% normoxic/hypoxic interface) for more accurate measurement of treatment response. The applied methodology provides an elegant, widely applicable approach to directly characterize spheroid (and other organoid) cultures in biomedical and toxicological research.

Obstructive Sleep Apnea in Obese Hospitalized Patients: A Single Center Experience

PubMed Central

Sharma, Sunil; Mather, Paul J.; Efird, Jimmy T.; Kahn, Daron; Shiue, Kristin Y.; Cheema, Mohammed; Malloy, Raymond; Quan, Stuart F.

2015-01-01

Study Objectives: Obstructive sleep apnea (OSA) is an important health problem associated with significant morbidity and mortality. This condition often is underrecognized in hospitalized patients. The aim of this study was to conduct a clinical pathway evaluation (CPE) among obese patients admitted to a tertiary care hospital. We also assessed oxygen desaturation index (ODI, measured by overnight pulse oximetry) as a potential low-cost screening tool for identifying OSA. Methods: This was a prospective study of 754 patients admitted to an academic medical center between February 2013 and February 2014. Consecutive obese patients (body mass index ≥ 30) admitted to the hospital (medical services) were screened and evaluated for OSA with the snoring, tiredness during daytime, observed apnea, high blood pressure (STOP) questionnaire. The admitting team was advised to perform follow-up evaluation, including polysomnography, if the test was positive. Results: A total of 636 patients were classified as high risk and 118 as low risk for OSA. Within 4 w of discharge, 149 patients underwent polysomnography, and of these, 87% (129) were shown to have OSA. An optimal screening cutoff point for OSA (apnea-hypopnea index ≥ 10/h) was determined to be ODI ≥ 10/h [Matthews correlation coefficient = 0.36, 95% confidence interval = 0.24–0.47]. Significantly more hospitalized patients were identified and underwent polysomnography compared with the year prior to introduction of the CPE. Conclusions: Our results indicate that the CPE increased the identification of OSA in this population. Furthermore, ODI derived from overnight pulse oximetry may be a cost-effective strategy to screen for OSA in hospitalized patients. Citation: Sharma S, Mather PJ, Efird JT, Kahn D, Shiue KY, Cheema M, Malloy R, Quan SF. Obstructive sleep apnea in obese hospitalized patients: a single center experience. J Clin Sleep Med 2015;11(7):717–723. PMID:25766715

Oximetry and indications for tracheotomy for amyotrophic lateral sclerosis.

PubMed

Bach, John Robert; Bianchi, Carlo; Aufiero, Elaine

2004-11-01

To explore the use of oximetry as a guide for using respiratory aids and tracheotomy in the treatment of patients with amyotrophic lateral sclerosis (ALS). A retrospective review of all ALS patients presenting to a neuromuscular disease clinic since 1996. Patients who were symptomatic for nocturnal hypoventilation were prescribed noninvasive ventilation (NIV). Patients with assisted cough peak flows of < 300 L/min were prescribed oximeters and access to mechanically assisted coughing (MAC) to prevent or reverse decreases in baseline pulse oximetric saturation (Spo(2)) levels of < 95%. The number of decreases in baseline Spo(2) that could be normalized by any combination of NIV and MAC and the duration of normalization were recorded. When the baseline was not or could not be normalized, the time to acute respiratory failure and tracheotomy or death were recorded. Twenty-five patients became dependent on NIV, including 13 patients who received NIV continuously for a mean (+/- SD) period of 19.7 +/- 16.9 months, without desaturation (group 1). For another 76 patients, the daytime baseline Spo(2) level decreased to < 95% 78 times. For 41 patients, the baseline level was corrected by NIV/MAC (group 2) for a mean duration of 11.1 +/- 8.7 months before desaturation reoccurred for 27 patients. Of the latter patients, 11 underwent tracheotomy, 14 died in < 2 months, and 2 had their condition again corrected by the addition of MAC therapy. For 35 patients, the desaturation was not or could not be normalized (group 3). Thirty-three of these 35 patients required tracheotomy or died within 2 months. The only significant difference between groups 1 and 2 and group 3 was significantly poorer glottic function in the patients in group 3. Tracheotomy or death is highly likely within 2 months of a decrease in baseline Spo(2) that cannot be corrected by NIV or MAC. The long-term use of NIV and MAC, and the avoidance of tracheotomy is dependent on glottic function rather than on inspiratory or expiratory muscle failure.

Emergency Department Vital Signs and Outcomes After Discharge.

PubMed

Gabayan, Gelareh Z; Gould, Michael K; Weiss, Robert E; Derose, Stephen F; Chiu, Vicki Y; Sarkisian, Catherine A

2017-07-01

Vital signs are critical markers of illness severity in the emergency department (ED). Providers need to understand the abnormal vital signs in older adults that are problematic. We hypothesized that in patients age > 65 years discharged from the ED, there are abnormal vital signs that are associated with an admission to an inpatient bed within 7 days of discharge. We conducted a retrospective cohort study using data from a regional integrated health system of members age > 65 years during the years 2009 to 2010. We used univariate contingency tables to assess the relationship between hospital admission within 7 days of discharge and vital sign (including systolic blood pressure [sBP], heart rate [HR], body temperature, and pulse oximetry [SpO 2 ] values measured closest to discharge) using standard thresholds for abnormal and thresholds derived from the study data. Of 104,025 ED discharges, 4,638 (4.5%) were followed by inpatient admission within 7 days. Vital signs had a greater odds of admission beyond a single cutoff. The vital signs with at least twice the odds of admission were sBP < 97 mm Hg (odds ratio [OR] = 2.02, 95% CI = 1.57-2.60), HR > 101 beats/min (OR = 2.00 95% CI = 1.75-2.29), body temperature > 37.3°C (OR = 2.14, 95% CI = 1.90-2.41), and pulse oximetry < 92 SpO 2 (OR = 2.04, 95% CI = 1.55-2.68). Patients with two vital sign abnormalities per the analysis had the highest odds of admission. A majority of patients discharged with abnormal vital signs per the analysis were not admitted within 7 days of ED discharge. While we found a majority of patients discharged with abnormal vital signs as defined by the analysis, not to be admitted after discharge, we identified vital signs associated with at least twice the odds of admission. © 2017 by the Society for Academic Emergency Medicine.

Detection of sleep disordered breathing and its central/obstructive character using nasal cannula and finger pulse oximeter.

PubMed

Sommermeyer, Dirk; Zou, Ding; Grote, Ludger; Hedner, Jan

2012-10-15

To assess the accuracy of novel algorithms using an oximeter-based finger plethysmographic signal in combination with a nasal cannula for the detection and differentiation of central and obstructive apneas. The validity of single pulse oximetry to detect respiratory disturbance events was also studied. Patients recruited from four sleep laboratories underwent an ambulatory overnight cardiorespiratory polygraphy recording. The nasal flow and photoplethysmographic signals of the recording were analyzed by automated algorithms. The apnea hypopnea index (AHI(auto)) was calculated using both signals, and a respiratory disturbance index (RDI(auto)) was calculated from photoplethysmography alone. Apnea events were classified into obstructive and central types using the oximeter derived pulse wave signal and compared with manual scoring. Sixty-six subjects (42 males, age 54 ± 14 yrs, body mass index 28.5 ± 5.9 kg/m(2)) were included in the analysis. AHI(manual) (19.4 ± 18.5 events/h) correlated highly significantly with AHI(auto) (19.9 ± 16.5 events/h) and RDI(auto) (20.4 ± 17.2 events/h); the correlation coefficients were r = 0.94 and 0.95, respectively (p < 0.001) with a mean difference of -0.5 ± 6.6 and -1.0 ± 6.1 events/h. The automatic analysis of AHI(auto) and RDI(auto) detected sleep apnea (cutoff AHI(manual) ≥ 15 events/h) with a sensitivity/specificity of 0.90/0.97 and 0.86/0.94, respectively. The automated obstructive/central apnea indices correlated closely with manually scoring (r = 0.87 and 0.95, p < 0.001) with mean difference of -4.3 ± 7.9 and 0.3 ± 1.5 events/h, respectively. Automatic analysis based on routine pulse oximetry alone may be used to detect sleep disordered breathing with accuracy. In addition, the combination of photoplethysmographic signals with a nasal flow signal provides an accurate distinction between obstructive and central apneic events during sleep.

Improved accuracy of methemoglobin detection by pulse CO-oximetry during hypoxia.

PubMed

Feiner, John R; Bickler, Philip E

2010-11-01

Methemoglobin in the blood cannot be detected by conventional pulse oximetry and may bias the oximeter's estimate (Spo(2)) of the true arterial functional oxygen saturation (Sao(2)). A recently introduced "pulse CO-oximeter" (Masimo Rainbow SET® Radical-7) that measures SpMet, a noninvasive measurement of the percentage of methemoglobin in arterial blood (%MetHb), was shown to read spuriously high values during hypoxia. In this study we sought to determine whether the manufacturer's modifications have improved the device's ability to detect and accurately measure methemoglobin and deoxyhemoglobin simultaneously. Twelve healthy adult volunteer subjects were fitted with sensors on the middle finger of each hand, and a radial arterial catheter was placed for blood sampling. Intravenous administration of ∼300 mg of sodium nitrite elevated subjects' methemoglobin levels to a 7% to 11% target level, and hypoxia was induced to different levels of Sao(2) (70% to 100%) by varying fractional inspired oxygen. Pulse CO-oximeter readings were compared with arterial blood values measured with a Radiometer ABL800 FLEX multi-wavelength oximeter. Pulse CO-oximeter methemoglobin reading performance was analyzed by the bias (SpMet-%MetHb), and by observing the incidence of meaningful reading errors and predictive value at the various hypoxia levels. Spo(2) bias (Spo(2)--Sao(2)), precision, and root-mean-square error were evaluated during conditions of elevated methemoglobin. Observations spanned 74% to 100% Sao(2) and 0.4% to 14.4% methemoglobin with 307 blood draws and 602 values from the 2 oximeters. Masimo methemoglobin reading bias and precision over the full Sao(2) span was 0.16% and 0.83%, respectively, and was similar across the span. Masimo Spo(2) readings were biased -1.93% across the 70% to 100% Sao(2) range. The Rainbow's methemoglobin readings are acceptably accurate over an oxygen saturation range of 74%-100% and a methemoglobin range of 0%-14%.

In vivo mapping of tumor oxygen consumption using (19)F MRI relaxometry.

PubMed

Diepart, Caroline; Magat, Julie; Jordan, Bénédicte F; Gallez, Bernard

2011-06-01

Recently, we have developed a new electron paramagnetic resonance (EPR) protocol in order to estimate tissue oxygen consumption in vivo. Because it is crucial to probe the heterogeneity of response in tumors, the aim of this study was to apply our protocol, together with (19)F MRI relaxometry, to the mapping of the oxygen consumption in tumors. The protocol includes the continuous measurement of tumor po(2) during the following respiratory challenge: (i) basal values during air breathing; (ii) increasing po(2) values during carbogen breathing until saturation of tissue with oxygen; (iii) switching back to air breathing. We have demonstrated previously using EPR oximetry that the kinetics of return to the basal value after oxygen saturation are mainly governed by tissue oxygen consumption. This challenge was applied in hyperthyroid mice (generated by chronic treatment with L-thyroxine) and control mice, as hyperthyroidism is known to dramatically affect the oxygen consumption rate of tumor cells. Our recently developed snapshot inversion recovery MRI fluorocarbon oximetry technique allowed the po(2) return kinetics to be measured with a high temporal resolution. The kinetic constants (i.e. oxygen consumption rates) were higher for tumors from hyperthyroid mice than from control mice, data that are consistent with our previous EPR study. The corresponding histograms of the (19)F MRI data showed that the kinetic constants displayed a shift to the right for the hyperthyroid group, indicating a higher oxygen consumption in these tumors. The color maps showed a large heterogeneity in terms of oxygen consumption rate within a tumor. In conclusion, (19)F MRI relaxometry allows the noninvasive mapping of the oxygen consumption in tumors. The ability to assess the heterogeneity of tumor response is critical in order to identify potential tumor regions that might be resistant to treatment and therefore produce a poor response to therapy. Copyright © 2010 John Wiley & Sons, Ltd.

Shortening the Feedback Loop for Sleep Apnea Patients Via a Wireless Blood Pulse-Oximetry System

PubMed Central

Stepnowsky, Carl; Blair, Paul; DiNicola, Gia; Lenert, Leslie A

2006-01-01

Much of the clinical care of sleep apnea patients is focused on case identification, diagnosis, and treatment prescription, while follow-up care tends to be intermittent and patient-initiated. There is a clear need for an alternative, cost-effective way to examine sleep apnea treatment efficacy. As part of our research program to improve the clinical care of sleep apnea patients using Internet enabled systems, we have developed a prototype Wireless Blood Pulse-Oximeter System that patients can use in their homes. The oximeter system can be applied by the patient and is based on a data-push mechanism to a secure server that is designed for both patient and provider access. PMID:17238730

The estimation of recovery time of calf muscle oxygen saturation during exercise by using functional near infrared spectroscopy

NASA Astrophysics Data System (ADS)

Ansari, M. A.; Shojaeifar, M.; Mohajerani, E.

2014-08-01

Several methods of near infrared spectroscopy such as functional near infrared spectroscopy (fNIRS) and pulse oximetry have been applied for monitoring of tissue oxygenation or arterial oxygen saturation. Some vascular diseases can be diagnosed through measurements of tissue oxygenation. In this study, the temporal variation of oxygenation of calf muscle after exercise is studied by fNIRS. First, the accuracy of a low-cost fNIRS system is studied by measuring the oxygenation of a lipid phantom. Moreover, in-vivo study is performed to evaluate the precision of this system. Then, the variation of muscle oxygenation of four persons during exercise is measured and also the recovery time after walking/running is measured by this fNIRS system.

Cerebral Palsy Gait, Clinical Importance

PubMed Central

TUGUI, Raluca Dana; ANTONESCU, Dinu

2013-01-01

ABSTRACT Cerebral palsy refers to a lesion on an immature brain, that determines permanent neurological disorders. Knowing the exact cause of the disease does not alter the treatment management. The etiology is 2-2.5/1000 births and the rate is constant in the last 40-50 years because advances in medical technologies have permitted the survival of smaller and premature new born children. Gait analysis has four directions: kinematics (represents body movements analysis without calculating the forces), kinetics (represents body moments and forces), energy consumption (measured by oximetry), and neuromuscular activity (measured by EMG). Gait analysis can observe specific deviations in a patient, allowing us to be more accurate in motor diagnoses and treatment solutions: surgery intervention, botulinum toxin injection, use of orthosis, physical kinetic therapy, oral medications, baclofen pump. PMID:24790675

A rare side effect of transesophageal echocardiography: methemoglobinemia from topical benzocaine anesthesia.

PubMed

Jaffery, Zehra; Ananthasubramaniam, Karthik

2008-03-01

Benzocaine induced methemoglobinemia is an uncommon, potentially fatal condition. A 44-year-old woman with a history of hepatitis C and intravenous drug use was referred for transesophageal echocardiography for bacteremia evaluation. During induction of topical anesthesia with benzocaine spray she became cyanotic. Pulse oximetry revealed marked desaturation (75%) but was discordant from arterial blood O(2) saturation (99%). Due to clinical suspicion, methemoglobin level was measured and noted to be 69%. The patient was treated with 2 mg/kg of methylene blue intravenously with resolution of her symptoms. Physicians using topical anesthesia in endoscopic suites should be aware of this rare, potentially life-threatening treatable condition. High clinical suspicion and availability of methylene blue in endoscopy suites will facilitate prompt diagnosis and treatment.

A Case Report of Benzocaine-Induced Methemoglobinemia.

PubMed

Sewell, Chaundra R; Rivey, Michael P

2017-01-01

Methemoglobinemia is a serious medical condition characterized by the disrupted binding of oxygen to iron on hemoglobin, with a consequent impaired oxygen delivery to body tissues. Various drugs including the local anesthetics such as benzocaine can cause acquired methemoglobinemia. The reported case describes methemoglobinemia that occurred in association with the use of topical benzocaine spray and lozenges in a previously healthy 51-year-old female who had undergone colon surgery to remove a bleeding polyp. Pulse oximetry revealed the patient was hypoxic and a measured methemoglobin (MetHB) serum concentration was 32.4%, well above the normal of less than 2%. Treatment with intravenous methylene blue resulted in a rapid improvement in the patient's respiratory status. The case emphasizes the need for practitioners to appreciate that topical benzocaine products can cause potentially fatal methemoglobinemia.

Heart Rate and Electrocardiography Monitoring in Mice

PubMed Central

Ho, David; Zhao, Xin; Gao, Shumin; Hong, Chull; Vatner, Dorothy E.; Vatner, Stephen F.

2011-01-01

The majority of current cardiovascular research involves studies in genetically engineered mouse models. The measurement of heart rate is central to understanding cardiovascular control under normal conditions, with altered autonomic tone, superimposed stress or disease states, both in wild type mice as well as those with altered genes. Electrocardiography (ECG) is the “gold standard” using either hard wire or telemetry transmission. In addition, heart rate is measured or monitored from the frequency of the arterial pressure pulse or cardiac contraction, or by pulse oximetry. For each of these techniques, discussions of materials and methods, as well as advantages and limitations are covered. However, only the direct ECG monitoring will determine not only the precise heart rates but also whether the cardiac rhythm is normal or not. PMID:21743842

Factors Determining the Oxygen Permeability of Biological Membranes: Oxygen Transport Across Eye Lens Fiber-Cell Plasma Membranes.

PubMed

Subczynski, Witold Karol; Widomska, Justyna; Mainali, Laxman

2017-01-01

Electron paramagnetic resonance (EPR) spin-label oximetry allows the oxygen permeability coefficient to be evaluated across homogeneous lipid bilayer membranes and, in some cases, across coexisting membrane domains without their physical separation. The most pronounced effect on oxygen permeability is observed for cholesterol, which additionally induces the formation of membrane domains. In intact biological membranes, integral proteins induce the formation of boundary and trapped lipid domains with a low oxygen permeability. The effective oxygen permeability coefficient across the intact biological membrane is affected not only by the oxygen permeability coefficients evaluated for each lipid domain but also by the surface area occupied by these domains in the membrane. All these factors observed in fiber cell plasma membranes of clear human eye lenses are reviewed here.

Solid hemoglobin-polymer phantoms for evaluation of biophotonic systems.

PubMed

Jang, Hyounguk; Pfefer, T Joshua; Chen, Yu

2015-09-15

Stable tissue phantoms that incorporate the spectral absorption properties of hemoglobin would benefit a wide range of biophotonic technologies. Toward this end, we have developed and validated a novel polymer material incorporating hemoglobin. Our solid hemoglobin-polymer (SHP) material is fabricated by mixing liquid silicone base with a hemoglobin solution, followed by sonication and low temperature curing. The optical properties of samples were determined over 450-1000 nm using the inverse adding-doubling method and the Beer-Lambert law. Measurements indicated SHP optical stability over four months. Near-infrared spectroscopy and hyperspectral imaging measurements of SHP samples were performed to demonstrate the utility of this approach. SHP materials have the potential to improve tissue-simulating phantoms used for development, evaluation, and standardization of optical devices for oximetry and other applications.

Characteristics of Alpha-1 Antitrypsin-Deficient Individuals in the Long-term Oxygen Treatment Trial and Comparison with Other Subjects with Chronic Obstructive Pulmonary Disease.

PubMed

Stoller, James K; Aboussouan, Loutfi S; Kanner, Richard E; Wilson, Laura A; Diaz, Phil; Wise, Robert

2015-12-01

Alpha-1 antitrypsin deficiency (AATD) predisposes to chronic obstructive pulmonary disease, but is underrecognized. Oxygenation and exercise desaturation in individuals with AATD-associated chronic obstructive pulmonary disease has been sparsely studied. The Long-term Oxygen Treatment Trial (LOTT) permits comparing these features of individuals with AATD with alpha-1 antitrypsin-replete (called "usual chronic obstructive pulmonary disease") LOTT participants. Compare demographic, clinical, baseline oxygenation, and exercise desaturation features in participating AATD subjects with those of other LOTT subjects. LOTT is a multicenter randomized controlled trial comparing use of supplemental oxygen versus not in subjects with chronic obstructive pulmonary disease and moderate hypoxemia (resting oxygen saturation as measured by pulse oximetry, 89-93%) or normal oxygen saturation at rest and significant exercise desaturation. Among the 597 LOTT participants with nonmissing alpha-1 antitrypsin levels, 11 (1.8%) had severe AATD and 44 (7.4%) had mild/moderate AATD. Comparison of the 11 severely AAT-deficient individuals with the 542 LOTT participants with usual chronic obstructive pulmonary disease showed that the AATD subjects were younger and despite less smoking, had lower FEV1/FVC (mean post-bronchodilator FEV1/FVC, 0.38 ± 0.06 vs. 0.46 ± 0.13; P = 0.002). Comparison with 27 age-, sex-, and FEV1-matched alpha-1 antitrypsin-normal LOTT participants showed no baseline difference in resting room air pulse oximetry saturation (AATD, 93.6% ± 2.3% vs. 92.7% ± 2.2%; P = 0.64). Exercise-related desaturation was more severe in the individuals with AATD based on desaturation to 88% or less sooner during a 6-minute-walk test, having a higher percentage of desaturation points (e.g., <90%) during exercise, and having a higher distance-saturation product (defined as the distance walked in 6 min multiplied by the nadir saturation achieved during the 6-minute-walk test). These data suggest that individuals with AATD experience more profound desaturation with exercise than age-, sex-, race-, and FEV1-matched control subjects with usual chronic obstructive pulmonary disease. Clinical trial registered with www.clinicaltrials.gov (NCT 00692198).

An Observational Assessment of Anesthesia Capacity in Madagascar as a Prerequisite to the Development of a National Surgical Plan.

PubMed

Baxter, Linden S; Ravelojaona, Vaonandianina A; Rakotoarison, Hasiniaina N; Herbert, Alison; Bruno, Emily; Close, Kristin L; Andean, Vanessa; Andriamanjato, Hery H; Shrime, Mark G; White, Michelle C

2017-06-01

The global lack of anesthesia capacity is well described, but country-specific data are needed to provide country-specific solutions. We aimed to assess anesthesia capacity in Madagascar as part of the development of a Ministry of Health national surgical plan. As part of a nationwide surgical safety quality improvement project, we surveyed 19 of 22 regional hospitals, representing surgical facilities caring for 75% of the total population. The assessment was divided into 3 areas: anesthesia workforce density, infrastructure and equipment, and medications. Data were obtained by semistructured interviews with Ministry of Health officials, hospital directors, technical directors, statisticians, pharmacists, and anesthesia providers and through on-site observations. Interview questions were adapted from the World Health Organization Situational Analysis Tool and the World Federation of Societies of Anaesthesiologists International Standards for Safe Practice of Anaesthesia. Additional data on workforce density were collected from the 3 remaining regions so that workforce density data are representative of all 22 regions. Anesthesia physician workforce density is 0.26 per 100,000 population and 0.19 per 100,000 outside of the capital region. Less than 50% of hospitals surveyed reported having a reliable electricity and oxygen supply. The majority of anesthesia providers work without pulse oximetry (52%) or a functioning vaporizer (52%). All the hospitals surveyed had very basic pediatric supplies, and none had a pediatric pulse oximetry probe. Ketamine is universally available but more than 50% of hospitals lack access to opioids. None of the 19 regional hospitals surveyed was able to completely meet the World Federation of Societies of Anaesthesiologists' standards for monitoring. Improving anesthesia care is complex. Capacity assessment is a first step that would enable progress to be tracked against specific targets. In Madagascar, scale-up of the anesthesia workforce, investment in infrastructure and equipment, and improvement in medication supply-chain management are needed to attain minimal international standards. Data from this study were presented to the Ministry of Health for inclusion in the development of a national surgical plan, together with recommendations for the needed improvements in the delivery of anesthesia.

Exchange transfusion can be life-saving in severe propanil poisoning: a case report.

PubMed

Ranasinghe, Priyanga; Dilrukshi, Shani Apsara; Atukorala, Inoshi; Katulanda, Prasad; Gnanathasan, Ariaranee

2014-10-08

Propanil is an important cause of herbicide poisoning in Sri Lanka, accounting for about 2% of all cases of self-poisoning. The outcome is extremely poor when the poisoning is severe and current medical care is of limited efficacy. Death usually occurs due to the severe and prolonged methaemoglobinaemia. We describe a case of severe Propanil poisoning, successfully treated by exchange transfusion at a tertiary care hospital in Sri Lanka. A 17-year old Sri Lankan male (body weight--42 kg), presented to a local hospital 1 hour after self-ingestion of nearly 500 ml (4.3 g/kg) of liquid Propanil (concentration--360 g/l). On admission he had dizziness and peripheral cyanosis. He was given intravenous methylene blue (1 mg/kg) within one hour of admission, which was repeated subsequently due to minimal response. The next day morning, (18 hours after poisoning) the patient was transferred to the National Hospital of Sri Lanka (NHSL) for further management. On admission to NHSL, he was drowsy and confused, had a shallow respiratory effort and marked central and peripheral cyanosis. Respiratory rate was 20/min, with a pulse-oximetry of 77% on room air. The arterial blood gas analysis was as follows; pH--7.24, HCO3(-)--12 mmol/l, pCO2--28 mmHg, pO2--239 mmHg and O2 saturation--100%. Exchange transfusion was commenced within two hours of admission to NHSL. A dramatic improvement in oxygen saturation was observed immediately afterwards, with the saturation in pulse-oximetry rising to >95%. The level of consciousness and respiratory effort also improved. He was discharged subsequently 8 days after the initial poisoning. Propanil has potential to produce severe life threatening clinical manifestations, despite categorization as a herbicide with low toxicity. In cases of severe poisoning, exchange transfusion may be life saving. Since methylene blue, intensive care and exchange transfusion facilities are also not readily available in local hospitals, which frequently encounter cases of severe Propanil poisoning, early transfer of patients to tertiary care hospitals should be considered. Exchange transfusion may be helpful even in late stages in patients with severe poisoning.

Variability in Usual Care Mechanical Ventilation for Pediatric Acute Respiratory Distress Syndrome: Time for a Decision Support Protocol?

PubMed

Newth, Christopher J L; Sward, Katherine A; Khemani, Robinder G; Page, Kent; Meert, Kathleen L; Carcillo, Joseph A; Shanley, Thomas P; Moler, Frank W; Pollack, Murray M; Dalton, Heidi J; Wessel, David L; Berger, John T; Berg, Robert A; Harrison, Rick E; Holubkov, Richard; Doctor, Allan; Dean, J Michael; Jenkins, Tammara L; Nicholson, Carol E

2017-11-01

Although pediatric intensivists philosophically embrace lung protective ventilation for acute lung injury and acute respiratory distress syndrome, we hypothesized that ventilator management varies. We assessed ventilator management by evaluating changes to ventilator settings in response to blood gases, pulse oximetry, or end-tidal CO2. We also assessed the potential impact that a pediatric mechanical ventilation protocol adapted from National Heart Lung and Blood Institute acute respiratory distress syndrome network protocols could have on reducing variability by comparing actual changes in ventilator settings to those recommended by the protocol. Prospective observational study. Eight tertiary care U.S. PICUs, October 2011 to April 2012. One hundred twenty patients (age range 17 d to 18 yr) with acute lung injury/acute respiratory distress syndrome. Two thousand hundred arterial and capillary blood gases, 3,964 oxygen saturation by pulse oximetry, and 2,757 end-tidal CO2 values were associated with 3,983 ventilator settings. Ventilation mode at study onset was pressure control 60%, volume control 19%, pressure-regulated volume control 18%, and high-frequency oscillatory ventilation 3%. Clinicians changed FIO2 by ±5 or ±10% increments every 8 hours. Positive end-expiratory pressure was limited at ~10 cm H2O as oxygenation worsened, lower than would have been recommended by the protocol. In the first 72 hours of mechanical ventilation, maximum tidal volume/kg using predicted versus actual body weight was 10.3 (8.5-12.9) (median [interquartile range]) versus 9.2 mL/kg (7.6-12.0) (p < 0.001). Intensivists made changes similar to protocol recommendations 29% of the time, opposite to the protocol's recommendation 12% of the time and no changes 56% of the time. Ventilator management varies substantially in children with acute respiratory distress syndrome. Opportunities exist to minimize variability and potentially injurious ventilator settings by using a pediatric mechanical ventilation protocol offering adequately explicit instructions for given clinical situations. An accepted protocol could also reduce confounding by mechanical ventilation management in a clinical trial.

In vitro assessment of the structure-activity relationship of tyrosinase-dependent cytotoxicity of a series of substituted phenols.

PubMed

Naish-Byfield, S; Cooksey, C J; Latter, A M; Johnson, C I; Riley, P A

1991-01-01

The rate of oxidation by purified mushroom tyrosinase of 30 compounds was measured by oximetry, and the tyrosinase-dependent cytotoxicity of each estimated in an in vitro assay using exposure of non-melanogenic cells to the agents in the presence and absence of tyrosinase. Cytotoxicity was estimated by immediate inhibition of DNA synthesis; 4-hydroxyanisole was used as the reference material. Compounds that were not oxidized by tyrosinase were found to be non-toxic but there was no direct relationship between the rate of oxidation and the relative cytotoxicity of those materials that acted as substrates for the enzyme. Thioethers were found to be more cytotoxic than the corresponding phenoxyethers. This was partly due to their greater rate of oxidation by tyrosinase and, in the case of propylthiophenol, the consequence of higher effective toxicity of the lipophilic species. The optimum chain length for the side chain of the oxyethers was three saturated carbon atoms and the toxicity appeared to be influenced by the lipophilicity of the compounds, possibly reflecting the relative lipid solubility of the putative toxic ortho-quinones generated from them. The maximum tyrosinase-dependent toxicity observed was in the range 5-6 times the relative toxicity of 4-hydroxyanisole. Sulphinyl and sulphonyl derivatives were inactive. In addition to oxyethers and thioethers, esters and glycosides of oxyethers were also examined and were found to be toxic in the presence of tyrosinase when hydrolysed. The succinates were found to be oxidized and toxic in our test system, suggesting that they rapidly underwent spontaneous hydrolysis. Oximetry data suggest that slight spontaneous hydrolysis of the other compounds occurs but they were not toxic in our assay. Ring-methylated phenoxyethers were oxidized relatively slowly and were non-toxic. Fluorine-substituted phenoxyethers were oxidized slightly more rapidly and exhibited clear toxicity in our system. Sesamol was oxidized to a black pigment but was non-toxic in our assay. A water-soluble vitamin E derivative was not oxidized and was non-toxic. Allyl hydroquinone was not oxidized but exhibited significant direct toxicity.

Cardiopulmonary complications during pediatric seizures: A prelude to understanding SUDEP

PubMed Central

Singh, Kanwaljit; Katz, Eliot S.; Zarowski, Marcin; Loddenkemper, Tobias; Llewellyn, Nichelle; Manganaro, Sheryl; Gregas, Matt; Pavlova, Milena; Kothare, Sanjeev V.

2017-01-01

Summary Purpose Sudden unexpected death in epilepsy (SUDEP) is an important, unexplained cause of death in epilepsy. Role of cardiopulmonary abnormalities in the pathophysiology of SUDEP is unclear in the pediatric population. Our objective was to assess cardiopulmonary abnormalities during epileptic seizures in children, with the long-term goal of identifying potential mechanisms of SUDEP. Methods We prospectively recorded cardiopulmonary functions using pulse-oximetry, electrocardiography (ECG), and respiratory inductance plethysmography (RIP). Logistic regression was used to evaluate association of cardiorespiratory findings with seizure characteristics and demographics. Key Findings We recorded 101 seizures in 26 children (average age 3.9 years). RIP provided analyzable data in 78% and pulse-oximetry in 63% seizures. Ictal central apnea was more prevalent in patients with younger age (p = 0.01), temporal lobe (p < 0.001), left-sided (p < 0.01), symptomatic generalized (p = 0.01), longer duration seizures (p < 0.0002), desaturation (p < 0.0001), ictal bradycardia (p < 0.05), and more antiepileptic drugs (AEDs; p < 0.01), and was less prevalent in frontal lobe seizures (p < 0.01). Ictal bradypnea was more prevalent in left-sided (p < 0.05), symptomatic generalized seizures (p < 0.01), and in brain magnetic resonance imaging (MRI) lesions (p < 0.1). Ictal tachypnea was more prevalent in older-age (p = 0.01), female gender (p = 0.05), frontal lobe (p < 0.05), right-sided seizures (p < 0.001), fewer AEDs (p < 0.01), and less prevalent in lesional (p < 0.05) and symptomatic generalized seizures (p < 0.05). Ictal bradycardia was more prevalent in male patients (p < 0.05) longer duration seizures (p < 0.05), desaturation (p = 0.001), and more AEDs (p < 0.05), and was less prevalent in frontal lobe seizures (p = 0.01). Ictal and postictal bradycardia were directly associated (p < 0.05). Desaturation was more prevalent in longer-duration seizures (p < 0.0001), ictal apnea (p < 0.0001), ictal bradycardia (p = 0.001), and more AEDs (p = 0.001). Significance Potentially life-threatening cardiopulmonary abnormalities such as bradycardia, apnea, and hypoxemia in pediatric epileptic seizures are associated with predictable patient and seizure characteristics, including seizure subtype and duration. PMID:23731396

Sleep Overnight Monitoring for Apnea in Patients Hospitalized with Heart Failure (SOMA-HF Study)

PubMed Central

Sharma, Sunil; Mather, Paul J.; Chowdhury, Anindita; Gupta, Suchita; Mukhtar, Umer; Willes, Leslee; Whellan, David J.; Malhotra, Atul; Quan, Stuart F.

2017-01-01

Introduction: Sleep-disordered breathing (SDB) is highly prevalent in hospitalized patients with congestive heart failure (CHF) and the condition is diagnosed and treated in only a minority of these patients. Portable monitoring (PM) is a screening option, but due to costs and the expertise required, many hospitals may find it impractical to implement. We sought to test the utility of an alternative approach for screening hospitalized CHF patients for SDB, high-resolution pulse oximetry (HRPO). Methods: We conducted a prospective controlled trial of 125 consecutive patients admitted to the hospital with CHF. Simultaneous PM and HRPO for a single night was performed. All but one patient were monitored on breathing room air. The HRPO-derived ODI (oxygen desaturation index) was compared with PM-derived respiratory event index (REI) using both receiver operator characteristic (ROC) curve analysis and a Bland-Altman plot. Results: Of 105 consecutive CHF patients with analyzable data, 61 (58%) were males with mean age of 64.9 ± 15.1 years and mean body mass index of 30.3 ± 8.3 kg/m2. Of the 105 patients, 10 (9.5%) had predominantly central sleep apnea (central events > 50% of the total events), although central events were noted in 42 (40%) of the patients. The ROC analysis showed an area under the curve of 0.89 for REI > 5 events/h. The Bland-Altman plot showed acceptable agreement with 95% limits of agreement between −28.5 to 33.7 events/h and little bias. Conclusions: We conclude that high-resolution pulse oximetry is a simple and cost-effective screening tool for SDB in CHF patients admitted to the hospital. Such screening approaches may be valuable for large-scale implementation and for the optimal design of interventional trials. Citation: Sharma S, Mather PJ, Chowdhury A, Gupta S, Mukhtar U, Willes L, Whellan DJ, Malhotra A, Quan SF. Sleep overnight monitoring for apnea in patients hospitalized with heart failure (SOMA-HF Study). J Clin Sleep Med. 2017;13(10):1185–1190. PMID:28859720

Monitoring of cerebral oxygen saturation during resuscitation in out-of-hospital cardiac arrest: a feasibility study in a physician staffed emergency medical system.

PubMed

Schewe, Jens-Christian; Thudium, Marcus O; Kappler, Jochen; Steinhagen, Folkert; Eichhorn, Lars; Erdfelder, Felix; Heister, Ulrich; Ellerkmann, Richard

2014-10-05

Despite recent advances in resuscitation algorithms, neurological injury after cardiac arrest due to cerebral ischemia and reperfusion is one of the reasons for poor neurological outcome. There is currently no adequate means of measuring cerebral perfusion during cardiac arrest. It was the aim of this study to investigate the feasibility of measuring near infrared spectroscopy (NIRS) as a potential surrogate parameter for cerebral perfusion in patients with out-of-hospital resuscitations in a physician-staffed emergency medical service. An emergency physician responding to out-of-hospital emergencies was equipped with a NONIN cerebral oximetry device. Cerebral oximetry values (rSO2) were continuously recorded during resuscitation and transport. Feasibility was defined as >80% of total achieved recording time in relation to intended recording time. 10 patients were prospectively enrolled. In 89.8% of total recording time, rSO2 values could be recorded (213 minutes and 20 seconds), thus meeting feasibility criteria. 3 patients experienced return of spontaneous circulation (ROSC). rSO2 during manual cardiopulmonary resuscitation (CPR) was lower in patients who did not experience ROSC compared to the 3 patients with ROSC (31.6%, ± 7.4 versus 37.2% ± 17.0). ROSC was associated with an increase in rSO2. Decrease of rSO2 indicated occurrence of re-arrest in 2 patients. In 2 patients a mechanical chest compression device was used. rSO2 values during mechanical compression were increased by 12.7% and 19.1% compared to manual compression. NIRS monitoring is feasible during resuscitation of patients with out-of-hospital cardiac arrest and can be a useful tool during resuscitation, leading to an earlier detection of ROSC and re-arrest. Higher initial rSO2 values during CPR seem to be associated with the occurrence of ROSC. The use of mechanical chest compression devices might result in higher rSO2. These findings need to be confirmed by larger studies.

Detection of Sleep Disordered Breathing and Its Central/Obstructive Character Using Nasal Cannula and Finger Pulse Oximeter

PubMed Central

Sommermeyer, Dirk; Zou, Ding; Grote, Ludger; Hedner, Jan

2012-01-01

Study Objective: To assess the accuracy of novel algorithms using an oximeter-based finger plethysmographic signal in combination with a nasal cannula for the detection and differentiation of central and obstructive apneas. The validity of single pulse oximetry to detect respiratory disturbance events was also studied. Methods: Patients recruited from four sleep laboratories underwent an ambulatory overnight cardiorespiratory polygraphy recording. The nasal flow and photoplethysmographic signals of the recording were analyzed by automated algorithms. The apnea hypopnea index (AHIauto) was calculated using both signals, and a respiratory disturbance index (RDIauto) was calculated from photoplethysmography alone. Apnea events were classified into obstructive and central types using the oximeter derived pulse wave signal and compared with manual scoring. Results: Sixty-six subjects (42 males, age 54 ± 14 yrs, body mass index 28.5 ± 5.9 kg/m2) were included in the analysis. AHImanual (19.4 ± 18.5 events/h) correlated highly significantly with AHIauto (19.9 ± 16.5 events/h) and RDIauto (20.4 ± 17.2 events/h); the correlation coefficients were r = 0.94 and 0.95, respectively (p < 0.001) with a mean difference of −0.5 ± 6.6 and −1.0 ± 6.1 events/h. The automatic analysis of AHIauto and RDIauto detected sleep apnea (cutoff AHImanual ≥ 15 events/h) with a sensitivity/specificity of 0.90/0.97 and 0.86/0.94, respectively. The automated obstructive/central apnea indices correlated closely with manually scoring (r = 0.87 and 0.95, p < 0.001) with mean difference of −4.3 ± 7.9 and 0.3 ± 1.5 events/h, respectively. Conclusions: Automatic analysis based on routine pulse oximetry alone may be used to detect sleep disordered breathing with accuracy. In addition, the combination of photoplethysmographic signals with a nasal flow signal provides an accurate distinction between obstructive and central apneic events during sleep. Citation: Sommermeyer D; Zou D; Grote L; Hedner J. Detection of sleep disordered breathing and its central/obstructive character using nasal cannula and finger pulse oximeter. J Clin Sleep Med 2012;8(5):527-533. PMID:23066364

Defining Research Risk in Standard of Care Trials: Lessons from SUPPORT.

PubMed

Press, Joel K; Rogers, Caryn J

2017-04-01

Recent controversy surrounding the Surfactant Positive Airway Pressure and Pulse Oximetry Trial (SUPPORT) and the Office for Human Resource Protection's (OHRP) judgment that its informed consent procedures were inadequate has unmasked considerable confusion about OHRP's definition of research risks. The controversy concerns application of that definition to trials comparing multiple treatments within the existing standard of care. Some have argued that it is impossible for such trials to pose research risks on the grounds that all risks associated with a standard-of-care treatment should instead be considered risks of treatment. However, analysis of OHRP's definition demonstrates that some risks in such trials can be research risks. © The Author 2017. Published by Oxford University Press, on behalf of the Journal of Medicine and Philosophy Inc. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Dental Pulp Testing: A Review

PubMed Central

Chen, Eugene; Abbott, Paul V.

2009-01-01

Dental pulp testing is a useful and essential diagnostic aid in endodontics. Pulp sensibility tests include thermal and electric tests, which extrapolate pulp health from sensory response. Whilst pulp sensibility tests are the most commonly used in clinical practice, they are not without limitations and shortcomings. Pulp vitality tests attempt to examine the presence of pulp blood flow, as this is viewed as a better measure of true health than sensibility. Laser Doppler flowmetry and pulse oximetry are examples of vitality tests. Whilst the prospect is promising, there are still many practical issues that need to be addressed before vitality tests can replace sensibility tests as the standard clinical pulp diagnostic test. With all pulp tests, the results need to be carefully interpreted and closely scrutinised as false results can lead to misdiagnosis which can then lead to incorrect, inappropriate, or unnecessary treatment. PMID:20339575

Sleep architecture in patients with fibromyalgia.

PubMed

Besteiro González, José Luis; Suárez Fernández, Tomás Vicente; Arboleya Rodríguez, Luis; Muñiz, José; Lemos Giráldez, Serafín; Alvarez Fernández, Angel

2011-08-01

The main objective of this work was to evaluate the characteristics of sleep in patients diagnosed with fibromyalgia syndrome. Sleep architecture in 32 patients with fibromyalgia and 20 healthy controls was evaluated. Following the recommendations of the International Federation of Clinical Neurophysiology, polysomnographies were conducted with fibromyalgia patients and the control subjects. The fibromyalgia patients showed alterations in cyclic organization of sleep and an increased number of periodic leg movements associated with cortical arousals. No significant differences were found in respiratory and oximetry variables or in alpha-delta sleep. The results support that fibromyalgia patients present an increase of superficial sleep at the expense of deep sleep and also an increase of periodic leg movements, which could have a pathogenic effect, facilitating the onset of the illness. Lastly, we discuss the results and propose some future lines of research.

Combined multi-distance frequency domain and diffuse correlation spectroscopy system with simultaneous data acquisition and real-time analysis.

PubMed

Carp, Stefan A; Farzam, Parisa; Redes, Norin; Hueber, Dennis M; Franceschini, Maria Angela

2017-09-01

Frequency domain near infrared spectroscopy (FD-NIRS) and diffuse correlation spectroscopy (DCS) have emerged as synergistic techniques for the non-invasive assessment of tissue health. Combining FD-NIRS oximetry with DCS measures of blood flow, the tissue oxygen metabolic rate can be quantified, a parameter more closely linked to underlying physiology and pathology than either NIRS or DCS estimates alone. Here we describe the first commercially available integrated instrument, called the "MetaOx", designed to enable simultaneous FD-NIRS and DCS measurements at rates of 10 + Hz, and offering real-time data evaluation. We show simultaneously acquired characterization data demonstrating performance equivalent to individual devices and sample in vivo measurements of pulsation resolved blood flow, forearm occlusion hemodynamic changes and muscle oxygen metabolic rate monitoring during stationary bike exercise.

Combined multi-distance frequency domain and diffuse correlation spectroscopy system with simultaneous data acquisition and real-time analysis

PubMed Central

Carp, Stefan A.; Farzam, Parisa; Redes, Norin; Hueber, Dennis M.; Franceschini, Maria Angela

2017-01-01

Frequency domain near infrared spectroscopy (FD-NIRS) and diffuse correlation spectroscopy (DCS) have emerged as synergistic techniques for the non-invasive assessment of tissue health. Combining FD-NIRS oximetry with DCS measures of blood flow, the tissue oxygen metabolic rate can be quantified, a parameter more closely linked to underlying physiology and pathology than either NIRS or DCS estimates alone. Here we describe the first commercially available integrated instrument, called the “MetaOx”, designed to enable simultaneous FD-NIRS and DCS measurements at rates of 10 + Hz, and offering real-time data evaluation. We show simultaneously acquired characterization data demonstrating performance equivalent to individual devices and sample in vivo measurements of pulsation resolved blood flow, forearm occlusion hemodynamic changes and muscle oxygen metabolic rate monitoring during stationary bike exercise. PMID:29026684

Postcorrective surgery improvement of nocturnal hypoxemia in a case of partial anomalous pulmonary venous connection and aberrant hepatic vein drainage.

PubMed

Agrawal, Abhinav; Palkar, Atul V; Sahni, Sonu; Vatsia, Sheel K; Shah, Rakesh D; Talwar, Arunabh

2016-01-01

Partial anomalous pulmonary venous connection (PAPVC) is a rare congenital anomaly that leads to an anatomical left-to-right shunt. Termination of the intrahepatic inferior vena cava (IVC) with its azygos continuation associated with the hepatic venous connection to the left atrium (LA) is also a rare congenital anomaly that results in an anatomical right-to-left shunt. A 65-year-old male presented with severe dyspnea on exertion and pedal edema. He was further diagnosed at our clinic and was found to have both the aforementioned congenital abnormalities, creating a bidirectional shunt. On further investigation, he was found to have nocturnal hypoxemia on overnight oximetry. The patient was successfully treated via surgical corrections of the congenital anomalies leading to symptomatic improvement as well as the resolution of nocturnal hypoxemia.

On the Analysis of Fingertip Photoplethysmogram Signals

PubMed Central

Elgendi, Mohamed

2012-01-01

Photoplethysmography (PPG) is used to estimate the skin blood flow using infrared light. Researchers from different domains of science have become increasingly interested in PPG because of its advantages as non-invasive, inexpensive, and convenient diagnostic tool. Traditionally, it measures the oxygen saturation, blood pressure, cardiac output, and for assessing autonomic functions. Moreover, PPG is a promising technique for early screening of various atherosclerotic pathologies and could be helpful for regular GP-assessment but a full understanding of the diagnostic value of the different features is still lacking. Recent studies emphasise the potential information embedded in the PPG waveform signal and it deserves further attention for its possible applications beyond pulse oximetry and heart-rate calculation. Therefore, this overview discusses different types of artifact added to PPG signal, characteristic features of PPG waveform, and existing indexes to evaluate for diagnoses. PMID:22845812

Cerebral autoregulation in the preterm newborn using near-infrared spectroscopy: a comparison of time-domain and frequency-domain analyses

NASA Astrophysics Data System (ADS)

Eriksen, Vibeke R.; Hahn, Gitte H.; Greisen, Gorm

2015-03-01

The aim was to compare two conventional methods used to describe cerebral autoregulation (CA): frequency-domain analysis and time-domain analysis. We measured cerebral oxygenation (as a surrogate for cerebral blood flow) and mean arterial blood pressure (MAP) in 60 preterm infants. In the frequency domain, outcome variables were coherence and gain, whereas the cerebral oximetry index (COx) and the regression coefficient were the outcome variables in the time domain. Correlation between coherence and COx was poor. The disagreement between the two methods was due to the MAP and cerebral oxygenation signals being in counterphase in three cases. High gain and high coherence may arise spuriously when cerebral oxygenation decreases as MAP increases; hence, time-domain analysis appears to be a more robust-and simpler-method to describe CA.

Rugged and breathable forms of stretchable electronics with adherent composite substrates for transcutaneous monitoring.

PubMed

Jang, Kyung-In; Han, Sang Youn; Xu, Sheng; Mathewson, Kyle E; Zhang, Yihui; Jeong, Jae-Woong; Kim, Gwang-Tae; Webb, R Chad; Lee, Jung Woo; Dawidczyk, Thomas J; Kim, Rak Hwan; Song, Young Min; Yeo, Woon-Hong; Kim, Stanley; Cheng, Huanyu; Rhee, Sang Il; Chung, Jeahoon; Kim, Byunggik; Chung, Ha Uk; Lee, Dongjun; Yang, Yiyuan; Cho, Moongee; Gaspar, John G; Carbonari, Ronald; Fabiani, Monica; Gratton, Gabriele; Huang, Yonggang; Rogers, John A

2014-09-03

Research in stretchable electronics involves fundamental scientific topics relevant to applications with importance in human healthcare. Despite significant progress in active components, routes to mechanically robust construction are lacking. Here, we introduce materials and composite designs for thin, breathable, soft electronics that can adhere strongly to the skin, with the ability to be applied and removed hundreds of times without damaging the devices or the skin, even in regions with substantial topography and coverage of hair. The approach combines thin, ultralow modulus, cellular silicone materials with elastic, strain-limiting fabrics, to yield a compliant but rugged platform for stretchable electronics. Theoretical and experimental studies highlight the mechanics of adhesion and elastic deformation. Demonstrations include cutaneous optical, electrical and radio frequency sensors for measuring hydration state, electrophysiological activity, pulse and cerebral oximetry. Multipoint monitoring of a subject in an advanced driving simulator provides a practical example.

Intraoperative detection of methemoglobinemia in a patient given benzocaine spray to relieve discomfort from a nasogastric tube: a case report.

PubMed

Young, Barb

2008-04-01

A 27-year-old man who had 2 admissions 1 month apart for abdominal surgery had a high methemoglobin (MHb) level secondary to liberal use of benzocaine oral spray. A co-oximetry level for MHb of greater than 0.30 proportion of total hemoglobin (30.1%) was detected intraoperatively. The patient was successfully treated with methylene blue intravenously and recovered uneventfully. When the arterial blood gas with a normal partial pressure of oxygen is inconsistent with a low pulse oximeter reading and with the physical appearance of the patient, methemoglobinemia should be considered as a differential diagnosis. This case illustrates the acquired form of methemoglobinemia. Adequate oxygen delivery to the tissues in the body is compromised when MHb overwhelms the capacity of the red blood cells to carry oxygen. If methemoglobinemia is left untreated, it may be fatal.

Frequent Oxygen Desaturation During Sleep on the Day of Bronchoscopy Evaluated by Continuous Pulse Oximeter Monitoring.

PubMed

Chojin, Yasuo; Ishimoto, Hiroshi; Noguchi, Shingo; Kawanami, Toshinori; Kato, Tatsuji; Mukae, Hiroshi; Yatera, Kazuhiro

To perform a bronchoscopy safely, it is very important to make a risk assessment before and after the procedure. There have been no reports of hypoxemia during sleep on the day after a bronchoscopic examination; therefore, we evaluated the oxygen saturation status during sleep on the days before and after bronchoscopy. Thirty patients that underwent bronchoscopy were studied. Continuous pulse oximetry monitoring was performed on the day before bronchoscopy and the day when the bronchoscopy was performed. The average oxygen saturation levels and the oxygen desaturation index (ODI) were evaluated. There was a significant increase (P < 0.05) in the ODI-3% during sleep on the day of the bronchoscopy compared to the day before the bronchoscopy. Clinicians should pay careful attention to hypoxia not only during bronchoscopy, but also during sleep on the night following the procedure.

Specificity of software cooperating with an optoelectronic sensor in the pulse oximeter system

NASA Astrophysics Data System (ADS)

Cysewska-Sobusiak, Anna; Wiczynski, Grzegorz; Jedwabny, Tomasz

1995-06-01

Specificity of a software package composed of two parts which control an optoelectronic sensor of the computer-aided system made to realize the noninvasive measurements of the arterial blood oxygen saturation as well as some parameters of the peripheral pulse waveform, has been described. Principles of the transmission variant of the one and only noninvasive measurement method, so-called pulse oximetry, has been utilized. The software co-ordinates the suitable cooperation of an IBM PC compatible microcomputer with the sensor and one specialized card. This novel card is a key part of the whole measuring system which some application fields are extended in comparison to pulse oximeters commonly attainable. The user-friendly MS Windows graphical environment which creates the system to be multitask and non-preemptive, has been used to design the specific part of the programming presented here. With this environment, sophisticated tasks of the software package can be performed without excessive complication.

Emergency management of fat embolism syndrome

PubMed Central

Shaikh, Nissar

2009-01-01

Fat emboli occur in all patients with long-bone fractures, but only few patients develop systemic dysfunction, particularly the triad of skin, brain, and lung dysfunction known as the fat embolism syndrome (FES). Here we review the FES literature under different subheadings. The incidence of FES varies from 1–29%. The etiology may be traumatic or, rarely, nontraumatic. Various factors increase the incidence of FES. Mechanical and biochemical theories have been proposed for the pathophysiology of FES. The clinical manifestations include respiratory and cerebral dysfunction and a petechial rash. Diagnosis of FES is difficult. The other causes for the above-mentioned organ dysfunction have to be excluded. The clinical criteria along with imaging studies help in diagnosis. FES can be detected early by continuous pulse oximetry in high-risk patients. Treatment of FES is essentially supportive. Medications, including steroids, heparin, alcohol, and dextran, have been found to be ineffective. PMID:19561953

The first experience in estimation of basal cell carcinoma cryoresistence using noninvasive spectrophotometry

NASA Astrophysics Data System (ADS)

Andrukhina, V. V.; Litvinova, K. S.; Nikitin, A. A.; Spiridonova, N. Z.; Rogatkin, D. A.

2009-10-01

The urgency of BCC study affecting maxillofacial area and neck is not only caused by high prevalence of this disease, but also insufficient efficiency of existing treatment methods which lead to full or partial recovery only in 60-80% of cases. We analyzed the results of 198 BCC cases cryosurgical treatment. 33 (16,6%) patients showed continued tumor growth. It has been hypothesized that the behavior and character of microcirculation changes during patient's testing have to correlate with damaging rate of tumors that will allow to develop indications for surgical treatment with local destruction - cryosurgery or cryolaser treatment. We have tested the new group of 33 patients with primary and recurrence types of basal cell carcinoma (BCC) by means of Laser Doppler Flowmetry, Tissues Reflectance Oximetry, Laser Fluorescence Diagnostics before operation. It was shown that the microcirculatory data indicates the presence of cryoresistance.

The first experience in estimation of basal cell carcinoma cryoresistence using noninvasive spectrophotometry

NASA Astrophysics Data System (ADS)

Andrukhina, V. V.; Litvinova, K. S.; Nikitin, A. A.; Spiridonova, N. Z.; Rogatkin, D. A.

2010-02-01

The urgency of BCC study affecting maxillofacial area and neck is not only caused by high prevalence of this disease, but also insufficient efficiency of existing treatment methods which lead to full or partial recovery only in 60-80% of cases. We analyzed the results of 198 BCC cases cryosurgical treatment. 33 (16,6%) patients showed continued tumor growth. It has been hypothesized that the behavior and character of microcirculation changes during patient's testing have to correlate with damaging rate of tumors that will allow to develop indications for surgical treatment with local destruction - cryosurgery or cryolaser treatment. We have tested the new group of 33 patients with primary and recurrence types of basal cell carcinoma (BCC) by means of Laser Doppler Flowmetry, Tissues Reflectance Oximetry, Laser Fluorescence Diagnostics before operation. It was shown that the microcirculatory data indicates the presence of cryoresistance.

Perfluorocarbon-Loaded Lipid Nanocapsules to Assess the Dependence of U87-Human Glioblastoma Tumor pO2 on In Vitro Expansion Conditions

PubMed Central

Lemaire, Laurent; Nel, Janske; Franconi, Florence; Bastiat, Guillaume; Saulnier, Patrick

2016-01-01

Growing tumor cell lines, such as U87-MG glioma cells, under mild hypoxia (3% O2) leads to a ca. 40% reduction in growth rate once implanted in the brain of nude mice, as compared to normoxia (21% O2) grown cells, wherein the former over-express HIF-1 and VEGF-A. Despite developing differently, the tumors have similar: blood perfusion, oxygen consumption, and vascular surface area parameters, whereas the number of blood vessels is nearly doubled in the tumor arising from normoxia cultured cells. Interestingly, tumor oxygen tension, measured using 19F-oximetry, showed that the normoxia grown cells led to tumors characterized by mild hypoxic environment (approximately 4%) conditions, whilst the hypoxia grown cells led to tumors characterized by physioxic environment (approximately 6%) conditions. This reversal in oxygen concentration may be responsible for the apparent paradoxical growth profiles. PMID:27788227

An evaluation of bilateral monitoring of cerebral oxygen saturation during pediatric cardiac surgery.

PubMed

Kussman, Barry D; Wypij, David; DiNardo, James A; Newburger, Jane; Jonas, Richard A; Bartlett, Jodi; McGrath, Ellen; Laussen, Peter C

2005-11-01

Cerebral oximetry is a technique that enables monitoring of regional cerebral oxygenation during cardiac surgery. In this study, we evaluated differences in bi-hemispheric measurement of cerebral oxygen saturation using near-infrared spectroscopy in 62 infants undergoing biventricular repair without aortic arch reconstruction. Left and right regional cerebral oxygen saturation index (rSO2i) were recorded continuously after the induction of anesthesia, and data were analyzed at 12 time points. Baseline rSO2i measurements were left 65 +/- 13 and right 66 +/- 13 (P = 0.17). Mean left and right rSO2i measurements were similar (< or =2 percentage points/absolute scale units) before, during, and after cardiopulmonary bypass, irrespective of the use of deep hypothermic circulatory arrest. Further longitudinal neurological outcome studies are required to determine whether uni- or bi-hemispheric monitoring is required in this patient population.

Rugged and breathable forms of stretchable electronics with adherent composite substrates for transcutaneous monitoring

NASA Astrophysics Data System (ADS)

Jang, Kyung-In; Han, Sang Youn; Xu, Sheng; Mathewson, Kyle E.; Zhang, Yihui; Jeong, Jae-Woong; Kim, Gwang-Tae; Webb, R. Chad; Lee, Jung Woo; Dawidczyk, Thomas J.; Kim, Rak Hwan; Song, Young Min; Yeo, Woon-Hong; Kim, Stanley; Cheng, Huanyu; Rhee, Sang Il; Chung, Jeahoon; Kim, Byunggik; Chung, Ha Uk; Lee, Dongjun; Yang, Yiyuan; Cho, Moongee; Gaspar, John G.; Carbonari, Ronald; Fabiani, Monica; Gratton, Gabriele; Huang, Yonggang; Rogers, John A.

2014-09-01

Research in stretchable electronics involves fundamental scientific topics relevant to applications with importance in human healthcare. Despite significant progress in active components, routes to mechanically robust construction are lacking. Here, we introduce materials and composite designs for thin, breathable, soft electronics that can adhere strongly to the skin, with the ability to be applied and removed hundreds of times without damaging the devices or the skin, even in regions with substantial topography and coverage of hair. The approach combines thin, ultralow modulus, cellular silicone materials with elastic, strain-limiting fabrics, to yield a compliant but rugged platform for stretchable electronics. Theoretical and experimental studies highlight the mechanics of adhesion and elastic deformation. Demonstrations include cutaneous optical, electrical and radio frequency sensors for measuring hydration state, electrophysiological activity, pulse and cerebral oximetry. Multipoint monitoring of a subject in an advanced driving simulator provides a practical example.

An intelligent health monitoring system using radio-frequency identification technology.

PubMed

Lai, Yeong-Lin; Chen, Chin-Ling; Chang, Ching-Hisang; Hsu, Chih-Yu; Lai, Yeong-Kang; Tseng, Kuo-Kun; Chen, Chih-Cheng; Zheng, Chun-Yi

2015-01-01

Long-term care (LTC) for the elderly has become extremely important in recent years. It is necessary for the different physiological monitoring systems to be integrated on the same interface to help oversee and manage the elderly's needs. This paper presents a novel health monitoring system for LTC services using radio-frequency identification (RFID) technology. Dual-band RFID protocols were included in the system, in which the high-frequency (HF) band of 13.56 MHz was used to identify individuals and the microwave band of 2.45 GHz was used to monitor physiological information. Distinct physiological data, including oxyhemoglobin saturation by pulse oximetry (SpO2), blood pressure, blood sugar, electrocardiogram (ECG) readings, body temperature, and respiration rate, were monitored by various biosensors. The intelligent RFID health monitoring system provided the features of the real-time acquisition of biomedical signals and the identification of personal information pertaining to the elderly and patients in nursing homes.

[Generation of Superoxide Radicals by Complex III in Heart Mitochondria and Antioxidant Effect of Dinitrosyl Iron Complexes at Different Partial Pressure of Oxygen].

PubMed

Dudylina, A L; Ivanova, M V; Shumaev, K B; Ruuge, E K

2016-01-01

The EPR spin-trapping technique and EPR-oximetry were used to study generation of superoxide radicals in heart mitochondria isolated from Wistar rats under conditions of variable oxygen concentration. Lithium phthalocyanine and TEMPONE-15N-D16 were chosen to determine oxygen content in a gas-permeable capillary tube containing mitochondria. TIRON was used as a spin trap. We investigated the influence of different oxygen concentrations in incubation mixture and demonstrated that heart mitochondria can generate superoxide in complex III at different partial pressure of oxygen as well as under the conditions of deep hypoxia (< 5% O2). Dinitrosyl iron complexes with glutathione (the pharmaceutical drug "Oxacom") exerted an antioxidant effect, regardless of the value of the partial pressure of oxygen, but the magnitude and kinetic characteristics of the effect depended on the concentration of the drug.

[Exercise-related risk at anaerobic threshold in patients with chronic obstructive pulmonary disease].

PubMed

Xu, Q F; Yuan, W; Zhao, X J; Li, B; Wang, H Y

2016-02-01

To investigate the exercise-related risk at anaerobic threshold(AT) in patients with chronic obstructive pulmonary disease(COPD). Sixty two patients [men 56, women 6, aged (66±8) yr] with stable COPD in Beijing Friendship Hospital during 2013-2014, participated in this study. Incremental symptom-limited cardiopulmonary exercise test was performed on cycle ergometer. The AT was determined using the V-Slope technique and ventilatory equivalents for carbon dioxide and oxygen. Symptoms, 10-lead electrocardiogram, oxygen saturation by pulse oximetry(SpO(2)) were monitored during exercise. The AT, detectable in 53 patients, occurred at (68±10)% of peak oxygen uptake(peak VO(2)). The SpO(2) was in the safe range (94±2) % and the respiratory reserve was relatively high at AT (i.e. 48%). High-intensity exercise training can be performed in patients with moderate-to- severe COPD without resting oxygen desaturation.

Development of a luminous textile for reflective pulse oximetry measurements

PubMed Central

Krehel, Marek; Wolf, Martin; Boesel, Luciano F.; Rossi, René M.; Bona, Gian-Luca; Scherer, Lukas J.

2014-01-01

In this paper, a textile-based sensing principle for long term photopletysmography (PPG) monitoring is presented. Optical fibers were embroidered into textiles such that out-coupling and in-coupling of light was possible. The “light-in light-out” properties of the textile enabled the spectroscopic characterization of human tissue. For the optimization of the textile sensor, three different carrier fabrics and different fiber modifications were compared. The sample with best light coupling efficiency was successfully used to measure heart rate and SpO2 values of a subject. The latter was determined by using a modified Beer-Lambert law and measuring the light attenuation at two different wavelengths (632 nm and 894 nm). Moreover, the system was adapted to work in reflection mode which makes the sensor more versatile. The measurements were additionally compared with commercially available system and showed good correlation. PMID:25136484

Current diagnosis and treatments for critical congenital heart defects

PubMed Central

ZENG, ZHANDONG; ZHANG, HONGWEI; LIU, FENGLI; ZHANG, NING

2016-01-01

Congenital heart defects (CHD) affect approximately 7% of infants, and account for 3% of all infant deaths. CHD is most often caused by the defects associated with ductus arteriosus, which is a vessel that usually closes shortly after birth. The types of CHD include tetralogy of fallot, hypoplastic left heart syndrome, pulmonary atresia, total anomalous pulmonary venous return, transposition of great arteries, tricuspid atresia and truncus arteriosus. There are some risk factors that can increase the chance of a fetus developing CHD such as prematurity, an existing CHD in a first-degree relative, genetic syndromes, infections in utero, maternal drug consumptions and disorders. CHD is diagnosed is through different techniques including pulse oximetry, echocardiograms and physical exams. In this review, we examined the current incidence of CHD, the risk factors associated with CHD, the current methods of diagnosis and surgical options used to repair the defects. PMID:27168772

Development of a luminous textile for reflective pulse oximetry measurements.

PubMed

Krehel, Marek; Wolf, Martin; Boesel, Luciano F; Rossi, René M; Bona, Gian-Luca; Scherer, Lukas J

2014-08-01

In this paper, a textile-based sensing principle for long term photopletysmography (PPG) monitoring is presented. Optical fibers were embroidered into textiles such that out-coupling and in-coupling of light was possible. The "light-in light-out" properties of the textile enabled the spectroscopic characterization of human tissue. For the optimization of the textile sensor, three different carrier fabrics and different fiber modifications were compared. The sample with best light coupling efficiency was successfully used to measure heart rate and SpO2 values of a subject. The latter was determined by using a modified Beer-Lambert law and measuring the light attenuation at two different wavelengths (632 nm and 894 nm). Moreover, the system was adapted to work in reflection mode which makes the sensor more versatile. The measurements were additionally compared with commercially available system and showed good correlation.

Utilizing a Homecare Platform for Remote Monitoring of Patients with Idiopathic Pulmonary Fibrosis.

PubMed

Panagopoulos, Christos; Malli, Foteini; Menychtas, Andreas; Smyrli, Efstathia-Petrina; Georgountzou, Aikaterini; Daniil, Zoe; Gourgoulianis, Konstantinos I; Tsanakas, Panayiotis; Maglogiannis, Ilias

2017-01-01

Homecare and home telemonitoring are a focal point of emerging healthcare schemes, with proven benefits for both patients, caregivers and providers, including reduction of healthcare costs and improved patients' quality of life, especially in the case of chronic disease management. Studies have evaluated solutions for remote monitoring of chronic patients based on technologies that allow daily symptom and vital signs monitoring, tailored to the needs of specific diseases. In this work, we present an affordable home telemonitoring system for patients with idiopathic pulmonary fibrosis (IPF), based on an application for mobile devices and Bluetooth-enabled sensors for pulse oximetry and blood pressure measurements. Besides monitoring of vital signs, the system incorporates communication via videoconferencing and emergency response, with support from a helpdesk service. A pilot study was conducted, in order to verify the proposed solution's feasibility. The results support the utilization of the system for effective monitoring of patients with IPF.

[On Individualization of Therapeutic Doses of Optical Radiation according to Changes in Parameters of Blood Oxygenation].

PubMed

Zalesskaya, G A

2015-01-01

The effect of in vivo laser irradiation by optical radiation on blood from different patients is studied. The objects of research were three series of blood samples from patients whose treatment course included extracorporeal UV blood irradiation, intravenous laser blood irradiation and supra-venous blood laser irradiation. Before and after irradiation the results on optic oximetry and gas content of venous blood were compared. The results of positive and negative influence of blood irradiation on characteristics of an oxygen exchange in separate patients and on the maintenance of some products of metabolism are represented. It is shown that at the same power dose, their changes depend on individual, initial values of hemoglobin oxygen saturation of venous blood and its photoinduced changes which objectively reflect individual sensitivity of patients to the action of optical radiation on blood and can be used for assessment of the efficiency of phototherapy.

Transformative science education through action research and self-study practices

NASA Astrophysics Data System (ADS)

Calderon, Olga

The research studies human emotions through diverse methods and theoretical lenses. My intention in using this approach is to provide alternative ways of perceiving and interpreting emotions being experienced in the moment of arousal. Emotions are fundamental in human interactions because they are essential in the development of effective relationships of any kind and they can also mediate hostility towards others. I begin by presenting an impressionist auto-ethnography, which narrates a personal account of how science and scientific inquiry has been entrenched in me since childhood. I describe how emotions are an important part of how I perceive and respond to the world around me. I describe science in my life in terms of natural environments, which were the initial source of scientific wonder and bafflement for me. In this auto-ethnography, I recount how social interactions shaped my perceptions about people, the world, and my education trajectory. Furthermore, I illustrate how sociocultural structures are used in different contexts to mediate several life decisions that enable me to pursue a career in science and science education. I also reflect on how some of those sociocultural aspects mediated my emotional wellness. I reveal how my life and science are interconnected and I present my story as a segue to the remainder of the dissertation. In chapters 2 and 3, I address a methodology and associated methods for research on facial expression of emotion. I use a facial action coding system developed by Paul Ekman in the 1970s (Ekman, 2002) to study facial representation of emotions. In chapters 4 and 5, I review the history of oximetry and ways in which an oximeter can be used to obtain information on the physiological expression of emotions. I examine oximetry data in relation to emotional physiology in three different aspects; pulse rate, oxygenation of the blood, and plethysmography (i.e., strength of pulse). In chapters 3 and 5, I include data and observations collected in a science education course for science teachers at Brooklyn College. These observations are only a small part on a larger study of emotions and mindfulness in the science classroom by a group of researchers of the City University of New York. In this context, I explore how, while teaching and learning science, emotions are represented facially and physiologically in terms of oxygenation of the blood and pulse rate and strength.

Rejection of Erroneous Saturation Data in Optical Pulse Oximetry in Newborn Patients

NASA Astrophysics Data System (ADS)

Scalise, L.; Marchionni, Paolo; Carnielli, Virgilio P.

2011-08-01

Pulse oximetry (PO) is extensively used in intensive care unit (ICU); this is mainly due to the fact that it is a non-invasive and real-time monitoring method. PO allows to measure arterial oxygen saturation (SaO2) and in particular hemoglobin oxygenation. Optical PO is typically realized by the use of a clip (to be applied on the ear or on the finger top) containing a couple of monochromatic LED sources and a photodiode. The main drawback with the use of PO is the presence of movement artifacts or disturbance due to optical sources and skin, causing erroneous saturation data. The aim of this work is to present the measurement procedure based on a specially developed algorithm able to reject erroneous oxygen saturation data during long lasting monitoring of patients in ICU and to compare measurement data with reference data provided by EGA. We have collected SaO2 data from a standard PO and used an intensive care unit monitor to collect data. This device was connected to our acquisition system and heart rate (HR) and SaO2 data were acquired and processed by our specially developed algorithm and directly reproduced on the PC screen for use by the clinicians. The algorithm here used for the individuation and rejection of erroneous saturation data is based on the assessment of the difference between the Heart Rate (HR) measured by respectively by the ECG and PO. We have used an emogasanalyzer (EGA) for comparison of the measured data. The study was carried out in a neonatal intensive care unit (NICU), using 817 data coming from 24 patients and the observation time was of about 10000 hours. Results show a reduction in the maximum difference between the SaO2 data measured, simultaneously, on the same patient by the EGA and by the proposed method of 14.20% and of the 4.76% in average over the 817 samples. The measurement method proposed is therefore able to individuate and eliminate the erroneous saturation data due to motion artifacts and reported by the pulse oxymeter. Specifically in neonatal ICU, it allows to come to more efficient individuation of apnea, hypoxia and hyperoxia events and consequently to operate more adequate and efficient therapeutic actions.

Non-contact cardiac pulse rate estimation based on web-camera

NASA Astrophysics Data System (ADS)

Wang, Yingzhi; Han, Tailin

2015-12-01

In this paper, we introduce a new methodology of non-contact cardiac pulse rate estimation based on the imaging Photoplethysmography (iPPG) and blind source separation. This novel's approach can be applied to color video recordings of the human face and is based on automatic face tracking along with blind source separation of the color channels into RGB three-channel component. First of all, we should do some pre-processings of the data which can be got from color video such as normalization and sphering. We can use spectrum analysis to estimate the cardiac pulse rate by Independent Component Analysis (ICA) and JADE algorithm. With Bland-Altman and correlation analysis, we compared the cardiac pulse rate extracted from videos recorded by a basic webcam to a Commercial pulse oximetry sensors and achieved high accuracy and correlation. Root mean square error for the estimated results is 2.06bpm, which indicates that the algorithm can realize the non-contact measurements of cardiac pulse rate.

Celestial and terrestrial tele-ophthalmology: a health monitoring helmet for astronaut/cosmonaut and general public use

NASA Astrophysics Data System (ADS)

Ansari, Rafat R.; Rovati, Luigi; Sebag, Jerry

2001-06-01

A goggles-like head-mounted device equipped with several non-invasive techniques for quantitative medical evaluation of the eye, skin, and brain is envisioned for monitoring the health of astronauts and cosmonauts during long-term space travel and exploration. Real-time non-invasive evaluation of the different structures within these organs will provide indices of the health of these organs, as well as the entire body. The techniques such as dynamic light scattering (for the early detection of cataracts to evaluate effects of cosmic radiation), corneal autofluorescence (to assess extracellular matrix biology (e.g., diabetes), optical polarization (of aqueous fluid to evaluate serum chemistry), laser Doppler velocimetry (of retinal, optic nerve, and choroidal blood flow to assess ocular as well as central nervous system blood flow), reflectometry/oximetry (for oxygen metabolism), optical coherence tomography (for retinal microstructure), and possibility scanning laser technology for intraocular imaging and scanning will be integrated into this compact device.

Controlled exposure of volunteers with chronic obstructive pulmonary disease to sulfur dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linn, W.S.; Fischer, D.A.; Shamoo, D.A.

1985-08-01

Twenty-four volunteers with chronic obstructive pulmonary disease (COPD) were exposed to sulfur dioxide (SO/sub 2/) at 0, 0.4, and 0.8 ppm in an environmental control chamber. Exposures lasted 1 hr and included two 15-min exercise periods (mean exercise ventilation rate 18 liter/min). Pulmonary mechanical function was evaluated before exposures, after initial exercise, and at the end of exposure. Blood oxygenation was measured by ear oximetry before exposure and during the second exercise period. Symptoms were recorded throughout exposure periods and for 1 week afterward. No statistically significant changes in physiology or symptoms could be attributed to SO/sub 2/ exposure. Oldermore » adults with COPD seem less reactive to a given concentration of SO/sub 2/ than heavily exercising young adult asthmatics. This may be due to lower ventilation rates (i.e., lower SO/sub 2/ dose rates) and/or to lower airway reactivity in the COPD group.« less

Cardio-Respiratory Effects of Air Pollution in a Panel Study of Outdoor Physical Activity and Health in Rural Older Adults

PubMed Central

Stieb, David M.; Shutt, Robin; Kauri, Lisa; Mason, Sarah; Chen, Li; Szyszkowicz, Mieczyslaw; Dobbin, Nina A.; Rigden, Marc; Jovic, Branka; Mulholland, Marie; Green, Martin S.; Liu, Ling; Pelletier, Guillaume; Weichenthal, Scott A.; Dales, Robert E.; Luginaah, Isaac

2017-01-01

Objective: To examine cardio-respiratory effects of air pollution in rural older adults exercising outdoors. Methods: Adults 55 and over completed measurements of blood pressure, peak expiratory flow and oximetry daily, and of heart rate variability, endothelial function, spirometry, fraction of exhaled nitric oxide and urinary oxidative stress markers weekly, before and after outdoor exercise, for 10 weeks. Data were analyzed using linear mixed effect models. Results: Pooled estimates combining 2013 (n = 36 participants) and 2014 (n = 41) indicated that an interquartile increase in the air quality health index (AQHI) was associated with a significant (P < 0.05) increase in heart rate (2.1%) and significant decreases in high frequency power (−19.1%), root mean square of successive differences (−9.5%), and reactive hyperemia index (−6.5%). Conclusions: We observed acute subclinical adverse effects of air pollution in rural older adults exercising outdoors. PMID:28628045

Eight-channel time-resolved tissue oximeter for functional muscle studies

NASA Astrophysics Data System (ADS)

Cubeddu, Rinaldo; Biscotti, Giovanni; Pifferi, Antonio; Taroni, Paola; Torricelli, Alessandro; Ferrari, Marco; Quaresima, Valentina

2003-07-01

A portable instrument for tissue oximetry based on time-resolved reflectance spectroscopy was developed. The output pulses of 2 laser diodes (683 and 785 nm, 80 MHz pulse repetition rate, 1 mW average power, 100 ps FWHM) are delayed and coupled into a multimode graded-index fiber (50/125 μm and injected into the tissue. The reflectance photons are collected by 8 independent 1 mm fibers and detected by a 16-anode photomultiplier. A time-correlated single photon counting PC board is used for the parallel acquisition of the curves. Simultaneous estimate of the transport scattering and absorption coefficients is achieved by best fitting of time-resolved reflectance curves with a standard model of Diffusion Theory. The performances of the system were tested on phantoms in terms of stability, reproducibility among channels, and accuracy in the determination of the optical properties. Preliminary in vivo measurements were performed on healthy volunteers to monitor spatial changes in calf (medical and lateral gastrocnemius) oxygen hemoglobin saturation and blood volume during dynamic plantar flexion exercise.

Simulated altitude exposure assessment by hyperspectral imaging

NASA Astrophysics Data System (ADS)

Calin, Mihaela Antonina; Macovei, Adrian; Miclos, Sorin; Parasca, Sorin Viorel; Savastru, Roxana; Hristea, Razvan

2017-05-01

Testing the human body's reaction to hypoxia (including the one generated by high altitude) is important in aeronautic medicine. This paper presents a method of monitoring blood oxygenation during experimental hypoxia using hyperspectral imaging (HSI) and a spectral unmixing model based on a modified Beer-Lambert law. A total of 20 healthy volunteers (males) aged 25 to 60 years were included in this study. A line-scan HSI system was used to acquire images of the faces of the subjects. The method generated oxyhemoglobin and deoxyhemoglobin distribution maps from the foreheads of the subjects at 5 and 10 min of hypoxia and after recovery in a high oxygen breathing mixture. The method also generated oxygen saturation maps that were validated using pulse oximetry. An interesting pattern of desaturation on the forehead was discovered during the study, showing one of the advantages of using HSI for skin oxygenation monitoring in hypoxic conditions. This could bring new insight into the physiological response to high altitude and may become a step forward in air crew testing.

Bayesian estimation of optical properties of the human head via 3D structural MRI

NASA Astrophysics Data System (ADS)

Barnett, Alexander H.; Culver, Joseph P.; Sorensen, A. Gregory; Dale, Anders M.; Boas, David A.

2003-10-01

Knowledge of the baseline optical properties of the tissues of the human head is essential for absolute cerebral oximetry, and for quantitative studies of brain activation. In this work we numerically model the utility of signals from a small 6-optode time-resolved diffuse optical tomographic apparatus for inferring baseline scattering and absorption coefficients of the scalp, skull and brain, when complete geometric information is available from magnetic resonance imaging (MRI). We use an optical model where MRI-segmented tissues are assumed homogeneous. We introduce a noise model capturing both photon shot noise and forward model numerical accuracy, and use Bayesian inference to predict errorbars and correlations on the measurments. We also sample from the full posterior distribution using Markov chain Monte Carlo. We conclude that ~ 106 detected photons are sufficient to measure the brain"s scattering and absorption to a few percent. We present preliminary results using a fast multi-layer slab model, comparing the case when layer thicknesses are known versus unknown.

Update in obstructive sleep apnea syndrome in children.

PubMed

Balbani, Aracy P S; Weber, Silke A T; Montovani, Jair C

2005-01-01

The prevalence of OSAS in children is 0.7-3%, with peak incidence in pre-schoolers. It is characterised by partial or complete upper airway obstruction during sleep, causing intermittent hypoxia. Both anatomical (severe nasal obstruction, craniofacial anomalies, hypertrophy of the pharyngeal lymphoid tissue, laryngeal anomalies, etc.) and functional factors (neuromuscular diseases) predispose to OSAS during childhood. The main cause of OSAS in children in adenotonsillar hypertrophy. The most common clinical manifestations of OSAS are: nocturnal snoring, respiratory pauses, restless sleep and mouth breathing. Nocturnal pulse oximetry, nocturnal noise audio/videotape recording and nap polysomnography are useful tools for screening suspected cases of OSAS in children, and the gold-standard for diagnosis is overnight polysomnography in the sleep laboratory. On the contrary of SAOS adults, children usually present: less arousals associated to apnea events, more numerous apneas/hypopneas during REM sleep, and more significant oxyhemoglobin desaturation even in short apneas. The treatment of OSAS may be surgical (adenotonsillectomy, craniofacial abnormalities correction, tracheostomy) or clinical (sleep hygiene, continuous positive airway pressure--CPAP).

Complementary home mechanical ventilation techniques. SEPAR Year 2014.

PubMed

Chiner, Eusebi; Sancho-Chust, José N; Landete, Pedro; Senent, Cristina; Gómez-Merino, Elia

2014-12-01

This is a review of the different complementary techniques that are useful for optimizing home mechanical ventilation (HMV). Airway clearance is very important in patients with HMV and many patients, particularly those with reduced peak cough flow, require airway clearance (manual or assisted) or assisted cough techniques (manual or mechanical) and suctioning procedures, in addition to ventilation. In the case of invasive HMV, good tracheostomy cannula management is essential for success. HMV patients may have sleep disturbances that must be taken into account. Sleep studies including complete polysomnography or respiratory polygraphy are helpful for identifying patient-ventilator asynchrony. Other techniques, such as bronchoscopy or nutritional support, may be required in patients on HMV, particularly if percutaneous gastrostomy is required. Information on treatment efficacy can be obtained from HMV monitoring, using methods such as pulse oximetry, capnography or the internal programs of the ventilators themselves. Finally, the importance of the patient's subjective perception is reviewed, as this may potentially affect the success of the HMV. Copyright © 2014 SEPAR. Published by Elsevier Espana. All rights reserved.

Cerebral oximetry monitoring in the management of severe hypoxaemia associated with transposition of the great arteries with balloon atrial septostomy.

PubMed

Pérez Moreno, J C; Nájera Losada, D C; Sanabria Carretero, P; Paredes Lacave, Á; Benito Bartolomé, F

2018-05-01

Transposition of the great arteries (D-TGA) is one of the most common congenital heart diseases requiring neonatal surgical intervention. In the desperately ill neonate with TGA and the resultant hypoxaemia, acidemia, and congestive heart failure, improvement is often obtained with balloon atrial septostomy (BAS). Current methods employed to evaluate oxygen delivery and tissue consumption are frequently nonspecific. Near infrared spectroscopy (NIRS) allows a continuous non-invasive measurement of tissue oxygenation which reflects perfusion status in real time. Because little is known about the direct effect of BAS on the neonatal brain and on cerebral oxygenation, we measured the effectiveness of BAS in two patients with D-TGA using NIRS before and after BAS. We concluded BAS improves cerebral oxygen saturation in neonates with D-TGA. Copyright © 2017 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

Experimental model of smoking and simulation of reflux with acid and pepsin in rats.

PubMed

Zen Junior, José Hélio; Del Negro, André; Colli Neto, José Alexandre; Araujo, Marina Rachel; Altemani, Albina Maria; Andreollo, Nelson Adami

2012-01-01

To develop experimental models to evaluate the effects of hydrochloric acid associated with the pepsin instilled in the mucosa of the upper esophagus and the esophagogastric junction of young male rats Wistar, simulating injury caused by gastroesophageal reflux on the mucosa of aero-digestive tract in humans as well as the action of the risk exposure of mucosa to cigarette smoke. Fifty young male Wistar rats divided in 5 groups with 10 animals each one, respectively simulating pharyngo-laryngeal reflux and gastroesophageal reflux, pharyngo-laryngeal reflux and smoking, smoking only, gastroesophageal reflux and control group. The histopathologic studies no recorded neoplasias, only mild changes and no significant alterations. The hemo-oximetry (carboxyhemoglobin and methemoglobim) and CO2 concentration confirm that the animals were submitted to high intensity of exposure to carcinogens in tobacco and its derivatives. The experimental models were highly efficient, practical, easy to use and economical and can be employed in other similar studies to determine the harmful effects by smoking and reflux.

Audit of availability and distribution of paediatric cardiology services and facilities in Nigeria

PubMed Central

Ekure, Ekanem N; Sadoh, Wilson E; Bode-Thomas, Fidelia; Yilgwan, Christopher S; Orogade, Adeola A; Animasahun, Adeola B; Ogunkunle, Oluwatoyin O; Omokhodion, Samuel I; Babaniyi, Iretiola; Anah, Maxwell U; Otaigbe, Barbara E; Olowu, Adebiyi; Okpokowuruk, Frances; Maduka, Ogechi C; Onakpoya, Uvie U; Adiele, Daberechi K; Sani, Usman. M; Asani, Mustapha; Daniels, Queennette; Uzodimma, Chinyere C; Duru, Chika O; Abdulkadir, Mohammad B; Afolabi, Joseph K; Okeniyi, John A

2017-01-01

Summary Background Paediatric cardiac services in Nigeria have been perceived to be inadequate but no formal documentation of availability and distribution of facilities and services has been done. Objective: To evaluate and document the currently available paediatric cardiac services in Nigeria. Methods In this questionnaire-based, cross-sectional descriptive study, an audit was undertaken from January 2010 to December 2014, of the personnel and infrastructure, with their distributions according to geopolitical zones of Nigeria. Results Forty-eight centres participated in the study, with 33 paediatric cardiologists and 31 cardiac surgeons. Echocardiography, electrocardiography and pulse oximetry were available in 45 (93.8%) centres while paediatric intensive care units were in 23 (47.9%). Open-heart surgery was performed in six (12.5%) centres. South-West zone had the majority of centres (20; 41.7%). Conclusions Available paediatric cardiac services in Nigeria are grossly inadequate and poorly distributed. Efforts should be intensified to upgrade existing facilities, establish new and functional centres, and train personnel. PMID:27701490

Audit of availability and distribution of paediatric cardiology services and facilities in Nigeria.

PubMed

Ekure, Ekanem N; Sadoh, Wilson E; Bode-Thomas, Fidelia; Orogade, Adeola A; Animasahun, Adeola B; Ogunkunle, Oluwatoyin O; Babaniyi, Iretiola; Anah, Maxwell U; Otaigbe, Barbara E; Olowu, Adebiyi; Okpokowuruk, Frances; Omokhodion, Samuel I; Maduka, Ogechi C; Onakpoya, Uvie U; Adiele, Daberechi K; Sani, Usman M; Asani, Mustapha; Yilgwan, Christopher S; Daniels, Queennette; Uzodimma, Chinyere C; Duru, Chika O; Abdulkadir, Mohammad B; Afolabi, Joseph K; Okeniyi, John A

Paediatric cardiac services in Nigeria have been perceived to be inadequate but no formal documentation of availability and distribution of facilities and services has been done. To evaluate and document the currently available paediatric cardiac services in Nigeria. In this questionnaire-based, cross-sectional descriptive study, an audit was undertaken from January 2010 to December 2014, of the personnel and infrastructure, with their distributions according to geopolitical zones of Nigeria. Forty-eight centres participated in the study, with 33 paediatric cardiologists and 31 cardiac surgeons. Echocardiography, electrocardiography and pulse oximetry were available in 45 (93.8%) centres while paediatric intensive care units were in 23 (47.9%). Open-heart surgery was performed in six (12.5%) centres. South-West zone had the majority of centres (20; 41.7%). Available paediatric cardiac services in Nigeria are grossly inadequate and poorly distributed. Efforts should be intensified to upgrade existing facilities, establish new and functional centres, and train personnel.

A comparison of oxygen saturation measurements obtained from a 'blue sensor' with a standard sensor.

PubMed

Mawson, Isabel E; Dawson, Jennifer A; Donath, Susan M; Davis, Peter G

2011-10-01

The study aims to investigate pulse oximetry measurements from a 'blue' pulse oximeter sensor against measurements from a 'standard' pulse oximeter sensor in newly born infants. Immediately after birth, both sensors were attached to the infant, one to each foot. SpO₂ measurements were recorded simultaneously from each sensor for 10 min. Agreement between pairs of SpO₂ measurements were calculated using Bland-Altman analysis. Thirty-one infants were studied. There was good correlation between simultaneous SpO₂ measurements from both sensors (r² = 0.75). However, the mean difference between 'blue' and 'standard' sensors was -1.6%, with wide 95% limits of agreement +18.4 to -21.6%. The range of mean difference between sensors from each infant ranged from -20 to +20. The mean difference between the blue and standard sensor SpO₂ measurements is not clinically important. © 2011 The Authors. Journal of Paediatrics and Child Health © 2011 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

Near-infrared spectroscopy and polysomnography during all-night sleep in human subjects

NASA Astrophysics Data System (ADS)

Fantini, Sergio; Aggarwal, Payal; Chen, Kathleen; Franceschini, Maria Angela; Ehrenberg, Bruce L.

2003-10-01

We have performed cerebral near-infrared spectroscopy (NIRS) and polysomnography (electro-encephalography, electro-oculography, electro-myography, pulse oximetry, and respiratory monitoring) during all-night sleep in five human subjects. Polysomnography data were used for sleep staging, while NIRS data were used to measure the concentration and the oxygen saturation of hemoglobin in the frontal brain region. Immediately after sleep onset we observed a decrease in the cerebral concentration of oxy-hemoglobin ([HbO2]) and an increase in the concentration of deoxy-hemoglobin ([Hb]), consistent with a decrease in the cerebral blood flow velocity or an increase in cerebral metabolic rate of oxygen. An opposite trend (increase in [HbO2] and decrease in [Hb]) was usually observed after transition to deep sleep (stages III and IV). During rapid eye movement (REM) sleep, we observed an increase in [HbO2] and decrease in [Hb], consistent with an increase in the cerebral blood flow that overcompensates the increase in the metabolic rate of oxygen associated with REM sleep.

Two-layer optical model of skin for early, non-invasive detection of wound development on the diabetic foot

NASA Astrophysics Data System (ADS)

Yudovsky, Dmitry; Nouvong, Aksone; Schomacker, Kevin; Pilon, Laurent

2010-02-01

Foot ulceration is a debilitating comorbidity of diabetes that may result in loss of mobility and amputation. Optical detection of cutaneous tissue changes due to inflammation and necrosis at the preulcer site could constitute a preventative strategy. A commercial hyperspectral oximetry system was used to measure tissue oxygenation on the feet of diabetic patients. A previously developed predictive index was used to differentiate preulcer tissue from surrounding healthy tissue with a sensitivity of 92% and specificity of 80%. To improve prediction accuracy, an optical skin model was developed treating skin as a two-layer medium and explicitly accounting for (i) melanin content and thickness of the epidermis, (ii) blood content and hemoglobin saturation of the dermis, and (iii) tissue scattering in both layers. Using this forward model, an iterative inverse method was used to determine the skin properties from hyperspectral images of preulcerative areas. The use of this information in lowering the false positive rate was discussed.

Cerebral blood flow and oxygenation in infants after birth asphyxia. Clinically useful information?

PubMed

Greisen, Gorm

2014-10-01

The term 'luxury perfusion' was coined nearly 50 years ago after observation of bright-red blood in the cerebral veins of adults with various brain pathologies. The bright-red blood represents decreased oxygen extraction and hence the perfusion is 'luxurious' compared to oxygen needs. Gradual loss of cellular energy charge during the hours following severe birth asphyxia was observed twenty years later by sequential cranial magnetic resonance spectroscopy. This led to the concept of delayed energy failure that is linked to mitochondrial dysfunction and apoptotic cell death. Abnormally increased perfusion and lack of normal cerebral blood flow regulation are also typically present, but whether the perfusion abnormalities at this secondary stage are detrimental, beneficial, or a mere epiphenomenon remains elusive. In contrast, incomplete reoxygenation of the brain during and following resuscitation is likely to compromise outcome. The clinical value of cerebral oximetry in this context can only be examined in a randomised clinical trial. Copyright © 2014 Elsevier Ltd. All rights reserved.

ANESTHETIC MANAGEMENT OF AN INDO-PACIFIC BOTTLENOSE DOLPHIN (TURSIOPS ADUNCUS) REQUIRING SURGICAL DEBRIDEMENT OF A TAIL ABSCESS.

PubMed

Tamura, Jun; Yanagisawa, Makio; Endo, Yusuke; Ueda, Keiichi; Koga, Haruka; Izumisawa, Yasuharu; Yamashita, Kazuto

2017-03-01

This report describes the anesthetic management of a 14-yr-old, 160-kg, female Indo-Pacific bottlenose dolphin ( Tursiops aduncus ) that underwent surgical debridement for a refractory subcutaneous abscess twice within a 6-mo interval. The animal was otherwise in good physical condition at each anesthetic procedure. Following premedication with intramuscular midazolam and butorphanol, anesthesia was induced with propofol and maintained with sevoflurane by intubation. During surgery ventilation was controlled. Blood pressure was indirectly estimated using either oscillometric or pulse oximetry. Presumed hypotension was managed by adjusting the sevoflurane concentration and infusion of dopamine. During recovery, the dolphin regained adequate spontaneous respiration following intravenous administration of flumazenil and doxapram. The dolphin was extubated at 85 min and 53 min after the first and second surgeries, respectively. Successful weaning from the ventilator and initiation of spontaneous respiration was the most important complication encountered. Establishment of a reliable blood pressure measurement technique is critical to success for anesthesia in this species.

Dynamic Determination of Oxygenation and Lung Compliance in Murine Pneumonectomy

PubMed Central

Gibney, Barry; Lee, Grace S.; Houdek, Jan; Lin, Miao; Miele, Lino; Chamoto, Kenji; Konerding, Moritz A.; Tsuda, Akira; Mentzer, Steven J.

2012-01-01

Thoracic surgical procedures in mice have been applied to a wide range of investigations, but little is known about the murine physiologic response to pulmonary surgery. Using continuous arterial oximetry monitoring and the FlexiVent murine ventilator, we investigated the effect of anesthesia and pneumonectomy on mouse oxygen saturation and lung mechanics. Sedation resulted in a dose-dependent decline of oxygen saturation that ranged from 55–82%. Oxygen saturation was restored by mechanical ventilation with increased rate and tidal volumes. In the mouse strain studied, optimal ventilatory rates were a rate of 200/minute and a tidal volume of 10ml/kg. Sustained inflation pressures, referred to as a "recruitment maneuver," improved lung volumes, lung compliance and arterial oxygenation. In contrast, positive end expiratory pressure (PEEP) had a detrimental effect on oxygenation; an effect that was ameliorated after pneumonectomy. Our results confirm that lung volumes in the mouse are dynamically determined and suggest a threshold level of mechanical ventilation to maintain perioperative oxygen saturation. PMID:21574875

Monitoring pulse oximetry via radiotelemetry in freely-moving lambs.

PubMed

Reix, Philippe; Dumont, Sylvain; Duvareille, Charles; Cyr, Jonathan; Moreau-Bussière, François; Arsenault, Julie; Praud, Jean-Paul

2005-05-12

This study was aimed at validating the use of a custom-made wireless pulse oximeter in freely moving lambs, using radiotelemetry transmission. First, measurements obtained simultaneously using the new, wireless oximeter and a standard commercially-available pulse oximeter (Nonin 8500) were compared in five lambs during 5min episodes of normoxia, hypoxia and hyperoxia. Correlation between the two oximeters for both SpO(2) and heart rate was very good, regardless of oxygenation conditions. Secondly, the capabilities of our device were assessed during more than 45h of polysomnographic recordings in seven lambs. According to the plethysmographic pulse waveform, reliable SpO(2) values were obtained in more than 85% of recording time. Multiple decreases in SpO(2) were readily observed after spontaneous apneas in preterm lambs. It is concluded that our wireless pulse oximeter performs as reliably as a standard pulse oximeter for monitoring SpO(2) variations in lambs, and offers new perspectives for researchers interested in continuous monitoring of oxygenation throughout sleep stages and wakefulness.

Simulated altitude exposure assessment by hyperspectral imaging.

PubMed

Calin, Mihaela Antonina; Macovei, Adrian; Miclos, Sorin; Parasca, Sorin Viorel; Savastru, Roxana; Hristea, Razvan

2017-05-01

Testing the human body’s reaction to hypoxia (including the one generated by high altitude) is important in aeronautic medicine. This paper presents a method of monitoring blood oxygenation during experimental hypoxia using hyperspectral imaging (HSI) and a spectral unmixing model based on a modified Beer–Lambert law. A total of 20 healthy volunteers (males) aged 25 to 60 years were included in this study. A line-scan HSI system was used to acquire images of the faces of the subjects. The method generated oxyhemoglobin and deoxyhemoglobin distribution maps from the foreheads of the subjects at 5 and 10 min of hypoxia and after recovery in a high oxygen breathing mixture. The method also generated oxygen saturation maps that were validated using pulse oximetry. An interesting pattern of desaturation on the forehead was discovered during the study, showing one of the advantages of using HSI for skin oxygenation monitoring in hypoxic conditions. This could bring new insight into the physiological response to high altitude and may become a step forward in air crew testing.

17 O MRS assesses the effect of mild hypothermia on oxygen consumption rate in tumors.

PubMed

Neveu, Marie-Aline; Joudiou, Nicolas; De Preter, Géraldine; Dehoux, Jean-Paul; Jordan, Bénédicte F; Gallez, Bernard

2017-08-01

Although oxygen consumption is a key factor in metabolic phenotyping, its assessment in tumors remains critical, as current technologies generally display poor specificity. The objectives of this study were to explore the feasibility of direct 17 O nuclear magnetic resonance (NMR) spectroscopy to assess oxygen metabolism in tumors and its modulations. To investigate the impact of hypometabolism induction in the murine fibrosarcoma FSAII tumor model, we monitored the oxygen consumption of normothermic (37°C) and hypothermic (32°C) tumor-bearing mice. Hypothermic animals showed an increase in tumor pO 2 (measured by electron paramagnetic resonance oximetry) contrary to normothermic animals. This was related to a decrease in oxygen consumption rate (assessed using 17 O magnetic resonance spectroscopy (MRS) after the inhalation of 17 O 2 -enriched gas). This study highlights the ability of direct 17 O MRS to measure oxygen metabolism in tumors and modulations of tumor oxygen consumption rate. Copyright © 2017 John Wiley & Sons, Ltd.

Responsibility for clinical innovation. A case study in neonatal medicine.

PubMed

Miké, V; Krauss, A N; Ross, G S

1998-03-01

Proper evaluation of clinical innovations and of the process of their diffusion is essential for the development of sound health care policy. This case study examines transcutaneous oxygen monitoring in neonatal intensive care, a procedure that was rapidly adopted in the late 1970s as a scientific breakthrough of great promise, then all but abandoned within a decade in favor of pulse oximetry, a still more recent technology. The study incorporates the results of interviews with representatives of industry as well as biomedical researchers and clinicians involved with these devices. Factors in technology diffusion are analyzed, with special attention to those susceptible to change by policy makers. Participants in the diffusion process also include nurses, hospital administrators, the legal profession, the news media, and the public, but the pivotal role--and hence ultimate responsibility--is seen to be that of the physician. The discussion is presented in the context of a proposed "ethics of evidence" pertinent to medical decision making.

Spectroscopy of Multilayered Biological Tissues for Diabetes Care

NASA Astrophysics Data System (ADS)

Yudovsky, Dmitry

Neurological and vascular complications of diabetes mellitus are known to cause foot ulceration in diabetic patients. Present clinical screening techniques enable the diabetes care provider to triage treatment by identifying diabetic patients at risk of foot ulceration. However, these techniques cannot effectively identify specific areas of the foot at risk of ulceration. This study aims to develop non-invasive optical techniques for accurate assessment of tissue health and viability with spatial resolution on the order of 1 mm². The thesis can be divided into three parts: (1) the use of hyperspectral tissue oximetry to detect microcirculatory changes prior to ulcer formation, (2) development of a two-layer tissue spectroscopy algorithm and its application to detection of callus formation or epidermal degradation prior to ulceration, and (3) multi-layered tissue fluorescence modeling for identification of bacterial growth in existing diabetic foot wounds. The first part of the dissertation describes a clinical study in which hyperspectral tissue oximetry was performed on multiple diabetic subjects at risk of ulceration. Tissue oxyhemoglobin and deoxyhemoglobin concentrations were estimated using the Modified Beer-Lambert law. Then, an ulcer prediction algorithm was developed based on retrospective analysis of oxyhemoglobin and deoxyhemoglobin concentrations in sites that were known to ulcerate. The ulcer prediction algorithm exhibited a large sensitivity but low specificity of 95 and 80%, respectively. The second part of the dissertation revisited the hyperspectral data presented in part one with a new and novel two-layer tissue spectroscopy algorithm. This algorithm was able to detect not only oxyhemoglobin and deoxyhemoglobin concentrations, but also the thickness of the epidermis, and the tissue's scattering coefficient. Specifically, change in epidermal thickness provided insight into the formation of diabetic foot ulcers over time. Indeed, callus formation or the thickening of the epidermis which preempts ulcer formation was detectable prior to ulceration. This added dimension of information increased the specificity of the ulcer prediction algorithm by 7% without reducing the sensitivity. Finally, the third part of the dissertation describes the feasibility of detecting bacteria in open ulcers. First, a semi-empirical model of multi-layered tissue fluorescence was developed. Then, an inverse method was developed and applied to simulated fluorescence emission spectra of diabetic foot wounds infected with Staphylococcus aureus and stained with indocyanine green dye (ICG). The inverse method was able to detect the blood volume fraction, oxygen saturation, and the intrinsic fluorescence spectrum of the ICG dye from simulated fluorescence emission spectra.

Trending and accuracy of noninvasive hemoglobin monitoring in pediatric perioperative patients.

PubMed

Patino, Mario; Schultz, Lindsay; Hossain, Monir; Moeller, Jennifer; Mahmoud, Mohamed; Gunter, Joel; Kurth, C Dean

2014-10-01

Rainbow Pulse CO-Oximetry technology (Masimo Corporation, Irvine, CA) provides continuous and noninvasive measurement of arterial hemoglobin concentration (SpHb). We assessed the trending and accuracy of SpHb by this innovative monitoring compared with Hb concentration obtained with conventional laboratory techniques (Hb) in children undergoing surgical procedures with potential for substantial blood loss. Hb concentrations were recorded from Pulse CO-Oximetry and a conventional hematology analyzer. Regression analysis and 4-quadrant plot were used to evaluate the trending for changes in SpHb and Hb measurements (ΔSpHb and ΔHb). Bias, precision, and limits of agreement of SpHb and of in vivo adjusted SpHb (SpHb - first bias to HB) compared with Hb were calculated. One hundred fifty-eight SpHb-Hb data pairs and 105 delta pairs (ΔSpHb and ΔHb) from 46 patients aged 2 months to 17 years with Hb ranging from 16.7 to 7.9 g/dL were collected. To evaluate trending, the delta pairs (ΔSpHb and ΔHb) were plotted, which revealed a positive correlation (ΔSpHb = 0.022 + 0.76ΔHb) with correlation coefficient r = 0.76, 95% CI [confidence interval] = 0.57-0.86. The bias and precision of SpHb to Hb and in vivo adjusted SpHb were 0.4 ± 1.3 g/dL and 0.1 ± 1.2 g/dL, respectively; the limits of agreement were -2.0 to 3.2 g/dL before in vivo adjustment and -2.4 to 2.2 g/dL after in vivo adjustment (P value = 0.04). The mean percent bias (from the reference Hb concentration) decreased from 4.1% ± 11.9% to 0.7% ± 11.3% (P value = 0.01). No drift in bias over time was observed during the study procedure. Of patient demographic and physiological factors tested for correlation with the SpHb, only perfusion index at sensor site showed a weak correlation. The accuracy of SpHb in children with normal Hb and mild anemia is similar to that previously reported in adults and is independent of patient demographic and physiological states except for a weak correlation with perfusion index. The trending of SpHb and Hb in children with normal Hb and mild anemia showed a positive correlation. Further studies are necessary in children with moderate and severe anemia.

A phase II randomized clinical trial on cerebral near-infrared spectroscopy plus a treatment guideline versus treatment as usual for extremely preterm infants during the first three days of life (SafeBoosC): study protocol for a randomized controlled trial

PubMed Central

2013-01-01

Background Every year in Europe about 25,000 infants are born extremely preterm. These infants have a 20% mortality rate, and 25% of survivors have severe long-term cerebral impairment. Preventative measures are key to reduce mortality and morbidity in an extremely preterm population. The primary objective of the SafeBoosC phase II trial is to examine if it is possible to stabilize the cerebral oxygenation of extremely preterm infants during the first 72 hours of life through the application of cerebral near-infrared spectroscopy (NIRS) oximetry and implementation of an clinical treatment guideline based on intervention thresholds of cerebral regional tissue saturation rStO2. Methods/Design SafeBoosC is a randomized, blinded, multinational, phase II clinical trial. The inclusion criteria are: neonates born more than 12 weeks preterm; decision to conduct full life support; parental informed consent; and possibility to place the cerebral NIRS oximeter within 3 hours after birth. The infants will be randomized into one of two groups. Both groups will have a cerebral oximeter monitoring device placed within three hours of birth. In the experimental group, the cerebral oxygenation reading will supplement the standard treatment using a predefined treatment guideline. In the control group, the cerebral oxygenation reading will not be visible and the infant will be treated according to the local standards. The primary outcome is the multiplication of the duration and magnitude of rStO2 values outside the target ranges of 55% to 85%, that is, the ‘burden of hypoxia and hyperoxia’ expressed in ‘%hours’. To detect a 50% difference between the experimental and control group in %hours, 166 infants in total must be randomized. Secondary outcomes are mortality at term date, cerebral ultrasound score, and interburst intervals on an amplitude-integrated electroencephalogram at 64 hours of life and explorative outcomes include neurodevelopmental outcome at 2 years corrected age, magnetic resonance imaging at term, blood biomarkers at 6 and 64 hours after birth, and adverse events. Discussion Cerebral oximetry guided interventions have the potential to improve neurodevelopmental outcome in extremely preterm infants. It is a logical first step to test if it is possible to reduce the burden of hypoxia and hyperoxia. Trial registration ClinicalTrial.gov, NCT01590316 PMID:23782447

Accuracy of noninvasive and continuous hemoglobin measurement by pulse co-oximetry during preoperative phlebotomy.

PubMed

Dewhirst, Elisabeth; Naguib, Aymen; Winch, Peter; Rice, Julie; Galantowicz, Mark; McConnell, Patrick; Tobias, Joseph D

2014-01-01

In recent years, the continuous noninvasive hemoglobin measurement has been offered by devices using advanced pulse oximetry technology. Accuracy has been established in healthy adults as well as in surgical and intensive care unit patients but not in the setting of acute hemorrhage. In this study, we evaluated the accuracy of such a device in the clinical setting of preoperative phlebotomy thereby mimicking a scenario of acute blood loss. This prospective study included patients undergoing surgical repair of congenital heart disease (CHD) for whom preoperative phlebotomy was planned. Blood was removed after the induction of anesthesia and prior to the start of the surgical procedure. Replacement with crystalloid was guided by hemodynamic variables and cerebral oxygenation measured by near-infrared spectroscopy. Hemoglobin was measured by bedside whole blood analysis (total hemoglobin [tHb]) before and after phlebotomy, and concurrent measurements from the pulse co-oximeter (noninvasive, continuous, or spot-check testing of total hemoglobin [SpHb]) were recorded. The study cohort included 45 patients ranging in age from 3 months to 50 years. Preoperative phlebotomy removed an average of 9.2 mL/kg of blood that was replaced with an average of 7.2 mL/kg of crystalloid. The pre- and postphlebotomy tHb values were 13.0 ± 1.9 and 12.4 ± 1.8 g/dL, respectively. The absolute difference between the tHb and SpHb (▵Hb) was 1.2 ± 0.1 g/dL. Bland-Altman analysis revealed a bias of 0.1 g/dL, a precision of 1.5 g/dL, and 95% limits of agreement of -2.8 to 3.1 g/dL. In 52.2% of the sample sets, the SpHb was within 1 g/dL of the actual hemoglobin value (tHb), and in 80% of the sample sets, the SpHb was within 2 g/dL. No variation in the accuracy of the deviation was noted based on the patient's age, weight, or type of CHD (cyanotic versus acyanotic). The current study demonstrates that the accuracy of continuous, noninvasive hemoglobin measurement was not affected by acute blood loss simulated by preoperative phlebotomy. Although the device provided a clinically acceptable correlation with the actual hemoglobin value and offers the value of a continuous trend monitor, given the precision of the device, it does not appear that actual transfusion decisions can be based on the device alone. © The Author(s) 2013.

Investigating Functional Extension of Optical Coherence Tomography for Spectroscopic Analysis of Blood Oxygen Saturation

NASA Astrophysics Data System (ADS)

Chen, Siyu

Over the past two decades, optical coherence tomography (OCT) has been successfully applied to various fields of biomedical researching and clinical studies, including cardiology, urology, dermatology, dentistry, oncology, and most successfully, ophthalmology. This dissertation seeks to extend the current OCT practice, which is still largely morphology-based, into a new dimension, functional analysis of metabolic activities in vivo. More specifically, the investigation is focused on retrieving blood oxygen saturation (sO2) using intrinsic hemoglobin optical absorption contrast. Most mammalian cells rely on aerobic respiration to support cellular function, which means they consume oxygen to create adenosine triphosphate (ATP). Metabolic rate of oxygen (MRO2), a key hemodynamic parameter, characterizes how much oxygen is consumed during a given period of time, reflecting the metabolic activity of the target tissue. For example, retinal neurons are highly active and almost entirely rely on the moment-to-moment oxygen supply from retinal circulations. Thus, variation in MRO2 reveals the instantaneous activity of these neurons, shedding light on the physiological and pathophysiological change of cellular functions. Eventually, measuring MRO2 can potentially provide a biomarker for early-stage disease diagnosis, and serve as one benchmark for evaluating effectiveness of medical intervention during disease management. Essential in calculating MRO2, blood sO2 measurements using spectroscopic OCT analysis has been attempted as early as 2003. OCT is intrinsically sensitive to the blood optical absorption spectrum due to its wide-band illumination and detection scheme relying on back-scattered photon. However, accurate retrieval of blood sO2 using conventional near infrared (NIR) OCT systems in vivo has remained challenging. It was not until the development of OCT systems using visible light illumination (vis-OCT) when accurate measurement of blood sO2 was reported in live animals in situ. Thus, one question demanding immediate investigation is how the choice of illumination wavelength bands affect the performance of OCT oximetry. This is addressed using two approaches, (1) a numerical study using Monte Carlo methods, and (2) animal experiments involving the development of a vis- and NIR- dual band OCT imaging system. It is indicated that visible light is more suitable for OCT oximetry applications due to the higher absorption contrast between oxyhemoglobin and deoxyhemoglobin. The accuracy of OCT retinal oximetry is established to be around 5 percentage points (pp) regardless of physiological variation of blood sO2, vessel diameter, and is robust over a reasonable selection of sampling geometry. Despite the higher optical scattering experienced in the visible wavelength range, vis-OCT also demonstrated comparable or better imaging capability in terms of resolving anatomical features, imaging resolution, and retrieving other functional indicators such as blood flow. Besides retrieving blood sO2 from vessels directly visualized in structural OCT images, the possibility of using dynamic motion contrast to enhance otherwise non-resolvable micro vessels is investigated. Using this approach, it is subsequently proved that OCT angiography (OCTA) encodes blood absorption contrast and can be used to calculate sO2 within microvasculature. For the first time, measurements of relative sO2 change are reported in choroidal capillaries following inhalation oxygen challenge. This dissertation also represents a translational study that seeks to move technologies developed in the laboratory into real clinical applications. A vis-OCT imaging system with integrated scanning laser ophthalmoscope (SLO) is developed for human subjects. This prototype system can provide three-dimensional (3D) structural images and cross-sections of human fundus similar to that from commercial NIR-OCT systems. In addition, blood sO2 within retinal circulation is successfully retrieved from healthy subjects following spectroscopic analysis. To improve the accuracy of sO2 measurements, a statistical model is formulized. This model describes the noise intensity distribution in Fourier domain (FD) OCT amplitude image, which enables retrieving unbiased true OCT intensity from low signal-to-noise ratio (SNR) images. Finally, a vis-OCT microscope is developed to monitor dynamic changes within the cerebral circulation following ischemic stroke. This study demonstrates the application of vis-OCT beyond ophthalmic imaging, and serves as a proof of concept that vis-OCT has the potential to be employed in a wide-array of biomedical research.

Is air travel safe for those with lung disease?

PubMed

Coker, R K; Shiner, R J; Partridge, M R

2007-12-01

Airlines commonly report respiratory in-flight emergencies; flight outcomes have not been examined prospectively in large numbers of respiratory patients. The current authors conducted a prospective, observational study of flight outcomes in this group. UK respiratory specialists were invited to recruit patients planning air travel. Centres undertook their usual pre-flight assessment. Within 2 weeks of returning, patients completed a questionnaire documenting symptoms, in-flight oxygen use and unscheduled healthcare use. In total, 616 patients were recruited. Of these, 500 (81%) returned questionnaires. The most common diagnoses were airway (54%) and diffuse parenchymal lung disease (23%). In total, 12 patients died, seven before flying and five within 1 month. Pre-flight assessment included oximetry (96%), spirometry (95%), hypoxic challenge (45%) and walk test (10%). Of the patients, 11% did not fly. In those who flew, unscheduled respiratory healthcare use increased from 9% in the 4 weeks prior to travel to 19% in the 4 weeks after travel. However, when compared with self-reported data during the preceding year, medical consultations increased by just 2%. In patients flying after careful respiratory specialist assessment, commercial air travel appears generally safe.

Aerobic photoreactivity of synthetic eumelanins and pheomelanins: generation of singlet oxygen and superoxide anion.

PubMed

Szewczyk, Grzegorz; Zadlo, Andrzej; Sarna, Michal; Ito, Shosuke; Wakamatsu, Kazumasa; Sarna, Tadeusz

2016-11-01

In this work, we examined photoreactivity of synthetic eumelanins, formed by autooxidation of DOPA, or enzymatic oxidation of 5,6-dihydroxyindole-2-carboxylic acid and synthetic pheomelanins obtained by enzymatic oxidation of 5-S-cysteinyldopa or 1:1 mixture of DOPA and cysteine. Electron paramagnetic resonance oximetry and spin trapping were used to measure oxygen consumption and formation of superoxide anion induced by irradiation of melanin with blue light, and time-resolved near-infrared luminescence was employed to determine the photoformation of singlet oxygen between 300 and 600 nm. Both superoxide anion and singlet oxygen were photogenerated by the synthetic melanins albeit with different efficiency. At 450-nm, quantum yield of singlet oxygen was very low (~10 -4 ) but it strongly increased in the UV region. The melanins quenched singlet oxygen efficiently, indicating that photogeneration and quenching of singlet oxygen may play an important role in aerobic photochemistry of melanin pigments and could contribute to their photodegradation and photoaging. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Biomedical engineering at Sandia National Laboratories

NASA Astrophysics Data System (ADS)

Zanner, Mary Ann

1994-12-01

The potential exists to reduce or control some aspects of the U.S. health care expenditure without compromising health care delivery by developing carefully selected technologies which impact favorably on the health care system. A focused effort to develop such technologies is underway at Sandia National Laboratories. As a DOE National Laboratory, Sandia possesses a wealth of engineering and scientific expertise that can be readily applied to this critical national need. Appropriate mechanisms currently exist to allow transfer of technology from the laboratory to the private sector. Sandia's Biomedical Engineering Initiative addresses the development of properly evaluated, cost-effective medical technologies through team collaborations with the medical community. Technology development is subjected to certain criteria including wide applicability, earlier diagnoses, increased efficiency, cost-effectiveness and dual-use. Examples of Sandia's medical technologies include a noninvasive blood glucose sensor, computer aided mammographic screening, noninvasive fetal oximetry and blood gas measurement, burn diagnostics and laser debridement, telerobotics and ultrasonic scanning for prosthetic devices. Sandia National Laboratories has the potential to aid in directing medical technology development efforts which emphasize health care needs, earlier diagnosis, cost containment and improvement of the quality of life.

Truncated hemoglobins in actinorhizal nodules of Datisca glomerata.

PubMed

Pawlowski, K; Jacobsen, K R; Alloisio, N; Ford Denison, R; Klein, M; Tjepkema, J D; Winzer, T; Sirrenberg, A; Guan, C; Berry, A M

2007-11-01

Three types of hemoglobins exist in higher plants, symbiotic, non-symbiotic, and truncated hemoglobins. Symbiotic (class II) hemoglobins play a role in oxygen supply to intracellular nitrogen-fixing symbionts in legume root nodules, and in one case ( Parasponia Sp.), a non-symbiotic (class I) hemoglobin has been recruited for this function. Here we report the induction of a host gene, dgtrHB1, encoding a truncated hemoglobin in Frankia-induced nodules of the actinorhizal plant Datisca glomerata. Induction takes place specifically in cells infected by the microsymbiont, prior to the onset of bacterial nitrogen fixation. A bacterial gene (Frankia trHBO) encoding a truncated hemoglobin with O (2)-binding kinetics suitable for the facilitation of O (2) diffusion ( ) is also expressed in symbiosis. Nodule oximetry confirms the presence of a molecule that binds oxygen reversibly in D. glomerata nodules, but indicates a low overall hemoglobin concentration suggesting a local function. Frankia trHbO is likely to be responsible for this activity. The function of the D. glomerata truncated hemoglobin is unknown; a possible role in nitric oxide detoxification is suggested.

Miniaturized pulse oximeter sensor for continuous vital parameter monitoring

NASA Astrophysics Data System (ADS)

Fiala, Jens; Reichelt, Stephan; Werber, Armin; Bingger, Philipp; Zappe, Hans; Förster, Katharina; Klemm, Rolf; Heilmann, Claudia; Beyersdorf, Friedhelm

2007-07-01

A miniaturized photoplethysmographic sensor system which utilizes the principle of pulse oximetry is presented. The sensor is designed to be implantable and will permit continuous monitoring of important human vital parameters such as arterial blood oxygen saturation as well as pulse rate and shape over a long-term period in vivo. The system employs light emitting diodes and a photo transistor embedded in a transparent elastic cu. which is directly wrapped around an arterial vessel. This paper highlights the specific challenges in design, instrumentation, and electronics associated with that sensor location. In vitro measurements were performed using an artificial circulation system which allows for regulation of the oxygen saturation and pulsatile pumping of whole blood through a section of a domestic pig's arterial vessel. We discuss our experimental results compared to reference CO-oximeter measurements and determine the empirical calibration curve. These results demonstrate the capabilities of the pulse oximeter implant for measurement of a wide range of oxygen saturation levels and pave the way for a continuous and mobile monitoring of high-risk cardiovascular patients.