Sample records for minimum oxygen saturation
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Johnson, Pamela L; Popa, Daniel A; Prisk, G Kim; Edwards, Natalie; Sullivan, Colin E
2010-02-01
Overnight oxyhaemoglobin desaturation is related to AMS. AMS can be debilitating and may require descent. Positive pressure ventilation during sleep at high altitude may prevent AMS and therefore be useful in people travelling to high altitude, who are known to suffer from AMS. Ascent to high altitude results in hypobaric hypoxia and some individuals will develop acute mountain sickness (AMS), which has been shown to be associated with low oxyhaemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake results in a reduction in AMS symptoms and higher oxyhaemoglobin saturation. We aimed to determine whether positive pressure ventilation would prevent AMS by increasing oxygenation during sleep. We compared sleeping oxyhaemoglobin saturation and the incidence and severity of AMS in seven subjects sleeping for two consecutive nights at 3800 m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of AMS were assessed by administration of the Lake Louise questionnaire. We found significant increases in the mean and minimum sleeping oxyhaemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. The use of positive pressure ventilation during sleep at 3800 m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation.
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Steenhaut, Kevin; Lapage, Koen; Bové, Thierry; De Hert, Stefan; Moerman, Annelies
2017-12-01
An increasing number of NIRS devices are used to provide measurements of peripheral tissue oxygen saturation (S t O 2 ). The aim of the present study is to test the hypothesis that despite technological differences between devices, similar trend values will be obtained during a vascular occlusion test. The devices compared are NIRO-200NX, which measures S t O 2 and oxyhemoglobin by spatially resolved spectroscopy and the Beer-Lambert law, respectively, and INVOS 5100C and Foresight Elite, which both measure S t O 2 with the Beer-Lambert law, enhanced with the spatial resolution technique. Forty consenting adults scheduled for CABG surgery were recruited. The respective sensors of the three NIRS devices were applied over the brachioradial muscle. Before induction of anesthesia, 3 min of ischemia were induced by inflating a blood pressure cuff at the upper arm, whereafter cuff pressure was rapidly released. Tissue oxygenation measurements included baseline, minimum and maximum values, desaturation and resaturation slopes, and rise time. Comparisons between devices were performed with the Kruskal-Wallis test with post hoc Mann-Whitney pairwise comparisons. Agreement was evaluated using Bland-Altman plots. Oxyhemoglobin measured with NIRO responded faster than the other NIRS technologies to changes in peripheral tissue oxygenation (20 vs. 27-40 s, p ≤ 0.01). When comparing INVOS with Foresight, oxygenation changes were prompter (upslope 311 [92-523]%/min vs. 114[65-199]%/min, p ≤ 0.01) and more pronounced (minimum value 36 [21-48] vs. 45 [40-51]%, p ≤ 0.01) with INVOS. Significant differences in tissue oxygen saturation measurements were observed, both within the same device as between different devices using the same measurement technology.
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Johnson, PL; Popa, DA; Prisk, GK; Sullivan, CE; Edwards, N
2014-01-01
Background and objectives Ascent to high altitude results in hypobaric hypoxia and some individuals will develop Acute Mountain Sickness, which has been shown to be associated with low oxyhemoglobin saturation during sleep. Previous research has shown that positive end-expiratory pressure by use of expiratory valves in a face mask while awake, results in a reduction in AMS symptoms and higher oxyhemoglobin saturation. We aimed to test whether pressure ventilation during sleep would prevent AMS by keeping oxyhaemoglobin higher during sleep. Methods We compared sleeping oxyhemoglobin saturation and the incidence and severity of Acute Mountain Sickness in seven subjects sleeping for two consecutive nights at 3800m above sea level using either non-invasive positive pressure ventilation that delivered positive inspiratory and expiratory airway pressure via a face mask, or sleeping without assisted ventilation. The presence and severity of Acute Mountain Sickness was assessed by administration of the Lake Louise questionnaire. Results We found significant increases in the mean and minimum sleeping oxyhemoglobin saturation and decreases in AMS symptoms in subjects who used positive pressure ventilation during sleep. Mean and minimum sleeping SaO2 was lower in subjects who developed AMS after the night spent without positive pressure ventilation. Conclusion The use of positive pressure ventilation during sleep at 3800m significantly increased the sleeping oxygen saturation; we suggest that the marked reduction in symptoms of AMS is due to this higher sleeping SaO2. We agree with the findings from previous studies that the development of AMS is associated with a lower sleeping oxygen saturation. PMID:20051046
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14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2011 CFR
2011-01-01
... displaced by water vapor pressure when the breathed air becomes saturated with water vapor at 37 °C). (2) STPD means Standard, Temperature, and Pressure, Dry (which is, 0 °C at 760 mm. Hg with no water vapor...
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14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2013 CFR
2013-01-01
... displaced by water vapor pressure when the breathed air becomes saturated with water vapor at 37 °C). (2) STPD means Standard, Temperature, and Pressure, Dry (which is 0 °C at 760mm Hg with no water vapor...
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14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2014 CFR
2014-01-01
... displaced by water vapor pressure when the breathed air becomes saturated with water vapor at 37 °C). (2) STPD means Standard, Temperature, and Pressure, Dry (which is 0 °C at 760mm Hg with no water vapor...
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Tripp, L D; Chelette, T; Savul, S; Widman, R A
1998-09-01
One of the key factors in maintaining optimal cognitive performance in the high-G environment is the adequate delivery of oxygen to the cerebral tissue. As eye-level blood pressure is compromised at 22 mmHg x G(-1), perfusion to the peripheral cerebral tissues (cerebral cortex) may not be adequate to support the mental demands of flight. This study measured the effect of closed-loop flight simulations (3 min) on cerebral oxygen saturation changes (rSO2), arterial oxygen saturation (SAO2), and heart rate (HR), in both rested (8 h of rest) and sleepless (24 h without sleep) conditions. Subjects (16; 8 males and 8 females) were subjected to G-exposures via closed-loop flight simulations in a series of four 3-min sorties flown by subjects on the Dynamic Environment Simulator (centrifuge) in either a rested or a sleepless state. Prior to the centrifuge flight, subjects were instrumented with sensors for measurement of arterial oxygen saturation (SAO2) and regional cerebral tissue oxygenation (rSO2). Subjects wore the standard flight suit, boots, CSU-13B/P anti-G suit, and the COMBAT EDGE positive-pressure breathing for G-protection system. Significant changes in cerebral and arterial oxygen saturation were observed within groups when comparing pretest baselines and minimum values during the test and pre- and post-G rSO2, SAO2, and HR in both the rested and sleepless state, (p # 0.01), respectively, for each group. Comparisons between groups showed women to have significantly smaller regional cerebral cortex oxygen decreases than men (p # 0.01). No significant changes in SAO2, however, were observed between groups. Both men and women showed a slow recovery of rSO2 values to the prebaseline levels. Sleeplessness had no effect on the rSO2, SAO2, and HR compared with the rested condition. During acceleration, regional cerebral tissue oxygen decreased 13% in men compared with 9% in women. The recovery of cerebral tissue oxygen levels to prebaseline values was retarded somewhat when compared with the recovery response of arterial oxygen saturation.
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Redaelli, Sara; Zanella, Alberto; Milan, Manuela; Isgrò, Stefano; Lucchini, Alberto; Pesenti, Antonio; Patroniti, Nicolò
2016-12-01
Daily nursing in critical care patients may alter vital parameters, especially in the most critically ill patients. The aim of our study was to evaluate feasibility and safety of daily nursing on patients undergoing venous-venous extracorporeal membrane oxygenation (vv-ECMO) for severe respiratory failure. Daily nursing was performed following defined phases (sponge bath, elevation with scooping stretcher, change position of endotracheal tube, dressing replacement). We recorded physiological and ECMO parameters before and during daily nursing in 5 patients for several days (total: 25 daily nursing) and adverse events: desaturation, hypertension, reduction of mixed venous oxygen saturation, arterial oxygen saturation or ECMO blood flow and elevation in minute ventilation. Sedative drug dosage and additional bolus were recorded. Daily nursing was performed in 92 % of cases (23/25), with a minimum of two adverse events per daily nursing. Hypertension and tachycardia were mostly recorded at the beginning, while desaturation, reduction in mixed venous oxygen saturation and blood flow were recorded during elevation with scooping stretcher. Increase in minute ventilation was frequent in spontaneous breathing patients. Additional bolus of sedation was required before and/or during nursing. Daily nursing significantly alters physiologic parameters; thus, it should be performed only when physicians are readily available to treat adverse events.
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Yenigun, A; Karamanli, H
2015-09-01
To investigate the neutrophil-to-lymphocyte ratio and sleep apnoea severity relationship. Patients (n = 178) were assigned to five groups according to apnoea-hypopnea indices and continuous positive airway pressure use. White blood cell, neutrophil, lymphocyte and neutrophil-to-lymphocyte ratio values were compared for each group. The neutrophil-to-lymphocyte ratio values of severe obstructive sleep apnoea syndrome patients (group 4) were significantly higher than those of: control patients (group 1), mild obstructive sleep apnoea syndrome patients (group 2) and patients treated with continuous positive airway pressure (group 5) (p = 0.008, p = 0.008 and p = 0.003). Minimum oxygen saturation values of group 4 were significantly lower than those of groups 1, 2 and 5 (p = 0.0005, p = 0.011 and p = 0.001). There was a positive correlation between apnoea-hypopnea index and neutrophil-to-lymphocyte ratio (r = 0.758, p = 0.034), and a negative correlation between apnoea-hypopnea index and minimum oxygen saturation (r = -0.179, p = 0.012). Neutrophil-to-lymphocyte ratio may be used to determine disease severity, complementing polysomnography.
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Liscum, Fred; Goss, R.L.; Paul, E.M.
1987-01-01
The third approach was a comparison at each site of the mean, maximum, and minimum values computed for seven constituents that did not correlate with discharge. These constituents or properties of water were temperature, pH, dissolved oxygen, dissolved oxygen percent saturation, total-coliform bacteria, fecal-conform bacteria, and fecal-streptococci bacteria. The only consistent water-quality changes observed were with the three bacteria groups, which were decreased by flood-water detention.
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Effects of Cyanate and 2,3-Diphosphoglycerate on Sickling RELATIONSHIP TO OXYGENATION
Jensen, Michael; Bunn, H. Franklin; Halikas, George; Kan, Yuet Wai; Nathan, David G.
1973-01-01
Cyanate and 2,3-diphosphoglycerate (2,3-DPG) both influence the oxygen affinity of hemoglobin. The studies presented here concern the effects of these compounds on the sickling phenomenon. The inhibitory effect of cyanate on sickling is largely due to the fact that it increases the percentage of oxyhemoglobin S at a given oxygen tension. In addition, cyanate inhibits sickling by a mechanism that is independent of oxygenation. In this paper, we have demonstrated that the viscosity of carbamylated sickle blood was lower than that of non-carbamylated controls at the same oxygen saturation. Furthermore, carbamylation resulted in an increase in the minimum concentration of deoxy-sickle hemoglobin required for gelation. Like cyanate, 2,3-DPG affected sickling of intact erythrocytes by two mechanisms. Since 2,3-DPG decreases the percentage of oxyhemoglobin S at a given oxygen tension, sickling is enhanced. In addition, 2,3-DPG had a direct effect. When the intracellular 2,3-DPG concentration was increased in vitro, a greater percentage of cells were sickled at a given oxygen saturation. Conversely, sickling was inhibited in cells in which 2,3-DPG was artificially lowered. These data indicate that the enhancement of sickling by 2,3-DPG is in part independent of its influence on oxygen affinity. PMID:4729047
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14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2012 CFR
2012-01-01
..., minus 47 mm. Hg, which is the tracheal pressure displaced by water vapor pressure when the breathed air becomes saturated with water vapor at 37 °C). (2) STPD means Standard, Temperature, and Pressure, Dry (which is, 0 °C at 760 mm. Hg with no water vapor). [Doc. No. 26344, 58 FR 18978, Apr. 9, 1993] § 23.1443...
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Alderliesten, Thomas; De Vis, Jill B; Lemmers, Petra Ma; Hendrikse, Jeroen; Groenendaal, Floris; van Bel, Frank; Benders, Manon Jnl; Petersen, Esben T
2017-03-01
Although near-infrared spectroscopy is increasingly being used to monitor cerebral oxygenation in neonates, it has a limited penetration depth. The T 2 -prepared Blood Imaging of Oxygen Saturation (T 2 -BIOS) magnetic resonance sequence provides an oxygen saturation estimate on a voxel-by-voxel basis, without needing a respiratory calibration experiment. In 15 neonates, oxygen saturation measured by T 2 -prepared blood imaging of oxygen saturation and near-infrared spectroscopy were compared. In addition, these measures were compared to cerebral blood flow and venous oxygen saturation in the sagittal sinus. A strong linear relation was found between the oxygen saturation measured by magnetic resonance imaging and the oxygen saturation measured by near-infrared spectroscopy ( R 2 = 0.64, p < 0.001). Strong linear correlations were found between near-infrared spectroscopy oxygen saturation, and magnetic resonance imaging measures of frontal cerebral blood flow, whole brain cerebral blood flow and venous oxygen saturation in the sagittal sinus ( R 2 = 0.71, 0.50, 0.65; p < 0.01). The oxygen saturation obtained by T 2 -prepared blood imaging of oxygen saturation correlated with venous oxygen saturation in the sagittal sinus ( R 2 = 0.49, p = 0.023), but no significant correlations could be demonstrated with frontal and whole brain cerebral blood flow. These results suggest that measuring oxygen saturation by T 2 -prepared blood imaging of oxygen saturation is feasible, even in neonates. Strong correlations between the various methods work as a cross validation for near-infrared spectroscopy and T 2 -prepared blood imaging of oxygen saturation, confirming the validity of using of these techniques for determining cerebral oxygenation.
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Association of physical examination with pulmonary artery catheter parameters in acute lung injury.
Grissom, Colin K; Morris, Alan H; Lanken, Paul N; Ancukiewicz, Marek; Orme, James F; Schoenfeld, David A; Thompson, B Taylor
2009-10-01
To correlate physical examination findings, central venous pressure, fluid output, and central venous oxygen saturation with pulmonary artery catheter parameters. Retrospective study. Data from the multicenter Fluid and Catheter Treatment Trial of the National Institutes of Health Acute Respiratory Distress Syndrome Network. Five hundred thirteen patients with acute lung injury randomized to treatment with a pulmonary artery catheter. Correlation of physical examination findings (capillary refill time >2 secs, knee mottling, or cool extremities), central venous pressure, fluid output, and central venous oxygen saturation with parameters from a pulmonary artery catheter. We determined association of baseline physical examination findings and on-study parameters of central venous pressure and central venous oxygen saturation with cardiac index <2.5 L/min/m2 and mixed venous oxygen saturation <60%. We determined correlation of baseline central venous oxygen saturation and mixed venous oxygen saturation and predictive value of a low central venous oxygen saturation for a low mixed venous oxygen saturation. Prevalence of cardiac index <2.5 and mixed venous oxygen saturation <60% was 8.1% and 15.5%, respectively. Baseline presence of all three physical examination findings had low sensitivity (12% and 8%), high specificity (98% and 99%), low positive predictive value (40% and 56%), but high negative predictive value (93% and 86%) for cardiac index <2.5 and mixed venous oxygen saturation <60%, respectively. Central venous oxygen saturation <70% predicted a mixed venous oxygen saturation <60% with a sensitivity 84%,specificity 70%, positive predictive value 31%, and negative predictive value of 96%. Low cardiac index correlated with cool extremities, high central venous pressure, and low 24-hr fluid output; and low mixed venous oxygen saturation correlated with knee mottling and high central venous pressure, but these correlations were not found to be clinically useful. In this subset of patients with acute lung injury, there is a high prior probability that cardiac index and mixed venous oxygen saturation are normal and physical examination findings of ineffective circulation are not useful for predicting low cardiac index or mixed venous oxygen saturation. Central venous oxygen saturation <70% does not accurately predict mixed venous oxygen saturation <60%, but a central venous oxygen saturation >or=70% may be useful to exclude mixed venous oxygen saturation <60%.
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Arousal From Sleep and Sympathetic Excitation During Wakefulness.
Taylor, Keri S; Murai, Hisayoshi; Millar, Philip J; Haruki, Nobuhiko; Kimmerly, Derek S; Morris, Beverley L; Tomlinson, George; Bradley, T Douglas; Floras, John S
2016-12-01
Obstructive apnea during sleep elevates the set point for efferent sympathetic outflow during wakefulness. Such resetting is attributed to hypoxia-induced upregulation of peripheral chemoreceptor and brain stem sympathetic function. Whether recurrent arousal from sleep also influences daytime muscle sympathetic nerve activity is unknown. We therefore tested, in a cohort of 48 primarily nonsleepy, middle-aged, male (30) and female (18) volunteers (age: 59±1 years, mean±SE), the hypothesis that the frequency of arousals from sleep (arousal index) would relate to daytime muscle sympathetic burst incidence, independently of the frequency of apnea or its severity. Polysomnography identified 24 as having either no or mild obstructive sleep apnea (apnea-hypopnea index <15 events/h) and 24 with moderate-to-severe obstructive sleep apnea (apnea-hypopnea index >15 events/h). Burst incidence correlated significantly with arousal index (r=0.53; P<0.001), minimum oxygen saturation (r=-0.43; P=0.002), apnea-hypopnea index (r=0.41; P=0.004), age (r=0.36; P=0.013), and body mass index (r=0.33; P=0.022) but not with oxygen desaturation index (r=0.28; P=0.056). Arousal index was the single strongest predictor of muscle sympathetic nerve activity burst incidence, present in all best subsets regression models. The model with the highest adjusted R 2 (0.456) incorporated arousal index, minimum oxygen saturation, age, body mass index, and oxygen desaturation index but not apnea-hypopnea index. An apnea- and hypoxia-independent effect of sleep fragmentation on sympathetic discharge during wakefulness could contribute to intersubject variability, age-related increases in muscle sympathetic nerve activity, associations between sleep deprivation and insulin resistance or insomnia and future cardiovascular events, and residual adrenergic risk with persistence of hypertension should therapy eliminate obstructive apneas but not arousals. © 2016 American Heart Association, Inc.
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Zhang, Yangfan; Mauduit, Florian; Farrell, Anthony P; Chabot, Denis; Ollivier, Hélène; Rio-Cabello, Adrien; Le Floch, Stéphane; Claireaux, Guy
2017-10-01
We tested the hypothesis that the chronic residual effects of an acute exposure of European sea bass (Dicentrarchus labrax) to chemically dispersed crude oil is manifest in indices of hypoxic performance rather than aerobic performance. Sea bass were pre-screened with a hypoxia challenge test to establish their incipient lethal oxygen saturation (ILOS), but on discovering a wide breadth for individual ILOS values (2.6-11.0% O 2 saturation), fish were subsequently subdivided into either hypoxia sensitive (HS) or hypoxia tolerant (HT) phenotypes, traits that were shown to be experimentally repeatable. The HT phenotype had a lower ILOS and critical oxygen saturation (O 2crit ) compared with the HS phenotype and switched to glycolytic metabolism at a lower dissolved oxygen, even though both phenotypes accumulated lactate and glucose to the same plasma concentrations at ILOS. As initially hypothesized, and regardless of the phenotype considered, we found no residual effect of oil on any of the indices of aerobic performance. Contrary to our hypothesis, however, oil exposure had no residual effect on any of the indices of hypoxic performance in the HS phenotype. In the HT phenotype, on the other hand, oil exposure had residual effects as illustrated by the impaired repeatability of hypoxia tolerance and also by the 24% increase in O 2crit , the 40% increase in scope for oxygen deficit, the 17% increase in factorial scope for oxygen deficit and the 57% increase in accumulated oxygen deficit. Thus, sea bass with a HT phenotype remained chronically impaired for a minimum of 167days following an acute 24-h oil exposure while the HS phenotypes did not. We reasoned that impaired oxygen extraction at gill due to oil exposure activates glycolytic metabolism at a higher dissolved oxygen, conferring on the HT phenotype an inferior hypoxia resistance that might eventually compromise their ability to survive hypoxic episodes. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.
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Development and validation of a cerebral oximeter capable of absolute accuracy.
MacLeod, David B; Ikeda, Keita; Vacchiano, Charles; Lobbestael, Aaron; Wahr, Joyce A; Shaw, Andrew D
2012-12-01
Cerebral oximetry may be a valuable monitor, but few validation data are available, and most report the change from baseline rather than absolute accuracy, which may be affected by individuals whose oximetric values are outside the expected range. The authors sought to develop and validate a cerebral oximeter capable of absolute accuracy. An in vivo research study. A university human physiology laboratory. Healthy human volunteers were enrolled in calibration and validation studies of 2 cerebral oximetric sensors, the Nonin 8000CA and 8004CA. The 8000CA validation study identified 5 individuals with atypical cerebral oxygenation values; their data were used to design the 8004CA sensor, which subsequently underwent calibration and validation. Volunteers were taken through a stepwise hypoxia protocol to a minimum saturation of peripheral oxygen. Arteriovenous saturation (70% jugular bulb venous saturation and 30% arterial saturation) at 6 hypoxic plateaus was used as the reference value for the cerebral oximeter. Absolute accuracy was defined using a combination of the bias and precision of the paired saturations (A(RMS)). In the validation study for the 8000CA sensor (n = 9, 106 plateaus), relative accuracy was an A(RMS) of 2.7, with an absolute accuracy of 8.1, meeting the criteria for a relative (trend) monitor, but not an absolute monitor. In the validation study for the 8004CA sensor (n = 11, 119 plateaus), the A(RMS) of the 8004CA was 4.1, meeting the prespecified success criterion of <5.0. The Nonin cerebral oximeter using the 8004CA sensor can provide absolute data on regional cerebral saturation compared with arteriovenous saturation, even in subjects previously shown to have values outside the normal population distribution curves. Copyright © 2012 Elsevier Inc. All rights reserved.
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Stella, João Paulo Fragomeni; Barletta, Fernando Branco; Giovanella, Larissa Bergesch; Grazziotin-Soares, Renata; Tovo, Maximiano Ferreira; Felippe, Wilson Tadeu; Estrela, Carlos
2015-09-01
The objective of this study was to use pulse oximetry to measure oxygen saturation in permanent maxillary central incisors with normal pulp in 2 different age groups: children/adolescents and adults. Blood oxygen saturation levels were measured using a pulse oximeter in 110 maxillary central incisors of 57 individuals, in 1 of 2 possible age bands, as follows: 28 children/adolescents (7-13 years old) and 29 adults (22-36 years old). The following factors were also analyzed: (1) heart rate (beats/min); (2) oxygen saturation rate measured at the patient's index finger, also using a pulse oximeter; (3) tooth crown dimensions; and (4) the time taken by the oximeter to provide a reading. The mean oxygen saturation level in normal central incisors was higher among children/adolescents (84.35%) than adults (77.88%, P = .003). Oxygen saturation rates measured at the patients' fingers were not correlated with saturation obtained at the teeth (r = 0.10). There was no correlation between oxygen saturation readings and tooth dimensions (buccal surface area), heart rate, or oximeter reading time (P > .05). Oxygen saturation values measured in maxillary central incisors using a pulse oximeter revealed differences between children/adolescents and adults, showing that children/adolescents have higher oxygen saturation levels. There was no correlation between oxygen saturation levels in patients' fingers and values from their teeth or between oxygen saturation readings from central incisors and tooth dimensions (buccal surface), heart rate, or oximeter reading time. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.
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Lichtenstern, C; Koch, C; Röhrig, R; Rosengarten, B; Henrich, M; Weigand, M A
2012-10-01
Early goal-directed hemodynamic optimization has become a cornerstone of sepsis therapy. One major defined goal is to achieve adequate central venous oxygen saturation (SO(2)). This study aimed to investigate the correlation between central venous SO(2) and frontal cerebral near-infrared spectroscopy (NIRS) measurement in patients with severe sepsis and septic shock. The NIRS method provides non-invasive measurement of regional oxygen saturation (rSO(2)) in tissues approximately 2 cm below the optical NIRS sensors which depends on arterial, capillary and venous blood. Thus this system gives site-specific real-time data about the balance of oxygen supply and demand. This was a secondary analysis from a prospective study of surgical intensive care (ICU) patients in the early phase of severe sepsis or septic shock. Bilateral cerebral rSO(2), central venous SO(2), arterial oxygen saturation (S(a)O(2)) and other surrogate parameters of oxygen supply, such as hemoglobin, partial pressure of oxygen and oxygen content in arterial blood were recorded. A total of 16 ICU patients (4 women, median age 65.5 years) were included in the study. As sepsis focus an intra-abdominal infection was detected in 62.5 % of patients, severe pneumonia was determined in 31.3 % and skin and soft tissue infections were recognized in 12.5 %. At study inclusion 50 % of patients had septic shock, the median sequential organ failure assessment (SOFA) score was 10.2 (interquartile range 5.25-8.75) and the median acute physiology and chronic health evaluation II (APACHE II) score was 26 (range 23.25-29.75). Mortality at day 28 was 37.5 %. Minimum rSO(2) (median 58) and right-sided rSO(2) (median 58) values showed a significant correlation in the analysis of receiver operating characteristics (area under the curve 0.844, p= 0.045). A central venous SO(2)< 70 % was indicated by rSO(2)< 56.5 with sensitivity and specificity of 75 % and 100 %, respectively. Cerebral NIRS could provide a fast and easily available side effect-free monitoring that could be used in addition to established procedures for goal-directed treatment in the early phase of sepsis. Further studies should be made in a larger population to verify the correlation found and to investigate the impact of NIRS-directed resuscitation treatment in early sepsis.
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An efficient motion-resistant method for wearable pulse oximeter.
Yan, Yong-Sheng; Zhang, Yuan-Ting
2008-05-01
Reduction of motion artifact and power saving are crucial in designing a wearable pulse oximeter for long-term telemedicine application. In this paper, a novel algorithm, minimum correlation discrete saturation transform (MCDST) has been developed for the estimation of arterial oxygen saturation (SaO2), based on an optical model derived from photon diffusion analysis. The simulation shows that the new algorithm MCDST is more robust under low SNRs than the clinically verified motion-resistant algorithm discrete saturation transform (DST). Further, the experiment with different severity of motions demonstrates that MCDST has a slightly better performance than DST algorithm. Moreover, MCDST is more computationally efficient than DST because the former uses linear algebra instead of the time-consuming adaptive filter used by latter, which indicates that MCDST can reduce the required power consumption and circuit complexity of the implementation. This is vital for wearable devices, where the physical size and long battery life are crucial.
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Which blood oxygen can sensitively indicate shock severity?
NASA Astrophysics Data System (ADS)
Pan, Boan; Li, Kai; Gao, Yuan; Ruan, Zhengshang; Li, Ting
2016-03-01
Clinical shock-monitoring mainly depends on measuring oxygen saturations from SVC blood samples invasively. The golden standard indicator is the central internal jugular vein oxygenation (SjvO2). Using near-infrared spectroscopy (NIRS) also can monitor shock in some papers published, but there is no discussion about which oxygen saturation (cerebral venous oxygen saturation, ScvO2; tissue oxygen saturation of internal jugular area; tissue oxygen saturation of extremities areas) can monitor shock patient more sensitively and accurately. The purpose of this paper is to examine which one is most effective. In order to discuss the problem, we continuously detected 56 critical patients who may be into shock state using NIRS oximeter at prefrontal, internal jugular vein area and forearm, and chose 24 patients who were into shock and then out of shock from the 56 critical patients. Combined with the patients' condition, the pulse oxygen saturation is most sensitively to monitoring shock than the others, and the internal jugular vein area oxygen saturation is most effective.
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Retinal vessel oxygen saturation in a healthy young Chinese population.
Yang, Wei; Fu, Yue; Dong, Yanmin; Lin, Leilei; Huang, Xia; Li, Yujie; Lin, Xiaofeng; Gao, Qianying
2016-06-01
To measure retinal vessel oxygen saturation in a healthy young Chinese population and to determine the effects of multiple factors (gender, age, dioptre, vessel diameter and ocular perfusion pressure - OPP) on retinal oxygen saturation. A total of 126 healthy Chinese individuals aged from 19 to 30 were included in this study. A retinal oximeter (Oxymap T1) was used to measure retinal vessel oxygen saturation by retinal imaging at two different wavelengths. The mean retinal vessel oxygen saturation (Sat_O2 ) of arterioles, venules and arteriovenous (AV) difference overall and in four separate quadrants were measured. Intra-ocular pressure, blood pressure, finger pulse oximetry value, vessel diameter and dioptre were also measured. The correlations between OPP and dioptre, OPP and vessel diameter, and dioptre and vessel diameter were analysed. And the effects of multiple factors on the retinal oxygen saturation were analysed. The mean oxygen saturation was 93.2 ± 6.3% in the retinal arterioles, 60.4 ± 5.3% in venules and 32.9 ± 6.4% in AV difference. The temporal quadrants had lower measurements of arteriolar and venular oxygen saturation and AV difference compared with nasal quadrants (p < 0.001). The oxygen saturation of the arterioles, venules and AV difference were unaffected by any unique factor. Arteriolar and venular retinal oxygen saturation correlated negatively with the product of dioptre and OPP. Arteriolar retinal oxygen saturation correlated positively with the product of dioptre and vessel diameter. This study provided a normal reference of Sat_O2 in healthy young Chinese individuals. It was a reflection of the normal state of retinal oxygen metabolism affected by several factors. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.
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Gochicoa-Rangel, Laura; Pérez-Padilla, José Rogelio; Rodríguez-Moreno, Luis; Montero-Matamoros, Arturo; Ojeda-Luna, Nancy; Martínez-Carbajal, Gema; Hernández-Raygoza, Roberto; Ruiz-Pedraza, Dolores; Fernández-Plata, María Rosario; Torre-Bouscoulet, Luis
2015-01-01
Altitude above sea level and body mass index are well-recognized determinants of oxygen saturation in adult populations; however, the contribution of these factors to oxygen saturation in children is less clear. To explore the contribution of altitude above sea level and body mass index to oxygen saturation in children. A multi-center, cross-sectional study conducted in nine cities in Mexico. Parents signed informed consent forms and completed a health status questionnaire. Height, weight, and pulse oximetry were recorded. We studied 2,200 subjects (52% girls) aged 8.7 ± 3.0 years. Mean body mass index, z-body mass index, and oxygen saturation were 18.1 ± 3.6 kg·m-2, 0.58 ± 1.3, and 95.5 ± 2.4%, respectively. By multiple regression analysis, altitude proved to be the main predictor of oxygen saturation, with non-significant contributions of age, gender, and body mass index. According to quantile regression, the median estimate of oxygen saturation was 98.7 minus 1.7% per km of altitude above sea level, and the oxygen saturation fifth percentile 97.4 minus 2.7% per km of altitude. Altitude was the main determinant of oxygen saturation, which on average decreased 1.7% per km of elevation from a percentage of 98.7 at sea level. In contrast with adults, this study in children found no association between oxygen saturation and obesity or age.
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Campbell, Andrew; Minniti, Caterina P.; Nouraie, Mehdi; Arteta, Manuel; Rana, Sohail; Onyekwere, Onyinye; Sable, Craig; Ensing, Gregory; Dham, Niti; Luchtman-Jones, Lori; Kato, Gregory J.; Gladwin, Mark T.; Castro, Oswaldo L.; Gordeuk, Victor R.
2009-01-01
Summary Low steady state haemoglobin oxygen saturation in patients with sickle cell anaemia has been associated with the degree of anaemia and haemolysis. How much pulmonary dysfunction contributes to low saturation is not clear. In a prospective study of children and adolescents with sickle cell disease aged 3–20 years at steady state and matched controls, 52% of 391 patients versus 24% of 63 controls had steady state oxygen saturation <99% (P < 0·0001), 9% of patients versus no controls had saturation <95% (P = 0·008) and 8% of patients versus no controls had exercise-induced reduction in saturation ≥3%. Decreasing haemoglobin concentration (P ≤ 0·001) and increasing haemolysis (P ≤ 0·003) but not pulmonary function tests were independent predictors of both lower steady-state saturation and exercise-induced reduction in saturation. Neither history of stroke nor history of acute chest syndrome was significantly associated with lower steady-state oxygen saturation or exercise-induced reduction in saturation. Tricuspid regurgitation velocity was higher in patients with lower steady state haemoglobin oxygen saturation (P = 0·003) and with greater decline in oxygen saturation during the six-minute walk (P = 0·022). In conclusion, lower haemoglobin oxygen saturation is independently associated with increasing degrees of anaemia and haemolysis but not pulmonary function abnormalities among children and adolescents with sickle cell disease. PMID:19694721
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Squassoni, Selma Denis; Machado, Nadine Cristina; Lapa, Mônica Silveira; Cordoni, Priscila Kessar; Bortolassi, Luciene Costa; de Oliveira, Juliana Nascimento; Tavares, Cecilia Melo Rosa; Fiss, Elie
2014-01-01
Objective To evaluate the influence of the altitude on the 6-minute walking test in patients with moderate to severe pulmonary disease. Methods Twenty-nine patients performed the 6-minute walk test at a pulmonary rehabilitation clinic in Santo André (above sea level), in São Paulo State, and at the Enseada Beach, in Guarujá (at sea level), also in São Paulo State. Of these 29 patients, 8 did the test both on hard sand and on asphalt to analyze if there were differences in performance during the tests. Data such as heart rate, oxygen saturation, test distance, and Borg scale were compared. Results We found no statistical difference in relation to oxygen saturation at rest before the beginning of the walking test in Santo André 94.67±2.26% and at sea level 95.56±2% (p=0.71). The minimum saturation measured during the test was 87.27±6.54% in Santo André and 89.10±5.41% in Guarujá (p=0.098). There were no differences in the performed distance between the different kinds of terrains; the distance on sand was 387.75±5.02m and on asphalt it was 375.00±6.54m (p=0.654). Regarding oxygen saturation during walking, the pulse oximetry on sand was 95.12±1.80% and on asphalt it was 96.87±1.64% (p=1.05). Conclusion Altitude did not affect the performance of the walking test in patients with moderate to severe pulmonary disease and the results were similar in both cases, on sand and on asphalt. PMID:25628195
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Peters, James G.; Wilber, W.G.; Crawford, Charles G.; Girardi, F.P.
1979-01-01
A digital computer model calibrated to observe stream conditions was used to evaluate water quality in West Fork Blue River, Washington County, IN. Instream dissolved-oxygen concentration averaged 96.5% of saturation at selected sites on West Fork Blue River during two 24-hour summer surveys. This high dissolved-oxygen concentration reflects small carbonaceous and nitrogenous waste loads; adequate dilution of waste by the stream; and natural reaeration. Nonpoint source waste loads accounted for an average of 53.2% of the total carbonaceous biochemical-oxygen demand and 90.2% of the nitrogenous biochemical-oxygen demand. Waste-load assimilation was studiedfor critical summer and winter low flows. Natural streamflow for these conditions was zero, so no benefit from dilution was provided. The projected stream reaeration capacity was not sufficient to maintain the minimum daily dissolved-oxygen concentration (5 milligrams per liter) in the stream with current waste-discharge restrictions. During winter low flow, ammonia toxicity, rather than dissolved-oxygen concentration, was the limiting water-quality criterion downstream from the Salem wastewater-treatment facility. (USGS)
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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.
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Assessment of oxygen saturation in dental pulp of permanent teeth with periodontal disease.
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.
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Schramm, P; Tzanova, I; Hagen, F; Berres, M; Closhen, D; Pestel, G; Engelhard, K
2016-10-01
Neurosurgical operations in the dorsal cranium often require the patient to be positioned in a sitting position. This can be associated with decreased cardiac output and cerebral hypoperfusion, and possibly, inadequate cerebral oxygenation. In the present study, cerebral oxygen saturation was measured during neurosurgery in the sitting position and correlated with cardiac output. Perioperative cerebral oxygen saturation was measured continuously with two different monitors, INVOS ® and FORE-SIGHT ® . Cardiac output was measured at eight predefined time points using transoesophageal echocardiography. Forty patients were enrolled, but only 35 (20 female) were eventually operated on in the sitting position. At the first time point, the regional cerebral oxygen saturation measured with INVOS ® was 70 (sd 9)%; thereafter, it increased by 0.0187% min -1 (P<0.01). The cerebral tissue oxygen saturation measured with FORE-SIGHT ® started at 68 (sd 13)% and increased by 0.0142% min -1 (P<0.01). The mean arterial blood pressure did not change. Cardiac output was between 6.3 (sd 1.3) and 7.2 (1.8) litre min -1 at the predefined time points. Cardiac output, but not mean arterial blood pressure, showed a positive and significant correlation with cerebral oxygen saturation. During neurosurgery in the sitting position, the cerebral oxygen saturation slowly increases and, therefore, this position seems to be safe with regard to cerebral oxygen saturation. Cerebral oxygen saturation is stable because of constant CO and MAP, while the influence of CO on cerebral oxygen saturation seems to be more relevant. NCT01275898. © The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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[Regional cerebral oxygen saturation as a marker of hemodynamic state following cardiac surgery].
García-Hernández, J A; Aldemira-Liz, A; Martínez-López, A I; Cayuela, A; Charlo-Molina, M T; Cano-Franco, J; Loscertales-Abril, M
2013-10-01
Regional cerebral oxygen saturation (rSO₂) is a measure of the general state of perfusion and oxygenation. We aim to analyze the relationship between this and various hemodynamic and respiratory parameters. Forty-three patients, operated on between October 2011 and July 2012, were included in this prospective observational descriptive study. The following parameters were measured: mean arterial pressure, both arterial and central venous oxygen saturation and partial pressures of oxygen and carbon dioxide, and lactate levels. From these parameters, the oxygenation index and the oxygen extraction ratio were calculated. These measurements were studied to evaluate whether rSO₂ correlated significantly with the other parameters. The average age and weight of the patients were 27.3 months and 9.2 kg, respectively. The rSO₂ correlated positively with both central venous oxygen saturation (r=0.73, P<.01) and mean arterial pressure (r=0.59, P<.01), and negatively with the oxygen extraction ratio (r=-0.7, P<.01). No correlation was found with the respiratory parameters. Concordance analysis established an acceptable Kappa index (> 0.4) between the rSO₂ and central venous oxygen saturation, and between the rSO₂ and oxygen extraction ratio. Regional cerebral oxygen saturation correlates well with hemodynamic parameters - mean arterial pressure, venous saturation, and the tissue oxygen extraction. However, it does not correlate with respiratory parameters. Copyright © 2012 Asociación Española de Pediatría. Published by Elsevier Espana. All rights reserved.
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Chen, Pei; Cai, Xiaoxiao; Xu, Lijun; Zhang, Jing; Yang, Ying; Gao, Qianying; Ge, Jian; Yu, Keming; Zhuang, Jing
2017-09-01
To determine whether posterior chamber phakic implantable collamer lens (ICL) surgery in high myopia patients impedes oxygen saturation of retinal vessels. Mean oxygen saturation and diameter in retinal blood vessels were measured before and after ICL implantation surgery to correct high myopia refractive errors (i.e. -6.00 to -20.25 dioptres [D]), using an Oxymap T1 retinal oximeter. In 17 eyes of 17 patients, the Oxymap T1 retinal oximeter detected a small but significant decrease in oxygen saturation of retinal venules, 1-week postoperatively (compared to preoperative measurements). Moreover, at 1 week after ICL implantation, the diameter of patient retinal vessels had consistently contracted, compared to preoperative measurements. By 1 month after ICL surgery, however, both the oxygen saturation and retinal vessel diameter had returned to preoperative levels. Otherwise, no statistically significant difference in oxygen saturation and diameter of retinal arterioles was found when comparing their measurements before and 1 week after implantation. Stable levels of oxygen saturation in retinal vessels, as detected by the Oxymap T1 oximeter, show ICL implantation would not leave lasting impact or adverse effects to retina oxygen saturation in high myopia patients. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.
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Li, Jia; Zhang, Gencheng; Holtby, Helen; Guerguerian, Anne-Marie; Cai, Sally; Humpl, Tilman; Caldarone, Christopher A; Redington, Andrew N; Van Arsdell, Glen S
2008-01-01
Ischemic brain injury is an important morbidity in neonates after the Norwood procedure. Its relationship to systemic hemodynamic oxygen transport is poorly understood. Sixteen neonates undergoing the Norwood procedure were studied. Continuous cerebral oxygen saturation was measured by near-infrared spectroscopy. Continuous oxygen consumption was measured by respiratory mass spectrometry. Pulmonary and systemic blood flow, systemic vascular resistance, oxygen delivery, and oxygen extraction ratio were derived with measurements of arterial, and superior vena cava and pulmonary venous gases and pressures at 2- to 4-hour intervals during the first 72 hours in the intensive care unit. Mean cerebral oxygen saturation was 66% +/- 12% before the operation, reduced to 51% +/- 13% on arrival in the intensive care unit, and remained low during the first 8 hours; it increased to 56% +/- 9% at 72 hours, still significantly lower than the preoperative level (P < .05). Postoperatively, cerebral oxygen saturation was closely and positively correlated with systemic arterial pressure, arterial oxygen saturation, and arterial oxygen tension and negatively with oxygen extraction ratio (P < .0001 for all). Cerebral oxygen saturation was moderately and positively correlated with systemic blood flow and oxygen delivery (P < .0001 for both). It was weakly and positively correlated with pulmonary blood flow (P = .001) and hemoglobin (P = .02) and negatively correlated with systemic vascular resistance (P = .003). It was not correlated with oxygen consumption (P > .05). Cerebral oxygen saturation decreased significantly in neonates during the early postoperative period after the Norwood procedure and was significantly influenced by systemic hemodynamic and metabolic events. As such, hemodynamic interventions to modify systemic oxygen transport may provide further opportunities to reduce the risk of cerebral ischemia and improve neurodevelopmental outcomes.
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Retinal Vessel Oxygen Saturation during 100% Oxygen Breathing in Healthy Individuals
Olafsdottir, Olof Birna; Eliasdottir, Thorunn Scheving; Kristjansdottir, Jona Valgerdur; Hardarson, Sveinn Hakon; Stefánsson, Einar
2015-01-01
Purpose To detect how systemic hyperoxia affects oxygen saturation in retinal arterioles and venules in healthy individuals. Methods Retinal vessel oxygen saturation was measured in 30 healthy individuals with a spectrophotometric retinal oximeter (Oxymap T1). Oximetry was performed during breathing of room air, 100% oxygen (10 minutes, 6L/min) and then again room air (10 minutes recovery). Results Mean oxygen saturation rises modestly in retinal arterioles during 100% oxygen breathing (94.5%±3.8 vs. 92.0%±3.7% at baseline, p<0.0001) and dramatically in retinal venules (76.2%±8.0% vs. 51.3%±5.6%, p<0.0001). The arteriovenous difference decreased during 100% oxygen breathing (18.3%±9.0% vs. 40.7%±5.7%, p<0.0001). The mean diameter of arterioles decreased during 100% oxygen breathing compared to baseline (9.7±1.4 pixels vs. 10.3±1.3 pixels, p<0.0001) and the same applies to the mean venular diameter (11.4±1.2 pixels vs. 13.3±1.5 pixels, p<0.0001). Conclusions Breathing 100% oxygen increases oxygen saturation in retinal arterioles and more so in venules and constricts them compared to baseline levels. The dramatic increase in oxygen saturation in venules reflects oxygen flow from the choroid and the unusual vascular anatomy and oxygen physiology of the eye. PMID:26042732
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Hirche, T O; Born, T; Jungblut, S; Sczepanski, B; Kenn, K; Köhnlein, T; Hirche, H; Wagner, T O
2008-10-27
Oxy-Gen lite, a recently developed combined electrolysis and fuel cell technology, de-novo generates oxygen with high purity for medical use from distilled water and room air. However, its use in patients with chronic respiratory failure has never been evaluated. To test the clinical applicability and safety of Oxy-Gen lite technology, we enrolled 32 COPD patients with chronic hypoxemia and long-term oxygen therapy (LTOT) in a controlled, randomized, multicenter clinical trial. Standard continuous oxygen therapy with a maximal flow rate of 2 L/min was tested against pulsatile oxygen delivery by Oxy-Gen lite. Oxygen saturation at seated-rest was recorded over 30 min and used as a primary read-out parameter. Oxygen saturation was also recorded during mild physical strain (speaking out loud) or overnight's sleep. Both methods of oxygen supply established oxygen saturations within the normal range (i.e., upper plateau of the sigmoid oxyhaemoglobin dissociation curve) compared to breathing room air (p<0.0001). Mean oxygen saturation under standard continuous oxygen flow or Oxy-Gen lite technology during rest, physical strain or sleep proved statistically equivalent (95%CI<2.5% of reference saturation). The use of Oxy-Gen lite in COPD patients with hypoxemia and LTOT
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Bernard, Susan L; An, Dowon; Glenny, Robb W
2004-05-01
This report validates the use and limitations of the Nonin Pulse Oximeter for measuring heart rate and oxygen saturation in rats. Eight anesthetized Sprague-Dawley rats were intubated and catheterized. Oxygen saturation was directly measured from arterial blood by using a Radiometer OSM3 Hemoximeter adjusted for rat blood as well as indirectly by using the Nonin Pulse Oximeter. Oxygen saturation was changed by varying the level of inhaled oxygen. Heart rate was measured in two ways: 1) by using the signal from the Nonin Pulse Oximeter and 2) by counting the pressure pulses from the transduced blood pressure. There was excellent agreement between heart rate values measured by the Nonin Pulse Oximeter and that measured by counting the pulses from the arterial blood pressure recording. The Nonin Pulse Oximeter underestimated oxygen saturations by about 3% to 5% compared to the Hemoximeter. Overall, the pulse oximeter reflected important trends in oxygen saturations, making it a useful tool for laboratory animal medicine.
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Heys, Deborah; Swain, Andrew; Knowles, Sarah; Waugh, Amy; Bailey, Mark
2017-11-29
In developed countries, ambulances normally carry oxygen cylinders but not compressed air. Treatment of acute exacerbations of COPD (AECOPD) with oxygen-driven nebulisers can result in hypercapnia and acidosis. Attempts to avoid this have involved interrupted administration of oxygen. 1 However, small battery-powered air nebulisers are now available. This study aims to compare the prehospital oxygen saturations and treatment of patients suffering from AECOPD before and after the introduction of air nebulisers. The oxygen saturations and treatment of 200 AECOPD patients before and 200 AECOPD patients after the introduction of air nebulisers were compared. Compliance with a target saturation of 88-92% was calculated. The median final oxygen saturation was lower for the post-intervention category (94%) than the pre-intervention category (96%). There was an increase in air nebuliser use from 0% to 56% (p < 0.001) and a decrease in oxygen use from 100% to 71.5% (p < 0.001). There was a numerical increase in the proportion of patients arriving at hospital with oxygen saturations of 88 - 92% following introduction of the air nebulisers (24% vs 16.5%) and a decrease in patients arriving with high saturations (67.5% vs 76.5%). The likelihood of achieving the target oxygen saturations following introduction of air nebulisers increased (odds ratio 1.598; 95% confidence interval 0.974, 2.621). The introduction of prehospital air nebulisers resulted in a reduction in oxygen therapy in patients with AECOPD and a lower median prehospital oxygen saturation. This study supports the use of air nebulisers in the prehospital setting. This article is protected by copyright. All rights reserved.
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Practical remarks on the heart rate and saturation measurement methodology
NASA Astrophysics Data System (ADS)
Kowal, M.; Kubal, S.; Piotrowski, P.; Staniec, K.
2017-05-01
A surface reflection-based method for measuring heart rate and saturation has been introduced as one having a significant advantage over legacy methods in that it lends itself for use in special applications such as those where a person’s mobility is of prime importance (e.g. during a miner’s work) and excluding the use of traditional clips. Then, a complete ATmega1281-based microcontroller platform has been described for performing computational tasks of signal processing and wireless transmission. In the next section remarks have been provided regarding the basic signal processing rules beginning with raw voltage samples of converted optical signals, their acquisition, storage and smoothing. This chapter ends with practical remarks demonstrating an exponential dependence between the minimum measurable heart rate and the readout resolution at different sampling frequencies for different cases of averaging depth (in bits). The following section is devoted strictly to the heart rate and hemoglobin oxygenation (saturation) measurement with the use of the presented platform, referenced to measurements obtained with a stationary certified pulsoxymeter.
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High or low oxygen saturation and severe retinopathy of prematurity: a meta-analysis.
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.
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Schmidt, Barbara; Roberts, Robin S; Whyte, Robin K; Asztalos, Elizabeth V; Poets, Christian; Rabi, Yacov; Solimano, Alfonso; Nelson, Harvey
2014-10-01
To compare oxygen saturations as displayed to caregivers on offset pulse oximeters in the 2 groups of the Canadian Oxygen Trial. In 5 double-blind randomized trials of oxygen saturation targeting, displayed saturations between 88% and 92% were offset by 3% above or below the true values but returned to true values below 84% and above 96%. During the transition, displayed values remained static at 96% in the lower and at 84% in the higher target group during a 3% change in true saturations. In contrast, displayed values changed rapidly from 88% to 84% in the lower and from 92% to 96% in the higher target group during a 1% change in true saturations. We plotted the distributions of median displayed saturations on days with >12 hours of supplemental oxygen in 1075 Canadian Oxygen Trial participants to reconstruct what caregivers observed at the bedside. The oximeter masking algorithm was associated with an increase in both stability and instability of displayed saturations that occurred during the transition between offset and true displayed values at opposite ends of the 2 target ranges. Caregivers maintained saturations at lower displayed values in the higher than in the lower target group. This differential management reduced the separation between the median true saturations in the 2 groups by approximately 3.5%. The design of the oximeter masking algorithm may have contributed to the smaller-than-expected separation between true saturations in the 2 study groups of recent saturation targeting trials in extremely preterm infants. Copyright © 2014 Elsevier Inc. All rights reserved.
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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.
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Whyte, Robin K; Nelson, Harvey; Roberts, Robin S; Schmidt, Barbara
2017-03-01
It has been reported in the 3 Benefits of Oxygen Saturation Targeting (BOOST-II) trials that changes in oximeter calibration software resulted in clearer separation between the oxygen saturations in the two trial target groups. A revised analysis of the published BOOST-II data does not support this conclusion. Copyright © 2016 Elsevier Inc. All rights reserved.
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Teschler, Sebastian; Jarosch, Inga; Christle, Jeffrey W; Hitzl, Wolfgang; Kenn, Klaus
2016-01-01
The two-minute walk test (2MWT) is less well validated than the well-known six-minute walk test (6MWT) as a field walking test in patients with chronic obstructive pulmonary disease (COPD). The primary objective of this study was to compare the accuracy of the 2MWT to the 6MWT in detecting exercise-induced oxygen desaturation in patients with severe COPD. Twenty-six patients with COPD (age: 61 ± 10 years, forced expired volume in one second: 37 ± 10%) that were normoxemic at rest performed a 2MWT and a 6MWT under normal ambient conditions on two consecutive days in random order. Oxygen saturation, total walking distance, heart rate, breathing frequency, dyspnea, and leg fatigue were evaluated. Average walking distances were 150 m (95% confidence interval (95% CI): 134–165 m) and 397 m (95% CI: 347–447 m) for the 2MWT and 6MWT, respectively (r = 0.80, p < 0.0001). The difference in minimum oxygen saturation during the 2MWT (83%, 95% CI: 81–86%) and 6MWT (mean 82%, 95% CI: 80–84%) was not statistically different and the data strongly correlated between the groups (r = 0.81, p < 0.0001). Other measurements from the 6MWT, including heart rate, breathing rate, and levels of perceived exertion were also comparable in 2MWT. The 2MWT showed comparable validity in detecting exercise-induced oxygen desaturation in patients with severe COPD compared to the 6MWT. PMID:26961775
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Gloeckl, Rainer; Teschler, Sebastian; Jarosch, Inga; Christle, Jeffrey W; Hitzl, Wolfgang; Kenn, Klaus
2016-03-08
The two-minute walk test (2MWT) is less well validated than the well-known six-minute walk test (6MWT) as a field walking test in patients with chronic obstructive pulmonary disease (COPD). The primary objective of this study was to compare the accuracy of the 2MWT to the 6MWT in detecting exercise-induced oxygen desaturation in patients with severe COPD. Twenty-six patients with COPD (age: 61 ± 10 years, forced expired volume in one second: 37 ± 10%) that were normoxemic at rest performed a 2MWT and a 6MWT under normal ambient conditions on two consecutive days in random order. Oxygen saturation, total walking distance, heart rate, breathing frequency, dyspnea, and leg fatigue were evaluated. Average walking distances were 150 m (95% confidence interval (95% CI): 134-165 m) and 397 m (95% CI: 347-447 m) for the 2MWT and 6MWT, respectively (r = 0.80, p < 0.0001). The difference in minimum oxygen saturation during the 2MWT (83%, 95% CI: 81-86%) and 6MWT (mean 82%, 95% CI: 80-84%) was not statistically different and the data strongly correlated between the groups (r = 0.81, p < 0.0001). Other measurements from the 6MWT, including heart rate, breathing rate, and levels of perceived exertion were also comparable in 2MWT. The 2MWT showed comparable validity in detecting exercise-induced oxygen desaturation in patients with severe COPD compared to the 6MWT. © The Author(s) 2016.
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Oxygen saturation in the dental pulp of permanent teeth: a critical review.
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.
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Suwattanaphim, Suparach; Yodavuhd, Sirisanpang; Puangsa-art, Supalarp
2015-07-01
Oxygen Saturation is one of the important data to determine patient status and worldwide applied in several situations. Evaluation about status of immediate perinatal period of the infant usually uses clinical assessment, Apgar scoring, which had been used for a long time without other scientific measurement. Pulse oximeter the non-invasive measurement of oxygen saturation, may play role for oxygen saturation evaluation in newborn that immediately change from intra to extra uterine environment. Monitoring the time duration that immediately born infants by normal labor or Cesarean section modes, used to archived target oxygen saturation (SpO) and looking for the other factors that influence oxygen saturation adaptation. The data of the 553 infants born in Charoenkrung Pracharak Hospital, Bangkok, Thailand between October 2012 and April 2013 were collected. The 204 healthy newborns that met all criteria were studied. All infants were recorded pulse oximeter from the second to the tenth minute after birth. They were grouped by several factors such as maternal gravidity, gestational age, mode of delivery, Apgar score, birth weight, and sex. Time interval to achieve target oxygen saturation (SpO2 ≥ 90%) was collected for analysis. The oxygen saturation of infants immediately after birth showed an increase. Median time interval was 6.5 (2-10) minutes for 90% saturation and 7 (2-10) minutes for 95% saturation, respectively. Only mode of delivery showed statistical significant time difference (p < 0.001). A Cox proportional hazards analysis of the Kaplan-Meier curves demonstrated that infants born by cesarean delivery took significantly longer time to reach a stable SpO2 ≥ 90% than infants born by vaginal delivery (95% CI = 1.28 to 2.74; p < 0.01). A newly born infant has to take 6.5 minutes (2-10) after birth to adjust their oxygen saturation to reach normal higher level of extra uterine life, median SpO2 of 90%. Furthermore, mode of delivery makes a significant difference of oxygen saturation status; the cesarean route takes significantly longer time than the vaginal route to achieve SpO2 ≥ 90%.
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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).
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Development of an oxygen saturation measuring system by using near-infrared spectroscopy
NASA Astrophysics Data System (ADS)
Kono, K.; Nakamachi, E.; Morita, Y.
2017-08-01
Recently, the hypoxia imaging has been recognized as the advanced technique to detect cancers because of a strong relationship with the biological characterization of cancer. In previous studies, hypoxia imaging systems for endoscopic diagnosis have been developed. However, these imaging technologies using the visible light can observe only blood vessels in gastric mucous membrane. Therefore, they could not detect scirrhous gastric cancer which accounts for 10% of all gastric cancers and spreads rapidly into submucous membrane. To overcome this problem, we developed a measuring system of blood oxygen saturation in submucous membrane by using near-infrared (NIR) spectroscopy. NIR, which has high permeability for bio-tissues and high absorbency for hemoglobin, can image and observe blood vessels in submucous membrane. NIR system with LED lights and a CCD camera module was developed to image blood vessels. We measured blood oxygen saturation using the optical density ratio (ODR) of two wavelengths, based on Lambert-Beer law. To image blood vessel clearly and measure blood oxygen saturation accurately, we searched two optimum wavelengths by using a multilayer human gastric-like phantom which has same optical properties as human gastric one. By using Monte Carlo simulation of light propagation, we derived the relationship between the ODR and blood oxygen saturation and elucidated the influence of blood vessel depth on measuring blood oxygen saturation. The oxygen saturation measuring methodology was validated with experiments using our NIR system. Finally, it was confirmed that our system can detect oxygen saturation in various depth blood vessels accurately.
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Oxygen saturation in optic nerve head structures by hyperspectral image analysis.
Beach, James; Ning, Jinfeng; Khoobehi, Bahram
2007-02-01
A method is presented for the calculation and visualization of percent blood oxygen saturation from specific tissue structures in hyperspectral images of the optic nerve head (ONH). Trans-pupillary images of the primate optic nerve head and overlying retinal blood vessels were obtained with a hyperspectral imaging (HSI) system attached to a fundus camera. Images were recorded during normal blood flow and after partially interrupting flow to the ONH and retinal circulation by elevation of the intraocular pressure (IOP) from 10 mmHg to 55 mmHg in steps. Percent oxygen saturation was calculated from groups of pixels associated with separate tissue structures, using a linear least-squares curve fit of the recorded hemoglobin spectrum to reference spectra obtained from fully oxygenated and deoxygenated red cell suspensions. Color maps of saturation were obtained from a new algorithm that enables comparison of oxygen saturation from large vessels and tissue areas in hyperspectral images. Percent saturation in retinal vessels and from the average over ONH structures (IOP = 10 mmHg) was (mean +/- SE): artery 81.8 +/- 0.4%, vein 42.6 +/- 0.9%, average ONH 68.3 +/- 0.4%. Raising IOP from 10 mmHg to 55 mmHg for 5 min caused blood oxygen saturation to decrease (mean +/- SE): artery 46.1 +/- 6.2%, vein 36.1 +/- 1.6%, average ONH 41.9 +/- 1.6%. The temporal cup showed the highest saturation at low and high IOP (77.3 +/- 1.0% and 60.1 +/- 4.0%) and the least reduction in saturation at high IOP (22.3%) compared with that of the average ONH (38.6%). A linear relationship was found between saturation indices obtained from the algorithm and percent saturation values obtained by spectral curve fits to calibrated red cell samples. Percent oxygen saturation was determined from hyperspectral images of the ONH tissue and retinal vessels overlying the ONH at normal and elevated IOP. Pressure elevation was shown to reduce blood oxygen saturation in vessels and ONH structures, with the smallest reduction in the ONH observed in the temporal cup. IOP-induced saturation changes were visualized in color maps using an algorithm that follows saturation-dependent changes in the blood spectrum and blood volume differences across tissue. Reduced arterial saturation at high IOP may have resulted from a flow-dependent mechanism.
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Effects of Surface Oxygen on the Performance of Carbon as an Anode in Lithium-Ion Batteries
NASA Technical Reports Server (NTRS)
Hung, Ching-Cheh; Clark, Gregory W.
2001-01-01
Carbon materials with similar bulk structure but different surface oxygen were compared for their performance as anodes in lithium-ion battery. The bulk structure was such that the graphene planes were perpendicular to the surface. Three types of surfaces were examined: surface containing C=O type oxygen. surface containing -O-C type oxygen, and surface containing high concentration of active sites. The test involved cycles of lithium insertion into and release from the carbon materials, which was in the half cells of carbon/saturated LiI-50/50 (vol %) EC and DMC/lithium. During the first cycle of lithium insertion, the presence of adsorbed oxygen, -O-C type oxygen, active carbon sites, and C=O type oxygen resulted in the formation of solid-electrolyte interface (SEI) when the carbon's voltage relative to lithium metal was >1.35, 1 to 1.35, 0.5 to 1, and 0.67 to 0.7 V, respectively. An optimum -O-C type oxygen and a minimum C=O type oxygen was found to increase the reversible and decrease the irreversible capacity of carbon. Active sites on the carbon surface result in a large irreversible capacity and a second lithium insertion-release mechanism. However, this new mechanism has a short cycle life.
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Retinal oxygen saturation before and after glaucoma surgery.
Nitta, Eri; Hirooka, Kazuyuki; Shimazaki, Takeru; Sato, Shino; Ukegawa, Kaori; Nakano, Yuki; Tsujikawa, Akitaka
2017-08-01
This study compared retinal vessel oxygen saturation before and after glaucoma surgery. Retinal oxygen saturation in glaucoma patients was measured using a non-invasive spectrophotometric retinal oximeter. Adequate image quality was found in 49 of the 108 consecutive glaucoma patients recruited, with 30 undergoing trabeculectomy, 11 EX-PRESS and eight trabeculotomy. Retinal oxygen saturation measurements in the retinal arterioles and venules were performed at 1 day prior to and at approximately 10 days after surgery. Statistical analysis was performed using a Student's t-test. After glaucoma surgery, intraocular pressure (IOP) decreased from 19.8 ± 7.7 mmHg to 9.0 ± 5.7 mmHg (p < 0.001). Although oxygen saturation in retinal arterioles remained unchanged before and after surgery (104.7 ± 10.6% before and 105.4 ± 9.3% after surgery, p = 0.58), the oxygen saturation in the venules increased from 54.9 ± 7.4% to 57.4 ± 5.7% (p = 0.01). Intraocular pressure (IOP) decreases caused by glaucoma surgery had an effect on the retinal venous oxygen saturation. © 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.
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Roffe, Christine; Nevatte, Tracy; Sim, Julius; Bishop, Jon; Ives, Natalie; Ferdinand, Phillip; Gray, Richard
2017-09-26
Hypoxia is common in the first few days after acute stroke, is frequently intermittent, and is often undetected. Oxygen supplementation could prevent hypoxia and secondary neurological deterioration and thus has the potential to improve recovery. To assess whether routine prophylactic low-dose oxygen therapy was more effective than control oxygen administration in reducing death and disability at 90 days, and if so, whether oxygen given at night only, when hypoxia is most frequent, and oxygen administration is least likely to interfere with rehabilitation, was more effective than continuous supplementation. In this single-blind randomized clinical trial, 8003 adults with acute stroke were enrolled from 136 participating centers in the United Kingdom within 24 hours of hospital admission if they had no clear indications for or contraindications to oxygen treatment (first patient enrolled April 24, 2008; last follow-up January 27, 2015). Participants were randomized 1:1:1 to continuous oxygen for 72 hours (n = 2668), nocturnal oxygen (21:00 to 07:00 hours) for 3 nights (n = 2667), or control (oxygen only if clinically indicated; n = 2668). Oxygen was given via nasal tubes at 3 L/min if baseline oxygen saturation was 93% or less and at 2 L/min if oxygen saturation was greater than 93%. The primary outcome was reported using the modified Rankin Scale score (disability range, 0 [no symptoms] to 6 [death]; minimum clinically important difference, 1 point), assessed at 90 days by postal questionnaire (participant aware, assessor blinded). The modified Rankin Scale score was analyzed by ordinal logistic regression, which yields a common odds ratio (OR) for a change from one disability level to the next better (lower) level; OR greater than 1.00 indicates improvement. A total of 8003 patients (4398 (55%) men; mean [SD] age, 72 [13] years; median National Institutes of Health Stroke Scale score, 5; mean baseline oxygen saturation, 96.6%) were enrolled. The primary outcome was available for 7677 (96%) participants. The unadjusted OR for a better outcome (calculated via ordinal logistic regression) was 0.97 (95% CI, 0.89 to 1.05; P = .47) for oxygen vs control, and the OR was 1.03 (95% CI, 0.93 to 1.13; P = .61) for continuous vs nocturnal oxygen. No subgroup could be identified that benefited from oxygen. At least 1 serious adverse event occurred in 348 (13.0%) participants in the continuous oxygen group, 294 (11.0%) in the nocturnal group, and 322 (12.1%) in the control group. No significant harms were identified. Among nonhypoxic patients with acute stroke, the prophylactic use of low-dose oxygen supplementation did not reduce death or disability at 3 months. These findings do not support low-dose oxygen in this setting. ISRCTN Identifier: ISRCTN52416964.
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Development and testing of an artificial arterial and venous pulse oximeter.
Cloete, G; Fourie, P R; Scheffer, C
2013-01-01
The monitoring of patients healthcare is of a prime importance to ensure their efficient and effective treatment. Monitoring blood oxygen saturation is a field which has grown significantly in recent times and more specifically in tissues affected by diseases or conditions that may negatively affect the function of the tissue. This study involved the development and testing of a highly sensitive non-invasive blood oxygen saturation monitoring device. A device that can be used to continuously monitor the condition of tissue affected by diseases which affect the blood flow through the tissue, and the oxygen usage in tissue. The device's system was designed to specifically monitor occluded tissue which has low oxygen saturations and low perfusion. Although with limitted validation the system was unable to accurately measure the venous oxygenation specifically, but it was able to measure the mixed oxygen saturation. With further research it would be possible to validate the system for measuring both the arterial and venous oxygen saturations.
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Nevatte, Tracy; Sim, Julius; Bishop, Jon; Ives, Natalie; Ferdinand, Phillip; Gray, Richard
2017-01-01
Importance Hypoxia is common in the first few days after acute stroke, is frequently intermittent, and is often undetected. Oxygen supplementation could prevent hypoxia and secondary neurological deterioration and thus has the potential to improve recovery. Objective To assess whether routine prophylactic low-dose oxygen therapy was more effective than control oxygen administration in reducing death and disability at 90 days, and if so, whether oxygen given at night only, when hypoxia is most frequent, and oxygen administration is least likely to interfere with rehabilitation, was more effective than continuous supplementation. Design, Setting, and Participants In this single-blind randomized clinical trial, 8003 adults with acute stroke were enrolled from 136 participating centers in the United Kingdom within 24 hours of hospital admission if they had no clear indications for or contraindications to oxygen treatment (first patient enrolled April 24, 2008; last follow-up January 27, 2015). Interventions Participants were randomized 1:1:1 to continuous oxygen for 72 hours (n = 2668), nocturnal oxygen (21:00 to 07:00 hours) for 3 nights (n = 2667), or control (oxygen only if clinically indicated; n = 2668). Oxygen was given via nasal tubes at 3 L/min if baseline oxygen saturation was 93% or less and at 2 L/min if oxygen saturation was greater than 93%. Main Outcomes and Measures The primary outcome was reported using the modified Rankin Scale score (disability range, 0 [no symptoms] to 6 [death]; minimum clinically important difference, 1 point), assessed at 90 days by postal questionnaire (participant aware, assessor blinded). The modified Rankin Scale score was analyzed by ordinal logistic regression, which yields a common odds ratio (OR) for a change from one disability level to the next better (lower) level; OR greater than 1.00 indicates improvement. Results A total of 8003 patients (4398 (55%) men; mean [SD] age, 72 [13] years; median National Institutes of Health Stroke Scale score, 5; mean baseline oxygen saturation, 96.6%) were enrolled. The primary outcome was available for 7677 (96%) participants. The unadjusted OR for a better outcome (calculated via ordinal logistic regression) was 0.97 (95% CI, 0.89 to 1.05; P = .47) for oxygen vs control, and the OR was 1.03 (95% CI, 0.93 to 1.13; P = .61) for continuous vs nocturnal oxygen. No subgroup could be identified that benefited from oxygen. At least 1 serious adverse event occurred in 348 (13.0%) participants in the continuous oxygen group, 294 (11.0%) in the nocturnal group, and 322 (12.1%) in the control group. No significant harms were identified. Conclusions and Relevance Among nonhypoxic patients with acute stroke, the prophylactic use of low-dose oxygen supplementation did not reduce death or disability at 3 months. These findings do not support low-dose oxygen in this setting. Trial Registration ISRCTN Identifier: ISRCTN52416964 PMID:28973619
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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.
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Measuring hemoglobin amount and oxygen saturation of skin with advancing age
NASA Astrophysics Data System (ADS)
Watanabe, Shumpei; Yamamoto, Satoshi; Yamauchi, Midori; Tsumura, Norimichi; Ogawa-Ochiai, Keiko; Akiba, Tetsuo
2012-03-01
We measured the oxygen saturation of skin at various ages using our previously proposed method that can rapidly simulate skin spectral reflectance with high accuracy. Oxygen saturation is commonly measured by a pulse oximeter to evaluate oxygen delivery for monitoring the functions of heart and lungs at a specific time. On the other hand, oxygen saturation of skin is expected to assess peripheral conditions. Our previously proposed method, the optical path-length matrix method (OPLM), is based on a Monte Carlo for multi-layered media (MCML), but can simulate skin spectral reflectance 27,000 times faster than MCML. In this study, we implemented an iterative simulation of OPLM with a nonlinear optimization technique such that this method can also be used for estimating hemoglobin concentration and oxygen saturation from the measured skin spectral reflectance. In the experiments, the skin reflectance spectra of 72 outpatients aged between 20 and 86 years were measured by a spectrophotometer. Three points were measured for each subject: the forearm, the thenar eminence, and the intermediate phalanx. The result showed that the oxygen saturation of skin remained constant at each point as the age varied.
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NASA Astrophysics Data System (ADS)
Tiano, Laura; Garcia-Robledo, Emilio; Dalsgaard, Tage; Devol, Allan H.; Ward, Bess B.; Ulloa, Osvaldo; Canfield, Donald E.; Peter Revsbech, Niels
2014-12-01
Highly sensitive STOX O2 sensors were used for determination of in situ O2 distribution in the eastern tropical north and south Pacific oxygen minimum zones (ETN/SP OMZs), as well as for laboratory determination of O2 uptake rates of water masses at various depths within these OMZs. Oxygen was generally below the detection limit (few nmol L-1) in the core of both OMZs, suggesting the presence of vast volumes of functionally anoxic waters in the eastern Pacific Ocean. Oxygen was often not detectable in the deep secondary chlorophyll maximum found at some locations, but other secondary maxima contained up to 0.4 μmol L-1. Directly measured respiration rates were high in surface and subsurface oxic layers of the coastal waters, reaching values up to 85 nmol L-1 O2 h-1. Substantially lower values were found at the depths of the upper oxycline, where values varied from 2 to 33 nmol L-1 O2 h-1. Where secondary chlorophyll maxima were found the rates were higher than in the oxic water just above. Incubation times longer than 20 h, in the all-glass containers, resulted in highly increased respiration rates. Addition of amino acids to the water from the upper oxycline did not lead to a significant initial rise in respiration rate within the first 20 h, indicating that the measurement of respiration rates in oligotrophic Ocean water may not be severely affected by low levels of organic contamination during sampling. Our measurements indicate that aerobic metabolism proceeds efficiently at extremely low oxygen concentrations with apparent half-saturation concentrations (Km values) ranging from about 10 to about 200 nmol L-1.
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A tracer study of ventilation in the Japan/East Sea
NASA Astrophysics Data System (ADS)
Postlethwaite, C. F.; Rohling, E. J.; Jenkins, W. J.; Walker, C. F.
2005-06-01
During the Circulation Research in East Asian Marginal Seas (CREAMS) summer cruises in 1999, a suite of samples was collected for tracer analysis. Oxygen isotopes combined with tritium-helium ventilation timescales and noble gas measurements give unique insights into the ventilation of water masses in the Japan/East Sea (JES). In particular, noble gases and oxygen isotopes are indicators of brine rejection, which may assist in explaining the recent changes observed in the ventilation of the JES. Oxygen isotope data presented here indicate that both thermally driven convection and brine rejection have played significant roles in deep-water formation but that brine rejection is unlikely to be a significant contributor at the moment. A 6-box ventilation model of the JES, calibrated with tritium and helium-3 measurements, performed better when a significant decrease of dense-water formation rates in the mid-1960s was incorporated. However, the model calculations suggest that Japan Sea Intermediate Water formation is still occurring. Subduction of sea-ice melt water may be a significant ventilation mechanism for this water mass, based on an argon saturation minimum at the recently ventilated salinity minimum in the northwestern sector of the JES. The salinity and oxygen isotope budgets imply a potential bottom-water formation rate of 3.97±0.89×10 12 m 3 yr -1 due to brine rejection, which could account for a time averaged fraction of between 25% and 35% of the ventilation of subsurface water formation in the JES.
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Kussman, Barry D.; Wypij, David; Laussen, Peter C.; Soul, Janet S.; Bellinger, David C.; DiNardo, James A.; Robertson, Richard; Pigula, Frank A.; Jonas, Richard A.; Newburger, Jane W.
2010-01-01
Background Near-infrared spectroscopy (NIRS) monitoring of cerebral oxygen saturation (rSO2) has become routine in many centers, but no studies have reported the relationship of intraoperative NIRS to long-term neurodevelopmental outcomes after cardiac surgery. Methods and Results Of 104 infants undergoing biventricular repair without aortic arch reconstruction, 89 (86%) returned for neurodevelopmental testing at age 1 year. The primary NIRS variable was the integrated rSO2 (area under the curve) for rSO2 ≤ 45%; secondary variables were the average and minimum rSO2 by perfusion phase and at specific time points. Psychomotor (PDI) and Mental Development Indexes of the Bayley Scales, head circumference, neurologic examination, and abnormalities on brain MRI did not differ between subjects according to a threshold level for rSO2 of 45%. Lower PDI scores were modestly associated with lower average (r=0.23; P=0.03) and minimum rSO2 (r=0.22; P=0.04) during the 60 minute period following cardiopulmonary bypass (CPB), but not with other perfusion phases. Hemosiderin foci on brain MRI were associated with lower average rSO2 from post-induction to 60 minutes post-CPB (71±10 vs. 78±6%; P=0.01), and lower average rSO2 during the rewarming phase (72±12 vs. 83±9%; P=0.003) and during the 60 minute period following CPB (65±11 vs. 75±10%; P=0.009). In regression analyses adjusting for age ≤ 30 days, PDI score (P=0.02) and brain hemosiderin (P=0.04) remained significantly associated with rSO2 during the 60 minute period following CPB. Conclusions Perioperative periods of diminished cerebral oxygen delivery, as indicated by rSO2, are associated with one-year PDI and brain MRI abnormalities among infants undergoing reparative heart surgery. Clinical Trial Registration Information http://clinicaltrials.gov/ct2/show/NCT00006183 PMID:20606124
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NASA Astrophysics Data System (ADS)
Li, Gang; Yu, Yue; Zhang, Cui; Lin, Ling
2017-09-01
The oxygen saturation is one of the important parameters to evaluate human health. This paper presents an efficient optimization method that can improve the accuracy of oxygen saturation measurement, which employs an optical frequency division triangular wave signal as the excitation signal to obtain dynamic spectrum and calculate oxygen saturation. In comparison to the traditional method measured RMSE (root mean square error) of SpO2 which is 0.1705, this proposed method significantly reduced the measured RMSE which is 0.0965. It is notable that the accuracy of oxygen saturation measurement has been improved significantly. The method can simplify the circuit and bring down the demand of elements. Furthermore, it has a great reference value on improving the signal to noise ratio of other physiological signals.
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Retinal oxygen saturation evaluation by multi-spectral fundus imaging
NASA Astrophysics Data System (ADS)
Khoobehi, Bahram; Ning, Jinfeng; Puissegur, Elise; Bordeaux, Kimberly; Balasubramanian, Madhusudhanan; Beach, James
2007-03-01
Purpose: To develop a multi-spectral method to measure oxygen saturation of the retina in the human eye. Methods: Five Cynomolgus monkeys with normal eyes were anesthetized with intramuscular ketamine/xylazine and intravenous pentobarbital. Multi-spectral fundus imaging was performed in five monkeys with a commercial fundus camera equipped with a liquid crystal tuned filter in the illumination light path and a 16-bit digital camera. Recording parameters were controlled with software written specifically for the application. Seven images at successively longer oxygen-sensing wavelengths were recorded within 4 seconds. Individual images for each wavelength were captured in less than 100 msec of flash illumination. Slightly misaligned images of separate wavelengths due to slight eye motion were registered and corrected by translational and rotational image registration prior to analysis. Numerical values of relative oxygen saturation of retinal arteries and veins and the underlying tissue in between the artery/vein pairs were evaluated by an algorithm previously described, but which is now corrected for blood volume from averaged pixels (n > 1000). Color saturation maps were constructed by applying the algorithm at each image pixel using a Matlab script. Results: Both the numerical values of relative oxygen saturation and the saturation maps correspond to the physiological condition, that is, in a normal retina, the artery is more saturated than the tissue and the tissue is more saturated than the vein. With the multi-spectral fundus camera and proper registration of the multi-wavelength images, we were able to determine oxygen saturation in the primate retinal structures on a tolerable time scale which is applicable to human subjects. Conclusions: Seven wavelength multi-spectral imagery can be used to measure oxygen saturation in retinal artery, vein, and tissue (microcirculation). This technique is safe and can be used to monitor oxygen uptake in humans. This work is original and is not under consideration for publication elsewhere.
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NASA Technical Reports Server (NTRS)
Ramirez, M. P.; Sigaloff, K. C.; Kubatina, L. V.; Donahue, M. A.; Venkatesh, A. K.; Albert, M. S.; ALbert, M. S. (Principal Investigator)
2000-01-01
The physiological effects of various hyperpolarized helium and xenon MRI-compatible breathing protocols were investigated in 17 Sprague-Dawley rats, by continuous monitoring of blood oxygen saturation, heart rate, EKG, temperature and endotracheal pressure. The protocols included alternating breaths of pure noble gas and oxygen, continuous breaths of pure noble gas, breath-holds of pure noble gas for varying durations, and helium breath-holds preceded by two helium rinses. Alternate-breath protocols up to 128 breaths caused a decrease in oxygen saturation level of less than 5% for either helium or xenon, whereas 16 continuous-breaths caused a 31.5% +/- 2.3% decrease in oxygen saturation for helium and a 30.7% +/- 1. 3% decrease for xenon. Breath-hold protocols up to 25 s did not cause the oxygen saturation to fall below 90% for either of the noble gases. Oxygen saturation values below 90% are considered pathological. At 30 s of breath-hold, the blood oxygen saturation dropped precipitously to 82% +/- 0.6% for helium, and to 76.5% +/- 7. 4% for xenon. Breath-holds longer than 10 s preceded by pre-rinses caused oxygen saturation to drop below 90%. These findings demonstrate the need for standardized noble gas inhalation procedures that have been carefully tested, and for continuous physiological monitoring to ensure the safety of the subject. We find short breath-hold and alternate-breath protocols to be safe procedures for use in hyperpolarized noble gas MRI experiments. Copyright 2000 John Wiley & Sons, Ltd.
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Oxygen and the spatial structure of microbial communities.
Fenchel, Tom; Finlay, Bland
2008-11-01
Oxygen has two faces. On one side it is the terminal electron acceptor of aerobic respiration - the most efficient engine of energy metabolism. On the other hand, oxygen is toxic because the reduction of molecular O2 creates reactive oxygen species such as the superoxide anion, peroxide, and the hydroxyl radical. Probably most prokaryotes, and virtually all eukaryotes, depend on oxygen respiration, and we show that the ambiguous relation to oxygen is both an evolutionary force and a dominating factor driving functional interactions and the spatial structure of microbial communities.We focus on microbial communities that are specialised for life in concentration gradients of oxygen, where they acquire the full panoply of specific requirements from limited ranges of PO2, which also support the spatial organisation of microbial communities. Marine and lake sediments provide examples of steep O2 gradients, which arise because consumption or production of oxygen exceeds transport rates of molecular diffusion. Deep lakes undergo thermal stratification in warm waters, resulting in seasonal anaerobiosis below the thermocline, and lakes with a permanent pycnocline often have permanent anoxic deep water. The oxycline is here biologically similar to sediments, and it harbours similar microbial biota, the main difference being the spatial scale. In sediments, transport is dominated by molecular diffusion, and in the water column, turbulent mixing dominates vertical transport. Cell size determines the minimum requirement of aerobic organisms. For bacteria (and mitochondria), the half-saturation constant for oxygen uptake ranges within 0.05-0.1% atmospheric saturation; for the amoeba Acanthamoeba castellanii it is 0.2%, and for two ciliate species measuring around 150 microm, it is 1-2 % atmospheric saturation. Protection against O2 toxicity has an energetic cost that increases with increasing ambient O2 tension. Oxygen sensing seems universal in aquatic organisms. Many aspects of oxygen sensing are incompletely understood, but the mechanisms seem to be evolutionarily conserved. A simple method of studying oxygen preference in microbes is to identify the preferred oxygen tension accumulating in O2 gradients. Microorganisms cannot sense the direction of a chemical gradient directly, so they use other devices to orient themselves. Different mechanisms in different prokaryotic and eukaryotic microbes are described. In O2 gradients, many bacteria and protozoa are vertically distributed according to oxygen tension and they show a very limited range of preferred PO2. In some pigmented protists the required PO2 is contingent on light due to photochemically generated reactive oxygen species. In protists that harbour endosymbiotic phototrophs, orientation towards light is mediated through the oxygen production of their photosynthetic symbionts. Oxygen plays a similar role for the distribution of small metazoans (meiofauna) in sediments, but there is little experimental evidence for this. Thus the oxygenated sediments surrounding ventilated animal burrows provide a special habitat for metazoan meiofauna as well as unicellular organisms.
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Reliability of Near-Infrared Spectroscopy for Determining Muscle Oxygen Saturation during Exercise
ERIC Educational Resources Information Center
Austin, Krista G.; Daigle, Karen A.; Patterson, Patricia; Cowman, Jason; Chelland, Sara; Haymes, Emily M.
2005-01-01
Near-infrared spectroscopy is currently used to assess changes in the oxygen saturation of the muscle during exercise. The primary purpose of this study was to assess the reliability of near-infrared spectroscopy in determining muscle oxygen saturation (StO[subscript 2]) in the vastus lateralis during cycling and the gastrocnemius during running…
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Beetroot juice does not enhance altitude running performance in well-trained athletes.
Arnold, Josh Timothy; Oliver, Samuel James; Lewis-Jones, Tammy Maria; Wylie, Lee John; Macdonald, Jamie Hugo
2015-06-01
We hypothesized that acute dietary nitrate (NO3(-)) provided as concentrated beetroot juice supplement would improve endurance running performance of well-trained runners in normobaric hypoxia. Ten male runners (mean (SD): sea level maximal oxygen uptake, 66 (7) mL·kg(-1)·min(-1); 10 km personal best, 36 (2) min) completed incremental exercise to exhaustion at 4000 m and a 10-km treadmill time-trial at 2500 m simulated altitude on separate days after supplementation with ∼7 mmol NO3(-) and a placebo at 2.5 h before exercise. Oxygen cost, arterial oxygen saturation, heart rate, and ratings of perceived exertion (RPE) were determined during the incremental exercise test. Differences between treatments were determined using means [95% confidence intervals], paired sample t tests, and a probability of individual response analysis. NO3(-) supplementation increased plasma nitrite concentration (NO3(-), 473 (226) nmol·L(-1) vs. placebo, 61 (37) nmol·L(-1), P < 0.001) but did not alter time to exhaustion during the incremental test (NO3(-), 402 (80) s vs. placebo 393 (62) s, P = 0.5) or time to complete the 10-km time-trial (NO3(-), 2862 (233) s vs. placebo, 2874 (265) s, P = 0.6). Further, no practically meaningful beneficial effect on time-trial performance was observed as the 11 [-60 to 38] s improvement was less than the a priori determined minimum important difference (51 s), and only 3 runners experienced a "likely, probable" performance improvement. NO3(-) also did not alter oxygen cost, arterial oxygen saturation, heart rate, or RPE. Acute dietary NO3(-) supplementation did not consistently enhance running performance of well-trained athletes in normobaric hypoxia.
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Pendino, Juan Carlos; Hess, Leonardo; Beltrame, Sergio; Castillo, Gonzalo Aldamiz-Echevarría; Trujillo, John
2017-01-01
This prospective study aimed to characterize the changes in blood lactate concentration and blood oxygen saturation in patients during the immediate postoperative period of cardiac surgery with extracorporeal circulation. Blood samples were collected from 35 patients in a rapid and random order from the arterial line and from the proximal and distal port of a pulmonary artery catheter. The results showed no statistically significant differences between the blood oxygen saturation in the right atrium (72% ± 0.11%) and the blood oxygen saturation in the pulmonary artery (71% ± 0.08%). The blood lactate concentration in the right atrium was 1.7mmol/L ± 0.5mmol/L, and the blood lactate concentration in the pulmonary artery was 1.6mmol/L ± 0.5mmol/L (p < 0.0005). The difference between the blood lactate concentration in the right atrium and the blood lactate concentration in the pulmonary artery might be a consequence of the low blood lactate concentration in the blood from the coronary sinus, as it constitutes an important substrate for the myocardium during this period. The lack of differences between the blood oxygen saturation in the right atrium and the percentage of blood oxygen saturation in the pulmonary artery suggests a lower oxygen extraction by the myocardium given a lower oxygen consumption.
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Effect of commercial airline travel on oxygen saturation in athletes.
Geertsema, C; Williams, A B; Dzendrowskyj, P; Hanna, C
2008-11-01
Aircraft cabins are pressurised to maximum effective altitudes of 2440 metres, resulting in significant decline in oxygen saturation in crew and passengers. This effect has not been studied in athletes. To investigate the degree of decline in oxygen saturation in athletes during long-haul flights. A prospective cross-sectional study. National-level athletes were recruited. Oxygen saturation and heart rate were measured with a pulse oximeter at sea level before departure, at 3 and 7 hours into the flight, and again after arrival at sea level. Aircraft cabin pressure and altitude, cabin fraction of inspired oxygen and true altitude were also recorded. 45 athletes and 18 healthy staff aged between 17 and 70 years were studied on 10 long-haul flights. Oxygen saturation levels declined significantly after 3 hours and 7 hours (3-4%), compared with sea level values. There was an associated drop in cabin pressure and fraction of inspired oxygen, and an increase in cabin altitude. Oxygen saturation declines significantly in athletes during long-haul commercial flights, in response to reduced cabin pressure. This may be relevant for altitude acclimatization planning by athletes, as the time spent on the plane should be considered time already spent at altitude, with associated physiological changes. For flights of 10-13 hours in duration, it will be difficult to arrive on the day of competition to avoid the influence of these changes, as is often suggested by coaches.
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Non-contact measurement of oxygen saturation with an RGB camera
Guazzi, Alessandro R.; Villarroel, Mauricio; Jorge, João; Daly, Jonathan; Frise, Matthew C.; Robbins, Peter A.; Tarassenko, Lionel
2015-01-01
A novel method (Sophia) is presented to track oxygen saturation changes in a controlled environment using an RGB camera placed approximately 1.5 m away from the subject. The method is evaluated on five healthy volunteers (Fitzpatrick skin phenotypes II, III, and IV) whose oxygen saturations were varied between 80% and 100% in a purpose-built chamber over 40 minutes each. The method carefully selects regions of interest (ROI) in the camera image by calculating signal-to-noise ratios for each ROI. This allows it to track changes in oxygen saturation accurately with respect to a conventional pulse oximeter (median coefficient of determination, 0.85). PMID:26417504
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Neshat, Hanieh; Jebreili, Mahnaz; Seyyedrasouli, Aleheh; Ghojazade, Morteza; Hosseini, Mohammad Bagher; Hamishehkar, Hamed
2016-06-01
Different studies have shown that the use of olfactory stimuli during painful medical procedures reduces infants' response to pain. The main purpose of the current study was to investigate the effect of breast milk odor and vanilla odor on premature infants' vital signs including heart rate and blood oxygen saturation during and after venipuncture. A total of 135 preterm infants were randomly selected and divided into three groups of control, vanilla odor, and breast milk odor. Infants in the breast milk group and the vanilla group were exposed to breast milk odor and vanilla odor from 5 minutes prior to sampling until 30 seconds after sampling. The results showed that breast milk odor has a significant effect on the changes of neonatal heart rate and blood oxygen saturation during and after venipuncture and decreased the variability of premature infants' heart rate and blood oxygen saturation. Vanilla odor has no significant effect on premature infants' heart rate and blood oxygen saturation. Breast milk odor can decrease the variability of premature infants' heart rate and blood oxygen saturation during and after venipuncture. Copyright © 2015. Published by Elsevier B.V.
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Tissue oxygen saturation and finger perfusion index in central hypovolemia: influence of pain.
Høiseth, Lars Ø; Hisdal, Jonny; Hoff, Ingrid E; Hagen, Ove A; Landsverk, Svein A; Kirkebøen, Knut A
2015-04-01
Tissue oxygen saturation and peripheral perfusion index are proposed as early indirect markers of hypovolemia in trauma patients. Hypovolemia is associated with increased sympathetic nervous activity. However, many other stimuli, such as pain, also increase sympathetic activity. Since pain is often present in trauma patients, its effect on the indirect measures of hypovolemia needs to be clarified. The aim of this study was, therefore, to explore the effects of hypovolemia and pain on tissue oxygen saturation (measurement sites: cerebral, deltoid, forearm, and thenar) and finger photoplethysmographic perfusion index. Experimental study. University hospital clinical circulation and research laboratory. Twenty healthy volunteers. Central hypovolemia was induced with lower body negative pressure (-60 mm Hg) and pain by the cold pressor test (ice water exposure). Interventions were performed in a 2×2 fashion with the combination of lower body negative pressure or not (normovolemia), and ice water or not (sham). Each subject was thus exposed to four experimental sequences, each lasting for 8 minutes. Measurements were averaged over 30 seconds. For each person and sequence, the minimal value was analyzed. Tissue oxygenation in all measurement sites and finger perfusion index were reduced during hypovolemia/sham compared with normovolemia/sham. Tissue oxygen saturation (except cerebral) and perfusion index were reduced by pain during normovolemia. There was a larger reduction in tissue oxygenation (all measurement sites) and perfusion index during hypovolemia and pain than during normovolemia and pain. Pain (cold pressor test) reduces tissue oxygen saturation in all measurement sites (except cerebral) and perfusion index. In the presence of pain, tissue oxygen saturation and perfusion index are further reduced by hypovolemia (lower body negative pressure, -60 mm Hg). Thus, pain must be considered when evaluating tissue oxygen saturation and perfusion index as markers of hypovolemia in trauma patients.
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Tyrrell, J; Thorn, C; Shore, A; Campbell, S; Curnow, A
2011-12-01
Methylaminolaevulinate (MAL)-photodynamic therapy (PDT) is a successful topical treatment for a number of (pre)cancerous dermatological conditions. In combination, light of the appropriate wavelength, the photosensitizer protoporphyrin IX (PpIX) and tissue oxygen result in the production of singlet oxygen and reactive oxygen species inducing cell death. This study investigates real-time changes in localized tissue blood oxygen saturation and perfusion in conjunction with PpIX fluorescence monitoring for the first time during dermatological MAL-PDT. Oxygen saturation, perfusion and PpIX fluorescence were monitored noninvasively utilizing optical reflectance spectroscopy, laser Doppler perfusion imaging and a fluorescence imaging system, respectively. Patients attending for standard dermatological MAL-PDT were recruited to this ethically approved study and monitored prior to, during and after light irradiation. Significant reductions in mean blood oxygen saturation (P < 0·005) and PpIX fluorescence (P < 0·001) were observed within the first minute of irradiation (4·75 J cm(-2) ) while, in contrast, perfusion was observed to increase significantly (P < 0·01) during treatment. The changes in oxygen saturation and PpIX fluorescence were positively correlated during the initial phase of treatment (r(2) = 0·766). Rapid reductions in the localized blood oxygen saturation have been observed for the first time to occur clinically within the initial minutes of light irradiation and positively correlate with the concurrent PpIX photobleaching. Furthermore, perfusion increases, suggesting that the microvasculature compensates for the PDT-induced oxygen depletion. © 2011 The Authors. BJD © 2011 British Association of Dermatologists 2011.
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Oxygen targeting in preterm infants using the Masimo SET Radical pulse oximeter
Johnston, Ewen D; Boyle, Breidge; Juszczak, Ed; King, Andy; Brocklehurst, Peter; Stenson, Ben J
2011-01-01
Background A pretrial clinical improvement project for the BOOST-II UK trial of oxygen saturation targeting revealed an artefact affecting saturation profiles obtained from the Masimo Set Radical pulse oximeter. Methods Saturation was recorded every 10 s for up to 2 weeks in 176 oxygen dependent preterm infants in 35 UK and Irish neonatal units between August 2006 and April 2009 using Masimo SET Radical pulse oximeters. Frequency distributions of % time at each saturation were plotted. An artefact affecting the saturation distribution was found to be attributable to the oximeter's internal calibration algorithm. Revised software was installed and saturation distributions obtained were compared with four other current oximeters in paired studies. Results There was a reduction in saturation values of 87–90%. Values above 87% were elevated by up to 2%, giving a relative excess of higher values. The software revision eliminated this, improving the distribution of saturation values. In paired comparisons with four current commercially available oximeters, Masimo oximeters with the revised software returned similar saturation distributions. Conclusions A characteristic of the software algorithm reduces the frequency of saturations of 87–90% and increases the frequency of higher values returned by the Masimo SET Radical pulse oximeter. This effect, which remains within the recommended standards for accuracy, is removed by installing revised software (board firmware V4.8 or higher). Because this observation is likely to influence oxygen targeting, it should be considered in the analysis of the oxygen trial results to maximise their generalisability. PMID:21378398
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Oxygen targeting in preterm infants using the Masimo SET Radical pulse oximeter.
Johnston, Ewen D; Boyle, Breidge; Juszczak, Ed; King, Andy; Brocklehurst, Peter; Stenson, Ben J
2011-11-01
A pretrial clinical improvement project for the BOOST-II UK trial of oxygen saturation targeting revealed an artefact affecting saturation profiles obtained from the Masimo Set Radical pulse oximeter. Saturation was recorded every 10 s for up to 2 weeks in 176 oxygen dependent preterm infants in 35 UK and Irish neonatal units between August 2006 and April 2009 using Masimo SET Radical pulse oximeters. Frequency distributions of % time at each saturation were plotted. An artefact affecting the saturation distribution was found to be attributable to the oximeter's internal calibration algorithm. Revised software was installed and saturation distributions obtained were compared with four other current oximeters in paired studies. There was a reduction in saturation values of 87-90%. Values above 87% were elevated by up to 2%, giving a relative excess of higher values. The software revision eliminated this, improving the distribution of saturation values. In paired comparisons with four current commercially available oximeters, Masimo oximeters with the revised software returned similar saturation distributions. A characteristic of the software algorithm reduces the frequency of saturations of 87-90% and increases the frequency of higher values returned by the Masimo SET Radical pulse oximeter. This effect, which remains within the recommended standards for accuracy, is removed by installing revised software (board firmware V4.8 or higher). Because this observation is likely to influence oxygen targeting, it should be considered in the analysis of the oxygen trial results to maximise their generalisability.
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Relating oxygen partial pressure, saturation and content: the haemoglobin-oxygen dissociation curve.
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.
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Uyar, Meral; Davutoğlu, Vedat; Aydın, Neriman; Filiz, Ayten
2013-05-01
The aim of this study is to compare metabolic syndrome with syndrome Z growing epidemic in terms of risk factors, demographic variables, and gender differences in our large cohort at southeastern area in Turkey. Data of patients admitted to sleep clinic in University of Gaziantep from January 2006 to January 2011 were retrospectively evaluated. ATP III and JNC 7 were used for defining metabolic syndrome and hypertension. Data of 761 patients were evaluated. Hypertension, diabetes mellitus, coronary artery disease, pulmonary hypertension, and left ventricular hypertrophy were more common in patients with syndrome Z than in patients without metabolic syndrome. Age, waist/neck circumferences, BMI, triglyceride, glucose, and Epworth sleepiness scale score were detected higher, whereas the minimum oxygen saturation during sleep was lower in patients with syndrome Z. Metabolic syndrome was more common in sleep apneic subjects than in controls (58 versus 30 %). Female sleep apneics showed higher rate of metabolic syndrome than those of males (74 versus 52 %). Hypertension, diabetes mellitus, coronary artery disease, and left ventricular hypertrophy were detected higher in males with syndrome Z than in males without metabolic syndrome. Snoring and excessive daytime sleepiness were detected higher in females with syndrome Z than in females without metabolic syndrome. Systemic/pulmonary hypertension, diabetes mellitus, and left ventricular hypertrophy were more common in females with syndrome Z than in females without metabolic syndrome. Complaints of headache and systemic/pulmonary hypertension were more common among females than males with syndrome Z. Female syndrome Z patients had lower minimum oxygen saturation than male patients with syndrome Z. Metabolic syndrome in sleep apneic patients is more prevalent than in controls. All metabolic syndrome parameters were significantly different among obstructive sleep apneic patients with respect to gender with more severe coronary risk factors in males.
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14 CFR 25.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Minimum mass flow of supplemental oxygen... § 25.1443 Minimum mass flow of supplemental oxygen. (a) If continuous flow equipment is installed for use by flight crewmembers, the minimum mass flow of supplemental oxygen required for each crewmember...
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14 CFR 25.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Minimum mass flow of supplemental oxygen... § 25.1443 Minimum mass flow of supplemental oxygen. (a) If continuous flow equipment is installed for use by flight crewmembers, the minimum mass flow of supplemental oxygen required for each crewmember...
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14 CFR 25.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Minimum mass flow of supplemental oxygen... § 25.1443 Minimum mass flow of supplemental oxygen. (a) If continuous flow equipment is installed for use by flight crewmembers, the minimum mass flow of supplemental oxygen required for each crewmember...
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14 CFR 25.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Minimum mass flow of supplemental oxygen... § 25.1443 Minimum mass flow of supplemental oxygen. (a) If continuous flow equipment is installed for use by flight crewmembers, the minimum mass flow of supplemental oxygen required for each crewmember...
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NASA Technical Reports Server (NTRS)
Soyemi, Olusola O. (Inventor); Soller, Babs R. (Inventor); Yang, Ye (Inventor)
2009-01-01
Methods and systems for calculating tissue oxygenation, e.g., oxygen saturation, in a target tissue are disclosed. In some embodiments, the methods include: (a) directing incident radiation to a target tissue and determining reflectance spectra of the target tissue by measuring intensities of reflected radiation from the target tissue at a plurality of radiation wavelengths; (b) correcting the measured intensities of the reflectance spectra to reduce contributions thereto from skin and fat layers through which the incident radiation propagates; (c) determining oxygen saturation in the target tissue based on the corrected reflectance spectra; and (d) outputting the determined value of oxygen saturation.
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Grillitsch, Sandra; Medgyesy, Nikolaus; Schwerte, Thorsten; Pelster, Bernd
2005-01-01
Several studies suggest that during early larval development of lower vertebrates convective blood flow is not essential to supply oxygen to the tissues, but information about the oxygenation status of larvae during the time of cutaneous respiration is still missing. If convective oxygen transport contributes to the oxygen supply to tissues, venous blood in the central circulatory system should be partly deoxygenated, and hyperoxia should increase the oxygen saturation of the hemoglobin. To analyze the changes in hemoglobin oxygen saturation induced by hyperoxic incubation, zebrafish larvae were incubated in a tiny chamber between polytetrafluoroethylene membranes (Teflon), so that the oxygen supply could be rapidly modified. Hemoglobin oxygen saturation was measured in vivo by combining video imaging techniques with a spectrophotometrical analysis of hemoglobin light absorption at specific wavelengths for maximal absorption of oxygenated and deoxygenated blood (413 nm and 431 nm, respectively) under normoxic conditions and after a 10 min period of hyperoxia (P(O(2))=100 kPa), assuming that at a P(O(2)) of 100 kPa the hemoglobin is fully saturated. The results demonstrated that red blood cell oxygenation of zebrafish larvae at 4 days post fertilization (d.p.f.), 5 d.p.f. and 12 d.p.f. could be increased by hyperoxia. The data suggest that at the time of yolk sac degradation (i.e. 4 d.p.f. and 5 d.p.f.), when the total surface area of the animal is reduced, bulk diffusion of oxygen may not be sufficient to prevent a partial deoxygenation of the hemoglobin. The decrease in hemoglobin oxygenation observed at 12 d.p.f. confirms earlier studies indicating that at 12-14 d.p.f., convective oxygen transport becomes necessary to ensure oxygen supply to the growing tissues.
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Mirle, Elisabeth; Wogatzki, Anna; Kunzmann, Robert; Schoenfelder, Axel M; Litzke, Lutz F
2017-01-01
The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative amount of haemoglobin were measured intraoperatively via laser Doppler and white light spectroscopy (O2C, oxygen to see, LEA Medizintechnik) at six measuring points (MPs) in small and large intestines. Furthermore, the IW thickness was measured ultrasonographically. Nine of 22 horses had an increased small IW thickness greater than 4 mm (Freeman 2002, Scharner and others 2002, le Jeune and Whitcomb 2014) at measuring point 1 (MP1) (strangulated segment), four horses had a thickened bowel wall at measuring point 3 (MP3) (poststenotic) and one at measuring point 2 (MP2). The oxygen saturation was 0 at MP1 in six horses, at MP3 in two horses and at MP2 (prestenotic) in one. Oxygen saturation and small IW thickness were independent of each other at MP1 and MP2. At MP3, the two parameters were negatively correlated. In summary, it is not possible to draw conclusions about oxygen saturation based on IW thickness. PMID:28761667
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Mirle, Elisabeth; Wogatzki, Anna; Kunzmann, Robert; Schoenfelder, Axel M; Litzke, Lutz F
2017-01-01
The surgical evaluation of haemorrhagic infarcted intestine and the decision for or against bowel resection require a lot of experience and are subjective. The aim of this prospective, clinical study was to examine the correlation between oxygen saturation and small intestinal wall (IW) thickness, using two objective methods. In 22 colicky horses, the blood flow, oxygen saturation and relative amount of haemoglobin were measured intraoperatively via laser Doppler and white light spectroscopy (O2C, oxygen to see, LEA Medizintechnik) at six measuring points (MPs) in small and large intestines. Furthermore, the IW thickness was measured ultrasonographically. Nine of 22 horses had an increased small IW thickness greater than 4 mm (Freeman 2002, Scharner and others 2002, le Jeune and Whitcomb 2014) at measuring point 1 (MP1) (strangulated segment), four horses had a thickened bowel wall at measuring point 3 (MP3) (poststenotic) and one at measuring point 2 (MP2). The oxygen saturation was 0 at MP1 in six horses, at MP3 in two horses and at MP2 (prestenotic) in one. Oxygen saturation and small IW thickness were independent of each other at MP1 and MP2. At MP3, the two parameters were negatively correlated. In summary, it is not possible to draw conclusions about oxygen saturation based on IW thickness.
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Dynamic Determination of Oxygenation and Lung Compliance in Murine Pneumonectomy
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
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Blood oxygen saturation of frozen tissue determined by hyper spectral imaging
NASA Astrophysics Data System (ADS)
Braaf, Boy; Nadort, Annemarie; Faber, Dirk; ter Wee, Rene; van Leeuwen, Ton; Aalders, Maurice
2008-02-01
A method is proposed for determining blood oxygen saturation in frozen tissue. The method is based on a spectral camera system equipped with an Acoustic-Optical-Tuneable-Filter. The HSI-setup is validated by measuring series of unfrozen and frozen samples of a hemoglobin-solution, a hemoglobin-intralipid mixture and whole blood with varying oxygen saturation. The theoretically predicted linear relation between oxygen saturation and absorbance was observed in both the frozen sample series and the unfrozen series. In a final proof of principal, frozen myocardial tissue was measured. Higher saturation values were recorded for ventricle and atria tissue compared to the septum and connective tissue. These results are not validated by measurements with another method. The formation of methemoglobin during freezing and the presence of myoglobin in the tissue turned out to be possible sources of error.
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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.
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Luttmann-Gibson, Heike; Sarnat, Stefanie Ebelt; Suh, Helen H.; Coull, Brent A.; Schwartz, Joel; Zanobetti, Antonella; Gold, Diane R.
2014-01-01
Objective We examine whether ambient air pollution is associated with oxygen saturation in 32 elderly subjects in Steubenville. Methods We used linear mixed models to examine the effects of fine particles (PM2.5), sulfate (SO42-), elemental carbon (EC), and gases on median oxygen saturation. Results An interquartile range (IQR) increase of 13.4 μg/m3 in PM2.5 on the previous day was associated with a decrease of -0.18% (95% CI: -0.31 to -0.06), and a 5.1 μg/m3 IQR increase in SO42- on the previous day was associated with a decrease of -0.16% (95% CI: -0.27 to -0.04) in oxygen saturation during the initial 5-min rest period of the protocol. Conclusions Increased exposure to air pollution, including the non-traffic pollutant SO42- from industrial sources, led to changes in oxygen saturation that may reflect particle-induced pulmonary inflammatory or vascular responses. PMID:24451609
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Luttmann-Gibson, Heike; Sarnat, Stefanie Ebelt; Suh, Helen H; Coull, Brent A; Schwartz, Joel; Zanobetti, Antonella; Gold, Diane R
2014-02-01
We examine whether ambient air pollution is associated with oxygen saturation in 32 elderly subjects in Steubenville, Ohio. We used linear mixed models to examine the effects of fine particulate matter less than 2.5 μm (PM(2.5)), sulfate (SO(4)(-2)), elemental carbon, and gases on median oxygen saturation. An interquartile range increase of 13.4 μg/m in PM(2.5) on the previous day was associated with a decrease of -0.18% (95% confidence interval: -0.31 to -0.06) and a 5.1 μg/m(3) interquartile range increase in SO(4)(-2) on the previous day was associated with a decrease of -0.16% (95% confidence interval: -0.27 to -0.04) in oxygen saturation during the initial 5-minute rest period of the protocol. Increased exposure to air pollution, including the nontraffic pollutant SO(4)(-2) from industrial sources, led to changes in oxygen saturation that may reflect particle-induced pulmonary inflammatory or vascular responses.
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Cho, Ah-Reum; Kwon, Jae-Young; Kim, Choongrak; Hong, Jung-Min; Kang, Christine
2017-04-01
Near-infrared spectroscopy sensors often cannot be attached at the commercially recommended locations because combined use of neurological monitoring systems is common during on-pump cardiac surgery. The primary purpose of this study was to compare the incidence of regional cerebral oxygen desaturation and regional cerebral oxygen saturation values detected using near-infrared spectroscopy between the upper and lower forehead during on-pump cardiac surgery. A prospective observational study was conducted with 25 adult patients scheduled for elective on-pump cardiac surgery. Regional cerebral oxygen saturations at the left upper and lower forehead and other clinical measurements were monitored intraoperatively. McNemar's test was used to analyze differences in the incidence of cerebral regional oxygen desaturation between the left upper and lower forehead. Two-way repeated measures ANOVA with post hoc Bonferroni correction was used to compare the regional cerebral oxygen saturation at each time point. There was a significantly higher incidence of regional cerebral oxygen desaturation at the upper than lower forehead only at 1 h after initiation of aortic cross-clamping. There were significant differences between the left upper and lower regional cerebral oxygen saturation values throughout the observation period. Regional cerebral oxygen saturation was significantly lower at the upper than lower forehead during on-pump cardiac surgery. However, disagreements in detection of cerebral regional oxygen desaturation were only significant at 1 h after initiation of aortic cross-clamping. WHO-ICTRP, Clinical Research Information Service (CRiS). ID: KCT0000971. URL: https://cris.nih.go.kr/cris/search/search_result_st01_en.jsp?seq=3678&type=my .
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NASA Astrophysics Data System (ADS)
Xu, Xiaorong; Zhu, Wen; Padival, Vikram; Xia, Mengna; Cheng, Xuefeng; Bush, Robin; Christenson, Linda; Chan, Tim; Doherty, Tim; Iatridis, Angelo
2003-07-01
Photonify"s tissue spectrometer uses Near-Infrared Spectroscopy for real-time, noninvasive measurement of hemoglobin concentration and oxygen saturation [SO2] of biological tissues. The technology was validated by a series of ex vivo and animal studies. In the ex vivo experiment, a close loop blood circulation system was built, precisely controlling the oxygen saturation and the hemoglobin concentration of a liquid phantom. Photonify"s tissue spectrometer was placed on the surface of the liquid phantom for real time measurement and compared with a gas analyzer, considered the gold standard to measure oxygen saturation and hemoglobin concentration. In the animal experiment, the right hind limb of each dog accepted onto the study was surgically removed. The limb was kept viable by connecting the femoral vein and artery to a blood-primed extracorporeal circuit. Different concentrations of hemoglobin were obtained by adding designated amount of saline solution into the perfusion circuit. Photonify"s tissue spectrometers measured oxygen saturation and hemoglobin concentration at various locations on the limb and compared with gas analyzer results. The test results demonstrated that Photonify"s tissue spectrometers were able to detect the relative changes in tissue oxygen saturation and hemoglobin concentration with a high linear correlation compared to the gas analyzer
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Lower early postnatal oxygen saturation target and risk of ductus arteriosus closure failure.
Inomata, Kei; Taniguchi, Shinji; Yonemoto, Hiroki; Inoue, Takeshi; Kawase, Akihiko; Kondo, Yuichi
2016-11-01
Early postnatal hyperoxia is a major risk factor for retinopathy of prematurity (ROP) in extremely premature infants. To reduce the occurrence of ROP, we adopted a lower early postnatal oxygen saturation (SpO 2 ) target range (85-92%) from April 2011. Lower SpO 2 target range, however, may lead to hypoxemia and an increase in the risk of ductus arteriosus (DA) closure failure. The aim of this study was therefore to determine whether a lower SpO 2 target range, during the early postnatal stage, increases the risk of DA closure failure. Infants born at <28 weeks' gestation were enrolled in this study. Oxygen saturation target range during the first postnatal 72 h was 84-100% in study period 1 and 85-92% in period 2. Eighty-two infants were included in period 1, and 61 were included in period 2. The lower oxygen saturation target range increased the occurrence of hypoxemia during the first postnatal 72 h. Prevalence of DA closure failure in period 2 (21%) was significantly higher than that in period 1 (1%). On multivariate logistic regression analysis, the lower oxygen saturation target range was an independent risk factor for DA closure failure. Lower early postnatal oxygen saturation target range increases the risk of DA closure failure. © 2016 Japan Pediatric Society.
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Wang, Xiao-Hui; Peng, Hong-Shang; Cheng, Kun; Liu, Xiao-Ming; Liu, Yuan-An; Yang, Wei
2018-04-27
Ratiometric fluorescent nanoparticles (NPs) under two-photon excitation are successfully developed for sensing dissolved oxygen. The NPs comprise the oxygen probe Pt(II)-porphyrins (PtTFPP) and fluorescent organic semiconducting polymer (PFO). PFO polymer acts as both a two-photon antenna and a reference dye, while PtTFPP absorbs the photonic energy transferred by the PFO under two-photon excitation at 740 nm to sense oxygen. The red fluorescence of PtTFPP is sensitive to oxygen with a quenching response of 88% from nitrogen saturation to oxygen saturation, and PFO gives oxygen-insensitive referenced blue fluorescence. The fluorescence quenching of the NPs against oxygen at two-photon excitation follows a linear Stern-Volmer behavior. The nanosensors exhibit low cytotoxic effects as well as effortless cellular uptake. When incorporated into cells, the ratio of the signals increases up to about 500% from oxygen-saturated to oxygen-free environment.
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Jørgensen, Christina Mørup; Bek, Toke
2017-06-01
Diabetic retinopathy is characterised by morphological lesions in the ocular fundus related to disturbances in retinal blood flow. The two vision threatening forms of retinopathy show specific patterns of distribution of retinal lesions with proliferative diabetic retinopathy (PDR) developing secondary to ischaemia and hypoxia in the retinal periphery and diabetic maculopathy (DM) developing secondary to hyperperfusion and increased vascular permeability in the macular area. These differences in the distribution of retinal lesions might be reflected in regional differences in oxygen saturation in the larger retinal vessels. Dual-wavelength retinal oximetry was performed in 30 normal persons, 30 patients with DM and 30 patients with PDR, and the oxygen saturation was measured in peripapillary vessels supplying the four retinal quadrants and in branches from the upper temporal arcades supplying, respectively, the macular area and the retinal periphery. The overall oxygen saturation was significantly higher in diabetic patients than in normal persons and the arteriovenous (AV) saturation difference significantly lower in the patients with DM. The regional variation in oxygen saturation was similar in the three studied groups with a decreasing saturation from the upper nasal through the lower nasal, lower temporal and the upper temporal peripapillary vessels, and with a significantly higher oxygen saturation in venules draining the macular area than in venules draining the retinal periphery. The regional differences in retinal lesions in vision threatening diabetic retinopathy are not reflected in regional differences in the oxygen saturation of larger retinal vessels. The development of vision threatening diabetic retinopathy depends on other factors, such as, for example, regional differences in the retinal microcirculation. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.
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Schmidt, Barbara; Whyte, Robin K; Asztalos, Elizabeth V; Moddemann, Diane; Poets, Christian; Rabi, Yacov; Solimano, Alfonso; Roberts, Robin S
2013-05-22
The goal of oxygen therapy is to deliver sufficient oxygen to the tissues while minimizing oxygen toxicity and oxidative stress. It remains uncertain what values of arterial oxygen saturations achieve this balance in preterm infants. To compare the effects of targeting lower or higher arterial oxygen saturations on the rate of death or disability in extremely preterm infants. Randomized, double-blind trial in 25 hospitals in Canada, the United States, Argentina, Finland, Germany, and Israel in which 1201 infants with gestational ages of 23 weeks 0 days through 27 weeks 6 days were enrolled within 24 hours after birth between December 2006 and August 2010. Follow-up assessments began in October 2008 and ended in August 2012. Study participants were monitored until postmenstrual ages of 36 to 40 weeks with pulse oximeters that displayed saturations of either 3% above or below the true values. Caregivers adjusted the concentration of oxygen to achieve saturations between 88% and 92%, which produced 2 treatment groups with true target saturations of 85% to 89% (n = 602) or 91% to 95% (n = 599). Alarms were triggered when displayed saturations decreased to 86% or increased to 94%. The primary outcome was a composite of death, gross motor disability, cognitive or language delay, severe hearing loss, or bilateral blindness at a corrected age of 18 months. Secondary outcomes included retinopathy of prematurity and brain injury. Of the 578 infants with adequate data for the primary outcome who were assigned to the lower target range, 298 (51.6%) died or survived with disability compared with 283 of the 569 infants (49.7%) assigned to the higher target range (odds ratio adjusted for center, 1.08; 95% CI, 0.85 to 1.37; P = .52). The rates of death were 16.6% for those in the 85% to 89% group and 15.3% for those in the 91% to 95% group (adjusted odds ratio, 1.11; 95% CI, 0.80 to 1.54; P = .54). Targeting lower saturations reduced the postmenstrual age at last use of oxygen therapy (adjusted mean difference, -0.8 weeks; 95% CI, -1.5 to -0.1; P = .03) but did not alter any other outcomes. In extremely preterm infants, targeting oxygen saturations of 85% to 89% compared with 91% to 95% had no significant effect on the rate of death or disability at 18 months. These results may help determine the optimal target oxygen saturation. ISRCTN Identifier: 62491227; ClinicalTrials.gov Identifier: NCT00637169.
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Petri, M; Stoffels, I; Jose, J; Leyh, J; Schulz, A; Dissemond, J; Schadendorf, D; Klode, J
2016-02-01
To use a non-invasive measurement of oxygen saturation in chronic leg ulcers after the application of a topical haemoglobin spray to investigate if photoacoustic tomography is able to measure the oxygen saturation and if the stimulated oxygen increase can be demonstrated. We measured the oxygen saturation of the ulcer tissue in five patients with chronic leg ulcers before application and 5 and 20 minutes after application of the haemoglobin spray, using photoacoustic tomography as a new method to assess oxygenation in real-time. The average oxygen saturation showed a significant increase from 56.4% before to 69% (p=0.042) after 5 minutes and 78.8% (p=0.043) 20 minutes after the topical haemoglobin application. The oxygenation status of chronic, hard-to-heal wounds is gaining increasing interest in modern wound therapy. Topical haemoglobin spray is a new and effective method to increase the oxygenation in the ulcer tissue, but until now the link between clinical results and the mode of action was unclear. We were able to show for the first time that the use of a topical haemoglobin spray leads to an increase in oxygen saturation in vivo using photoacoustic tomography. Joachim Dissemond received financial support from the company SastoMed for several scientific projects as well as for lectures and as an advisor. The haemoglobin spray was provided by SastoMed GmbH (Georgsmarienhütte, Germany).
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Rath, Chandra; Kluckow, Martin
2016-03-01
Compare the oxygen saturation profiles before discharge of neonates born extremely preterm (<28 weeks), now at term equivalent age, with healthy term neonates and assess the impact of feeding on this profile in each group. We prospectively evaluated and compared the oxygen saturation profile in 15 very low birthweight infants at term equivalent age, ready to be discharged home without any oxygen and 15 term newborns after 48 hours of life. We also evaluated and compared the saturations of these two groups during a one-hour period during and after feeding. Term equivalent preterm and term infants spent median 3% and 0%, respectively, of the time below 90% in a 12-hour saturation-recording period. Term infants spent a median 0.26% and 0.65% of the time in <90% saturation during feed time and no feed time, respectively. In contrast, preterm infants spent significantly more time <90% saturation (3.47% and 3.5% during feed time and no feed time, respectively). Term equivalent preterm infants spent significantly more time in a saturation range <90% compared to term infants. Feeding had little effect on saturation profile overall within each group. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.
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Cognition Effects of Low-Grade Hypoxia
2016-07-01
oxygen con- tent and/or cerebral blood flow . Hypocapnia shifts the oxygen dissociation curve to the left, resulting in an increase in blood oxygen ...pressure chamber in a balanced design. Oxygen saturation, heart rate, and cognitive performance on seven different cognitive tasks were measured. In...addition, subjects indicated their symptoms from a 33-item subjective symptom survey. As designed, oxygen saturation decreased and heart rate increased
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Hypoxia, Monitoring, and Mitigation System
2014-05-01
indicators based on measured and predicted data. Given the beat-to-beat method in which oxygen saturation is measured via a pulse oximeter , a certain...saturation sample values are far below what would be trusted on a pulse oximeter . No indication was given after oxygen mask placement on subjective...determined using a pulse oximeter for continuous monitoring of arterial oxygen saturation (SaO2) in 95 ASA class I or II adult patients breathing room
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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
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Spatio-Temporal Patterns in Rhizosphere Oxygen Profiles in the Emergent Plant Species Acorus calamus
Wenlin, Wang; Ruiming, Han; Yinjing, Wan; Bo, Liu; Xiaoyan, Tang; Bin, Liang; Guoxiang, Wang
2014-01-01
Rhizosphere oxygen profiles are the key to understanding the role of wetland plants in ecological remediation. Though in situ determination of the rhizosphere oxygen profiles has been performed occasionally at certain growing stages within days, comprehensive study on individual roots during weeks is still missing. Seedlings of Acorus calamus, a wetland monocot, were cultivated in silty sediment and the rhizosphere oxygen profiles were characterized at regular intervals, using micro-optodes to examine the same root at four positions along the root axis. The rhizosphere oxygen saturation culminated at 42.9% around the middle part of the root and was at its lowest level, 3.3%, at the basal part of the root near the aboveground portion. As the plant grew, the oxygen saturation at the four positions remained nearly constant until shoot height reached 15 cm. When shoot height reached 60 cm, oxygen saturation was greatest at the point halfway along the root, followed by the point three-quarters of the way down the root, the tip of the root, and the point one-quarter of the way down. Both the internal and rhizosphere oxygen saturation steadily increased, as did the thickness of stably oxidized microzones, which ranged from 20 µm in younger seedlings to a maximum of 320 µm in older seedlings. The spatial patterns of rhizosphere oxygen profiles in sediment contrast with those from previous studies on radial oxygen loss in A. calamus that used conventional approaches. Rhizosphere oxygen saturation peaked around the middle part of roots and the thickness of stably oxidized zones increased as the roots grew. PMID:24866504
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NASA Astrophysics Data System (ADS)
Hammer, M.; Riemer, T.; Vilser, W.; Gehlert, S.; Schweitzer, D.
2009-02-01
The oxygen saturation of blood inside retinal vessels is an essential measure for the estimation of oxygen supply to the tissue as well as its oxygen consumption. In the current approach, the blood oxygenation is measured by a dual-wavelength technique. Using a fundus camera, equipped with a special dual wavelength transmission filter and a color CCD camera, two monochromatic fundus images at 548 nm and 610 nm were recorded simultaneously. The optical densities of retinal vessels for both wavelengths and their ratio, which is known to be proportional to the oxygen saturation, were calculated. From a health control population, mean arterial and venous oxygen saturations were measured of 98+/-10.1% and 65+/-11.7% with reproducibility of 2.52% and 3.25% respectively. In 10 patients with arterial occlusion, a reduction of the arterial oxygen saturation to 78 +/-17% (mean +/- standard deviation, branch arterial occlusion) and 91+/-11% (central arterial occlusion) respectively was found in the occluded vessel. After 5 days on pentoxifilin therapy, the arterial saturation increased to an average of 93+/-12% or 103 +/-6% respectively. In 70 eyes of 42 patients suffering from diabetic retinopathy, an increase of the venous oxygen saturation with the severity of the retinopathy was found (mild nonproliferative retinopathy: 68.4+/-8.2%, moderate non-proliferative retinopathy: 70.5+/-6.8%, severe non-proliferative retinopathy: 72.4+/-7.6%, proliferative retinopathy 75.7+/-8.3%) due to vessel shunting and diabetic changes of the permeability of vessel walls. These first clinical results demonstrate the ability of an accurate measurement of retinal vessel oxygenation with a very simple setup just requiring a special filter in the illumination path of a fundus camera and dedicated software.
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Multi-spectral imaging of oxygen saturation
NASA Astrophysics Data System (ADS)
Savelieva, Tatiana A.; Stratonnikov, Aleksander A.; Loschenov, Victor B.
2008-06-01
The system of multi-spectral imaging of oxygen saturation is an instrument that can record both spectral and spatial information about a sample. In this project, the spectral imaging technique is used for monitoring of oxygen saturation of hemoglobin in human tissues. This system can be used for monitoring spatial distribution of oxygen saturation in photodynamic therapy, surgery or sports medicine. Diffuse reflectance spectroscopy in the visible range is an effective and extensively used technique for the non-invasive study and characterization of various biological tissues. In this article, a short review of modeling techniques being currently in use for diffuse reflection from semi-infinite turbid media is presented. A simple and practical model for use with a real-time imaging system is proposed. This model is based on linear approximation of the dependence of the diffuse reflectance coefficient on relation between absorbance and reduced scattering coefficient. This dependence was obtained with the Monte Carlo simulation of photon propagation in turbid media. Spectra of the oxygenated and deoxygenated forms of hemoglobin differ mostly in the red area (520 - 600 nm) and have several characteristic points there. Thus four band-pass filters were used for multi-spectral imaging. After having measured the reflectance, the data obtained are used for fitting the concentration of oxygenated and free hemoglobin, and hemoglobin oxygen saturation.
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Li, Zeng-yong; Dai, Shi-xun; Zhang, Xiao-yin; Li, Yue; Yu, Xing-xin
2010-01-01
The objective of the present study is to assess the cerebral saturation under driver fatigue based on the near infrared spectroscopy (NIRS) signals. Twenty healthy male subjects were randomly divided into two groups: A-group (study group) and B-group (control group). All subjects were required to be well rested before the experiment. In A-group the subjects were required to perform the simulated driving task for 3 hours. Cerebral oxygenation signal was monitored for 20 minutes prior to and after the prescribed task period from the left frontal lobe. The results show that cerebral oxygen saturation was found to be significantly lower following 3-hour driving in the task group compared to that in the control group (F = 15.92, p < 0.001). Also a significant difference in selective reaction time was observed between the task group and control group during the post task period (p = 0.021). These findings showed that the cerebral blood oxygen saturation was closely related to the driver fatigue. The decline of the cerebral oxygen saturation might indicate a reduced cerebral oxygen delivery. This suggests that NIRS could provide a non-invasive method to detect driver fatigue.
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Bouloukaki, Izolde; Tzanakis, Nikolaos; Mermigkis, Charalampos; Giannadaki, Katerina; Moniaki, Violeta; Mauroudi, Eleni; Michelakis, Stylianos; Schiza, Sophia E
2016-05-01
Patients with chronic obstructive pulmonary disease (COPD) have poor sleep quality as a result of various alterations in oxygenation parameters and sleep macro- and micro-architecture. There is a shortage of data to support the efficacy of long-acting inhaled anticholinergic agents in improving these adverse effects, which are known to have a negative impact on clinical outcomes. We aimed to compare the tiotropium Respimat Soft Mist Inhaler and the HandiHaler in terms of their effects on sleeping oxygen saturation (SaO2) and sleep quality in patients with COPD. In a randomized, open-label, parallel-group trial involving 200 patients with mild to moderate COPD (resting arterial oxygen tension >60 mmHg while awake), we compared the effects of 6 months' treatment with the two devices on sleeping SaO2 and sleep quality. Overnight polysomnography and pulmonary function testing were performed at baseline and after 6 months' treatment. A total of 188 patients completed the trial. Both groups showed significant improvement in minimum sleep SaO2 and time of sleep spent with SaO2 below 90 (TST90) compared to baseline. The patients using the Respimat had significantly better TST90 than did those using the HandiHaler. Sleep disturbance was highly variable in these patients, but the sleep stage durations were significantly better in the Respimat group. Sleeping SaO2 can be improved by tiotropium delivered using either the HandiHaler device or the Respimat Soft Mist Inhaler. However, the patients who used the Respimat device had significantly better TST90 and sleep architecture parameters.
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NASA Technical Reports Server (NTRS)
Laing, R. A.; Danisch, L. A.; Young, L. R.
1975-01-01
The Choroidal Eye Oximeter is an electro-optical instrument that noninvasively measures the oxygen saturation of choroidal blood in the back of the human eye by a spectrophotometric method. Since choroidal blood is characteristic of blood which is supplied to the brain, the Choroidal Eye Oximeter can be used to monitor the amount of oxygen which is supplied to the brain under varying external conditions. The instrument consists of two basic systems: the optical system and the electronic system. The optical system produces a suitable bi-chromatic beam of light, reflects this beam from the fundus of the subject's eye, and onto a low-noise photodetector. The electronic system amplifies the weak composite signal from the photodetector, computes the average oxygen saturation from the area of the fundus that was sampled, and displays the value of the computed oxygen saturation on a panel meter.
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Krupatkin, A I
2012-01-01
Laser Doppler flowmetry, laser spectrophotometry of oxygen saturation and fluorescence determination of NAD-H/FAD ratio were carried out at 30 humans in the upper extremity skin zones with and without arteriole-venule anastomoses (AVA). For the first time it was shown that wavelet-analysis of oxygen saturation and microvascular blood flow oscillations was an effective approach to noninvasive estimation of skin oxygen extraction (OE) and oxygen consumption rate (OC). OE = (SaO2--SvO2)/SaO2, where SaO2 (%) and SvO2(%) are the oxygen saturation of arterial and venular blood, correspondingly. If the ratio between amplitudes of cardiac rhythm (Ac, p.u.) and respiratory rhythm (Ar, p.u.) Ac/Ar < or = 1, SvO2 = SO2. In the case of Ac/Ar >1, SvO2 = SO2/(Ac/Ar). OC = Mnutr x (SaO2-SvO2) in p.u. x %O2, where Mnutr--value of nutritive perfusion (p.u.). Mnutr = M/SI, where SI--shunting index of blood flow in microvessels. The values of perfusion, OE and OC were higher in the skin with AVA than in the skin without AVA. The values of perfusion and oxygen saturation were more variable in the skin with AVA. The greatest significance for tissue metabolism have the oxygen diffused from the smallest arterioles and capillaries. The contribution increased to tissue metabolism of total perfusion and of oxygen diffused from arterioles in the conditions of tissue ischemia.
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Retinal oximetry in patients with ischaemic retinal diseases.
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.
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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.
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Agreement of SpO2, SaO2 and ScO2 in anesthetized cynomolgus monkeys (Macaca fascicularis).
Young, Simon S; Skeans, Susan M; Lamca, James E; Chapman, Richard W
2002-07-01
To assess the agreement between three measurements of arterial oxygen saturation (SpO 2 , SaO 2 and ScO 2 ) in anesthetized cynomolgus monkeys. Prospective study. Eleven mature, male cynomolgus monkeys (Macaca fasicularis). Monkeys were anesthetized with intramuscular ketamine followed by intravenous propofol. The trachea of each was intubated and the lungs ventilated. Arterial oxygen saturation was measured with a Nonin 8500 V pulse oximeter, using a lingual clip on the cheek. Arterial blood samples were taken from an indwelling catheter. Inspired oxygen concentration was varied from 12 to 20%, and 88 paired arterial blood samples and saturation measurements were taken. Arterial oxygen saturation in the blood samples was measured using a cooximeter. The saturation was also calculated from the arterial oxygen tension using the Adair equation. The results were compared using Bland and Altman's method. The pulse oximeter readings were 2.7% higher than that of the cooximeter, with a limit of agreement of -3.9 to 9.3%. The pulse oximeter readings were 1.8% higher than the calculated saturation, with a limit of agreement of -6.5% to 10.1%. The cooximeter readings were 0.9% lower than the calculated saturation, with a limit of agreement of -5.6% to 3.8%. The agreement between SpO 2 and other measurements of arterial oxygen saturation in this study is typical for this technique. The bias and limits of agreement are consistent with reports in other species. The Nonin 8500 V is a useful pulse oximeter for clinical use in primates. Copyright © 2002 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Ltd. All rights reserved.
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2013-01-01
vilian trauma systems and in military casualty care rely on standard vital signs (blood pressure, arterial oxygen saturation , heart rate [HR...acting to maintain blood pressure and arterial oxygen saturation (i.e., standard vital signs are not changing) in the presence of re- duced...assessments in austere environments. Profiles of changes in mean arterial pressure (MAP), cardiac output, and venous oxygen saturation during LBNP have been
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Isaza-Restrepo, Andres; Moreno-Mejia, Jose F; Martin-Saavedra, Juan S; Ibañez-Pinilla, Milciades
2017-01-01
There is a well known relationship between hypoperfusion and postoperative complications like anastomotic leak. No studies have been done addressing this relationship in the context of abdominal trauma surgery. Central venous oxygen saturation is an important hypoperfusion marker of potential use in abdominal trauma surgery for identifying the risk of anastomotic leak development. The purpose of this study was to identify the relationship between low values of central venous oxygen saturation and anastomotic leak of gastrointestinal sutures in the postoperative period in abdominal trauma surgery. A cross-sectional prospective study was performed. Patients over 14 years old who required surgical gastrointestinal repair secondary to abdominal trauma were included. Anastomotic leak diagnosis was confirmed through clinical manifestations and diagnostic images or secondary surgery when needed. Central venous oxygen blood saturation was measured at the beginning of surgery through a central catheter. Demographic data, trauma mechanism, anatomic site of trauma, hemoglobin levels, abdominal trauma index, and comorbidities were assessed as secondary variables. Patients who developed anastomotic leak showed lower mean central venous oxygen saturation levels (60.0% ± 2.94%) than those who did not (69.89% ± 7.21%) ( p = 0.010). Central venous oxygen saturation <65% was associated with the development of gastrointestinal leak during postoperative time of patients who underwent surgery secondary to abdominal trauma.
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Single-wavelength functional photoacoustic microscopy in biological tissue.
Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin; Wang, Lihong V
2011-03-01
Recently, we developed a reflection-mode relaxation photoacoustic microscope, based on saturation intensity, to measure picosecond relaxation times using a nanosecond laser. Here, using the different relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, the oxygen saturation was quantified in vivo with single-wavelength photoacoustic microscopy. All previous functional photoacoustic microscopy measurements required imaging with multiple-laser-wavelength measurements to quantify oxygen saturation. Eliminating the need for multiwavelength measurements removes the influence of spectral properties on oxygenation calculations and improves the portability and cost-effectiveness of functional or molecular photoacoustic microscopy.
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Single-wavelength functional photoacoustic microscopy in biological tissue
Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.
2011-01-01
Recently, we developed a reflection-mode relaxation photoacoustic microscope, based on saturation intensity, to measure picosecond relaxation times using a nanosecond laser. Here, using the different relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, the oxygen saturation was quantified in vivo with single-wavelength photoacoustic microscopy. All previous functional photoacoustic microscopy measurements required imaging with multiple laser-wavelength measurements to quantify oxygen saturation. Eliminating the need for multi-wavelength measurements removes the influence of spectral properties on oxygenation calculations and improves the portability and cost-effectiveness of functional or molecular photoacoustic microscopy. PMID:21368977
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Bopp, L; Resplandy, L; Untersee, A; Le Mezo, P; Kageyama, M
2017-09-13
All Earth System models project a consistent decrease in the oxygen content of oceans for the coming decades because of ocean warming, reduced ventilation and increased stratification. But large uncertainties for these future projections of ocean deoxygenation remain for the subsurface tropical oceans where the major oxygen minimum zones are located. Here, we combine global warming projections, model-based estimates of natural short-term variability, as well as data and model estimates of the Last Glacial Maximum (LGM) ocean oxygenation to gain some insights into the major mechanisms of oxygenation changes across these different time scales. We show that the primary uncertainty on future ocean deoxygenation in the subsurface tropical oceans is in fact controlled by a robust compensation between decreasing oxygen saturation (O 2sat ) due to warming and decreasing apparent oxygen utilization (AOU) due to increased ventilation of the corresponding water masses. Modelled short-term natural variability in subsurface oxygen levels also reveals a compensation between O 2sat and AOU, controlled by the latter. Finally, using a model simulation of the LGM, reproducing data-based reconstructions of past ocean (de)oxygenation, we show that the deoxygenation trend of the subsurface ocean during deglaciation was controlled by a combination of warming-induced decreasing O 2sat and increasing AOU driven by a reduced ventilation of tropical subsurface waters.This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'. © 2017 The Author(s).
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NASA Astrophysics Data System (ADS)
Bopp, L.; Resplandy, L.; Untersee, A.; Le Mezo, P.; Kageyama, M.
2017-08-01
All Earth System models project a consistent decrease in the oxygen content of oceans for the coming decades because of ocean warming, reduced ventilation and increased stratification. But large uncertainties for these future projections of ocean deoxygenation remain for the subsurface tropical oceans where the major oxygen minimum zones are located. Here, we combine global warming projections, model-based estimates of natural short-term variability, as well as data and model estimates of the Last Glacial Maximum (LGM) ocean oxygenation to gain some insights into the major mechanisms of oxygenation changes across these different time scales. We show that the primary uncertainty on future ocean deoxygenation in the subsurface tropical oceans is in fact controlled by a robust compensation between decreasing oxygen saturation (O2sat) due to warming and decreasing apparent oxygen utilization (AOU) due to increased ventilation of the corresponding water masses. Modelled short-term natural variability in subsurface oxygen levels also reveals a compensation between O2sat and AOU, controlled by the latter. Finally, using a model simulation of the LGM, reproducing data-based reconstructions of past ocean (de)oxygenation, we show that the deoxygenation trend of the subsurface ocean during deglaciation was controlled by a combination of warming-induced decreasing O2sat and increasing AOU driven by a reduced ventilation of tropical subsurface waters. This article is part of the themed issue 'Ocean ventilation and deoxygenation in a warming world'.
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Non-invasive assessment of cerebral oxygenation: A comparison of retinal and transcranial oximetry
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
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A method of improving sensitivity of carbon/oxygen well logging for low porosity formation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Liu, Juntao; Zhang, Feng; Zhang, Quanying
Carbon/Oxygen (C/O) spectral logging technique has been widely used to determine residual oil saturation and the evaluation of water flooded layer. In order to improve the sensitivity of the technique for low – porosity formation, Gaussian and linear models are applied to fit the peaks of measured spectra to obtain the characteristic coefficients. Standard spectra of carbon and oxygen are combined to establish a new carbon /oxygen value calculation method, and the robustness of the new method is cross – validated with known mixed gamma ray spectrum. Formation models for different porosities and saturations are built using Monte Carlo method.more » The responses of carbon/oxygen which are calculated by conventional energy window method, and the new method is applied to oil saturation under low porosity conditions. The results show the new method can reduce the effects of gamma rays contaminated by the interaction between neutrons and other elements on carbon/oxygen ratio, and therefore can significantly improve the response sensitivity of carbon/oxygen well logging to oil saturation. The new method improves greatly carbon/oxygen well logging in low porosity conditions.« less
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A method of improving sensitivity of carbon/oxygen well logging for low porosity formation
Liu, Juntao; Zhang, Feng; Zhang, Quanying; ...
2016-12-01
Carbon/Oxygen (C/O) spectral logging technique has been widely used to determine residual oil saturation and the evaluation of water flooded layer. In order to improve the sensitivity of the technique for low – porosity formation, Gaussian and linear models are applied to fit the peaks of measured spectra to obtain the characteristic coefficients. Standard spectra of carbon and oxygen are combined to establish a new carbon /oxygen value calculation method, and the robustness of the new method is cross – validated with known mixed gamma ray spectrum. Formation models for different porosities and saturations are built using Monte Carlo method.more » The responses of carbon/oxygen which are calculated by conventional energy window method, and the new method is applied to oil saturation under low porosity conditions. The results show the new method can reduce the effects of gamma rays contaminated by the interaction between neutrons and other elements on carbon/oxygen ratio, and therefore can significantly improve the response sensitivity of carbon/oxygen well logging to oil saturation. The new method improves greatly carbon/oxygen well logging in low porosity conditions.« less
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Vavougios, George D; George D, George; Pastaka, Chaido; Zarogiannis, Sotirios G; Gourgoulianis, Konstantinos I
2016-02-01
Phenotyping obstructive sleep apnea syndrome's comorbidity has been attempted for the first time only recently. The aim of our study was to determine phenotypes of comorbidity in obstructive sleep apnea syndrome patients employing a data-driven approach. Data from 1472 consecutive patient records were recovered from our hospital's database. Categorical principal component analysis and two-step clustering were employed to detect distinct clusters in the data. Univariate comparisons between clusters included one-way analysis of variance with Bonferroni correction and chi-square tests. Predictors of pairwise cluster membership were determined via a binary logistic regression model. The analyses revealed six distinct clusters: A, 'healthy, reporting sleeping related symptoms'; B, 'mild obstructive sleep apnea syndrome without significant comorbidities'; C1: 'moderate obstructive sleep apnea syndrome, obesity, without significant comorbidities'; C2: 'moderate obstructive sleep apnea syndrome with severe comorbidity, obesity and the exclusive inclusion of stroke'; D1: 'severe obstructive sleep apnea syndrome and obesity without comorbidity and a 33.8% prevalence of hypertension'; and D2: 'severe obstructive sleep apnea syndrome with severe comorbidities, along with the highest Epworth Sleepiness Scale score and highest body mass index'. Clusters differed significantly in apnea-hypopnea index, oxygen desaturation index; arousal index; age, body mass index, minimum oxygen saturation and daytime oxygen saturation (one-way analysis of variance P < 0.0001). Binary logistic regression indicated that older age, greater body mass index, lower daytime oxygen saturation and hypertension were associated independently with an increased risk of belonging in a comorbid cluster. Six distinct phenotypes of obstructive sleep apnea syndrome and its comorbidities were identified. Mapping the heterogeneity of the obstructive sleep apnea syndrome may help the early identification of at-risk groups. Finally, determining predictors of comorbidity for the moderate and severe strata of these phenotypes implies a need to take these factors into account when considering obstructive sleep apnea syndrome treatment options. © 2015 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.
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Yapakçı, Ece; Ecevit, Ayşe; İnce, Deniz Anuk; Gökdemir, Mahmut; Tekindal, M. Agah; Gülcan, Hande; Tarcan, Aylin
2014-01-01
Background: Inferior vena cava (IVC) oxygen saturation as an indicator of mixed venous oxygenation may be valuable for understanding postnatal adaptations in newborn infants. It is unknown how this parameter progresses in critically ill premature infants. Aims: To investigate IVC oxygen saturation during the first three days of life in preterm infants with and without patent ductus arteriosus (PDA). Study Design: Case-control study. Methods: Twenty-seven preterm infants were admitted to the Neonatal Intensive Care. Preterm infants with umbilical venous catheterization were included in the study. Six umbilical venous blood gas values were obtained from each infant during the first 72 hours of life. Preterm infants in the study were divided into two groups. Haemodynamically significant PDA was diagnosed by echocardiography in 11 (41%) infants before the 72nd hour of life in the study group and ibuprofen treatment was started, whereas 16 (59%) infants who didn’t have haemodynamically significant PDA were included in the control group. Results: In the entire group, the highest value of mean IVC oxygen saturation was 79.9% at the first measurement and the lowest was 64.8% at the 72nd hour. Inferior vena cava oxygen saturations were significantly different between the study and control groups. Post-hoc analysis revealed that the first and 36th hour measurements made the difference (p=0.01). Conclusion: Inferior vena cava oxygen saturation was found to be significantly different between preterm infants with and without PDA. Further studies are needed to understand the effect of foetal shunts on venous oxygenation during postnatal adaptation in newborn infants. PMID:25337418
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2013-10-01
demonstrated that NIRS measurement of hemoglobin oxygen saturation in the tibial compartment provided reliable and sensitive correlation to increases...on 60 healthy participants. Our results indicated that NIRS was able to detect changes in oxygen saturation of muscle with exercise in all 60...Model 41 Introduction 42 Over the last two decades, tissue oxygenation saturation (StO2) measured by near infrared 43 spectroscopy (NIRS) has
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Simulation of hydrodynamics, temperature, and dissolved oxygen in Beaver Lake, Arkansas, 1994-1995
Haggard, Brian; Green, W. Reed
2002-01-01
The tailwaters of Beaver Lake and other White River reservoirs support a cold-water trout fishery of significant economic yield in northwestern Arkansas. The Arkansas Game and Fish Commission has requested an increase in existing minimum flows through the Beaver Lake dam to increase the amount of fishable waters downstream. Information is needed to assess the impact of additional minimum flows on temperature and dissolved-oxygen qualities of reservoir water above the dam and the release water. A two-dimensional, laterally averaged hydrodynamic, thermal and dissolved-oxygen model was developed and calibrated for Beaver Lake, Arkansas. The model simulates surface-water elevation, currents, heat transport and dissolved-oxygen dynamics. The model was developed to assess the impacts of proposed increases in minimum flows from 1.76 cubic meters per second (the existing minimum flow) to 3.85 cubic meters per second (the additional minimum flow). Simulations included assessing (1) the impact of additional minimum flows on tailwater temperature and dissolved-oxygen quality and (2) increasing initial water-surface elevation 0.5 meter and assessing the impact of additional minimum flow on tailwater temperatures and dissolved-oxygen concentrations. The additional minimum flow simulation (without increasing initial pool elevation) appeared to increase the water temperature (<0.9 degrees Celsius) and decrease dissolved oxygen concentration (<2.2 milligrams per liter) in the outflow discharge. Conversely, the additional minimum flow plus initial increase in pool elevation (0.5 meter) simulation appeared to decrease outflow water temperature (0.5 degrees Celsius) and increase dissolved oxygen concentration (<1.2 milligrams per liter) through time. However, results from both minimum flow scenarios for both water temperature and dissolved oxygen concentration were within the boundaries or similar to the error between measured and simulated water column profile values.
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Intramyocardial oxygen transport by quantitative diffuse reflectance spectroscopy in calves
NASA Astrophysics Data System (ADS)
Lindbergh, Tobias; Larsson, Marcus; Szabó, Zoltán; Casimir-Ahn, Henrik; Strömberg, Tomas
2010-03-01
Intramyocardial oxygen transport was assessed during open-chest surgery in calves by diffuse reflectance spectroscopy using a small intramuscular fiber-optic probe. The sum of hemo- and myoglobin tissue fraction and oxygen saturation, the tissue fraction and oxidation of cytochrome aa3, and the tissue fraction of methemoglobin were estimated using a calibrated empirical light transport model. Increasing the oxygen content in the inhaled gas, 21%-50%-100%, in five calves (group A) gave an increasing oxygen saturation of 19+/-4%, 24+/-5%, and 28+/-8% (p<0.001, ANOVA repeated measures design) and mean tissue fractions of 1.6% (cytochrome aa3) and 1.1% (hemo- and myoglobin). Cardiac arrest in two calves gave an oxygen saturation lower than 5%. In two calves (group B), a left ventricular assistive device (LVAD pump) was implanted. Oxygen saturation in group B animals increased with LVAD pump speed (p<0.001, ANOVA) and with oxygen content in inhaled gas (p<0.001, ANOVA). The cytochrome aa3 oxidation level was above 96% in both group A and group B calves, including the two cases involving cardiac arrest. In conclusion, the estimated tissue fractions and oxygenation/oxidation levels of the myocardial chromophores during respiratory and hemodynamic provocations were in agreement with previously presented results, demonstrating the potential of the method.
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The role of the oceanic oxygen minima in generating biodiversity in the deep sea
NASA Astrophysics Data System (ADS)
Rogers, Alex D.
2000-01-01
Many studies on the deep-sea benthic biota have shown that the most species-rich areas lie on the continental margins between 500 and 2500 m, which coincides with the present oxygen-minimum in the world's oceans. Some species have adapted to hypoxic conditions in oxygen-minimum zones, and some can even fulfil all their energy requirements through anaerobic metabolism for at least short periods of time. It is, however, apparent that the geographic and vertical distribution of many species is restricted by the presence of oxygen-minimum zones. Historically, cycles of global warming and cooling have led to periods of expansion and contraction of oxygen-minimum layers throughout the world's oceans. Such shifts in the global distribution of oxygen-minimum zones have presented many opportunities for allopatric speciation in organisms inhabiting slope habitats associated with continental margins, oceanic islands and seamounts. On a smaller scale, oxygen-minimum zones can be seen today as providing a barrier to gene-flow between allopatric populations. Recent studies of the Arabian Sea and in other regions of upwelling also have shown that the presence of an oxygen-minimum layer creates a strong vertical gradient in physical and biological parameters. The reduced utilisation of the downward flux of organic material in the oxygen-minimum zone results in an abundant supply of food for organisms immediately below it. The occupation of this area by species exploiting abundant food supplies may lead to strong vertical gradients in selective pressures for optimal rates of growth, modes of reproduction and development and in other aspects of species biology. The presence of such strong selective gradients may have led to an increase in habitat specialisation in the lower reaches of oxygen-minimum zones and an increased rate of speciation.
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Kussman, Barry D; Wypij, David; Laussen, Peter C; Soul, Janet S; Bellinger, David C; DiNardo, James A; Robertson, Richard; Pigula, Frank A; Jonas, Richard A; Newburger, Jane W
2010-07-20
Near-infrared spectroscopy monitoring of cerebral oxygen saturation (rSo(2)) has become routine in many centers, but no studies have reported the relationship of intraoperative near-infrared spectroscopy to long-term neurodevelopmental outcomes after cardiac surgery. Of 104 infants undergoing biventricular repair without aortic arch reconstruction, 89 (86%) returned for neurodevelopmental testing at 1 year of age. The primary near-infrared spectroscopy variable was the integrated rSo(2) (area under the curve) for rSo(2)
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Derin, S; Altun, I; Koseoglu, S; Sahin, C; Yilmaz, M; Akin, F; Sahan, M
2018-05-01
This study aimed to investigate the relationship of epicardial fat thickness with severity of obstructive sleep apnoea, and clinical and polysomnographic parameters, and to determine independent predictors for epicardial fat thickness. A total of 84 patients with a body mass index of less than 30 kg/m2 and suspected sleep-disordered breathing were included in the study. The correlations of epicardial fat thickness with polysomnographic and clinical data, and severity of obstructive sleep apnoea, were investigated. Mean epicardial fat thickness was 3.75 ± 1.07 mm in the study group (n = 62) and 2.97 ± 0.62 mm in the control group (n = 22) (p < 0.001). There were significant positive correlations between epicardial fat thickness and: apnoea/hypopnoea index, oxygen desaturation index 3 and minimum oxygen saturation, as well as with age, body mass index, and neck and waist circumferences. Non-obese obstructive sleep apnoea patients have thicker epicardial fat compared to controls. Oxygen desaturation index 3 has a strong correlation with epicardial fat thickness and is an independent predictor of it.
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Hu, Zhiyong; Xu, Lili; Zhu, Zhirui; Seal, Robert; McQuillan, Patrick M.
2016-01-01
Abstract The objective of this study was to evaluate the effect of hypothermic cardiopulmonary bypass (CPB) on cerebral oxygen saturation (rSO2), internal jugular bulb venous oxygen saturation (SjvO2), mixed venous oxygen saturation (SvO2), and bispectral index (BIS) used to monitor cerebral oxygen balance in pediatric patients. Sixty American Society of Anesthesiologists Class II-III patients aged 1 to 4 years old with congenital heart disease scheduled for elective cardiac surgery were included in this study. Temperature, BIS, rSO2, mean arterial pressure, central venous pressure, cerebral perfusion pressure (CPP), and hematocrit were recorded. Internal jugular bulb venous oxygen saturation and SvO2 were obtained from blood gas analysis at the time points: after induction of anesthesia (T0), beginning of CPB (T1), ascending aortic occlusion (T2), 20 minutes after initiating CPB (T3), coronary reperfusion (T4), separation from CPB (T5), and at the end of operation (T6). The effect of hypothermia or changes in CPP on rSO2, SjvO2, SvO2, and BIS were analyzed. Compared with postinduction baseline values, rSO2 significantly decreased at all-time points: onset of extracorporeal circulation, ascending aortic occlusion, 20 minutes after CPB initiation, coronary reperfusion, and separation from CPB (P < 0.05). Compared with measurements made following induction of anesthesia, SjvO2 significantly increased with initiation of CPB, ascending aortic occlusion, 20 minutes after initiating CPB, coronary reperfusion, and separation from CPB (P < 0.05). Compared with induction of anesthesia, BIS significantly decreased with the onset of CPB, aortic cross clamping, 20 minutes after initiating CPB, and coronary reperfusion (P < 0.05). Bispectral index increased following separation from CPB. There was no significant change in SvO2 during cardiopulmonary bypass (P > 0.05). Correlation analysis demonstrated that rSO2 was positively related to CPP (r = 0.687, P = 0.000), with a low linear correlation to temperature (r = 0.453, P = 0.000). Internal jugular bulb venous oxygen saturation was negatively related to temperature (r = −0.689, P = 0.000). Bispectral index was positively related to both temperature (r = 0.824, P = 0.000) and CPP (r = 0.782, P = 0.000). Cerebral oxygen saturation had a positive linear correlation with CPP and a low linear correlation to temperature. Internal jugular bulb venous oxygen saturation had a negative linear correlation to temperature. Pre-and and early postbypass periods are vulnerable times for adequate cerebral oxygenation. Anesthetic management must aim to optimize the supply and demand relationship. PMID:26765454
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Hu, Zhiyong; Xu, Lili; Zhu, Zhirui; Seal, Robert; McQuillan, Patrick M
2016-01-01
The objective of this study was to evaluate the effect of hypothermic cardiopulmonary bypass (CPB) on cerebral oxygen saturation (rSO2), internal jugular bulb venous oxygen saturation (SjvO2), mixed venous oxygen saturation (SvO2), and bispectral index (BIS) used to monitor cerebral oxygen balance in pediatric patients.Sixty American Society of Anesthesiologists Class II-III patients aged 1 to 4 years old with congenital heart disease scheduled for elective cardiac surgery were included in this study. Temperature, BIS, rSO2, mean arterial pressure, central venous pressure, cerebral perfusion pressure (CPP), and hematocrit were recorded. Internal jugular bulb venous oxygen saturation and SvO2 were obtained from blood gas analysis at the time points: after induction of anesthesia (T0), beginning of CPB (T1), ascending aortic occlusion (T2), 20 minutes after initiating CPB (T3), coronary reperfusion (T4), separation from CPB (T5), and at the end of operation (T6). The effect of hypothermia or changes in CPP on rSO2, SjvO2, SvO2, and BIS were analyzed.Compared with postinduction baseline values, rSO2 significantly decreased at all-time points: onset of extracorporeal circulation, ascending aortic occlusion, 20 minutes after CPB initiation, coronary reperfusion, and separation from CPB (P < 0.05). Compared with measurements made following induction of anesthesia, SjvO2 significantly increased with initiation of CPB, ascending aortic occlusion, 20 minutes after initiating CPB, coronary reperfusion, and separation from CPB (P < 0.05). Compared with induction of anesthesia, BIS significantly decreased with the onset of CPB, aortic cross clamping, 20 minutes after initiating CPB, and coronary reperfusion (P < 0.05). Bispectral index increased following separation from CPB. There was no significant change in SvO2 during cardiopulmonary bypass (P > 0.05). Correlation analysis demonstrated that rSO2 was positively related to CPP (r = 0.687, P = 0.000), with a low linear correlation to temperature (r = 0.453, P = 0.000). Internal jugular bulb venous oxygen saturation was negatively related to temperature (r = -0.689, P = 0.000). Bispectral index was positively related to both temperature (r = 0.824, P = 0.000) and CPP (r = 0.782, P = 0.000). Cerebral oxygen saturation had a positive linear correlation with CPP and a low linear correlation to temperature. Internal jugular bulb venous oxygen saturation had a negative linear correlation to temperature.Pre-and and early postbypass periods are vulnerable times for adequate cerebral oxygenation. Anesthetic management must aim to optimize the supply and demand relationship.
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Delazer, Margarete; Zamarian, Laura; Frauscher, Birgit; Mitterling, Thomas; Stefani, Ambra; Heidbreder, Anna; Högl, Birgit
2016-08-01
This study assessed decision-making and its associations with executive functions and sleep-related factors in patients with obstructive sleep apnea. Thirty patients with untreated obstructive sleep apnea and 20 healthy age- and education-matched controls performed the Iowa Gambling Task, a decision-making task under initial ambiguity, as well as an extensive neuropsychological test battery. Patients, but not controls, also underwent a detailed polysomnographic assessment. Results of group analyses showed that patients performed at the same level of controls on the Iowa Gambling Task. However, the proportion of risky performers was significantly higher in the patient group than in the control group. Decision-making did not correlate with executive functions and subjective ratings of sleepiness, whereas there was a significant positive correlation between advantageous performance on the Iowa Gambling Task and percentage of N2 sleep, minimal oxygen saturation, average oxygen saturation and time spent below 90% oxygen saturation level. Also, the minimal oxygen saturation accounted for 27% of variance in decision-making. In conclusion, this study shows that a subgroup of patients with obstructive sleep apnea may be at risk of disadvantageous decision-making under ambiguity. Among the sleep-related factors, oxygen saturation is a significant predictor of advantageous decision-making. © 2016 European Sleep Research Society.
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NASA Astrophysics Data System (ADS)
Sato, K.; Jung, J. Y.; Levin, L. A.
2016-02-01
The rapid pace of deoxygenation and ocean acidification associated with anthropogenic climate change on upwelling margins will have differing effects on marine species from the population level down to the nanoscale. Driven by the understudied effects of climate change in the deep sea, we address the question, how will dominant echinoid urchins respond to future changes in multiple stressors (i.e. ocean acidification, deoxygenation, and shoaling of hypoxic water and calcium carbonate saturation horizons) on the southern California continental slope? Samples of the sea urchin, Strongylocentrotus fragilis, were collected along gradients of multiple hydrographic variables and analyzed for phenotypic variation with respect to multiple climate change stressors (oxygen, pH, and temperature). We compare fitness traits of S. fragilis collected along the continental slope and through the Oxygen Minimum Zone (OMZ), which include growth rate, morphology, and reproductive output, in addition to nanoscale structural and biomechanical test properties. Our results indicate that growth rate of S. fragilis is directly correlated with dissolved oxygen and pH, but not depth or temperature. Reproductive output, as measured by a standard gonad index, was found to be sensitive at the OMZ core (pH 7.40; O2 0.25 mL/L), which suggests a nonlinear response to chemical stressors. Preliminary analysis of mineral density in test pieces imaged using micro- and nano- computed tomography indicates exposure to conditions in the OMZ reduces calcification. This improved understanding of how continental margin urchins differ along natural physicochemical gradients will provide modern-day insight into the threshold tolerances of species to multiple stressors and will help guide future manipulation experiments as well as fisheries and spatial management.
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Ammonium and nitrite oxidation at nanomolar oxygen concentrations in oxygen minimum zone waters
Bristow, Laura A.; Dalsgaard, Tage; Tiano, Laura; Mills, Daniel B.; Bertagnolli, Anthony D.; Wright, Jody J.; Hallam, Steven J.; Ulloa, Osvaldo; Canfield, Donald E.; Revsbech, Niels Peter; Thamdrup, Bo
2016-01-01
A major percentage of fixed nitrogen (N) loss in the oceans occurs within nitrite-rich oxygen minimum zones (OMZs) via denitrification and anammox. It remains unclear to what extent ammonium and nitrite oxidation co-occur, either supplying or competing for substrates involved in nitrogen loss in the OMZ core. Assessment of the oxygen (O2) sensitivity of these processes down to the O2 concentrations present in the OMZ core (<10 nmol⋅L−1) is therefore essential for understanding and modeling nitrogen loss in OMZs. We determined rates of ammonium and nitrite oxidation in the seasonal OMZ off Concepcion, Chile at manipulated O2 levels between 5 nmol⋅L−1 and 20 μmol⋅L−1. Rates of both processes were detectable in the low nanomolar range (5–33 nmol⋅L−1 O2), but demonstrated a strong dependence on O2 concentrations with apparent half-saturation constants (Kms) of 333 ± 130 nmol⋅L−1 O2 for ammonium oxidation and 778 ± 168 nmol⋅L−1 O2 for nitrite oxidation assuming one-component Michaelis–Menten kinetics. Nitrite oxidation rates, however, were better described with a two-component Michaelis–Menten model, indicating a high-affinity component with a Km of just a few nanomolar. As the communities of ammonium and nitrite oxidizers were similar to other OMZs, these kinetics should apply across OMZ systems. The high O2 affinities imply that ammonium and nitrite oxidation can occur within the OMZ core whenever O2 is supplied, for example, by episodic intrusions. These processes therefore compete with anammox and denitrification for ammonium and nitrite, thereby exerting an important control over nitrogen loss. PMID:27601665
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Nemer, Sérgio Nogueira; Caldeira, Jefferson B; Santos, Ricardo G; Guimarães, Bruno L; Garcia, João Márcio; Prado, Darwin; Silva, Ricardo T; Azeredo, Leandro M; Faria, Eduardo R; Souza, Paulo Cesar P
2015-12-01
To verify whether high positive end-expiratory pressure levels can increase brain tissue oxygen pressure, and also their effects on pulse oxygen saturation, intracranial pressure, and cerebral perfusion pressure. Twenty traumatic brain injury patients with acute respiratory distress syndrome were submitted to positive end-expiratory pressure levels of 5, 10, and 15 cm H2O progressively. The 3 positive end-expiratory pressure levels were used during 20 minutes for each one, whereas brain tissue oxygen pressure, oxygen saturation, intracranial pressure, and cerebral perfusion pressure were recorded. Brain tissue oxygen pressure and oxygen saturation increased significantly with increasing positive end-expiratory pressure from 5 to 10 and from 10 to 15 cm H2O (P=.0001 and P=.0001 respectively). Intracranial pressure and cerebral perfusion pressure did not differ significantly with increasing positive end-expiratory pressure from 5 to 10 and from 10 to 15 cm H2O (P=.16 and P=.79 respectively). High positive end-expiratory pressure levels increased brain tissue oxygen pressure and oxygen saturation, without increase in intracranial pressure or decrease in cerebral perfusion pressure. High positive end-expiratory pressure levels can be used in severe traumatic brain injury patients with acute respiratory distress syndrome as a safe alternative to improve brain oxygenation. Copyright © 2015 Elsevier Inc. All rights reserved.
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Safety, reliability, and validity of a physiologic definition of bronchopulmonary dysplasia.
Walsh, Michele C; Wilson-Costello, Deanna; Zadell, Arlene; Newman, Nancy; Fanaroff, Avroy
2003-09-01
Bronchopulmonary dysplasia (BPD) is the focus of many intervention trials, yet the outcome measure when based solely on oxygen administration may be confounded by differing criteria for oxygen administration between physicians. Thus, we wished to define BPD by a standardized oxygen saturation monitoring at 36 weeks corrected age, and compare this physiologic definition with the standard clinical definition of BPD based solely on oxygen administration. A total of 199 consecutive very low birthweight infants (VLBW, 501 to 1500 g birthweight) were assessed prospectively at 36+/-1 weeks corrected age. Neonates on positive pressure support or receiving >30% supplemental oxygen were assigned the outcome BPD. Those receiving < or =30% oxygen underwent a stepwise 2% reduction in supplemental oxygen to room air while under continuous observation and oxygen saturation monitoring. Outcomes of the test were "no BPD" (saturations > or =88% for 60 minutes) or "BPD" (saturation < 88%). At the conclusion of the test, all infants were returned to their baseline oxygen. Safety (apnea, bradycardia, increased oxygen use), inter-rater reliability, test-retest reliability, and validity of the physiologic definition vs the clinical definition were assessed. A total of 199 VLBW were assessed, of whom 45 (36%) were diagnosed with BPD by the clinical definition of oxygen use at 36 weeks corrected age. The physiologic definition identified 15 infants treated with oxygen who successfully passed the saturation monitoring test in room air. The physiologic definition diagnosed BPD in 30 (24%) of the cohort. All infants were safely studied. The test was highly reliable (inter-rater reliability, kappa=1.0; test-retest reliability, kappa=0.83) and highly correlated with discharge home in oxygen, length of hospital stay, and hospital readmissions in the first year of life. The physiologic definition of BPD is safe, feasible, reliable, and valid and improves the precision of the diagnosis of BPD. This may be of benefit in future multicenter clinical trials.
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Chance, Britton; Ma, Hong Yan; Nioka, Shoko
2003-01-01
The quantification of tissue oxygen by frequency or time domain methods has been discussed in a number of prior publications where the meaning of the tissue hemoglobin oxygen saturation was unclear and where the CW instruments were unsuitable for proper quantitative measurements [1, 2]. The development of the IQ Phase Meter has greatly simplified and made reliable the difficult determination of precise phase and amplitude signals from brain. This contribution reports on the calibration of the instrument in model systems and the use of the instrument to measure tissue saturation (StO2) in a small animal model. In addition, a global interpretation of the meaning of tissue oxygen has been formulated based on the idea that autoregulation will maintain tissue oxygen at a fixed value over a range of arterial and venous oxygen values over the range of autoregulation. Beyond that range, the tissue oxygen is still correctly measured but, as expected, approaches the arterial saturation at low metabolic rates and the venous saturation at high metabolic rates of mitochondria.
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Safe-to-Fly Testing of the Guardian Angel Integrated Oxygen System (GAIOS)
2013-07-01
times during the testing the participant’s blood oxygen saturation percentage was measured by a fingertip pulse oximeter . During the DMOS and...the oxygen flowing to both masks was measured. Several times during the testing the participants’ blood oxygen saturation percentage was measured...by a fingertip pulse oximeter . During the MMOS testing with a ventilator a pararescueman operated the ventilator and breathed from the chamber
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Blood oxygen saturation determined by transmission spectrophotometry of hemolyzed blood samples
NASA Technical Reports Server (NTRS)
Malik, W. M.
1967-01-01
Use of the Lambert-Beer Transmission Law determines blood oxygen saturation of hemolyzed blood samples. This simplified method is based on the difference in optical absorption properties of hemoglobin and oxyhemoglobin.
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2013-03-14
Dexamethasone increased maximal aerobic capacity compared with placebo. For example, pulse oximeter oxygen saturation at rest was significantly lower...IHE for 6 to 7 days reduces AMS by an estimated 20% and increases oxygen saturation levels by 1% to 3%. Several IHE protocols exist, but none have... oxygen kinetics (pɘ.05) and reduced ventilator equivalent for CO2 (pɘ.01); no significant difference in peak O2 saturation between groups
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Maitland, Kathryn; Kiguli, Sarah; Opoka, Robert O.; Olupot-Olupot, Peter; Engoru, Charles; Njuguna, Patricia; Bandika, Victor; Mpoya, Ayub; Bush, Andrew; Williams, Thomas N.; Grieve, Richard; Sadique, Zia; Fraser, John; Harrison, David; Rowan, Kathy
2018-01-01
Background: In Africa, the clinical syndrome of pneumonia remains the leading cause of morbidity and mortality in children in the post-neonatal period. This represents a significant burden on in-patient services. The targeted use of oxygen and simple, non-invasive methods of respiratory support may be a highly cost-effective means of improving outcome, but the optimal oxygen saturation threshold that results in benefit and the best strategy for delivery are yet to be tested in adequately powered randomised controlled trials. There is, however, an accumulating literature about the harms of oxygen therapy across a range of acute and emergency situations that have stimulated a number of trials investigating permissive hypoxia. Methods: In 4200 African children, aged 2 months to 12 years, presenting to 5 hospitals in East Africa with respiratory distress and hypoxia (oxygen saturation < 92%), the COAST trial will simultaneously evaluate two related interventions (targeted use of oxygen with respect to the optimal oxygen saturation threshold for treatment and mode of delivery) to reduce shorter-term mortality at 48-hours (primary endpoint), and longer-term morbidity and mortality to 28 days in a fractional factorial design, that compares: Liberal oxygenation (recommended care) compared with a strategy that permits hypoxia to SpO 2 > or = 80% (permissive hypoxia); andHigh flow using AIrVO 2 TM compared with low flow delivery (routine care). Discussion: The overarching objective is to address the key research gaps in the therapeutic use of oxygen in resource-limited setting in order to provide a better evidence base for future management guidelines. The trial has been designed to address the poor outcomes of children in sub-Saharan Africa, which are associated with high rates of in-hospital mortality, 9-10% (for those with oxygen saturations of 80-92%) and 26-30% case fatality for those with oxygen saturations <80%. Clinical trial registration: ISRCTN15622505 Trial status: Recruiting PMID:29383331
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Zhao, Shun-yun; Wu, Xin-min; Guo, Ya-min; Zhang, Shu-shun; An, Yan-ming; Li, Bing; Wang, Hao
2013-06-11
To explore the blood oxygen saturation and heart rate changes of the Antarctic explorers. During August 2010 to April 2011, the changes in blood oxygen saturation, heart rate and plateau reaction of 16 Antarctic expedition team in different plateau environments (Tibetan plateau versus Antarctic plateau) were monitored with the noninvasive pulse oximeter MD300-C. The extent of acute mountain sickness was determined according to the Lake Louise Consensus acute mountain reaction symptom scores and judgment method. The changes of blood oxygen saturation, heart rate at different altitudes of 110, 3650, 4300 m (96.8% ± 1.2%,89.1% ± 1.2%, 86.1% ± 2.0%, (75.0 ± 5.4) times/min, (104.0 ± 4.3) times/min, (113.0 ± 5.2) times/min,F = 214.155, 240.088,both P < 0.05). With rising latitude and elevation gradient in Antarctic plateau, the changes of blood oxygen saturation, heart rate at different altitudes of 2000, 2500, 3000, 3500 and 4087 m(91.9% ± 1.3%,90.5% ± 1.3%,87.6% ± 1.4%,85.0% ± 1.8%,81.5% ± 2.2%, (85.9 ± 3.2) times/min, (90.6 ± 2.8) times/min, (97.8 ± 4.1) times/min, (102.0 ± 3.4) times/min, (106.3 ± 3.9) times/min, F = 105.418, 90.174, both P < 0.05). Levels of blood oxygen saturation and heart rate were both correlated with the risk of altitude sickness (r = -0.446 and 0.565, both P < 0.05). As the increases of altitude, there are significant changes in oxygen saturation, heart rate of the Antarctic explorers. And with the increases of altitude, the risk of altitude sickness gradually increases.
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Birang, Reza; Kaviani, Naser; Mohammadpour, Mehdi; Abed, Ahmad Moghareh; Gutknecht, Norbert; Mir, Maziar
2008-07-01
Dentine hypersensitivity has of long been known to be a common clinical problem in dental practices. Lasers have recently come to play a prominent role in the treatment of this disorder. They might, however, cause dental pulp damage. This study was conducted to evaluate the effect of Nd:yttrium-aluminum-garnet (YAG) laser on partial oxygen saturation of pulpal blood in sensitive anterior teeth. In this clinical trial, 65 hypersensitive teeth were selected and randomly allocated to two groups. The study group involved Nd:YAG laser treatment, while no treatment was employed for the control group. Using a pulse oximetry system, evaluations were preformed of the partial oxygen saturation in the pulpal blood before, immediately after, 1 week after, and 1 month after the treatment. The results were analyzed using the SPSS software and repeated-measures analysis of variance and paired-samples t tests. The mean partial oxygen saturation of the blood was found to be 85.4% in the study group, which was not significantly different from that of the control group. No significant differences were observed in the control group between the means obtained from pretreatment and post-treatment intervals (P > 0.05). The Post-treatment partial oxygen saturation mean rose to 89.3% (P = 0.001) and remained constant throughout the following week after it. However, no significant differences were found between the pretreatment partial oxygen saturation mean and the same measurement 1 month after treatment (P = 0.702). Nd:YAG laser therapy for dentine desensitization of anterior teeth caused no persistent changes in the partial oxygen saturation of pulpal blood. It may, therefore, be concluded that the diffusion of heat induced by the Nd:YAG laser into the pulp within the limit of the desensitization parameters cause no irreversible damages in the dental pulp.
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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
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[Effect of simulated microgravity on peripheral oxygen saturation in rats].
Chen, Guangfei; Zhang, Yahui; Yuan, Ming; He, Shilin; Ying, Jun; Li, Chen
2018-02-01
To study the effect of microgravity on peripheral oxygen saturation (SpO 2 ) in rats, tail-suspended rats were applied to simulate microgravity environment. SpO 2 and arterial oxygen saturation (SaO 2 ) were measured by pulse oximeter and arterial blood gas analyzer (ABGA) respectively on the 14th day, 21st day and 28th day in tail-suspended group and control group. Paired t -test shows that SpO 2 was significantly lower than SaO 2 in tail-suspended group on the 14th day ( P < 0.05), the 21st day ( P < 0.05) and the 28th day ( P < 0.01). The ANOVA results shows that modeling time had significant effect on SpO 2 value but no effect on SaO 2 value in tail-suspended group. These results indicate that pulse oximeter may be not suitable for oxygen saturation test in microgravity environment.
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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.
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Quantitative evaluation of ViOptix's tissue oximeter in an ex-vivo animal model
NASA Astrophysics Data System (ADS)
Mao, Jimmy J. M.; Xu, Ronald; Lash, Bob; Wright, Leigh
2008-02-01
We evaluate the performance of ODISsey TM Tissue Oximeter (ViOptix, Inc., Fremont, CA) against co-oximeter. Concurrent oxygen saturation measurements were made in three dog limbs surgically removed and perfused with an extracorporeal blood circulation system. Oxygen saturation was adjusted in steps ranging from 95% down to 5% as monitored by the co-oximeter. The co-oximeter was used to measure the oxygen saturation of the whole blood drawn from both the arterial and the venous ports of the limb. The tissue oxygenation measured by the ODISsey TM tissue oximeter was compared with the average of the arterial and the venous blood oxygenation measured by the co-oximeter. Linear correlation was observed between the average oxygenation given by the co-oximeter and the ODISseyTM readings, with a root-mean-square difference of 7.6% and the correlation coefficient of 0.941, calculated from N = 194 data points.
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O, Odette; Churgin, Sarah M; Sladky, Kurt K; Smith, Lesley J
2015-09-01
Inland bearded dragons (Pogona vitticeps, n=6) were anesthetized for 1 hr using isoflurane in either 100% oxygen or 21% oxygen (FI 21; medical-grade room air). Parameters of anesthetic depth were recorded throughout both induction and recovery by an observer blinded to the fraction of inspired oxygen (FiO2), including the loss and return of withdrawal and righting reflexes, muscle tone, ability to intubate or extubate, and return to spontaneous respiration. Physiologic data were recorded every 5 min throughout the anesthetic procedures, including heart rate, body temperature, end-tidal CO2, hemoglobin oxygen saturation (SpO2), and percent expired isoflurane. Lizards were subjected to application of a noxious stimulus (needle stick) at 0, 30, and 60 min, and responses recorded. Following a minimum 7-day washout period, the experiment was repeated with each lizard subjected to the other protocol in a randomized, complete crossover design. The only statistically significant difference was a lower mean SpO2 in the group inspiring 21% oxygen (P<0.0020). No statistically significant differences were detected in any parameters during induction or recovery; however, all values were uniformly shorter for the FI 21 group, indicating a possible clinically significant difference. A larger sample size may have detected statistically significant differences. Further studies are needed to evaluate these effects in other reptile species and with the concurrent use of injectable anesthetic and analgesic drugs.
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Accuracy of peripheral arterial tonometry in the diagnosis of obstructive sleep apnea.
Pinto, José Antonio; Godoy, Luciana Balester Mello de; Ribeiro, Renata Coutinho; Mizoguchi, Elcio Izumi; Hirsch, Lina Ana Medeiros; Gomes, Leonardo Marques
2015-01-01
The use of handheld devices that assess peripheral arterial tonometry has emerged as an auxiliary method for assessment and diagnosis of obstructive sleep apnea syndrome. To evaluate the accuracy of peripheral arterial tonometry in the diagnosis of obstructive sleep apnea. Contemporary cohort cross-sectional study. Thirty patients with suspected obstructive sleep apnea underwent peripheral arterial tonometry and assisted nocturnal polysomnography concomitantly. The mean apnea/hypopnea index by peripheral arterial tonometry was significantly higher than that by polysomnography (p<0.001), but the values of both sleep studies were significantly correlated (r=0.762). There was a high correlation between variables: minimum oxygen saturation (r=0.842, p<0.001), oxygen saturation<90% (r=0.799, p<0.001), and mean heart rate (r=0.951, p<0.001). Sensitivity and specificity were 60% and 96.2% (AUC: 0.727; p=0.113), respectively, when at a threshold value of 5 events/h. In severe cases (≥30 events/h), the result was a sensitivity of 77.8% and a specificity of 86.4% (AUC: 0.846, p=0.003). Peripheral arterial tonometry is a useful portable device for the diagnosis of obstructive sleep apnea; its accuracy is higher in moderate and severe cases. Copyright © 2015 Associação Brasileira de Otorrinolaringologia e Cirurgia Cérvico-Facial. Published by Elsevier Editora Ltda. All rights reserved.
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Comparison of Minimally and More Invasive Methods of Determining Mixed Venous Oxygen Saturation.
Smit, Marli; Levin, Andrew I; Coetzee, Johan F
2016-04-01
To investigate the accuracy of a minimally invasive, 2-step, lookup method for determining mixed venous oxygen saturation compared with conventional techniques. Single-center, prospective, nonrandomized, pilot study. Tertiary care hospital, university setting. Thirteen elective cardiac and vascular surgery patients. All participants received intra-arterial and pulmonary artery catheters. Minimally invasive oxygen consumption and cardiac output were measured using a metabolic module and lithium-calibrated arterial waveform analysis (LiDCO; LiDCO, London), respectively. For the minimally invasive method, Step 1 involved these minimally invasive measurements, and arterial oxygen content was entered into the Fick equation to calculate mixed venous oxygen content. Step 2 used an oxyhemoglobin curve spreadsheet to look up mixed venous oxygen saturation from the calculated mixed venous oxygen content. The conventional "invasive" technique used pulmonary artery intermittent thermodilution cardiac output, direct sampling of mixed venous and arterial blood, and the "reverse-Fick" method of calculating oxygen consumption. LiDCO overestimated thermodilution cardiac output by 26%. Pulmonary artery catheter-derived oxygen consumption underestimated metabolic module measurements by 27%. Mixed venous oxygen saturation differed between techniques; the calculated values underestimated the direct measurements by between 12% to 26.3%, this difference being statistically significant. The magnitude of the differences between the minimally invasive and invasive techniques was too great for the former to act as a surrogate of the latter and could adversely affect clinical decision making. Copyright © 2016 Elsevier Inc. All rights reserved.
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Keilani, C; Halalchi, A; Wakpi Djeugue, D; Regis, A; Abada, S
2016-12-01
In the present study, we examined retinal vascular oxygen saturation in patients with retinal vein occlusion (RVO), high blood pressure (HBP) and dyslipidemia, before and during intravitreal vascular endothelial growth factor (VEGF) injection (ranibizumab). We retrospectively reviewed the medical records of six patients with visual acuity (VA) reduced by macular edema (ME) secondary to RVO with HBP and dyslipidemia, who underwent intravitreal anti-VEGF injection between October 2014 and February 2015 in the department of ophthalmology of François-Quesnay Hospital at Mantes-la-Jolie (France). The main inclusion criterion was the presence of RVO with ME and decreased VA. The primary endpoint was improvement of retinal venous oxygen saturation in patients with RVO before and 3 months after intravitreal ranibizumab injection. Secondary outcomes were improvement of retinal arterial oxygen saturation, improvement of best-corrected visual acuity (BCVA) on the Early Treatment Diabetic Retinopathy Study (ETDRS) scale, regression of ME measured by the central macular thickness (CMT) in nm and studying the correlation between blood pressure (BP) and retinal venous oxygen saturation before and after ranibizumab. Six eyes of six patients were included. Before treatment, the mean (standard deviation [SD]) of the retinal venous saturation (%) was 38.1±14.2. Three months after the injections, the mean (SD) of the retinal venous saturation (%) increased statistically significantly 49.2±11 (P=0.03). In this study, retinal venous oxygen saturation in patients with RVO, HBP and dyslipidemia was partially normalized during intravitreal ranibizumab treatment. Copyright © 2016 Elsevier Masson SAS. All rights reserved.
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Microbialites and global environmental change across the Permian-Triassic boundary: a synthesis.
Kershaw, S; Crasquin, S; Li, Y; Collin, P-Y; Forel, M-B; Mu, X; Baud, A; Wang, Y; Xie, S; Maurer, F; Guo, L
2012-01-01
Permian-Triassic boundary microbialites (PTBMs) are thin (0.05-15 m) carbonates formed after the end-Permian mass extinction. They comprise Renalcis-group calcimicrobes, microbially mediated micrite, presumed inorganic micrite, calcite cement (some may be microbially influenced) and shelly faunas. PTBMs are abundant in low-latitude shallow-marine carbonate shelves in central Tethyan continents but are rare in higher latitudes, likely inhibited by clastic supply on Pangaea margins. PTBMs occupied broadly similar environments to Late Permian reefs in Tethys, but extended into deeper waters. Late Permian reefs are also rich in microbes (and cements), so post-extinction seawater carbonate saturation was likely similar to the Late Permian. However, PTBMs lack widespread abundant inorganic carbonate cement fans, so a previous interpretation that anoxic bicarbonate-rich water upwelled to rapidly increase carbonate saturation of shallow seawater, post-extinction, is problematic. Preliminary pyrite framboid evidence shows anoxia in PTBM facies, but interbedded shelly faunas indicate oxygenated water, perhaps there was short-term pulsing of normally saturated anoxic water from the oxygen-minimum zone to surface waters. In Tethys, PTBMs show geographic variations: (i) in south China, PTBMs are mostly thrombolites in open shelf settings, largely recrystallised, with remnant structure of Renalcis-group calcimicrobes; (ii) in south Turkey, in shallow waters, stromatolites and thrombolites, lacking calcimicrobes, are interbedded, likely depth-controlled; and (iii) in the Middle East, especially Iran, stromatolites and thrombolites (calcimicrobes uncommon) occur in different sites on open shelves, where controls are unclear. Thus, PTBMs were under more complex control than previously portrayed, with local facies control playing a significant role in their structure and composition. © 2011 Blackwell Publishing Ltd.
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NASA Astrophysics Data System (ADS)
Fantini, Sergio; Hueber, Dennis; Franceschini, Maria Angela; Gratton, Enrico; Rosenfeld, Warren; Stubblefield, Phillip G.; Maulik, Dev; Stankovic, Miljan R.
1999-06-01
We have used continuous-wave (CW) and frequency-domain spectroscopy to investigate the optical properties of the newborn piglet brain in vivo and non-invasively. Three anaesthetized, intubated, ventilated and instrumented newborn piglets were placed into a stereotaxic instrument for optimal experimental stability, reproducible probe-to-scalp optical contact and 3D adjustment of the optical probe. By measuring the absolute values of the brain absorption and reduced scattering coefficients at two wavelengths (758 and 830 nm), frequency-domain spectroscopy provided absolute readings (in contrast to the relative readings of CW spectroscopy) of cerebral haemoglobin concentration and saturation during experimentally induced perturbations in cerebral haemodynamics and oxygenation. Such perturbations included a modulation of the inspired oxygen concentration, transient brain asphyxia, carotid artery occlusion and terminal brain asphyxia. The baseline cerebral haemoglobin saturation and concentration, measured with frequency-domain spectroscopy, were about 60% and 42 µM respectively. The cerebral saturation values ranged from a minimum of 17% (during transient brain asphyxia) to a maximum of 80% (during recovery from transient brain asphyxia). To analyse the CW optical data, we have (a) derived a mathematical relationship between the cerebral optical properties and the differential pathlength factor and (b) introduced a method based on the spatial dependence of the detected intensity (dc slope method). The analysis of the cerebral optical signals associated with the arterial pulse and with respiration demonstrates that motion artefacts can significantly affect the intensity recorded from a single optode pair. Motion artefacts can be strongly reduced by combining data from multiple optodes to provide relative readings in the dc slope method. We also report significant biphasic changes (initial decrease and successive increase) in the reduced scattering coefficient measured in the brain after the piglet had been sacrificed.
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Venous saturation and blood flow behavior during laser-induced photodissociation of oxyhemoglobin
NASA Astrophysics Data System (ADS)
Mamilov, S. A.; Yesman, S. S.; Asimov, M. M.; Gisbrecht, A. I.
2013-03-01
The value of relative oxyhemoglobin concentration (saturation) in arterial (SаO2) and venous blood (SvO2) plays a significant role in the oxygen exchange in tissue and is used as criterion of delivery of oxygen adequate to the needs of tissue cells. Reduction of the volume of blood flows as well as reduction of oxygen concentration in arterial blood causes hypoxia - deficit of oxygen in tissue. One of the main mechanisms of elimination of hypoxia is based on compensation of the oxygen deficit by increasing the oxygen extraction from arterial blood, which leads to reduction of oxygen in the venous blood 1. In this report two optical techniques for measurement of venous blood saturation are presented. The first one is based on the pulseoximetry with artificial mechanical modulation of the tissue volume and the second one on the spectrophotometry of human respiratory rhythm. Good correlation between the results obtained with both techniques is observed.
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Noninvasive measurement of internal jugular venous oxygen saturation by photoacoustic imaging
NASA Astrophysics Data System (ADS)
Garcia-Uribe, Alejandro; Erpelding, Todd N.; Ke, Haixin; Reddy, Kavya; Sharma, Anshuman; Wang, Lihong V.
2014-03-01
The metabolic rate and oxygen consumption of the brain is reflected in jugular venous oxygen saturation. In many clinical conditions, such as head trauma, stroke, and low cardiac output states, the brain is at risk for hypoxic-ischemic injury. The current gold standard for monitoring brain oxygenation is invasive and requires jugular vein catheterization under fluoroscopic guidance; and therefore it is rarely used. Photo-acoustic tomography in combination with ultrasound can be used to estimate oxygen saturation of the internal jugular vein in real-time. This noninvasive method will enable earlier detection and prevention of impending hypoxic brain injury. A wavelength-tunable dye laser pumped by a Nd:YAG laser delivers light through an optical fiber bundle, and a modified commercial ultrasound imaging system (Philips iU22) detects both the pulse-echo ultrasound (US) and photoacoustic (PA) signals. A custom-built multichannel data acquisition system renders co-registered ultrasound and photoacoustic images at 5 frames per second. After the jugular vein was localized in healthy volunteers, dualwavelength PA images were used to calculate the blood hemoglobin oxygen saturation from the internal jugular vein in vivo. The preliminary results raise confidence that this emerging technology can be used clinically as an accurate, noninvasive indicator of cerebral oxygenation.
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Gade, John; Greisen, Gorm
2016-09-01
The study created an 'ex vivo' model to test different algorithms for measurements of mucosal haemoglobin saturation with visible light spectrophotometry (VLS). The model allowed comparison between algorithms, but it also allowed comparison with co-oximetry using a 'gold standard' method. This has not been described before. Seven pigs were used. They were perfused with cold Haemaxel, and thus killed, chilled and becoming bloodless. The bronchial artery was perfused with cold blood with known saturation and spectrophotometrical measurements were made through a bronchoscope. Based on 42 spectrophotometrical measurements of porcine bronchial mucosa saturation with fully oxygenated blood and 21 with de-oxygenated blood, six algorithms were applied to the raw-spectra of the measurements and compared with co-oxymetry. The difference from co-oxymetry in the oxygenated and de-oxygenated state ranged from -32.8 to +29.9 percentage points and from -5.0 to +9.2 percentage points, respectively. the algorithms showed remarkable in-between differences when tested on raw-spectra from an 'ex vivo' model. All algorithms had bias, more marked at high oxygenation than low oxygenation. Three algorithms were dis-recommended.
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14 CFR 121.335 - Equipment standards.
Code of Federal Regulations, 2011 CFR
2011-01-01
... Equipment standards. (a) Reciprocating engine powered airplanes. The oxygen apparatus, the minimum rates of oxygen flow, and the supply of oxygen necessary to comply with § 121.327 must meet the standards...) Turbine engine powered airplanes. The oxygen apparatus, the minimum rate of oxygen flow, and the supply of...
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14 CFR 121.335 - Equipment standards.
Code of Federal Regulations, 2013 CFR
2013-01-01
... Equipment standards. (a) Reciprocating engine powered airplanes. The oxygen apparatus, the minimum rates of oxygen flow, and the supply of oxygen necessary to comply with § 121.327 must meet the standards...) Turbine engine powered airplanes. The oxygen apparatus, the minimum rate of oxygen flow, and the supply of...
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14 CFR 121.335 - Equipment standards.
Code of Federal Regulations, 2012 CFR
2012-01-01
... Equipment standards. (a) Reciprocating engine powered airplanes. The oxygen apparatus, the minimum rates of oxygen flow, and the supply of oxygen necessary to comply with § 121.327 must meet the standards...) Turbine engine powered airplanes. The oxygen apparatus, the minimum rate of oxygen flow, and the supply of...
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14 CFR 121.335 - Equipment standards.
Code of Federal Regulations, 2010 CFR
2010-01-01
... Equipment standards. (a) Reciprocating engine powered airplanes. The oxygen apparatus, the minimum rates of oxygen flow, and the supply of oxygen necessary to comply with § 121.327 must meet the standards...) Turbine engine powered airplanes. The oxygen apparatus, the minimum rate of oxygen flow, and the supply of...
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14 CFR 121.335 - Equipment standards.
Code of Federal Regulations, 2014 CFR
2014-01-01
... Equipment standards. (a) Reciprocating engine powered airplanes. The oxygen apparatus, the minimum rates of oxygen flow, and the supply of oxygen necessary to comply with § 121.327 must meet the standards...) Turbine engine powered airplanes. The oxygen apparatus, the minimum rate of oxygen flow, and the supply of...
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Marín-Corral, J; Claverias, L; Bodí, M; Pascual, S; Dubin, A; Gea, J; Rodriguez, A
2016-05-01
To compare rSO2 (muscle oxygen saturation index) static and dynamic variables obtained by NIRS (Near Infrared Spectroscopy) in brachioradialis muscle of septic shock patients and its prognostic implications. Prospective and observational study. Intensive care unit. Septic shock patients and healthy volunteers. The probe of a NIRS device (INVOS 5100) was placed on the brachioradialis muscle during a vascular occlusion test (VOT). Baseline, minimum and maximum rSO2 values, deoxygenation rate (DeOx), reoxygenation slope (ReOx) and delta value. Septic shock patients (n=35) had lower baseline rSO2 (63.8±12.2 vs. 69.3±3.3%, p<0.05), slower DeOx (-0.54±0.31 vs. -0.91±0.35%/s, p=0.001), slower ReOx (2.67±2.17 vs. 9.46±3.5%/s, p<0.001) and lower delta (3.25±5.71 vs. 15.1±3.9%, p<0.001) when compared to healthy subjects (n=20). Among septic shock patients, non-survivors showed lower baseline rSO2 (57.0±9.6 vs. 69.8±11.3%, p=0.001), lower minimum rSO2 (36.0±12.8 vs. 51.3±14.8%, p<0.01) and lower maximum rSO2 values (60.6±10.6 vs. 73.3±11.2%, p<0.01). Baseline rSO2 was a good mortality predictor (AUC 0.79; 95%CI: 0.63-0.94, p<0.01). Dynamic parameters obtained with VOT did not improve the results. Septic shock patients present an important alteration of microcirculation that can be evaluated by NIRS with prognostic implications. Monitoring microvascular reactivity in the brachioradialis muscle using VOT with our device does not seem to improve the prognostic value of baseline rSO2. Copyright © 2015 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.
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NASA Astrophysics Data System (ADS)
Lajaunie-Salla, Katixa; Wild-Allen, Karen; Sottolichio, Aldo; Thouvenin, Bénédicte; Litrico, Xavier; Abril, Gwenaël
2017-10-01
Estuaries are increasingly degraded due to coastal urban development and are prone to hypoxia problems. The macro-tidal Gironde Estuary is characterized by a highly concentrated turbidity maximum zone (TMZ). Field observations show that hypoxia occurs in summer in the TMZ at low river flow and a few days after the spring tide peak. In situ data highlight lower dissolved oxygen (DO) concentrations around the city of Bordeaux, located in the upper estuary. Interactions between multiple factors limit the understanding of the processes controlling the dynamics of hypoxia. A 3D biogeochemical model was developed, coupled with hydrodynamics and a sediment transport model, to assess the contribution of the TMZ and the impact of urban effluents through wastewater treatment plants (WWTPs) and sewage overflows (SOs) on hypoxia. Our model describes the transport of solutes and suspended material and the biogeochemical mechanisms impacting oxygen: primary production, degradation of all organic matter (i.e. including phytoplankton respiration, degradation of river and urban watershed matter), nitrification and gas exchange. The composition and the degradation rates of each variable were characterized by in situ measurements and experimental data from the study area. The DO model was validated against observations in Bordeaux City. The simulated DO concentrations show good agreement with field observations and satisfactorily reproduce the seasonal and neap-spring time scale variations around the city of Bordeaux. Simulations show a spatial and temporal correlation between the formation of summer hypoxia and the location of the TMZ, with minimum DO centered in the vicinity of Bordeaux. To understand the contribution of the urban watershed forcing, different simulations with the presence or absence of urban effluents were compared. Our results show that in summer, a reduction of POC from SO would increase the DO minimum in the vicinity of Bordeaux by 3% of saturation. Omitting discharge from SO and WWTPs, DO would improve by 10% of saturation and mitigate hypoxic events.
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Prevalence of Prehospital Hypoxemia and Oxygen Use in Trauma Patients
2013-10-01
and included participants by applying a study-specific pulse oximeter (Nonin PalmSat 2500; Nonin Medical, Plymouth, Minnesota); this oximeter is...of week. In addition, the heart rate and oxygen saturation mea- sures that were recorded by the study-specific pulse oximeter were downloaded. After...Supplemental Oxygen Administration 95% cr N % Lower Upper Pulse Oximeter Oxygen 86 38.4 32.2 44.9 Saturation :0;90% (Hypoxemia) TBI 22 9.8 6.5 14.3
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NASA Astrophysics Data System (ADS)
Addison, Paul S.; Watson, James N.
2004-11-01
We present a novel time-frequency method for the measurement of oxygen saturation using the photoplethysmogram (PPG) signals from a standard pulse oximeter machine. The method utilizes the time-frequency transformation of the red and infrared PPGs to derive a 3D Lissajous figure. By selecting the optimal Lissajous, the method provides an inherently robust basis for the determination of oxygen saturation as regions of the time-frequency plane where high- and low-frequency signal artefacts are to be found are automatically avoided.
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2013-03-30
canvas sling. Heart rate, respiration rate, and oxygen saturation were monitored continuously using a pulse oximeter (VetOx G2 Digital, Heska Corporation...Pre Post 30 min Mean SD Median Range Mean SD Median Range Mean SD Median Range Oxygen saturation % 93.7 2.1 93.7 91–97 63.2* 17.4 66.5 36.7–91.3 92.2...as actin in human RBC membranes [29] and human neutrophils [34]. Discussion General findings Changes in heart rate, venous-blood oxygen saturation
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Proof of concept non-invasive estimation of peripheral venous oxygen saturation.
Khan, Musabbir; Pretty, Chris G; Amies, Alexander C; Balmer, Joel; Banna, Houda E; Shaw, Geoffrey M; Geoffrey Chase, J
2017-05-19
Pulse oximeters continuously monitor arterial oxygen saturation. Continuous monitoring of venous oxygen saturation (SvO 2 ) would enable real-time assessment of tissue oxygen extraction (O 2 E) and perfusion changes leading to improved diagnosis of clinical conditions, such as sepsis. This study presents the proof of concept of a novel pulse oximeter method that utilises the compliance difference between arteries and veins to induce artificial respiration-like modulations to the peripheral vasculature. These modulations make the venous blood pulsatile, which are then detected by a pulse oximeter sensor. The resulting photoplethysmograph (PPG) signals from the pulse oximeter are processed and analysed to develop a calibration model to estimate regional venous oxygen saturation (SpvO 2 ), in parallel to arterial oxygen saturation estimation (SpaO 2 ). A clinical study with healthy adult volunteers (n = 8) was conducted to assess peripheral SvO 2 using this pulse oximeter method. A range of physiologically realistic SvO 2 values were induced using arm lift and vascular occlusion tests. Gold standard, arterial and venous blood gas measurements were used as reference measurements. Modulation ratios related to arterial and venous systems were determined using a frequency domain analysis of the PPG signals. A strong, linear correlation (r 2 = 0.95) was found between estimated venous modulation ratio (R Ven ) and measured SvO 2 , providing a calibration curve relating measured R Ven to venous oxygen saturation. There is a significant difference in gradient between the SpvO 2 estimation model (SpvO 2 = 111 - 40.6*R) and the empirical SpaO 2 estimation model (SpaO 2 = 110 - 25*R), which yields the expected arterial-venous differences. Median venous and arterial oxygen saturation accuracies of paired measurements between pulse oximeter estimated and gold standard measurements were 0.29 and 0.65%, respectively, showing good accuracy of the pulse oximeter system. The main outcome of this study is the proof of concept validation of a novel pulse oximeter sensor and calibration model to assess peripheral SvO 2 , and thus O 2 E, using the method used in this study. Further validation, improvement, and application of this model can aid in clinical diagnosis of microcirculation failures due to alterations in oxygen extraction.
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NASA Astrophysics Data System (ADS)
Kleshnin, Mikhail; Orlova, Anna; Kirillin, Mikhail; Golubiatnikov, German; Turchin, Ilya
2017-07-01
A new approach to optical measuring blood oxygen saturation was developed and implemented. This technique is based on an original three-stage algorithm for reconstructing the relative concentration of biological chromophores (hemoglobin, water, lipids) from the measured spectra of diffusely scattered light at different distances from the probing radiation source. The numerical experiments and approbation of the proposed technique on a biological phantom have shown the high reconstruction accuracy and the possibility of correct calculation of hemoglobin oxygenation in the presence of additive noise and calibration errors. The obtained results of animal studies have agreed with the previously published results of other research groups and demonstrated the possibility to apply the developed technique to monitor oxygen saturation in tumor tissue.
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14 CFR 23.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2010 CFR
2010-01-01
... discretion. (c) If first-aid oxygen equipment is installed, the minimum mass flow of oxygen to each user may... upon an average flow rate of 3 liters per minute per person for whom first-aid oxygen is required. (d...
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Optical fiber-mediated photosynthesis for enhanced subsurface oxygen delivery.
Lanzarini-Lopes, Mariana; Delgado, Anca G; Guo, Yuanming; Dahlen, Paul; Westerhoff, Paul
2018-03-01
Remediation of polluted groundwater often requires oxygen delivery into subsurface to sustain aerobic bacteria. Air sparging or injection of oxygen containing solutions (e.g., hydrogen peroxide) into the subsurface are common. In this study visible light was delivered into the subsurface using radially emitting optical fibers. Phototrophic organisms grew near the optical fiber in a saturated sand column. When applying light in on-off cycles, dissolved oxygen (DO) varied from super saturation levels of >15 mg DO/L in presence of light to under-saturation (<5 mg DO/L) in absence of light. Non-photosynthetic bacteria dominated at longer radial distances from the fiber, presumably supported by soluble microbial products produced by the photosynthetic microorganisms. The dissolved oxygen variations alter redox condition changes in response to light demonstrate the potential to biologically deliver oxygen into the subsurface and support a diverse microbial community. The ability to deliver oxygen and modulate redox conditions on diurnal cycles using solar light may provide a sustainable, long term strategy for increasing dissolved oxygen levels in subsurface environments and maintaining diverse biological communities. Copyright © 2017 Elsevier Ltd. All rights reserved.
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NASA Astrophysics Data System (ADS)
Dunaev, Andrey V.; Sidorov, Victor V.; Krupatkin, Alexander I.; Rafailov, Ilya E.; Palmer, Scott G.; Sokolovski, Sergei G.; Stewart, Neil A.; Rafailov, Edik U.
2014-02-01
Multi-functional laser non-invasive diagnostic systems, such as "LAKK-M", allow the study of a number of microcirculatory parameters, including blood microcirculatory index (Im) (by laser Doppler flowmetry, LDF) and oxygen saturation (StO2) of skin tissue (by tissue reflectance oximetry, TRO). Such systems may provide significant information relevant to physiology and clinical medicine. The aim of this research was to use such a system to study the synchronization of microvascular blood flow and oxygen saturation rhythms under normal and adaptive change conditions. Studies were conducted with 8 healthy volunteers - 3 females and 5 males of 21-49 years. Each volunteer was subjected to basic 3 minute tests. The volunteers were observed for between 1-4 months each, totalling 422 basic tests. Measurements were performed on the palmar surface of the right middle finger and the forearm medial surface. Wavelet analysis was used to study rhythmic oscillations in LDF- and TRO-data. Tissue oxygen consumption (from arterial and venal blood oxygen saturation and nutritive flux volume) was calculated for all volunteers during "adaptive changes" as (617+/-123 AU) and (102+/-38 AU) with and without arteriovenous anastomoses (AVAs) respectively. This demonstrates increased consumption compared to normal (495+/-170 AU) and (69+/-40 AU) with and without AVAs respectively. Data analysis demonstrated the emergence of resonance and synchronization of rhythms of microvascular blood flow and oxygen saturation as an adaptive change in myogenic oscillation (vasomotion) resulting from exercise and potentially from psychoemotional stress. Synchronization of myogenic rhythms during adaptive changes suggest increased oxygen consumption resulting from increased microvascular blood flow velocity.
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Zhu, Mingshan; Zeng, Bixin
2015-03-01
In this paper, we designed an oxygen saturation, heart rate, respiration rate monitoring system based on smartphone of android operating system, physiological signal acquired by MSP430 microcontroller and transmitted by Bluetooth module.
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Blake, E; Allen, J; Thorn, C; Shore, A; Curnow, A
2013-05-01
Methyl aminolevulinate photodynamic therapy (MAL-PDT) (a topical treatment used for a number of precancerous skin conditions) utilizes the combined interaction of a photosensitizer (protoporphyrin IX (PpIX)), light of the appropriate wavelength, and molecular oxygen to produce singlet oxygen and other reactive oxygen species which induce cell death. During treatment, localized oxygen depletion occurs and is thought to contribute to decreased efficacy. The aim of this study was to investigate whether an oxygen pressure injection (OPI) device had an effect on localized oxygen saturation levels and/or PpIX fluorescence of skin lesions during MAL-PDT. This study employed an OPI device to apply oxygen under pressure to the skin lesions of patients undergoing standard MAL-PDT. Optical reflectance spectrometry and fluorescence imaging were used to noninvasively monitor the localized oxygen saturation and PpIX fluorescence of the treatment area, respectively. No significant changes in oxygen saturation were observed when these data were combined for the group with OPI and compared to the group that received standard MAL-PDT without OPI. Additionally, no significant difference in PpIX photobleaching or clinical outcome at 3 months between the groups of patients was observed, although the group that received standard MAL-PDT demonstrated a significant increase (p<0.05) in PpIX fluorescence initially and both groups produced a significant decrease (p<0.05) after light irradiation. In conclusion, with this sample size, this OPI device was not found to be an effective method with which to improve tissue oxygenation during MAL-PDT. Further investigation is therefore required to find a more effective method of MAL-PDT enhancement.
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NASA Technical Reports Server (NTRS)
Breit, G. A.; Gross, J. H.; Watenpaugh, D. E.; Chance, B.; Hargens, A. R.
1997-01-01
Variations in the levels of muscle hemoglobin and of myoglobin oxygen saturation can be detected non-invasively with near-infrared spectroscopy. This technique could be applied to the diagnosis of chronic compartment syndrome, in which invasive testing has shown increased intramuscular pressure associated with ischemia and pain during exercise. We simulated chronic compartment syndrome in ten healthy subjects (seven men and three women) by applying external compression, through a wide inflatable cuff, to increase the intramuscular pressure in the anterior compartment of the leg. The tissue oxygenation of the tibialis anterior muscle was measured with near-infrared spectroscopy during gradual inflation of the cuff to a pressure of forty millimeters of mercury (5.33 kilopascals) during fourteen minutes of cyclic isokinetic dorsiflexion and plantar flexion of the ankle. The subjects exercised with and without external compression. The data on tissue oxygenation for each subject then were normalized to a scale of 100 per cent (the baseline value, or the value at rest) to 0 per cent (the physiological minimum, or the level of oxygenation achieved by exercise to exhaustion during arterial occlusion of the lower extremity). With external compression, tissue oxygenation declined at a rate of 1.4 +/- 0.3 per cent per minute (mean and standard error) during exercise. After an initial decrease at the onset, tissue oxygenation did not decline during exercise without compression. The recovery of tissue oxygenation after exercise was twice as slow with compression (2.5 +/- 0.6 minutes) than it was without the use of compression (1.3 +/- 0.2 minutes).
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NASA Technical Reports Server (NTRS)
Harper, Susana; Smith, Sarah; Juarez, Alfredo; Hirsch, David
2010-01-01
Increased human spaceflight operations utilize oxygen concentrations that are frequently varied with use of concentrations up to 100 percent oxygen. Even after exiting a higher percentage oxygen environment, high oxygen concentrations can still be maintained due to material saturation and oxygen entrapment between barrier materials. This paper examines the material flammability concerns that arise from changing oxygen environments during spaceflight operations. We examine the time required for common spacecraft and spacesuit materials exposed to oxygen to return to reduced ignitability and flammability once removed from the increased concentration. Various common spacecraft materials were considered: spacecraft cabin environment foams, Extra Vehicular Mobility Unit materials and foams, Advanced Crew Escape Suit materials, and other materials of interest such as Cotton, Nomex^ HT90-40, and Tiburon Surgical Drape. This paper presents calculated diffusion coefficients derived from experimentally obtained oxygen transmission rates for the tested materials and the analytically derived times necessary for reduced flammability to be achieved based on NASA flammability criteria. Oxygen material saturation and entrapment scenarios are examined. Experimental verification data on oxygen diffusion in saturation scenarios are also presented and discussed. We examine how to use obtained data to address flammability concerns during operational planning to reduce the likelihood of fires while improving efficiency for procedures.
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Nocturnal oxygen saturation in children with stable cystic fibrosis.
van der Giessen, Lianne; Bakker, Marije; Joosten, Koen; Hop, Wim; Tiddens, Harm
2012-11-01
Hypoxemia during sleep is a common finding in Cystic Fibrosis (CF) patients with more advanced lung disease. Nocturnal hypoxemia is associated with frequent awakenings and poor sleep quality. For children with CF, data of nocturnal oxygen saturation are sparse. To assess the oxygen saturation profile during sleep in 25 clinically stable children with CF lung disease and to correlate these data with spirometry, cough frequency, sleep quality, and CT-scan scores. During two nights cough was recorded with a digital audio recorder in 25 clinically stable CF patients. In addition oxygen saturation was measured. The day following the recording spirometry was carried out. CT scores were obtained from the most recent routine CT scan. Twenty-two patients were included in the study. Mean age (range) was 13 (6-18) years. Spirometry was FVC% 84 (range 52-114), FEV(1) % 77 (range 43-115), and FEF(75) % 50 (range 12-112). The mean SO(2) was 95.6% for the first and 96.2% for the second night. Mean SO(2) between the two nights correlated strongly (r(s) = 0.84, P < 0.001). Positive correlation was observed between mean SO(2) of the two nights (mean × SO(2)) and FVC, FEV(1) and FEF(75). Correlations were found between mean × SO(2) and the total CT score (r(s) = -0.45, P = 0.05) and the bronchiectasis subscore (r(s) = -0.48, P = 0.03). Nocturnal oxygen saturation in children with stable CF is lower than that in healthy children, and is correlated with lung function parameters and CT scores. Monitoring oxygen saturation during one night is sufficient to get a representative recording. Copyright © 2012 Wiley Periodicals, Inc.
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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.
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Li, Walter; Niu, Bolin; Henderson, Katherine; Northrup, Veronika; Pollak, Jeffery S; Trow, Terence; Fahey, John; White, Robert I
2011-06-01
Patients with pulmonary arteriovenous malformations (PAVMs) are at risk for multiple complications and require close follow-up. We investigated the reproducibility of the 6-minute walk test (6MWT) and exercise stress test (EST) for the evaluation of low oxygen saturation in patients with PAVMs. Twenty-two patients with PAVMs, most of whom had hereditary hemorrhagic telangiectasia (HHT), participated in a Human Investigations Committee-approved protocol. Patients ranged from 9 to 74 years of age (mean 28) and had a broad spectrum of anatomic subtypes of PAVMs, including focal and diffuse. Standard 6MWT and cycle ergometry EST were both performed twice with adequate rest between tests. Heart rate (HR) and oxygen saturation were measured at the beginning and end of each test. Distance walked and maximum resistance was also recorded. The intraclass correlation coefficients (r(i)) at the end of 6MWT were as follows: HR (r(i) = 0.940; 95% confidence interval [CI] 0.863-0.975), oxygen saturation (r(i) = 0.973; 95% CI 0.933-0.989), and distance (r(i) = 0.942; 95% CI 0.867-0.975). The r(i)s at the end of EST were as follows: HR (r(i) = 0.941; 95% CI 0.865-0.975), oxygen saturation (r(i) = 0.993; 95% CI 0.982-0.997), and maximum resistance (r(i) = 0.941; 95% CI 0.864-0.975). 6MWT and EST were reproducible measures of exercise capacity and oxygen saturation and are potential adjunct tests in the follow-up assessment for patients with PAVMs.
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Oxygen Saturation in Closed-Globe Blunt Ocular Trauma
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
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Wang, Yu; Hu, Song; Maslov, Konstantin; Zhang, Yu; Xia, Younan; Wang, Lihong V
2011-04-01
We developed dual-modality microscope integrating photoacoustic microscopy (PAM) and fluorescence confocal microscopy (FCM) to noninvasively image hemoglobin oxygen saturation (sO₂) and oxygen partial pressure (pO₂) in vivo in single blood vessels with high spatial resolution. While PAM measures sO₂ by imaging hemoglobin optical absorption at two wavelengths, FCM quantifies pO₂ using phosphorescence quenching. The variations of sO₂ and pO₂ values in multiple orders of vessel branches under hyperoxic (100% oxygen) and normoxic (21% oxygen) conditions correlate well with the oxygen-hemoglobin dissociation curve. In addition, the total concentration of hemoglobin is imaged by PAM at an isosbestic wavelength.
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[Low flow anaesthesia with isoflurane and sevoflurane in the dog].
Kramer, Sabine; Alyakine, Hassan; Nolte, Ingo
2008-01-01
The aim of the present study was to compare the safety and efficacy of sevoflurane and isoflurane during low flow anaesthesia (fresh gas flow (FGF) 14 ml/kg/min) as well as to compare the consumption of both anaesthetics. Data were gathered from 60 dogs assigned for surgery under general anaesthesia with an expected duration of 75 minutes or longer. All dogs were induced with 0.6 mg/kg (maximum 25 mg) l-methadone and 1 mg/kg (maximum 25 mg) diazepam i.v.. Anaesthesia was maintained with isoflurane (group 1) or sevoflurane (group 2) in a mixture with 50% O2 and 50% N2O as carrier gases, under controlled ventilation. Monitoring included electrocardiogram, body temperature, the temperature of in- and exspired gases, arterial oxygen saturation, arterial blood pressure as well as a continuous monitoring of inhaled and exhaled gas concentrations (O2, N2O, CO2, isoflurane, sevoflurane). The consumption of isoflurane and sevoflurane as well as the dogs' recovery times were evaluated for both groups. In all groups the inspired oxygen concentrations ranged above the minimum value of 30 Vol% during low flow anaesthesia, with an arterial oxygen saturation above 97%. End tidal concentration of CO2, heart rate and arterial blood pressure were within the physiological ranges and showed no differences between the two groups. Recovery time was significantly shorter after sevoflurane compared to isoflurane anaesthesia, whilst the consumption of sevoflurane was higher than that of isoflurane. Sevoflurane appears to be as clinically safe as isoflurane in low flow anaesthesia. Even considering that sevoflurane is more expensive than isoflurane, the use of the low flow technique decreases the cost of anaesthesia due to the reduced volatile anaesthetic consumption.
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[Low flow anaesthesia with isoflurane in the dog].
Kramer, Sabine; Alyakine, Hassan; Nolte, Ingo
2005-01-01
The aim of the present study was to compare the safety of two low flow (LF) regimes [fresh gas flow (FGF) 20 ml/kg/min (group 2) and 14 ml/kg/min (group 3)] with the high flow (HF) technique (FGF 50 ml/kg/min; group 1) of isoflurane anaesthesia. Data were gathered from ninety dogs assigned for surgery under general anaesthesia with an expected duration of 75 minutes or longer. All dogs had an anaesthetic induction with 0,6 mg/kg I-methadone (maximum 25 mg) and 1 mg/kg diazepam (maximum 25 mg) i.v. Anaesthesia was maintained with isoflurane in a mixture of 50% O2 and 50% N2O as carrier gases, with controlled ventilation. The Monitoring included electrocardiogramm, body temperature, the temperature of in- and exspired gases, arterial oxygen saturation, arterial blood pressure as well as a continuous monitoring of inhaled and exhaled gas concentrations (O2, N2O, CO2, isoflurane). The consumption of isoflurane and carrier gases as well as the recovery times were evaluated for the three groups. The inspired oxygen concentrations always ranged above the minimum value of 30 Vol.-% during low flow anaesthesia. The arterial oxygen saturation ranged between 92-98%, the end tidal concentration of CO2 between 35 and 45 mmHg. Heart rate and arterial blood pressure were within normal limits. Recovery time was significantly shorter after LF than after HF anaesthesia. The highest decrease in body temperature occurred in the HF group 1 because of a significantly lower anaesthetic gas temperature. Despite this, LF anaesthesia resulted in a reduced consumption of carrier gases and volatiles. In conclusion, low flow anaesthesia with isoflurane is a safe technique and offers substantial economic advantages over high flow techniques and is moreover better tolerated by the patients.
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NASA Astrophysics Data System (ADS)
Norzagaray, O.; Martin Hernandez-Ayon, J. M.; Calderon Aguilera, L. E.; Reyes-Bonilla, H.; Castro, R.; Trasviña, A.
2016-02-01
Cabo Pulmo reef is located in the coastal area within the oxygen minimum zone (OMZ), which has been reported as shallow as 70m, and characterized by CO2-rich waters (>2200 μmolkg-1) and low pH (<7.7). To date it is unknown whether the OMZ waters influence these coral reef at any point of the year, or during certain oceanographic episodes, therefore, it is important to know the temporal variability of these parameters. This study presents high frequency data series from November 2013 to June 2014 from a SeapHOX sensor deployed at 15 m depth and 1.5 km from shore. The pH series was calibrated with discrete samples (total carbon and alkalinity measurements). A high-resolution aragonite saturation state (< Ωar) series was calculated from pH series and total alkalinity. Discrete and continuous measurements showed the seasonal influence of two water masses, the Gulf of California water during winter (GCW), and the surface Tropical water (TSW) during spring-summer. From December to April the conditions with the lowest pH were found (<Ωar), related to GCW, and two months with TSW; the highest pH values (> Ωar) were from May to June. During winter-spring (mostly-TSW) were present the most optimal conditions for coral calcification (>Ωar). Dissolved oxygen (OD) was always up to 3.4 mlL-1. However, two events (5-10 days length) arose in winter (February/TSW) and summer (June/GCW) with low pH (<7.9), low Ωar (<2.6), low temperature (<22oC), and low DO (<4 mlL-1), threshold values reported to cause negative effects on coral calcification and with exposure times on the order of days.
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Wood, Andrew T; Clark, Timothy D; Andrewartha, Sarah J; Elliott, Nicholas G; Frappell, Peter B
Exposure to developmental hypoxia can have long-term impacts on the physiological performance of fish because of irreversible plasticity. Wild and captive-reared Atlantic salmon (Salmo salar) can be exposed to hypoxic conditions during development and continue to experience fluctuating oxygen levels as juveniles and adults. Here, we examine whether developmental hypoxia impacts subsequent hypoxia tolerance and aerobic performance of Atlantic salmon. Individuals at 8°C were exposed to 50% (hypoxia) or 100% (normoxia) dissolved oxygen (DO) saturation (as percent of air saturation) from fertilization for ∼100 d (800 degree days) and then raised in normoxic conditions for a further 15 mo. At 18 mo after fertilization, aerobic scope was calculated in normoxia (100% DO) and acute (18 h) hypoxia (50% DO) from the difference between the minimum and maximum oxygen consumption rates ([Formula: see text] and [Formula: see text], respectively) at 10°C. Hypoxia tolerance was determined as the DO at which loss of equilibrium (LOE) occurred in a constantly decreasing DO environment. There was no difference in [Formula: see text], [Formula: see text], or aerobic scope between fish raised in hypoxia or normoxia. There was some evidence that hypoxia tolerance was lower (higher DO at LOE) in hypoxia-raised fish compared with those raised in normoxia, but the magnitude of the effect was small (12.52% DO vs. 11.73% DO at LOE). Acute hypoxia significantly reduced aerobic scope by reducing [Formula: see text], while [Formula: see text] remained unchanged. Interestingly, acute hypoxia uncovered individual-level relationships between DO at LOE and [Formula: see text], [Formula: see text], and aerobic scope. We discuss our findings in the context of developmental trajectories and the role of aerobic performance in hypoxia tolerance.
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Green, W. Reed; Galloway, Joel M.; Richards, Joseph M.; Wesolowski, Edwin A.
2003-01-01
Outflow from Table Rock Lake and other White River reservoirs support a cold-water trout fishery of substantial economic yield in south-central Missouri and north-central Arkansas. The Missouri Department of Conservation has requested an increase in existing minimum flows through the Table Rock Lake Dam from the U.S. Army Corps of Engineers to increase the quality of fishable waters downstream in Lake Taneycomo. Information is needed to assess the effect of increased minimum flows on temperature and dissolved- oxygen concentrations of reservoir water and the outflow. A two-dimensional, laterally averaged, hydrodynamic, temperature, and dissolved-oxygen model, CE-QUAL-W2, was developed and calibrated for Table Rock Lake, located in Missouri, north of the Arkansas-Missouri State line. The model simulates water-surface elevation, heat transport, and dissolved-oxygen dynamics. The model was developed to assess the effects of proposed increases in minimum flow from about 4.4 cubic meters per second (the existing minimum flow) to 11.3 cubic meters per second (the increased minimum flow). Simulations included assessing the effect of (1) increased minimum flows and (2) increased minimum flows with increased water-surface elevations in Table Rock Lake, on outflow temperatures and dissolved-oxygen concentrations. In both minimum flow scenarios, water temperature appeared to stay the same or increase slightly (less than 0.37 ?C) and dissolved oxygen appeared to decrease slightly (less than 0.78 mg/L) in the outflow during the thermal stratification season. However, differences between the minimum flow scenarios for water temperature and dissolved- oxygen concentration and the calibrated model were similar to the differences between measured and simulated water-column profile values.
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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
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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.
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Aqueous pyrite oxidation by dissolved oxygen and by ferric iron
Moses, Carl O.; Nordstrom, D. Kirk; Herman, Janet S.; Mills, Aaron L.
1987-01-01
Rates of aqueous, abiotic pyrite oxidation were measured in oxygen-saturated and anaerobic Fe(III)-saturated solutions with initial pH from 2 to 9. These studies included analyses of sulfite, thiosulfate, polythionates and sulfate and procedures for cleaning oxidation products from pyrite surfaces were evaluated. Pyrite oxidation in oxygen-saturated solutions produced (1) rates that were only slightly dependent on initial pH, (2) linear increases in sulfoxy anions and (3) thiosulfate and polythionates at pH > 3.9. Intermediate sulfoxy anions were observed only at high stirring rates. In anaerobic Fe(III)-saturated solutions, no intermediates were observed except traces of sulfite at pH 9. The faster rate of oxidation in Fe(III)-saturated solutions supports a reaction mechanism in which Fe(III) is the direct oxidant of pyrite in both aerobic and anaerobic systems. The proposal of this mechanism is also supported by theoretical considerations regarding the low probability of a direct reaction between paramagnetic molecular oxygen and diamagnetic pyrite. Results from a study of sphalerite oxidation support the hypothesis that thiosulfate is a key intermediate in sulfate production, regardless of the bonding structure of the sulfide mineral.
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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.
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Use of pulse oximeter placed on a gastroschisis silo to monitor intestinal oxygen saturation.
Kim, Sunghoon; Betts, James; Yedlin, Steve; Rowe, Richard; Idowu, Olajire
2006-09-01
The use of a silo for temporary coverage of exposed viscera for newborns with gastroschisis has allowed gradual reduction of the externalized intestine into the abdominal cavity. However, there has not been an easy way to monitor blood perfusion to the intestine within the silo other than with visual examination. In addition, visual examination of bowel through the silo is sometimes difficult for medical staff due to serositis and peel over the bowel. We have adopted an approach to monitor oxygen saturation of silo-contained intestine by placing a pulse oximeter sensor on the surface of the transparent silo to detect intestinal ischemia. Pulse oximeter sensors were applied on both a patient's distal extremity and the silo on five consecutive patients who were born with gastroschisis. The sensor was left on the silo during the entire period of gradual reduction. Perfusion index, pulse and oxygen saturation were observed and checked against the sensor placed on a peripheral extremity. The silo-placed pulse oximeter and peripheral pulse oximeter sensors showed a similar pulse and oxygen saturation throughout the reduction period in all five patients. In general, perfusion index was higher from the silo pulse oximeter compared to the peripheral pulse oximeter reading. A pulse oximeter can be used to monitor intestinal oxygen saturation contained within a silo and help modulate the rate of manual reduction of intestine.
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Seibel, Brad A; Häfker, N Sören; Trübenbach, Katja; Zhang, Jing; Tessier, Shannon N; Pörtner, Hans-Otto; Rosa, Rui; Storey, Kenneth B
2014-07-15
The jumbo squid, Dosidicus gigas, can survive extended forays into the oxygen minimum zone (OMZ) of the Eastern Pacific Ocean. Previous studies have demonstrated reduced oxygen consumption and a limited anaerobic contribution to ATP production, suggesting the capacity for substantial metabolic suppression during hypoxic exposure. Here, we provide a more complete description of energy metabolism and explore the expression of proteins indicative of transcriptional and translational arrest that may contribute to metabolic suppression. We demonstrate a suppression of total ATP demand under hypoxic conditions (1% oxygen, PO2 =0.8 kPa) in both juveniles (52%) and adults (35%) of the jumbo squid. Oxygen consumption rates are reduced to 20% under hypoxia relative to air-saturated controls. Concentrations of arginine phosphate (Arg-P) and ATP declined initially, reaching a new steady state (~30% of controls) after the first hour of hypoxic exposure. Octopine began accumulating after the first hour of hypoxic exposure, once Arg-P breakdown resulted in sufficient free arginine for substrate. Octopine reached levels near 30 mmol g(-1) after 3.4 h of hypoxic exposure. Succinate did increase through hypoxia but contributed minimally to total ATP production. Glycogenolysis in mantle muscle presumably serves to maintain muscle functionality and balance energetics during hypoxia. We provide evidence that post-translational modifications on histone proteins and translation factors serve as a primary means of energy conservation and that select components of the stress response are altered in hypoxic squids. Reduced ATP consumption under hypoxia serves to maintain ATP levels, prolong fuel store use and minimize the accumulation of acidic intermediates of anaerobic ATP-generating pathways during prolonged diel forays into the OMZ. Metabolic suppression likely limits active, daytime foraging at depth in the core of the OMZ, but confers an energetic advantage over competitors that must remain in warm, oxygenated surface waters. Moreover, the capacity for metabolic suppression provides habitat flexibility as OMZs expand as a result of climate change. © 2014. Published by The Company of Biologists Ltd.
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Bronicki, Ronald A; Checchia, Paul A; Anas, Nick G; Adams, Gerald J; Penny, Daniel J; Bleiweis, Mark S; Shekerdemian, Lara S
2013-02-01
After repair of tetralogy of Fallot, some patients experience a low cardiac output state owing to right ventricular diastolic failure. Negative-pressure ventilation has been shown to improve cardiac output in these patients. What has not been evaluated is the effect of extubation and loading of the respiratory muscles on the distribution of cardiac output after repair of tetralogy of Fallot. In 23 consecutive patients undergoing repair of tetralogy of Fallot, standard hemodynamic variables, central venous oxygen saturations, and near infrared spectroscopy of the brain, mesenteric, and renal circulations were monitored for 30 minutes before and after extubation. With extubation, the systolic blood pressure increased significantly from 96 ± 11 to 106 ± 15 mm Hg (p = 0.002) while the heart rate remained unchanged. With extubation, the central venous oxygen saturation increased significantly from 65% ± 7% to 70% ± 10% (p = 0.003). Cerebral oxygen saturations increased significantly from 67% ± 10% to 72% ± 9% (p = 0.0001), whereas mesenteric oxygenation fell significantly from 74% ± 15% to 72% ± 15% (p = 0.04). Renal oxygenation was unaffected by extubation. Cardiac output and cerebral oxygenation increased significantly during spontaneous respiration, the latter suggesting that the brain was in or approaching an oxygen supply-dependent state before extubation. Despite the increase in cardiac output, the presumed increase in respiratory pump perfusion, as well as the concurrent increase in cerebral perfusion, came at the expense of mesenteric perfusion. Renal oxygenation remained unchanged with extubation. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.
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Chen, Zhongjiang; Yang, Sihua; Xing, Da
2012-08-15
A method for noninvasively detecting hemoglobin oxygen saturation (SO2) and carboxyhemoglobin saturation (SCO) in subcutaneous microvasculature with multiwavelength photoacoustic microscopy is presented. Blood samples mixed with different concentrations of carboxyhemoglobin were used to test the feasibility and accuracy of photoacoustic microscopy compared with the blood-gas analyzer. Moreover, fixed-point detection of SO2 and SCO in mouse ear was obtained, and the changes from normoxia to carbon monoxide hypoxia were dynamically monitored in vivo. Experimental results demonstrate that multiwavelength photoacoustic microscopy can detect SO2 and SCO, which has future potential clinical applications.
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The role of pulse oximetry in chiropractic practice: a rationale for its use
Hall, Michael W.; Jensen, Anne M.
2012-01-01
Objective Pulse oximetry is used regularly to assess oxygen saturation levels. The objective of this commentary is to discuss a rationale for using pulse oximetry in chiropractic practice. Discussion Pulse oximetry may offer doctors of chiropractic a way to monitor patients' oxygen saturation levels. Quantification of saturation values with heart rate may give clinical aid to the management of chiropractic patients. Markedly reduced saturation levels may necessitate medical referral, whereas mildly reduced levels could lead to changes in chiropractic management. Conclusions Pulse oximetry has the potential to be an integral part of chiropractic practice. PMID:23204957
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Reproducibility of retinal vessel oxygen saturation measurements in healthy young subjects.
Lasta, Michael; Palkovits, Stefan; Boltz, Agnes; Schmidl, Doreen; Kaya, Semira; Cherecheanu, Alina Popa; Garhöfer, Gerhard; Schmetterer, Leopold
2012-12-01
An adequate oxygenation and perfusion is essential for the function of the inner retina. Recently, several techniques for the measurement of retinal oxygen saturation became available. We set out to evaluate reproducibility of the measurements using a modified Retinal Vessel Analyzer. A total of 20 healthy female and male subjects aged between 18 and 35 years (22.9 ± 3.9; mean ± SD) were included. The measurement of retinal oxygen saturation with the retinal oximeter employed in this study is based on optical reflectometry using the different absorption characteristics of oxygenated and deoxygenated haemoglobin. The intraclass correlation coefficients and the coefficients of variation (CV) for test-retest, short-term as well as day-to-day measurements were calculated. The intraclass correlation coefficients were between 0.91 and 0.94 for retinal branch arteries and between 0.84 and 0.88 for retinal branch veins. In retinal arteries, we calculated a test-retest CV of 3.24 ± 3.18% for oxygen saturation measurements. In retinal veins, data were slightly less reproducible with a CV of 4.92 ± 3.57%. Short-term reproducibility of both measurement cycles on each study day was in the same range (CV in retinal arteries: 2.91 ± 2.42% and CV in retinal veins: 4.76 ± 3.14%). The day-to-day coefficient of variation was slightly higher (CV in retinal arteries: 3.97 ± 2.87% and CV in retinal veins: 6.18 ± 3.36%). The reproducibility of haemoglobin oxygen saturation measurements using the retinal oximeter is acceptable. Further studies on the validity of the obtained results are, however, required. © 2012 The Authors. Acta Ophthalmologica © 2012 Acta Ophthalmologica Scandinavica Foundation.
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Lung vital capacity and oxygen saturation in adults with cerebral palsy
Lampe, Renée; Blumenstein, Tobias; Turova, Varvara; Alves-Pinto, Ana
2014-01-01
Background Individuals with infantile cerebral palsy have multiple disabilities. The most conspicuous syndrome being investigated from many aspects is motor movement disorder with a spastic gait pattern. The lung function of adults with spasticity attracts less attention in the literature. This is surprising because decreased thoracic mobility and longstanding scoliosis should have an impact on lung function. With increasing age and the level of disability, individuals become susceptible to lung infections and reflux illness, and these are accompanied by increased aspiration risk. This study examined, with different methods, to what extent adults with congenital cerebral palsy and acquired spastic paresis – following traumatic brain injury – showed restriction of lung function. It also assessed the contribution of disability level on this restriction. Methods The oxygen saturation of 46 adults with a diagnosis of cerebral palsy was measured with an oximeter. Lung vital capacity was measured with a mobile spirometer and excursion of the thorax was clinically registered. The gross motor function levels and the presence or absence of scoliosis were determined. Results A significantly positive correlation between lung vital capacity and chest expansion was established. Both the lung vital capacity and the thorax excursion decreased with increases in gross motor function level. Oxygen saturation remained within the normal range in all persons, in spite of reduced values of the measured lung parameters. No statistically significant dependency between lung vital capacity and oxygen saturation, and between chest expansion and oxygen saturation was found. The scoliotic deformities of the spine were associated with an additional decrease in the vital capacity, but this did not affect blood oxygen supply. Conclusion Despite the decreased chest expansion and the significantly reduced lung volume in adults with cerebral palsy, sufficient oxygen supply was registered. PMID:25525345
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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.
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Multimodal optical imaging of microvessel network convective oxygen transport dynamics.
Dedeugd, Casey; Wankhede, Mamta; Sorg, Brian S
2009-04-01
Convective oxygen transport by microvessels depends on several parameters, including red blood cell flux and oxygen saturation. We demonstrate the use of intravital microscopy techniques to measure hemoglobin saturations, red blood cell fluxes and velocities, and microvessel cross-sectional areas in regions of microvascular networks containing multiple vessels. With these methods, data can be obtained at high spatial and temporal resolution and correlations between oxygen transport and hemodynamic parameters can be assessed. In vivo data are presented for a mouse mammary adenocarcinoma grown in a dorsal skinfold window chamber model.
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Xia, Shuang; Utriainen, David; Tang, Jin; Kou, Zhifeng; Zheng, Gang; Wang, Xuesong; Shen, Wen; Haacke, E Mark; Lu, Guangming
2014-12-01
Decreased oxygen saturation in asymmetrically prominent cortical veins (APCV) seen in ischemic stroke has been hypothesized to correlate with an increase of de-oxygenated hemoglobin. Our goal is to quantify magnetic susceptibility to define APCV by establishing a cutoff above which the deoxyhemoglobin levels are considered abnormal. A retrospective study was conducted on 26 patients with acute ischemic stroke in one cerebral hemisphere that exhibited APCV with 30 age- and sex-matched healthy controls. Quantitative susceptibility mapping (QSM) was used to calculate the magnetic susceptibility of the cortical veins. A paired t-test was used to compare the susceptibility of the cortical veins in the left and right hemispheres for healthy controls as well as in the contralateral hemisphere for stroke patients with APCV. The change in oxygen saturation in the APCV relative to the contralateral side was calculated after thresholding the susceptibility using the mean plus two standard deviations of the contralateral side for each individual. The thresholded susceptibility value of the APCVs in the stroke hemisphere was 254±48 ppb which was significantly higher (p<0.05) than that in the contralateral hemisphere (123±12 ppb) and in healthy controls (125±8 ppb). There was a decrease of oxygen saturation in the APCV ranging from 16% to 44% relative to the veins of the contralateral hemisphere. In conclusion, APCV seen in SWI correspond to reduced levels of oxygen saturation and these abnormal veins can be identified using a susceptibility threshold on the QSM data. Copyright © 2014 Elsevier Inc. All rights reserved.
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Very long apnea events in preterm infants
Vergales, Brooke D.; Lee, Hoshik; Clark, Matthew T.; Lake, Douglas E.; Mennen, Anne C.; Kattwinkel, John; Sinkin, Robert A.; Moorman, J. Randall; Fairchild, Karen D.; Delos, John B.
2014-01-01
Apnea is nearly universal among very low birth weight (VLBW) infants, and the associated bradycardia and desaturation may have detrimental consequences. We describe here very long (>60 s) central apnea events (VLAs) with bradycardia and desaturation, discovered using a computerized detection system applied to our database of over 100 infant years of electronic signals. Eighty-six VLAs occurred in 29 out of 335 VLBW infants. Eighteen of the 29 infants had a clinical event or condition possibly related to the VLA. Most VLAs occurred while infants were on nasal continuous positive airway pressure, supplemental oxygen, and caffeine. Apnea alarms on the bedside monitor activated in 66% of events, on average 28 s after cessation of breathing. Bradycardia alarms activated late, on average 64 s after cessation of breathing. Before VLAs oxygen saturation was unusually high, and during VLAs oxygen saturation and heart rate fell unusually slowly. We give measures of the relative severity of VLAs and theoretical calculations that describe the rate of decrease of oxygen saturation. A clinical conclusion is that very long apnea (VLA) events with bradycardia and desaturation are not rare. Apnea alarms failed to activate for about one-third of VLAs. It appears that neonatal intensive care unit (NICU) personnel respond quickly to bradycardia alarms but not consistently to apnea alarms. We speculate that more reliable apnea detection systems would improve patient safety in the NICU. A physiological conclusion is that the slow decrease of oxygen saturation is consistent with a physiological model based on assumed high values of initial oxygen saturation. PMID:25549762
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Ramm, Lisa; Jentsch, Susanne; Peters, Sven; Sauer, Lydia; Augsten, Regine; Hammer, Martin
2016-05-01
To investigate the interrelationship between the oxygen supply of the retina and its regulation with the severity of primary open-angle glaucoma (POAG). Central retinal artery (CRAE) and vein (CRVE) diameters and oxygen saturation of peripapillary retinal vessels in 41 patients suffering from POAG (64.1 ± 12.9 years) and 40 healthy volunteers (63.6 ± 14.1 years) were measured using the retinal vessel analyzer. All measures were taken before and during flicker light stimulation. The mean retinal nerve fiber layer thickness (RNFLT) was determined by OCT and the visual field mean defect (MD) was identified using perimetry. In glaucoma patients, CRAE (r = -0.48 p = 0.002) and CRVE (r = -0.394 p = 0.014) at baseline were inversely related to MD, while arterial and venous oxygen saturation showed no significant dependence on the severity of the damage. However, the flicker light-induced change in arterio-venous difference in oxygen saturation was correlated with the MD (r = 0.358 p = 0.027). The diameters of arteries and veins at baseline decreased with reduction of the mean RNFLT (arteries: r = 0.718 p < 0.001; veins: r = 0.685 p < 0.001). Vessel diameters showed a strong correlation with RNFLT and MD. This, as well as the reduction of stimulation-induced change in arterio-venous oxygen saturation difference with visual field loss, may be explained by a reduction of the retinal metabolic demand with progressive loss of neuronal tissue in glaucoma. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.
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Effects of noninvasive ventilation on sleep outcomes in amyotrophic lateral sclerosis.
Katzberg, Hans D; Selegiman, Adam; Guion, Lee; Yuan, Nancy; Cho, Sungho C; Katz, Jonathan S; Miller, Robert G; So, Yuen T
2013-04-15
The objective was to study the effects on noninvasive ventilation on sleep outcomes in patient with ALS, specifically oxygenation and overall sleep quality. Patients with ALS who met criteria for initiation of NIV were studied with a series of 2 home PSG studies, one without NIV and a follow-up study while using NIV. Primary outcome was a change in the maximum overnight oxygen saturation; secondary outcomes included change in mean overnight oxygen saturation, apnea and hypopnea indexes, sleep latency, sleep efficiency, sleep arousals, and sleep architecture. A total of 94 patients with ALS were screened for eligibility; 15 were enrolled; and 12 completed study procedures. Maximum overnight oxygen saturation improved by 7.0% (p = 0.01) and by 6.7% during REM sleep (p = 0.02) with NIV. Time spent below 90% oxygen saturation was also significant-ly better with NIV (30% vs 19%, p < 0.01), and there was trend for improvement in mean overnight saturation (1.5%, p = 0.06). Apnea index (3.7 to 0.7), hypopnea index (6.2 to 5.7), and apnea hypopnea index (9.8 to 6.3) did not significantly improve after introducing NIV. NIV had no effect on sleep efficiency (mean change 10%), arousal index (7 to 12), or sleep stage distribution (Friedman chi-squared = 0.40). NIV improved oxygenation but showed no significant effects on sleep efficiency, sleep arousals, restful sleep, or sleep architecture. The net impact of these changes for patients deserves further study in a larger group of ALS patients.
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Sensing Disaster: The Use of Wearable Sensor Technology to Decrease Firefighter Line-of-Duty Deaths
2015-12-01
peripheral oxygen or SpO2), and temperature , to name but a few.164 The current GTWM allows these sensors to be plugged in anywhere on the shirt, although...desired monitoring parameters included the “heart rate, respiratory rate, body temperature , blood oxygen saturation levels, environmental...physiological tests and parameters of firefighters that should be monitored are the EKG, heart rate (HR), body temperature , blood oxygen saturation
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Luker, J.A.; Adler, L.B.; Hobaica, E.C.
1959-01-23
The purpose of this investigation was to determine the reaction characteristics of satuated mixtures of knall gas (stoichiometric mixture of hydrogen and oxygen) --steam and mixtures of heavy knall gas (stoichm-ometric mixture of deuterion and oxygen) saturated with heavy water. These mixtues were studied experimentally over composition ranges from no reaction limit to enriched compositions which supported detonations. (auth)
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Zahari, Marina; Lee, Dominic Savio; Darlow, Brian Alexander
2016-10-01
The displayed readings of Masimo pulse oximeters used in the Benefits Of Oxygen Saturation Targeting (BOOST) II and related trials in very preterm babies were influenced by trial-imposed offsets and an artefact in the calibration software. A study was undertaken to implement new algorithms that eliminate the effects of offsets and artefact. In the BOOST-New Zealand trial, oxygen saturations were averaged and stored every 10 s up to 36 weeks' post-menstrual age. Two-hundred and fifty-seven of 340 babies enrolled in the trial had at least two weeks of stored data. Oxygen saturation distribution patterns corresponding with a +3 % or -3 % offset in the 85-95 % range were identified together with that due to the calibration artefact. Algorithms involving linear and quadratic interpolations were developed, implemented on each baby of the dataset and validated using the data of a UK preterm baby, as recorded from Masimo oximeters with the original software and a non-offset Siemens oximeter. Saturation distributions obtained were compared for both groups. There were a flat region at saturations 85-87 % and a peak at 96 % from the lower saturation target oximeters, and at 93-95 and 84 % respectively from the higher saturation target oximeters. The algorithms lowered the peaks and redistributed the accumulated frequencies to the flat regions and artefact at 87-90 %. The resulting distributions were very close to those obtained from the Siemens oximeter. The artefact and offsets of the Masimo oximeter's software had been addressed to determine the true saturation readings through the use of novel algorithms. The implementation would enable New Zealand data be included in the meta-analysis of BOOST II trials, and be used in neonatal oxygen studies.
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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.
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High sensitive pulse oximeter-spectrophotometer for laser-optical dosimetry in biology and medicine
NASA Astrophysics Data System (ADS)
Asimov, M. M.; Asimov, R. M.; Rubinov, A. N.; Mamilov, S. A.; Plaksiy, Yu. S.
2006-03-01
High sensitive multi channel pulse oxymeter - spectrophotometer for control of the local tissue oxygen saturation is presented. Due to an original method of data storing and processing the accuracy of measurements 3-4 times are increased in compare with similar systems. This system is used for registration of the local changes of arterial blood saturation with oxygen under effect of low intensity laser radiation. It is shown that the photodissociation of oxyhemoglobin in cutaneous blood vessels play a dominant role in the mechanism of biostimulating and therapeutic effect of low intensity laser radiation. The results of experimental investigation in vivo the dependence of arterial oxygen blood saturation on temperature and the wavelength of laser radiation are presented. It is suggested that dosimetry for laser therapy could be base on regulation of local concentration of free oxygen in tissue.
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NASA Astrophysics Data System (ADS)
Taylor, J. R.; Lovera, C.; Whaling, P. J.; Buck, K. R.; Pane, E. F.; Barry, J. P.
2013-05-01
Anthropogenic CO2 is now reaching depths over 1000 m in the Eastern Pacific, overlapping the Oxygen Minimum Zone (OMZ). Deep-sea animals - particularly, calcifiers - are suspected to be especially sensitive to environmental acidification associated with global climate change. We have investigated the effects of hypercapnia and hypoxia on the deep-sea urchin Strongylocentrotus fragilis, during two long-term exposure experiments (1 month and 4 month) at three levels of reduced pH at in situ O2 levels of approx. 10% saturation, and also to control pH at 100% O2 saturation. During the first experiment, internal acid-base balance was investigated during a one-month exposure; results show S. fragilis has limited ability to compensate for the respiratory acidosis brought on by reduced pH, due in part to low non-bicarbonate extracellular fluid buffering capacity. During the second experiment, longer-term effects of hypercapnia and variable O2 on locomotion, feeding, growth, and gonadosomatic index (GSI) were investigated; results show significant mortality and correlation of all measured parameters with environmental acidification at pH 6.6. Transient adverse effects on locomotion and feeding were seen at pH 7.2, without compromise of growth or GSI. Based on the expected changes in ocean pH and oxygen, results suggest extinction of S. fragilis in the eastern North Pacific is unlikely. Rather, we expect a shoaling and contraction of its bathymetric range.
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Administration order of midazolam/fentanyl for moderate dental sedation.
Lobb, Douglas; Clarke, Alix; Lai, Hollis
2018-02-01
The purpose of this study is to investigate the effects of administration order when a sedative drug (midazolam) and an opioid analgesic drug (fentanyl) is applied for moderate intravenous (IV) sedation in dentistry. A retrospective chart review was conducted in one dental clinic during its transition from a midazolam-first to a fentanyl-first protocol for dental procedures requiring moderate IV sedation. Physiological parameters, drug administration times, patient recovery times, drug dosages, and patient recall and satisfaction were investigated for differences. A total of 76 charts (40 midazolam-first and 36 fentanyl-first administrations), were used in the analysis. Administering midazolam first resulted in an average 4.38 min (52%) decrease in administration times (P < 0.001), and a decrease in procedural recollection immediately following the procedure (P = 0.03), and 24 to 48 hours later (P = 0.009). Administering fentanyl first required an average of 2.43 mg (29%) less midazolam (P < 0.001). No significant differences were found for change in vital signs, minimum oxygen saturation levels, recovery times, and patient satisfaction (P > 0.05). Oxygen saturation levels did not drop below 90% for either group; however, 5 cases in the fentanyl-first group fell to between 90% and 92%, compared with 0 cases in the midazolam-first group. The administration order of fentanyl and midazolam may have different effects on patients and the sedation procedure. Findings from this study should be used to facilitate discussion among dental practitioners and to guide additional research investigating this topic.
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Yadav, Rahul; Bhutia, Ongkila; Shukla, Garima; Roychoudhury, Ajoy
2014-07-01
To evaluate the effects of distraction osteogenesis in management of obstructive sleep apnoea patients secondary to temporomandibular joints ankylosis. Fifteen patients were included in study. Preoperatively the patients were worked up for polysomnography and CT scans. Only those patients with Apnoea-hypopnoea index >15 events/h denoting moderate to severe obstructive sleep apnoea were included in the study. Distraction osteogenesis was followed with 5 days latency period in adult patients and 0 days for children. Rate of distraction was 1 mm/day for adults and 2 mm/day for children till the mandibular incisors were in reverse overjet. After 3 months post distraction assessment was done using polysomnography and CT scan. TMJ ankylosis was released by doing gap arthroplasty after distraction osteogenesis. Post distraction improvement was seen in clinical features of OSA like daytime sleepiness and snoring. Epworth sleepiness scale improved from a mean of 10.25 to 2.25. Polysomnographic analysis also showed improvement in all cases with apnoea-hypopnoea index from 57.03 to 6.67 per hour. Lowest oxygen saturation improved from 64.47% to 81.20% and average minimum oxygen saturation improved from 92.17% to 98.19%. Body mass index improved from a mean of 18.26 to 21.39 kg/m2. Distraction osteogenesis is a stable and beneficial treatment option for temporomandibular joint ankylosis patients with obstructive sleep apnoea. Copyright © 2013 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.
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Video monitoring of oxygen saturation during controlled episodes of acute hypoxia.
Addison, Paul S; Foo, David M H; Jacquel, Dominique; Borg, Ulf
2016-08-01
A method for extracting video photoplethysmographic information from an RGB video stream is tested on data acquired during a porcine model of acute hypoxia. Cardiac pulsatile information was extracted from the acquired signals and processed to determine a continuously reported oxygen saturation (SvidO2). A high degree of correlation was found to exist between the video and a reference from a pulse oximeter. The calculated mean bias and accuracy across all eight desaturation episodes were -0.03% (range: -0.21% to 0.24%) and accuracy 4.90% (range: 3.80% to 6.19%) respectively. The results support the hypothesis that oxygen saturation trending can be evaluated accurately from a video system during acute hypoxia.
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Lotliker, Aneesh A; Baliarsingh, S K; Trainer, Vera L; Wells, Mark L; Wilson, Cara; Udaya Bhaskar, T V S; Samanta, Alakes; Shahimol, S R
2018-04-01
Intense blooms of the heterotrophic dinoflagellate, green Noctiluca scintillans, have been reported annually in the Northern Arabian Sea since the early 2000s. Although not known to produce organic toxins, these blooms are still categorized as a harmful due to their association with massive fish mortalities. Recent work has attributed these blooms to the vertical expansion of the oxygen minimum zone, driven by cultural eutrophication from major coastal cities in western India. As diatoms are preferred prey of green Noctiluca scintillans, more frequent blooms of this mixotroph will likely impact the productivity of important fisheries in the region. The present study uses a satellite algorithm to determine the distribution of both diatom and green Noctiluca blooms in the Northeastern Arabian Sea from 2009 to 2016. The results from shipboard microscopy of phytoplankton community composition were used to validate the satellite estimates. The satellite algorithm showed 76% accuracy for detection of green Noctiluca and 92% for diatoms. Shipboard measurements and data from biogeochemical-Argo floats were used to assess the relationship between oxygen concentrations and green Noctiluca blooms in the Northeastern Arabian Sea. Regardless of the presence of a Noctiluca bloom, the dissolved oxygen in the photic zone was always >70% saturated, with an average oxygen saturation >90%. The variability in the relative abundance of diatoms and green Noctiluca is not correlated with changes in oxygen concentration. These findings provide no evidence that cultural eutrophication has contributed to the decadal scale shifts in plankton composition in the Northeastern Arabian Sea oceanic waters. Conversely, the climatic warming of surface waters would have intensified stratification, thereby reducing net nutrient flux to the photic zone and decreasing silicate to nitrate ratios (Si:N); both factors that could increase the competitive advantage of the mixotroph, green Noctiluca, over diatoms. If so, the decadal-scale trajectory of phytoplankton community composition in the Northeastern Arabian Sea may be a harbinger of future climate-driven change in other productive oceanic systems. Copyright © 2018 Elsevier B.V. All rights reserved.
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Progressive hypoxia decouples activity and aerobic performance of skate embryos
Di Santo, Valentina; Tran, Anna H.; Svendsen, Jon C.
2016-01-01
Although fish population size is strongly affected by survival during embryonic stages, our understanding of physiological responses to environmental stressors is based primarily on studies of post-hatch fishes. Embryonic responses to acute exposure to changes in abiotic conditions, including increase in hypoxia, could be particularly important in species exhibiting long developmental time, as embryos are unable to select a different environment behaviourally. Given that oxygen is key to metabolic processes in fishes and aquatic hypoxia is becoming more severe and frequent worldwide, organisms are expected to reduce their aerobic performance. Here, we examined the metabolic and behavioural responses of embryos of a benthic elasmobranch fish, the little skate (Leucoraja erinacea), to acute progressive hypoxia, by measuring oxygen consumption and movement (tail-beat) rates inside the egg case. Oxygen consumption rates were not significantly affected by ambient oxygen levels until reaching 45% air saturation (critical oxygen saturation, Scrit). Below Scrit, oxygen consumption rates declined rapidly, revealing an oxygen conformity response. Surprisingly, we observed a decoupling of aerobic performance and activity, as tail-beat rates increased, rather than matching the declining metabolic rates, at air saturation levels of 55% and below. These results suggest a significantly divergent response at the physiological and behavioural levels. While skate embryos depressed their metabolic rates in response to progressive hypoxia, they increased water circulation inside the egg case, presumably to restore normoxic conditions, until activity ceased abruptly around 9.8% air saturation. PMID:27293746
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Progressive hypoxia decouples activity and aerobic performance of skate embryos.
Di Santo, Valentina; Tran, Anna H; Svendsen, Jon C
2016-01-01
Although fish population size is strongly affected by survival during embryonic stages, our understanding of physiological responses to environmental stressors is based primarily on studies of post-hatch fishes. Embryonic responses to acute exposure to changes in abiotic conditions, including increase in hypoxia, could be particularly important in species exhibiting long developmental time, as embryos are unable to select a different environment behaviourally. Given that oxygen is key to metabolic processes in fishes and aquatic hypoxia is becoming more severe and frequent worldwide, organisms are expected to reduce their aerobic performance. Here, we examined the metabolic and behavioural responses of embryos of a benthic elasmobranch fish, the little skate (Leucoraja erinacea), to acute progressive hypoxia, by measuring oxygen consumption and movement (tail-beat) rates inside the egg case. Oxygen consumption rates were not significantly affected by ambient oxygen levels until reaching 45% air saturation (critical oxygen saturation, S crit). Below S crit, oxygen consumption rates declined rapidly, revealing an oxygen conformity response. Surprisingly, we observed a decoupling of aerobic performance and activity, as tail-beat rates increased, rather than matching the declining metabolic rates, at air saturation levels of 55% and below. These results suggest a significantly divergent response at the physiological and behavioural levels. While skate embryos depressed their metabolic rates in response to progressive hypoxia, they increased water circulation inside the egg case, presumably to restore normoxic conditions, until activity ceased abruptly around 9.8% air saturation.
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Fetal oxygenation measurement using wireless near infrared spectroscopy
NASA Astrophysics Data System (ADS)
Macnab, Andrew; Shadgan, Babak; Janssen, Patricia; Rurak, Dan
2012-03-01
Background: Fetal well-being is determined in large part by how well the placenta is able to supply oxygen and nutrients, but current technology is unable to directly measure how well a placenta functions. Near-infrared spectroscopy (NIRS) utilizes optical methods to measure tissue oxygenation. This pilot project evaluated the feasibility of NIRS for fetal monitoring through the maternal abdominal wall using a sheep model. Methods: A miniature wireless 2-wavelength NIRS device was placed on the abdominal skin over the placenta of a pregnant ewe whose fetus had been chronically catheterized to allow arterial sampling for measurement of arterial oxygen saturation. The NIRS device has 3-paired light emitting diodes and a single photodiode detector; allowing measurement of an index of tissue oxygen saturation (TSI%). Fetal limb TSI% values were compared before and during fetal breathing movements. Correlation was made during these events between arterial values and placental TSI% monitored continuously in real time. Results: Serial measurements were obtained in a single experiment. The correlation between transcutaneous NIRS derived TSI% and direct arterial oxygen saturation was very high (R2=0.86). Measures of fetal limb TSI% were declined after episodes of fetal breathing (P<0.005). Conclusions: This correlation suggests that NIRS is sensitive enough to detect changes in fetal tissue oxygenation noninvasively through the maternal abdominal wall in real-time in a sheep model. NIRS data confirmed that fetal breathing movements decrease arterial oxygen saturation in fetal lambs. If validated by further study this optical methodology could be applied as means of monitoring fetal wellbeing in humans.
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Oxygen Saturation during Transport to the Recovery Room in Patients over Age Sixty.
anesthesia recovery room (PARR), has not been studied specifically in patients over 60 years of age . This study identifies alterations in oxygen saturation...during post-anesthesia transport in this age group. Specifically, this investigation quantifies the incidence of a decrease in SaO2 to 90% (defined in
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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.
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Cerebral arterial oxygen saturation measurements using a fiber-optic pulse oximeter.
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.
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2012-10-01
studies demonstrated that NIRS measurement of hemoglobin oxygen saturation in the tibial compartment provided reliable and sensitive correlation to...pressure increases with muscle damage, there is not a complete loss of tissue oxygen saturation in the tissue over the 14 hours of the protocol. In...allow greater detail of information and flexibility in the analysis of tissue oxygenation levels. Although the 7610 oximeter has not been
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Englund, Erin K; Rodgers, Zachary B; Langham, Michael C; Mohler, Emile R; Floyd, Thomas F; Wehrli, Felix W
2018-02-01
To investigate the relationship between blood flow and oxygen consumption in skeletal muscle, a technique called "Velocity and Perfusion, Intravascular Venous Oxygen saturation and T2*" (vPIVOT) is presented. vPIVOT allows the quantification of feeding artery blood flow velocity, perfusion, draining vein oxygen saturation, and muscle T2*, all at 4-s temporal resolution. Together, the measurement of blood flow and oxygen extraction can yield muscle oxygen consumption ( V˙O2) via the Fick principle. In five subjects, vPIVOT-derived results were compared with those obtained from stand-alone sequences during separate ischemia-reperfusion paradigms to investigate the presence of measurement bias. Subsequently, in 10 subjects, vPIVOT was applied to assess muscle hemodynamics and V˙O2 following a bout of dynamic plantar flexion contractions. From the ischemia-reperfusion paradigm, no significant differences were observed between data from vPIVOT and comparison sequences. After exercise, the macrovascular flow response reached a maximum 8 ± 3 s after relaxation; however, perfusion in the gastrocnemius muscle continued to rise for 101 ± 53 s. Peak V˙O2 calculated based on mass-normalized arterial blood flow or perfusion was 15.2 ± 6.7 mL O 2 /min/100 g or 6.0 ± 1.9 mL O 2 /min/100 g, respectively. vPIVOT is a new method to measure blood flow and oxygen saturation, and therefore to quantify muscle oxygen consumption. Magn Reson Med 79:846-855, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
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Krivec, Bojan; Voga, Gorazd; Podbregar, Matej
2004-05-31
Patients with massive pulmonary embolism and obstructive shock usually require hemodynamic stabilization and thrombolysis. Little is known about the optimal and proper use of volume infusion and vasoactive drugs, or about the titration of thrombolytic agents in patients with relative contraindication for such treatment. The aim of the study was to find the most rapidly changing hemodynamic variable to monitor and optimize the treatment of patients with obstructive shock following massive pulmonary embolism. Ten consecutive patients hospitalized in the medical intensive care unit in the community General Hospital with obstructive shock following massive pulmonary embolism were included in the prospective observational study. Heart rate, systolic arterial pressure, central venous pressure, mean pulmonary-artery pressure, cardiac index, total pulmonary vascular-resistance index, mixed venous oxygen saturation, and urine output were measured on admission and at 1, 2, 3, 4, 8, 12, and 16 hours. Patients were treated with urokinase through the distal port of a pulmonary-artery catheter. At 1 hour, mixed venous oxygen saturation, systolic arterial pressure and cardiac index were higher than their admission values (31+/-10 vs. 49+/-12%, p<0.0001; 86+/-12 vs. 105+/-17 mmHg, p<0.01; 1.5+/-0.4 vs. 1.9+/-0.7 L/min/m2, p<0.05; respectively), whereas heart rate, central venous pressure, mean pulmonary-artery pressure and urine output remained unchanged. Total pulmonary vascular-resistance index was lower than at admission (29+/-10 vs. 21+/-12 mmHg/L/min/m2, p<0.05). The relative change of mixed venous oxygen saturation at hour 1 was higher than the relative changes of all other studied variables (p<0.05). Serum lactate on admission and at 12 hours correlated to mixed venous oxygen saturation (r=-0.855, p<0.001). In obstructive shock after massive pulmonary embolism, mixed venous oxygen saturation changes more rapidly than other standard hemodynamic variables.
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Taenzer, Andreas H; Pyke, Joshua; Herrick, Michael D; Dodds, Thomas M; McGrath, Susan P
2014-02-01
The manual collection and charting of traditional vital signs data in inpatient populations have been shown to be inaccurate when compared with true physiologic values. This issue has not been examined with respect to oxygen saturation data despite the increased use of this measurement in systems designed to assess the risk of patient deterioration. Of particular note are the lack of available data examining the accuracy of oxygen saturation charting in a particularly vulnerable group of patients who have prolonged oxygen desaturations (mean SpO2 <90% over at least 15 minutes). In addition, no data are currently available that investigate the often suspected "wake up" effect, resulting from a nurse entering a patient's room to obtain vital signs. In this study, we compared oxygen saturation data recorded manually with data collected by an automated continuous monitoring system in 16 inpatients considered to be at high risk for deterioration (average SpO2 values <90% collected by the automated system in a 15-minute interval before a manual charting event). Data were sampled from the automatic collection system from 2 periods: over a 15-minute period that ended 5 minutes before the time of the manual data collection and charting, and over a 5-minute range before and after the time of the manual data collection and charting. Average saturations from prolonged baseline desaturations (15-minute period) were compared with both the manual and automated data sampled at the time of the nurse's visit to analyze for systematic change and to investigate the presence of an arousal effect. The manually charted data were higher than those recorded by the automated system. Manually recorded data were on average 6.5% (confidence interval, 4.0%-9.0%) higher in oxygen saturation. No significant arousal effect resulting from the nurse's visit to the patient's room was detected. In a cohort of patients with prolonged desaturations, manual recordings of SpO2 did not reflect physiologic patient state when compared with continuous automated sampling. Currently, early warning scores depend on manual vital sign recordings in many settings; the study data suggest that SpO2 ought to be added to the list of vital sign values that have been shown to be recorded inaccurately.
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Neurodevelopmental outcomes in the early CPAP and pulse oximetry trial.
Vaucher, Yvonne E; Peralta-Carcelen, Myriam; Finer, Neil N; Carlo, Waldemar A; Gantz, Marie G; Walsh, Michele C; Laptook, Abbot R; Yoder, Bradley A; Faix, Roger G; Das, Abhik; Schibler, Kurt; Rich, Wade; Newman, Nancy S; Vohr, Betty R; Yolton, Kimberly; Heyne, Roy J; Wilson-Costello, Deanne E; Evans, Patricia W; Goldstein, Ricki F; Acarregui, Michael J; Adams-Chapman, Ira; Pappas, Athina; Hintz, Susan R; Poindexter, Brenda; Dusick, Anna M; McGowan, Elisabeth C; Ehrenkranz, Richard A; Bodnar, Anna; Bauer, Charles R; Fuller, Janell; O'Shea, T Michael; Myers, Gary J; Higgins, Rosemary D
2012-12-27
Previous results from our trial of early treatment with continuous positive airway pressure (CPAP) versus early surfactant treatment in infants showed no significant difference in the outcome of death or bronchopulmonary dysplasia. A lower (vs. higher) target range of oxygen saturation was associated with a lower rate of severe retinopathy but higher mortality. We now report longer-term results from our prespecified hypotheses. Using a 2-by-2 factorial design, we randomly assigned infants born between 24 weeks 0 days and 27 weeks 6 days of gestation to early CPAP with a limited ventilation strategy or early surfactant administration and to lower or higher target ranges of oxygen saturation (85 to 89% or 91 to 95%). The primary composite outcome for the longer-term analysis was death before assessment at 18 to 22 months or neurodevelopmental impairment at 18 to 22 months of corrected age. The primary outcome was determined for 1234 of 1316 enrolled infants (93.8%); 990 of the 1058 surviving infants (93.6%) were evaluated at 18 to 22 months of corrected age. Death or neurodevelopmental impairment occurred in 27.9% of the infants in the CPAP group (173 of 621 infants), versus 29.9% of those in the surfactant group (183 of 613) (relative risk, 0.93; 95% confidence interval [CI], 0.78 to 1.10; P=0.38), and in 30.2% of the infants in the lower-oxygen-saturation group (185 of 612), versus 27.5% of those in the higher-oxygen-saturation group (171 of 622) (relative risk, 1.12; 95% CI, 0.94 to 1.32; P=0.21). Mortality was increased with the lower-oxygen-saturation target (22.1%, vs. 18.2% with the higher-oxygen-saturation target; relative risk, 1.25; 95% CI, 1.00 to 1.55; P=0.046). We found no significant differences in the composite outcome of death or neurodevelopmental impairment among extremely premature infants randomly assigned to early CPAP or early surfactant administration and to a lower or higher target range of oxygen saturation. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and the National Heart, Lung, and Blood Institute; SUPPORT ClinicalTrials.gov number, NCT00233324.).
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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.
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Pulsed near-infrared photoacoustic spectroscopy of blood
NASA Astrophysics Data System (ADS)
Laufer, Jan G.; Elwell, Clare E.; Delpy, Dave T.; Beard, Paul C.
2004-07-01
The aim of this study was to use pulsed near infrared photoacoustic spectroscopy to determine the oxygen saturation (SO2) of a saline suspension of red blood cells in vitro. The photoacoustic measurements were made in a cuvette which formed part of a larger circuit through which the red blood cell suspension was circulated. Oxygen saturation of the red blood cell suspension was altered between 2-3% to 100% in step increments using a membrane oxygenator and at each increment an independent measurement of oxygen saturation was made using a co-oximeter. An optical parametric oscillator laser system provided nanosecond excitation pulses at a number of wavelengths in the near-infrared spectrum (740-1040nm) which were incident on the cuvette. The resulting acoustic signals were detected using a broadband (15MHz) Fabry-Perot polymer film transducer. The optical transport coefficient and amplitude were determined from the acoustic signals as a function of wavelength. These data were then used to calculate the relative concentrations of oxy- and deoxyhaemoglobin, using their known specific absorption coefficients and an empirically determined wavelength dependence of optical scattering over the wavelength range investigated. From this, the oxygen saturation of the suspension was derived with an accuracy of +/-5% compared to the co-oximeter SO2 measurements.
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Optimization measurement of muscle oxygen saturation under isometric studies using FNIRS
NASA Astrophysics Data System (ADS)
Halim, A. A. A.; Laili, M. H.; Salikin, M. S.; Rusop, M.
2018-05-01
Development of functional near infrared spectroscopy (fNIRS) technologies has advanced quantification signal using multiple wavelength and detector to investigate hemodynamic response in human muscle. These non-invasive technologies have been widely used to solve the propagation of light inside the tissues including the absorption, scattering coefficient and to quantify the oxygenation level of haemoglobin and myoglobin in human muscle. The goal of this paper is to optimize the measurement of muscle oxygen saturation during isometric exercise using functional near infrared spectroscopy (fNIRS). The experiment was carried out on 15 sedentary healthy male volunteers. All volunteers are required to perform an isometric exercise at three assessment of muscular fatigue's level on flexor digitalis (FDS) muscle in the human forearm using fNIRS. The slopes of the signals have been highlighted to evaluate the muscle oxygen saturation of regional muscle fatigue. As a result, oxygen saturation slope from 10% exercise showed steeper than the first assessment at 30%-50% of fatigues level. The hemodynamic signal response showed significant value (p=0.04) at all three assessment of muscular fatigue's level which produce a p-value (p<0.05) measured by fNIRS. Thus, this highlighted parameter could be used to estimate fatigue's level of human and could open other possibilities to study muscle performance diagnosis.
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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.
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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
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Nebulized naloxone gently and effectively reverses methadone intoxication.
Mycyk, Mark B; Szyszko, Amy L; Aks, Steven E
2003-02-01
A 46-year-old woman presented to the Emergency Department with lethargy and respiratory depression after ingesting methadone. Initial oxygen saturation of 61% on room air did not improve with supplemental oxygenation. As venous access was initially unobtainable, naloxone was administered by nebulizer. Within 5 min oxygen saturation was 100% and mental status was normal. The patient did not develop severe withdrawal symptoms. Naloxone hydrochloride has been administered by various routes to treat opioid toxicity. Our report describes the successful use of nebulized naloxone for methadone toxicity.
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Technical considerations in continuous jugular venous oxygen saturation measurement.
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.
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An Eye Oximeter for Combat Casualty Care
1999-12-01
monitoring (e.g., retinitis pigmentosa , retinal detachment, macular degeneration, diabetic retinopathy, etc.). Recently, scanning laser microscopy...and UAH is generating instrumentation and scientific data suggesting that retinal vessel oxygen saturations (both arterial and venous) may be used...and developing the techniques required to accurately measure retinal large vessel oxygen saturations. As this work is being accomplished we have used
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NASA Astrophysics Data System (ADS)
Yu, Tianhao; Li, Qian; Li, Lin; Zhou, Chuanqing
2016-10-01
Accuracy of photoacoustic signal is the crux on measurement of oxygen saturation in functional photoacoustic imaging, which is influenced by factors such as defocus of laser beam, curve shape of large vessels and nonlinear saturation effect of optical absorption in biological tissues. We apply Monte Carlo model to simulate energy deposition in tissues and obtain photoacoustic signals reaching a simulated focused surface detector to investigate corresponding influence of these factors. We also apply compensation on photoacoustic imaging of in vivo cat cerebral cortex blood vessels, in which signals from different lateral positions of vessels are corrected based on simulation results. And this process on photoacoustic images can improve the smoothness and accuracy of oxygen saturation results.
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Clinical safety of 3-T brain magnetic resonance imaging in newborns.
Fumagalli, Monica; Cinnante, Claudia Maria; Calloni, Sonia Francesca; Sorrentino, Gabriele; Gorla, Ilaria; Plevani, Laura; Pesenti, Nicola; Sirgiovanni, Ida; Mosca, Fabio; Triulzi, Fabio
2018-03-29
The effects and potential hazards of brain magnetic resonance imaging (MRI) at 3 T in newborns are debated. Assess the impact of 3-T MRI in newborns on body temperature and physiological parameters. Forty-nine newborns, born preterm and at term, underwent 3-T brain MRI at term-corrected age. Rectal and skin temperature, oxygen saturation and heart rate were recorded before, during and after the scan. A statistically significant increase in skin temperature of 0.6 °C was observed at the end of the MRI scan (P<0.01). There was no significant changes in rectal temperature, heart rate or oxygen saturation. Core temperature, heart rate and oxygen saturation in newborns were not affected by 3-T brain MR scanning.
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Oxygen enhanced switching to combustion of lower rank fuels
Kobayashi, Hisashi; Bool, III, Lawrence E.; Wu, Kuang Tsai
2004-03-02
A furnace that combusts fuel, such as coal, of a given minimum energy content to obtain a stated minimum amount of energy per unit of time is enabled to combust fuel having a lower energy content, while still obtaining at least the stated minimum energy generation rate, by replacing a small amount of the combustion air fed to the furnace by oxygen. The replacement of oxygen for combustion air also provides reduction in the generation of NOx.
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A fiberoptic reflection oximeter.
Landsman, M L; Knop, N; Kwant, G; Mook, G A; Zijlstra, W G
1978-03-20
A catheter tip oximeter is described consisting of a cardiac catheter containing optical fibers, and incandescent light source, a light detection unit and a processing unit. Half of the optical fibers guide the light to the blood at the tip of the catheter, the other half the backscattered (reflected) light to the detection unit. The detection unit contains a dichroic mirror, transmitting most of the light with lambda less than 800 nm and reflecting most of the light with lambda greater than 900 nm, thus splitting the light into two beams. These pass through interference filters with nominal wavelengths of 640 and 920 nm respectively, and are focused on silicium barrier layer photocells. The photocell signals are amplified and fed into a divider giving the ratio of measuring (R640) and compensating (R920) photocell output. The relationship between log R640/R920 and oxygen saturation is represented by a slightly curved line. The relation may be linearized by subtracting a constant voltage from the divided output before taking the logarithm. The slope of the calibration line is dependent on the total haemoglobin concentration. Nonetheless an average calibration line can be used between 70 and 100% oxygen saturation. For 78 measurements of pig blood samples in this range (haemoglobin concentration between 96 and 161 g.1(-1)), the standard deviation of the difference between the fiberoptic oximeter and a Radiometer OSM1 oxygen saturation meter was 1.9% saturation, for 152 samples over the entire saturation range the standard deviation of the difference was 3.1% saturation. The influence of the flow velocity of blood on the light reflection depends on wavelength as well as on oxygen saturation. Therefore, complete compensation for the flow effect is not possible by simple means.
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NASA Astrophysics Data System (ADS)
Honeysett, Jack E.; Stride, Eleanor; Deng, Jing; Leung, Terence S.
2012-02-01
Near-infrared spectroscopy (NIRS) can provide an estimate of the mean oxygen saturation in tissue. This technique is limited by optical scattering, which reduces the spatial resolution of the measurement, and by absorption, which makes the measurement insensitive to oxygenation changes in larger deep blood vessels relative to that in the superficial tissue. Acousto-optic (AO) techniques which combine focused ultrasound (US) with diffuse light have been shown to improve the spatial resolution as a result of US-modulation of the light signal, however this technique still suffers from low signal-to-noise when detecting a signal from regions of high optical absorption. Combining an US contrast agent with this hybrid technique has been proposed to amplify an AO signal. Microbubbles are a clinical contrast agent used in diagnostic US for their ability to resonate in a sound field: in this work we also make use of their optical scattering properties (modelled using Mie theory). A perturbation Monte Carlo (pMC) model of light transport in a highly absorbing blood vessel containing microbubbles surrounded by tissue is used to calculate the AO signal detected on the top surface of the tissue. An algorithm based on the modified Beer-Lambert law is derived which expresses intravenous oxygen saturation in terms of an AO signal. This is used to determine the oxygen saturation in the blood vessel from a dual wavelength microbubble-contrast AO measurement. Applying this algorithm to the simulation data shows that the venous oxygen saturation is accurately recovered, and this measurement is robust to changes in the oxygenation of the superficial tissue layer.
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Stroncek, David F; Byrne, Karen M; Noguchi, Constance T; Schechter, Alan N; Leitman, Susan F
2004-09-01
BACKGROUND Red blood cell (RBC) components from donors with sickle cell trait (Hb AS) often occlude white blood cell (WBC) reduction filters. Techniques were investigated to successfully filter Hb AS donor blood by increasing the Hb oxygen saturation with storage bags and conditions suitable for transfusion products. Oxygenation kinetics were measured over 3 days in whole-blood units stored in standard-sized 600-mL polyvinylchloride (PVC) bags and whole-blood units divided into three equal parts and stored in standard-sized blood bags made from PVC, tri-2-(ethylhexyl)trimellitate (CLX) plastic, or Teflon. The filterability of Hb AS blood stored for 3 days was tested with whole-blood filters. Oxygen saturation levels did not increase in full whole-blood units from donors without sickle cell trait during 3 days of storage in 600-mL PVC bags. In divided Hb AS whole-blood units stored for 3 days, oxygen saturation levels increased from baseline levels of 45 to 56, 66, and 94 percent after storage in 600-mL PVC, CLX, and Teflon bags, respectively (n = 5, p < 0.02), and all components filtered completely. When full Hb AS whole-blood units from eight donors were stored for 3 days in 1.5-L CLX bags, all units filtered completely, but one had a high residual WBC count. Storage of Hb AS whole blood in large-capacity oxygen-permeable bags increases oxygen tension and allows more effective WBC reduction by filtration.
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Feasibility of absolute cerebral tissue oxygen saturation during cardiopulmonary resuscitation.
Meex, Ingrid; De Deyne, Cathy; Dens, Jo; Scheyltjens, Simon; Lathouwers, Kevin; Boer, Willem; Vundelinckx, Guy; Heylen, René; Jans, Frank
2013-03-01
Current monitoring during cardiopulmonary resuscitation (CPR) is limited to clinical observation of consciousness, breathing pattern and presence of a pulse. At the same time, the adequacy of cerebral oxygenation during CPR is critical for neurological outcome and thus survival. Cerebral oximetry, based on near-infrared spectroscopy (NIRS), provides a measure of brain oxygen saturation. Therefore, we examined the feasibility of using NIRS during CPR. Recent technologies (FORE-SIGHT™ and EQUANOX™) enable the monitoring of absolute cerebral tissue oxygen saturation (SctO2) values without the need for pre-calibration. We tested both FORE-SIGHT™ (five patients) and EQUANOX Advance™ (nine patients) technologies in the in-hospital as well as the out-of-hospital CPR setting. In this observational study, values were not utilized in any treatment protocol or therapeutic decision. An independent t-test was used for statistical analysis. Our data demonstrate the feasibility of both technologies to measure cerebral oxygen saturation during CPR. With the continuous, pulseless near-infrared wave analysis of both FORE-SIGHT™ and EQUANOX™ technology, we obtained SctO2 values in the absence of spontaneous circulation. Both technologies were able to assess the efficacy of CPR efforts: improved resuscitation efforts (improved quality of chest compressions with switch of caregivers) resulted in higher SctO2 values. Until now, the ability of CPR to provide adequate tissue oxygenation was difficult to quantify or to assess clinically due to a lack of specific technology. With both technologies, any change in hemodynamics (for example, ventricular fibrillation) results in a reciprocal change in SctO2. In some patients, a sudden drop in SctO2 was the first warning sign of reoccurring ventricular fibrillation. Both the FORE-SIGHT™ and EQUANOX™ technology allow non-invasive monitoring of the cerebral oxygen saturation during CPR. Moreover, changes in SctO2 values might be used to monitor the efficacy of CPR efforts.
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Mannitol Improves Brain Tissue Oxygenation in a Model of Diffuse Traumatic Brain Injury.
Schilte, Clotilde; Bouzat, Pierre; Millet, Anne; Boucheix, Perrine; Pernet-Gallay, Karin; Lemasson, Benjamin; Barbier, Emmanuel L; Payen, Jean-François
2015-10-01
Based on evidence supporting a potential relation between posttraumatic brain hypoxia and microcirculatory derangements with cell edema, we investigated the effects of the antiedematous agent mannitol on brain tissue oxygenation in a model of diffuse traumatic brain injury. Experimental study. Neurosciences and physiology laboratories. Adult male Wistar rats. Thirty minutes after diffuse traumatic brain injury (impact-acceleration model), rats were IV administered with either a saline solution (traumatic brain injury-saline group) or 20% mannitol (1 g/kg) (traumatic brain injury-mannitol group). Sham-saline and sham-mannitol groups received no insult. Two series of experiments were conducted 2 hours after traumatic brain injury (or equivalent) to investigate 1) the effect of mannitol on brain edema and oxygenation, using a multiparametric magnetic resonance-based approach (n = 10 rats per group) to measure the apparent diffusion coefficient, tissue oxygen saturation, mean transit time, and blood volume fraction in the cortex and caudoputamen; 2) the effect of mannitol on brain tissue PO2 and on venous oxygen saturation of the superior sagittal sinus (n = 5 rats per group); and 3) the cortical ultrastructural changes after treatment (n = 1 per group, taken from the first experiment). Compared with the sham-saline group, the traumatic brain injury-saline group had significantly lower tissue oxygen saturation, brain tissue PO2, and venous oxygen saturation of the superior sagittal sinus values concomitant with diffuse brain edema. These effects were associated with microcirculatory collapse due to astrocyte swelling. Treatment with mannitol after traumatic brain injury reversed all these effects. In the absence of traumatic brain injury, mannitol had no effect on brain oxygenation. Mean transit time and blood volume fraction were comparable between the four groups of rats. The development of posttraumatic brain edema can limit the oxygen utilization by brain tissue without evidence of brain ischemia. Our findings indicate that an antiedematous agent such as mannitol can improve brain tissue oxygenation, possibly by limiting astrocyte swelling and restoring capillary perfusion.
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Intraoperative colon mucosal oxygen saturation during aortic surgery.
Lee, Eugene S; Bass, Arie; Arko, Frank R; Heikkinen, Maarit; Harris, E John; Zarins, Christopher K; van der Starre, Pieter; Olcott, Cornelius
2006-11-01
Colonic ischemia after aortic reconstruction is a devastating complication with high mortality rates. This study evaluates whether Colon Mucosal Oxygen Saturation (CMOS) correlates with colon ischemia during aortic surgery. Aortic reconstruction was performed in 25 patients, using a spectrophotometer probe that was inserted in each patient's rectum before the surgical procedure. Continuous CMOS, buccal mucosal oxygen saturation, systemic mean arterial pressure, heart rate, pulse oximetry, and pivotal intra-operative events were collected. Endovascular aneurysm repair (EVAR) was performed in 20 and open repair in 5 patients with a mean age of 75 +/- 10 (+/-SE) years. CMOS reliably decreased in EVAR from a baseline of 56% +/- 8% to 26 +/- 17% (P < 0.0001) during infrarenal aortic balloon occlusion and femoral arterial sheath placement. CMOS similarly decreased during open repair from 56% +/- 9% to 15 +/- 19% (P < 0.0001) when the infrarenal aorta and iliac arteries were clamped. When aortic circulation was restored in both EVAR and open surgery, CMOS returned to baseline values 56.5 +/- 10% (P = 0.81). Mean recovery time in CMOS after an aortic intervention was 6.4 +/- 3.3 min. Simultaneous buccal mucosal oxygen saturation was stable (82% +/- 6%) during aortic manipulation but would fall significantly during active bleeding. There were no device related CMOS measurement complications. Intra-operative CMOS is a sensitive measure of colon ischemia where intraoperative events correlated well with changes in mucosal oxygen saturation. Transient changes demonstrate no problem. However, persistently low CMOS suggests colon ischemia, thus providing an opportunity to revascularize the inferior mesenteric artery or hypogastric arteries to prevent colon infarction.
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Samadi, Mahmood; Malaki, Majid; Ghaffari, Shamsi; Golshan Khalili, Roza
2012-01-01
Low Cardiac Output Syndrome (LCOS) contributes to postoperative morbidity and mortality. This article tries to find a predictive factor to interpret outcome after cardiac operation. In a cross-sectional study, 100 children with congenital heart disease undergoing cardiovascular surgery with cardiopulmonary bypass (CPB) without significant left-to-right shunt were selected. Arterial and central venous oxygen saturation values were measured via blood samples simultaneously obtained in 6-hr intervals for a total of 24-hr during postoperative period at hours 0, 6, 12, 18, and 24. Postoperative ventilation support (intubation period) and cardiovascular support were also obtained from the hospital records. Statistical analysis was later performed comparing the arterial-mixed venous oxygen saturation differences and durations of required ventilatory and cardiovascular support, both for the complicated and non-complicated patient groups. The data was processed with correlation Pearson and Mann-Whitney U tests in SPSS 15 software, P less than 0.05 was significant. Mortality following cardiac operation is 6% and complications may happen in 45% of the cases. The highest Arterial-mixed venous oxygen saturation difference occurred immediately post operation (up to 57%). These measures were high up to 18 hours in complicated and non-complicated groups (36% vs. 31% ; P< 0.05). This factor cannot predict prolongation of intubation period in patients (P > 0.05). Arterial-mixed venous oxygen saturation difference may be high as much as 57% or as low as 23%.These different measures, being higher up to 18 hours in complicated to non-complicated groups after 18 hours, can be related to tissue ischemia during surgery and cannot be discriminative.
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Taheri, Parvin; Abbasi, Eidan; Abdeyazdan, Zahra; Fathizadeh, Nahid
2010-01-01
Prematurity is the main cause of death in infants under one year of age and is the main reason for neonatal intensive care unit (NICU) hospitalization. The stressful environment of NICU exposes preterm infants to inappropriate stimuli. This study aimed to determine and compare the mean heart rate and oxygen saturation of premature infants before and during a designed program in NICU. In a clinical trial study (before-after intervention) on a single group, 31 hospitalized premature newborns in NICU of Al-Zahra Hospital in Isfahan were selected by simple continuous sampling method. Data were collected through interview, observation and checklist records. The data were analyzed using SPSS and descriptive and inferential statistics. Out of 31 premature infants in the study, 60% were boys and 35% were girls. The mean (standard deviation) of oxygen saturation before and during the designed program were 92.80 (2.54) and 94.22 (2.59) percent, respectively. The results of paired t test showed a significant difference between the means of oxygen saturation of the infants before and during the program (p = 0.048), but there was no significant difference between the mean of the infants' heart beat before and during the intervention. The findings showed that applying daily silence periods can greatly help to increase oxygen saturation and can improve the growth of premature infants. Therefore, by providing more facilities in clinical environments of NICU, conducting programs to reduce light and noise in these wards would be possible.
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Sové, Richard J; Drakos, Nicole E; Fraser, Graham M; Ellis, Christopher G
2018-05-25
Red blood cell oxygen saturation is an important indicator of oxygen supply to tissues in the body. Oxygen saturation can be measured by taking advantage of spectroscopic properties of hemoglobin. When this technique is applied to transmission microscopy, the calculation of saturation requires determination of incident light intensity at each pixel occupied by the red blood cell; this value is often approximated from a sequence of images as the maximum intensity over time. This method often fails when the red blood cells are moving too slowly, or if hematocrit is too large since there is not a large enough gap between the cells to accurately calculate the incident intensity value. A new method of approximating incident light intensity is proposed using digital inpainting. This novel approach estimates incident light intensity with an average percent error of approximately 3%, which exceeds the accuracy of the maximum intensity based method in most cases. The error in incident light intensity corresponds to a maximum error of approximately 2% saturation. Therefore, though this new method is computationally more demanding than the traditional technique, it can be used in cases where the maximum intensity-based method fails (e.g. stationary cells), or when higher accuracy is required. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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NASA Astrophysics Data System (ADS)
Krasnovsky, A. A., Jr.; Roumbal, Ya. V.; Ivanov, A. V.; Ambartzumian, R. V.
2006-10-01
The rates of oxygenation of the 1O 2 trap, 1,3-diphenylisobenzofuran were measured in air-saturated organic solvents and heterogeneous D 2O-sodium dodecyl sulfate dispersions upon infrared (1267 ± 4 nm) laser irradiation. The absorbance and molar absorption coefficients of oxygen corresponding to this wavelength were estimated from the observed oxygenation rates. The data suggest that 1O 2 was formed due to direct oxygen excitation without appreciable involvement of vibrationally excited solvent molecules. The minor 'pseudophase' of detergent micelles was shown to strongly enhance overall 1O 2 production in D 2O-detergent dispersions.
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Hypoxia, Monitoring, and Mitigation System
2013-11-01
on measured and predicted data. Given the beat-to-beat method in which oxygen saturation is measured via a pulse oximeter , a certain degree of...1108-12. The incidence of hypoxemia in the immediate postoperative period was determined using a pulse oximeter for continuous monitoring of...Oxygen Saturation Measured via Pulse - Oximeter TAILSS Tactical Aircrew Integrated Life Support System TUC Time of Useful Consciousness USN United
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The United States Army Medical Department Journal. October - December 2012
2012-12-01
assess effect on weight change following injury. Nutritional programs aimed at smaller meal consumption , inclusion of breakfast, making healthier...electrocardiography, blood pres- sure, oxygen saturation, end-tidal carbon dioxide, and rectal temperatures were continuously monitored for the...blood pressure, oxygen saturation, end-tidal carbon dioxide, and rectal temperatures . Body temperature was maintained greater than 36.0°C. When
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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
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Carrascón, Vanesa; Bueno, Mónica; Fernandez-Zurbano, Purificación; Ferreira, Vicente
2017-11-01
This Article addresses the study of O 2 and SO 2 consumption rates of white and rosé wines, their relationship to the initial chemical composition, and their effects on the chemical changes experienced by wine during oxidation. Eight wines were subjected to five consecutive air-saturation cycles. O 2 was monitored periodically; SO 2 , color, and antioxidant indexes were determined after each cycle, and the initial and final compositions of the wines were thoroughly determined. Wines consumed oxygen at progressively decreasing rates. In the last cycles, after a strong decrease, consistent increases of oxygen levels were seen. Oxygen consumption rates were satisfactorily modeled, being proportional to wine copper, quercetin, and kaempherol contents and negatively proportional to cinnamic acids. SO 2 consumption rates were highly diverse between wines and were positively related to free SO 2 , Mn, and pH, among others. In the last saturations, SO 2 consumption took place regardless of O 2 consumption, implying that SO 2 should reduce chemical species oxidized in previous saturations. Some volatile phenols seem to be the end point of radical-mediated oxidation of polyphenols taking place preferably in the first saturation.
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Rejmstad, Peter; Johansson, Johannes D; Haj-Hosseini, Neda; Wårdell, Karin
2017-03-01
Continuous measurement of local brain oxygen saturation (SO 2 ) can be used to monitor the status of brain trauma patients in the neurocritical care unit. Currently, micro-oxygen-electrodes are considered as the "gold standard" in measuring cerebral oxygen pressure (pO 2 ), which is closely related to SO 2 through the oxygen dissociation curve (ODC) of hemoglobin, but with the drawback of slow in response time. The present study suggests estimation of SO 2 in brain tissue using diffuse reflectance spectroscopy (DRS) for finding an analytical relation between measured spectra and the SO 2 for different blood concentrations. The P 3 diffusion approximation is used to generate a set of spectra simulating brain tissue for various levels of blood concentrations in order to estimate SO 2 . The algorithm is evaluated on optical phantoms mimicking white brain matter (blood volume of 0.5-2%) where pO 2 and temperature is controlled and on clinical data collected during brain surgery. The suggested method is capable of estimating the blood fraction and oxygen saturation changes from the spectroscopic signal and the hemoglobin absorption profile. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
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NASA Astrophysics Data System (ADS)
von Siebenthal, K.; Keel, M.; Dietz, V.; Fauchere, J. C.; Martin, X.; Wolf, Martin; Duc, G.; Bucher, H. U.
1996-10-01
Near-infrared spectrophotometry (NIRS) is a noninvasive method for measuring oxygenated and deoxygenated hemoglobin in the neonatal brain. Using oxygen as a tracer, it is possible to calculate cerebral blood flow (cbf) and hemoglobin concentration (cHbc), which corresponds to cerebral blood volume, by inducing small changes in arterial oxygen saturation. Variability of tcpO2 is considered to be associated with severe retinopathy of prematurity (ROP). A preliminary analysis without control found a 51 percent incidence of ROP in infants subjected to NIRS measurements whereas among infants who were not exposed to oxygen changes, only 29 percent developed ROP. A controlled study with matched pairs was performed. Thirty-nine premature newborns who had received NIRS recordings were matched with 39 out of 172 infants who had not received NIRS. Using this controlled study design there was no difference in the incidence and severity of ROP between the two groups. The conclusions are that: 1) small changes in oxygen saturation of 3 to 10 percent to measure cbf and cHbc did not increase the incidence or the degree of severity of ROP. 2) A controlled study design is important. Analyses of uncontrolled data would have led to the conclusion that oxygen changes as used with NIRS increase the risk of ROP.
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Vosloo, Andre; Laas, Anél; Vosloo, Dalene
2013-01-01
Marine invertebrates have evolved multiple responses to naturally variable environmental oxygen, all aimed at either maintaining cellular oxygen homeostasis or limiting cellular damage during or after hypoxic or hyperoxic events. We assessed organismal (rates of oxygen consumption and ammonia excretion) and cellular (heat shock protein expression, anti-oxidant enzymes) responses of juvenile and adult abalone exposed to low (~83% of saturation), intermediate (~95% of saturation) and high (~115% of saturation) oxygen levels for one month. Using the Comet assay, we measured DNA damage to determine whether the observed trends in the protective responses were sufficient to prevent oxidative damage to cells. Juveniles were unaffected by moderately hypoxic and hyperoxic conditions. Elevated basal rates of superoxide dismutase, glutathione peroxidase and catalase were sufficient to prevent DNA fragmentation and protein damage. Adults, with their lower basal rate of anti-oxidant enzymes, had increased DNA damage under hypoxic and hyperoxic conditions, indicating that the antioxidant enzymes were unable to prevent oxidative damage under hypoxic and hyperoxic conditions. The apparent insensitivity of juvenile abalone to decreased and increased oxygen might be related to their life history and development in algal and diatom biofilms where they are exposed to extreme diurnal fluctuations in dissolved oxygen levels. Copyright © 2012 Elsevier Inc. All rights reserved.
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Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask
NASA Technical Reports Server (NTRS)
Kelly, Mark; Pettit, Donald
2003-01-01
A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.
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Simulation of oxygen saturation measurement in a single blood vein.
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.
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Administration order of midazolam/fentanyl for moderate dental sedation
2018-01-01
Background The purpose of this study is to investigate the effects of administration order when a sedative drug (midazolam) and an opioid analgesic drug (fentanyl) is applied for moderate intravenous (IV) sedation in dentistry. Methods A retrospective chart review was conducted in one dental clinic during its transition from a midazolam-first to a fentanyl-first protocol for dental procedures requiring moderate IV sedation. Physiological parameters, drug administration times, patient recovery times, drug dosages, and patient recall and satisfaction were investigated for differences. Results A total of 76 charts (40 midazolam-first and 36 fentanyl-first administrations), were used in the analysis. Administering midazolam first resulted in an average 4.38 min (52%) decrease in administration times (P < 0.001), and a decrease in procedural recollection immediately following the procedure (P = 0.03), and 24 to 48 hours later (P = 0.009). Administering fentanyl first required an average of 2.43 mg (29%) less midazolam (P < 0.001). No significant differences were found for change in vital signs, minimum oxygen saturation levels, recovery times, and patient satisfaction (P > 0.05). Oxygen saturation levels did not drop below 90% for either group; however, 5 cases in the fentanyl-first group fell to between 90% and 92%, compared with 0 cases in the midazolam-first group. Conclusions The administration order of fentanyl and midazolam may have different effects on patients and the sedation procedure. Findings from this study should be used to facilitate discussion among dental practitioners and to guide additional research investigating this topic. PMID:29556559
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1993-03-08
affinity, which is less at low levels of hemoglobin saturation, increases markedly as fractional saturation increases. Thus, high affinity for 02 at... diphosphoglycerate (2,3-DPG), and carbon dioxide (Co 2). Since they are linked to 02 binding, they are called oxygen-linked effectors. The oxygen...hemoglobin molecule because of the negative charge of the ions. 2,3- Diphosphoglycerate is a molecule formed during the breakdown of sugar in normal human
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Sui, Wei-Wei; Ding, Hai-Bing; Yang, Gui-Peng; Lu, Xiao-Lan; Li, Wen-Juan; Sun, Li-Qun
2013-11-01
Series of laboratory incubation experiments were conducted to simulate degradation of organic matter in sediment-seawater interface in hypoxia enviroments along China coastal area. Under four different redox conditions (oxygen saturation: 100%, 50%, 25% and 0%), degradations of seveal biomarkers originated from Skeletonema costatum, a typical red tide alage along China coastal area were tracked. By analyzing concentrations of four fatty acid biomarkers [14:0, 16:0, 16:1(7) and 20:5] obtained at various sampling time, results showed that their concentrations decreased significantly after 2-3 weeks' incubation. Then, their concentrations changed very slowly or very little. However, degradation of the four fatty acids varied dramatically in different incubation systems. Fatty acids 14:0, 16:1(7) and 20:5 were degraded completely in all incubation systems after two-month incubation, but 25% to 35% of 16:0 was reserved in the systems. Based on multi-G model, degradations of the four fatty acids were quantively described. The results indicated that all four fatty acids had fast-degraded and slow-degraded fractions. Their degradation rate constants (k(av)) ranged from 0.079 to 0.84 d(-1). The fastest degradation of 14:0 and 16:1 (7) occurred under 25% oxygen concentrations. For these two compounds, in the fastest degradation system, their k(av), values were 2.3 folds and 1.7 folds higher than those in the slowest degradation system [50% oxygen saturation for 14:0 and 100% oxygen saturation for 16:1(7)] respectively. The 16:0 was degraded fastest under the anoxic condition and slowest under the 50% oxygen saturation. The ratio of the two k(av)s was 2.1. The k(av)s of 20:5 had a positive relationship with oxygen saturations. Results of this study suggested that besides oxgen saturations, structure and features of organic compounds, roles of microbe in the envrioments and etc. might affect degradations of fatty acids in S. costatum in hypoxia sediment-seawater interface along China coastal area.
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Goldberg, M S; Giannetti, N; Burnett, R T; Mayo, N E; Valois, M-F; Brophy, J M
2008-10-01
Recent studies suggest that persons with congestive heart failure (CHF) may be at higher risk for short-term effects of air pollution. This daily diary panel study in Montreal, Quebec, was carried out to determine whether oxygen saturation and pulse rate were associated with selected personal factors, weather conditions and air pollution. Thirty-one subjects with CHF participated in this study in 2002 and 2003. Over a 2-month period, the investigators measured their oxygen saturation, pulse rate, weight and temperature each morning and recorded these and other data in a daily diary. Air pollution and weather conditions were obtained from fixed-site monitoring stations. The study made use of mixed regression models, adjusting for within-subject serial correlation and temporal trends, to determine the association between oxygen saturation and pulse rate and personal and environmental variables. Depending on the model, we accounted for the effects of a variety of personal variables (eg, body temperature, salt consumption) as well as nitrogen dioxide (NO2), ozone, maximum temperature and change in barometric pressure at 8:00 from the previous day. In multivariable analyses, the study found that oxygen saturation was reduced when subjects reported that they were ill, consumed salt, or drank liquids on the previous day and had higher body temperatures on the concurrent day (only the latter was statistically significant). Relative humidity and decreased atmospheric pressure from the previous day were associated with oxygen saturation. In univariate analyses, there was negative associations with concentrations of fine particulates, ozone, and sulphur dioxide (SO2), but only SO2 was significant after adjustment for the effects of weather. For pulse rate, no associations were found for the personal variables and in univariate analyses the study found positive associations with NO(2), fine particulates (aerodynamic diameter of 2.5 microm or under, PM(2.5)), SO2, and maximum temperature, although only the latter two were significant after adjustment for environmental effects. The findings from the present investigation suggest that personal and environmental conditions affect intermediate physiological parameters that may affect the health of CHF patients.
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Weiss, Harvey R; Grayson, Jeremy; Liu, Xia; Barsoum, Sylviana; Shah, Harsh; Chi, Oak Z
2013-09-01
After cerebral vessel blockage, local blood flow and O2 consumption becomes lower and oxygen extraction increases. With reperfusion, blood flow is partially restored. We examined the effects of ischemia-reperfusion on the heterogeneity of local venous oxygen saturation in rats in order to determine the pattern of microregional O2 supply/consumption balance in reperfusion. The middle cerebral artery was blocked for 1 hour using the internal carotid approach in 1 group (n=9) and was then reperfused for 2 hours in another group (n=9) of isoflurane-anesthetized rats. Regional cerebral blood flow was determined using a C(14)-iodoantipyrine autoradiographic technique. Regional small vessel arterial and venous oxygen saturations were determined microspectrophotometrically. After 1 hour of ischemia, local cerebral blood flow (92±10 versus 50±10 mL/min per 100 g) and O2 consumption (4.5±0.6 versus 2.7±0.5 mL O2/min per 100 g) decreased compared with the contralateral cortex. Oxygen extraction increased (4.7±0.2 versus 5.4±0.3 mL O2/100 mL) and the variation in small vein (20-60 μm) O2 saturation as determined by its coefficient of variation (=100×SD/mean) increased (5.5 versus 10.5). With 2 hours of reperfusion, the blood flow decrement was reduced and O2 consumption returned to the value in the contralateral cortex. Oxygen extraction remained elevated in the ischemic-reperfused area and the coefficient of variation of small vein O2 saturation increased further (17.3). These data indicated continued reduction of O2 supply/consumption balance with reperfusion. They also demonstrated many small regions of low oxygenation within the reperfused cortical region.
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Effects of natural and human-induced hypoxia on coastal benthos
NASA Astrophysics Data System (ADS)
Levin, L. A.; Ekau, W.; Gooday, A. J.; Jorissen, F.; Middelburg, J. J.; Naqvi, S. W. A.; Neira, C.; Rabalais, N. N.; Zhang, J.
2009-10-01
Coastal hypoxia (defined here as <1.42 ml L-1; 62.5 μM; 2 mg L-1, approx. 30% oxygen saturation) develops seasonally in many estuaries, fjords, and along open coasts as a result of natural upwelling or from anthropogenic eutrophication induced by riverine nutrient inputs. Permanent hypoxia occurs naturally in some isolated seas and marine basins as well as in open slope oxygen minimum zones. Responses of benthos to hypoxia depend on the duration, predictability, and intensity of oxygen depletion and on whether H2S is formed. Under suboxic conditions, large mats of filamentous sulfide oxidizing bacteria cover the seabed and consume sulfide. They are hypothesized to provide a detoxified microhabitat for eukaryotic benthic communities. Calcareous foraminiferans and nematodes are particularly tolerant of low oxygen concentrations and may attain high densities and dominance, often in association with microbial mats. When oxygen is sufficient to support metazoans, small, soft-bodied invertebrates (typically annelids), often with short generation times and elaborate branchial structures, predominate. Large taxa are more sensitive than small taxa to hypoxia. Crustaceans and echinoderms are typically more sensitive to hypoxia, with lower oxygen thresholds, than annelids, sipunculans, molluscs and cnidarians. Mobile fish and shellfish will migrate away from low-oxygen areas. Within a species, early life stages may be more subject to oxygen stress than older life stages. Hypoxia alters both the structure and function of benthic communities, but effects may differ with regional hypoxia history. Human-caused hypoxia is generally linked to eutrophication, and occurs adjacent to watersheds with large populations or agricultural activities. Many occurrences are seasonal, within estuaries, fjords or enclosed seas of the North Atlantic and the NW Pacific Oceans. Benthic faunal responses, elicited at oxygen levels below 2 ml L-1, typically involve avoidance or mortality of large species and elevated abundances of enrichment opportunists, sometimes prior to population crashes. Areas of low oxygen persist seasonally or continuously beneath upwelling regions, associated with the upper parts of oxygen minimum zones (SE Pacific, W Africa, N Indian Ocean). These have a distribution largely distinct from eutrophic areas and support a resident fauna that is adapted to survive and reproduce at oxygen concentrations <0.5 ml L-1. Under both natural and eutrophication-caused hypoxia there is loss of diversity, through attrition of intolerant species and elevated dominance, as well as reductions in body size. These shifts in species composition and diversity yield altered trophic structure, energy flow pathways, and corresponding ecosystem services such as production, organic matter cycling and organic C burial. Increasingly the influences of nature and humans interact to generate or exacerbate hypoxia. A warmer ocean is more stratified, holds less oxygen, and may experience greater advection of oxygen-poor source waters, making new regions subject to hypoxia. Future understanding of benthic responses to hypoxia must be established in the context of global climate change and other human influences such as overfishing, pollution, disease, habitat loss, and species invasions.
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Skoczylas, Michał; Laudański, Tadeusz
2003-10-01
Cardiotocography has become the standard for fetal monitoring in labor. False-positive findings during electronic fetal heart rate monitoring may were not associated with neonatal acidemia. Because of the poor specificity of fetal heart rate monitoring in predicting fetal distress, new methods are being investigated as a way to improve the accuracy of assessing the infant's condition during labor. The aim of this study was to determinate the efficiency of fetal blood oxygen saturation (FSpO2) and computer analysis of the fetal heart rate (Co-CTG) in the late 1-st stage of labor as a prognostic factor of newborn acidemia. Total 62 subjects were studied. During labors and deliveries fetal oxygen saturation was continuously recorded, with use of Nellecor N-400 fetal pulse oximeter and continous CTG were performed by Hewlett Packard 50A. Transdermal fetal oxygen saturation measurements and CTG results obtained during the labors was analyzed using MONAKO system (ITAM Zabrze). The results were compared with the values of pH and base deficit in the umbilical artery measured just after delivery. The sensitivity, specificity, negative, positive predictive values and Youden factor based on FHR and FSpO2, for prognosis of neonatal acidosis were: 65%, 80%, 16%, 97.5% 60% and 0.135 respectively FHR; and 100%, 60%, 100%, 96.8% and 0.968 respectively FSpO2. 1. The examination of fetal blood oxygen saturation in the labor is a useful prognostic factor of the newborn outcome. 2. The best predictive value for intrapartum fetal asphyxia with metabolic acidosis was found when fetal pulse oximetry is added to cardiotocography.
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The effect of autoimmune retinopathy on retinal vessel oxygen saturation.
Waizel, Maria; Türksever, Cengiz; Todorova, Margarita G
2018-05-22
To study the retinal vessel oxygen saturation alterations in patients with autoimmune retinopathy (AIR) and patients with autoimmune retinopathy associated with retinitis pigmentosa (AIR-RP) in comparison with healthy controls and patients with isolated retinitis pigmentosa (RP). Prospective, cross-sectional, and non-interventional study. Retinal vessel oximetry (RO) was performed on a total of 139 eyes: six eyes suffering from AIR and four eyes with AIR-RP were compared to 59 healthy control eyes and to 70 eyes with RP. A computer-based program of the retinal vessel analyser unit (IMEDOS Systems UG, Jena, Germany) was used to evaluate retinal vessel oxygen saturation. The mean oxygen saturation in the first and second branch retinal arterioles (A-SO 2 ) and venules (V-SO 2 ) were measured and their difference (A-V SO 2 ) was calculated. In addition, we measured the diameter of the retinal arterioles (D-A) and venules (D-V). Oxygen metabolism is altered in patients with isolated AIR and AIR-RP. Both, AIR and AIR-RP groups, differed from healthy controls showing significantly higher V-SO 2 values and significantly lower A-V SO 2 values (p < 0.025). In addition, the AIR-RP group could be differentiated from eyes suffering from isolated RP by means of significantly higher V-SO 2 values. Comparing retinal vessel diameters, both, the AIR and AIR-RP groups, presented with significant arterial (p = 0.05) and venular (p < 0.03) vessel attenuation than the healthy control group. Based on our results, in analogy to patients suffering from RP, oxygen metabolism seems to be altered in AIR patients.
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Influence of low oxygen tensions and sorption to sediment black carbon on biodegradation of pyrene.
Ortega-Calvo, José-Julio; Gschwend, Philip M
2010-07-01
Sorption to sediment black carbon (BC) may limit the aerobic biodegradation of polycyclic aromatic hydrocarbons (PAHs) in resuspension events and intact sediment beds. We examined this hypothesis experimentally under conditions that were realistic in terms of oxygen concentrations and BC content. A new method, based on synchronous fluorescence observations of (14)C-pyrene, was developed for continuously measuring the uptake of dissolved pyrene by Mycobacterium gilvum VM552, a representative degrader of PAHs. The effect of oxygen and pyrene concentrations on pyrene uptake followed Michaelis-Menten kinetics, resulting in a dissolved oxygen half-saturation constant (K(om)) of 14.1 microM and a dissolved pyrene half-saturation constant (K(pm)) of 6 nM. The fluorescence of (14)C-pyrene in air-saturated suspensions of sediments and induced cells followed time courses that reflected simultaneous desorption and biodegradation of pyrene, ultimately causing a quasi-steady-state concentration of dissolved pyrene balancing desorptive inputs and biodegradation removals. The increasing concentrations of (14)CO(2) in these suspensions, as determined with liquid scintillation, evidenced the strong impact of sorption to BC-rich sediments on the biodegradation rate. Using the best-fit parameter values, we integrated oxygen and sorption effects and showed that oxygen tensions far below saturation levels in water are sufficient to enable significant decreases in the steady-state concentrations of aqueous-phase pyrene. These findings may be relevant for bioaccumulation scenarios that consider the effect of sediment resuspension events on exposure to water column and sediment pore water, as well as the direct uptake of PAHs from sediments.
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NASA Astrophysics Data System (ADS)
Shaharin, Alfi; Krite Svanberg, Emilie; Ellerström, Ida; Subash, Arman Ahamed; Khoptyar, Dmitry; Andersson-Engels, Stefan; Åkeson, Jonas
2013-11-01
Muscle tissue saturation (StO2) has been measured with two non-invasive optical techniques and the results were compared. One of the techniques is widely used in the hospitals - the CW-NIRS technique. The other is the photon timeof- flight spectrometer (pTOFS) developed in the Group of Biophotonics, Lund University, Sweden. The wavelengths used in both the techniques are 730 nm and 810 nm. A campaign was arranged to perform measurements on 21 (17 were taken for comparison) healthy adult volunteers (8 women and 13 men). Oxygen saturations were measured at the right lower arm of each volunteer. To observe the effects of different provocations on the oxygen saturation a blood pressure cuff was attached in the upper right arm. For CW-NIRS, the tissue saturation values were in the range from 70-90%, while for pTOFS the values were in the range from 55-60%.
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Stevenson, Ryan A; Schlesinger, Joseph J; Wallace, Mark T
2013-02-01
Anesthesiology requires performing visually oriented procedures while monitoring auditory information about a patient's vital signs. A concern in operating room environments is the amount of competing information and the effects that divided attention has on patient monitoring, such as detecting auditory changes in arterial oxygen saturation via pulse oximetry. The authors measured the impact of visual attentional load and auditory background noise on the ability of anesthesia residents to monitor the pulse oximeter auditory display in a laboratory setting. Accuracies and response times were recorded reflecting anesthesiologists' abilities to detect changes in oxygen saturation across three levels of visual attention in quiet and with noise. Results show that visual attentional load substantially affects the ability to detect changes in oxygen saturation concentrations conveyed by auditory cues signaling 99 and 98% saturation. These effects are compounded by auditory noise, up to a 17% decline in performance. These deficits are seen in the ability to accurately detect a change in oxygen saturation and in speed of response. Most anesthesia accidents are initiated by small errors that cascade into serious events. Lack of monitor vigilance and inattention are two of the more commonly cited factors. Reducing such errors is thus a priority for improving patient safety. Specifically, efforts to reduce distractors and decrease background noise should be considered during induction and emergence, periods of especially high risk, when anesthesiologists has to attend to many tasks and are thus susceptible to error.
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Roubinian, Nareg; Elliott, C Gregory; Barnett, Christopher F; Blanc, Paul D; Chen, Joan; De Marco, Teresa; Chen, Hubert
2012-10-01
Limited data are available on the effects of air travel in patients with pulmonary hypertension (PH), despite their risk of physiologic compromise. We sought to quantify the incidence and severity of hypoxemia experienced by people with PH during commercial air travel. We recruited 34 participants for a prospective observational study during which cabin pressure, oxygen saturation (Sp O 2 ), heart rate, and symptoms were documented serially at multiple predefined time points throughout commercial flights. Oxygen desaturation was defined as SpO2, <85%. Median flight duration was 3.6 h (range, 1.0-7.3 h). Mean ± SD cabin pressure at cruising altitude was equivalent to the pressure 1,968 ± 371 m (6,456 ± 1,218 ft) above sea level (ASL)(maximum altitude 5 2,621 m [8,600 ft] ASL). Median change in Sp O 2 from sea level to cruising altitude was 2 4.9% (range, 2.0% to 2 15.8%). Nine subjects (26% [95% CI, 12%-38%]) experienced oxygen desaturation during flight (minimum Sp O 2 5 74%). Thirteen subjects (38%) reported symptoms during flight, of whom five also experienced desaturations. Oxygen desaturation was associated with cabin pressures equivalent to . 1,829 m (6,000 ft) ASL, ambulation, and flight duration(all P values , .05). Hypoxemia is common among people with PH traveling by air, occurring in one in four people studied. Hypoxemia was associated with lower cabin pressures, ambulation during flight, and longer flight duration. Patients with PH who will be traveling on flights of longer duration or who have a history of oxygen use, including nocturnal use only, should be evaluated for supplemental in-flight oxygen.
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Effects of skin pigmentation on pulse oximeter accuracy at low saturation.
Bickler, Philip E; Feiner, John R; Severinghaus, John W
2005-04-01
It is uncertain whether skin pigmentation affects pulse oximeter accuracy at low HbO2 saturation. The accuracy of finger pulse oximeters during stable, plateau levels of arterial oxygen saturation (Sao2) between 60 and 100% were evaluated in 11 subjects with darkly pigmented skin and in 10 with light skin pigmentation. Oximeters tested were the Nellcor N-595 with the OxiMax-A probe (Nellcor Inc., Pleasanton, CA), the Novametrix 513 (Novametrix Inc., Wallingford, CT), and the Nonin Onyx (Nonin Inc., Plymouth, MN). Semisupine subjects breathed air-nitrogen-carbon dioxide mixtures through a mouthpiece. A computer used end-tidal oxygen and carbon dioxide concentrations determined by mass spectrometry to estimate breath-by-breath Sao2, from which an operator adjusted inspired gas to rapidly achieve 2- to 3-min stable plateaus of desaturation. Comparisons of oxygen saturation measured by pulse oximetry (Spo2) with Sao2 (by Radiometer OSM3) were used in a multivariate model to determine the interrelation between saturation, skin pigmentation, and oximeter bias (Spo2 - Sao2). At 60-70% Sao2, Spo2 (mean of three oximeters) overestimated Sao2 (bias +/- SD) by 3.56 +/- 2.45% (n = 29) in darkly pigmented subjects, compared with 0.37 +/- 3.20% (n = 58) in lightly pigmented subjects (P < 0.0001). The SD of bias was not greater with dark than light skin. The dark-light skin differences at 60-70% Sao2 were 2.35% (Nonin), 3.38% (Novametrix), and 4.30% (Nellcor). Skin pigment-related differences were significant with Nonin below 70% Sao2, with Novametrix below 90%, and with Nellcor at all ranges. Pigment-related bias increased approximately in proportion to desaturation. The three tested pulse oximeters overestimated arterial oxygen saturation during hypoxia in dark-skinned individuals.
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Palotie, Tuula; Riekki, Siru; Mäkitie, Antti; Bachour, Adel; Arte, Sirpa; Bäck, Leif
2017-10-01
Our aim was to evaluate the effect of mandible advancement splint (MAS) in mild, moderate, and severe obstructive sleep apnea (OSA). We also determined, if and in which OSA-groups the adequate forward movement in MAS could be quantified without sleep registration for different OSA levels. A retrospective study. The effect of MAS was measured with clinical methods and by sleep registration. The series consisted of 103 patients, 75 males and 28 females (mean age 52 years) suffering from mild (32 per cent), moderate (32 per cent), or severe (36 per cent) OSA, who were treated with MAS at Helsinki University Hospital, Finland during the years 2011-2012. Seventy per cent of the patients had tried continuous positive airway pressure (CPAP) before MAS. The lower the body mass index (BMI) was the bigger the probability was to get apnea/hypopnea index (AHI) values <5 per hour with MAS (P < 0.01). The total AHI decreased significantly from the baseline with MAS: 23 per hour (range 5-89) to 6 per hour (range 0.3-54), (P < 0.001). The mean oxygen desaturation index (ODI4%) improved significantly from 16 per hour (range 1-76) to 5.3 per hour (range 0.2-49), (P < 0.01), and the minimum oxygen saturation improved significantly from 84 per cent (67-91) to 87 per cent (68-93), (P < 0.01). The reduction of AHI with MAS was significantly bigger in patients with a previous CPAP experience (73 per cent) than those who did not tried CPAP therapy. The positive correlation was found between the decrease in AHI and the increase of the protrusion in MAS. Both sleep recordings and subjective indicators demonstrated that MAS therapy was successful in OSA based on ESS, total AHI, ODI4%, and minimum oxygen saturation values. It seems useful to increase the protrusion at its maximal clinical tolerance. An experienced dentist could make therapeutically decision concerning the follow up of MAS efficacy regardless of the result of sleep study. We suggest that MAS is a valuable treatment alternative for CPAP. However, the previous use of CPAP with MAS as well as lower baseline BMI seem to have a positive correlation with the success of MAS therapy. © The Author 2016. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com
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[Design of a pulse oximeter used to low perfusion and low oxygen saturation].
Tan, Shuangping; Ai, Zhiguang; Yang, Yuxing; Xie, Qingguo
2013-05-01
This paper presents a new pulse oximeter used to low perfusion at 0.125% and wide oxygen saturation range from 35% to 100%. In order to acquire the best PPG signals, the variable gain amplifier(VGA) is adopted in hardware. The self-developed auto-correlation modeling method is adopted in software and it can extract pulse wave from low perfusion signals and remove motion artifacts partly.
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Optical diagnosis of testicular torsion: feasibility and methodology
NASA Astrophysics Data System (ADS)
Shadgan, Babak; Macnab, Andrew; Stothers, Lynn; Kajbafzadeh, A. M.
2014-03-01
Background: Torsion of the testis compromises blood flow through the spermatic cord; testicular ischemia results which if not diagnosed promptly and corrected surgically irrevocably damages the testis. Current diagnostic modalities aimed at rationalizing surgical exploration by demonstrating interruption of spermatic cord blood flow or testicular ischemia have limited applicability. Near infrared spectroscopy (NIRS) offers a non-invasive optical method for detection of ischemia; continuous wave and frequency domain devices have been used experimentally; no device customized for clinical use has been designed. Methods: A miniature spatially resolved NIRS device with light emitting diode light source was applied over the right and left spermatic cord and the difference in oxygen saturation between the two sides measured. Results: In a 14-month old boy with a history of unilateral testicular pain color Doppler ultrasonography was equivocal but the NIRS-derived tissue oxygen saturation index (TSI) was significantly reduced on the left side. Confirmation of torsion of the left testicle was made surgically. Conclusions: Spatially resolved NIRS monitoring of spermatic cord oxygen saturation is feasible in children, adding to prior studies of testicular oxygen saturation in adults. Customized device design and further clinical trials would enhance the applicability of NIRS as a diagnostic entity for torsion.
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Evaluation of peripheral perfusion in term newborns before and after Yintang (EX-HN 3) massage.
Tugcu, Ali Ulas; Cabioglu, Tugrul; Abbasoglu, Aslihan; Ecevit, Ayse; Ince, Deniz Anuk; Tarcan, Aylin
2015-12-01
To identify how acupressure on the acupoint Yintang (EX-HN 3) impacts oxygen saturation, pulse rate, and peripheral perfusion in term-born infants without underlying disease. Infants born between weeks 37 and 42 of gestation were included in this study. The polyclinic's neonatology room was noise-controlled and made half-dark to prevent the perfusion index from being confounded. A pulse oximeter was linked to the baby's left lower extremity. Acupressure was applied on Yintang (EX-HN 3) for 30 s clockwise, held for 30 s, and then acupressure was applied for another 30 s counterclockwise. The baby's SaO2, pulse rate, and perfusion index were recorded for each minute before and after acupressure. When pre- and post-acupressure pulse rate values were compared, a significant decrease in pulse rate values after acupressure application was observed. When pre- and post-acupressure oxygen saturation values were compared, a significant increase in post-acupressure oxygen saturation was observed. In addition, peripheral perfusion increased significantly after acupressure. Acupressure application has been used in traditional medicine for many years. However, it is not yet widely used in modern medicine. This study shows the impact of acupressure on neonatal skin perfusion, oxygen saturation, and pulse rate.
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Oxygen saturation profile in healthy preterm infants.
Harigopal, S; Satish, H P; Taktak, A F G; Southern, K W; Shaw, N J
2011-09-01
To establish a reference range for oxygen saturation (SpO(2)) in well preterm infants to guide home oxygen therapy using a pulse oximeter and Pulse Oximetry Data Analysis Software (PODS). SpO(2) and heart-rate profiles of healthy preterm infants receiving mechanical ventilation for less than 6 h and supplemental oxygen for less than 48 h were monitored using a pulse oximeter. The stored data were downloaded from the monitor to a personal computer as individual files. Each infant's files of SpO(2) were subsequently displayed in graphic form, and a reference range was constructed using dedicated software, PODS. 43 infants were studied. The median value of all infants mean SpO(2) values was 95% (range 92-99%). The median duration of saturations less than 85% and between 85% and 90 % were 1% and 2% respectively. Using the study group median, 5th and 95th percentiles, a cumulative frequency curve of time against SpO(2) value was constructed (representing the reference range of SpO(2) profiles in healthy preterm infants). The SpO(2) reference range can be used as an easy and practical guide to compare SpO(2) profiles of infants on home oxygen therapy and guide their oxygen therapy.
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Osinga, Ronald; Derksen-Hooijberg, Marlous; Wijgerde, Tim; Verreth, Johan A J
2017-06-15
Rates of dark respiration and net photosynthesis were measured for six replicate clonal fragments of the stony coral Galaxea fascicularis (Linnaeus 1767), which were incubated under 12 different combinations of dissolved oxygen (20%, 100% and 150% saturation), dissolved carbon dioxide (9.5 and 19.1 µmol l -1 ) and water flow (1-1.6 versus 4-13 cm s -1 ) in a repeated measures design. Dark respiration was enhanced by increased flow and increased oxygen saturation in an interactive way, which relates to improved oxygen influx into the coral tissue. Oxygen saturation did not influence net photosynthesis: neither hypoxia nor hyperoxia affected net photosynthesis, irrespective of flow and pH, which suggests that hyperoxia does not induce high rates of photorespiration in this coral. Flow and pH had a synergistic effect on net photosynthesis: at high flow, a decrease in pH stimulated net photosynthesis by 14%. These results indicate that for this individual of G. fascicularis , increased uptake of carbon dioxide rather than increased efflux of oxygen explains the beneficial effect of water flow on photosynthesis. Rates of net photosynthesis measured in this study are among the highest ever recorded for scleractinian corals and confirm a strong scope for growth. © 2017. Published by The Company of Biologists Ltd.
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Wireless Monitoring of Liver Hemodynamics In Vivo
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
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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.
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Hypoxia and lost gills: respiratory ecology of a temperate larval damselfly.
Sesterhenn, Timothy M; Reardon, Erin E; Chapman, Lauren J
2013-01-01
Damselfly larvae, important predators and prey in many freshwater communities, may be particularly sensitive to hypoxia because their caudal lamellae (external gills) are frequently lost. In this study, we address how lost lamellae interact with low oxygen to affect respiration and behavior of the widespread North American damselfly Ischnura posita. Results showed no effect of lost lamellae on resting metabolic rate or critical oxygen tension. Ventilation behaviors increased only when dissolved oxygen (DO) was at or below 25% saturation and these behaviors were not affected by the number of lamellae. Use of the oxygen-rich surface layer occurred almost exclusively at the lowest dissolved oxygen level tested (10% saturation, 2.0 kPa). Damselflies that were missing lamellae spent more time at the surface than individuals with intact lamellae. The negative relationship between body size and time at the surface, and the negative relationship between body mass and critical oxygen tension suggest that larger I. posita may be more hypoxia tolerant than smaller individuals. Overall, I. posita was minimally affected by missing lamellae and seems well-adapted to low DO habitats. Average critical oxygen tension was very low (0.48 kPa, 2.4% saturation), suggesting that individuals can maintain their metabolic rate across a broad range of DO, and behaviors changed only at DO levels below the hypoxia tolerance thresholds of many other aquatic organisms. Copyright © 2012 Elsevier Ltd. All rights reserved.
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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).
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Lenkin, Andrey I; Zaharov, Viktor I; Lenkin, Pavel I; Smetkin, Alexey A; Bjertnaes, Lars J; Kirov, Mikhail Y
2013-05-01
In cardiac surgery, the choice of temperature regimen during cardiopulmonary bypass (CPB) remains a subject of debate. Hypothermia reduces tissue metabolic demands, but may impair the autoregulation of cerebral blood flow and contribute to neurological morbidity. The aim of this study was to evaluate the effect of two different temperature regimens during CPB on the systemic oxygen transport and the cerebral oxygenation during surgical correction of acquired heart diseases. In a prospective study, we randomized 40 adult patients with combined valvular disorders requiring surgical correction of two or more valves into two groups: (i) a normothermic (NMTH) group (n = 20), in which the body core temperature was maintained at 36.6°C during CPB and (ii) a hypothermic (HPTH) group (n = 20), in which the body was cooled to a core temperature of 32°C maintained throughout the period of CPB. The systemic oxygen transport and the cerebral oxygen saturation (SctO2) were assessed by means of a PiCCO2 haemodynamic monitor and a cerebral oximeter, respectively. All the patients received standard perioperative monitoring. We assessed haemodynamic and oxygen transport parameters, the duration of mechanical ventilation and the length of the ICU and the hospital stays. During CPB, central venous oxygen saturation was significantly higher in the HPTH group but SctO2 was increased in the NMTH group (P < 0.05). Cardiac index, systemic oxygen delivery and consumption increased postoperatively in both groups. However, oxygen delivery and consumption were significantly higher in the NMTH group (P < 0.05). The duration of respiratory support and the length of ICU and hospital stays did not differ between the groups. During combined valve surgery, normothermic CPB provides lower central venous oxygen saturation, but increases cerebral tissue oxygenation when compared with the hypothermic regimen.
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NASA Astrophysics Data System (ADS)
Ibey, Bennett; Subramanian, Hariharan; Ericson, Nance; Xu, Weijian; Wilson, Mark; Cote, Gerard L.
2005-03-01
A blood perfusion and oxygenation sensor has been developed for in situ monitoring of transplanted organs. In processing in situ data, motion artifacts due to increased perfusion can create invalid oxygenation saturation values. In order to remove the unwanted artifacts from the pulsatile signal, adaptive filtering was employed using a third wavelength source centered at 810nm as a reference signal. The 810 nm source resides approximately at the isosbestic point in the hemoglobin absorption curve where the absorbance of light is nearly equal for oxygenated and deoxygenated hemoglobin. Using an autocorrelation based algorithm oxygenation saturation values can be obtained without the need for large sampling data sets allowing for near real-time processing. This technique has been shown to be more reliable than traditional techniques and proven to adequately improve the measurement of oxygenation values in varying perfusion states.
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NASA Astrophysics Data System (ADS)
Dent, Paul; Tun, Sai Han; Fillioe, Seth; Deng, Bin; Satalin, Josh; Nieman, Gary; Wilcox, Kailyn; Searles, Quinn; Narsipur, Sri; Peterson, Charles M.; Goodisman, Jerry; Mostrom, James; Steinmann, Richard; Chaiken, J.
2018-02-01
We previously reported a new algorithm "PV[O]H" for continuous, noninvasive, in vivo monitoring of hematocrit changes in blood and have since shown its utility for monitoring in humans during 1) hemodialysis, 2) orthostatic perturbations and 3) during blood loss and fluid replacement in a rat model. We now show that the algorithm is sensitive to changes in hemoglobin oxygen saturation. We document the phenomenology of the effect and explain the effect using new results obtained from humans and rat models. The oxygen sensitivity derives from the differential absorption of autofluorescence originating in the static tissues by oxy and deoxy hemoglobin. Using this approach we show how to perform simultaneous, noninvasive, in vivo, continuous monitoring of hematocrit, vascular volume, hemoglobin oxygen saturation, pulse rate and breathing rate in mammals using a single light source. We suspect that monitoring of changes in this suite of vital signs can be provided with improved time response, sensitivity and precision compared to existing methodologies. Initial results also offer a more detailed glimpse into the systemic oxygen transport in the circulatory system of humans.
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NASA Astrophysics Data System (ADS)
Sujatha, N.; Anand, B. S. Suresh; Nivetha, K. Bala; Narayanamurthy, V. B.; Seshadri, V.; Poddar, R.
2015-07-01
Light-based diagnostic techniques provide a minimally invasive way for selective biomarker estimation when tissues transform from a normal to a malignant state. Spectroscopic techniques based on diffuse reflectance characterize the changes in tissue hemoglobin/oxygenation levels during the tissue transformation process. Recent clinical investigations have shown that changes in tissue oxygenation and microcirculation are observed in diabetic subjects in the initial and progressive stages. In this pilot study, we discuss the potential of diffuse reflectance spectroscopy (DRS) in the visible (Vis) range to differentiate the skin microcirculatory hemoglobin levels between normal and advanced diabetic subjects with and without neuropathy. Average concentration of hemoglobin as well as hemoglobin oxygen saturation within the probed tissue volume is estimated for a total of four different sites in the foot sole. The results indicate a statistically significant decrease in average total hemoglobin and increase in hemoglobin oxygen saturation levels for diabetic foot compared with a normal foot. The present study demonstrates the ability of reflectance spectroscopy in the Vis range to determine and differentiate the changes in tissue hemoglobin and hemoglobin oxygen saturation levels in normal and diabetic subjects.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Podberezskaya, N. V., E-mail: podberez@niic.nsc.ru; Bolotina, N. B., E-mail: nb-bolotina@mail.ru; Komarov, V. Yu., E-mail: komarov-v-y@niic.nsc.ru
Hexagonal YBaCo{sub 4}O{sub 7} crystals (sp. gr. P6{sub 3}mc, a{sub h} = 6.3058(4) Å, c{sub h} = 10.2442(7) Å, Z = 2) are saturated with oxygen to the YBaCo{sub 4}O{sub 8.4} composition and studied by X-ray diffraction (XRD) analysis. The saturation is completed by a structural first-order phase transition to orthorhombic crystals (sp. gr. Pbc2{sub 1}, a{sub o} = 31.8419(2) Å, b{sub o} = 10.9239(5) Å, c{sub o} = 10.0960(5) Å, Z = 20). The connection of two lattices is expressed in terms of the action of matrix (500/120/001) on the hexagonal basis. Five structural fragments of the same typemore » but with different degrees of order alternate along the long axis of the oxygen-saturated orthorhombic structure. The XRD data on single crystals differ from the results obtained by other researchers on ceramic samples; possible causes of these differences are discussed.« less
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NASA Astrophysics Data System (ADS)
Singh, Suraj Kumar; Husain, Sajid; Kumar, Ankit; Chaudhary, Sujeet
2018-02-01
Polycrystalline Fe3O4 thin films were grown on Si(100) substrate by reactive DC sputtering at different oxygen partial pressures PO2 for controlling the growth associated density of antiphase boundaries (APBs). The micro-Raman analyses were performed to study the structural and electronic properties in these films. The growth linked changes in the APBs density are probed by electron-phonon coupling strength (λ) and isothermal magnetization measurements. The estimated values of λ are found to vary from 0.39 to 0.56 with the increase in PO2 from 2.2 × 10-5 to 3.0 × 10-5 Torr, respectively. The saturation magnetization (saturation field) values are found to increase (decrease) from 394 (5.9) to 439 (3.0) emu/cm3 (kOe) with the increase in PO2 . The sharp Verwey transition (∼120 K), low saturation field, high saturation magnetization and low value of λ (comparable to the bulk value ∼0.51) clearly affirm the negligible amount of APBs in the high oxygen partial pressure deposited thin films.
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Wong, David T; Yee, Amanda J; Leong, Siaw May; Chung, Frances
2017-04-01
During the process of tracheal intubation, patients are apneic or hypoventilating and are at risk of becoming hypoxemic. This risk is especially high in patients with acute or chronic respiratory failure and accompanying compromised respiratory reserve. To address this concern, apneic oxygenation can be administered during tracheal intubation to aid in maintaining arterial oxygen saturation. The objective of this narrative review is to examine the utilization of apneic oxygenation within the operating room, intensive care unit (ICU), emergency department, and pre-hospital settings and to determine its efficacy compared with controls. For this narrative review, we obtained pertinent articles using MEDLINE ® (1946 to April 2016), EMBASE™ (1974 to April 2016), Google Scholar, and manual searches. Apneic oxygenation was administered using various techniques, including the use of nasal prongs, nasopharyngeal or endotracheal catheters, or laryngoscopes. First, all 12 operating room studies showed that apneic oxygenation significantly prolonged the duration to, and incidence of, desaturation. Second, two of the five ICU studies showed a significantly smaller decline in oxygen saturation with apneic oxygenation, with three studies showing no statistically significant difference vs controls. Lastly, two emergency department or pre-hospital studies showed that the use of apneic oxygenation resulted in a significantly lower incidence of desaturation and smaller declines in oxygen saturation. Sixteen of the 19 studies showed that apneic oxygenation prolongs safe apneic time and reduces the incidence of arterial oxygen desaturation. Overall, studies in this review show that apneic oxygenation prolongs the time to oxygen desaturation during tracheal intubation. Nevertheless, the majority of the studies were small in size, and they neither measured nor were adequately powered to detect adverse respiratory events or other serious rare complications. Prolonged apneic oxygenation (with its consequent hypercarbia) can have risks and should be avoided in patients with conditions such as increased intracranial pressure, metabolic acidosis, hyperkalemia, and pulmonary hypertension.
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USDA-ARS?s Scientific Manuscript database
Atlantic salmon fry were stocked into twelve circular 0.5 m3 tanks in a flow-through system and exposed to either high (1.5-2 body-lengths per second, or BL/s) or low (less than 0.5 BL/s) swimming speeding and high (100% saturation) or low (70% saturation) dissolved oxygen (DO) while being raised fr...
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Mebius, Mirthe J; du Marchie Sarvaas, Gideon J; Wolthuis, Diana W; Bartelds, Beatrijs; Kneyber, Martin C J; Bos, Arend F; Kooi, Elisabeth M W
2017-03-16
Some infants with congenital heart disease are at risk of in-hospital cardiac arrest. To better foresee cardiac arrest in infants with congenital heart disease, it might be useful to continuously assess end-organ perfusion. Near-infrared spectroscopy is a non-invasive method to continuously assess multisite regional tissue oxygen saturation. We report on two infants with duct-dependent congenital heart disease who demonstrated a gradual change in cerebral and/or renal tissue oxygen saturation before cardiopulmonary resuscitation was required. In both cases, other clinical parameters such as heart rate, arterial oxygen saturation and blood pressure did not indicate that deterioration was imminent. These two cases demonstrate that near-infrared spectroscopy might contribute to detecting a deteriorating clinical condition and might therefore be helpful in averting cardiopulmonary collapse and need for resuscitation in infants with congenital heart disease.
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Burrai, Francesco; Micheluzzi, Valentina; Bugani, Valentina
2014-01-01
Few randomized controlled trial studies have focused on the effect of music in cancer patients, and there are no randomized controlled trials on the effects of live music with saxophone in cancer patients. To determine the effects of live saxophone music on various physiological parameters, pain level, and mood level. A randomized controlled trial study. 52 cancer patients were randomized to a control group (n = 26), an experimental group (n = 26) whose members received 30 minutes of live music therapy with saxophone. Systolic and diastolic blood pressure, pulse rate, glycemia, oxygen saturation, pain level, and mood level were measured before and after the live music performance. There was a statistical difference between the groups for oxygen saturation (0.003) and mood level (0.001). Live music performed with a saxophone could be introduced in oncology care to improve the oxygen saturation and mood in cancer patients.
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Deng, Ke-wu; Zhou, Yu-jie; Xu, Xi-qi; Wu, Ming-ying; Wang, Guo-hong; Bian, Hong; Chen, Bo; Wang, Chun-bo
2012-10-01
To summary the efficacy and safety of aerosolized iloprost in patients with pulmonary hypertensive crisis. On the basis of conventional therapy, aerosolized iloprost (10 µg per time for 10 - 15 min in 2 hours interval, 8 times per day) was administered to four patients with idiopathic pulmonary arterial hypertension and pulmonary hypertensive crisis. Blood pressure, heart rate, systemic artery oxygen saturation, systolic pulmonary arterial pressure (sPAP) measured by echocardiography and the adverse events were analyzed. After aerosolized iloprost therapy, sPAP was significantly decreased and systemic artery oxygen saturation was improved. Adverse events (nausea, vomiting, diarrhea, dry cough) were observed in two patients, and the iloprost use was stopped in one patient due to severe vomiting and diarrhea. Aerosolized iloprost could significantly reduce the sPAP and improve the systemic artery oxygen saturation in patients with pulmonary hypertension crisis.
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Oxygen requirement of separated hybrid catfish eggs
USDA-ARS?s Scientific Manuscript database
Channel catfish egg masses require hatchery water with over 7.8 ppm dissolved oxygen at 80° F (95% air saturation) to maintain maximum oxygen consumption as they near hatching. This concentration is called the critical oxygen requirement by scientists but for the purpose of this article we will call...
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Performance of a continuous flow passenger oxygen mask at an altitude of 40,000 feet.
DOT National Transportation Integrated Search
1996-02-01
A redesigned continuous flow passenger oxygen mask was tested for its ability to deliver an adequate supply of oxygen at an altitude of 40,000 feet above sea level. Four male subjects participated in the study. Blood oxygen saturation (SaO2) baseline...
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Early Oxygen-Utilization and Brain Activity in Preterm Infants
de Vries, Linda S.; Groenendaal, Floris; Toet, Mona C.; Lemmers, Petra M. A.; Vosse van de, Renè E.; van Bel, Frank; Benders, Manon J. N. L.
2015-01-01
The combined monitoring of oxygen supply and delivery using Near-InfraRed spectroscopy (NIRS) and cerebral activity using amplitude-integrated EEG (aEEG) could yield new insights into brain metabolism and detect potentially vulnerable conditions soon after birth. The relationship between NIRS and quantitative aEEG/EEG parameters has not yet been investigated. Our aim was to study the association between oxygen utilization during the first 6 h after birth and simultaneously continuously monitored brain activity measured by aEEG/EEG. Forty-four hemodynamically stable babies with a GA < 28 weeks, with good quality NIRS and aEEG/EEG data available and who did not receive morphine were included in the study. aEEG and NIRS monitoring started at NICU admission. The relation between regional cerebral oxygen saturation (rScO2) and cerebral fractional tissue oxygen extraction (cFTOE), and quantitative measurements of brain activity such as number of spontaneous activity transients (SAT) per minute (SAT rate), the interval in seconds (i.e. time) between SATs (ISI) and the minimum amplitude of the EEG in μV (min aEEG) were evaluated. rScO2 was negatively associated with SAT rate (β=-3.45 [CI=-5.76- -1.15], p=0.004) and positively associated with ISI (β=1.45 [CI=0.44-2.45], p=0.006). cFTOE was positively associated with SAT rate (β=0.034 [CI=0.009-0.059], p=0.008) and negatively associated with ISI (β=-0.015 [CI=-0.026- -0.004], p=0.007). Oxygen delivery and utilization, as indicated by rScO2 and cFTOE, are directly related to functional brain activity, expressed by SAT rate and ISI during the first hours after birth, showing an increase in oxygen extraction in preterm infants with increased early electro-cerebral activity. NIRS monitored oxygenation may be a useful biomarker of brain vulnerability in high-risk infants. PMID:25965343
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Test-retest reliability of retinal oxygen saturation measurement.
O'Connell, Rachael A; Anderson, Andrew J; Hosking, Sarah L; Batcha, Abrez H; Bui, Bang V
2014-06-01
To determine intrasession and intersession repeatability of retinal vessel oxygen saturation from the Oxymap Retinal Oximeter using a whole image-based analysis technique and so determine optimal analysis parameters to reduce variability. Ten fundus oximetry images were acquired through dilated pupils from 18 healthy participants (aged 22 to 38) using the Oxymap Retinal Oximeter T1. A further 10 images were obtained 1 to 2 weeks later from each individual. Analysis was undertaken for subsets of images to determine the number of images needed to return a stable coefficient of variation (CoV). Intrasession and intersession variability were quantified by evaluating the CoV and establishing the 95% limits of agreement using Bland and Altman analysis. Retinal oxygenation was derived from the distribution of oxygenation values from all vessels of a given width in an image or set of images, as described by Paul et al. in 2013. Grouped in 10-μm-wide bins, oxygen saturation varied significantly for both arteries and veins (p < 0.01). Between 110 and 150 μm, arteries had the least variability between individuals, with average CoVs less than 5% whose confidence intervals did not overlap with the greater than 10% average CoVs for veins across the same range. Bland and Altman analysis showed that there was no bias within or between recording sessions and that the 95% limits of agreement were generally lower in arteries. Retinal vessel oxygen saturation measurements show variability within and between clinical sessions when the whole image is used, which we believe more accurately reflects the true variability in Oxymap images than previous studies on select image segments. Averaging data from vessels 100 to 150 μm in width may help to minimize such variability.
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Kawadler, Jamie M; Kirkham, Fenella J; Clayden, Jonathan D; Hollocks, Matthew J; Seymour, Emma L; Edey, Rosanna; Telfer, Paul; Robins, Andrew; Wilkey, Olu; Barker, Simon; Cox, Tim C S; Clark, Chris A
2015-07-01
Sickle cell anemia is associated with compromised oxygen-carrying capability of hemoglobin and a high incidence of overt and silent stroke. However, in children with no evidence of cerebral infarction, there are changes in brain morphometry relative to healthy controls, which may be related to chronic anemia and oxygen desaturation. A whole-brain tract-based spatial statistics analysis was carried out in 25 children with sickle cell anemia with no evidence of abnormality on T2-weighted magnetic resonance imaging (13 male, age range: 8-18 years) and 14 age- and race-matched controls (7 male, age range: 10-19 years) to determine the extent of white matter injury. The hypotheses that white matter damage is related to daytime peripheral oxygen saturation and steady-state hemoglobin were tested. Fractional anisotropy was found to be significantly lower in patients in the subcortical white matter (corticospinal tract and cerebellum), whereas mean diffusivity and radial diffusivity were higher in patients in widespread areas. There was a significant negative relationship between radial diffusivity and oxygen saturation (P<0.05) in the anterior corpus callosum and a trend-level negative relationship between radial diffusivity and hemoglobin (P<0.1) in the midbody of the corpus callosum. These data show widespread white matter abnormalities in a sample of asymptomatic children with sickle cell anemia, and provides for the first time direct evidence of a relationship between brain microstructure and markers of disease severity (eg, peripheral oxygen saturation and steady-state hemoglobin). This study suggests that diffusion tensor imaging metrics may serve as a biomarker for future trials of reducing hypoxic exposure. © 2015 American Heart Association, Inc.
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[Nocturnal hypoxemia and arrhythmia in patients with chronic obstructive lung diseases (COLD)].
Skwarski, K
1989-05-01
A decrease in the arterial blood saturation by oxygen in patients with POChP is a frequent phenomenon. It is more serious in patients type blue boaters and less frequent among patients type pink puffers. The aim of the paper was to compare the arterial blood saturation by oxygen in the groups examined during two nights: during the first night the patients breathed atmospheric air whereas during the second night they were given oxygen. The author also studied the influence of oxygenation of an organism on the frequency of cardiac rhythm disorders (ZRS). The author examined a group of 20 patients with the predominance of chronic bronchitis--blue boaters (average VC was 1.95 l, FEV1--0.81 l, PaO2 while breathing atmospheric air 52 mm Hg and 68 mm Hg after giving oxygen, PaCO2 47 and 51 mm Hg respectively) and 20 patients with the predominance of emphysema--pink puffers (average VC--2.30 l, FEV1--0.86 l, PaO2 while breathing atmospheric air 60 mm Hg and 70 mm Hg after giving oxygen, PaCO2 39 and 40 mm respectively). It was found that the patients with heavy hypoxaemia and hypercapnia had worse arterial blood saturation by oxygen during the two nights of investigation in comparison with the other group. The author also found more frequent cardiac rhythm disorders in this group of patients. Giving oxygen improved blood oxygenation in the two groups and lowered the frequency of cardiac rhythm disorders. The results obtained indicate to the need of oxygen therapy in patients with advanced POChP, especially during the night so as to avoid nocturnal hypoxaemia of an organism.
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On improving the speed and reliability of T2-Relaxation-Under-Spin-Tagging (TRUST) MRI
Xu, Feng; Uh, Jinsoo; Liu, Peiying; Lu, Hanzhang
2011-01-01
A T2-Relaxation-Under-Spin-Tagging (TRUST) technique was recently developed to estimate cerebral blood oxygenation, providing potentials for non-invasive assessment of the brain's oxygen consumption. A limitation of the current sequence is the need for long TR, as shorter TR causes an over-estimation in blood R2. The present study proposes a post-saturation TRUST by placing a non-selective 90° pulse after the signal acquisition to reset magnetization in the whole brain. This scheme was found to eliminate estimation bias at a slight cost of precision. To improve the precision, TE of the sequence was optimized and it was found that a modest TE shortening of 3.4ms can reduce the estimation error by 49%. We recommend the use of post-saturation TRUST sequence with a TR of 3000ms and a TE of 3.6ms, which allows the determination of global venous oxygenation with scan duration of 1 minute 12 seconds and an estimation precision of ±1% (in units of oxygen saturation percentage). PMID:22127845
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Safety in the use of compressed air versus oxygen for the ophthalmic patient.
Rodgers, Laura A; Kulwicki, Anahid
2002-02-01
Oxygen, routinely administered during surgery to avoid hypoxia, poses risks including increased likelihood of surgical room fires and predisposition to retinal phototoxicity in patients. Compressed air to supplement ventilation may be safer than oxygen. The purpose of this study was to determine whether hypoxia occurs more frequently when compressed air replaces supplemental oxygen during ophthalmic surgery. A convenience sample of 111 patients was randomly assigned to receive supplemental oxygen (group 1) or compressed air (group 2). Patients with serious cardiac or pulmonary disease were excluded. Blood oxygen levels were monitored during surgery by pulse oximetry. Oxygen was administered to all group 2 patients whose oxygen saturation fell to less than 90% or by more than 5% below baseline. No differences were observed between groups in age, ASA classification, type of surgery, or anesthetic drugs or doses. Minor, but statistically higher oxygen values were observed in group 1. The frequency with which oxygen saturation decreased below 90% or below 5% of baseline was similar in both groups. Supplemental oxygen is not required routinely in selected patients undergoing ophthalmic surgery. By using compressed air, the risk of operating room fires and retinal phototoxicity may be reduced.
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Robust optode-based method for measuring in situ oxygen profiles in gravelly streambeds.
Vieweg, Michael; Trauth, Nico; Fleckenstein, Jan H; Schmidt, Christian
2013-09-03
One of the key environmental conditions controlling biogeochemical reactions in aquatic sediments like streambeds is the distribution of dissolved oxygen. We present a novel approach for the in situ measurement of vertical oxygen profiles using a planar luminescence-based optical sensor. The instrument consists of a transparent acrylic tube with the oxygen-sensitive layer mounted on the outside. The luminescence is excited and detected by a moveable piston inside the acrylic tube. Since no moving parts are in contact with the streambed, the disturbance of the subsurface flow field is minimized. The precision of the distributed oxygen sensor (DOS) was assessed by a comparison with spot optodes. Although the precision of the DOS, expressed as standard deviation of calculated oxygen air saturation, is lower (0.2-6.2%) compared to spot optodes (<0.1-0.6%), variations of the oxygen content along the profile can be resolved. The uncertainty of the calculated oxygen is assessed with a Monte Carlo uncertainty assessment. The obtained vertical oxygen profiles of 40 cm in length reveal variations of the oxygen content reaching from 90% to 0% air saturation and are characterized by patches of low oxygen rather than a continuous decrease with depth.
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Oxygen desaturation during the six-minute walk test in COPD patients*
Moreira, Maria Ângela Fontoura; de Medeiros, Gabriel Arriola; Boeno, Francesco Pinto; Sanches, Paulo Roberto Stefani; da Silva, Danton Pereira; Müller, André Frotta
2014-01-01
Objective: To evaluate the behavior of oxygen saturation curves throughout the six-minute walk test (6MWT) in patients with COPD. Methods: We included 85 patients, all of whom underwent spirometry and were classified as having moderate COPD (modCOPD, n = 30) or severe COPD (sevCOPD, n = 55). All of the patients performed a 6MWT, in a 27-m corridor with continuous SpO2 and HR monitoring by telemetry. We studied the SpO2 curves in order to determine the time to a 4% decrease in SpO2, the time to the minimum SpO2 (Tmin), and the post-6MWT time to return to the initial SpO2, the last designated recovery time (RT). For each of those curves, we calculated the slope. Results: The mean age in the modCOPD and sevCOPD groups was 66 ± 10 years and 62 ± 11 years, respectively. At baseline, SpO2 was > 94% in all of the patients; none received supplemental oxygen during the 6MWT; and none of the tests were interrupted. The six-minute walk distance did not differ significantly between the groups. The SpO2 values were lowest in the sevCOPD group. There was no difference between the groups regarding RT. In 71% and 63% of the sevCOPD and modCOPD group patients, respectively, a ≥ 4% decrease in SpO2 occurred within the first minute. We found that FEV1% correlated significantly with the ΔSpO2 (r = −0.398; p < 0.001), Tmin (r = −0.449; p < 0.001), and minimum SpO2 (r = 0.356; p < 0.005). Conclusions: In the sevCOPD group, in comparison with the modCOPD group, SpO2 was lower and the Tmin was greater, suggesting a worse prognosis in the former. PMID:25029644
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Collett, T.S.; Wendlandt, R.F.
2000-01-01
The analyses of downhole log data from Ocean Drilling Program (ODP) boreholes on the Blake Ridge at Sites 994, 995, and 997 indicate that the Schlumberger geochemical logging tool (GLT) may yield useful gas hydrate reservoir data. In neutron spectroscopy downhole logging, each element has a characteristic gamma ray that is emitted from a given neutron-element interaction. Specific elements can be identified by their characteristic gamma-ray signature, with the intensity of emission related to the atomic elemental concentration. By combining elemental yields from neutron spectroscopy logs, reservoir parameters including porosities, lithologies, formation fluid salinities, and hydrocarbon saturations (including gas hydrate) can be calculated. Carbon and oxygen elemental data from the GLT was used to determine gas hydrate saturations at all three sites (Sites 994, 995, and 997) drilled on the Blake Ridge during Leg 164. Detailed analyses of the carbon and oxygen content of various sediments and formation fluids were used to construct specialized carbon/oxygen ratio (COR) fan charts for a series of hypothetical gas hydrate accumulations. For more complex geologic systems, a modified version of the standard three-component COR hydrocarbon saturation equation was developed and used to calculate gas hydrate saturations on the Blake Ridge. The COR-calculated gas hydrate saturations (ranging from about 2% to 14% bulk volume gas hydrate) from the Blake Ridge compare favorably to the gas hydrate saturations derived from electrical resistivity log measurements.
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NASA Astrophysics Data System (ADS)
Schmidt, M.; Eggert, A.
2016-02-01
The Angola Gyre and the Northern Benguela Upwelling System are two major oxygen minimum zones (OMZ) of different kind connected by the system of African Eastern Boundary Currents. We discuss results from a 3-dimensional coupled biogeochemical model covering both oxygen-deficient systems. The biogeochemical model component comprises trophic levels up to zooplankton. Physiological properties of organisms are parameterized from field data gained mainly in the course of the project "Geochemistry and Ecology of the Namibian Upwelling System" (GENUS). The challenge of the modelling effort is the different nature of both systems. The Angola Gyre, located in a "shadow zone" of the tropical Atlantic, has a low productivity and little ventilation, hence a long residence time of water masses. In the northern Benguela Upwelling System, trade winds drive an intermittent, but permanent nutrient supply into the euphotic zone which fuels a high coastal productivity, large particle export and high oxygen consumption from dissimilatory processes. In addition to the local processes, oxygen-deficient water formed in the Angola Gyre is one of the source water masses of the poleward undercurrent, which feeds oxygen depleted water into the Benguela system. In order to simulate the oxygen distribution in the Benguela system, both physical transport as well as local biological processes need to be carefully adjusted in the model. The focus of the analysis is on the time scale and the relative contribution of the different oxygen related processes to the oxygen budgets in both the oxygen minimum zones. Although these are very different in both the OMZ, the model is found as suitable to produce oxygen minimum zones comparable with observations in the Benguela and the Angola Gyre as well. Variability of the oxygen concentration in the Angola Gyre depends strongly on organismic oxygen consumption, whereas the variability of the oxygen concentration on the Namibian shelf is governed mostly by pole-ward advection of tropical water masses.
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2014-01-01
Background Mild hypoxia is common in stroke patients and may have significant adverse effects on the ischemic brain after stroke. The use of oxygen treatment is rapidly increasing in European stroke units but is not without side effects. It impedes early mobilization, could pose an infection risk, and may encourage the formation of toxic free radicals, leading to further damage to the ischemic brain. In the Stroke Oxygen Pilot Study (2 or 3 L/min for 72 hours) neurological recovery at one week was better in the oxygen group than in controls, and after correction for difference in baseline stroke severity and prognostic factors, there was a trend to better outcome with oxygen at six months. Oxygen was as effective in mild as in severe strokes. Oxygen saturation is lower at night than during the day, and episodes of oxygen desaturation are common during sleep. Nocturnal oxygen supplementation is likely to reduce the burden of hypoxia without interfering with daytime mobilization and rehabilitation. Before wider use of oxygen supplementation becomes established it is important to obtain better evidence on which patients benefit from such treatment. Methods Participants will be randomized to one of three groups: the first will receive continuous oxygen for 72 hours (at a rate of 2 or 3 L/min depending on baseline oxygen saturation), the second group will receive nocturnal oxygen only (at a rate of 2 or 3 L/min depending on baseline oxygen saturation) and the third group will not receive any oxygen (control). A baseline assessment is performed at randomization and a one-week follow-up completed. Outcome data at three, six and twelve months will be obtained via a questionnaire sent to the patient by the trial center. Discussion This study will provide evidence on the effectiveness of oxygen supplementation for the treatment of stroke and whether nocturnal oxygen is a potentially beneficial therapy regimen. Trial registration This trial is registered with the ISRCTN register ID number ISRCTN52416964 PMID:24684940
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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.
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Retinopathy of prematurity and the oxygen conundrum: lessons learned from recent randomized trials.
Fleck, Brian W; Stenson, Ben J
2013-06-01
Emerging data from randomised controlled trials of different pulse oximeter oxygen saturation (SpO(2)) target ranges shows that higher SpO(2) targets are associated with a higher risk of severe retinopathy of prematurity. However, the trials have also shown that higher SpO(2) targets are associated with improved survival. In the light of these results and pending the full results for long-term outcome, it is recommended that oxygen saturation targets for preterm infants of gestational age less than 28 weeks at birth should be maintained at or more than 90%. Copyright © 2013 Elsevier Inc. All rights reserved.
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The measurement of hemoglobin oxygen saturation using multiwavelength photoacoustic microscopy
NASA Astrophysics Data System (ADS)
Deng, Zilin; Yang, Xiaoquan; Yu, Lejun; Gong, Hui
2010-02-01
Hemoglobin oxygen saturation (SO2) is one of the most critical functional parameters to the metabolism. In this paper, we mainly introduced some initial results of measuring blood oxygen using multi-wavelength photoacoustic microscopy (PAM). In phantom study, we demonstrate the photoacoustic signal amplitude increases linearly with the concentration of red or blue ink. Then the calculated concentration of red ink in double-ink mixtures with PAM has a 5% difference with the result measured with spectrophotometric analysis. In ex vivo experiment, the measured result exhibt 15% difference between the PAM and spectrophotometric analysis. Experiment results suggest that PAM could be used to determine the SO2 quantitatively.
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New method of extracting information of arterial oxygen saturation based on ∑ | 𝚫 |
NASA Astrophysics Data System (ADS)
Dai, Wenting; Lin, Ling; Li, Gang
2017-04-01
Noninvasive detection of oxygen saturation with near-infrared spectroscopy has been widely used in clinics. In order to further enhance its detection precision and reliability, this paper proposes a method of time domain absolute difference summation (∑|Δ|) based on a dynamic spectrum. In this method, the ratio of absolute differences between intervals of two differential sampling points at the same moment on logarithm photoplethysmography signals of red and infrared light was obtained in turn, and then they obtained a ratio sequence which was screened with a statistical method. Finally, use the summation of the screened ratio sequence as the oxygen saturation coefficient Q. We collected 120 reference samples of SpO2 and then compared the result of two methods, which are ∑|Δ| and peak-peak. Average root-mean-square errors of the two methods were 3.02% and 6.80%, respectively, in the 20 cases which were selected randomly. In addition, the average variance of Q of the 10 samples, which were obtained by the new method, reduced to 22.77% of that obtained by the peak-peak method. Comparing with the commercial product, the new method makes the results more accurate. Theoretical and experimental analysis indicates that the application of the ∑|Δ| method could enhance the precision and reliability of oxygen saturation detection in real time.
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New method of extracting information of arterial oxygen saturation based on ∑|𝚫 |
NASA Astrophysics Data System (ADS)
Wenting, Dai; Ling, Lin; Gang, Li
2017-04-01
Noninvasive detection of oxygen saturation with near-infrared spectroscopy has been widely used in clinics. In order to further enhance its detection precision and reliability, this paper proposes a method of time domain absolute difference summation (∑|Δ|) based on a dynamic spectrum. In this method, the ratio of absolute differences between intervals of two differential sampling points at the same moment on logarithm photoplethysmography signals of red and infrared light was obtained in turn, and then they obtained a ratio sequence which was screened with a statistical method. Finally, use the summation of the screened ratio sequence as the oxygen saturation coefficient Q. We collected 120 reference samples of SpO2 and then compared the result of two methods, which are ∑|Δ| and peak-peak. Average root-mean-square errors of the two methods were 3.02% and 6.80%, respectively, in the 20 cases which were selected randomly. In addition, the average variance of Q of the 10 samples, which were obtained by the new method, reduced to 22.77% of that obtained by the peak-peak method. Comparing with the commercial product, the new method makes the results more accurate. Theoretical and experimental analysis indicates that the application of the ∑|Δ| method could enhance the precision and reliability of oxygen saturation detection in real time.
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Comparison between deep breathing exercises and incentive spirometry after CABG surgery.
Renault, Julia Alencar; Costa-Val, Ricardo; Rosseti, Márcia Braz; Houri Neto, Miguel
2009-01-01
To compare the effects of deep breathing exercises (DBE) and the flow-oriented incentive spirometry (IS) in patients undergone coronary artery bypass grafting (CABG) through the following variables: forced vital capacity - FVC, forced expiratory volume in 1 second - FEV(1), maximal respiratory pressures and oxygen saturation. Thirty six patients in CABG postoperative period underwent thirty minutes of non-invasive ventilation during the first 24 hours after extubation and were randomly shared into two groups as following: DBE (n=18) and IS (n=18). The spirometric variables were assessed on the preoperative period and seventh postoperative day (POD). The respiratory muscle strength and oxygen saturation were assessed on the preoperative period, first, second and seventh POD. The groups were considered homogeneous in relation to the demographic and surgical variables. It has been noted fall in the values of FVC and FEV(1) between the preoperative period and the seventh POD, but without significant differences between groups. The maximal respiratory pressures showed drop in the first POD but with and partial recovery until the seventh POD, also without significant differences between groups. The oxygen saturation was the only variable that was completely recovered on the seventh POD, also without significant differences between groups. There were not observed significant differences in maximal respiratory pressures, spirometric variables and oxygen saturation in patients undergone deep breathing exercises and flow-oriented incentive spirometry after coronary artery bypass grafting.
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Bohnhorst, B; Seidel, K; Böhne, C; Peter, C; Pirr, S
2018-06-21
This study compiled percentiles for cardiorespiratory parameters in healthy term neonates during quiet sleep. We enrolled 215 healthy term neonates born at Hannover Medical School, Germany, between October 2011 and March 2013. They were prospectively observed on the maternity ward at a median age of two days using six-hour recordings of pulse oximeter plethysmography, oxygen saturation, thoracic breathing movements and electrocardiogram during sleep in a supine position. We examined their heart rate, respiratory rate and oxygen saturation during quiet sleep, plus bradycardias, apnoeas lasting at least four seconds and desaturations below 85%. The third, 50 th and 97 th percentiles were calculated as follows: heart rate 87, 112 and 133 beats per minute, respiratory rate 32, 44 and 57 per minute and oxygen saturation 94, 98 and 100%. Desaturations, apnoeas and bradycardias below 80 beats per minute were common and recorded in 54%, 98% and 30% of participants. In contrast, only 7% experienced bradycardias of less than two-thirds of the baseline heart rate and 5% experienced apnoeas exceeding 15 seconds. Our results will facilitate the evidence-based valuation of cardiorespiratory parameters in term neonates and help to validate the significance of cardiorespiratory events in preterm infants at discharge. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
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Viljoen, Andre; Byth, Karen; Coombs, Malcolm; Mahoney, Greg; Stewart, Douglas
2011-01-01
The death of a patient under sedation in New South Wales, Australia, in 2002 has again raised the question of the safety of dental sedation. This study sought answers to 2 questions: Can safe oxygen saturation levels (≥94%) be consistently maintained by a single operator/sedationist? Does the additional use of propofol, in subanesthetic doses, increase the risk of exposure to hypoxemia? Three thousand five hundred cases generated between 1996 and 2006 were randomly examined and divided into 2 subcohorts: 1750 patients were sedated with midazolam and fentanyl, and 1750 patients received propofol, in subanesthetic increments, in addition to midazolam and fentanyl. Initial sedation was established using midazolam and fentanyl in both subcohorts. The second subcohort received propofol during times of noxious stimulation. Patient exposure to 2 or more oxygen desaturations below 94% was uncommon. The variables that were significantly associated with low saturations were age, gender, and weight. Neither the dose of midazolam nor the additional use of propofol was a significant risk factor. ASA classification (I or II) was not a determinant of risk. The data, within the limitations of the study, showed that a single operator/sedationist, supported by a well-trained team of nurses, can consistently maintain safe oxygen saturation levels. The additional use of propofol did not increase exposure to hypoxemia. PMID:21882986
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Association of oral breathing with dental malocclusions and general health in children.
Jiménez, Emilio L; Barrios, Rocío; Calvo, Juan C; de la Rosa, Maria T; Campillo, José S; Bayona, José C; Bravo, Manuel
2017-06-01
The aims of this study were to analyze the association of oral breathing with dental malocclusions and aspects of general health such as acute illnesses, oxygen saturation in blood and its possible implication in the process of nutrition. A prevalence analytic study was carried out. Five dentists explored to children between 6 and 12 years and measured their oxygen saturation. Parents completed a questionnaire of 11 items about general health (colds, ear infections, tonsillitis and taking antibiotics) and the food preferences of their children. At the end, children were classified in oral breathing group (prevalence cases) or nasal breathing group (controls). There were statistical differences between cases (452 children) and controls (752 children) in the facial morphometric measurements. Oral breathing children had statistically less percentage of oxygen saturation than controls (92.3±3.3% versus 96.5±2.3%), took less time to have lunch and preferred less consistent and sugary food. Cases had had more prevalence of pathologies in the last year and of taking the antibiotics. This group also had higher prevalence of allergies compared with controls group (P<0.001). Oral breathing is significantly associated with specific dental malocclusions and important aspects of general health such as oxygen saturation and the nutrition. On the same line, oral breathing is related to a significantly higher prevalence of allergies and a significantly more likely getting sick and taking medication.
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Mebius, Mirthe J; van der Laan, Michelle E; Verhagen, Elise A; Roofthooft, Marcus Tr; Bos, Arend F; Kooi, Elisabeth Mw
2016-12-01
Evidence suggests that hypoxic-ischemic brain injury in infants with congenital heart disease already occurs during early life. The aim of our study was, therefore, to assess the course of regional cerebral oxygen saturation (r c SO 2 ) and fractional tissue oxygen extraction (FTOE) during the first 72h after birth in infants with prenatally diagnosed duct-dependent congenital heart disease. In addition, we identified clinical parameters that were associated with r c SO 2 . We included 56 infants with duct-dependent congenital heart disease. We measured arterial oxygen saturation (SpO 2 ) and r c SO 2 during the first 72h after birth. Simultaneously, we calculated FTOE. We observed median r c SO 2 values of approximately 60%, a decreasing FTOE from 0.34 on day 1 to 0.28 on day 3 and stable preductal SpO 2 values around 90%. Several clinical variables were associated with r c SO 2 . In a multiple linear regression model only type of CHD and preductal SpO 2 were significant predictors of r c SO 2 during the first three days after birth. Infants with a duct-dependent pulmonary circulation had up to 12% lower r c SO 2 values than infants with a duct-dependent systemic circulation. We demonstrated that, during the first three days after birth, cerebral oxygen saturation is low in infants with duct-dependent congenital heart disease. Furthermore, this study provides preoperative reference values of r c SO 2 and FTOE in infants with duct-dependent CHD. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.
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Passino, Claudio; Cencetti, Simone; Spadacini, Giammario; Quintana, Robert; Parker, Daryl; Robergs, Robert; Appenzeller, Otto; Bernardi, Luciano
2007-09-01
To assess the effects of acute exposure to simulated high altitude on baroreflex control of mean cerebral blood flow velocity (MCFV). We compared beat-to-beat changes in RR interval, arterial blood pressure, mean MCFV (by transcranial Doppler velocimetry in the middle cerebral artery), end-tidal CO2, oxygen saturation and respiration in 19 healthy subjects at baseline (Albuquerque, 1779 m), after acute exposure to simulated high altitude in a hypobaric chamber (barometric pressure as at 5000 m) and during oxygen administration (to achieve 100% oxygen saturation) at the same barometric pressure (HOX). Baroreflex control on each signal was assessed by univariate and bivariate power spectral analysis performed on time series obtained during controlled (15 breaths/min) breathing, before and during baroreflex modulation induced by 0.1-Hz sinusoidal neck suction. At baseline, neck suction was able to induce a clear increase in low-frequency power in MCFV (P<0.001) as well as in RR and blood pressure. At high altitude, MCFV, as well as RR and blood pressure, was still able to respond to neck suction (all P<0.001), compared to controlled breathing alone, despite marked decreases in end-tidal CO2 and oxygen saturation at high altitude. A similar response was obtained at HOX. Phase delay analysis excluded a passive transmission of low-frequency oscillations from arterial pressure to cerebral circulation. During acute exposure to high altitude, cerebral blood flow is still modulated by the autonomic nervous system through the baroreflex, whose sensitivity is not affected by changes in CO2 and oxygen saturation levels.
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English, Mike; Berkley, James; Mwangi, Isiah; Mohammed, Shebbe; Ahmed, Maimuna; Osier, Faith; Muturi, Neema; Ogutu, Bernhards; Marsh, Kevin; Newton, Charles R. J. C.
2003-01-01
OBJECTIVE: To investigate whether the outpatient, syndrome-based approach of the Integrated Management of Childhood Illness (IMCI) protocol could be extended to the inpatient arena to give clear and simple minimum standards of care for poorly resourced facilities. METHODS: A prospective, one-year admission cohort retrospectively compared hypothetical performance of syndrome-based management with paediatrician-defined final diagnosis. Admission syndrome definitions were based on local adaptations to the IMCI protocol that encompassed 20 clinical features, measurement of oxygen saturation, and malaria microscopy. FINDINGS: After 315 children with clinically obvious diagnoses (e.g. sickle cell disease and burns) were excluded, 3705 admission episodes were studied. Of these, 2334 (63%) met criteria for at least one severe syndrome (mortality 8% vs <1% for "non-severe" cases), and half of these had features of two or more severe syndromes. No cases of measles were seen. Syndrome-based treatment would have been appropriate (sensitivity >95%) for severe pneumonia, severe malaria, and diarrhoea with severe dehydration, and probably for severe malnutrition (sensitivity 71%). Syndrome-directed treatment suggested the use of broad-spectrum antibiotics in 75/133 (56% sensitivity) children with bacteraemic and 63/71 (89% sensitivity) children with meningitis. CONCLUSIONS: Twenty clinical features, oxygen saturation measurements, and results of malaria blood slides could be used for inpatient, syndrome-based management of acute paediatric admissions. The addition of microscopy of the cerebrospinal fluid and haemoglobin measurements would improve syndrome-directed treatment considerably. This approach might rationalize admission policy and standardize inpatient paediatric care in resource-poor countries, although the clinical detection of bacteraemia remains a problem. PMID:12764512
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Validation of Watch-PAT-200 Against Polysomnography During Pregnancy
O'Brien, Louise M.; Bullough, Alexandra S.; Shelgikar, Anita V.; Chames, Mark C.; Armitage, Roseanne; Chervin, Ronald D.
2012-01-01
Study Objectives: To determine the relationships between key variables obtained from ambulatory polysomnography (PSG) and the wrist-worn Watch-PAT 200 device in pregnant women. Methods: In this prospective cohort study, women in their third trimester of pregnancy underwent full overnight home PSG using the 22-channel MediPalm system and the Watch-PAT 200 device. PSGs were scored by a blinded, experienced technologist using AASM 2007 criteria; the Watch-PAT was scored automatically by the manufacturer's proprietary software. Results: A total of 31 pregnant women were studied. Mean age was 30.2 ± 7.1 years; mean gestational age was 33.4 ± 3.0 weeks; mean BMI was 31.9 ± 8.1 kg/m2; 39% of women were nulliparous. Key variables generated by PSG and Watch-PAT correlated well over a wide range, including the apnea-hypopnea index (AHI, r = 0.76, p < 0.001); respiratory disturbance index (RDI, r = 0.68, p < 0.001), mean oxygen saturation (r = 0.94, p < 0.001), and minimum oxygen saturation (r = 0.88, p < 0.001). The area under the curve for AHI ≥ 5 and RDI ≥ 10 were 0.96 and 0.94, respectively. Association between stage 3 sleep on PSG and deep sleep on Watch-PAT was poor. Watch-PAT tended to overscore RDI, particularly as severity increased. Conclusions: Among pregnant women, Watch-PAT demonstrates excellent sensitivity and specificity for identification of obstructive sleep apnea, defined as AHI ≥ 5 on full PSG. Watch-PAT may overestimate RDI somewhat, especially at high RDI values. Citation: O'Brien LM; Bullough AS; Shelgikar AV; Chames MC; Armitage R; Chervin RD. Validation of Watch-Pat-200 against polysomnography during pregnancy. J Clin Sleep Med 2012;8(3):287-294. PMID:22701386
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Zhou, Bao-Chun; Liu, Li-Jun; Liu, Bing
2016-09-01
Although hyperbaric oxygen (HBO) therapy can promote the recovery of neural function in patients who have suffered traumatic brain injury (TBI), the underlying mechanism is unclear. We hypothesized that hyperbaric oxygen treatment plays a neuroprotective role in TBI by increasing regional transcranial oxygen saturation (rSO 2 ) and oxygen partial pressure (PaO 2 ). To test this idea, we compared two groups: a control group with 20 healthy people and a treatment group with 40 TBI patients. The 40 patients were given 100% oxygen of HBO for 90 minutes. Changes in rSO 2 were measured. The controls were also examined for rSO 2 and PaO 2 , but received no treatment. rSO 2 levels in the patients did not differ significantly after treatment, but levels before and after treatment were significantly lower than those in the control group. PaO 2 levels were significantly decreased after the 30-minute HBO treatment. Our findings suggest that there is a disorder of oxygen metabolism in patients with sub-acute TBI. HBO does not immediately affect cerebral oxygen metabolism, and the underlying mechanism still needs to be studied in depth.
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Roffe, Christine; Nevatte, Tracy; Bishop, Jon; Sim, Julius; Penaloza, Cristina; Jowett, Susan; Ives, Natalie; Gray, Richard; Ferdinand, Phillip; Muddegowda, Girish
2018-03-01
Stroke is a major cause of death and disability worldwide. Hypoxia is common after stroke and is associated with worse outcomes. Oxygen supplementation could prevent hypoxia and secondary brain damage. (1) To assess whether or not routine low-dose oxygen supplementation in patients with acute stroke improves outcome compared with no oxygen; and (2) to assess whether or not oxygen given at night only, when oxygen saturation is most likely to be low, is more effective than continuous supplementation. Multicentre, prospective, randomised, open, blinded-end point trial. Secondary care hospitals with acute stroke wards. Adult stroke patients within 24 hours of hospital admission and 48 hours of stroke onset, without definite indications for or contraindications to oxygen or a life-threatening condition other than stroke. Allocated by web-based minimised randomisation to: (1) continuous oxygen: oxygen via nasal cannula continuously (day and night) for 72 hours after randomisation at a flow rate of 3 l/minute if baseline oxygen saturation was ≤ 93% or 2 l/minute if > 93%; (2) nocturnal oxygen: oxygen via nasal cannula overnight (21:00-07:00) for three consecutive nights. The flow rate was the same as the continuous oxygen group; and (3) control: no routine oxygen supplementation unless required for reasons other than stroke. Primary outcome: disability assessed by the modified Rankin Scale (mRS) at 3 months by postal questionnaire (participant aware, assessor blinded). Secondary outcomes at 7 days: neurological improvement, National Institutes of Health Stroke Scale (NIHSS), mortality, and the highest and lowest oxygen saturations within the first 72 hours. Secondary outcomes at 3, 6, and 12 months: mortality, independence, current living arrangements, Barthel Index, quality of life (European Quality of Life-5 Dimensions, three levels) and Nottingham Extended Activities of Daily Living scale by postal questionnaire. In total, 8003 patients were recruited between 24 April 2008 and 17 June 2013 from 136 hospitals in the UK [continuous, n = 2668; nocturnal, n = 2667; control, n = 2668; mean age 72 years (standard deviation 13 years); 4398 (55%) males]. All prognostic factors and baseline characteristics were well matched across the groups. Eighty-two per cent had ischaemic strokes. At baseline the median Glasgow Coma Scale score was 15 (interquartile range 15-15) and the mean and median NIHSS scores were 7 and 5 (range 0-34), respectively. The mean oxygen saturation at randomisation was 96.6% in the continuous and nocturnal oxygen groups and 96.7% in the control group. Primary outcome: oxygen supplementation did not reduce disability in either the continuous or the nocturnal oxygen groups. The unadjusted odds ratio for a better outcome (lower mRS) was 0.97 [95% confidence interval (CI) 0.89 to 1.05; p = 0.5] for the combined oxygen groups (both continuous and nocturnal together) ( n = 5152) versus the control ( n = 2567) and 1.03 (95% CI 0.93 to 1.13; p = 0.6) for continuous versus nocturnal oxygen. Secondary outcomes: oxygen supplementation significantly increased oxygen saturation, but did not affect any of the other secondary outcomes. Severely hypoxic patients were not included. Routine low-dose oxygen supplementation in stroke patients who are not severely hypoxic is safe, but does not improve outcome after stroke. To investigate the causes of hypoxia and develop methods of prevention. Current Controlled Trials ISRCTN52416964 and European Union Drug Regulating Authorities Clinical Trials (EudraCT) number 2006-003479-11. This project was funded by the National Institute for Health Research (NIHR) Research for Patient Benefit and Health Technology Assessment programmes and will be published in full in Health Technology Assessment ; Vol. 22, No. 14. See the NIHR Journals Library website for further project information.
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NASA Astrophysics Data System (ADS)
Grosenick, Dirk; Cantow, Kathleen; Arakelyan, Karen; Wabnitz, Heidrun; Flemming, Bert; Skalweit, Angela; Ladwig, Mechthild; Macdonald, Rainer; Niendorf, Thoralf; Seeliger, Erdmann
2015-07-01
We have developed a hybrid approach to investigate the dynamics of perfusion and oxygenation in the kidney of rats under pathophysiologically relevant conditions. Our approach combines near-infrared spectroscopy to quantify hemoglobin concentration and oxygen saturation in the renal cortex, and an invasive probe method for measuring total renal blood flow by an ultrasonic probe, perfusion by laser-Doppler fluxmetry, and tissue oxygen tension via fluorescence quenching. Hemoglobin concentration and oxygen saturation were determined from experimental data by a Monte Carlo model. The hybrid approach was applied to investigate and compare temporal changes during several types of interventions such as arterial and venous occlusions, as well as hyperoxia, hypoxia and hypercapnia induced by different mixtures of the inspired gas. The approach was also applied to study the effects of the x-ray contrast medium iodixanol on the kidney.
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Dix, Laura Marie Louise; Weeke, Lauren Carleen; de Vries, Linda Simone; Groenendaal, Floris; Baerts, Willem; van Bel, Frank; Lemmers, Petra Maria Anna
2017-08-01
To evaluate the effects of acute arterial carbon dioxide partial pressure changes on cerebral oxygenation and electrical activity in infants born preterm. This retrospective observational study included ventilated infants born preterm with acute fluctuations of continuous end-tidal CO 2 (etCO 2 ) as a surrogate marker for arterial carbon dioxide partial pressure, during the first 72 hours of life. Regional cerebral oxygen saturation and fractional tissue oxygen extraction were monitored with near-infrared spectroscopy. Brain activity was monitored with 2-channel electroencephalography. Spontaneous activity transients (SATs) rate (SATs/minute) and interval between SATs (in seconds) were calculated. Ten-minute periods were selected for analysis: before, during, and after etCO 2 fluctuations of ≥5 mm Hg. Thirty-eight patients (mean ± SD gestational age of 29 ± 1.8 weeks) were included, with 60 episodes of etCO 2 increase and 70 episodes of etCO 2 decrease. During etCO 2 increases, brain oxygenation increased (regional cerebral oxygen saturation increased, fractional tissue oxygen extraction decreased; P < .01) and electrical activity decreased (SATs/minute decreased, interval between SATs increased; P < .01). All measures recovered when etCO 2 returned to baseline. During etCO 2 decreases, brain oxygenation decreased (regional cerebral oxygen saturation decreased, fractional tissue oxygen extraction decreased; P < .01) and brain activity increased (SATs/minute increased, P < .05), also with recovery after return of etCO 2 to baseline. An acute increase in etCO 2 is associated with increased cerebral oxygenation and decreased brain activity, whereas an acute decrease is associated with decreased cerebral oxygenation and slightly increased brain activity. Combining continuous CO 2 monitoring with near-infrared spectroscopy may enable the detection of otherwise undetected fluctuations in arterial carbon dioxide partial pressure that may be harmful to the neonatal brain. Copyright © 2017 Elsevier Inc. All rights reserved.
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NASA Astrophysics Data System (ADS)
Krasnovsky, A. A.; Rоumbal, Ya. V.; Strizhakov, A. A.
2008-06-01
The oxygenation rates of the 1O2 trap, 1,3-diphenylisobenzofuran were measured in air-saturated H2O-sodium dodecyl sulfate dispersions, ethanol, methanol and benzene upon direct excitation of dissolved oxygen by infrared (1269 ± 1 nm) laser radiation. In aqueous dispersions, variation of the detergent concentration from 0.1 to 1 M resulted in the 2.5-time increase of the photooxygenation rate. The absorbance and molar absorption coefficients of oxygen were estimated in all tested systems, water and the micellar phase of detergent dispersions and compared with the rate constants of 1O2 radiative deactivation obtained from the measurement of the quantum yields of photosensitized 1O2 phosphorescence.
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Ambulatory vital signs in the workup of pulmonary embolism using a standardized 3-minute walk test.
Amin, Qamar; Perry, Jeffrey J; Stiell, Ian G; Mohapatra, Subhra; Alsadoon, Abdulaziz; Rodger, Marc
2015-05-01
Diagnosing pulmonary embolism can be difficult given its highly variable clinical presentation. Our objective was to determine whether a decrease in oxygen saturation or an increase in heart rate while ambulating could be used as an objective tool in the diagnosis of pulmonary embolism. This was a two-site tertiary-care-centre prospective cohort study that enrolled adult emergency department or thrombosis clinic patients with suspected or newly confirmed pulmonary embolism. Patients were asked to participate in a standardized 3-minute walk test, which assessed ambulatory heart rate and ambulatory oxygen saturation. The primary outcome was pulmonary embolism. We enrolled 114 patients, including 30 with pulmonary embolism (26.3%). A ≥2% absolute decrease in ambulatory oxygen saturation and an ambulatory change in heart rate >10 beats per minute (BPM) were significantly associated with pulmonary embolism. An ambulatory heart rate change of >10 BPM had a sensitivity of 96.6% (95% confidence interval [CI] 83.3 to 99.4) and a specificity of 31.0% (95% CI 22.1 to 45.0) for pulmonary embolism. A ≥2% absolute decrease ambulatory oxygen saturation had a sensitivity of 80.2% (95% CI 62.7 to 90.5) and a specificity of 39.3% (95% CI 29.5 to 50.0) for pulmonary embolism. The combination of both variables yielded a sensitivity of 100.0% (95% CI 87.0 to 100.0) and a specificity of 11.0% (95% CI 6.6 to 21.0). In summary, our study found that an ambulatory heart rate change of >10 BPM or a ≥2% absolute decrease in ambulatory oxygen saturation from baseline during a standardized 3-minute walk test are highly correlated with pulmonary embolism. Although the findings appear promising, neither of these variables can currently be recommended as a screening tool for pulmonary embolism until larger prospective studies examine their performance either alone or with pre-existing rules.
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Effects of dexmedetomidine infusion during spinal anesthesia on hemodynamics and sedation
Tarıkçı Kılıç, Ebru; Aydın, Gaye
2018-01-01
ABSTRACT Background: We evaluated the effects of intravenous dexmedetomidine during spinal anesthesia on hemodynamics, respiratory rate, oxygen saturation, sedpain, and compared them with those of saline infusion. Sixty American Society of Anesthesiologists physical status I and II cases were randomly divided into two groups. Patients were connected to the monitor after premedication, and spinal anesthesia was administered. Sensory and motor blockades were assessed using pinprick test and Bromage scale, respectively. Group I received dexmedetomidine infusion and Group II received saline infusion. Throughout the infusion process, hemodynamic data, respiratory rate, oxygen saturation, sedation, pain, Bromage score, amnesia, bispectral index, and side effects were recorded. Postoperative hemodynamic measurements, oxygen saturation, sedation, pain scores were obtained. Sedation and pain were evaluated using the Ramsay and visual analog scales, respectively. Analgesics were administered in cases with high scores on the visual analog scale. Postoperative analgesic consumption, side effects, treatments were recorded. No significant differences were found between the groups with respect to oxygen saturation, respiratory rate, pain, and side effects in the intraoperative period. Time to onset of sensorial block, maximum sensorial block, onset of motor block, and maximum motor block; bispectral index values; and apex heartbeat until 80 min of infusion, systolic arterial blood pressure until 90 min, and diastolic arterial blood pressure until 50 min were lower, whereas amnesia and sedation levels were higher in dexmedetomidine group. Postoperative pain and analgesic requirement were not different. Apex heartbeat at 15 min and systolic arterial blood pressure at 30 min were lower and sedation scores were higher in the dexmedetomidine infusion group. We demonstrated dexmedetomidine infusion had a hemodynamic depressant effect intraoperatively whereas it had no significant effect on peripheral oxygen saturation, respiratory rate, visual analog scale scores, and side effects. Dexmedetomidine infusion enhanced motor and sensory blockade quality and induced amnesia and sedation. PMID:29457538
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Capraro, Geoffrey A; Mader, Timothy J; Coughlin, Bret F; Lovewell, Carolanne; St Louis, Myron R L; Tirabassi, Michael; Wadie, George; Smithline, Howard A
2007-04-01
To assess whether near-infrared spectroscopy can detect testicular hypoxia in a sheep model of testicular torsion within 6 hours of experimental torsion. This was a randomized, controlled, nonblinded study. Trans-scrotal, near-infrared, spectroscopy-derived testicular tissue saturation of oxygen values were obtained from the posterior hemiscrota of 6 anesthetized sheep at baseline and every 15 minutes for 6 hours after either experimental-side, 720-degree, unilateral, medial testicular torsion and orchidopexy or control-side sham procedure with orchidopexy and then for 75 minutes after reduction of torsion and pexy. Color Doppler ultrasonography was performed every 30 minutes to confirm loss of vascular flow on the experimental side, return of flow after torsion reduction, and preserved flow on the control side. Near infrared spectroscopy detected a prompt, sustained reduction in testicular tissue saturation of oxygen after experimental torsion. Further, it documented a rapid return of these values to pretorsion levels after reduction of torsion. Experimental-side testicular tissue saturation of oxygen fell from a median value of 59% (interquartile range [IQR] 57% to 69%) at baseline to 14% (IQR 11% to 29%) at 2.5 hours of torsion, and postreduction values were approximately 70%. Control-side testicular tissue saturation of oxygen values increased from a median value of 67% (IQR 59% to 68%) at baseline to 77% (IQR 77% to 94%) at 2.5 hours and remained at approximately 80% for the entire protocol. The difference in median testicular tissue saturation of oxygen between experimental and control sides, using the Friedman test, was found to be significant (P=.017). This study demonstrates the feasibility, in a sheep model, of using near-infrared spectroscopy for the noninvasive diagnosis of testicular torsion and for quantification of reperfusion after torsion reduction. The applicability of these findings, from an animal model using complete torsion, to the clinical setting remains to be established.
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Díaz-Regañón, Genaro; Miñambres, Eduardo; Holanda, Marisol; González-Herrera, Segundo; López-Espadas, Francisco; Garrido-Díaz, Carlos
2002-12-01
To assess the usefulness of venous oxygen saturation in the jugular bulb (SjO(2)) as a complementary test for the diagnosis of brain death. Prospective observational study. Polytrauma intensive care unit (ICU) of an acute-care teaching hospital in Santander, Spain. We studied 118 (44%) out of 270 patients with severe head injury and intracranial hemorrhage meeting criteria of brain death (lack of cardiac response to atropine, unresponsive apnea, and iso-electric EEG in the absence of shock, hypotension and treatment with muscle relaxants and/or central nervous system (CNS) depressant drugs). At the moment at which clinical diagnosis of brain death was made and an iso-electric EEG was obtained, simultaneous oxygen saturation in central venous blood (right atrium) (SvO(2)) and jugular venous bulb (SjO(2)) samples was measured. The ratio between SvO(2) and SjO(2), expressed as CvjO(2) (the so-called central venous-jugular bulb oxygen saturation rate; CvjO(2) = SvO(2)/SjO(2)) was calculated. CvjO(2) less than 1 was obtained in 114 patients [mean (SD): 0.89 (0.02)], whereas CvjO(2) greater than 1 was obtained in only 4 (3.38%). In the group of 152 survivors, a single patient was discharged from the ICU in a vegetative state in which CvjO(2) was below 1. CvjO(2)as a complementary test for the diagnosis of brain death showed 96.6% sensitivity, 99.3% specificity, and 99.1% and 97.4% positive and negative predictive values, respectively. Central venous-jugular bulb oxygen saturation rate below 1 together with accepted clinical criteria (unresponsive coma with brainstem areflexia) provides non-invasive assessment of cerebral circulatory arrest that can help to suspect brain death.
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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."
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Critical oxygen levels and metabolic suppression in oceanic oxygen minimum zones.
Seibel, Brad A
2011-01-15
The survival of oceanic organisms in oxygen minimum zones (OMZs) depends on their total oxygen demand and the capacities for oxygen extraction and transport, anaerobic ATP production and metabolic suppression. Anaerobic metabolism and metabolic suppression are required for daytime forays into the most extreme OMZs. Critical oxygen partial pressures are, within a range, evolved to match the minimum oxygen level to which a species is exposed. This fact demands that low oxygen habitats be defined by the biological response to low oxygen rather than by some arbitrary oxygen concentration. A broad comparative analysis of oxygen tolerance facilitates the identification of two oxygen thresholds that may prove useful for policy makers as OMZs expand due to climate change. Between these thresholds, specific physiological adaptations to low oxygen are required of virtually all species. The lower threshold represents a limit to evolved oxygen extraction capacity. Climate change that pushes oxygen concentrations below the lower threshold (~0.8 kPa) will certainly result in a transition from an ecosystem dominated by a diverse midwater fauna to one dominated by diel migrant biota that must return to surface waters at night. Animal physiology and, in particular, the response of animals to expanding hypoxia, is a critical, but understudied, component of biogeochemical cycles and oceanic ecology. Here, I discuss the definition of hypoxia and critical oxygen levels, review adaptations of animals to OMZs and discuss the capacity for, and prevalence of, metabolic suppression as a response to temporary residence in OMZs and the possible consequences of climate change on OMZ ecology.
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Dissolved oxygen saturation controls PAH biodegradation in freshwater estuary sediments.
Boyd, T J; Montgomery, M T; Steele, J K; Pohlman, J W; Reatherford, S R; Spargo, B J; Smith, D C
2005-02-01
Polycyclic aromatic hydrocarbons (PAHs) are common contaminants in terrestrial and aquatic environments and can represent a significant constituent of the carbon pool in coastal sediments. We report here the results of an 18-month seasonal study of PAH biodegradation and heterotrophic bacterial production and their controlling biogeochemical factors from 186 sediment samples taken in a tidally influenced freshwater estuary. For each sampling event, measurements were averaged from 25-45 stations covering approximately 250 km(2). There was a clear relationship between bacterial production and ambient temperature, but none between production and bottom water dissolved oxygen (DO) % saturation or PAH concentrations. In contrast with other studies, we found no effect of temperature on the biodegradation of naphthalene, phenanthrene, or fluoranthene. PAH mineralization correlated with bottom water DO saturation above 70% (r(2) > 0.99). These results suggest that the proportional utilization of PAH carbon to natural organic carbon is as much as three orders of magnitude higher during cooler months, when water temperatures are lower and DO % saturation is higher. Infusion of cooler, well-oxygenated water to the water column overlying contaminated sediments during the summer months may stimulate PAH metabolism preferentially over non-PAH organic matter.
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Oxygen concentration inside a functioning photosynthetic cell.
Kihara, Shigeharu; Hartzler, Daniel A; Savikhin, Sergei
2014-05-06
The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth's atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.
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Oxygen Concentration Inside a Functioning Photosynthetic Cell
Kihara, Shigeharu; Hartzler, Daniel A.; Savikhin, Sergei
2014-01-01
The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth’s atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere. PMID:24806920
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42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 42 Public Health 1 2013-10-01 2013-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...
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42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 42 Public Health 1 2012-10-01 2012-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...
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42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 42 Public Health 1 2011-10-01 2011-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...
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42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 42 Public Health 1 2014-10-01 2014-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...
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42 CFR 84.86 - Component parts exposed to oxygen pressures; minimum requirements.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 42 Public Health 1 2010-10-01 2010-10-01 false Component parts exposed to oxygen pressures; minimum requirements. 84.86 Section 84.86 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY...
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NASA Technical Reports Server (NTRS)
Jolliff, Bradley L.; Haskin, Larry A.; Colson, Russell O.; Wadhwa, Meenakshi
1993-01-01
Compositions, including REEs determined by ion microprobe, of apatite and whitlockite in lunar rock assemblages rich in incompatible trace elements, are presented. Concentrations of REEs in lunar whitlockites are high, ranging from about 1.2 to 2.1 REEs (lanthanides + Y) per 56 oxygens. This slightly exceeds the level of two REE atoms per 56 oxygens at which the dominant substitution theoretically becomes saturated. This saturation effect leads to whitlockite REE(3+) D values at typical lunar whitlockite REE concentrations which are 30-40 percent lower than the D values at low concentrations. The halogen-to-phosphorous ratio in lunar melts is a key factor determining the REE distribution with crystalline assemblages. As long as P and REE concentrations of melts are in KREEP-like proportions, one or both of the phosphates will saturate in melts at similar REE concentrations.
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2016-01-01
A novel method of extracting heart rate and oxygen saturation from a video-based biosignal is described. The method comprises a novel modular continuous wavelet transform approach which includes: performing the transform, undertaking running wavelet archetyping to enhance the pulse information, extraction of the pulse ridge time–frequency information [and thus a heart rate (HRvid) signal], creation of a wavelet ratio surface, projection of the pulse ridge onto the ratio surface to determine the ratio of ratios from which a saturation trending signal is derived, and calibrating this signal to provide an absolute saturation signal (SvidO2). The method is illustrated through its application to a video photoplethysmogram acquired during a porcine model of acute desaturation. The modular continuous wavelet transform-based approach is advocated by the author as a powerful methodology to deal with noisy, non-stationary biosignals in general. PMID:27382479
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Acute hypoxia in a simulated high-altitude airdrop scenario due to oxygen system failure.
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.
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DOT National Transportation Integrated Search
1966-09-01
General aviation pilots are increasingly ascending to altitudes exceeding ten thousand feet. As one becomes exposed to heights above twelve thousand feet, blood oxygen saturation diminishes in accordance with a predicable schedule. Recommended measur...
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Capossela, K M; Brill, R W; Fabrizio, M C; Bushnell, P G
2012-08-01
To quantify the tolerance of summer flounder Paralichthys dentatus to episodic hypoxia, resting metabolic rate, oxygen extraction, gill ventilation and heart rate were measured during acute progressive hypoxia at the fish's acclimation temperature (22° C) and after an acute temperature increase (to 30° C). Mean ±s.e. critical oxygen levels (i.e. the oxygen levels below which fish could not maintain aerobic metabolism) increased significantly from 27 ± 2% saturation (2·0 ± 0·1 mg O(2) l(-1)) at 22° C to 39 ± 2% saturation (2·4 ± 0·1 mg O(2) l(-1)) at 30° C. Gill ventilation and oxygen extraction changed immediately with the onset of hypoxia at both temperatures. The fractional increase in gill ventilation (from normoxia to the lowest oxygen level tested) was much larger at 22° C (6·4-fold) than at 30° C (2·7-fold). In contrast, the fractional decrease in oxygen extraction (from normoxia to the lowest oxygen levels tested) was similar at 22° C (1·7-fold) and 30° C (1·5-fold), and clearly smaller than the fractional changes in gill ventilation. In contrast to the almost immediate effects of hypoxia on respiration, bradycardia was not observed until 20 and 30% oxygen saturation at 22 and 30° C, respectively. Bradycardia was, therefore, not observed until below critical oxygen levels. The critical oxygen levels at both temperatures were near or immediately below the accepted 2·3 mg O(2) l(-1) hypoxia threshold for survival, but the increase in the critical oxygen level at 30° C suggests a lower tolerance to hypoxia after an acute increase in temperature. © 2012 The Authors. Journal of Fish Biology © 2012 The Fisheries Society of the British Isles.
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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.
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NASA Astrophysics Data System (ADS)
Björnbom, Pehr
2016-03-01
In the first part of this work equilibrium temperature profiles in fluid columns with ideal gas or ideal liquid were obtained by numerically minimizing the column energy at constant entropy, equivalent to maximizing column entropy at constant energy. A minimum in internal plus potential energy for an isothermal temperature profile was obtained in line with Gibbs' classical equilibrium criterion. However, a minimum in internal energy alone for adiabatic temperature profiles was also obtained. This led to a hypothesis that the adiabatic lapse rate corresponds to a restricted equilibrium state, a type of state in fact discussed already by Gibbs. In this paper similar numerical results for a fluid column with saturated air suggest that also the saturated adiabatic lapse rate corresponds to a restricted equilibrium state. The proposed hypothesis is further discussed and amended based on the previous and the present numerical results and a theoretical analysis based on Gibbs' equilibrium theory.
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Dissolved oxygen content as an index of water quality in San Vicente Bay, Chile (36 degrees 45'S).
Rudolph, Anny; Ahumada, Ramón; Pérez, Claudio
2002-08-01
The present report describes some effects of industrial and municipal effluents on the waters of San Vicente Bay. Analyses of the main substances contained in the fishing industry effluent suggest rating criteria based on the oxygen saturation of the water as an assessment of organic pollution. Six cruises were carried out throughout the Bay, from June to December 1996. Water samples were analyzed for dissolved oxygen, oil and grease content, and sediment samples for organic matter content. Water parameters (salinity, temperature) were used to characterize the Bay's hydrography, and to calculate values for oxygen saturation. The measurements demonstrated a local broad range of oxygen deficit, with a maximum of 45% in the winter to 95% in the spring. In November more than 65% of the Bay's area showed oxygen deficits greater than 40%. Organic matter was unusually high in sediments along the northern sector of the Bay. The results suggest that the oxygen depletion was a representative parameter for establishing a relative scale of water quality in this Bay.
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75 FR 76525 - Food Labeling; Health Claim; Phytosterols and Risk of Coronary Heart Disease
Federal Register 2010, 2011, 2012, 2013, 2014
2010-12-08
... b. Dietary supplements 3. Other Requirements a. Disqualifying total fat level b. Low saturated fat and low cholesterol criteria c. Trans fat considerations d. Minimum nutrient contribution requirement... diet low in saturated fat and cholesterol, (2) uses the term plant (or vegetable oil) sterol esters or...
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(I Can't Get No) Saturation: A simulation and guidelines for sample sizes in qualitative research.
van Rijnsoever, Frank J
2017-01-01
I explore the sample size in qualitative research that is required to reach theoretical saturation. I conceptualize a population as consisting of sub-populations that contain different types of information sources that hold a number of codes. Theoretical saturation is reached after all the codes in the population have been observed once in the sample. I delineate three different scenarios to sample information sources: "random chance," which is based on probability sampling, "minimal information," which yields at least one new code per sampling step, and "maximum information," which yields the largest number of new codes per sampling step. Next, I use simulations to assess the minimum sample size for each scenario for systematically varying hypothetical populations. I show that theoretical saturation is more dependent on the mean probability of observing codes than on the number of codes in a population. Moreover, the minimal and maximal information scenarios are significantly more efficient than random chance, but yield fewer repetitions per code to validate the findings. I formulate guidelines for purposive sampling and recommend that researchers follow a minimum information scenario.
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NASA Astrophysics Data System (ADS)
Balbín, R.; López-Jurado, J. L.; Aparicio-González, A.; Serra, M.
2014-10-01
Oceanographic data obtained between 2001 and 2011 by the Spanish Institute of Oceanography (IEO, Spain) have been used to characterise the spatial distribution and the temporal variability of the dissolved oxygen around the Balearic Islands (Mediterranean Sea). The study area includes most of the Western Mediterranean Sea, from the Alboran Sea to Cape Creus, at the border between France and Spain. Dissolved oxygen (DO) at the water surface is found to be in a state of equilibrium exchange with the atmosphere. In the spring and summer a subsurface oxygen supersaturation is observed due to the biological activity, above the subsurface fluorescence maximum. Minimum observed values of dissolved oxygen are related to the Levantine Intermediate Waters (LIW). An unusual minimum of dissolved oxygen concentrations was also recorded in the Alboran Sea Oxygen Minimum Zone. The Western Mediterranean Deep Waters (WMDW) and the Western Intermediate Waters (WIW) show higher values of dissolved oxygen than the Levantine Intermediate Waters due to their more recent formation. Using these dissolved oxygen concentrations it is possible to show that the Western Intermediate Waters move southwards across the Ibiza Channel and the deep water circulates around the Balearic Islands. It has also been possible to characterise the seasonal evolution of the different water masses and their dissolved oxygen content in a station in the Algerian sub-basin.
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A reflectance model for non-contact mapping of venous oxygen saturation using a CCD camera
NASA Astrophysics Data System (ADS)
Li, Jun; Dunmire, Barbrina; Beach, Kirk W.; Leotta, Daniel F.
2013-11-01
A method of non-contact mapping of venous oxygen saturation (SvO2) is presented. A CCD camera is used to image skin tissue illuminated alternately by a red (660 nm) and an infrared (800 nm) LED light source. Low cuff pressures of 30-40 mmHg are applied to induce a venous blood volume change with negligible change in the arterial blood volume. A hybrid model combining the Beer-Lambert law and the light diffusion model is developed and used to convert the change in the light intensity to the change in skin tissue absorption coefficient. A simulation study incorporating the full light diffusion model is used to verify the hybrid model and to correct a calculation bias. SvO2 in the fingers, palm, and forearm for five volunteers are presented and compared with results in the published literature. Two-dimensional maps of venous oxygen saturation are given for the three anatomical regions.
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Oximeter for reliable clinical determination of blood oxygen saturation in a fetus
Robinson, Mark R.; Haaland, David M.; Ward, Kenneth J.
1996-01-01
With the crude instrumentation now in use to continuously monitor the status of the fetus at delivery, the obstetrician and labor room staff not only over-recognize the possibility of fetal distress with the resultant rise in operative deliveries, but at times do not identify fetal distress which may result in preventable fetal neurological harm. The invention, which addresses these two basic problems, comprises a method and apparatus for non-invasive determination of blood oxygen saturation in the fetus. The apparatus includes a multiple frequency light source which is coupled to an optical fiber. The output of the fiber is used to illuminate blood containing tissue of the fetus. In the preferred embodiment, the reflected light is transmitted back to the apparatus where the light intensities are simultaneously detected at multiple frequencies. The resulting spectrum is then analyzed for determination of oxygen saturation. The analysis method uses multivariate calibration techniques that compensate for nonlinear spectral response, model interfering spectral responses and detect outlier data with high sensitivity.
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Sousa, Cláudia; de Winter, Lenneke; Janssen, Marcel; Vermuë, Marian H; Wijffels, René H
2012-01-01
The effect of partial oxygen pressure on growth of Neochloris oleoabundans was studied at sub-saturating light intensity in a fully-controlled stirred tank photobioreactor. At the three partial oxygen pressures tested (P(O)₂= 0.24; 0.63; 0.84 bar), the specific growth rate was 1.38; 1.36 and 1.06 day(-1), respectively. An increase of the P(CO)₂from 0.007 to 0.02 bar at P(O₂) of 0.84 bar resulted in an increase in the growth rate from 1.06 to 1.36 day(-1). These results confirm that the reduction of algal growth at high oxygen concentrations at sub-saturating light conditions is mainly caused by competitive inhibition of Rubisco. This negative effect on growth can be overcome by restoring the O(2)/CO(2) ratio by an increase in the partial carbon dioxide pressure. In comparison to general practice (P(O(2)) = 0.42 bar), working at partial O(2) pressure of 0.84 bar could reduce the energy requirement for degassing by a factor of 3-4. Copyright © 2011 Elsevier Ltd. All rights reserved.
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Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones.
Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene M; Revsbech, Niels Peter; Löscher, Carolin; Schunck, Harald; Desai, Dhwani K; Hauss, Helena; Kiko, Rainer; Holtappels, Moritz; LaRoche, Julie; Schmitz, Ruth A; Graco, Michelle I; Kuypers, Marcel M M
2015-01-01
Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein.
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Aerobic Microbial Respiration In Oceanic Oxygen Minimum Zones
Kalvelage, Tim; Lavik, Gaute; Jensen, Marlene M.; Revsbech, Niels Peter; Löscher, Carolin; Schunck, Harald; Desai, Dhwani K.; Hauss, Helena; Kiko, Rainer; Holtappels, Moritz; LaRoche, Julie; Schmitz, Ruth A.; Graco, Michelle I.; Kuypers, Marcel M. M.
2015-01-01
Oxygen minimum zones are major sites of fixed nitrogen loss in the ocean. Recent studies have highlighted the importance of anaerobic ammonium oxidation, anammox, in pelagic nitrogen removal. Sources of ammonium for the anammox reaction, however, remain controversial, as heterotrophic denitrification and alternative anaerobic pathways of organic matter remineralization cannot account for the ammonium requirements of reported anammox rates. Here, we explore the significance of microaerobic respiration as a source of ammonium during organic matter degradation in the oxygen-deficient waters off Namibia and Peru. Experiments with additions of double-labelled oxygen revealed high aerobic activity in the upper OMZs, likely controlled by surface organic matter export. Consistently observed oxygen consumption in samples retrieved throughout the lower OMZs hints at efficient exploitation of vertically and laterally advected, oxygenated waters in this zone by aerobic microorganisms. In accordance, metagenomic and metatranscriptomic analyses identified genes encoding for aerobic terminal oxidases and demonstrated their expression by diverse microbial communities, even in virtually anoxic waters. Our results suggest that microaerobic respiration is a major mode of organic matter remineralization and source of ammonium (~45-100%) in the upper oxygen minimum zones, and reconcile hitherto observed mismatches between ammonium producing and consuming processes therein. PMID:26192623
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NASA Astrophysics Data System (ADS)
Medina-Silva, Renata; de Oliveira, Rafael R.; Pivel, Maria A. G.; Borges, Luiz G. A.; Simão, Taiz L. L.; Pereira, Leandro M.; Trindade, Fernanda J.; Augustin, Adolpho H.; Valdez, Fernanda P.; Eizirik, Eduardo; Utz, Laura R. P.; Groposo, Claudia; Miller, Dennis J.; Viana, Adriano R.; Ketzer, João M. M.; Giongo, Adriana
2018-02-01
Conspicuous physicochemical vertical stratification in the deep sea is one of the main forces driving microbial diversity in the oceans. Oxygen and sunlight availability are key factors promoting microbial diversity throughout the water column. Ocean currents also play a major role in the physicochemical stratification, carrying oxygen down to deeper zones as well as moving deeper water masses up towards shallower depths. Water samples within a 50-km radius in a pockmark location of the southwestern Atlantic Ocean were collected and the prokaryotic communities from different water depths - chlorophyll maximum, oxygen minimum and deep-sea bottom (down to 1355 m) - were described. At phylum level, Proteobacteria were the most frequent in all water depths, Cyanobacteria were statistically more frequent in chlorophyll maximum zone, while Thaumarchaeota were significantly more abundant in both oxygen minimum and bottom waters. The most frequent microorganism in the chlorophyll maximum and oxygen minimum zones was a Pelagibacteraceae operational taxonomic unit (OTU). At the bottom, the most abundant genus was the archaeon Nitrosopumilus. Beta diversity analysis of the 16S rRNA gene sequencing data uncovered in this study shows high spatial heterogeneity among water zones communities. Our data brings important contribution for the characterisation of oceanic microbial diversity, as it consists of the first description of prokaryotic communities occurring in different oceanic water zones in the southwestern Atlantic Ocean.
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Simulated effects of southern hemispheric wind changes on the Pacific oxygen minimum zone
NASA Astrophysics Data System (ADS)
Getzlaff, Julia; Dietze, Heiner; Oschlies, Andreas
2016-01-01
A coupled ocean biogeochemistry-circulation model is used to investigate the impact of observed past and anticipated future wind changes in the Southern Hemisphere on the oxygen minimum zone in the tropical Pacific. We consider the industrial period until the end of the 21st century and distinguish effects due to a strengthening of the westerlies from effects of a southward shift of the westerlies that is accompanied by a poleward expansion of the tropical trade winds. Our model results show that a strengthening of the westerlies counteracts part of the warming-induced decline in the global marine oxygen inventory. A poleward shift of the trade-westerlies boundary, however, triggers a significant decrease of oxygen in the tropical oxygen minimum zone. In a business-as-usual CO2 emission scenario, the poleward shift of the trade-westerlies boundary and warming-induced increase in stratification contribute equally to the expansion of suboxic waters in the tropical Pacific.
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Pichler, Gerhard; Binder, Corinna; Avian, Alexander; Beckenbach, Elisabeth; Schmölzer, Georg M; Urlesberger, Berndt
2013-12-01
To define reference ranges for regional cerebral tissue oxygen saturation (crSO2) and regional cerebral fractional tissue oxygen extraction (cFTOE) during the first 15 minutes after birth in neonates requiring no medical support. The crSO2 was measured using near infrared spectroscopy (Invos 5100 cerebral/somatic oximeter monitor; Somanetics Corp, Troy, Michigan) during the first 15 minutes after birth for term and preterm neonates. The near infrared spectroscopy sensor was placed on the left forehead. Peripheral oxygen saturation and heart rate were continuously measured by pulse oximetry, and cFTOE was calculated. Neonates were excluded if they required any medical support. A total of 381 neonates were included: 82 term neonates after vaginal delivery, 272 term neonates after cesarean delivery, and 27 preterm neonates after cesarean delivery. In all neonates, median (10th-90th percentiles) crSO2 was 41% (23-64) at 2 minutes, 68% (45-85) at 5 minutes, 79% (65-90) at 10 minutes, and 77% (63-89) at 15 minutes of age. In all neonates, median (10th-90th percentiles) cFTOE was 33% (11-70) at 2 minutes, 21% (6-45) at 5 minutes, 15% (5-31) at 10 minutes, and 18% (7-34) at 15 minutes of age. We report reference ranges of crSO2 and cFTOE in neonates requiring no medical support during transition immediately after birth. The use of cerebral oxygenation monitoring and use of these reference ranges in neonates during transition may help to guide oxygen delivery and avoid cerebral hypo-oxygenation and hyperoxygenation. Copyright © 2013 Mosby, Inc. All rights reserved.
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First Autonomous Recording of in situ Dissolved Oxygen from Free-ranging Fish
NASA Astrophysics Data System (ADS)
Coffey, D.; Holland, K.
2016-02-01
Biologging technology has enhanced our understanding of the ecology of marine animals and has been central to identifying how oceanographic conditions drive patterns in their distribution and behavior. Among these environmental influences, there is increasing recognition of the impact of dissolved oxygen on the distribution of marine animals. Understanding of the impact of oxygen on vertical and horizontal movements would be advanced by contemporaneous in situ measurements of dissolved oxygen from animal-borne sensors instead of relying on environmental data that may not have appropriate spatial or temporal resolution. Here we demonstrate the capabilities of dissolved oxygen pop-up satellite archival tags (DO-PATs) by presenting the results from calibration experiments and trial deployments of two prototype tags on bluntnose sixgill sharks (Hexanchus griseus). The DO-PATs provided fast, accurate, and stable measurements in calibration trials and demonstrated high correlation with vertical profiles obtained via traditional ship-borne oceanographic instruments. Deployments on bluntnose sixgill sharks recorded oxygen saturations as low as 9.4% and effectively captured the oceanography of the region when compared with World Ocean Atlas 2013 values. This is the first study to use an animal-borne device to autonomously measure and record in situ dissolved oxygen saturation from non-air-breathing marine animals. The DO-PATs maintained consistency over time and yielded measurements equivalent to industry standards for environmental sampling. Acquiring contemporaneous in situ measurements of dissolved oxygen saturation alongside temperature and depth data will greatly improve our ability to investigate the spatial ecology of marine animals and make informed predictions of the impacts of global climate change. The information returned from DO-PATs is relevant not only to the study of the ecology of marine animals but will also become a useful new tool for investigating the physical structure of the oceans.
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Moerman, A; Denys, W; De Somer, F; Wouters, P F; De Hert, S G
2013-10-01
Although both pressure and flow are considered important determinants of regional organ perfusion, the relative importance of each is less established. The aim of the present study was to evaluate the impact of variations in flow, pressure, or both on cerebral and whole-body oxygen saturation. Thirty-four consenting patients undergoing elective cardiac surgery on cardiopulmonary bypass were included. Using a randomized cross-over design, four different haemodynamic states were simulated: (i) 20% flow decrease, (ii) 20% flow decrease with phenylephrine to restore baseline pressure, (iii) 20% pressure decrease with sodium nitroprusside (SNP) under baseline flow, and (iv) increased flow with baseline pressure. The effect of these changes was evaluated on cerebral (Sc(O₂)) and systemic (Sv(O₂)) oxygen saturation, and on systemic oxygen extraction ratio (OER). Data were assessed by within- and between-group comparisons. Decrease in flow was associated with a decrease in [from 63.5 (7.4) to 62.0 (8.5) %, P<0.001]. When arterial pressure was restored with phenylephrine during low flow, Sc(O₂) further decreased from 61.0 (9.7) to 59.2 (10.2) %, P<0.001. Increase in flow was associated with an increase in Sc(O₂) from 62.6 (7.7) to 63.6 (8.9) %, P=0.03, while decreases in pressure with the use of SNP did not affect Sc(O₂). Sv(O₂) was significantly lower (P<0.001) and OER was significantly higher (P<0.001) in the low flow arms. In the present elective cardiac surgery population, Sc(O₂) and Sv(O₂) were significantly lower with lower flow, regardless of systemic arterial pressure. Moreover, phenylephrine administration was associated with a reduced cerebral and systemic oxygen saturation.
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Hadjistassou, Constantinos; Moyle, Keri; Ventikos, Yiannis
2016-01-01
The advent of functional MRI in the mid-1990s has catalyzed progress pertaining to scientific discoveries in neuroscience. With the prospect of elucidating the physiological aspect of the Blood Oxygenation Level Dependent (BOLD) effect we present a computational capillary-tissue system capable of mapping venous hemoglobin saturation- a marker of the BOLD hemodynamic response. Free and facilitated diffusion and convection for hemoglobin and oxygen are considered in the radial and axial directions. Hemoglobin reaction kinetics are governed by the oxyhemoglobin dissociation curve. Brain activation, mimicked by dynamic transitions in cerebral blood velocity (CBv) and oxidative metabolism (CMRO2), is simulated by normalized changes in m = (ΔCBv/CBv)/(ΔCMRO2/CMRO2) of values 2, 3 and 4. Venous hemoglobin saturation profiles and peak oxygenation results, for m = 2, based upon a 50% and a 25% increase in CBv and CMRO2, respectively, lie within physiological limits exhibiting excellent correlation with the BOLD signal, for short-duration stimuli. Our analysis suggests basal CBv and CMRO2 values of 0.6 mm/s and 200 μmol/100g/min. Coupled CBv and CMRO2 responses, for m = 3 and m = 4, overestimate peak hemoglobin saturation, confirming the system's responsiveness to changes in hematocrit, CBv and CMRO2. Finally, factoring in neurovascular effects, we show that no initial dip will be observed unless there is a time delay in the onset of increased CBv relative to CMRO2.
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Using noninvasive NIRS to evaluate the metabolic capability of infant brain
NASA Astrophysics Data System (ADS)
Huang, Lan; Ding, Haishu; Hou, Xinling; Zhou, Congle; Lie, Zhiguang; Wang, Guangzhi; Tian, Fenghua
2005-01-01
The value of cerebral oxygenation saturation is important for optimal treatment and prognosis in neonates during perinatal period. The purpose of this study was to investigate the cerebral oxygen in newborn infants and obtain clinical characteristic parameters by using steady state spatially resolved near infrared spectroscopy. The subjects consist of 239 infants selected from two hospital. The results show that the values of regional cerebral oxygen saturation (rSO2) for preterm infants with gestational ages of 27 - 32 weeks were different from term infants and the value of rSO2 for sick term infants after treatment were better than that of before treatment. Above results suggest that the value of rSO2 may be used as a clinical parameter to assess cerebral oxygen for preterm and sick infants avoiding hypoxia.
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14 CFR 25.1443 - Minimum mass flow of supplemental oxygen.
Code of Federal Regulations, 2010 CFR
2010-01-01
...,100 cc. with a constant time interval between respirations. (d) If first-aid oxygen equipment is... minute per person for whom first-aid oxygen is required. (e) If portable oxygen equipment is installed...
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Numerical investigation of oxygen transport by hemoglobin-based carriers through microvessels.
Hyakutake, Toru; Kishimoto, Takumi
2017-12-01
The small size of hemoglobin-based oxygen carriers (HBOCs) may expand the realm of new treatment possibilities for various circulatory diseases. The parametric evaluation of HBOC performance for oxygen transport within tissue is essential for effectively characterizing its performance for each circulatory disease assessed. Thus, the overarching objective of this present study was to numerically investigate the reaction-diffusion phenomenon of oxygenated HBOCs and oxygen on tissues through microvessels. We considered dissociation rate coefficients, oxygen affinity, and diffusion coefficients due to Brownian motion as the biophysical parameters for estimating HBOC performance for oxygen transport. A two-dimensional computational domain, including vessel and tissue regions, was, therefore, accordingly assumed. It was observed that HBOC flows in a microvessel with a diameter of 25 μm and a length of 1 mm, and that the dissociated oxygen diffuses to the tissue region. The results indicated that oxyhemoglobin saturation and partial oxygen tension in a downstream region changed according to each biophysical parameter of HBOC. Moreover, the change in oxygen consumption rate in the tissue region had considerable influence on the oxyhemoglobin saturation level within the vessel. Comparison between simulation results and existing in vitro experimental data of actual HBOCs and RBC showed qualitatively good agreement. These results provide important information for the effective design of robust HBOCs in future.
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Russell, W J; James, M F
2000-12-01
Theoretically, if the cardiac output were increased in the presence of a given intrapulmonary shunt, the arterial haemoglobin oxygen saturation (SaO2) should improve as the venous oxygen extraction per ml of blood decreases. To test this hypothesis, eight pigs were subjected to one-lung ventilation and adrenaline and isoprenaline infusions used to increase the cardiac output. The mixed venous oxygen, shunt fraction and oxygen consumption were measured. With both adrenaline and isoprenaline, although there was a small rise in mixed venous oxygen content, there was a fall in SaO2. With adrenaline, the mean shunt rose from 48% to 65%, the mean oxygen consumption rose from 126 ml/min to 134 ml/min and the mean SaO2 fell from 86.9% to 82.5%. With isoprenaline, the mean shunt rose from 45% to 59%, the mean oxygen consumption rose from 121 ml/min to 137 ml/min and the mean SaO2 fell from 89.5% to 84.7%. It is concluded that potential improvement in SaO2, which might occur from a catecholamine-induced increase in mixed venous oxygen content during one-lung ventilation, is more than offset by increased shunting and oxygen consumption which reduce SaO2.
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Single-cell measurement of red blood cell oxygen affinity.
Di Caprio, Giuseppe; Stokes, Chris; Higgins, John M; Schonbrun, Ethan
2015-08-11
Oxygen is transported throughout the body by hemoglobin (Hb) in red blood cells (RBCs). Although the oxygen affinity of blood is well-understood and routinely assessed in patients by pulse oximetry, variability at the single-cell level has not been previously measured. In contrast, single-cell measurements of RBC volume and Hb concentration are taken millions of times per day by clinical hematology analyzers, and they are important factors in determining the health of the hematologic system. To better understand the variability and determinants of oxygen affinity on a cellular level, we have developed a system that quantifies the oxygen saturation, cell volume, and Hb concentration for individual RBCs in high throughput. We find that the variability in single-cell saturation peaks at an oxygen partial pressure of 2.9%, which corresponds to the maximum slope of the oxygen-Hb dissociation curve. In addition, single-cell oxygen affinity is positively correlated with Hb concentration but independent of osmolarity, which suggests variation in the Hb to 2,3-diphosphoglycerate (2-3 DPG) ratio on a cellular level. By quantifying the functional behavior of a cellular population, our system adds a dimension to blood cell analysis and other measurements of single-cell variability.
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Cunningham, Steve; Rodriguez, Aryelly; Adams, Tim; Boyd, Kathleen A; Butcher, Isabella; Enderby, Beth; MacLean, Morag; McCormick, Jonathan; Paton, James Y; Wee, Fiona; Thomas, Huw; Riding, Kay; Turner, Steve W; Williams, Chris; McIntosh, Emma; Lewis, Steff C
2015-09-12
The American Academy of Pediatrics recommends a permissive hypoxaemic target for an oxygen saturation of 90% for children with bronchiolitis, which is consistent with the WHO recommendations for targets in children with lower respiratory tract infections. No evidence exists to support this threshold. We aimed to assess whether the 90% or higher target for management of oxygen supplementation was equivalent to a normoxic 94% or higher target for infants admitted to hospital with viral bronchiolitis. We did a parallel-group, randomised, controlled, equivalence trial of infants aged 6 weeks to 12 months of age with physician-diagnosed bronchiolitis newly admitted into eight paediatric hospital units in the UK (the Bronchiolitis of Infancy Discharge Study [BIDS]). A central computer randomly allocated (1:1) infants, in varying length blocks of four and six and without stratification, to be clipped to standard oximeters (patients treated with oxygen if pulse oxygen saturation [SpO2] <94%) or modified oximeters (displayed a measured value of 90% as 94%, therefore oxygen not given until SpO2 <90%). All parents, clinical staff, and outcome assessors were masked to allocation. The primary outcome was time to resolution of cough (prespecified equivalence limits of plus or minus 2 days) in the intention-to-treat population. This trial is registered with ISRCTN, number ISRCTN28405428. Between Oct 3, and March 30, 2012, and Oct 1, and March 29, 2013, we randomly assigned 308 infants to standard oximeters and 307 infants to modified oximeters. Cough resolved by 15·0 days (median) in both groups (95% CI for difference -1 to 2) and so oxygen thresholds were equivalent. We recorded 35 serious adverse events in 32 infants in the standard care group and 25 serious adverse events in 24 infants in the modified care group. In the standard care group, eight infants transferred to a high-dependency unit, 23 were readmitted, and one had a prolonged hospital stay. In the modified care group, 12 infants were transferred to a high-dependency unit and 12 were readmitted to hospital. Recorded adverse events did not differ significantly. Management of infants with bronchiolitis to an oxygen saturation target of 90% or higher is as safe and clinically effective as one of 94% or higher. Future research should assess the benefits and risks of different oxygen saturation targets in acute respiratory infection in older children, particularly in developing nations where resources are scarce. National Institute for Health Research, Health Technology Assessment programme. Copyright © 2015 Cunningham et al. Open Access article distributed under the terms of CC BY-NC-ND. Published by Elsevier Ltd.. All rights reserved.
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Aguirre, J; Borgeat, A; Trachsel, T; Cobo Del Prado, I; De Andrés, J; Bühler, P
2014-02-01
Ischemic brain damage has been reported in healthy patients after beach chair position for surgery due to cerebral hypoperfusion. Near-infrared spectroscopy has been described as a non-invasive, continuous method to monitor cerebral oxygen saturation. However, its impact on neurobehavioral outcome comparing different anesthesia regimens has been poorly described. In this prospective, assessor-blinded study, 90 patients undergoing shoulder surgery in beach chair position following general (G-group, n=45) or regional anesthesia (R-group; n=45) were enrolled to assess the prevalence of cerebral desaturation events comparing anesthesia regimens and their impact on neurobehavioral and neurological outcome. Anesthesiologists were blinded to regional cerebral oxygen saturation values. Baseline data assessed the day before surgery included neurological and neurobehavioral tests, which were repeated the day after surgery. The baseline data for regional cerebral oxygen saturation/bispectral index and invasive blood pressure both at heart and auditory meatus levels were taken prior to anesthesia, 5 min after induction of anesthesia, 5 min after beach chair positioning, after skin incision and thereafter all 20 min until discharge. Patients in the R-group showed significantly less cerebral desaturation events (p<0.001), drops in regional cerebral oxygen saturation values (p<0.001), significantly better neurobehavioral test results the day after surgery (p<0.001) and showed a greater hemodynamic stability in the beach chair position compared to patients in the G-group. The incidence of regional cerebral oxygen desaturations seems to influence the neurobehavioral outcome. Regional anesthesia offers more stable cardiovascular conditions for shoulder surgery in beach chair position influencing neurobehavioral test results at 24h. Copyright © 2013 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Published by Elsevier España. All rights reserved.
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78 FR 1765 - Requirements for Chemical Oxygen Generators Installed on Transport Category Airplanes
Federal Register 2010, 2011, 2012, 2013, 2014
2013-01-09
... the supplemental oxygen supply can also complicate activating the oxygen flow, since that is generally... oxygen quantity requirements of Sec. 25.1443, Minimum mass flow of supplemental oxygen. E. Related...-0812; Notice No. 13-01] RIN 2120-AK14 Requirements for Chemical Oxygen Generators Installed on...
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Hou, Chen; Gheorghiu, Stefan; Huxley, Virginia H.; Pfeifer, Peter
2010-01-01
The space-filling fractal network in the human lung creates a remarkable distribution system for gas exchange. Landmark studies have illuminated how the fractal network guarantees minimum energy dissipation, slows air down with minimum hardware, maximizes the gas- exchange surface area, and creates respiratory flexibility between rest and exercise. In this paper, we investigate how the fractal architecture affects oxygen transport and exchange under varying physiological conditions, with respect to performance metrics not previously studied. We present a renormalization treatment of the diffusion-reaction equation which describes how oxygen concentrations drop in the airways as oxygen crosses the alveolar membrane system. The treatment predicts oxygen currents across the lung at different levels of exercise which agree with measured values within a few percent. The results exhibit wide-ranging adaptation to changing process parameters, including maximum oxygen uptake rate at minimum alveolar membrane permeability, the ability to rapidly switch from a low oxygen uptake rate at rest to high rates at exercise, and the ability to maintain a constant oxygen uptake rate in the event of a change in permeability or surface area. We show that alternative, less than space-filling architectures perform sub-optimally and that optimal performance of the space-filling architecture results from a competition between underexploration and overexploration of the surface by oxygen molecules. PMID:20865052
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NASA Technical Reports Server (NTRS)
1996-01-01
NASA's standard for oxygen system design, materials selection, operation, and transportation is presented. Minimum guidelines applicable to NASA Headquarters and all NASA Field Installations are contained.
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A new method for noninvasive venous blood oxygen detection.
Zhang, Xu; Zhang, Meimei; Zheng, Shengkun; Wang, Liqi; Ye, Jilun
2016-07-19
Blood oxygen saturation of vein (SvO2) is an important clinical parameter for patient monitoring. However, the existing clinical methods are invasive, expensive, which are also painful for patients. Based on light-absorption, this study describes a new noninvasive SvO2 measurement method by using external stimulation signal to generate cyclical fluctuation signal in the vein, which overcomes the low signal-to-noise ratio problem in the measurement process. In this way, the value of SvO2 can be obtained continuously in real time. The experimental results demonstrate that the method can successfully measure venous oxygen saturation by artificial addition of stimulation. Under hypoxic conditions, the system can reflect the overall decline of venous oxygen saturation better. When the results measured by the new method are compared with those measured by the invasive method, the root mean square error of the difference is 5.31 and the correlation coefficient of the difference is 0.72. The new method can be used to measure SvO2 and evaluate body oxygen consumption, and its accuracy needs improvement. Real-time and continuous monitoring can be achieved by replacing invasive method with noninvasive method, which provides more comprehensive clinical information in a timely manner and better meet the needs of clinical treatment. However, the accuracy of the new noninvasive SvO2 measurement based on light-absorption has to be further improved.
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Ionizing radiation induced degradation of salicylic acid in aqueous solution
NASA Astrophysics Data System (ADS)
Albarrán, Guadalupe; Mendoza, Edith
2018-06-01
The radiation-induced degradation of salicylic acid (SA-) in aqueous solutions (1.0 and 0.1 mmol dm-3) saturated with N2O or air or without oxygen were studied. Irradiation was carried out using a cobalt-60 source. With a 1 mmol dm-3 solution saturated with N2O a seemingly total degradation occurred at about 18 kGy, although small quantities of 2,3-dihydroxybenzoic acid, catechol and 2,5-dihydroxybenzoic acid were present at that dose at concentrations of 67, 22 and 6 μmol dm-3 respectively. Under air and when free oxygen, the three radiolytic products were present at 18.54 kGy while SA- was destroyed only to 90% and 62%, respectively. In the case of 0.1 mmol dm-3 SA- solutions, the acid was degraded at 3.5 kGy if the solution contained N2O, at 5.8 kGy in air and at 7 kGy without oxygen. The concentration of the radiolytic products increased with increasing dose and after a maximum they decreased. The oxidation was followed by measuring the chemical oxygen demand; the slopes were 0.48 and 0.11, 0.21 and 0.07, 0.15 and 0.03 mmol dm-3 kGy-1 for 1.0 and 0.10 mmol dm-3 solutions saturated with N2O or air or without oxygen, respectively.
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Bacterioplankton Populations within the Oxygen Minimum Zone of the Sargasso Sea
NASA Astrophysics Data System (ADS)
Schuler, G.; Parsons, R. J.; Johnson, R. J.
2016-02-01
Oxygen minimum zones are present throughout the world's oceans, and occur at depths between 200 to 1000m. Heterotrophic bacteria reduce the dissolved oxygen within this layer through respiration, while metabolizing falling particles. This report studied the bacterioplankton in the oxygen minimum zone at the BATS (Bermuda Atlantic Times-series Study) site from July 2014 until November 2014. Total bacterioplankton populations were enumerated through direct counts. In the transitional zone (400m-800m) of the oxygen minimum zone, a secondary bacterioplankton peak formed. This study used FISH (Fluorescent in situ hybridization) and CARD-FISH (Catalyzed Reporter Deposition-Fluorescent in situ hybridization) to enumerate specific bacterial and archaeal taxa. Crenarchaeota (including Thaumarchaeota) increased in abundance within the upper oxycline. Thaumarchaeota have the ammonia monooxygenase gene that oxidizes ammonium into nitrite in low oxygen conditions. Amplification of the amoA gene confirmed that ammonia oxidizing archaea (AOA) were present within the OMZ. Using Terminal Restriction Fragment Length Polymorphism (T-RFLP), the bacterial community structure showed high similarity based depth zones (0-80m, 160-600m, and 800-4500m). Niskin experiments determined that water collected at 800m had an exponential increase in bacterioplankton over time. While experimental design did not allow for oxygen levels to be maintained, the bacterioplankton community was predominantly bacteria with eubacteria positive cells making up 89.3% of the of the total bacterioplankton community by day 34. Improvements to the experimental design are required to determine which specific bacterial taxa caused this increase at 800m. This study suggests that there are factors other than oxygen influencing bacterioplankton populations at the BATS site, and more analysis is needed once the BATS data is available to determine the key drivers of bacterioplankton dynamics within the BATS OMZ.
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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
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How Should Oxygen Supplementation Be Guided by Pulse Oximetry in Children: Do We Know the Level?
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
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Yap, Shook H; Anania, Nicole; Alboliras, Ernerio T; Lilien, Lawrence D
2009-04-01
The newborn can experience two types of differential cyanosis (DC). The common type of DC occurs when oxygen saturation in the right hand is greater than in the foot. The second type of DC, reversed differential cyanosis (RDC), occurs when oxygen saturation is lower in the right hand than in the foot. This phenomenon is observed in transposition of the great arteries (TGA) with patent ductus arteriosis (PDA) and elevated pulmonary vascular resistance or in TGA with PDA and preductal aortic interruption or coarctation. This report describes a case of RDC not previously described involving an infant with supracardiac total anomalous pulmonary venous connection (TAPVC). In supracardiac TAPVC, RDC results from streaming of highly saturated superior vena cava (SVC) blood into the right ventricle, out the main pulmonary artery, through a PDA, and to the descending aorta, with streaming of more desaturated blood from the inferior vena cava (IVC) into the left atrium across the atrial septal defect (ASD)/foramen ovale. Therefore, as part of a neonatal examination to rule out congenital heart disease (CHD), simultaneous pre- and postductal oxygen saturations should be documented. The presence of RDC should initiate immediate full cardiac evaluation for CHD. Supracardiac TAPVC should be included in the differential diagnosis if RDC is observed.
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NASA Astrophysics Data System (ADS)
Imms, Ryan; Hu, Sijung; Azorin-Peris, Vicente; Trico, Michaël.; Summers, Ron
2014-03-01
Non-contact imaging photoplethysmography (PPG) is a recent development in the field of physiological data acquisition, currently undergoing a large amount of research to characterize and define the range of its capabilities. Contact-based PPG techniques have been broadly used in clinical scenarios for a number of years to obtain direct information about the degree of oxygen saturation for patients. With the advent of imaging techniques, there is strong potential to enable access to additional information such as multi-dimensional blood perfusion and saturation mapping. The further development of effective opto-physiological monitoring techniques is dependent upon novel modelling techniques coupled with improved sensor design and effective signal processing methodologies. The biometric signal and imaging processing platform (bSIPP) provides a comprehensive set of features for extraction and analysis of recorded iPPG data, enabling direct comparison with other biomedical diagnostic tools such as ECG and EEG. Additionally, utilizing information about the nature of tissue structure has enabled the generation of an engineering model describing the behaviour of light during its travel through the biological tissue. This enables the estimation of the relative oxygen saturation and blood perfusion in different layers of the tissue to be calculated, which has the potential to be a useful diagnostic tool.
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USDA-ARS?s Scientific Manuscript database
The effect of daily minimum dissolved oxygen concentration on growth and yield (kg/ha) of the channel catfish (Ictalurus punctatus) and the channel x blue hybrid catfish (I. punctatus female x I. furcatus male), which shared the Jubilee strain of channel catfish as the maternal parent, was evaluated...
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Vercoutere, T.L.; Mullins, H.T.; McDougall, K.; Thompson, J.B.
1987-01-01
Distribution, abundance, and diversity of terrigenous, authigenous, and biogenous material provide evidence of the effect of bottom currents and oxygen minimum zone (OMZ) on continental slope sedimentation offshore central California. Three major OMZ facies are identified, along the upper and lower edges of OMZ and one at its core.-from Authors
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Hyperspectral near infrared spectroscopy assessment of the brain during hypoperfusion
NASA Astrophysics Data System (ADS)
Nguyen, Thu N.; Wu, Wen; Woldemichael, Ermias; Toronov, Vladislav; Lin, Steve
2018-02-01
Two-thirds of out-of-hospital cardiac arrest patients, who survive to hospital admission, die in the hospital from neurological injuries related to cerebral hypoperfusion. Hyperspectral near infrared spectroscopy (hNIRS) is a noninvasive technique that measures the major chromophores in the brain, such as oxygenated hemoglobin, deoxygenated hemoglobin and cytochrome C oxidase ([CCO]), an intracellular marker of oxygen consumption. We have demonstrated that hNIRS is feasible and can detect changes in cerebral oxygenation and metabolism in patients undergoing transcatheter aortic valve insertion (TAVI) - a procedure that temporarily induces sudden hypotension and hypoperfusion that mimics cardiac arrest. Using multi-distance hNIRS, we found that while measured regional oxygen saturation (rSO2) changes resulted mainly from the extra-cerebral tissues, [CCO] changes during cardiac arrests occurred mainly in the brains of patients. We also applied the hNIRS algorithm based on the "2-layer model" to the data to measure cerebral oxygen saturation and [CCO] in patients during the procedure.
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Oxygen isotopes as a tool to quantify reservoir-scale CO2 pore-space saturation
NASA Astrophysics Data System (ADS)
Serno, Sascha; Flude, Stephanie; Johnson, Gareth; Mayer, Bernard; Boyce, Adrian; Karolyte, Ruta; Haszeldine, Stuart; Gilfillan, Stuart
2017-04-01
Structural and residual trapping of carbon dioxide (CO2) are two key mechanisms of secure CO2 storage, an essential component of Carbon Capture and Storage technology [1]. Estimating the amount of CO2 that is trapped by these two mechanisms is a vital requirement for accurately assessing the secure CO2 storage capacity of a formation, but remains a key challenge. Recent field [2,3] and laboratory experiment studies [4] have shown that simple and relatively inexpensive measurements of oxygen isotope ratios in both the injected CO2 and produced water can provide an assessment of the amount of CO2 that is stored by these processes. These oxygen isotope assessments on samples obtained from observation wells provide results which are comparable to other geophysical techniques. In this presentation, based on the first comprehensive review of oxygen isotope ratios measured in reservoir waters and CO2 from global CO2 injection projects, we will outline the advantages and potential limitations of using oxygen isotopes to quantify CO2 pore-space saturation. We will further summarise the currently available information on the oxygen isotope composition of captured CO2. Finally, we identify the potential issues in the use of the oxygen isotope shifts in the reservoir water from baseline conditions to estimate accurate saturations of the pore space with CO2, and suggest how these issues can be reduced or avoided to provide reliable CO2 pore-space saturations on a reservoir scale in future field experiments. References [1] Scott et al., (2013) Nature Climate Change, Vol. 3, 105-111 doi:10.1038/nclimate1695 [2] Johnson et al., (2011) Chemical Geology, Vol. 283, 185-193 http://dx.doi.org/10.1016/j.ijggc.2016.06.019 [3] Serno et al., (2016) IJGGC, Vol. 52, 73-83 http://dx.doi.org/10.1016/j.ijggc.2016.06.019 [4] Johnson et al., (2011) Applied Geochemistry, Vol. 26 (7) 1184-1191 http://dx.doi.org/10.1016/j.apgeochem.2011.04.007
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Wilkinson, P L
1979-06-01
Assessing and modifying oxygen transport are major parts of ICU patient management. Determination of base excess, blood oxygen saturation and content, dead space ventilation, and P50 helps in this management. A program is described for determining these variables using a T1 59 programmable calculator and PC 100A printer. Each variable can be independently calculated without running the whole program. The calculator-printer's small size, low cost, and hard copy printout make it a valuable and versatile tool for calculating physiological variables. The program is easily entered by an stored on magnetic card, and prompts the user to enter the appropriate variables, making is easy to run by untrained personnel.
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Pop goes the O2: a case of popper-induced methaemoglobinamia
McCabe, Aileen; McCann, Brendan; Kelly, Paul
2012-01-01
A 39-year-old man presented to the emergency department after falling downstairs after he consumed a large quantity of alcohol. On examination, he had altered mental state (GCS 14), central cyanosis and low oxygen saturation of 86%, despite 100% oxygen being administered. His arterial blood gas confirmed diagnosis of methaemoglobinaemia with a methaemoglobin percentage of 14.08. He was treated successfully with methylthioninium chloride. The patient later admitted to use of recreational poppers (amyl nitrates) the previous evening. The emergency physician is challenged by the presentation of a patient with altered mental state and unexplained low oxygen saturation with concurrent alcohol intoxication but must have a high index of suspicion for methaemoglobinaemia particularly with a history of recreational drug ingestion. PMID:23175012
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Sousa, Claudia; Valev, Dimitar; Vermuë, Marian H; Wijffels, Rene H
2013-08-01
In tubular photobioreactors micro-algae continuously experience dynamically changing oxygen and light conditions when circulating from the solar receiver to the dark degasser. These changes in oxygen concentration and light were simulated in a CSTR using sub-saturating light intensity. Elongation of the residence time in the solar receiver from 30 to 300 min was also investigated. Specific growth rates measured at constant low oxygen concentration PO2=0.21 bar were; 1.14 ± 0.06 day(-1) using continuous light 0.80 ± 0.16 day(-1) with 30 min light and 1.09 ± 0.05 day(-1) with 300 min light. The effect of dynamically changing oxygen concentrations from PO2=0.21 to 0.63 bar followed by degassing resulted in similar specific growth rates. The exposure of the algae cells to dark periods in the degasser has a bigger negative impact than the temporary exposure to accumulating oxygen concentrations in the solar receiver. This shows that considerable energy savings for degassing are possible. Copyright © 2013 Elsevier Ltd. All rights reserved.
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Use of biomedical photonics in gynecological surgery: a uterine transplantation model
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
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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.
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Eren, Baran; Kersell, Heath; Weatherup, Robert S; Heine, Christian; Crumlin, Ethan J; Friend, Cynthia M; Salmeron, Miquel B
2018-01-18
Using ambient pressure X-ray photoelectron spectroscopy (APXPS) and high pressure scanning tunneling microscopy (HPSTM), we show that in equilibrium with 0.01-0.2 Torr of methanol vapor, at room temperature, the Cu(100) surface is covered with methoxy species forming a c(2 × 2) overlayer structure. In contrast, no methoxy is formed if the surface is saturated with an ordered oxygen layer, even when the methanol pressure is 0.2 Torr. At oxygen coverages below saturation, methanol dissociates and reacts with the atomic oxygen, producing methoxy and formate on the surface, and formaldehyde that desorbs to the gas phase. Unlike the case of pure carbon monoxide and carbon dioxide, methanol does not induce the restructuring of the Cu(100) surface. These results provide insight into catalytic anhydrous production of aldehydes.
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Kraemer, Robert; Sorg, Heiko; Forstmeier, Vinzent; Knobloch, Karsten; Liodaki, Eirini; Stang, Felix Hagen; Mailaender, Peter; Kisch, Tobias
2016-12-01
Elucidation of the precise mechanisms and therapeutic options of extracorporeal shock wave therapy (ESWT) is only at the beginning. Although immediate real-time effects of ESWT on cutaneous hemodynamics have recently been described, the dose response to different ESWT energies in cutaneous microcirculation has never been examined. Thirty-nine Sprague-Dawley rats were randomly assigned to three groups that received either focused high-energy shock waves (group A: total of 1000 impulses, 10 J) to the lower leg of the hind limb, focused low-energy shock waves (group B: total of 300 impulses, 1 J) or placebo shock wave treatment (group C: 0 impulses, 0 J) using a multimodality shock wave delivery system (Duolith SD-1 T-Top, Storz Medical, Tägerwilen, Switzerland). Immediate microcirculatory effects were assessed with the O2C (oxygen to see) system (LEA Medizintechnik, Giessen, Germany) before and for 20 min after application of ESWT. Cutaneous tissue oxygen saturation increased significantly higher after high-energy ESWT than after low-energy and placebo ESWT (A: 29.4% vs. B: 17.3% vs. C: 3.3%; p = 0.003). Capillary blood velocity was significantly higher after high-energy ESWT and lower after low-energy ESWT versus placebo ESWT (group A: 17.8% vs. group B: -22.1% vs. group C: -5.0%, p = 0.045). Post-capillary venous filling pressure was significantly enhanced in the high-energy ESWT group in contrast to the low-energy ESWT and placebo groups (group A: 25% vs. group B: 2% vs. group C: -4%, p = 0.001). Both high-energy and low-energy ESWT affect cutaneous hemodynamics in a standard rat model. High-energy ESWT significantly increases parameters of cutaneous microcirculation immediately after application, resulting in higher tissue oxygen saturation, venous filling pressure and blood velocity, which suggests higher tissue perfusion with enhanced oxygen saturation, in contrast to low-energy as well as placebo ESWT. Low-energy ESWT also increased tissue oxygen saturation, albeit to a lower extent, and decreases both blood velocity and venous filling pressure. Low-energy ESWT reduced tissue perfusion, but improved oxygen saturation immediately after the application. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.
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Imaging putative foetal cerebral blood oxygenation using susceptibility weighted imaging (SWI).
Yadav, Brijesh Kumar; Krishnamurthy, Uday; Buch, Sagar; Jella, Pavan; Hernandez-Andrade, Edgar; Yeo, Lami; Korzeniewski, Steven J; Trifan, Anabela; Hassan, Sonia S; Haacke, E Mark; Romero, Roberto; Neelavalli, Jaladhar
2018-05-01
To evaluate the magnetic susceptibility, ∆χ v , as a surrogate marker of venous blood oxygen saturation, S v O 2 , in second- and third-trimester normal human foetuses. Thirty-six pregnant women, having a mean gestational age (GA) of 31 2/7 weeks, underwent magnetic resonance imaging (MRI). Susceptibility-weighted imaging (SWI) data from the foetal brain were acquired. ∆χ v of the superior sagittal sinus (SSS) was quantified using MR susceptometry from the intra-vascular phase measurements. Assuming the magnetic property of foetal blood, ∆χ do , is the same as that of adult blood, S v O 2 was derived from the measured Δχ v . The variation of ∆χ v and S v O 2 , as a function of GA, was statistically evaluated. The mean ∆χ v in the SSS in the second-trimester (n = 8) and third-trimester foetuses (n = 28) was found to be 0.34± 0.06 ppm and 0.49 ±0.05 ppm, respectively. Correspondingly, the derived S v O 2 values were 69.4% ±3.27% and 62.6% ±3.25%. Although not statistically significant, an increasing trend (p = 0.08) in Δχ v and a decreasing trend (p = 0.22) in S v O 2 with respect to advancing gestation was observed. We report cerebral venous blood magnetic susceptibility and putative oxygen saturation in healthy human foetuses. Cerebral oxygen saturation in healthy human foetuses, despite a slight decreasing trend, does not change significantly with advancing gestation. • Cerebral venous magnetic susceptibility and oxygenation in human foetuses can be quantified. • Cerebral venous oxygenation was not different between second- and third-trimester foetuses. • Foetal cerebral venous oxygenation does not change significantly with advancing gestation.
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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.
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Kamran, Anam; Chia, Elisa; Tobin, Claire
2018-02-01
Oxygen is a widely used drug in the hospital setting. However, international audits suggest that oxygen administration practices are often not compliant with prescribed standards. This can place patients at risk and cause serious adverse events. To analyse data related to recent practices of oxygen prescription and administration at Royal Perth Hospital (RPH), Western Australia. The results of this audit aim to guide further research on possible interventional studies implementing key solutions. All patients who received care in the Acute Medical Unit at RPH between 1 September and 14 September 2015 were included in this audit. Patients who were given supplemental oxygen during their admission were selected for further review of records. Appropriate medically indicated target oxygen saturations for each patient were judged under consultation with a respiratory specialist. A total of 65 patients received oxygen supplementation within the study period; 36 of these patients (55.4%) had target oxygen saturations prescribed by doctors, and 25% of the prescribed targets were judged to be inappropriate. In total, 49 patients (75.4%) were exposed to a potential risk from oxygen therapy due to prescription error and/or delivery error. A real risk was identified in 19 patients (29.2%) as they received oxygen at levels outside their appropriate medically indicated target range. The current practices of oxygen prescription and administration within RPH are suboptimal. Patients are placed at risk of oxygen toxicity due to deviation from oxygen prescription guidelines. © 2017 Royal Australasian College of Physicians.
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Single-cell measurement of red blood cell oxygen affinity
Di Caprio, Giuseppe; Stokes, Chris; Higgins, John M.; Schonbrun, Ethan
2015-01-01
Oxygen is transported throughout the body by hemoglobin (Hb) in red blood cells (RBCs). Although the oxygen affinity of blood is well-understood and routinely assessed in patients by pulse oximetry, variability at the single-cell level has not been previously measured. In contrast, single-cell measurements of RBC volume and Hb concentration are taken millions of times per day by clinical hematology analyzers, and they are important factors in determining the health of the hematologic system. To better understand the variability and determinants of oxygen affinity on a cellular level, we have developed a system that quantifies the oxygen saturation, cell volume, and Hb concentration for individual RBCs in high throughput. We find that the variability in single-cell saturation peaks at an oxygen partial pressure of 2.9%, which corresponds to the maximum slope of the oxygen–Hb dissociation curve. In addition, single-cell oxygen affinity is positively correlated with Hb concentration but independent of osmolarity, which suggests variation in the Hb to 2,3-diphosphoglycerate (2–3 DPG) ratio on a cellular level. By quantifying the functional behavior of a cellular population, our system adds a dimension to blood cell analysis and other measurements of single-cell variability. PMID:26216973
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Optical sensor technology for a noninvasive continuous monitoring of blood components
NASA Astrophysics Data System (ADS)
Kraitl, Jens; Timm, Ulrich; Lewis, Elfed; Ewald, Hartmut
2010-02-01
NIR-spectroscopy and Photoplethysmography (PPG) is used for a measurement of blood components. The absorptioncoefficient of blood differs at different wavelengths. This fact is used to calculate the optical absorbability characteristics of blood which is yielding information about blood components like hemoglobin (Hb), carboxyhemoglobin (CoHb) and arterial oxygen saturation (SpO2). The measured PPG time signals and the ratio between the peak to peak pulse amplitudes are used for a measurement of these parameters. Hemoglobin is the main component of red blood cells. The primary function of Hb is the transport of oxygen from the lungs to the tissue and carbon dioxide back to the lungs. The Hb concentration in human blood is an important parameter in evaluating the physiological status of an individual and an essential parameter in every blood count. Currently, invasive methods are used to measure the Hb concentration, whereby blood is taken from the patient and subsequently analyzed. Apart from the discomfort of drawing blood samples, an added disadvantage of this method is the delay between the blood collection and its analysis, which does not allow real time patient monitoring in critical situations. A noninvasive method allows pain free continuous on-line patient monitoring with minimum risk of infection and facilitates real time data monitoring allowing immediate clinical reaction to the measured data.
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Lücker, Adrien; Secomb, Timothy W.; Weber, Bruno; Jenny, Patrick
2018-01-01
Capillary dysfunction impairs oxygen supply to parenchymal cells and often occurs in Alzheimer's disease, diabetes and aging. Disturbed capillary flow patterns have been shown to limit the efficacy of oxygen extraction and can be quantified using capillary transit time heterogeneity (CTH). However, the transit time of red blood cells (RBCs) through the microvasculature is not a direct measure of their capacity for oxygen delivery. Here we examine the relation between CTH and capillary outflow saturation heterogeneity (COSH), which is the heterogeneity of blood oxygen content at the venous end of capillaries. Models for the evolution of hemoglobin saturation heterogeneity (HSH) in capillary networks were developed and validated using a computational model with moving RBCs. Two representative situations were selected: a Krogh cylinder geometry with heterogeneous hemoglobin saturation (HS) at the inflow, and a parallel array of four capillaries. The heterogeneity of HS after converging capillary bifurcations was found to exponentially decrease with a time scale of 0.15–0.21 s due to diffusive interaction between RBCs. Similarly, the HS difference between parallel capillaries also drops exponentially with a time scale of 0.12–0.19 s. These decay times are substantially smaller than measured RBC transit times and only weakly depend on the distance between microvessels. This work shows that diffusive interaction strongly reduces COSH on a small spatial scale. Therefore, we conclude that CTH influences COSH yet does not determine it. The second part of this study will focus on simulations in microvascular networks from the rodent cerebral cortex. Actual estimates of COSH and CTH will then be given. PMID:29755365
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Samareh Fekri, Mitra; Hashemi-Bajgani, Seyed-Mehdi; Naghibzadeh-Tahami, Ahmad; Arabnejad, Fateme
2017-01-01
Chronic obstructive pulmonary disease (COPD) is one of the most important causes of morbidity and mortality worldwide. The complications of COPD are numerous, and cognitive impairment is one of the most common complications that relates to mortality and morbidity directly. The present study was conducted with the aim of evaluating the prevalence of cognitive impairment in patients with COPD in comparison to normal individuals. In this case-control study, 87 patients with COPD, whose diagnoses were confirmed by a pulmonologist based on the spirometry test findings, were included. The mini-mental state examination (MMSE) questionnaire was administered for assessing the cognitive impairment. Arterial oxygen saturation was measured. The MMSE questionnaires were administered to 60 healthy, age-and-sex-matched individuals without a history of myocardial infarction or cerebrovascular infarction, and their arterial oxygen saturations were measured. The data were analyzed using the SPSS (version 20) software. In the case group, 42 patients (48.27%) had no cognitive impairment, 39 (44.82%) had mild, and 6 (6.89%) had moderate cognitive impairment. In the control group, 38 (63.33%) had no cognitive impairment, 20 (33.33%) mild and 2 (3.33 %) moderate cognitive impairment. There were significant relationships between the cognitive impairment and arterial oxygen saturation, severity of COPD, and higher age. The prevalence of cognitive impairment was 51.71% in the case group and 36.66% in the control group. According the results of the present study, COPD increased the risk of cognitive impairment significantly and is related to the severity of COPD, arterial oxygen saturation, and higher age.
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Lücker, Adrien; Secomb, Timothy W; Weber, Bruno; Jenny, Patrick
2018-01-01
Capillary dysfunction impairs oxygen supply to parenchymal cells and often occurs in Alzheimer's disease, diabetes and aging. Disturbed capillary flow patterns have been shown to limit the efficacy of oxygen extraction and can be quantified using capillary transit time heterogeneity (CTH). However, the transit time of red blood cells (RBCs) through the microvasculature is not a direct measure of their capacity for oxygen delivery. Here we examine the relation between CTH and capillary outflow saturation heterogeneity (COSH), which is the heterogeneity of blood oxygen content at the venous end of capillaries. Models for the evolution of hemoglobin saturation heterogeneity (HSH) in capillary networks were developed and validated using a computational model with moving RBCs. Two representative situations were selected: a Krogh cylinder geometry with heterogeneous hemoglobin saturation (HS) at the inflow, and a parallel array of four capillaries. The heterogeneity of HS after converging capillary bifurcations was found to exponentially decrease with a time scale of 0.15-0.21 s due to diffusive interaction between RBCs. Similarly, the HS difference between parallel capillaries also drops exponentially with a time scale of 0.12-0.19 s. These decay times are substantially smaller than measured RBC transit times and only weakly depend on the distance between microvessels. This work shows that diffusive interaction strongly reduces COSH on a small spatial scale. Therefore, we conclude that CTH influences COSH yet does not determine it. The second part of this study will focus on simulations in microvascular networks from the rodent cerebral cortex. Actual estimates of COSH and CTH will then be given.
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Paarmann, Hauke; Heringlake, Matthias; Heinze, Hermann; Hanke, Thorsten; Sier, Holger; Karsten, Jan; Schön, Julika
2012-03-01
Transapical transcatheter aortic valve implantation (TA-TAVI) is increasingly used to treat aortic valve stenosis in high-risk patients. Mixed venous oxygen saturation (SvO(2)) is still the 'gold standard' for the determination of the systemic oxygen delivery to consumption ratio in cardiac surgery patients. Recent data suggest that regional cerebral oxygen saturation (rScO(2)) determined by near-infrared spectroscopy is closely related to SvO(2). The present study compares rScO(2) and SvO(2) in patients undergoing TA-TAVI. n = 20 cardiac surgery patients scheduled for TA-TAVI were enrolled in this prospective observational study. SvO(2) and rScO(2) were determined at predefined time points during the procedure. Correlation and Bland-Altman analysis of the complete data set showed a correlation coefficient of r(2 )= 0.7 between rScO(2) and SvO(2) (P < 0.0001), a mean difference (bias) of 5.8 with limits of agreement (1.96 SD) of -6.8 to 18.3% and a percentage error of 17.5%. At all predefined time points correlation was moderate (r(2 )= 0.50) to close (r = 0.84), and the percentage error was <24%. RScO(2) determined by near-infrared spectroscopy is correlated to SvO(2) during varying haemodynamic conditions in patients undergoing TA-TAVI. This suggests that rScO(2) is reflective not only of the cerebral, but also of the systemic oxygen balance.
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The Extended Oxygen Window Concept for Programming Saturation Decompressions Using Air and Nitrox
Kot, Jacek; Sicko, Zdzislaw
2015-01-01
Saturation decompression is a physiological process of transition from one steady state, full saturation with inert gas at pressure, to another one: standard conditions at surface. It is defined by the borderline condition for time spent at a particular depth (pressure) and inert gas in the breathing mixture (nitrogen, helium). It is a delicate and long lasting process during which single milliliters of inert gas are eliminated every minute, and any disturbance can lead to the creation of gas bubbles leading to decompression sickness (DCS). Most operational procedures rely on experimentally found parameters describing a continuous slow decompression rate. In Poland, the system for programming of continuous decompression after saturation with compressed air and nitrox has been developed as based on the concept of the Extended Oxygen Window (EOW). EOW mainly depends on the physiology of the metabolic oxygen window—also called inherent unsaturation or partial pressure vacancy—but also on metabolism of carbon dioxide, the existence of water vapor, as well as tissue tension. Initially, ambient pressure can be reduced at a higher rate allowing the elimination of inert gas from faster compartments using the EOW concept, and maximum outflow of nitrogen. Then, keeping a driving force for long decompression not exceeding the EOW allows optimal elimination of nitrogen from the limiting compartment with half-time of 360 min. The model has been theoretically verified through its application for estimation of risk of decompression sickness in published systems of air and nitrox saturation decompressions, where DCS cases were observed. Clear dose-reaction relation exists, and this confirms that any supersaturation over the EOW creates a risk for DCS. Using the concept of the EOW, 76 man-decompressions were conducted after air and nitrox saturations in depth range between 18 and 45 meters with no single case of DCS. In summary, the EOW concept describes physiology of decompression after saturation with nitrogen-based breathing mixtures. PMID:26111113
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Quadriceps oxygenation changes during walking and running on a treadmill
NASA Astrophysics Data System (ADS)
Quaresima, Valentina; Pizzi, Assunta; De Blasi, Roberto A.; Ferrari, Adriano; de Angelis, Marco; Ferrari, Marco
1995-04-01
Vastus lateralis muscle oxygenation was investigated on volunteers as well as muscular dystrophy patients during a walking test, and on volunteers during a free running by a continuous wave near infrared instrument. The data were analyzed using an oxygenation index independent on pathlength changes. Walking did not significantly affect the oxygenation of volunteers and patients. A relative deoxygenation was found only during free running indicating an unbalance between oxygen supply and tissue oxygen extraction. Preliminary measurements of exercising muscle oxygen saturation were performed by a 110 MHz frequency-domain, multisource instrument.
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NASA Astrophysics Data System (ADS)
Gareau, Daniel S.; Truffer, Frederic; Perry, Kyle; Pham, Thai; Enestvedt, C. Kristian; Dolan, James; Hunter, John G.; Jacques, Steven L.
2010-11-01
Anastomotic complication is a major morbidity associated with esophagectomy. Gastric ischemia after conduit creation contributes to anastomotic complications, but a reliable method to assess oxygenation in the gastric conduit is lacking. We hypothesize that fiber optic spectroscopy can reliably assess conduit oxygenation, and that intraoperative gastric ischemia will correlate with the development of anastomotic complications. A simple optical fiber probe spectrometer is designed for nondestructive laparoscopic measurement of blood content and hemoglobin oxygen saturation in the stomach tissue microvasculature during human esophagectomies. In 22 patients, the probe measured the light transport in stomach tissue between two fibers spaced 3-mm apart (500- to 650-nm wavelength range). The stomach tissue site of measurement becomes the site of a gastroesophageal anastamosis following excision of the cancerous esophagus and surgical ligation of two of the three gastric arteries that provide blood perfusion to the anastamosis. Measurements are made at each of five steps throughout the surgery. The resting baseline saturation is 0.51+/-0.15 and decreases to 0.35+/-0.20 with ligation. Seven patients develop anastomotic complications, and a decreased saturation at either of the last two steps (completion of conduit and completion of anastamosis) is predictive of complication with a sensitivity of 0.71 when the specificity equaled 0.71.
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Wozniak, Madeline; Arnell, Kathy; Brown, Melissa; Gonzales, Sarah; Lazarus, Danielle; Rich, Wade; Katheria, Anup
2018-04-01
A duration of 30 seconds has been shown to improve the success rate of intubation attempts without any decompensation. There is limited data regarding the detrimental effects of prolonged intubation attempts in preterm infants. The aim was to determine the effect of prolonged intubation attempts on heart rate and oxygen saturation in preterm infants. We retrospectively reviewed videos and physiologic data collected during delivery room (DR) resuscitations. Infants who had a functioning pulse oximeter at the time of intubation in the delivery room were analyzed using video and analog recordings. The duration of the intubation attempt was defined as the time the laryngoscope blade was in the infant's mouth. Prolonged intubations were defined as intubations over 30 seconds. Baseline heart rate and saturations were defined as the heart rate and saturation immediately prior to the intubation attempt. Video recording was used to determine time laryngoscope was in the mouth, what other procedures were performed, and whether there was recovery between attempts. Analog data including heart rate, airway pressure and saturation was also recorded. There were 52 intubation attempts in 28 infants. The median (IQR) birth weight and gestational age were 795 (705, 972) grams and 25 (25, 27) weeks. The duration of an intubation attempt was 35 (27, 46) seconds with number of attempts 2 (1, 2). There were 34 intubation attempts greater than 30 seconds (prolonged group) and 18 attempts less than or equal to 30 seconds (short group). Longer attempts did not affect intubation success (successful 34 [25,37] seconds vs. unsuccessful 41[29, 53] seconds; P=0.05). Infants in the prolonged group had a greater decrease in oxygen saturation percentage from baseline (5±8 percent, short intubation group and 13±27 prolonged intubation group; P=0.004). There was also a significant decrease in heart rate beats per minute between the two groups (6±9 in the short intubation group and 23±29 prolonged group; P=0.004). The currently recommended guideline by the Neonatal Resuscitation Program limiting intubation attempts to less than 30 seconds is supported by stable oxygen saturations and heart rate. Prolonging the intubation more than 30 seconds leads to greater hypoxia and may contribute to increased neonatal morbidity, with no effect on success rate.
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Domenici, Paolo; Ferrari, R Silvana; Steffensen, John F; Batty, Robert S
2002-10-22
The effect of progressive hypoxia on the structure and dynamics of herring (Clupea harengus) schools in laboratory conditions was investigated. The length, width and depth of schools of about 20 individuals were measured from video recordings to test the hypothesis that during hypoxia fish schools change their shape and volume. School shape (calculated as the ratios of length/depth, width/depth and length/width) did not change significantly during hypoxia. School length, width, depth, area and volume were all significantly increased at 20% oxygen saturation. Volume, area and width were more sensitive to hypoxia; volume and width were also increased at 25% and area at 30% oxygen saturation. The degree of position changing (shuffling) of individuals within the school was also analysed. Shuffling in normoxia was observed to occur largely through 'O-turn' manoeuvres, a 360( degrees )turn executed laterally to the school that allowed fishes in the front to move to the back. O-turn frequency during normoxia was 0.69 O-turns fish(-1) min(-1) but significantly decreased with hypoxia to 0.37 O-turns fish(-1) min(-1) at 30% oxygen saturation. Shuffling was also investigated by measuring the persistence time of individual herring in leading positions (i.e. the first half of the school). No significant changes occurred during hypoxia, indicating that the decrease in O-turn frequency does not affect shuffling rate during hypoxia, and that position shuffling in hypoxic conditions is mainly due to overtaking or falling back by individual fishes. School integrity and positional dynamics are the outcome of trade-offs among a number of biotic factors, such as food, predator defence, mating behaviour and various physical factors that may impose certain limits. Among these, our results indicate that oxygen level modulates schooling behaviour. Oxygen alters whole-school parameters at oxygen saturation values that can be encountered by herring in the field, indicating that oxygen availability is an important factor in the trade-offs that determine school volume. An increase in school volume in the wild may increase the oxygen available to each individual. However, shuffling rate is not affected by hypoxia, indicating that the internal dynamics of positioning is the result of the balance of other factors, for example related to the nutritional state of each individual fish as suggested by previous studies.
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(I Can’t Get No) Saturation: A simulation and guidelines for sample sizes in qualitative research
2017-01-01
I explore the sample size in qualitative research that is required to reach theoretical saturation. I conceptualize a population as consisting of sub-populations that contain different types of information sources that hold a number of codes. Theoretical saturation is reached after all the codes in the population have been observed once in the sample. I delineate three different scenarios to sample information sources: “random chance,” which is based on probability sampling, “minimal information,” which yields at least one new code per sampling step, and “maximum information,” which yields the largest number of new codes per sampling step. Next, I use simulations to assess the minimum sample size for each scenario for systematically varying hypothetical populations. I show that theoretical saturation is more dependent on the mean probability of observing codes than on the number of codes in a population. Moreover, the minimal and maximal information scenarios are significantly more efficient than random chance, but yield fewer repetitions per code to validate the findings. I formulate guidelines for purposive sampling and recommend that researchers follow a minimum information scenario. PMID:28746358
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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.
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Woods, A M; Queen, J S; Lawson, D
1991-12-01
Strenuous expulsive efforts involving sequential Valsalva maneuvers may result in maternal hypoxemia during the second stage of labor. Pulse oximetry has been used to assess oxygen saturation in laboring parturients, and this study was undertaken to evaluate the performance of the pulse oximeter (Nellcor) during the Valsalva maneuver. In both pregnant patients and nonpregnant volunteers, there were consistent interruptions in the transmission of oxygen saturation data during the Valsalva maneuver. To determine the physiologic events associated with this monitoring interruption, occlusive venous impedance plethysmographs and pulse volume amplitude recordings were obtained in volunteers performing the Valsalva maneuver. A marked decrease in pulse volume amplitude was noted, which adversely affected the oximeter's ability to distinguish physiologic arterial pulsations from background noise. Each Valsalva maneuver was associated with abrupt and transient changes in peripheral vascular volumes, thus presenting the oximeter with a rapidly changing signal for analysis that violated predetermined software criteria for pulse uniformity and caused an interruption in data transmission. The authors conclude that the Valsalva maneuver interferes with the ability of pulse oximeter technology to provide useful oxygen saturation data.
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Carbon dioxide narcosis due to inappropriate oxygen delivery: a case report.
Herren, Thomas; Achermann, Eva; Hegi, Thomas; Reber, Adrian; Stäubli, Max
2017-07-28
Oxygen delivery to patients with chronic obstructive pulmonary disease may be challenging because of their potential hypoxic ventilatory drive. However, some oxygen delivery systems such as non-rebreathing face masks with an oxygen reservoir bag require high oxygen flow for adequate oxygenation and to avoid carbon dioxide rebreathing. A 72-year-old Caucasian man with severe chronic obstructive pulmonary disease was admitted to the emergency department because of worsening dyspnea and an oxygen saturation of 81% measured by pulse oximetry. Oxygen was administered using a non-rebreathing mask with an oxygen reservoir bag attached. For fear of removing the hypoxic stimulus to respiration the oxygen flow was inappropriately limited to 4L/minute. The patient developed carbon dioxide narcosis and had to be intubated and mechanically ventilated. Non-rebreathing masks with oxygen reservoir bags must be fed with an oxygen flow exceeding the patient's minute ventilation (>6-10 L/minute.). If not, the amount of oxygen delivered will be too small to effectively increase the arterial oxygen saturation. Moreover, the risk of carbon dioxide rebreathing dramatically increases if the flow of oxygen to a non-rebreathing mask is lower than the minute ventilation, especially in patients with chronic obstructive pulmonary disease and low tidal volumes. Non-rebreathing masks (with oxygen reservoir bags) must be used cautiously by experienced medical staff and with an appropriately high oxygen flow of 10-15 L/minute. Nevertheless, arterial blood gases must be analyzed regularly for early detection of a rise in partial pressure of carbon dioxide in arterial blood in patients with chronic obstructive pulmonary disease and a hypoxic ventilatory drive. These patients are more safely managed using a nasal cannula with an oxygen flow of 1-2L/minute or a simple face mask with an oxygen flow of 5L/minute.
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Oxygen and Temperature Effects on Vertically Migrating Animals in Oxygen Minimum Zones
NASA Astrophysics Data System (ADS)
Seibel, B.
2016-02-01
Large populations of oceanic nekton and zooplankton undergo daily migrations from shallow water at night to depths greater than 200 m during the daytime. In some regions, these migrations cross extreme gradients of temperature, oxygen and carbon dioxide. Oxygen minimum zones (OMZs) are extensive and characterized by deep-water (100-800 m) oxygen partial pressures that would be lethal to most marine organisms, yet are tolerated by vertical migrators. Climate change is predicted to further deplete oxygen, and measurable reductions in oxygen have already been documented in some regions. Increases in shallow water temperature and carbon dioxide are occurring simultaneously. Oxygen levels and temperature are important drivers of biodiversity and distribution, and documented changes in community structure and function are reportedly associated with OMZ expansion and warming. Here I answer fundamental questions concerning zooplankton distributions, adaptations, and functions in oxygen minimum zones. In particular I report that metabolic suppression is a common strategy that facilitates diel occupancy of extreme hypoxia in many oceanic taxa. Anaerobic metabolic pathways play a minimal role in compensating for reduced aerobic ATP production. Numerous epigenetic mechanisms lead to reductions in energetically costly cellular processes, such as transcription and translation. Total metabolism is reduced by 50% or more during exposure to levels of hypoxia that characterize the daytime habitat for most vertically-migrating zooplankton. I further show that many migrators approach their upper thermal maximum in shallow water at night. Thus expanding OMZs and global warming may together compress the habitable depth range for many species.
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Christou, Kostas; Markoulis, Nikolaos; Moulas, Anargyros N; Pastaka, Chaido; Gourgoulianis, Kostantinos I
2003-09-01
Obstructive sleep apnea syndrome (OSA) is accompanied by oxygen desaturation and arousal from sleep. Free oxygen radicals are highly reactive molecules which could be produced by the OSA phenomenon of hypoxia/reoxygenation: cyclical alterations of arterial oxygen saturation with oxygen desaturation developing in response to apneas followed by resumption of oxygen saturation during hyperventilation. On the basis of these considerations, it was hypothesized that OSA may be linked to increased oxidative stress. Twenty-six participants gave an interview during which a physician asked them about their age, smoking habits, and symptoms such as excessive daytime sleepiness and snoring. Physical examination and polysomnography were performed during their hospitalization. Reactive oxygen metabolites (ROMs) were measured in blood samples by the diacron reactive oxygen metabolites (D-ROM) test. Twenty-one out of 26 subjects had an apnea/hypopnea index greater than 5 (OSA group). The measurement of free radicals was high in OSA patients. Furthermore, ROMs values in OSA patients were linearly correlated with the apnea/hypopnea index (R = 0.426; p = 0.042). The predictive value of a positive D-ROM test is 81%. ROMs were elevated in patients with OSA. When OSA was severe, similarly the value of ROMs in blood samples was enhanced, and the probable underlying mechanism for these events is the hypoxia/reoxygenation phenomenon.
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Tongue retaining devices for obstructive sleep apnea: A systematic review and meta-analysis.
Chang, Edward T; Fernandez-Salvador, Camilo; Giambo, Jeremy; Nesbitt, Blaine; Liu, Stanley Yung-Chuan; Capasso, Robson; Kushida, Clete A; Camacho, Macario
Tongue Retaining Devices (TRD) anteriorly displace the tongue with suction forces while patients sleep. TRD provide a non-surgical treatment option for patients with Obstructive Sleep Apnea (OSA). Our objective was to conduct a systematic review of the international literature for TRD outcomes as treatment for OSA. Three authors independently and systematically searched four databases (including PubMed/MEDLINE) through June 26, 2016. We followed guidelines set within the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Sixteen studies with 242 patients met criteria. The overall means±standard deviations (M±SD) for apnea-hypopnea index (AHI) decreased from 33.6±21.1/h to 15.8±16.0/h (53% reduction). Seven studies (81 patients) reported lowest oxygen saturation (LSAT), which improved from 79.8±17.5% to 83.9±8.6%. Four studies (93 patients) reported Epworth sleepiness scale (ESS), which decreased from 10.8±4.8 to 8.2±4.5, p <0.0001. Four studies (31 patients) reported Oxygen Desaturation Index (ODI) which decreased from 29.6±32.1 to 12.9±8.7, a 56.4% reduction. Current international literature demonstrates that tongue retaining devices reduce apnea-hypopnea index by 53%, increase lowest oxygen saturation by 4.1 oxygen saturation points, decrease oxygen desaturation index by 56% and decrease Epworth sleepiness scale scores by 2.8 points. Tongue retaining devices provide a statistically effective alternative treatment option for obstructive sleep apnea. Published by Elsevier Inc.
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Growth Outcomes of Preterm Infants Exposed to Different Oxygen Saturation Target Ranges from Birth
Navarrete, Cristina T.; Wrage, Lisa A.; Carlo, Waldemar A.; Walsh, Michele C.; Rich, Wade; Gantz, Marie G.; Das, Abhik; Schibler, Kurt; Newman, Nancy S.; Piazza, Anthony J.; Poindexter, Brenda B.; Shankaran, Seetha; Sánchez, Pablo J.; Morris, Brenda H.; Frantz, Ivan D.; Van Meurs, Krisa P.; Cotten, C. Michael; Ehrenkranz, Richard A.; Bell, Edward F.; Watterberg, Kristi L.; Higgins, Rosemary D.; Duara, Shahnaz
2017-01-01
Objective To test whether infants randomized to a lower oxygen saturation (SpO2) target range while on supplemental oxygen from birth will have better growth velocity from birth to 36 weeks postmenstrual age (PMA), and less growth failure at 36 weeks PMA and 18–22 months corrected age. Study design We evaluated a subgroup of 810 preterm infants from the Surfactant, Positive Pressure, and Oxygenation Randomized Trial, randomized at birth to lower (85–89%, n=402, GA 26 ± 1wk, BW 839 ± 186 g) or higher (91–95%, n=408, GA 26 ± 1wk, BW 840 ± 191 g) SpO2 target ranges. Anthropometric measures were obtained at birth, postnatal days 7, 14, 21, and 28; then at 32 and 36 weeks PMA, and 18–22 months corrected age. Growth velocities were estimated using the exponential method and analyzed using linear mixed models. Poor growth outcome, defined as weight < 10th percentile at 36 weeks PMA and 18–22 months corrected age, was compared across the two treatment groups using robust Poisson regression. Results Growth outcomes including growth at 36 weeks PMA and 18–22 months corrected age, as well as growth velocity were similar in the lower and higher SpO2 target groups. Conclusion Targeting different oxygen saturation ranges between 85% and 95% from birth did not impact growth velocity or reduce growth failure in preterm infants. PMID:27344218
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Characterization and impact of "dead-zone" eddies in the tropical Northeast Atlantic Ocean
NASA Astrophysics Data System (ADS)
Schuette, Florian; Karstensen, Johannes; Krahmann, Gerd; Hauss, Helena; Fiedler, Björn; Brandt, Peter; Visbeck, Martin; Körtzinger, Arne
2016-04-01
Localized open-ocean low-oxygen dead-zones in the tropical Northeast Atlantic are recently discovered ocean features that can develop in dynamically isolated water masses within cyclonic eddies (CE) and anticyclonic modewater eddies (ACME). Analysis of a comprehensive oxygen dataset obtained from gliders, moorings, research vessels and Argo floats shows that eddies with low oxygen concentrations at 50-150 m depths can be found in surprisingly high numbers and in a large area (from about 5°N to 20°N, from the shelf at the eastern boundary to 30°W). Minimum oxygen concentrations of about 9 μmol/kg in CEs and close to anoxic concentrations (< 1 μmol/kg) in ACMEs were observed. In total, 495 profiles with oxygen concentrations below the minimum background concentration of 40 μmol/kg could be associated with 27 independent "dead-zone" eddies (10 CEs; 17 ACMEs). The low oxygen concentration right beneath the mixed layer has been attributed to the combination of high productivity in the surface waters of the eddies and the isolation of the eddies' cores. Indeed eddies of both types feature a cold sea surface temperature anomaly and enhanced chlorophyll concentrations in their center. The oxygen minimum is located in the eddy core beneath the mixed layer at around 80 m depth. The mean oxygen anomaly between 50 to 150 m depth for CEs (ACMEs) is -49 (-81) μmol/kg. Eddies south of 12°N carry weak hydrographic anomalies in their cores and seem to be generated in the open ocean away from the boundary. North of 12°N, eddies of both types carry anomalously low salinity water of South Atlantic Central Water origin from the eastern boundary upwelling region into the open ocean. This points to an eddy generation near the eastern boundary. A conservative estimate yields that around 5 dead-zone eddies (4 CEs; 1 ACME) per year entering the area north of 12°N between the Cap Verde Islands and 19°W. The associated contribution to the oxygen budget of the shallow oxygen minimum zone in that area is about -10.3 (-3.0) μmol/kg/yr for CEs (ACMEs). The consumption within these eddies represents an essential part of the total consumption in the open tropical Northeast Atlantic Ocean and might be partly responsible for the formation of the shallow oxygen minimum zone.
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NASA Astrophysics Data System (ADS)
Schroeder, C. B.; Fawley, W. M.; Esarey, E.
2003-07-01
We investigate the statistical properties (e.g., shot-to-shot power fluctuations) of the radiation from a high-gain free-electron laser (FEL) operating in the nonlinear regime. We consider the case of an FEL amplifier reaching saturation whose shot-to-shot fluctuations in input radiation power follow a gamma distribution. We analyze the corresponding output power fluctuations at and beyond saturation, including beam energy spread effects, and find that there are well-characterized values of undulator length for which the fluctuations reach a minimum.
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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.
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Study of Al-Si Alloy Oxygen Saturation on Its Microstructure and Mechanical Properties.
Finkelstein, Arkady; Schaefer, Arseny; Chikova, Оlga; Borodianskiy, Konstantin
2017-07-11
One of the main goals of modern materials research is obtaining different microstructures and studying their influence on the mechanical properties of metals; aluminum alloys are particularly of interest due to their advanced performance. Traditionally, their required properties are obtained by alloying process, modification, or physical influence during solidification. The present work describes a saturation of the overheated AlSi₇Fe₁ casting alloy by oxides using oxygen blowing approach in overheated alloy. Changes in metals' microstructural and mechanical properties are also described in the work. An Al 10 SiFe intermetallic complex compound was obtained as a preferable component to Al₂O₃ precipitation on it, and its morphology was investigated by scanning electron microscopy. The mechanical properties of the alloy after the oxygen blowing treatment are discussed in this work.
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NASA Astrophysics Data System (ADS)
Deng, Zijian; Li, Changhui
2016-06-01
Imaging small blood vessels and measuring their functional information in finger joint are still challenges for clinical imaging modalities. In this study, we developed a multi-transducer functional photoacoustic tomography (PAT) system and successfully imaged human finger-joint vessels from ˜1 mm to <0.2 mm in diameter. In addition, the oxygen saturation (SO2) values of these vessels were also measured. Our results demonstrate that PAT can provide both anatomical and functional information of individual finger-joint vessels with different sizes, which might help the study of finger-joint diseases, such as rheumatoid arthritis.
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USDA-ARS?s Scientific Manuscript database
Genetic determinants of sleep-disordered breathing (SDB), a common set of disorders that contribute to significant cardiovascular and neuropsychiatric morbidity, are not clear. Overnight nocturnal oxygen saturation (SaO2) is a clinically relevant and easily measured indicator of SDB severity but its...
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Kim, Eun Jin; Jung, Chi Young; Kim, Kyung Chan
2018-06-19
Bronchoalveolar lavage (BAL) is a necessary procedure for diagnosis of various lung diseases. High-flow nasal cannula (HFNC) oxygen delivery was recently introduced. This study aimed to investigate the safety and effectiveness of HFNC oxygen supply during BAL procedure in patients with acute respiratory failure (ARF). Patients who underwent BAL while using HFNC at a partial pressure of oxygen in arterial blood/fraction of inspired oxygen (PaO₂/FiO₂; PF) ratio of 300 or below among patients who had been admitted from March 2013 to May 2017 were retrospectively investigated. Thirty-three BAL procedures were confirmed. Their baseline PF ratio was 166.1±46.7. FiO₂ values before, during, and after BAL were 0.45±0.12, 0.74±0.19, and 0.57±0.14, respectively. Flow (L/min) values before, during, and after BAL were 26.5±20.3, 49.0±7.2, and 40.8±14.2, respectively. Both FiO₂ and flow during and after the procedure were significantly different from those before the procedure (both p<0.001). Oxygen saturation levels before, during, and after BAL measured by pulse oximeter were 94.8±2.9, 94.6±3.5, and 95.2±2.8%, respectively. There were no significant differences in oxygen saturation among the three groups. Complications of BAL procedure included transient hypoxemia, hypotension, and fever. However, there was no endotracheal intubation within 24 hours. Baseline PF ratio in "without HFNC" group was significantly higher than that in "with HFNC" group. There were no differences in complications between the two groups. The use of HFNC during BAL procedure in ARF patients was effective and safe. However, there were no significant differences in oxygen saturation level and complications comparing "without HFNC" group in mild ARF. More studies are needed for moderate to severe ARF patients. Copyright©2018. The Korean Academy of Tuberculosis and Respiratory Diseases.
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Stress corrosion behavior of Ru-enhanced alpha-beta titanium alloys in methanol solutions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Schutz, R.W.; Horrigan, J.M.; Bednarowicz, T.A.
1998-12-31
Conservative, practical guidelines for the minimum water content required to prevent methanolic stress corrosion cracking (SCC) of Ti-6Al-4V-Ru and Ti-3Al-2.5V-Ru alloy tubulars have been developed from slow strain rate testing in plain and acidified NaCl-saturated methanol-water solutions at 25 C. A minimum methanol water content of 10 wt.% is proposed for Ti-6Al-4V-Ru, whereas 2-3 wt.% is sufficient for the lower strength Ti-3Al-2.5V-Ru alloy. Although HCl-acidification aggravated methanolic SCC, intermixing of methanol with crude oil or pure hydrocarbons, H{sub 2}S gas saturation, and/or increasing temperature diminished cracking susceptibility in these alloy tubulars.
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OXYGENATION OF HYDROCARBONS USING NANOSTRUCTURED TIO2 AS A PHOTOCATALYST: A GREEN ALTERNATIVE
High-value organic compounds have been synthesized successfully from linear and cyclic saturated hydrocarbons by a photocatalytic oxidation process using a semiconductor material, titanium dioxide (TiO2). Various hydrocarbons were partially oxygenated in both aqueous and gaseous...
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2012-02-01
a slight increase in oxygen consumption during exercise, without a decrement in capillary hemoglobin oxygen saturation compared to exercise on 85...must be provided. HSI education and training for program managers and acquisition professionals are required. Meaningful, quantifiable...positions were transferred to the 711th HPW at WPAFB. Only two of the analysts moved to WPAFB, creating a major shortfall in HSI education , training, and
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The relationship between oxygen affinity and 2,3 diphosphoglycerate (2,3 DPG) in the red cell has been studied in chronic hypercapnia induced by...initial values after seven days of exposure. Both oxygen half-saturation pressure (P50) and the level of 2,3 DPG of the red cells followed the time
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Noninvasive imaging of human skin hemodynamics using a digital red-green-blue camera
NASA Astrophysics Data System (ADS)
Nishidate, Izumi; Tanaka, Noriyuki; Kawase, Tatsuya; Maeda, Takaaki; Yuasa, Tomonori; Aizu, Yoshihisa; Yuasa, Tetsuya; Niizeki, Kyuichi
2011-08-01
In order to visualize human skin hemodynamics, we investigated a method that is specifically developed for the visualization of concentrations of oxygenated blood, deoxygenated blood, and melanin in skin tissue from digital RGB color images. Images of total blood concentration and oxygen saturation can also be reconstructed from the results of oxygenated and deoxygenated blood. Experiments using tissue-like agar gel phantoms demonstrated the ability of the developed method to quantitatively visualize the transition from an oxygenated blood to a deoxygenated blood in dermis. In vivo imaging of the chromophore concentrations and tissue oxygen saturation in the skin of the human hand are performed for 14 subjects during upper limb occlusion at 50 and 250 mm Hg. The response of the total blood concentration in the skin acquired by this method and forearm volume changes obtained from the conventional strain-gauge plethysmograph were comparable during the upper arm occlusion at pressures of both 50 and 250 mm Hg. The results presented in the present paper indicate the possibility of visualizing the hemodynamics of subsurface skin tissue.
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Cell respiration under hypoxia: facts and artefacts in mitochondrial oxygen kinetics.
Scandurra, Francesca M; Gnaiger, Erich
2010-01-01
When oxygen supply to tissues is limiting, mitochondrial respiration and ATP production are compromised. To assess the bioenergetic consequences under normoxia and hypoxia, quantitative evaluation of mitochondrial oxygen kinetics is required. Using high-resolution respirometry, the "apparent K (m)" for oxygen or p (50) of respiration in 32D cells was determined at 0.05 +/- 0.01 kPa (0.4 mmHg, 0.5 microM, 0.25% air saturation). Close agreement with p (50) of isolated mitochondria indicates that intracellular gradients are small in small cells at routine activity. At intracellular p (O2) <2 kPa (15 mmHg, 10% air saturation) in various tissues under normoxia, respiration is limited by >2% with a p (50) of 0.05 kPa. Over-estimation of p (50) at 0.4 kPa (3 mmHg) would imply significant (>17%) oxygen limitation of respiration under intracellular normoxia. Based on a critical review, we conclude that p (50) ranges from 0.01 to 0.10 kPa in mitochondria and small cells in the absence of inhibitors of cytochrome c oxidase, whereas experimental artefacts explain the controversial >200-fold range of p (50) in the literature on mitochondrial oxygen kinetics.
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NASA Astrophysics Data System (ADS)
Jiang, Yan; Zemp, Roger
2018-01-01
The metabolic rate of oxygen consumption is an important metric of tissue oxygen metabolism and is especially critical in the brain, yet few methods are available for measuring it. We use a custom combined photoacoustic-microultrasound system and demonstrate cerebral oxygen consumption estimation in vivo. In particular, the cerebral metabolic rate of oxygen consumption was estimated in a murine model during variation of inhaled oxygen from hypoxia to hyperoxia. The hypothesis of brain autoregulation was confirmed with our method even though oxygen saturation and flow in vessels changed.
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Sandra J. Bucci; Guillermo Goldstein; Frederick C. Meinzer; Augusto C. Franco; Paula Campanello; Fabián G. Scholz
2005-01-01
Seasonal regulation of leaf water potential (ΨL) was studied in eight dominant woody savanna species growing in Brazilian savanna (Cerrado) sites that experience a 5-month dry season. Despite marked seasonal variation in precipitation and air saturation deficit (D), seasonal differences in midday minimum Ψ...
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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.
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Reengineered glucose oxidase for amperometric glucose determination in diabetes analytics.
Arango Gutierrez, Erik; Mundhada, Hemanshu; Meier, Thomas; Duefel, Hartmut; Bocola, Marco; Schwaneberg, Ulrich
2013-12-15
Glucose oxidase is an oxidoreductase exhibiting a high β-D-glucose specificity and high stability which renders glucose oxidase well-suited for applications in diabetes care. Nevertheless, GOx activity is highly oxygen dependent which can lead to inaccuracies in amperometric β-D-glucose determinations. Therefore a directed evolution campaign with two rounds of random mutagenesis (SeSaM followed by epPCR), site saturation mutagenesis studies on individual positions, and one simultaneous site saturation library (OmniChange; 4 positions) was performed. A diabetes care well suited mediator (quinone diimine) was selected and the GOx variant (T30V I94V) served as starting point. For directed GOx evolution a microtiter plate detection system based on the quinone diimine mediator was developed and the well-known ABTS-assay was applied in microtiter plate format to validate oxygen independency of improved GOx variants. Two iterative rounds of random diversity generation and screening yielded to two subsets of amino acid positions which mainly improved activity (A173, A332) and oxygen independency (F414, V560). Simultaneous site saturation of all four positions with a reduced subset of amino acids using the OmniChange method yielded finally variant V7 with a 37-fold decreased oxygen dependency (mediator activity: 7.4 U/mg WT, 47.5 U/mg V7; oxygen activity: 172.3 U/mg WT, 30.1 U/mg V7). V7 is still highly β-D-glucose specific, highly active with the quinone diimine mediator and thermal resistance is retained (prerequisite for GOx coating of diabetes test stripes). The latter properties and V7's oxygen insensitivity make V7 a very promising candidate to replace standard GOx in diabetes care applications. Copyright © 2013 Elsevier B.V. All rights reserved.
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Bertolizio, Gianluca; DiNardo, James A; Laussen, Peter C; Polito, Angelo; Pigula, Frank A; Zurakowski, David; Kussman, Barry D
2015-02-01
Superior vena cava pressure after the bidirectional Glenn operation usually is higher than that associated with the preceding shunt-dependent circulation. The aim of the present study was to determine whether the acute elevation in central venous pressure was associated with changes in cerebral oxygenation and perfusion. Single-center prospective, observational cohort study. Academic children's hospital. Infants with single-ventricle lesions and surgically placed systemic-to-pulmonary artery shunts undergoing the bidirectional Glenn operation. Near-infrared spectroscopy and transcranial Doppler sonography were used to measure regional cerebral oxygen saturation and cerebral blood flow velocity. Mean differences in regional cerebral oxygen saturation and cerebral blood flow velocity before anesthetic induction and shortly before hospital discharge were compared using the F-test in repeated measures analysis of variance. In the 24 infants studied, mean cerebral oxygen saturation increased from 49%±2% to 57%±2% (p = 0.007), mean cerebral blood flow velocity decreased from 57±4 cm/s to 47±4 cm/s (p = 0.026), and peak systolic cerebral blood flow velocity decreased from 111±6 cm/s to 99±6 cm/s (p = 0.046) after the bidirectional Glenn operation. Mean central venous pressure was 8±2 mmHg postinduction of anesthesia and 14±4 mmHg on the first postoperative day and was not associated with a change in cerebral perfusion pressure (p = 0.35). The bidirectional Glenn operation in infants with a shunt-dependent circulation is associated with an improvement in cerebral oxygenation, and the lower cerebral blood flow velocity is likely a response of intact cerebral autoregulation. Copyright © 2014 Elsevier Inc. All rights reserved.
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A confocal scanning laser ophthalmoscope for retinal vessel oximetry
NASA Astrophysics Data System (ADS)
Lompado, Arthur
Measurement of a person's blood oxygen saturation has long been recognized as a useful metric for the characterizing ailments ranging from chronic respiratory disorders to acute, potentially life threatening, traumas. The ubiquity of oxygen saturation monitors in the medical field, including portable pulse oximeters and laboratory based CO-oximeters, is a testament to the importance of this technique. The work presented here documents the design, fabrication and development of a unique type of oxygen saturation monitor, a confocal scanning retinal vessel oximeter, with the potential to expand the usefulness of the present devices. A large part of the knowledge base required to construct the instrument comes from the consideration of light scattering by red blood cells in a blood vessel. Therefore, a substantial portion of this work is devoted to the process of light scattering by whole human blood and its effects on the development of a more accurate oximeter. This light scattering effect has been both measured and modeled stochastically to determine its contribution to the measured oximeter signal. It is shown that, although well accepted in the published literature, the model only correlates marginally to the measurements due to inherent limitations imposed by the model assumptions. Nonetheless, enough material has been learned about the scattering to allow development of a mathematical model for the interaction of light with blood in a vessel, and this knowledge has been applied to the data reduction of the present oximeter. This data reduction technique has been tested in a controlled experiment employing a model eye with a blood filled mock retinal vessel. It will be shown that the presently developed technique exhibited strong correlation between the known blood oxygen saturation and that calculated by the new system.
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Yadlapati, Ajay; Grogan, Tristan; Elashoff, David; Kelly, Robert B.
2013-01-01
Abstract: Using a novel noninvasive, visible-light optical diffusion oximeter (T-Stat VLS Tissue Oximeter; Spectros Corporation, Portola Valley, CA) to measure the tissue oxygen saturation (StO2) of the buccal mucosa, the correlation between StO2 and central venous oxygen saturation (ScvO2) was examined in children with congenital cyanotic heart disease undergoing a cardiac surgical procedure. Paired StO2 and serum ScvO2 measurements were obtained postoperatively and statistically analyzed for agreement and association. Thirteen children (nine male) participated in the study (age range, 4 days to 18 months). Surgeries included Glenn shunt procedures, Norwood procedures, unifocalization procedures with Blalock-Taussig shunt placement, a Kawashima/Glenn shunt procedure, a Blalock-Taussig shunt placement, and a modified Norwood procedure. A total of 45 paired StO2-ScvO2 measurements was obtained. Linear regression demonstrated a Pearson’s correlation of .58 (95% confidence interval [CI], .35–.75; p < .0001). The regression slope coefficient estimate was .95 (95% CI, .54–1.36) with an interclass correlation coefficient of .48 (95% CI, .22–.68). Below a clinically relevant average ScvO2 value, a receiver operator characteristic analysis yielded an area under the curve of .78. Statistical methods to control for repeatedly measuring the same subjects produced similar results. This study shows a moderate relationship and agreement between StO2 and ScvO2 measurements in pediatric patients with a history of congenital cyanotic heart disease undergoing a cardiac surgical procedure. This real-time monitoring device can act as a valuable adjunct to standard noninvasive monitoring in which serum ScvO2 sampling currently assists in the diagnosis of low cardiac output after pediatric cardiac surgery. PMID:23691783
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NASA Astrophysics Data System (ADS)
Bashtanov, M. E.; Drozdova, N. N.; Krasnovskii, A. A.
1999-12-01
An investigation was made of the ratios of the intensity Idf of the singlet-oxygen(1O2)-sensitised delayed fluorescence of the zinc complex of tetra(4-tert-butyl)phthalocyanine (ZnTBPc), with the maximum at λ = 685 nm, to the intensity I1270 of the photosensitised phosphorescence of 1O2 with the maximum at λ = 1270 nm in deuterated benzene when excited with λ = 337 nm nitrogen-laser pulses. Depending on the energy density of the laser radiation (0.25 — 0.7 mJ cm-2) and on the concentration of ZnTBPc (0.06 — 3.4 μM), the ratio of the zero-time intensities of the delayed fluorescence of ZnTBPc and of the singlet-oxygen phosphorescence Idf0/I12700 varied from 0.01 to 0.2 in air-saturated solutions of ZnTBPc. The intensity Idf0 decreased fivefold as a result of saturation with oxygen of air-saturated solutions. The quantum efficiency of the delayed fluorescence was represented by the coefficient α =(Idf0/I12700)kr/(γf[1O2]0[ZnTBPc]), where [1O2]0 is the zero-time concentration of 1O2 after a laser shot; kr is the rate constant of radiative deactivation of 1O2 in the investigated solvent; γf is the quantum yield of the ZnTBPc fluorescence. It was established that in the case of air-saturated solutions of ZnTBPc this coefficient was approximately 200 times less than for metal-free tetra(4-tert-butyl)phthalocyanine and its absolute value was ~2 × 1011 M-2 s-1.
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WE-E-BRE-12: Tumor Microenvironment Dynamics Following Radiation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Campos, D; Niles, D; Adamson, E
2014-06-15
Purpose: This work aims to understand the radiation-induced interplay between tumor oxygenation and metabolic activity. These dynamics can potentially serve as biomarkers in assessing treatment response allowing for patient-specific adaptive radiotherapy. Methods: Using patient-derived xenografts of head and neck cancer we assessed tumor oxygenation via fiber-optic probe monitored hemoglobin saturation and Blood Oxygen Level Dependent (BOLD) MRI. Measurements were taken before and after a 10 Gy dose of radiation. Changes in metabolic activity were measured via Fluorescence Lifetime IMaging (FLIM) with the appropriate controls following a 10 Gy dose of radiation. FLIM can non-invasively monitor changes in fluorescence in responsemore » to the microenvironment including being able to detect free and bound states of the intrinsically fluorescent metabolite NADH (Nicotinamide Adenine Dinucleotide). With this information FLIM can accurately quantify the metabolic state of cells that have been radiated. To model the observed changes, a two-compartment, source-sink simulation relating hemoglobin saturation and metabolic activity was performed using MATLAB. Results: Hemoglobin saturation as measured by interstitial probe and BOLD-MRI decreased by 30% within 15 minutes following radiation. FLIM demonstrated a decrease in the mean fluorescence lifetime of NADH by 100 ps following 10 Gy indicating a shift towards glycolytic pathways. Simulation of radiation-induced alterations in tumor oxygenation demonstrated that these changes can be the result of changes in either vasculature or metabolic activity. Conclusion: Radiation induces significant changes in hemoglobin saturation and metabolic activity. These alterations occur on time scales approximately the duration of common radiation treatments. Further understanding these dynamics has important implications with regard to improvement of therapy and biomarkers of treatment response.« less
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Variations in Vital Signs in the Last Days of Life in Patients With Advanced Cancer
Bruera, Sebastian; Chisholm, Gary; Dos Santos, Renata; Crovador, Camila; Bruera, Eduardo; Hui, David
2014-01-01
Context Few studies have examined variation in vital signs in the last days of life. Objectives We determined the variation of vital signs in the final two weeks of life in patients with advanced cancer and examined their association with impending death in three days. Methods In this prospective, longitudinal, observational study, we enrolled consecutive patients admitted to two acute palliative care units and documented their vital signs (heart rate, blood pressure, respiratory rate, oxygen saturation, and temperature) twice a day serially from admission to death or discharge. Results Of 357 patients, 203 (55%) died in hospital. Systolic blood pressure (P < 0.001), diastolic blood pressure (P < 0.001), and oxygen saturation (P < 0.001) decreased significantly in the final three days of life, and temperature increased slightly (P < 0.04). Heart rate (P = 0.22) and respiratory rate (P = 0.24) remained similar in the last three days. Impending death in three days was significantly associated with increased heart rate (odds ratio [OR] = 2; P = 0.01), decreased systolic blood pressure (OR = 2.5; P = 0.004), decreased diastolic blood pressure (OR = 2.3; P = 0.002), and decreased oxygen saturation (OR = 3.7; P = 0.003) from baseline readings on admission. These changes had high specificity (≥80%), low sensitivity (≤35%), and modest positive likelihood ratios (≤5) for impending death within three days. A large proportion of patients had normal vital signs in the last days of life. Conclusion Blood pressure and oxygen saturation decreased in the last days of life. Clinicians and families cannot rely on vital sign changes alone to rule in or rule out impending death. Our findings do not support routine vital signs monitoring of patients who are imminently dying. PMID:24731412
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NASA Astrophysics Data System (ADS)
Panyi, A.; Long, M. H.; Mooney, T. A.
2016-02-01
While young animals found future cohorts and populations, these early life stages are often particularly susceptible to conditions of the local environment in which they develop. The oxygen and pH of this critical developmental environment is likely impacted by the nearby physical conditions and the animals own respirations. Yet, in nearly all cases, this microenvironment is unknown, limiting our understanding of animal tolerances to current and future OA and hypoxic conditions. This study investigated the oxygen and pH environment adjacent to and within the egg cases of a keystone species, the longfin squid, Doryteuthis pealeii, under ambient and elevated CO2 (400 and 2200 ppm), and across differing water flow rates (0, 1, and 10 cm/s) using microprobes. Under both CO2 treatments, oxygen and pH in the egg case centers dropped dramatically across development to levels generally considered metabolically stressful even for adults. In the ambient CO2 trial, oxygen concentrations reached a minimum of 4.351 µmol/L, and pH reached a minimum of 7.36. In the elevated CO2 trial, oxygen concentrations reached a minimum of 9.910 µmol/L, and pH reached a minimum of 6.79. Flow appeared to alleviate these conditions, with highest O2 concentrations in the egg cases exposed to 10 cm/s flow in both CO2 trials, across all age classes measured. Surprisingly, all tested egg cases successfully hatched, demonstrating that developing D. pealeii embryos have a strong tolerance for low oxygen and pH, but there were more unsuccessful embryos counted in the 0 and 1 cm/s flow conditions. Further climate change could place young, keystone squid outside of their physiological limits, but water flow may play a key role in mitigating developmental stress to egg case bound embryos by increasing available oxygen.
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Mainali, Laxman; Vasquez-Vivar, Jeannette; Hyde, James S.; Subczynski, Witold K.
2015-01-01
This study validated the use of small unilamellar vesicles (SUVs) made of 1-palmitoyl-2-oleoylphosphatidylcholine with 1 mol% spin label of 1-palmitoyl-2-(16-doxylstearoyl)phosphatidylcholine (16-PC) as an oxygen sensitive analyte to study cellular respiration. In the analyte the hydrocarbon environment surrounds the nitroxide moiety of 16-PC. This ensures high oxygen concentration and oxygen diffusion at the location of the nitroxide as well as isolation of the nitroxide moiety from cellular reductants and paramagnetic ions that might interfere with spin-label oximetry measurements. The saturation-recovery EPR approach was applied in the analysis since this approach is the most direct method to carry out oximetric studies. It was shown that this display (spin-lattice relaxation rate) is linear in oxygen partial pressure up to 100% air (159 mmHg). Experiments using a neuronal cell line in suspension were carried out at X-band for closed chamber geometry. Oxygen consumption rates showed a linear dependence on the number of cells. Other significant benefits of the analyte are: the fast effective rotational diffusion and slow translational diffusion of the spin-probe is favorable for the measurements, and there is no cross reactivity between oxygen and paramagnetic ions in the lipid bilayer. PMID:26441482
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Mainali, Laxman; Vasquez-Vivar, Jeannette; Hyde, James S; Subczynski, Witold K
2015-08-01
This study validated the use of small unilamellar vesicles (SUVs) made of 1-palmitoyl-2-oleoylphosphatidylcholine with 1 mol% spin label of 1-palmitoyl-2-(16-doxylstearoyl)phosphatidylcholine (16-PC) as an oxygen sensitive analyte to study cellular respiration. In the analyte the hydrocarbon environment surrounds the nitroxide moiety of 16-PC. This ensures high oxygen concentration and oxygen diffusion at the location of the nitroxide as well as isolation of the nitroxide moiety from cellular reductants and paramagnetic ions that might interfere with spin-label oximetry measurements. The saturation-recovery EPR approach was applied in the analysis since this approach is the most direct method to carry out oximetric studies. It was shown that this display (spin-lattice relaxation rate) is linear in oxygen partial pressure up to 100% air (159 mmHg). Experiments using a neuronal cell line in suspension were carried out at X-band for closed chamber geometry. Oxygen consumption rates showed a linear dependence on the number of cells. Other significant benefits of the analyte are: the fast effective rotational diffusion and slow translational diffusion of the spin-probe is favorable for the measurements, and there is no cross reactivity between oxygen and paramagnetic ions in the lipid bilayer.
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Landkamer, Lee L.; Harvey, Ronald W.; Scheibe, Timothy D.; Ryan, Joseph N.
2013-01-01
A colloid transport model is introduced that is conceptually simple yet captures the essential features of colloid transport and retention in saturated porous media when colloid retention is dominated by the secondary minimum because an electrostatic barrier inhibits substantial deposition in the primary minimum. This model is based on conventional colloid filtration theory (CFT) but eliminates the empirical concept of attachment efficiency. The colloid deposition rate is computed directly from CFT by assuming all predicted interceptions of colloids by collectors result in at least temporary deposition in the secondary minimum. Also, a new paradigm for colloid re-entrainment based on colloid population heterogeneity is introduced. To accomplish this, the initial colloid population is divided into two fractions. One fraction, by virtue of physiochemical characteristics (e.g., size and charge), will always be re-entrained after capture in a secondary minimum. The remaining fraction of colloids, again as a result of physiochemical characteristics, will be retained “irreversibly” when captured by a secondary minimum. Assuming the dispersion coefficient can be estimated from tracer behavior, this model has only two fitting parameters: (1) the fraction of the initial colloid population that will be retained “irreversibly” upon interception by a secondary minimum, and (2) the rate at which reversibly retained colloids leave the secondary minimum. These two parameters were correlated to the depth of the Derjaguin-Landau-Verwey-Overbeek (DLVO) secondary energy minimum and pore-water velocity, two physical forces that influence colloid transport. Given this correlation, the model serves as a heuristic tool for exploring the influence of physical parameters such as surface potential and fluid velocity on colloid transport.
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Blood oxygen binding in hypoxaemic calves.
Cambier, Carole; Clerbaux, Thierry; Detry, Bruno; Marville, Vincent; Frans, Albert; Gustin, Pascal
2002-01-01
Blood oxygen transport and tissue oxygenation were studied in 28 calves from the Belgian White and Blue breed (20 healthy and 8 hypoxaemic ones). Hypoxaemic calves were selected according to their high respiratory frequency and to their low partial oxygen pressure (PaO2) in the arterial blood. Venous and arterial blood samples were collected, and 2,3-diphosphoglycerate, adenosine triphosphate, chloride, inorganic phosphate and hemoglobin concentrations, and pH, PCO, and PO2 were determined. An oxygen equilibrium curve (OEC) was measured in standard conditions, for each animal. The arterial and venous OEC were calculated, taking body temperature, pH and PCO2 values in arterial and venous blood into account. The oxygen exchange fraction (OEF%), corresponding to the degree of blood desaturation between the arterial and the venous compartments, and the amount of oxygen released at the tissue level by 100 mL of blood (OEF Vol%) were calculated from the arterial and venous OEC combined with the PO2 and hemoglobin concentration. In hypoxaemic calves investigated in this study, the hemoglobin oxygen affinity, measured under standard conditions, was not modified. On the contrary, in vivo acidosis and hypercapnia induced a decrease in the hemoglobin oxygen affinity in arterial blood, which combined to the decrease in PaO2 led to a reduced hemoglobin saturation degree in the arterial compartment. However, this did not impair the oxygen exchange fraction (OEF%), since the hemoglobin saturation degree in venous blood was also diminished.
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Effects of caffeine on the preterm brain: An observational study.
Dix, Laura M L; van Bel, Frank; Baerts, Willem; Lemmers, Petra M A
2018-05-01
Caffeine improves neurodevelopmental outcome of preterm infants. This study analyses the effects of caffeine on the neonatal brain. We hypothesized that caffeine has a neuroprotective effect through an increase in oxygen metabolism; reflected by increased cerebral oxygen extraction, electrical function, and perfusion. Preterm infants <32 weeks gestation (GA) receiving their primary dose caffeine-base (10 mg/kg) were included. Ten minutes of stable monitoring were selected before, during, and every hour up to 6 h after caffeine. Near-infrared spectroscopy monitored regional cerebral oxygenation (rScO 2 ) and extraction (FTOE). Amplitude-integrated electroencephalogram (aEEG) monitored minimum, mean and maximum amplitudes. Spontaneous activity transients (SAT) rate and the interval between SATs (ISI) were calculated. Mean arterial blood pressure (MABP), heart rate (HR) and arterial oxygen saturation (SaO 2 ) were monitored. Arterial pCO 2 's were collected before and 4 h after caffeine. Brain perfusion was assessed 1 h before and 3 h after caffeine by Doppler-measured resistance-index (RI), peak systolic velocity (PSV) and end-diastolic velocity (EDV), in the anterior cerebral artery (ACA) and internal carotid artery (ICA). Results were presented in mean ± SD. 34 infants, mean GA 28.8 ± 2.1 wk, were included. rScO 2 significantly decreased from 69 ± 11 to 63 ± 12 1 h after caffeine, and recovered at 6 h (66 ± 10). FTOE increased correspondingly. MABP and HR increased significantly. PSV in the ACA decreased slightly. Other Doppler variables, aEEG parameters, and SaO 2 were unaffected. Caffeine increases oxygen extraction, suggesting a (transient) stimulating effect on brain metabolism. However, no substantial changes were found in brain perfusion and in electrical brain activity. Copyright © 2018 Elsevier B.V. All rights reserved.
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Near-infrared spectroscopy of renal tissue in vivo
NASA Astrophysics Data System (ADS)
Grosenick, Dirk; Steinkellner, Oliver; Wabnitz, Heidrun; Macdonald, Rainer; Niendorf, Thoralf; Cantow, Kathleen; Flemming, Bert; Seeliger, Erdmann
2013-03-01
We have developed a method to quantify hemoglobin concentration and oxygen saturation within the renal cortex by near-infrared spectroscopy. A fiber optic probe was used to transmit the radiation of three semiconductor lasers at 690 nm, 800 nm and 830 nm to the tissue, and to collect diffusely remitted light at source-detector separations from 1 mm to 4 mm. To derive tissue hemoglobin concentration and oxygen saturation of hemoglobin the spatial dependence of the measured cw intensities was fitted by a Monte Carlo model. In this model the tissue was assumed to be homogeneous. The scaling factors between measured intensities and simulated photon flux were obtained by applying the same setup to a homogeneous semi-infinite phantom with known optical properties and by performing Monte Carlo simulations for this phantom. To accelerate the fit of the tissue optical properties a look-up table of the simulated reflected intensities was generated for the needed range of absorption and scattering coefficients. The intensities at the three wavelengths were fitted simultaneously using hemoglobin concentration, oxygen saturation, the reduced scattering coefficient at 800 nm and the scatter power coefficient as fit parameters. The method was employed to study the temporal changes of renal hemoglobin concentration and blood oxygenation on an anesthetized rat during a short period of renal ischemia induced by aortic occlusion and during subsequent reperfusion.
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Minimizing excess air could be wasting energy in process heaters
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lieberman, N.P.
1988-02-01
Operating a process heater simply to achieve a minimum excess oxygen target in the flue gas may be wasting energy in some process heaters. That's because the real minimum excess oxygen percentage is that required to reach the point of absolute combustion in the furnace. The oxygen target required to achieve absolute combustion may be 1%, or it may be 6%, depending on the operating characteristics of the furnace. Where natural gas is burned, incomplete combustion can occur, wasting fuel dollars. Energy can be wasted because of some misconceptions regarding excess air control. These are: 2-3% excess oxygen in themore » flue gas is a universally good target, too little excess oxygen will always cause the evolution of black smoke in the stack, and excess air requirements are unaffected by commissioning an air preheater.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Eisenhardt, A.; Reiß, S.; Krischok, S., E-mail: stefan.krischok@tu-ilmenau.de
2014-01-28
The influence of selected donor- and acceptor-type adsorbates on the electronic properties of InN(0001) surfaces is investigated implementing in-situ photoelectron spectroscopy. The changes in work function, surface band alignment, and chemical bond configurations are characterized during deposition of potassium and exposure to oxygen. Although an expected opponent charge transfer characteristic is observed with potassium donating its free electron to InN, while dissociated oxygen species extract partial charge from the substrate, a reduction of the surface electron accumulation occurs in both cases. This observation can be explained by adsorbate-induced saturation of free dangling bonds at the InN resulting in the disappearancemore » of surface states, which initially pin the Fermi level and induce downward band bending.« less
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Partial oxidation of methane by pulsed corona discharges
NASA Astrophysics Data System (ADS)
Hoeben, W. F. L. M.; Boekhoven, W.; Beckers, F. J. C. M.; van Heesch, E. J. M.; Pemen, A. J. M.
2014-09-01
Pulsed corona-induced partial oxidation of methane in humid oxygen or carbon dioxide atmospheres has been investigated for future fuel synthesis applications. The obtained product spectrum is wide, i.e. saturated, unsaturated and oxygen-functional hydrocarbons. The generally observed methane conversion levels are 6-20% at a conversion efficiency of about 100-250 nmol J-1. The main products are ethane, ethylene and acetylene. Higher saturated hydrocarbons up to C6 have been detected. The observed oxygen-functional hydrocarbons are methanol, ethanol and lower concentrations of aldehydes, ketones, dimethylether and methylformate. Methanol seems to be exclusively produced with CH4/O2 mixtures at a maximum production efficiency of 0.35 nmol J-1. CH4/CO2 mixtures appear to yield higher hydrocarbons. Carboxylic acids appear to be mainly present in the aqueous reactor phase, possibly together with higher molecular weight species.
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Safety of Induced Sputum Collection in Children Hospitalized With Severe or Very Severe Pneumonia
DeLuca, Andrea N.; Hammitt, Laura L.; Kim, Julia; Higdon, Melissa M.; Baggett, Henry C.; Brooks, W. Abdullah; Howie, Stephen R. C.; Deloria Knoll, Maria; Kotloff, Karen L.; Levine, Orin S.; Madhi, Shabir A.; Murdoch, David R.; Scott, J. Anthony G.; Thea, Donald M.; Amornintapichet, Tussanee; Awori, Juliet O.; Chuananon, Somchai; Driscoll, Amanda J.; Ebruke, Bernard E.; Hossain, Lokman; Jahan, Yasmin; Kagucia, E. Wangeci; Kazungu, Sidi; Moore, David P.; Mudau, Azwifarwi; Mwananyanda, Lawrence; Park, Daniel E.; Prosperi, Christine; Seidenberg, Phil; Sylla, Mamadou; Tapia, Milagritos D.; Zaman, Syed M. A.; O’Brien, Katherine L.; Levine, Orin S.; Knoll, Maria Deloria; Feikin, Daniel R.; DeLuca, Andrea N.; Driscoll, Amanda J.; Fancourt, Nicholas; Fu, Wei; Hammitt, Laura L.; Higdon, Melissa M.; Kagucia, E. Wangeci; Karron, Ruth A.; Li, Mengying; Park, Daniel E.; Prosperi, Christine; Wu, Zhenke; Zeger, Scott L.; Watson, Nora L.; Crawley, Jane; Murdoch, David R.; Brooks, W. Abdullah; Endtz, Hubert P.; Zaman, Khalequ; Goswami, Doli; Hossain, Lokman; Jahan, Yasmin; Ashraf, Hasan; Howie, Stephen R. C.; Ebruke, Bernard E.; Antonio, Martin; McLellan, Jessica; Machuka, Eunice; Shamsul, Arifin; Zaman, Syed M.A.; Mackenzie, Grant; Scott, J. Anthony G.; Awori, Juliet O.; Morpeth, Susan C.; Kamau, Alice; Kazungu, Sidi; Silaba, Micah; Kotloff, Karen L.; Tapia, Milagritos D.; Sow, Samba O.; Sylla, Mamadou; Tamboura, Boubou; Onwuchekwa, Uma; Kourouma, Nana; Toure, Aliou; Madhi, Shabir A.; Moore, David P.; Adrian, Peter V.; Baillie, Vicky L.; Kuwanda, Locadiah; Mudau, Azwifarwi; Groome, Michelle J.; Mahomed, Nasreen; Baggett, Henry C.; Thamthitiwat, Somsak; Maloney, Susan A.; Bunthi, Charatdao; Rhodes, Julia; Sawatwong, Pongpun; Akarasewi, Pasakorn; Thea, Donald M.; Mwananyanda, Lawrence; Chipeta, James; Seidenberg, Phil; Mwansa, James; wa Somwe, Somwe; Kwenda, Geoffrey
2017-01-01
Abstract Background. Induced sputum (IS) may provide diagnostic information about the etiology of pneumonia. The safety of this procedure across a heterogeneous population with severe pneumonia in low- and middle-income countries has not been described. Methods. IS specimens were obtained as part a 7-country study of the etiology of severe and very severe pneumonia in hospitalized children <5 years of age. Rigorous clinical monitoring was done before, during, and after the procedure to record oxygen requirement, oxygen saturation, respiratory rate, consciousness level, and other evidence of clinical deterioration. Criteria for IS contraindications were predefined and serious adverse events (SAEs) were reported to ethics committees and a central safety monitor. Results. A total of 4653 IS procedures were done among 3802 children. Thirteen SAEs were reported in relation to collection of IS, or 0.34% of children with at least 1 IS specimen collected (95% confidence interval, 0.15%–0.53%). A drop in oxygen saturation that required supplemental oxygen was the most common SAE. One child died after feeding was reinitiated 2 hours after undergoing sputum induction; this death was categorized as “possibly related” to the procedure. Conclusions. The overall frequency of SAEs was very low, and the nature of most SAEs was manageable, demonstrating a low-risk safety profile for IS collection even among severely ill children in low-income-country settings. Healthcare providers should monitor oxygen saturation and requirements during and after IS collection, and assess patients prior to reinitiating feeding after the IS procedure, to ensure patient safety. PMID:28575356
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Safety of Induced Sputum Collection in Children Hospitalized With Severe or Very Severe Pneumonia.
DeLuca, Andrea N; Hammitt, Laura L; Kim, Julia; Higdon, Melissa M; Baggett, Henry C; Brooks, W Abdullah; Howie, Stephen R C; Deloria Knoll, Maria; Kotloff, Karen L; Levine, Orin S; Madhi, Shabir A; Murdoch, David R; Scott, J Anthony G; Thea, Donald M; Amornintapichet, Tussanee; Awori, Juliet O; Chuananon, Somchai; Driscoll, Amanda J; Ebruke, Bernard E; Hossain, Lokman; Jahan, Yasmin; Kagucia, E Wangeci; Kazungu, Sidi; Moore, David P; Mudau, Azwifarwi; Mwananyanda, Lawrence; Park, Daniel E; Prosperi, Christine; Seidenberg, Phil; Sylla, Mamadou; Tapia, Milagritos D; Zaman, Syed M A; O'Brien, Katherine L
2017-06-15
Induced sputum (IS) may provide diagnostic information about the etiology of pneumonia. The safety of this procedure across a heterogeneous population with severe pneumonia in low- and middle-income countries has not been described. IS specimens were obtained as part a 7-country study of the etiology of severe and very severe pneumonia in hospitalized children <5 years of age. Rigorous clinical monitoring was done before, during, and after the procedure to record oxygen requirement, oxygen saturation, respiratory rate, consciousness level, and other evidence of clinical deterioration. Criteria for IS contraindications were predefined and serious adverse events (SAEs) were reported to ethics committees and a central safety monitor. A total of 4653 IS procedures were done among 3802 children. Thirteen SAEs were reported in relation to collection of IS, or 0.34% of children with at least 1 IS specimen collected (95% confidence interval, 0.15%-0.53%). A drop in oxygen saturation that required supplemental oxygen was the most common SAE. One child died after feeding was reinitiated 2 hours after undergoing sputum induction; this death was categorized as "possibly related" to the procedure. The overall frequency of SAEs was very low, and the nature of most SAEs was manageable, demonstrating a low-risk safety profile for IS collection even among severely ill children in low-income-country settings. Healthcare providers should monitor oxygen saturation and requirements during and after IS collection, and assess patients prior to reinitiating feeding after the IS procedure, to ensure patient safety. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.
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A Contribution to the Problem of Initiation of a Combustion Source in an Oil-Saturated Bed
NASA Astrophysics Data System (ADS)
Koznacheev, I. A.; Dobrego, K. V.
2013-11-01
The problem on in-situ self-ignition of an oil-saturated bed under the conditions of forced filtration of an oxygen-containing gas has been solved with analytical and numerical methods with account of the burnout of a deficient gas component. The influence of the burnout of this component and of convective removal of heat from the bed on the time of its self-ignition has been determined. Recommendations for the optimum regime of initiation of the self-ignition of the bed with account of variation of the blast flow rate and the oxygen content have been given.
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GIROUX, Marie-Chantal; HÉLIE, Pierre; BURNS, Patrick; VACHON, Pascal
2015-01-01
The main objective of this study was to compare the effects of ketamine and xylazine in aging rats when coadministered intraperitoneally at high anesthetic doses. Three groups (n=6 rats/group) consisting of rats at 3, 6 and 12 months of age were used. During anesthesia, animals were monitored for heart rate, respiratory frequency, blood oxygen saturation, and rectal temperature. The corneal and paw withdrawal reflex were also examined during anesthesia. During anesthesia, withdrawal and corneal reflexes were absent for progressively longer durations with increasing age. Significant decreases in cardiac and respiratory frequency and, blood oxygen saturation occurred for the 6- and 12-month-old animals. Respiratory frequency and blood oxygen saturation returned to normal at the end of the anesthesia; however, the significant decrease in cardiac frequency persisted in the 6- and 12-month-old animals. Rectal temperature was decreased significantly only in the 3-month-old animals. Pulmonary edema and effusion occurred in 50% of the 12-month-old animals. In conclusion, if ketamine-xylazine are used for anesthesia, the doses should be optimized for the age of the subjects prior to initiation of the research project. PMID:25818316
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Iritakenishi, T; Hayashi, Y; Yamanaka, H; Kamibayashi, T; Ueda, K; Mashimo, T
2012-01-01
Inadequate cerebral oxygen balance during cardiopulmonary bypass may cause neuropsychological dysfunction. Milrinone, a phosphodiesterase III inhibitor, augments cerebral blood flow by direct vasodilatation. We conducted a prospective, randomized study in patients undergoing cardiac surgery with cardiopulmonary bypass to clarify the clinical efficacy of milrinone in the imbalance of cerebral oxygen supply and demand during the rewarming period of cardiopulmonary bypass. This is a prospective, randomized and placebo-controlled study. After anesthesia, a 5.5 F fiberoptic oximeter catheter was inserted into the right jugular bulb retrogradely for monitoring the jugular venous oxyhemoglobin saturation (SjO(2)). Patients were randomly assigned to two groups, one receiving a continuous infusion of milrinone, 0.5 µg/kg/min during hypothermic cardiopulmonary bypass, and the other receiving saline as control. Milrinone significantly prevented the reduction of the jugular venous oxyhemoglobin saturation at 10 minutes from the start of rewarming compared with the control group, but did not do so from 10 to 20 minutes after rewarming. Milrinone suppresses the reduction of SjO(2) and improves the balance of cerebral oxygen supply and demand during the early rewarming period of hypothermic cardiopulmonary bypass.
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Physiological responses of preterm newborn infants submitted to classical music therapy.
da Silva, Camila Mendes; Cação, Jessica Marcelle R; Silva, Karin Cristina dos S; Marques, Cassia Fernandes; Merey, Leila Simone F
2013-01-01
To evaluate the physiological effects of music therapy on hospitalized preterm newborns. A noncontrolled clinical trial including 12 newborn infants with gestational age <36 weeks, spontaneously breathing. The preterm infants were submitted to 15-minute sessions of classical music therapy twice a day (morning and afternoon) for three consecutive days. The variables: heart and respiratory rates, oxygen saturation, diastolic and systolic arterial pressures, and body temperature were analyzed before and immediately after each music therapy session. There was a decrease in the heart rate after the second session of music therapy (paired t-test; p=0.002), and an increase at the end of the third session (paired t-test; p=0.005). Respiratory rate decreased during the fourth and fifth sessions (paired t-test; p=0.01 and 0.03, respectively). Regarding oxygen saturation, there was an increase after the fifth session (p=0.008). Comparison of physiological parameters among sessions, for the six studied sessions, showed only that the gain in oxygen saturation during the fifth session was significantly higher than during the sixth one (Tukey's test after variance analysis; p=0.04). Music therapy may modify short-term physiological responses of hospitalized preterm newborn infants.
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Effect of Hypnosis During Administration of Local Anesthesia in Six- to 16-year-old Children.
Oberoi, Jyoti; Panda, Anup; Garg, Iti
2016-01-01
Hypnosis is a tool that can help pediatric dentists allay fear or increase patient cooperation while administering local anesthesia. The purpose of this study was to determine whether hypnosis altered a patient's physical and/or verbal resistance and oxygen saturation or heart rate during administration of local anesthesia. Two hundred six- to 16-year-olds were randomly allocated to either a control group or an experimental group that received hypnotic induction prior to the delivery of local anesthesia. Subjects were monitored for signs of physical or verbal resistance and changes in pulse rate and oxygen saturation at baseline and upon administration of local anesthetic. Children under hypnosis exhibited significantly less resistance to administration of local anesthesia (P<0.05). A bi-serial correlation for age and resistance showed a significant positive correlation (0.337) in the experimental group, indicating that resistance in children increases with age, but none was shown between gender and hypnotic suggestibility. There was a significant difference in pulse rate, attributable to the hypnotic condition (P=.000), but not in oxygen saturation level. Using hypnosis may increase patient cooperation, decrease resistance during painful procedures, and lead to a lower heart rate.
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NASA Technical Reports Server (NTRS)
Gluzek, F.; Mokadam, R. G.; To, I. H.; Stanitz, J. D.; Wollschlager, J.
1979-01-01
A rotating, positive displacement vane pump with an integral boost stage was designed to pump saturated liquid oxygen and liquid hydrogen for auxiliary propulsion system of orbit transfer vehicle. This unit is designed to ingest 10% vapor by volume, contamination free liquid oxygen and liquid hydrogen. The final pump configuration and the predicted performance are included.
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NASA Astrophysics Data System (ADS)
Hou, Chen
Space-filling fractal surfaces play a fundamental role in how organisms function at various levels and in how structure determines function at different levels. In this thesis, we develop a quantitative theory of oxygen transport to and across the surface of the highly branched, space-filling system of alveoli, the fundamental gas exchange unit (acinar airways), in the human lung. Oxygen transport in the acinar airways is by diffusion, and we treat the two steps---diffusion through the branched airways, and transfer across the alveolar membranes---as a stationary diffusion-reaction problem, taking into account that there may be steep concentration gradients between the entrance and remote alveoli (screening). We develop a renormalization treatment of this screening effect and derive an analytic formula for the oxygen current across the cumulative alveolar membrane surface, modeled as a fractal, space-filling surface. The formula predicts the current from a minimum of morphological data of the acinus and appropriate values of the transport parameters, through a number of power laws (scaling laws). We find that the lung at rest operates near the borderline between partial screening and no screening; that it switches to no screening under exercise; and that the computed currents agree with measured values within experimental uncertainties. From an analysis of the computed current as a function of membrane permeability, we find that the space-filling structure of the gas exchanger is simultaneously optimal with respect to five criteria. The exchanger (i) generates a maximum oxygen current at minimum permeability; (ii) 'wastes' a minimum of surface area; (iii) maintains a minimum residence time of oxygen in the acinar airways; (iv) has a maximum fault tolerance to loss of permeability; and (v) generates a maximum current increase when switching from rest to exercise.
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NASA Astrophysics Data System (ADS)
Davies, S.; Sanchez Velasco, L.; Beier, E.; Godinez, V. M.; Barton, E. D.; Tamayo, A.
2016-02-01
Three-dimensional distribution of larval fish habitats was analyzed, from the upper limit of the shallow oxygen minimum zone ( 0.2 mL/L) to the sea surface, in the eastern tropical Pacific Ocean off Mexico in February 2010.The upper limit rises from 250 m depth in the entrance of the Gulf of California to 80 m depth off Cabo Corrientes. Three larval fish habitats were defined statistically: (i) a Gulf of California habitat dominated by Anchoa spp. larvae (epipelagic species), constrained to the oxygenated surface layer (>3.5 mL/L) in and above the thermocline ( 60 m depth), and separated by a salinity front from the Tropical Pacific habitat; (ii) a Tropical Pacific habitat, dominated by Vinciguerria lucetia larvae (mesopelagic species), located throughout the sampled water column, but with the highest abundance in the oxygenated upper layer above the thermocline; (iii) an Oxygen Minimum habitat defined mostly below the thermocline in hypoxic (<1 mL/L; 70 m depth) and anoxic (<0.2 mL/L; 80 m depth) water off Cabo Corrientes. This subsurface hypoxic habitat had the highest species richness and larval abundance, with dominance of Bregmaceros bathymaster, an endemic neritic pelagic species; which was an unexpected result. This maybe associated with the shoaling of the upper limit of the shallow oxygen minimum zone near the coast, a result of the strong costal upwelling detected by the Bakun Index. In this region of strong and semi-continuous coastal upwelling in the eastern tropical Pacific off Mexico, the shallow hypoxic water does not have dramatic effects on the total larval fish abundance but appears to affect species composition.
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14 CFR 91.211 - Supplemental oxygen.
Code of Federal Regulations, 2013 CFR
2013-01-01
... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false Supplemental oxygen. 91.211 Section 91.211... Requirements § 91.211 Supplemental oxygen. (a) General. No person may operate a civil aircraft of U.S. registry... the required minimum flight crew is provided with and uses supplemental oxygen for that part of the...
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14 CFR 91.211 - Supplemental oxygen.
Code of Federal Regulations, 2011 CFR
2011-01-01
... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false Supplemental oxygen. 91.211 Section 91.211... Requirements § 91.211 Supplemental oxygen. (a) General. No person may operate a civil aircraft of U.S. registry... the required minimum flight crew is provided with and uses supplemental oxygen for that part of the...
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14 CFR 91.211 - Supplemental oxygen.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false Supplemental oxygen. 91.211 Section 91.211... Requirements § 91.211 Supplemental oxygen. (a) General. No person may operate a civil aircraft of U.S. registry... the required minimum flight crew is provided with and uses supplemental oxygen for that part of the...
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14 CFR 91.211 - Supplemental oxygen.
Code of Federal Regulations, 2014 CFR
2014-01-01
... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false Supplemental oxygen. 91.211 Section 91.211... Requirements § 91.211 Supplemental oxygen. (a) General. No person may operate a civil aircraft of U.S. registry... the required minimum flight crew is provided with and uses supplemental oxygen for that part of the...
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14 CFR 91.211 - Supplemental oxygen.
Code of Federal Regulations, 2012 CFR
2012-01-01
... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false Supplemental oxygen. 91.211 Section 91.211... Requirements § 91.211 Supplemental oxygen. (a) General. No person may operate a civil aircraft of U.S. registry... the required minimum flight crew is provided with and uses supplemental oxygen for that part of the...
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NASA Astrophysics Data System (ADS)
Kakinuma, Daiki; Tsushima, Yuki; Ohdaira, Kazunori; Yamada, Tadashi
2015-04-01
The objective of the study is to elucidate the waterside environment in the outer moats of Yedo Castle and the downstream of Nihonbashi River in Tokyo. Scince integrated sewage system has been installed in the area around the outer moats of Yedo Castle and the Nihon River basin, when rainfall exceeds more than the sewage treatment capacity, overflowed untreated wastewater is released into the moats and the river. Because the moats is a closed water body, pollutants are deposited to the bottom without outflowing. While reeking offensive odors due to the decomposition, blue-green algae outbreaks affected by the residence time and eluted nutrient causes problems. Scince the Nihonbashi River is a typical tidal river in urban area, the water pollution problems in the river is complicated. This study clarified the characteristics of the water quality in terms of dissolved oxygen saturation through on-site observations. In particular, dissolved oxygen saturation in summer, it is clarified that variations from a supersaturated state due to the variations of horizontal insolation intensity and water temperature up to hypoxic water conditions in the moats. According to previous studies on the water quality of Nihonbashi River, it is clarified that there are three types of variations of dissolved oxygen which desided by rainfall scale. The mean value of dissolved oxygen saturation of all layers has decreased by about 20% at the spring tide after dredging, then it recoveres gradually and become the value before dredging during about a year. Further more, in places where sewage inflows, it is important to developed a ecosystem medel and the applicability of the model. 9 variables including cell quota (intracellular nutrients of phytoplankton) of phosphorus and nitrogen with considerring the nitrification of ammonia nitrogen are used in the model. This model can grasp the sections (such as oxygen production by photosynthesis of phytoplankton, oxygen consumption by respiration of plankton, and bottom mud) of dissolved oxygen concentration.
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Code of Federal Regulations, 2010 CFR
2010-10-01
... .3308 .2328 Dark 10.0P 4.0/10 12.00 .3306 .2162 1 Maximum chroma is not limited. 2 For the colors green and purple, the minimum saturation (chroma) limits for porcelain enamel on metal are lower than for most other surface coatings. Therefore, the minimum chroma limits of these two colors as displayed on...
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Nitrous oxide production in the eastern tropical South Pacific oxygen minimum zone
NASA Astrophysics Data System (ADS)
Ji, Qixing; Altabet, Mark; Arevalo-Martinez, Damian; Bange, Hermann; Ma, Xiao; Marandino, Christa; Sun, Mingshuang; Grundle, Damian
2017-04-01
Nitrous oxide (N2O) is an important climate active trace gas that contributes to both atmospheric warming and ozone destruction, and the ocean is an important source of N2O to the atmosphere. Dissolved oxygen concentrations play an important role in regulating N2O production in the ocean, such that under low oxygen conditions major shifts in the predominant production pathways (i.e. nitrification vs. denitrification) can occur and the magnitude of production may increase substantially. To this end, major oceanic oxygen minimum zones (OMZs) are responsible for a disproportionately high amount of marine N2O production. During the October 2015 ASTRA-OMZ cruise to the eastern tropical South Pacific (ETSP), one of the three major oceanic OMZs, we measured a suite of N2O parameters which included N2O concentrations, N2O production, and natural abundance N2O isotope (i.e. del 15N and del 18O) and isotopomer (i.e. 15N site-preference) signatures. Based on the results from these measurements, our presentation will demonstrate how N2O production and the different production pathways change along the oxygen concentration gradients from the oxygenated surface waters through the oxygen minimum layer. Our data could better constrain the importance of the ETSP-OMZ as source of marine N2O. Results from this work will provide insights into how N2O cycling responds to ocean deoxygenation as a result of climate change.
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Amkhanitskaya, L I; Nikolaeva, G V; Sokolova, N A
2015-07-01
We demonstrated that the vitreous body of one-month-old rabbits becomes a "reservoir" for storage and accumulation of oxygen after exposure to additional oxygenation of the organism (O2 concentrations in inspired gas mixture were 40, 60, 85, and 99%). The higher was O2 concentration in inspired mixture, the higher was oxygen saturation of the blood and vitreous body. O2 concentration of 40% was relatively safe for eye tissues. O2 concentration >60% induced oxygen accumulation in the vitreous body, which can be a provoking factor for the development of oxygen-induced pathologies.
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Peeling, Peter; Andersson, Ramon
2011-01-01
The effect of hyperoxic gas supplementation on the recovery time of oxygen saturation levels (S(a)O(2)), and its effect on perceptual recovery were assessed. Seven national-level kayak athletes completed two laboratory-based ergometer sessions of 6 × 3-min maximal aerobic intervals, with 2 min recovery between repetitions. During each recovery period, athletes either inhaled a hyperoxic gas (99.5 ± 0.2 % F(I)O(2)) or were given no external supplementation (control). Mean power output, stroke rate, heart rate, and ratings of perceived exertion were collected during each interval repetition, and the intensity was matched between trials. During each 2-min recovery period, post-exercise haemoglobin saturation levels were measured via pulse oximetry (S(p)O(2)), and the time taken for the S(p)O(2) to return to pre-exercise values was recorded. Subsequently, a rating of perceived recovery quality was collected. There were no differences in the levels of post-exercise de-saturation between the hyperoxic and control trials (P < 0.05), although the recovery time of S(p)O(2) was significantly faster in the hyperoxic trial (P < 0.05). There was no influence of oxygen supplementation on the athletes' perception of recovery quality. Hyperoxic gas supplementation during the recovery periods between high-intensity intervals substantially improves the recovery time of S(p)O(2) with no likely influence on recovery perception.
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Coe, Kristi; Butler, Mandy; Reavis, Nicole; Klinepeter, Mary Ellen; Purkey, Connie; Oliver, Tonya; Starbuck, Alisa; Griffin, Jennifer; Wilmoth, Cathy; Block, Steven
2006-01-01
Infants born prematurely have a plethora of medical problems. Some have cerebral palsy, resulting in limited mobility, while others require oxygen, hearing aids, and/or glasses for medical problems. Most of these could have been prevented if preterm birth was avoided, but efforts to curb this have been slow. This article discusses how blindness can be prevented in infants born prematurely by accepting lower oxygen saturations when on oxygen in the intensive care nursery.
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Oxygen requirements of separated hybrid catfish female Ictalurus punctatus male I. furcatus eggs
USDA-ARS?s Scientific Manuscript database
Channel catfish Ictalurus punctatus egg masses require ambient water with over 95% air saturation to maintain maximum oxygen consumption as they near hatch. Since hybrid catfish eggs (channel catfish ' X blue catfish I. furcatus ') are often kept separated after fertilization by the addition of full...
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A Theoretical Basis for the Transition to Denitrification at Nanomolar Oxygen Concentrations
NASA Astrophysics Data System (ADS)
Zakem, E.; Follows, M. J.
2016-02-01
Current climate change is likely to expand the size and intensity of marine oxygen minimum zones. How will this affect denitrification rates? Current global biogeochemical models typically prescribe a critical oxygen concentration below which anaerobic activity occurs, rather than resolve the underlying microbial processes. Here, we explore the dynamics of an idealized, simulated anoxic zone in which multiple prokaryotic metabolisms are resolved mechanistically, defined by redox chemistry and biophysical constraints. We first ask, what controls the critical oxygen concentration governing the favorability of aerobic or anaerobic respiration? The predicted threshold oxygen concentration varies as a function of the environment as well as of cell physiology, and lies within the nanomolar range. The model thus provides a theoretical underpinning for the recent observations of nanomolar oxygen concentrations in oxygen minimum zones. In the context of an idealized, two-dimensional intensified upwelling simulation, we also predict denitrification at oxygen concentrations orders of magnitude higher due to physical mixing, reconciling observations of denitrification over a similar range and demonstrating a decoupling of denitrification from the local oxygen concentration. In a sensitivity study with the idealized ocean model, we comment upon the relationship between the volume of anoxic waters and total denitrification.
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Methaemoglobinaemia presenting with status epilepticus.
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
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Effects of Five Nights under Normobaric Hypoxia on Sleep Quality.
Hoshikawa, Masako; Uchida, Sunao; Osawa, Takuya; Eguchi, Kazumi; Arimitsu, Takuma; Suzuki, Yasuhiro; Kawahara, Takashi
2015-07-01
The purpose of this study was to evaluate the effects of five nights' sleep under normobaric hypoxia on ventilatory acclimatization and sleep quality. Seven men initially slept for six nights under normoxia and then for five nights under normobaric hypoxia equivalent to a 2000-m altitude. Nocturnal polysomnograms (PSGs), arterial blood oxygen saturation (SpO2), and respiratory events were recorded on the first and fifth nights under both conditions. The hypoxic ventilatory response (HVR), hypercapnic ventilatory response (HCVR), and resting end-tidal CO2 (resting PETCO2) were measured three times during the experimental period. The duration of slow-wave sleep (SWS: stage N3) and the whole-night delta (1-3 Hz) power of nonrapid eye movement (NREM) sleep EEG decreased on the first night under hypoxia. This hypoxia-induced sleep quality deterioration on the first night was accompanied by a lower mean and minimum SpO2, a longer time spent with SpO2 below 90% (<90% SpO2 time), and more episodes of respiratory disturbance. On the fifth night, the SWS duration and whole-night delta power did not differ between the conditions. Although the mean SpO2 under hypoxia was still lower than under normoxia, the minimum SpO2 increased, and the <90% SpO2 time and number of episodes of respiratory disturbance decreased during the five nights under hypoxia. The HVR increased and resting PETCO2 decreased after five nights under hypoxia. The results suggest that five nights under hypoxia improves the sleep quality. This may be derived from improvements of respiratory disturbances, the minimum SpO2, and <90% SpO2 time.
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Discharge and aftercare in chronic lung disease of the newborn.
Primhak, R A
2003-04-01
This article deals with the discharge planning and continuing care of babies with chronic lung disease of the newborn (CLD), especially those with a continuing oxygen requirement, with some reference to longer term outcome. The pattern of CLD has changed since early descriptions, and the most useful definition for persisting morbidity in a baby with lung disease is a continuing oxygen requirement beyond 36 weeks post-menstrual age. Long-term oxygen therapy to maintain oxygen saturation at a mean of 95% or more and prevent levels below 90% is the cornerstone of management, and with adequate oxygen therapy the excess mortality previously reported in CLD can largely be avoided. Care must be given to the method of assessing oxygen saturation: overnight monitoring using appropriate recording devices is recommended. Exposure to respiratory viruses should be minimized where possible. Metabolic requirements are increased, but if efforts are made to maintain adequate energy input the long-term outlook for catch-up growth in height is good. Respiratory morbidity is increased in early life, but this improves in later childhood, along with lung function and exercise tolerance. Although respiratory symptoms should be treated as they arise, there is no evidence for long-term benefit from any pharmacological intervention in CLD.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Lu-Cun; Friend, C. M.; Fushimi, Rebecca
The activation of molecular O 2as well as the reactivity of adsorbed oxygen species is of central importance in aerobic selective oxidation chemistry on Au-based catalysts. Herein, we address the issue of O 2activation on unsupported nanoporous gold (npAu) catalysts by applying a transient pressure technique, a temporal analysis of products (TAP) reactor, to measure the saturation coverage of atomic oxygen, its collisional dissociation probability, the activation barrier for O 2dissociation, and the facility with which adsorbed O species activate methanol, the initial step in the catalytic cycle of esterification. The results from these experiments indicate that molecular O 2dissociationmore » is associated with surface silver, that the density of reactive sites is quite low, that adsorbed oxygen atoms do not spill over from the sites of activation onto the surrounding surface, and that methanol reacts quite facilely with the adsorbed oxygen atoms. In addition, the O species from O 2dissociation exhibits reactivity for the selective oxidation of methanol but not for CO. The TAP experiments also revealed that the surface of the npAu catalyst is saturated with adsorbed O under steady state reaction conditions, at least for the pulse reaction.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Lu-Cun; Friend, C. M.; Fushimi, Rebecca
2016-01-01
The activation of molecular O 2as well as the reactivity of adsorbed oxygen species is of central importance in aerobic selective oxidation chemistry on Au-based catalysts. Herein, we address the issue of O 2activation on unsupported nanoporous gold (npAu) catalysts by applying a transient pressure technique, a temporal analysis of products (TAP) reactor, to measure the saturation coverage of atomic oxygen, its collisional dissociation probability, the activation barrier for O 2dissociation, and the facility with which adsorbed O species activate methanol, the initial step in the catalytic cycle of esterification. The results from these experiments indicate that molecular O 2dissociationmore » is associated with surface silver, that the density of reactive sites is quite low, that adsorbed oxygen atoms do not spill over from the sites of activation onto the surrounding surface, and that methanol reacts quite facilely with the adsorbed oxygen atoms. In addition, the O species from O 2dissociation exhibits reactivity for the selective oxidation of methanol but not for CO. The TAP experiments also revealed that the surface of the npAu catalyst is saturated with adsorbed O under steady state reaction conditions, at least for the pulse reaction.« less
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Wang, Cai-Xia; Wang, Jian; Chen, Yuan-Yuan; Wang, Jia-Ni; Yu, Xin; Yang, Feng; Sun, Si-Yu
2016-12-14
To evaluate the efficacy and safety of nitrous oxide-sedated endoscopic ultrasound-guided fine needle aspiration. Enrolled patients were divided randomly into an experimental group (inhalation of nitrous oxide) and a control group (inhalation of pure oxygen) and heart rate, blood oxygen saturation, blood pressure, electrocardiogram (ECG) changes, and the occurrence of complications were monitored and recorded. All patients and physicians completed satisfaction questionnaires about the examination and scored the process using a visual analog scale. There was no significant difference in heart rate, blood oxygen saturation, blood pressure, ECG changes, or complication rate between the two groups of patients ( P > 0.05). However, patient and physician satisfaction were both significantly higher in the nitrous oxide compared with the control group ( P < 0.05). Nitrous oxide-sedation is a safe and effective option for patients undergoing endoscopic ultrasound-guided fine needle aspiration.
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Oxygen index evaluation of fire-retardant-treated wood
Robert H. White
1979-01-01
The applicability of using the oxygen index test (ASTM D 2863-76) to obtain an indication of the relative flammability of fire-retardant- treated wood products was investigated. The oxygen index is the minimum percentage oxygen that is required to maintain flaming combustion of a specimen under specified laboratory conditions. Within the plastics industry, the test is...
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Kim, Eunjong; Lee, Dong-Hyun; Won, Seunggun; Ahn, Heekwon
2016-01-01
Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg O2/g VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS’s optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust’s coarse particle size and bulking effect. PMID:26954138
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Kim, Eunjong; Lee, Dong-Hyun; Won, Seunggun; Ahn, Heekwon
2016-05-01
Moisture content influences physiological characteristics of microbes and physical structure of solid matrices during composting of animal manure. If moisture content is maintained at a proper level, aerobic microorganisms show more active oxygen consumption during composting due to increased microbial activity. In this study, optimum moisture levels for composting of two bedding materials (sawdust, rice hull) and two different mixtures of bedding and beef manure (BS, Beef cattle manure+sawdust; BR, Beef cattle manure+rice hull) were determined based on oxygen uptake rate measured by a pressure sensor method. A broad range of oxygen uptake rates (0.3 to 33.3 mg O2/g VS d) were monitored as a function of moisture level and composting feedstock type. The maximum oxygen consumption of each material was observed near the saturated condition, which ranged from 75% to 98% of water holding capacity. The optimum moisture content of BS and BR were 70% and 57% on a wet basis, respectively. Although BS's optimum moisture content was near saturated state, its free air space kept a favorable level (above 30%) for aerobic composting due to the sawdust's coarse particle size and bulking effect.
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NASA Astrophysics Data System (ADS)
Xu, Ya; Sakurai, Junya; Teraoka, Yuden; Yoshigoe, Akitaka; Demura, Masahiko; Hirano, Toshiyuki
2017-01-01
The initial oxidation behavior of a clean Ni3Al (210) surface was studied at 300 K using a supersonic O2 molecular beam (O2 SSMB) having an O2 translational energy of 2.3 eV, and real-time photoemission spectroscopy performed with high-brilliance synchrotron radiation. The evolution behaviors of the O 1s, Ni 2p, Al 2p, and Ni 3p spectra were examined during irradiation with the O2 SSMB. The spectral analysis revealed that both the Al atoms and the Ni atoms on the surface were oxidized; however, the oxidation of Al progressed much faster than that of Ni. The oxidation of Al began to occur and AlOx was formed at an oxygen coverage of 0.26 monolayer (ML) (1 ML was defined as the atomic density of the Ni3Al (210) surface) and saturated at an oxygen coverage of 2.5 ML. In contrast, the oxidation of Ni commenced a little late at an oxygen coverage of 1.6 ML and slowly progressed to saturation, which occurred at an oxygen coverage of 4.89 ML.
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NASA Astrophysics Data System (ADS)
Bartholomeus, Ruud P.; Witte, Jan-Philip M.; van Bodegom, Peter M.; van Dam, Jos C.; Aerts, Rien
2008-10-01
SummaryEffects of insufficient soil aeration on the functioning of plants form an important field of research. A well-known and frequently used utility to express oxygen stress experienced by plants is the Feddes-function. This function reduces root water uptake linearly between two constant pressure heads, representing threshold values for minimum and maximum oxygen deficiency. However, the correctness of this expression has never been evaluated and constant critical values for oxygen stress are likely to be inappropriate. On theoretical grounds it is expected that oxygen stress depends on various abiotic and biotic factors. In this paper, we propose a fundamentally different approach to assess oxygen stress: we built a plant physiological and soil physical process-based model to calculate the minimum gas filled porosity of the soil ( ϕgas_min) at which oxygen stress occurs. First, we calculated the minimum oxygen concentration in the gas phase of the soil needed to sustain the roots through (micro-scale) diffusion with just enough oxygen to respire. Subsequently, ϕgas_min that corresponds to this minimum oxygen concentration was calculated from diffusion from the atmosphere through the soil (macro-scale). We analyzed the validity of constant critical values to represent oxygen stress in terms of ϕgas_min, based on model simulations in which we distinguished different soil types and in which we varied temperature, organic matter content, soil depth and plant characteristics. Furthermore, in order to compare our model results with the Feddes-function, we linked root oxygen stress to root water uptake (through the sink term variable F, which is the ratio of actual and potential uptake). The simulations showed that ϕgas_min is especially sensitive to soil temperature, plant characteristics (root dry weight and maintenance respiration coefficient) and soil depth but hardly to soil organic matter content. Moreover, ϕgas_min varied considerably between soil types and was larger in sandy soils than in clayey soils. We demonstrated that F of the Feddes-function indeed decreases approximately linearly, but that actual oxygen stress already starts at drier conditions than according to the Feddes-function. How much drier is depended on the factors indicated above. Thus, the Feddes-function might cause large errors in the prediction of transpiration reduction and growth reduction through oxygen stress. We made our method easily accessible to others by implementing it in SWAP, a user-friendly soil water model that is coupled to plant growth. Since constant values for ϕgas_min in plant and hydrological modeling appeared to be inappropriate, an integrated approach, including both physiological and physical processes, should be used instead. Therefore, we advocate using our method in all situations where oxygen stress could occur.
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Arnardottir, Erna S.; Maislin, Greg; Schwab, Richard J.; Staley, Bethany; Benediktsdottir, Bryndis; Olafsson, Isleifur; Juliusson, Sigurdur; Romer, Micah; Gislason, Thorarinn; Pack, Allan I.
2012-01-01
Study Objectives: To assess the relative roles and interaction of obstructive sleep apnea (OSA) severity and obesity on interleukin-6 (IL-6) and C-reactive protein (CRP) levels. Design: Cross-sectional cohort. Setting: The Icelandic Sleep Apnea Cohort. Participants: 454 untreated OSA patients (380 males and 74 females), mean ± standard deviation age 54.4 ± 10.6 yr. Interventions: N/A. Measurements and Results: Participants underwent a sleep study, abdominal magnetic resonance imaging to measure total abdominal and visceral fat volume, and had fasting morning IL-6 and CRP levels measured in serum. A significantly higher correlation was found for BMI than visceral fat volume with CRP and IL-6 levels. Oxygen desaturation index, hypoxia time, and minimum oxygen saturation (SaO2) significantly correlated with IL-6 and CRP levels, but apnea-hypopnea index did not. When stratified by body mass index (BMI) category, OSA severity was associated with IL-6 levels in obese participants only (BMI > 30 kg/m2). A multiple linear regression model with interaction terms showed an independent association of OSA severity with IL-6 levels and an interaction between OSA severity and BMI, i.e., degree of obesity altered the relationship between OSA and IL-6 levels. An independent association of OSA severity with CRP levels was found for minimum SaO2 only. A similar interaction of OSA severity and BMI on CRP levels was found for males and postmenopausal women. Conclusions: OSA severity is an independent predictor of levels of IL-6 and CRP but interacts with obesity such that this association is found only in obese patients. Citation: Arnardottir ES; Maislin G; Schwab RJ; Staley B; Benediktsdottir B; Olafsson I; Juliusson S; Romer M; Gislason T; Pack AI. The interaction of obstructive sleep apnea and obesity on the inflammatory markers c-reactive protein and interleukin-6: the Icelandic Sleep Apnea Cohort. SLEEP 2012;35(7):921-932. PMID:22754038
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2011-01-01
Introduction Succinylcholine and rocuronium are widely used to facilitate rapid sequence induction (RSI) intubation in intensive care. Concerns relate to the side effects of succinylcholine and to slower onset and inferior intubation conditions associated with rocuronium. So far, succinylcholine and rocuronium have not been compared in an adequately powered randomized trial in intensive care. Accordingly, the aim of the present study was to compare the incidence of hypoxemia after rocuronium or succinylcholine in critically ill patients requiring an emergent RSI. Methods This was a prospective randomized controlled single-blind trial conducted from 2006 to 2010 at the University Hospital of Basel. Participants were 401 critically ill patients requiring emergent RSI. Patients were randomized to receive 1 mg/kg succinylcholine or 0.6 mg/kg rocuronium for neuromuscular blockade. The primary outcome was the incidence of oxygen desaturations defined as a decrease in oxygen saturation ≥ 5%, assessed by continuous pulse oxymetry, at any time between the start of the induction sequence and two minutes after the completion of the intubation. A severe oxygen desaturation was defined as a decrease in oxygen saturation ≥ 5% leading to a saturation value of ≤ 80%. Results There was no difference between succinylcholine and rocuronium regarding oxygen desaturations (succinylcholine 73/196; rocuronium 66/195; P = 0.67); severe oxygen desaturations (succinylcholine 20/196; rocuronium 20/195; P = 1.0); and extent of oxygen desaturations (succinylcholine -14 ± 12%; rocuronium -16 ± 13%; P = 0.77). The duration of the intubation sequence was shorter after succinycholine than after rocuronium (81 ± 38 sec versus 95 ± 48 sec; P = 0.002). Intubation conditions (succinylcholine 8.3 ± 0.8; rocuronium 8.2 ± 0.9; P = 0.7) and failed first intubation attempts (succinylcholine 32/200; rocuronium 36/201; P = 1.0) did not differ between the groups. Conclusions In critically ill patients undergoing emergent RSI, incidence and severity of oxygen desaturations, the quality of intubation conditions, and incidence of failed intubation attempts did not differ between succinylcholine and rocuronium. Trial Registration ClinicalTrials.gov, number NCT00355368. PMID:21846380
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NASA Astrophysics Data System (ADS)
Fetler, Bayard Keith
1993-01-01
Nuclear magnetic resonance (NMR) offers a potential method for making measurements of the percent oxygenation of hemoglobin (Hb) in living tissue non-invasively. As a demonstration of the feasibility of such measurements, we measured the percent oxygenation of Hb in red blood cells (erythrocytes) using resonances in the proton-NMR (^1H-NMR) spectrum which are characteristic of oxyhemoglobin (oxy-Hb) and deoxyhemoglobin (deoxy-Hb), and are due to the unique magnetic properties of these molecules. To perform these measurements, we developed a new NMR method of selectively exciting signals in a region of interest with uniform phase and amplitude, while suppressing the signal of the water resonance. With this method, we are able to make exact calculations distinguishing between uniform phase excitation produced at large flip-angles using the non-linear properties of the Bloch equations, and uniform phase excitation produced at small flip-angles using asymmetric pulse excitation functions. We measured the percent oxygenation of three characteristic ^1H-NMR resonances of Hb: two from deoxy-Hb, originating from the N_delta H protons of histidine residue F8, which occur at different frequencies for the alpha and beta chains of Hb; and one from oxy-Hb, originating from the gamma_2 -CH_3 protons of valine residue E11. We performed experiments both on fresh erythrocytes and on erythrocytes depleted of 2,3-diphosphoglycerate (2,3-DPG), and found that oxygen is more tightly bound to Hb in the former case. In both fresh and 2,3-DPG-depleted samples, we found that: (i) from the deoxy-Hb marker resonances, there is a small but significant difference in the oxygen saturation between the alpha and beta chains; (ii) the decrease in the areas of the deoxy-Hb marker resonances correlates well with the increase in the percent oxygenation of Hb as measured optically; (iii) the area of the oxy-Hb marker resonance may be up to ~15% less than the optically measured Hb saturation. We are thus able to demonstrate the feasibility and validity of using this method to measure the oxygen saturation of Hb using ^1H-NMR.
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2012-01-01
Background Non-enzymatic glycation increases hemoglobin-oxygen affinity and reduces oxygen delivery to tissues by altering the structure and function of hemoglobin. Objectives We investigated whether an elevated blood concentration of glycosylated hemoglobin (HbA1c) could induce falsely high pulse oximeter oxygen saturation (SpO2) in type 2 diabetic patients during mechanical ventilation or oxygen therapy. Methods Arterial oxygen saturation (SaO2) and partial pressure of oxygen (PO2) were determined with simultaneous monitoring of SpO2 in 261 type 2 diabetic patients during ventilation or oxygen inhalation. Results Blood concentration of HbA1c was >7% in 114 patients and ≤ 7% in 147 patients. Both SaO2 (96.2 ± 2.9%, 95% confidence interval [CI] 95.7-96.7% vs. 95.1 ± 2.8%, 95% CI 94.7-95.6%) and SpO2 (98.0 ± 2.6%, 95% CI 97.6-98.5% vs. 95.3 ± 2.8%, 95% CI 94.9-95.8%) were significantly higher in patients with HbA1c >7% than in those with HbA1c ≤ 7% (Data are mean ± SD, all p < 0.01), but PO2 did not significantly differ between the two groups. Bland-Altman analysis demonstrated a significant bias between SpO2 and SaO2 (1.83 ±0.55%, 95% CI 1.73% -1.94%) and limits of agreement (0.76% and 2.92%) in patients with HbA1c >7%. The differences between SpO2 and SaO2 correlated closely with blood HbA1c levels (Pearson’s r = 0.307, p < 0.01). Conclusions Elevated blood HbA1c levels lead to an overestimation of SaO2 by SpO2, suggesting that arterial blood gas analysis may be needed for type 2 diabetic patients with poor glycemic control during the treatment of hypoxemia. PMID:22985301
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Pu, Li Jin; Shen, Ying; Lu, Lin; Zhang, Rui Yan; Zhang, Qi; Shen, Wei Feng
2012-09-17
Non-enzymatic glycation increases hemoglobin-oxygen affinity and reduces oxygen delivery to tissues by altering the structure and function of hemoglobin. We investigated whether an elevated blood concentration of glycosylated hemoglobin (HbA1c) could induce falsely high pulse oximeter oxygen saturation (SpO2) in type 2 diabetic patients during mechanical ventilation or oxygen therapy. Arterial oxygen saturation (SaO2) and partial pressure of oxygen (PO2) were determined with simultaneous monitoring of SpO2 in 261 type 2 diabetic patients during ventilation or oxygen inhalation. Blood concentration of HbA1c was >7% in 114 patients and ≤ 7% in 147 patients. Both SaO2 (96.2 ± 2.9%, 95% confidence interval [CI] 95.7-96.7% vs. 95.1 ± 2.8%, 95% CI 94.7-95.6%) and SpO2 (98.0 ± 2.6%, 95% CI 97.6-98.5% vs. 95.3 ± 2.8%, 95% CI 94.9-95.8%) were significantly higher in patients with HbA1c >7% than in those with HbA1c ≤ 7% (Data are mean ± SD, all p < 0.01), but PO2 did not significantly differ between the two groups. Bland-Altman analysis demonstrated a significant bias between SpO2 and SaO2 (1.83 ±0.55%, 95% CI 1.73% -1.94%) and limits of agreement (0.76% and 2.92%) in patients with HbA1c >7%. The differences between SpO2 and SaO2 correlated closely with blood HbA1c levels (Pearson's r = 0.307, p < 0.01). Elevated blood HbA1c levels lead to an overestimation of SaO2 by SpO2, suggesting that arterial blood gas analysis may be needed for type 2 diabetic patients with poor glycemic control during the treatment of hypoxemia.
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Norman, Daniel; Bardwell, Wayne A; Arosemena, Farah; Nelesen, Richard; Mills, Paul J; Loredo, Jose S; Lavine, Joel E; Dimsdale, Joel E
2008-01-01
Nonalcoholic fatty liver disease (NAFLD) is a disorder that often presents with elevated serum aminotransferase levels. Although it has classically been linked with the metabolic syndrome, recent studies suggest NAFLD may also be associated with obstructive sleep apnea (OSA). This study evaluates the association between serum aminotransferase levels and factors connected with: either the metabolic syndrome (elevated body mass index [BMI], lipid profile, blood pressure, fasting glucose), or with OSA severity (apnea hypopnea index, lowest oxygen saturation level, oxygen desaturation index, percent of time below 90% saturation [%T<90]). Retrospective case series. 109 adult patients with OSA at a university hospital general clinical research center. Markers of hypoxia (lowest oxygen saturation level and %T<90), correlated significantly with aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels (Pearson's r = -0.31 to -0.38, P <0.003), while apnea hypopnea index, body mass index, blood pressure, fasting glucose, triglyceride, and cholesterol levels did not. Hierarchical linear regression was then done to determine the best predictors of aminotransferase levels. Markers of metabolic syndrome were entered as one block and markers of sleep apnea as another. Regression analyses explained 16.3% of the variance in AST and 18.9% of the variance in ALT, with %T<90 playing the largest role. In patients with obstructive sleep apnea, serum aminotransferase levels are better predicted by markers of oxygen desaturation than by factors traditionally associated with the metabolic syndrome.
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Hadjistassou, Constantinos; Moyle, Keri; Ventikos, Yiannis
2016-01-01
The advent of functional MRI in the mid-1990s has catalyzed progress pertaining to scientific discoveries in neuroscience. With the prospect of elucidating the physiological aspect of the Blood Oxygenation Level Dependent (BOLD) effect we present a computational capillary-tissue system capable of mapping venous hemoglobin saturation— a marker of the BOLD hemodynamic response. Free and facilitated diffusion and convection for hemoglobin and oxygen are considered in the radial and axial directions. Hemoglobin reaction kinetics are governed by the oxyhemoglobin dissociation curve. Brain activation, mimicked by dynamic transitions in cerebral blood velocity (CBv) and oxidative metabolism (CMRO2), is simulated by normalized changes in m = (ΔCBv/CBv)/(ΔCMRO2/CMRO2) of values 2, 3 and 4. Venous hemoglobin saturation profiles and peak oxygenation results, for m = 2, based upon a 50% and a 25% increase in CBv and CMRO2, respectively, lie within physiological limits exhibiting excellent correlation with the BOLD signal, for short-duration stimuli. Our analysis suggests basal CBv and CMRO2 values of 0.6 mm/s and 200 μmol/100g/min. Coupled CBv and CMRO2 responses, for m = 3 and m = 4, overestimate peak hemoglobin saturation, confirming the system’s responsiveness to changes in hematocrit, CBv and CMRO2. Finally, factoring in neurovascular effects, we show that no initial dip will be observed unless there is a time delay in the onset of increased CBv relative to CMRO2. PMID:26939128
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Using the MWC model to describe heterotropic interactions in hemoglobin
Rapp, Olga
2017-01-01
Hemoglobin is a classical model allosteric protein. Research on hemoglobin parallels the development of key cooperativity and allostery concepts, such as the ‘all-or-none’ Hill formalism, the stepwise Adair binding formulation and the concerted Monod-Wymann-Changuex (MWC) allosteric model. While it is clear that the MWC model adequately describes the cooperative binding of oxygen to hemoglobin, rationalizing the effects of H+, CO2 or organophosphate ligands on hemoglobin-oxygen saturation using the same model remains controversial. According to the MWC model, allosteric ligands exert their effect on protein function by modulating the quaternary conformational transition of the protein. However, data fitting analysis of hemoglobin oxygen saturation curves in the presence or absence of inhibitory ligands persistently revealed effects on both relative oxygen affinity (c) and conformational changes (L), elementary MWC parameters. The recent realization that data fitting analysis using the traditional MWC model equation may not provide reliable estimates for L and c thus calls for a re-examination of previous data using alternative fitting strategies. In the current manuscript, we present two simple strategies for obtaining reliable estimates for MWC mechanistic parameters of hemoglobin steady-state saturation curves in cases of both evolutionary and physiological variations. Our results suggest that the simple MWC model provides a reasonable description that can also account for heterotropic interactions in hemoglobin. The results, moreover, offer a general roadmap for successful data fitting analysis using the MWC model. PMID:28793329
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Sokoloff, Max D; Plegue, Melissa A; Chervin, Ronald D; Barks, John D E; Shellhaas, Renée A
2015-07-01
Near-infrared spectroscopy (NIRS) measures oxygen metabolism and is increasingly used for monitoring critically ill neonates. The implications of NIRS-recorded data in this population are poorly understood. We evaluated NIRS monitoring for neonates with seizures. In neonates monitored with video-electroencephalography, NIRS-measured cerebral regional oxygen saturation (rSO2) and systemic O2 saturation were recorded every 5 s. Mean rSO2 was extracted for 1-h blocks before, during, and after phenobarbital doses. For each electrographic seizure, mean rSO2 was extracted for a period of three times the duration of the seizure before and after the ictal pattern, as well as during the seizure. Linear mixed models were developed to assess the impact of phenobarbital administration and of seizures on rSO2 and fractional tissue oxygen extraction. For 20 neonates (estimated gestational age: 39.6 ± 1.5 wk), 61 phenobarbital doses and 40 seizures were analyzed. Cerebral rSO2 rose (P = 0.005), and fractional tissue oxygen extraction declined (P = 0.018) with increasing phenobarbital doses. rSO2 declined during seizures, compared with baseline and postictal phases (baseline 81.2 vs. ictal 77.7 vs. postictal 79.4; P = 0.004). Fractional tissue oxygen extraction was highest during seizures (P = 0.002). Cerebral oxygen metabolism decreases after phenobarbital administration and increases during seizures. These small, but clear, changes in cerebral oxygen metabolism merit assessment for potential clinical impact.
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Design of an Oximeter Based on LED-LED Configuration and FPGA Technology
Stojanovic, Radovan; Karadaglic, Dejan
2013-01-01
A fully digital photoplethysmographic (PPG) sensor and actuator has been developed. The sensing circuit uses one Light Emitting Diode (LED) for emitting light into human tissue and one LED for detecting the reflectance light from human tissue. A Field Programmable Gate Array (FPGA) is used to control the LEDs and determine the PPG and Blood Oxygen Saturation (SpO2). The configurations with two LEDs and four LEDs are developed for measuring PPG signal and Blood Oxygen Saturation (SpO2). N-LEDs configuration is proposed for multichannel SpO2 measurements. The approach resulted in better spectral sensitivity, increased and adjustable resolution, reduced noise, small size, low cost and low power consumption. PMID:23291575
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Polysomnographic Oxygen Saturation Findings for Preteen Children versus Adolescents.
Wiebracht, Nathan D; He, Shan; Cotton, Colin; Meinzen-Derr, Jareen; Shott, Gordon; Smith, David F; McConnell, Keith B; Ishman, Stacey L
2018-01-01
Objective Home oximetry is commonly used to screen for obstructive sleep apnea (OSA) in children; however, normal oxygen desaturation levels by disease severity are not well known. It was our objective to determine if oxygen saturation levels differed by OSA severity category in children and if these differences were similar for preteen children and adolescents. Study Design Retrospective case series of children undergoing polysomnography from September 2011 to July 2015. Setting Tertiary pediatric hospital. Subjects and Methods Six- to 18-year-olds (preteen, 6-12 years old; adolescent, 13-18 years old). Chi-square, Wilcoxon rank sum test, and Kruskal-Wallis testing were used to compare variables between age groups. Results The study included 342 children with a mean age of 11.3 ± 2.4 years (range, 6.5-17.5) and a mean body mass index of 25.6 ± 9.2 kg/m 2 (78 ± 29 percentile); 61% were white, 35% were black, and 4% were other or unknown. Of the children, 48% were female, and this was not a significant difference between age groups ( P = .81). Overall, 50% of the children had no OSA, 32% mild, 10% moderate, and 8% severe. When compared with the younger children, the adolescents had a longer sleep time ( P = .014) and a higher mean obstructive apnea-hypopnea index (3.53 ± 5.1 vs 3.03 ± 6.1 events per hour, P = .02). The 3% and 4% oxygen desaturation indices were not significantly different between age groups when accounting for OSA severity. Conclusion Adolescents have longer sleep times and higher obstructive apnea-hypopnea indexes than preteens, but oxygen saturations and desaturation indices were similar. This supports current triage algorithms for children with OSA, as we found no significant age-based differences.
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Kussman, Barry D; Gauvreau, Kimberlee; DiNardo, James A; Newburger, Jane W; Mackie, Andrew S; Booth, Karen L; del Nido, Pedro J; Roth, Stephen J; Laussen, Peter C
2007-03-01
The proposed physiologic advantage of the modified Norwood procedure using a right ventricle-pulmonary artery conduit to supply pulmonary blood flow, compared with a modified Blalock-Taussig shunt, is reduced runoff from the systemic-to-pulmonary circulation during diastole, resulting in a higher diastolic blood pressure and improved systemic perfusion. We hypothesized that the modified Norwood procedure is associated with improved cerebral perfusion and oxygenation. Transcranial Doppler sonography and near-infrared spectroscopy were performed in neonates undergoing the Norwood procedure with either a modified Blalock-Taussig shunt (n = 14) or right ventricle-pulmonary artery conduit (n = 13). Diastolic blood pressure was significantly higher in the right ventricle-pulmonary artery group at 6 hours after bypass (46 +/- 7 vs 40 +/- 4 mm Hg; P = .03), on postoperative day 1 (45 +/- 6 vs 37 +/- 5 mm Hg; P = .002), and on postoperative day 2 (46 +/- 7 vs 37 +/- 4 mm Hg; P = .001). Cerebral diastolic blood flow velocity did not differ significantly between groups at any time point or over time, but cerebral systolic blood flow velocity was higher over time in the Blalock-Taussig group (P = .01). No significant differences in regional cerebral oxygen saturation were found between groups at baseline or after bypass. Blood flow velocities and cerebral oxygen saturation did not differ significantly according to use of regional low-flow perfusion. The higher diastolic blood pressure after the modified Norwood procedure is not associated with higher cerebral blood flow velocities or regional cerebral oxygen saturation. This may imply an equal vulnerability to the cerebral injury associated with hemodynamic instability in the early postoperative period.
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Papadopoulos, Georgios; Dounousi, Evangelia; Papathanasiou, Athanasios; Papathanakos, Georgios; Tzimas, Petros
2013-07-01
Cerebral tissue regional oxygen saturation (rSO2) through near-infrared spectroscopy (NIRS) is a method for non-invasive monitoring of cerebral tissue oxygenation. However, nowadays there is limited information on the level of cerebral tissue oxygenation in dialyzed end-stage renal disease (ESRD) surgical patients. The aim of this observational study was to evaluate the baseline cerebral rSO2 values, to compare values between hemodialysis (HD) and peritoneal dialysis (PD) patients and identify risk factors that could predict cerebral tissue oxygenation in these patients. Thirty-two ESRD patients (≥18 years old), scheduled to undergo elective minor or major surgery, were enrolled. Patients were allocated in two groups according to dialysis modality. Twenty-three patients were treated with HD and nine were treated with PD. Demographic and clinical characteristics, comorbidities and arterial hemoglobin oxygen saturation (SpO2) of the study population were recorded. Patients who were treated with HD had significant lower baseline rSO2 values compared with PD patients [median, 50% (28-63) vs. 63% (45-69), p = 0.002]. Hierarchical linear regression model analysis showed that preoperative Hb and SpO2 were positive predictive variables (B = 0.353, p = 0.01 and B = 0.375, p = 0.009, respectively) for rSO2. Moreover, dialysis modality was independent predictor for baseline rSO2. The modality of dialysis remained an independent predictor for rSO2 after controlling for the other significant variables (B = 0.291, p = 0.032) and PD was associated with higher baseline values of rSO2. In conclusion, ESRD surgical patients undergoing PD treatment appear to have significantly higher baseline cerebral tissue saturation values compared with HD.
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NASA Astrophysics Data System (ADS)
Ewerlöf, Maria; Larsson, Marcus; Salerud, E. Göran
2017-02-01
Hyperspectral imaging (HSI) can estimate the spatial distribution of skin blood oxygenation, using visible to near-infrared light. HSI oximeters often use a liquid-crystal tunable filter, an acousto-optic tunable filter or mechanically adjustable filter wheels, which has too long response/switching times to monitor tissue hemodynamics. This work aims to evaluate a multispectral snapshot imaging system to estimate skin blood volume and oxygen saturation with high temporal and spatial resolution. We use a snapshot imager, the xiSpec camera (MQ022HG-IM-SM4X4-VIS, XIMEA), having 16 wavelength-specific Fabry-Perot filters overlaid on the custom CMOS-chip. The spectral distribution of the bands is however substantially overlapping, which needs to be taken into account for an accurate analysis. An inverse Monte Carlo analysis is performed using a two-layered skin tissue model, defined by epidermal thickness, haemoglobin concentration and oxygen saturation, melanin concentration and spectrally dependent reduced-scattering coefficient, all parameters relevant for human skin. The analysis takes into account the spectral detector response of the xiSpec camera. At each spatial location in the field-of-view, we compare the simulated output to the detected diffusively backscattered spectra to find the best fit. The imager is evaluated for spatial and temporal variations during arterial and venous occlusion protocols applied to the forearm. Estimated blood volume changes and oxygenation maps at 512x272 pixels show values that are comparable to reference measurements performed in contact with the skin tissue. We conclude that the snapshot xiSpec camera, paired with an inverse Monte Carlo algorithm, permits us to use this sensor for spatial and temporal measurement of varying physiological parameters, such as skin tissue blood volume and oxygenation.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Detwiler, Russell L.; Glass, Robert J.; Pringle, Scott E.
Understanding of single and multi-phase flow and transport in fractures can be greatly enhanced through experimentation in transparent systems (analogs or replicas) where light transmission techniques yield quantitative measurements of aperture, solute concentration, and phase saturation fields. Here we quanti@ aperture field measurement error and demonstrate the influence of this error on the results of flow and transport simulations (hypothesized experimental results) through saturated and partially saturated fractures. find that precision and accuracy can be balanced to greatly improve the technique and We present a measurement protocol to obtain a minimum error field. Simulation results show an increased sensitivity tomore » error as we move from flow to transport and from saturated to partially saturated conditions. Significant sensitivity under partially saturated conditions results in differences in channeling and multiple-peaked breakthrough curves. These results emphasize the critical importance of defining and minimizing error for studies of flow and transpoti in single fractures.« less
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USDA-ARS?s Scientific Manuscript database
We present near-infrared spectroscopy measurement of absolute cerebral hemoglobin concentration and saturation in a large sample of 36 healthy elderly (mean age, 85 ± 6 years) and 19 young adults (mean age, 28 ± 4 years). Non-invasive measurements were obtained on the forehead using a commercially a...
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Module for Oxygenating Water without Generating Bubbles
NASA Technical Reports Server (NTRS)
Gonzalez-Martin, Anuncia; Sidik, Reyimjan; Kim, Jinseong
2004-01-01
A module that dissolves oxygen in water at concentrations approaching saturation, without generating bubbles of oxygen gas, has been developed as a prototype of improved oxygenators for water-disinfection and water-purification systems that utilize photocatalyzed redox reactions. Depending on the specific nature of a water-treatment system, it is desirable to prevent the formation of bubbles for one or more reasons: (1) Bubbles can remove some organic contaminants from the liquid phase to the gas phase, thereby introducing a gas-treatment problem that complicates the overall water-treatment problem; and/or (2) in some systems (e.g., those that must function in microgravity or in any orientation in normal Earth gravity), bubbles can interfere with the flow of the liquid phase. The present oxygenation module (see Figure 1) is a modified version of a commercial module that contains >100 hollow polypropylene fibers with a nominal pore size of 0.05 m and a total surface area of 0.5 m2. The module was originally designed for oxygenation in a bioreactor, with no water flowing around or inside the tubes. The modification, made to enable the use of the module to oxygenate flowing water, consisted mainly in the encapsulation of the fibers in a tube of Tygon polyvinyl chloride (PVC) with an inside diameter of 1 in. (approx.=25 mm). In operation, water is pumped along the insides of the hollow fibers and oxygen gas is supplied to the space outside the hollow tubes inside the PVC tube. In tests, the pressure drops of water and oxygen in the module were found to be close to zero at water-flow rates ranging up to 320 mL/min and oxygen-flow rates up to 27 mL/min. Under all test conditions, no bubbles were observed at the water outlet. In some tests, flow rates were chosen to obtain dissolved-oxygen concentrations between 25 and 31 parts per million (ppm) . approaching the saturation level of approx.=35 ppm at a temperature of 20 C and pressure of 1 atm (approx.=0.1 MPa). As one would expect, it was observed that the time needed to bring a flow of water from an initial low dissolved-oxygen concentration (e.g., 5 ppm) to a steady high dissolved-oxygen concentration at or near the saturation level depends on the rates of flow of both oxygen and water, among other things. Figure 2 shows the results of an experiment in which a greater flow of oxygen was used during the first few tens of minutes to bring the concentration up to approx.=25 ppm, then a lesser flow was used to maintain the concentration.
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Exposure to air pollution increases the risk of cardiovascular morbidity and mortality, especially in individuals with pre-existing cardiovascular disease. Recent studies link exposure to air pollution with reduced blood oxygen saturation suggesting that hypoxia is a potential me...
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Point-of-care instrument for monitoring tissue health during skin graft repair
NASA Astrophysics Data System (ADS)
Gurjar, R. S.; Seetamraju, M.; Zhang, J.; Feinberg, S. E.; Wolf, D. E.
2011-06-01
We have developed the necessary theoretical framework and the basic instrumental design parameters to enable mapping of subsurface blood dynamics and tissue oxygenation for patients undergoing skin graft procedures. This analysis forms the basis for developing a simple patch geometry, which can be used to map by diffuse optical techniques blood flow velocity and tissue oxygenation as a function of depth in subsurface tissue.skin graft, diffuse correlation analysis, oxygen saturation.
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NASA Astrophysics Data System (ADS)
Montes, I.; Dewitte, B.; Gutknecht, E.; Paulmier, A.; Dadou, I.; Oschlies, A.; Garçon, V. C.
2015-12-01
The Eastern Tropical South Pacific encompasses one of the most extended Oxygen Minimum zones, which is mainly maintained by a combination of sluggish circulation and high biological productivity in the surface layer leading to elevate organic matter decomposition consuming dissolved oxygen. Low-oxygen areas are important not only for macroorganisms that cannot survive in oxygen-poor conditions, but also because of special biogeochemical processes occurring at low oxygen concentrations. In particular, a large fraction of oceanic nitrogen-loss occurs in these areas via anaerobic microbial processes. These include denitrification and axammox that both lead to a net loss of fixed nitrogen once oxygen concentrations have fallen below some threshold of a few umol/l. Recently it has been found that eddies may act as nitrogen-loss hotspots, possibly by shielding enclosed water parcels from lateral mixing with better ventilated oxygen-richer waters outside the eddies. Here we used a regional coupled biogeochemical model to investigate the relationship between eddies and the nitrogen-loss. We also investigate the mechanisms responsible for the generation of eddies and for possible modulations of eddy activity on interannual timescales, in particular during cold and warm phases of the El Nino Southern Oscillation.
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[Telemetry in the clinical setting].
Hilbel, Thomas; Helms, Thomas M; Mikus, Gerd; Katus, Hugo A; Zugck, Christian
2008-09-01
Telemetric cardiac monitoring was invented in 1949 by Norman J Holter. Its clinical use started in the early 1960s. In the hospital, biotelemetry allows early mobilization of patients with cardiovascular risk and addresses the need for arrhythmia or oxygen saturation monitoring. Nowadays telemetry either uses vendor-specific UHF band broadcasting or the digital ISM band (Industrial, Scientific, and Medical Band) standardized Wi-Fi network technology. Modern telemetry radio transmitters can measure and send multiple physiological parameters like multi-channel ECG, NIPB and oxygen saturation. The continuous measurement of oxygen saturation is mandatory for the remote monitoring of patients with cardiac pacemakers. Real 12-lead ECG systems with diagnostic quality are an advantage for monitoring patients with chest pain syndromes or in drug testing wards. Modern systems are light-weight and deliver a maximum of carrying comfort due to optimized cable design. Important for the system selection is a sophisticated detection algorithm with a maximum reduction of artifacts. Home-monitoring of implantable cardiac devices with telemetric functionalities are becoming popular because it allows remote diagnosis of proper device functionality and also optimization of the device settings. Continuous real-time monitoring at home for patients with chronic disease may be possible in the future using Digital Video Broadcasting Terrestrial (DVB-T) technology in Europe, but is currently not yet available.
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Wang, Steven; Giannakopoulos, Helen; Lowstetter, Jamie; Kaye, Laura; Lee, Catherine; Secreto, Stacey; Ho, Vanessa; Hutcheson, Matthew C; Farrar, John T; Wang, Ping; Doyle, Geraldine; Cooper, Stephen A; Hersh, Elliot V
2017-10-01
This study evaluated changes in methemoglobin and oxygen saturation concentrations after the administration of recommended doses of 14% benzocaine alone or 14% benzocaine combined with 2% tetracaine. American Society of Anesthesiology class 1 and 2 subjects (n = 40) were enrolled in this modified crossover study. Subjects were administered 0.2 mL of 14% benzocaine alone, 0.2 mL of 14% benzocaine plus 2% tetracaine, or 0.4 mL of 14% benzocaine plus 0.2% benzocaine to their cheek mucosa. Venous blood (5 mL) was drawn from the antecubital fossa before and 60 minutes after drug application for methemoglobin analyses. Oxygen saturation was also recorded via pulse oximetry at baseline and every 10 minutes through 60 minutes after drug application. Methemoglobin and oxygen saturation levels did not change from baseline after the administration of benzocaine alone or when combined with tetracaine. Recommended doses of benzocaine or benzocaine combined with tetracaine when applied to the cheek mucosa do not induce even clinically insignificant elevations in methemoglobin levels. Metered dosing, such as that used in this study, can help avoid this overdose phenomena with these drugs. ClinicalTrials.gov identifier: NCT02908620. Copyright © 2017 Elsevier HS Journals, Inc. All rights reserved.
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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.
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Evaluation of efficacy of a pulse oximeter to assess pulp vitality.
Sadique, Mohammed; Ravi, S V; Thomas, Kunjamma; Dhanapal, Prasanth; Simon, Elsy P; Shaheen, Mohammed
2014-06-01
To evaluate the efficacy of pulse oximeter as a pulp vitality tester. The sample group consisted of 60 patients of age 15 to 30 years with normal maxillary anterior teeth. Thirty nonvital teeth with complete endodontic fillings were tested as control group. Systemic oxygen saturation values from the patient's fingers served as the control sample for comparison of pulp oxygen saturation values. Readings were recorded on index fingers first; teeth were then evaluated by placing sensor onto the tooth. Nonvital teeth recorded oxygen saturation values of 0%. The mean value for central incisor was 85.11 (SD ± 2.07), for lateral incisors 80.21 (SD ± 2.03) and for canines 89.55 (SD ± 1.09). Their control values (patient's index fingers) averaged 95.88% (SD ± 0.66). Pearson's correlation analysis showed a correlation of 0.11 for central incisors, 0.19 for lateral incisors and 0.12 for canines. This study confirms that pulse oximeter is effective equipment for pulp vitality testing. Pulse oximeter evidences the actual method of evaluating the pulp vitality compared to contemporary methods. How to cite the article: Sadique M, Ravi SV, Thomas K, Dhanapal P, Simon EP, Shaheen M. Evaluation of efficacy of a pulse oximeter to assess pulp vitality. J Int Oral Health 2014;6(3):70-2.
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Dutra, Rosane Menezes Faria; Neves, Itamara Lucia Itagiba; Neves, Ricardo Simões; Atik, Edmar; de Paula Santos, Ubiratan
2014-01-01
OBJECTIVES: In this observational study, we evaluated the peripheral oxygen saturation (SpO2), heart rate, and blood pressure of children with cyanotic congenital heart disease who were undergoing dental extraction. METHODS: Forty-four patients between the ages of 6 and 12 years who underwent upper primary tooth extraction were included in the study. Of these, 20 patients were in the cyanotic congenital heart disease group and 24 were in the control group. RESULTS: Peripheral oxygen saturation, heart rate, and systolic blood pressure in the cyanotic congenital heart disease group varied quite significantly during the treatment protocol (p<0.05), with values of 80.5% (±7.6) to 82.8% (±7.8), 95.3 beats per minute (bpm) (±11.3) to 101.3 bpm (±9.8), and 93.6 mm Hg (±13,3) to 103.8 mm Hg (±12.7), respectively. The variations in the control group during the procedure were also significant. CONCLUSIONS: The changes observed during the study protocol, although statistically significant, were mild and lacked clinical relevance. The results indicate that dental treatment of children with cyanotic heart disease using a standardized protocol in decentralized offices without the support of a surgical center is safe. PMID:24838895
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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.
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Regulation of nitrite transport in red blood cells by hemoglobin oxygen fractional saturation.
Vitturi, Dario A; Teng, Xinjun; Toledo, José C; Matalon, Sadis; Lancaster, Jack R; Patel, Rakesh P
2009-05-01
Allosteric regulation of nitrite reduction by deoxyhemoglobin has been proposed to mediate nitric oxide (NO) formation during hypoxia. Nitrite is predominantly an anion at physiological pH, raising questions about the mechanism by which it enters the red blood cell (RBC) and whether this is regulated and coupled to deoxyhemoglobin-mediated reduction. We tested the hypothesis that nitrite transport by RBCs is regulated by fractional saturation. Using human RBCs, nitrite consumption was faster at lower fractional saturations, consistent with faster reactions with deoxyheme. A membrane-based regulation was suggested by slower nitrite consumption with intact versus lysed RBCs. Interestingly, upon nitrite addition, intracellular nitrite concentrations attained a steady state that, despite increased rates of consumption, did not change with decreasing oxygen tensions, suggesting a deoxygenation-sensitive step that either increases nitrite import or decreases the rate of nitrite export. A role for anion exchanger (AE)-1 in the control of nitrite export was suggested by increased intracellular nitrite concentrations in RBCs treated with DIDS. Moreover, deoxygenation decreased steady-state levels of intracellular nitrite in AE-1-inhibited RBCs. Based on these data, we propose a model in which deoxyhemoglobin binding to AE-1 inhibits nitrite export under low oxygen tensions allowing for the coupling between deoxygenation and nitrite reduction to NO along the arterial-to-venous gradient.
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Pacifier and swaddling effective in impeding premature infant's pain score and heart rate.
Efendi, Defi; Rustina, Yeni; Gayatri, Dewi
2018-02-01
To assess the effectiveness of pacifier and swaddling on premature infant's pain score, hearthrate, and oxygen saturation during an invasive procedure. This randomized control trial involv 30 premature infants who were randomly assigned into control (n=15) and intervention (n=15) groups using parallel design. Infants in the intervention group received pacifier and swaddling when they were undergoing invasive procedures. The outcome indicators of the two-day intervention were pain score, hearth rate, and oxygen saturation. The Premature Infant Pain Profile (PIPP) was used in this study to measure infants' pain. The paired t-test results showed that the pain score and heart rate were significantly increased following the procedure in the control group (p=0.003; p=0.013 < 0.05); meanwhile, there was no significant increase in the intervention group (p=0.256; p=0.783 > 0.005). There was no significant different in oxygen saturation in the control group (p=0.270) and in the intervention (p=0.370) group before and after the procedure. Providing pacifier and swaddling can impede the increase of premature infants' pain score and hearth rate during an invasive procedures, therefore it can be implemented as an alternative to pain management in premature infants. Copyright © 2018 Elsevier España, S.L.U. All rights reserved.
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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.
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Live maternal speech and singing have beneficial effects on hospitalized preterm infants.
Filippa, Manuela; Devouche, Emmanuel; Arioni, Cesare; Imberty, Michel; Gratier, Maya
2013-10-01
To study the effects of live maternal speaking and singing on physiological parameters of preterm infants in the NICU and to test the hypothesis that vocal stimulation can have differential effects on preterm infants at a behavioural level. Eighteen mothers spoke and sang to their medically stable preterm infants in their incubators over 6 days, between 1 and 2 pm. Heart rate (HR), oxygen saturation (OxSat), number of critical events (hypoxemia, bradycardia and apnoea) and change in behavioural state were measured. Comparisons of periods with and without maternal vocal stimulation revealed significantly greater oxygen saturation level and heart rate and significantly fewer negative critical events (p < 0.0001) when the mother was speaking and singing. Unexpected findings were the comparable effects of maternal talk and singing on infant physiological parameters and the differential ones on infant behavioural state. A renewed connection to the mother's voice can be an important and significant experience for preterm infants. Exposure to maternal speech and singing shows significant early beneficial effects on physiological state, such as oxygen saturation levels, number of critical events and prevalence of calm alert state. These findings have implications for NICU interventions, encouraging maternal interaction with their medically stable preterm infants. ©2013 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.
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Nobile, Stefano; Gnocchini, Francesco; Pantanetti, Marco; Battistini, Paola; Carnielli, Virgilio P
2014-01-01
To report the impact of the adoption of a low oxygen saturation policy on retinopathy of prematurity (ROP) incidence at a single tertiary care center. ROP incidence, procedures for ROP, and neonatal outcome among very low birth weight infants were compared before and after the adoption of a low saturation policy, which took place in 2004. The Mann– Whitney test was performed to look for differences. The incidence of severe ROP significantly decreased from 5.3% of live very low birth weight infants between 1999 and 2004 to 1% of live very low birth weight infants between 2005 and 2012 (P = .003). The use of laser therapy for severe ROP between the same periods significantly decreased from 6.4% of live very low birth weight infants between 1999 and 2004 to 0.6% of live very low birth weight infants between 2005 and 2012 (P = .002). There was also a significant reduction of death or bronchopulmonary dysplasia from 33.8% between 1999 and 2004 to 24.2% between 2005 and 2012 (P = .02). Trained personnel and low and tailored oxygen saturation intervals for very low birth weight infants could play a pivotal role in reducing the incidence of severe ROP without increasing mortality.
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NASA Astrophysics Data System (ADS)
Fathi, H.; Raoof, A.; Mansouri, S. H.
2017-05-01
The production of liquid water in cathode catalyst layer, CCL, is a significant barrier to increase the efficiency of proton exchange membrane fuel cell. Here we present, for the first time, a direct three-dimensional pore-scale modelling to look at the complex immiscible two-phase flow in CCL. After production of the liquid water at the surface of CCL agglomerates due to the electrochemical reactions, water spatial distribution affects transport of oxygen through the CCL as well as the rate of reaction at the agglomerate surfaces. To explore the wettability effects, we apply hydrophilic and hydrophobic properties using different surface contact angles. Effective diffusivity is calculated under several water saturation levels. Results indicate larger diffusive transport values for hydrophilic domain compared to the hydrophobic media where the liquid water preferentially floods the larger pores. However, hydrophobic domain showed more available surface area and higher oxygen consumption rate at the reaction sites under various saturation levels, which is explained by the effect of wettability on pore-scale distribution of water. Hydrophobic domain, with a contact angle of 150, reveals efficient water removal where only 28% of the pore space stays saturated. This condition contributes to the enhanced available reaction surface area and oxygen diffusivity.
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Collier, Anderson B; Coon, Lea M; Monteleone, Philip; Umaru, Samuel; Swanson, Kenneth C; Hoyer, James D; Oliveira, Jennifer L
2016-01-01
Hemoglobin (Hb) variants may be associated with low oxygen saturation and exacerbated episodes of anemia from common stressors such as viral infections. These attributes frequently cause increased clinical concern and unnecessary and expensive testing if not considered early in the evaluation of the patient. Some clinically significant Hb variants result in a normal Hb electrophoresis result, which can be method-dependent. Herein we describe a patient with low oxygen saturation and a history of hemolytic anemia who was subsequently found to carry a novel, unstable β-globin variant that we have named Hb Allentown [β137(H15)Val→Trp (GTG>TGG) HBB: c.412_413delinsTG, p.Val138Trp] for the place of identification of the variant. Hb Allentown is formed by a rare double nucleotide substitution within the same codon. Additionally, positive identification of rare Hb variants characterized by a single method is discouraged, as the Hb variant was misclassified as Hb S-South End or β6(A3)Glu→Val;β132(H10)Lys→Asn (HBB: c.[20A > T;399A > C]) by the initial laboratory.