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Sample records for measure cardiac output

  1. Cardiac output measurement in pediatric anesthesia.

    PubMed

    Skowno, Justin J; Broadhead, Michael

    2008-11-01

    Maintenance of cardiovascular stability is crucial to safe anesthetic practice, but measurement of cardiac output has been technically challenging, particularly in pediatric patients. Cardiovascular monitoring has therefore generally relied upon pressure-based measurements, as opposed to flow-based measurements. The measurement of cardiac output under anesthesia and in critical care has recently become easier as a result of new techniques of measurement. This article reviews the basic concepts of and rationale for cardiac output monitoring, and then describes the techniques available for monitoring in clinical practice.

  2. Methods in pharmacology: measurement of cardiac output

    PubMed Central

    Geerts, Bart F; Aarts, Leon P; Jansen, Jos R

    2011-01-01

    Many methods of cardiac output measurement have been developed, but the number of methods useful for human pharmacological studies is limited. The ‘holy grail’ for the measurement of cardiac output would be a method that is accurate, precise, operator independent, fast responding, non-invasive, continuous, easy to use, cheap and safe. This method does not exist today. In this review on cardiac output methods used in pharmacology, the Fick principle, indicator dilution techniques, arterial pulse contour analysis, ultrasound and bio-impedance are reviewed. PMID:21284692

  3. Automated cardiac output measurements by ultrasound are inaccurate at high cardiac outputs.

    PubMed

    Basdogan, F; Visser, W; Struijk, P C; Jansen, J R; Vletter, W B; Wladimiroff, J W; Lotgering, F K

    2000-06-01

    The sonographic technique of automated cardiac output measurement (ACM) is a promising new method to measure cardiac output and could be of use in a high-risk obstetric unit in the treatment of pre-eclamptic patients. The aim was to determine the accuracy of the ACM method. Comparative study of the sonographic technique of ACM versus cardiac output measured by thermodilution (TD). The study included 39 intensive care patients, 21 men, 13 non-pregnant women and five severely pre-eclamptic pregnant patients, with a wide range of cardiac outputs, in whom TD catheters had been inserted for clinical reasons. Two separate experienced observers, blinded to the results obtained with the other method, performed four successive measurements in each patient with either the ACM or TD technique. The averaged cardiac output value per patient and method was used for comparison. Cardiac output was successfully measured with ACM and TD in 85 and 100% of patients, respectively. Mean cardiac output measured by ACM (6.77 +/- 1.90 L/min) was significantly lower than that measured by TD (9.12 +/- 3.06 L/min). Although cardiac output values obtained with ACM were significantly correlated with those measured by TD, the ACM values were consistently lower than TD values in the higher cardiac output range; the relationship was represented by ACM = 0.35 TD + 3.55 L/min (r = 0.57, P < 0.001). The (ACM - TD) difference increased significantly with cardiac output, through a difference in stroke volume, not in heart rate. The ACM is not an accurate tool to measure cardiac output in patients with a high cardiac output, including treated pre-eclamptic women.

  4. Videodensitometric Methods for Cardiac Output Measurements

    NASA Astrophysics Data System (ADS)

    Mischi, Massimo; Kalker, Ton; Korsten, Erik

    2003-12-01

    Cardiac output is often measured by indicator dilution techniques, usually based on dye or cold saline injections. Developments of more stable ultrasound contrast agents (UCA) are leading to new noninvasive indicator dilution methods. However, several problems concerning the interpretation of dilution curves as detected by ultrasound transducers have arisen. This paper presents a method for blood flow measurements based on UCA dilution. Dilution curves are determined by real-time densitometric analysis of the video output of an ultrasound scanner and are automatically fitted by the Local Density Random Walk model. A new fitting algorithm based on multiple linear regression is developed. Calibration, that is, the relation between videodensity and UCA concentration, is modelled by in vitro experimentation. The flow measurement system is validated by in vitro perfusion of SonoVue contrast agent. The results show an accurate dilution curve fit and flow estimation with determination coefficient larger than 0.95 and 0.99, respectively.

  5. Evaluation of hemodynamic measurements, including lithium dilution cardiac output, in anesthetized dogs undergoing ovariohysterectomy.

    PubMed

    Miyake, Yukari; Wagner, Ann E; Hellyer, Peter W

    2005-11-01

    To measure cardiac output in healthy female anesthetized dogs by use of lithium dilution cardiac output and determine whether changes in mean arterial pressure were caused by changes in cardiac output or systemic vascular resistance. Prospective clinical study. 20 healthy female dogs. Dogs were anesthetized for ovariohysterectomy. Ten dogs breathed spontaneously throughout anesthesia, and 10 dogs received intermittent positive-pressure ventilation. Cardiovascular and respiratory measurements, including lithium dilution cardiac output, were performed during anesthesia and surgery. Mean arterial pressure and systemic vascular resistance index were low after induction of anesthesia and just prior to surgery and increased significantly after surgery began. Cardiac index (cardiac output indexed to body surface area) did not change significantly throughout anesthesia and surgery. Results provide baseline data for cardiac output and cardiac index measurements during clinical anesthesia and surgery in dogs. Changes in mean arterial pressure do not necessarily reflect corresponding changes in cardiac index.

  6. A computerised dichromatic earpiece densitometer for the measurement of cardiac output.

    PubMed

    Robinson, P S; Crowther, A; Jenkins, B S; Webb-Peploe, M M; Coltart, D J

    1979-07-01

    This study assesses a precalibrated dichromatic earpiece densitometer and microprocessor for the measurement of cardiac output by indocyanine green dye dilution. The measured cardiac output is compared with values of cardiac output simultaneously determined using a cuvette densitometer. The microprocessor computation of cardiac output agreed very closely with the cardiac output determined by manual calculation from the same dye dilution curves (standard deviation +/- 1.47%). The reproducibility of the earpiece densitometer (standard deviation +/- 5.2%) was virtually identical to that of the cuvette densitometer (+/- 5.3%). In a comparison of earpiece and cuvette densitometers for 60 measurements of cardiac output following pulmonary arterial injection of dye and for 50 measurements following femoral venous injection of dye, correlation coefficients were 0.83 and 0.78 and the standard deviations of the differences of simultaneous measurements were 7.2% and 8.3% respectively. The instrument offers an accurate reproducible and relatively noninvasive technique for measuring cardiac output.

  7. Fiberoptic ear densitometer for measurement of cardiac output.

    PubMed

    Sekelj, P; Retfalvi, S; Lavoie, A

    1978-02-01

    This study presents theory, operation, and evaluation of a new earpiece method for measurement of cardiac output using the multichannel fiberoptic system recently described. The system includes an earpiece of simple design and small size suitable for applications in all subjects regardless of their age or size. The method requires no withdrawal and analysis of blood samples for calibration. Compared with earlier techniques the present method, based on measurements in three distinct absorption bands in the infrared, provides an increase in accuracy of the estimations. This accuracy was tested in children undergoing routine cardiac catheterization. Comparisons were made in 39 instances (25 subjects) between simultaneously carried out determinations by the earpiece and cuvette densitometer methods. The agreement was good (r = 0.97, p less than 0.001), with a standard deviation of the differences of 0.479 litre/min, or 10.2% of the mean values derived from the cuvette curves. The regression equation describing the values derived from ear curves in terms of values from the cuvette curves differed only slightly from unity (Y = 0.167 + 0.985X). The usefulness of the fiberoptic earpiece technique both in clinical investigations and cardiovascular diagnosis was demonstrated.

  8. Measurement of cardiac output from dynamic pulmonary circulation time CT

    SciTech Connect

    Yee, Seonghwan; Scalzetti, Ernest M.

    2014-06-15

    Purpose: To introduce a method of estimating cardiac output from the dynamic pulmonary circulation time CT that is primarily used to determine the optimal time window of CT pulmonary angiography (CTPA). Methods: Dynamic pulmonary circulation time CT series, acquired for eight patients, were retrospectively analyzed. The dynamic CT series was acquired, prior to the main CTPA, in cine mode (1 frame/s) for a single slice at the level of the main pulmonary artery covering the cross sections of ascending aorta (AA) and descending aorta (DA) during the infusion of iodinated contrast. The time series of contrast changes obtained for DA, which is the downstream of AA, was assumed to be related to the time series for AA by the convolution with a delay function. The delay time constant in the delay function, representing the average time interval between the cross sections of AA and DA, was determined by least square error fitting between the convoluted AA time series and the DA time series. The cardiac output was then calculated by dividing the volume of the aortic arch between the cross sections of AA and DA (estimated from the single slice CT image) by the average time interval, and multiplying the result by a correction factor. Results: The mean cardiac output value for the six patients was 5.11 (l/min) (with a standard deviation of 1.57 l/min), which is in good agreement with the literature value; the data for the other two patients were too noisy for processing. Conclusions: The dynamic single-slice pulmonary circulation time CT series also can be used to estimate cardiac output.

  9. Doppler echocardiographic measurement of cardiac output using the mitral orifice method.

    PubMed Central

    Zhang, Y; Nitter-Hauge, S; Ihlen, H; Myhre, E

    1985-01-01

    Cardiac output was determined in 20 patients with various cardiac conditions by measuring the cross sectional area of the mitral orifice by echocardiography and the transmitral flow by the Doppler technique. Cardiac output was calculated by multiplying the corrected mitral orifice area by the maximum diastolic velocity integral recorded by the pulsed mode. The results were compared with that obtained by the Fick method. The correlation for cardiac output by the two techniques was high in the whole group, particularly in patients without mitral regurgitation. There was also a good correlation for stroke volume determined by the two methods. Cardiac output was significantly overestimated by the continuous mode and in patients with mitral regurgitation. These results show that the mitral orifice method provides a new and reliable approach to the non-invasive measurement of cardiac output. Images PMID:3966956

  10. Comparison of the ability of two continuous cardiac output monitors to measure trends in cardiac output: estimated continuous cardiac output measured by modified pulse wave transit time and an arterial pulse contour-based cardiac output device.

    PubMed

    Terada, Takashi; Oiwa, Ayano; Maemura, Yumi; Robert, Samuna; Kessoku, Sayaka; Ochiai, Ryoichi

    2016-10-01

    Estimated continuous cardiac output (esCCO), a noninvasive technique for continuously measuring cardiac output (CO), is based on modified pulse wave transit time, which in turn is determined by pulse oximetry and electrocardiography. However, its trending ability has never been evaluated in patients undergoing non-cardiac surgery. Therefore, this study examined esCCO's ability to detect the exact changes in CO, compared with currently available arterial waveform analysis methods, in patients undergoing kidney transplantation. CO was measured using an esCCO system and arterial pressure-based CO (APCO), and compared with a corresponding intermittent bolus thermodilution CO (ICO) method. Percentage error and statistical methods, including concordance analysis and polar plot analysis, were used to analyze results from 15 adult patients. The difference in the CO values between esCCO and ICO was -0.39 ± 1.15 L min(-1) (percentage error, 35.6 %). And corrected precision for repeated measures was 1.16 L min(-1) (percentage error for repeated measures, 36.0 %). A concordance analysis showed that the concordance rate was 93.1 %. The mean angular bias was -1.8° and the radial limits of agreement were ±37.6°. The difference between the APCO and ICO CO values was 0.04 ± 1.37 L min(-1) (percentage error, 42.4 %). And corrected precision for repeated measures was 1.37 L min(-1) (percentage error for repeated measures, 42.5 %). The concordance rate was 89.7 %, with a mean angular bias of -3.3° and radial limits of agreement of ±42.2°. This study demonstrated that the trending ability of the esCCO system is not clinically acceptable, as judged by polar plots analysis; however, its trending ability is clinically acceptable based on a concordance analysis, and is comparable with currently available arterial waveform analysis methods.

  11. Validation of a continuous, arterial pressure-based cardiac output measurement: a multicenter, prospective clinical trial.

    PubMed

    McGee, William T; Horswell, Jeffrey L; Calderon, Joachim; Janvier, Gerard; Van Severen, Tom; Van den Berghe, Greet; Kozikowski, Lori

    2007-01-01

    The present study compared measurements of cardiac output by an arterial pressure-based cardiac output (APCO) analysis method with measurement by intermittent thermodilution cardiac output (ICO) via pulmonary artery catheter in a clinical setting. The multicenter, prospective clinical investigation enrolled patients with a clinical indication for cardiac output monitoring requiring pulmonary artery and radial artery catheters at two hospitals in the United States, one hospital in France, and one hospital in Belgium. In 84 patients (69 surgical patients), the cardiac output was measured by analysis of the arterial pulse using APCO and was measured via pulmonary artery catheter by ICO; to establish a reference comparison, the cardiac output was measured by continuous cardiac output (CCO). Data were collected continuously by the APCO and CCO technologies, and at least every 4 hours by ICO. No clinical interventions were made as part of the study. For APCO compared with ICO, the bias was 0.20 l/min, the precision was +/- 1.28 l/min, and the limits of agreement were -2.36 l/m to 2.75 l/m. For CCO compared with ICO, the bias was 0.66 l/min, the precision was +/- 1.05 l/min, and the limits of agreement were -1.43 l/m to 2.76 l/m. The ability of APCO and CCO to assess changes in cardiac output was compared with that of ICO. In 96% of comparisons, APCO tracked the change in cardiac output in the same direction as ICO. The magnitude of change was comparable 59% of the time. For CCO, 95% of comparisons were in the same direction, with 58% of those changes being of similar magnitude. In critically ill patients in the intensive care unit, continuous measurement of cardiac output using either APCO or CCO is comparable with ICO. Further study in more homogeneous populations may refine specific situations where APCO reliability is strongest.

  12. Measurement of cardiac output in adult and newborn animals by ascorbic acid dilution.

    PubMed

    Smallwood, J K; Haselby, K A; Paradise, R R

    1984-05-01

    We have developed an ascorbic acid-dilution method for measuring cardiac output which requires minimal blood withdrawal. Ascorbate is injected into a central venous catheter. The indicator-dilution curve is obtained by drawing blood from an arterial catheter through an amperometric cell at 0.96 ml/min for 35 s. The current is measured by a picoammeter . A calibration curve is obtained in 15 s prior to each indicator-dilution curve. An on-line digital computer measures the curve areas and calculates the cardiac output. Cardiac outputs of heparinized dogs anesthetized with pentobarbital and halothane measured by this method (AA) compared closely to cardiac outputs measured by the dye-dilution method (CG) (AA = 0.96 CG + 20 ml/min, r = 0.98). Both the cardiac output and the arterial blood pressure remained stable during replicate measurements of the cardiac output of 1-day-old piglets. This system allows cardiac output determinations of neonatal subjects without excessive blood removal and, with further development, should be practical in human neonates.

  13. Continuous cardiac output measurement - Aspects of Doppler frequency analysis

    NASA Technical Reports Server (NTRS)

    Mackay, R. S.; Hechtman, H. B.

    1975-01-01

    From the suprasternal notch blood flow velocity in the aorta can be measured non-invasively by a Doppler probe. Integration over systole after frequency analysis gives a measure of stroke volume if a separate diameter observation is incorporated. Frequency analysis by a zero crossing counter or by a set of parallel phaselock loops was less effective than a set of bandpass filters. Observations on dogs, baboons and humans before and after exercise or surgery suggest the indications to be useful. Application to judging heart failure by the effect of introducing a volume load is indicated. Changes in output also are measured in freely moving subjects.

  14. Continuous cardiac output measurement - Aspects of Doppler frequency analysis

    NASA Technical Reports Server (NTRS)

    Mackay, R. S.; Hechtman, H. B.

    1975-01-01

    From the suprasternal notch blood flow velocity in the aorta can be measured non-invasively by a Doppler probe. Integration over systole after frequency analysis gives a measure of stroke volume if a separate diameter observation is incorporated. Frequency analysis by a zero crossing counter or by a set of parallel phaselock loops was less effective than a set of bandpass filters. Observations on dogs, baboons and humans before and after exercise or surgery suggest the indications to be useful. Application to judging heart failure by the effect of introducing a volume load is indicated. Changes in output also are measured in freely moving subjects.

  15. Iterative cardiac output measurement for optimizing cardiac resynchronization therapy: a randomized, blinded, crossover study.

    PubMed

    Reinsch, Nico; Konorza, Thomas; Woydowski, Dagmar; Bruck, Heike; Volsek, Michaela; Müller-Tasch, Thomas; Neumann, Till; Erbel, Raimund; Wieneke, Heinrich

    2010-10-01

    Many invasive and noninvasive methods have been proposed for guiding optimal programming of cardiac resynchronization therapy (CRT) devices. However, results are not satisfying. Preliminary results suggest that cardiac output (CO) measurements using inert gas rebreathing (IGR) might be an eligible method to tailor atrioventricular (AV) and ventriculo-ventricular (VV) programming. The aims of the present study were: (1) to evaluate whether an optimization of CRT can be obtained by noninvasive CO measurements and (2) to evaluate whether acute hemodynamic improvements obtained by this approach relate into increase in cardiac exercise capacity. In 24 patients on CRT, iterative VV- and AV-delay optimization was done using the IGR method. This blinded, randomized, crossover study compared the responses to optimization during two periods: a 4-week optimized and a 4-week standard programming. Exercise capacity after optimization was assessed after each period by New York Heart Association (NYHA) classification, a 6-minute walking test, and quality of life (QoL) questionnaire. CO could be determined by IGR in all patients. The NYHA class decreased by 17.8% (2.8 ± 0.3 vs 2.3 ± 0.4, P < 0.001), the mean (± standard deviation) distance walked in 6 minutes was 9.3% greater after optimization (456 ± 140 m vs 417 ± 134 m, P < 0.001), and the QoL improved by 14.5% (41.8 ± 10.4 vs 36.5 ± 9.5, P < 0.001). The portion of responders to CRT increased from 66.5% to 87.5%. CRT optimization by iterative CO measurements leads to an increase in CO and an improvement of exercise capacity. Our results suggest that this method might become an important additive tool to adjust CRT programming. ©2010, The Authors. Journal compilation ©2010 Wiley Periodicals, Inc.

  16. Correlation of carotid blood flow and corrected carotid flow time with invasive cardiac output measurements.

    PubMed

    Ma, Irene W Y; Caplin, Joshua D; Azad, Aftab; Wilson, Christina; Fifer, Michael A; Bagchi, Aranya; Liteplo, Andrew S; Noble, Vicki E

    2017-12-01

    Non-invasive measures that can accurately estimate cardiac output may help identify volume-responsive patients. This study seeks to compare two non-invasive measures (corrected carotid flow time and carotid blood flow) and their correlations with invasive reference measurements of cardiac output. Consenting adult patients (n = 51) at Massachusetts General Hospital cardiac catheterization laboratory undergoing right heart catheterization between February and April 2016 were included. Carotid ultrasound images were obtained concurrently with cardiac output measurements, obtained by the thermodilution method in the absence of severe tricuspid regurgitation and by the Fick oxygen method otherwise. Corrected carotid flow time was calculated as systole time/√cycle time. Carotid blood flow was calculated as π × (carotid diameter)(2)/4 × velocity time integral × heart rate. Measurements were obtained using a single carotid waveform and an average of three carotid waveforms for both measures. Single waveform measurements of corrected flow time did not correlate with cardiac output (ρ = 0.25, 95% CI -0.03 to 0.49, p = 0.08), but an average of three waveforms correlated significantly, although weakly (ρ = 0.29, 95% CI 0.02-0.53, p = 0.046). Carotid blood flow measurements correlated moderately with cardiac output regardless of if single waveform or an average of three waveforms were used: ρ = 0.44, 95% CI 0.18-0.63, p = 0.004, and ρ = 0.41, 95% CI 0.16-0.62, p = 0.004, respectively. Carotid blood flow may be a better marker of cardiac output and less subject to measurements issues than corrected carotid flow time.

  17. Comparison of impedance cardiography and dye dilution method for measuring cardiac output

    PubMed Central

    Spiering, W; van Es, P N; de Leeuw, P W

    1998-01-01

    Objective—To assess the degree of agreement between impedance cardiography, using the NCCOM3-R7 device, and the gold standard—the dye dilution method—both under basal conditions and after stimulation of cardiac output.
Patients—35 paired measurements in five healthy male volunteers.
Interventions—To obtain higher levels of cardiac output, cardiac performance was stimulated with a dopamine infusion.
Results—In 35 paired measurements, the mean of all the impedance values was higher than that of the dye dilution values, at 10.2 v 7.4 l/min (p < 0.0001). The mean discrepancy between the two methods was 3.3 l/min, and the mean bias −2.9 l/min, with limits of agreement of −9.0 and 3.2 l/min. A change in cardiac output could not adequately be predicted by the NCCOM3-R7. In 20 of 25 measurements obtained during continuous intravenous dopamine infusions there was a rise in dye dilution cardiac output (range 0.2 to 5.9 l/min). Neither the magnitude nor the direction of the change in dye dilution values corresponded with the change measured by impedance cardiography. The mean discrepancy here between the two methods was 1.8 l/min, and the mean bias −0.8 l/min, with limits of agreement of −4.9 and 3.3 l/min.
Conclusions—In healthy volunteers, impedance cardiography with NCCOM3-R7 is inadequate for assessing cardiac output when compared with the dye dilution method.

 Keywords: cardiac output;  impedance cardiography;  dye dilution PMID:9659188

  18. Evaluation of transpulmonary thermodilution as a method to measure cardiac output in anesthetized cats.

    PubMed

    Beaulieu, Kim E; Kerr, Carolyn L; McDonell, Wayne N

    2009-01-01

    The objectives of this study were to evaluate the use of a transpulmonary thermodilution (Trans) technique for the measurement of cardiac output, and to determine the agreement between Trans and conventional thermodilution (TD) in anesthetized cats. Using each technique, cardiac output was measured in 5 mature cats (weights 2.4 to 5.6 kg) anesthetized with isoflurane. To induce different levels of cardiac output in each cat, anesthesia was maintained at > 1.5x end-tidal minimum alveolar concentration (MAC) of isoflurane, and at 1.3x end-tidal isoflurane MAC with and without administration of dobutamine. At least 2 comparisons between TD and Trans values were made at each cardiac output rate. Thirty-two of the 42 recorded comparisons were analyzed. Linear regression analysis (TD vs Trans) yielded an r(2) value of 0.83. The mean bias (TD-Trans) was -3.7 mL/kg/min with limits of agreement of -35.9 to 28.5 mL/kg/min. The concordance coefficient was 0.91. The Trans method showed good relationship and good agreement with TD in anesthetized cats. The Trans method is a relatively noninvasive, practical, and safe method to measure cardiac output in anesthetized cats.

  19. Noninvasive measurement of cardiac output during exercise by inert gas rebreathing technique.

    PubMed

    Cattadori, Gaia; Schmid, Jean-Paul; Agostoni, Piergiuseppe

    2009-04-01

    Reduced exercise tolerance and dyspnea during exercise are hallmarks of heart failure syndrome. Exercise capacity and various parameters of cardiopulmonary response to exercise are of important prognostic value. All the available parameters only indirectly reflect left ventricular dysfunction and hemodynamic adaptation to an increased demand. Noninvasive assessment of cardiac output, especially during an incremental exercise stress test, would allow the direct measure of cardiac reserve and may become the gold standard for prognostic evaluation in the future.

  20. Validation of a new spectrometer for noninvasive measurement of cardiac output

    NASA Astrophysics Data System (ADS)

    Baum, Marc M.; Kumar, Sasi; Moss, John A.; Wagner, Peter D.

    2004-07-01

    Acetylene is a blood-soluble gas and for many years its uptake rate during rebreathing tests has been used to calculate the flow rate of blood through the lungs (normally equal to cardiac output) as well as the volume of lung tissue. A new, portable, noninvasive instrument for cardiac output determination using the acetylene uptake method is described. The analyzer relies on nondispersive IR absorption spectroscopy as its principle of operation and is configured for extractive (side-stream) sampling. The instrument affords exceptionally fast (30 ms, 10%-90%, 90%-10%, at 500 mL min-1 flow rates), interference-free, simultaneous measurement of acetylene, sulfur hexafluoride (an insoluble reference gas used in the cardiac output calculation), and carbon dioxide (to determine alveolar ventilation), with good (typically ±2% full-scale) signal-to-noise ratios. Comparison tests with a mass spectrometer using serially diluted calibration gas samples gave excellent (R2>0.99) correlation for all three gases, validating the IR system's linearity and accuracy. A similar level of agreement between the devices also was observed during human subject C2H2 uptake tests (at rest and under incremental levels of exercise), with the instruments sampling a common extracted gas stream. Cardiac output measurements by both instruments were statistically equivalent from rest to 90% of maximal oxygen consumption; the physiological validity of the measurements was confirmed by the expected linear relationship between cardiac output and oxygen consumption, with both the slope and intercept in the published range. These results indicate that the portable, low-cost, rugged prototype analyzer discussed here is suitable for measuring cardiac output noninvasively in a point-of-care setting.

  1. Measurement of cardiac output by earpiece dye-dilution method with automatic calibration of dye concentration.

    PubMed

    Katori, R; Hayashi, T; Kanamasa, K; Ishikawa, K

    1977-05-01

    A non-invasive method for measuring cardiac output by an earpiece dye densitometer was proposed. The densitometer is dichromatic and has an air capsule to make subject's ear bloodless by inflation, so that it can calibrate indocyanine green dye concentration without blood sampling. Duplicate measurements of cardiac output showed a good agreement in 40 cases (r = 0.97, standard deviation (S.D.) = 8.9%), which was comparable to the result of the cuvette method (r = 0.98, S.D. = 8.1%). Simultaneous measurements of cardiac output by the earpiece method (x) and the standard cuvette method (y) revealed a good agreement (r = 0.91, y = 0.96x+0.34, S.D. = 16.4%) in 52 measurements of 25 cases. A similarly good correlation was obtained between the two methods during ergometer exercise in supine position in 5 cases. These suggest that this earpiece dye-dilution method is reliable for cardiac output measurement and advantageous for clinical use because of non-invasive technique.

  2. Cardiac output after burn injury.

    PubMed Central

    Porter, J. M.; Shakespeare, P. G.

    1984-01-01

    Cardiac output after burn injury has been measured by the non-invasive method of impedance plethysmography. An initial study of 143 normal subjects was undertaken in order to investigate variations in cardiac output with age. Fifteen patients were monitored during resuscitation after extensive burns. Fourteen patients showed a depression of stroke volume below the lower limits of the normal range, derived from the initial study on normal people. PMID:6691694

  3. Cardiac output measurement in newborn infants using the ultrasonic cardiac output monitor: an assessment of agreement with conventional echocardiography, repeatability and new user experience.

    PubMed

    Patel, Neil; Dodsworth, Melissa; Mills, John F

    2011-05-01

    To assess (1) agreement between the ultrasonic cardiac output monitor (USCOM) 1A device for measurement of cardiac output in newborn infants and conventional echocardiography (ECHO), (2) repeatability of USCOM measurements and (3) agreement between novice and expert users of the USCOM. A prospective observational study. The Neonatal Unit at the Royal Children's Hospital, Melbourne, Australia. 56 term and near-term infants, with no evidence of structural or functional cardiovascular disease, or haemodynamic shunts. Agreement between ECHO and USCOM was assessed by paired measurements of ventricular outputs by a single experienced user. Repeatability was assessed using five repeated measurements in 10 infants. Agreement between five novices and one expert user was assessed by paired USCOM measurements over 30 training measurements. Agreement between USCOM and ECHO for left ventricular output (LVO) was (bias, ±limits of agreement, mean % error): 14, ±108 ml/kg/min, 43%, and for right ventricular output (RVO): -59, ±160, ml/kg/min, 57%. Intra-observer repeatability was 6.7% for USCOM LVO and 3.6% for ECHO LVO. After five training measurements, the mean difference between USCOM measures of LVO by novice and expert users was less than 50 ml/kg/min, but with variability. Repeatability of USCOM measures is high in newborn infants. New users can be trained quickly, but with high inter-user variability. Agreement between USCOM and conventional ECHO is broad, and worse for RVO and LVO. Further studies are required to assess the ability of the device to detect clinically significant changes in infant cardiac output.

  4. Mathematics and the Heart: Understanding Cardiac Output

    ERIC Educational Resources Information Center

    Champanerkar, Jyoti

    2013-01-01

    This paper illustrates a biological application of the concepts of relative change and area under a curve, from mathematics. We study two biological measures "relative change in cardiac output" and "cardiac output", which are predictors of heart blockages and other related ailments. Cardiac output refers to the quantity of…

  5. Mathematics and the Heart: Understanding Cardiac Output

    ERIC Educational Resources Information Center

    Champanerkar, Jyoti

    2013-01-01

    This paper illustrates a biological application of the concepts of relative change and area under a curve, from mathematics. We study two biological measures "relative change in cardiac output" and "cardiac output", which are predictors of heart blockages and other related ailments. Cardiac output refers to the quantity of…

  6. [Non-invasive cardiac output measurement with USCOM in air rescue operation].

    PubMed

    Schedler, O; Handschak, H; Hensel, M

    2008-12-01

    In cardiac emergency events (NACA score = 3.4), a non-invasive cardiac output test involving transaortalic blood flow velocity measurement was used in the air rescue of 30 patients. An average velocity integral (Vti) of 21.9 +/- 9.9 cm was determined in the short examination time (t = 120 +/- 30 sec). Related to the middle body surface (BSA = 2.0 +/- 0.3 m (2)), the calculated cardiac index (CI) was 2.6 +/- 1.1 l/min/m (2). The CI was under 2.2 l/min/m (2) in 12 examinations (40 %). 5 patients in this group subsequently received catecholamine therapy. Thrombolysis therapy increased by 17 % in the myocardial infarction group with CI measurement. However, the results do not justify a definitive recommendation for application of the USCOM system in air rescue service.

  7. Comparison Between Doppler-Echocardiography and Uncalibrated Pulse Contour Method for Cardiac Output Measurement: A Multicenter Observational Study.

    PubMed

    Scolletta, Sabino; Franchi, Federico; Romagnoli, Stefano; Carlà, Rossella; Donati, Abele; Fabbri, Lea P; Forfori, Francesco; Alonso-Iñigo, José M; Laviola, Silvia; Mangani, Valerio; Maj, Giulia; Martinelli, Giampaolo; Mirabella, Lucia; Morelli, Andrea; Persona, Paolo; Payen, Didier

    2016-07-01

    Echocardiography and pulse contour methods allow, respectively, noninvasive and less invasive cardiac output estimation. The aim of the present study was to compare Doppler echocardiography with the pulse contour method MostCare for cardiac output estimation in a large and nonselected critically ill population. A prospective multicenter observational comparison study. The study was conducted in 15 European medicosurgical ICUs. We assessed cardiac output in 400 patients in whom an echocardiographic evaluation was performed as a routine need or for cardiocirculatory assessment. None. One echocardiographic cardiac output measurement was compared with the corresponding MostCare cardiac output value per patient, considering different ICU admission categories and clinical conditions. For statistical analysis, we used Bland-Altman and linear regression analyses. To assess heterogeneity in results of individual centers, Cochran Q, and the I statistics were applied. A total of 400 paired echocardiographic cardiac output and MostCare cardiac output measures were compared. MostCare cardiac output values ranged from 1.95 to 9.90 L/min, and echocardiographic cardiac output ranged from 1.82 to 9.75 L/min. A significant correlation was found between echocardiographic cardiac output and MostCare cardiac output (r = 0.85; p < 0.0001). Among the different ICUs, the mean bias between echocardiographic cardiac output and MostCare cardiac output ranged from -0.40 to 0.45 L/min, and the percentage error ranged from 13.2% to 47.2%. Overall, the mean bias was -0.03 L/min, with 95% limits of agreement of -1.54 to 1.47 L/min and a relative percentage error of 30.1%. The percentage error was 24% in the sepsis category, 26% in the trauma category, 30% in the surgical category, and 33% in the medical admission category. The final overall percentage error was 27.3% with a 95% CI of 22.2-32.4%. Our results suggest that MostCare could be an alternative to echocardiography to assess

  8. The clinical application of pulse contour cardiac output and intrathoracic volume measurements in critically ill patients.

    PubMed

    Hewitt, Nicky A; Braaf, Sandra C

    2006-08-01

    Cardiac output (CO) determination by pulmonary artery (PA) catheter has increasingly been criticised within the literature due to its invasive nature and poor correlation between the pressure measurements and intravascular volume status in mechanically ventilated patients. Consequently, alternative less invasive technologies to PA catheterisation are emerging within intensive care. One such novel technology are pulse contour CO (PCCO) systems. They establish comprehensive and continuous haemodynamic monitoring utilising a central venous catheter (CVC) and an arterial line. Furthermore, a key feature of this technology is its ability to produce intrathoracic volume measurements which may provide a better estimation of cardiac preload as well as indicate the presence and severity of pulmonary oedema. This article aims to discuss the theoretical basis and clinical application of PCCO systems, how PCCO systems differ from PA catheters and how the intrathoracic volume measurements are derived. Understanding these advanced concepts will ensure that clinicians are able to employ this innovative monitoring technology more effectively.

  9. Electrical velocimetry for measuring cardiac output in children with congenital heart disease.

    PubMed

    Norozi, K; Beck, C; Osthaus, W A; Wille, I; Wessel, A; Bertram, H

    2008-01-01

    The purpose of this study was to evaluate the agreement of cardiac output measurements obtained by electrical velocimetry (CO(EV)) and those that derived from the direct Fick-oxygen principle (CO(F)) in infants and children with congenital heart defects. Simultaneous measurements of CO(EV) and CO(F) were compared in 32 paediatric patients, aged 11 days to 17.8 yr, undergoing diagnostic right and left heart catheterization. For non-invasive measurements of cardiac output by electrical velocimetry, which is a variation of impedance cardiography, standard surface electrodes were applied to the left side of the neck and the left side of the thorax at the level of the xiphoid process. Cardiac output determined using direct Fick-oxygen principle was calculated by direct measurement of oxygen consumption (VO2) and invasive determination of the arterio-venous oxygen content difference. An excellent correlation (r=0.97) was found between CO(EV) and CO(F) (P<0.001). The slope of the regression equation [0.96 (SD 0.04)] was not significantly different from the line of identity. The bias between the two methods (CO(EV)-CO(F)) was 0.01 litre min(-1) and the limits of agreement, defined as the bias (2 SD), were -0.47 and +0.45 litre min(-1). CO(EV) demonstrates acceptable agreement with data derived from CO(F) in infants and children with congenital heart disease. The new technique is simple, completely non-invasive, and provides beat-to-beat estimation of CO.

  10. A rebreathing method for measuring lung volume, diffusing capacity and cardiac output in conscious small animals.

    PubMed

    Yilmaz, Cuneyt; Johnson, Robert L; Hsia, Connie C W

    2005-04-15

    We developed a multiple gas rebreathing technique for measuring lung diffusing capacity (DL(CO)), lung volume (V(L)) and cardiac output simultaneously in conscious spontaneously breathing small animals. Lung volume was measured from the dilution of methane (CH4) or sulfur hexafluoride (SF6) and verified independently by a helium washout technique. Cardiac output and DL(CO) were estimated from the uptake of acetylene and carbon monoxide, respectively. We tested guinea pigs at two levels of alveolar oxygen tension in order to estimate membrane diffusing capacity and pulmonary capillary blood volume by the Roughton-Forster technique. Results show that measured DL(CO) are consistent with reported values in anesthetized guinea pigs as well as with allometric comparison across species. Lung volume estimated from SF6 dilution agreed closely with that estimated independently from helium washout; however, lung volume estimated from CH4 dilution was systematically lower due to the addition of endogenously produced CH4 to the rebreathing system. We conclude that this technique can be used to measure resting lung function in conscious unsedated small animals.

  11. Measurements of cardiac output of an isolated heart using a specially designed turbine.

    PubMed

    Bunc, M; Suput, D; Zupanc, O; Rozman, J

    2000-01-01

    Cardiac output is one of the important parameters used in evaluation of heart function. A turbine which works on mechanical principles was designed. It is also suitable for cardiac output measurements on isolated pig hearts in cases where some other equipment is not, like on doppler effect based transducers. The basic principle of measuring liquid flow through a turbine is based on measurement of the time that elapses when the rotor rotates by one degree. For this purpose, the rotor is fitted with transparent foil with a ring of 360 short black lines printed close to its circumference. Two infrared light-emitting diodes are mounted on one side of the foil and two photo-transistors, used as sensors of the transmitted infrared light, are mounted on the other. Voltage-regulated output ranging from 0 to +/- 2048 V at one revolution per second gives 500 mV at the output (changeable by programming), calculating time 2 ms, 1 mV resolution (11 bits), with an external power supply of 5 V. The turbine showed a linear response at a continuous saline flow up to 3000 ml min-1 at pressure loads of between 20 and 220 cm H2O. Pressure drop across the turbine depends on the volume flow and was 1 mm Hg at 100 ml min-1 and 3 mm Hg at 7000 ml min-1. A rotating movement 1.25 x 10(-4) kg m2 s-1 was calculated. The lowest volume change of a bolus of saline solution, detected by the turbine, was 1.6 ml.

  12. A comparison of methods for the measurement of cardiac output and blood oxygen content.

    PubMed

    Douglas, I R; MacDonald, J A; Milligan, G F; Mellon, A; Ledingham, I M

    1975-04-01

    A comparison has been made between the recently introduced thermal dilution method for measurement of cardiac output and the standard dye dilution technique. Two relatively new methods of measurement of blood oxygen content, one involving the measurement of oxygen tension after release of oxygen by carbon monoxide, and the other the measurement of current flow upon reduction of oxygen in a galvanic cell, have been compared with a standard indirect method of measurement of blood oxygen content. All three new methods fulfilled the criteria of accuracy and simplicity and compared favourably with the standard methods. Of the two new methods for measurement of oxygen content, that involving reduction of oxygen in a galvanic cell was superior by virtue of compactness and speed of operation.

  13. A comparison between freon and acetylene rebreathing for measuring cardiac output.

    PubMed

    Bonde-Petersen, F; Norsk, P; Suzuki, Y

    1980-11-01

    Cardiac output (CO) was measured in 10 young, healthy male subjects during rest and submaximal exercise on a bicycle ergometer by rebreathing a 2.0-2.8 l (ATPS) gas mixture of acetylene (0.7-1.2%), freon-22 (3-4.2%), argon (6-7%), and oxygen (ca. 40%) in nitrogen. End tidal gas fractions were measured by a mass spectrometer. Argon was used as an inert, insoluble gas for corrections of end tidal acetylene-, freon-, and oxygen fractions. The acetylene results corresponded to cardiac outputs found in literature (6.06 +/- 0.20 l/min, at rest and 15.05 +/- 0.44 l/min at 150 W). The freon values followed those of acetylene but were systematically lower by 0.74 l/min at rest and 1.20 l/min at 150 W. A forced respiratory rate (30-32/min) increased CO and VO2 during rebreathing at rest and lower exercise levels, while a spontaneous respiratory rate (14/min at rest and 22/min at 150 W) did not change VO2 during rebreathing compared to Douglas measurements at steady state. We conclude that freon can be used as the inert, soluble gas in the rebreathing procedure and recommend a spontaneous respiratory rate.

  14. Measurement of cardiac output in ventricular rupture following acute myocardial infarction--pulmonary artery catheter vs transpulmonary thermodilution--a case report.

    PubMed

    Schwarzkopf, Konrad; Simon, Stefan; Preussler, Niels-Peter; Hüter, Lars

    2009-02-01

    We compared the cardiac output measured by the transpulmonary aortic single indicator thermodilution method with that by the pulmonary artery catheterization in a patient with ventricular septal rupture after acute myocardial infarction. Though the former cardiac output was lower than the latter, in the presence of the ventricular septal rupture, the cardiac outputs were equal after the rupture was closed. This indicates that, while the cardiac output measured by the pulmonary artery catheter is influenced by the ventricular left-to-right shunt, transpulmonary aortic thermodilution method measures the true cardiac output of the left heart, which is responsible for organ perfusion.

  15. Comparison of pulmonary artery and transpulmonary thermodilution cardiac output measurements in unsedated newborn calves.

    PubMed

    Kutter, Annette P N; Jud Schefer, Rahel S; Bircher, Barbara; Bleul, Uli; Bettschart-Wolfensberger, Regula

    2015-11-01

    To compare the agreement, repeatability and trending ability of transpulmonary thermodilution (TPTD) and pulmonary artery thermodilution (PATD) cardiac output (Q˙t) measurements in unsedated newborn calves. Prospective experimental trial. Eight newborn calves weighing a median (range) of 53 (46-59) kg. Pulmonary and femoral artery thermodilution catheters were placed under local anaesthesia. A total of 382 PATD and TPTD Q˙t measurements were performed simultaneously. Cardiac output was influenced by intravenous doxapram and theophylline in a randomized crossover fashion. Bland-Altman analysis for multiple comparisons, concordance and polar plots were used to assess TPTD against PATD. Median (range) cardiac index values measured with PATD and TPTD were 197 mL kg(-1) minute(-1) (74-335 mL kg(-1) minute(-1)) and 196 mL kg(-1) minute(-1) (59-395 mL kg(-1) minute(-1)), respec-tively. A small mean bias of -3 mL kg(-1) minute(-1) with limits of agreement (LOA) of -64 to 58 mL kg(-1) minute(-1) and a percentage error of 31% were found. Eighty-two mean values were calculated. This reduced the LOA to -50 to 41 mL kg(-1) minute(-1) with a similar small bias and a percentage error of 23%. Mean TPTD tracked changes in Q˙t compared with mean PATD with 90% concordance, a mean polar angle of 6° and radial LOA of 43°, indicating marginal trending ability. Keeping the femoral artery catheter patent and obtaining acceptable measurements were very challenging because the calves were not used to being restrained. Calf movement had less influence on PATD. We recommend that PATD remains the reference method to measure Q˙t in unsedated newborn calves. However, the robust results of the evaluation of the less invasive TPTD technique warrants further evaluation taking into account the difficulties reported in this study. © 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.

  16. Pulse contour cardiac output monitoring in acute heart failure patients : Assessment of hemodynamic measurements.

    PubMed

    Wernly, Bernhard; Lichtenauer, Michael; Franz, Marcus; Fritzenwanger, Michael; Kabisch, Bjoern; Figulla, Hans-Reiner; Jung, Christian

    2016-12-01

    Heart failure is known to be a major public health problem. Fluid redistribution contributes to acute heart failure; therefore, knowledge of hemodynamic parameters could be important for optimizing outcomes. The pulse contour cardiac output monitor PiCCO uses the single thermal indicator technique and pulse contour analysis to calculate hemodynamic parameters of preload, afterload, cardiac output, systemic vascular resistance and extravascular lung water. We primarily aimed to describe values and parameters seen in acute heart failure patients admitted to the intensive care unit (ICU) and secondly to investigate associations between hemodynamic measurements and survival data. In this study 420 consecutive patients admitted to a tertiary medical university hospital ICU between January 2004 and December 2009 were retrospectively investigated. The study sample was divided into two subgroups: patients monitored by PiCCO (n = 47) and those not monitored by thermodilution measurements (n = 373). No predetermined treatment algorithm based on knowledge obtained by the PiCCO monitor was used and measurements were individually interpreted by the treating physician. The PiCCO monitor measurements were carried out according to manufacturer's directions. Patients with PiCCO monitoring were clinically in poorer health with a mean simplified acute physiology score II (SAPS2) of 45 ± 17 vs. 56 ± 20 (p < 0.01). The ICU mortality (22 % vs. 38 %, p = 0.02) and, at least as a tendency, long-term-mortality were increased in patients monitored by PiCCO (RR 1.49, 95 % CI 0.96-2.31, p = 0.08). We provide hemodynamic measurements in acute heart failure patients: cardiac index (2.7 ± 1.2 l/min/m²) was reduced, preload and extravascular lung water index (EVLWI, 11.5 ± 5.1 ml/kg body weight), representing lung edema, were increased. We provide real world values for PiCCO parameters in acutely decompensated heart failure. In our study patients who were clinically in

  17. Effects of body temperature on accuracy of continuous cardiac output measurements.

    PubMed

    Luchette, F A; Porembka, D; Davis, K; Branson, R D; James, L; Hurst, J M; Johannigman, J A; Campbell, R S

    2000-01-01

    Intermittent measurement of cardiac output is routine in the critically ill surgical patient. A new catheter allows real-time continuous measurement of cardiac output. This study evaluated the impact of body temperature variation on the accuracy of these measurements compared to standard intermittent bolus thermodilution technique. This prospective study in a university hospital surgical intensive care unit included 20 consecutive trauma patients. Data were collected with pulmonary artery catheters, which allowed both continuous (COC) and bolus (COB) thermodilution measurements. The catheter was placed through either the subclavian or internal jugular vein. Measurements for COB were performed using a bolus (10 cm3) of ice-cold saline with a closed-injectate delivery system at end-expiration. Computer-generated curves were created on a bedside monitor, and the average of three measurements within 10% of one another was used as COB. COC was determined as the average of the displayed CO before and after thermodilution CO measurements. Body temperature was measured from the pulmonary artery catheter and was grouped as < or =36.5 degrees C, 36.6-38.4 degrees C, and > or =38.5 degrees C. COB and COC were compared for agreement by plotting the mean of the differences (COB - COC) between the methods. The differences were plotted against the average of each pair and analyzed with linear regression. One hundred seventy-eight paired measurements were made over a period of 1 to 3 days. CO ranged from 3.7 to 15.5 L/min. Eighty-one percent of measurements were at a temperature of 36.5-38.4 degrees C. Approximately 7% of measurements were at a temperature below 36.5 degrees C and 11.2% were in patients with a core temperature above 38.5 degrees C. Correlation between the two techniques was 0.96, 0.91, and 0.82 for temperatures of < or =36.5 degrees C, 36.6-38.4 degrees C, and > or = 38.5 degrees C, respectively. In conclusion, the COC measurements correlate well with COB in

  18. Hybrid measurement to achieve satisfactory precision in perioperative cardiac output monitoring.

    PubMed

    Peyton, P

    2014-05-01

    Advanced haemodynamic monitoring employing minimally invasive cardiac output measurement may lead to significant improvements in patient outcomes in major surgery. However, the precision (scatter) of measurement of available generic technologies has been shown to be unsatisfactory with percentage error of agreement with bolus thermodilution (% error) of 40% to 50%. Simultaneous measurement and averaging by two or more technologies may reduce random measurement scatter and improve precision. This concept, called the hybrid method, was tested by comparing accuracy and precision of measurement relative to bolus thermodilution using combinations of three component methods. Thirty patients scheduled for either elective cardiac surgery or liver transplantation were studied. Agreement with simultaneous bolus thermodilution of hybrid combinations of continuous thermodilution (QtCCO) or Vigeleo™/FloTrac™ pulse contour measurement (QtFT) with pulmonary Capnotracking (QtCO2) was assessed pre- and post-cardiopulmonary bypass or pre- and post-reperfusion of the donor liver and compared with that of the component methods alone. Hybridisation of QtCO2 (% error 42.2) and QtCCO (% error 51.3) achieved significantly better precision (% error 31.3) than the component methods (P=0.0004) and (P=0.0195). Due to poor inherent precision of QtFT (% error 82.8), hybrid combination of QtFT with QtCO2 did not result in better precision than QtCO2 alone. Hybrid measurement can approach a 30% error, which is recommended as the upper limit for acceptability. This is a practical option where at least one component method, such as Capnotracking, is automated and does not increase the cost or complexity of the measurement process.

  19. Noninvasive cardiac output measurement by inert gas rebreathing in suspected pulmonary hypertension.

    PubMed

    Farina, Stefania; Teruzzi, Giovanni; Cattadori, Gaia; Ferrari, Cristina; De Martini, Stefano; Bussotti, Maurizio; Calligaris, Giuseppe; Bartorelli, Antonio; Agostoni, Piergiuseppe

    2014-02-01

    The objective of this study was to evaluate inert gas rebreathing (IGR) reliability in cardiac output (CO) measurement compared with Fick method and thermodilution. IGR is a noninvasive method for CO measurement; CO by IGR is calculated as pulmonary blood flow plus intrapulmonary shunt. IGR may be ideal for follow-up of patients with pulmonary hypertension (PH), sparing the need of repeated invasive right-sided cardiac catheterization. Right-sided cardiac catheterization with CO measurement by thermodilution, Fick method, and IGR was performed in 125 patients with possible PH by echocardiography. Patients were grouped according to right-sided cardiac catheterization-measured mean pulmonary and wedge pressures: normal pulmonary arterial pressure (n = 20, mean pulmonary arterial pressure = 18 ± 3 mm Hg, pulmonary capillary wedge pressure = 11 ± 5 mm Hg), PH and normal pulmonary capillary wedge pressure (PH-NW, n = 37 mean pulmonary arterial pressure = 42 ± 13 mm Hg, pulmonary capillary wedge pressure = 11 ± 6 mm Hg), and PH and high pulmonary capillary wedge pressure (PH-HW, n = 68, mean pulmonary arterial pressure = 37 ± 9 mm Hg, pulmonary capillary wedge pressure = 24 ± 6 mm Hg). Thermodilution and Fick measurements were comparable. Fick and IGR agreement was observed in normal pulmonary arterial pressure (CO = 4.10 ± 1.14 and 4.08 ± 0.97 L/min, respectively), whereas IGR overestimated Fick in patients with PH-NW and those with PH-HW because of intrapulmonary shunting overestimation in hypoxemic patients. When patients with arterial oxygen saturation (SO2) ≤90% were excluded, IGR and Fick agreement improved in PH-NW (CO = 4.90 ± 1.70 and 4.76 ± 1.35 L/min, respectively) and PH-HW (CO = 4.05 ± 1.04 and 4.10 ± 1.17 L/min, respectively). In hypoxemic patients, we estimated pulmonary shunt as Fick - pulmonary blood flow and calculated shunt as: -0.2423 × arterial SO2 + 21.373 L/min. In conclusion, IGR is reliable for CO measurement in patients with PH

  20. The normal ranges of cardiovascular parameters measured using the ultrasonic cardiac output monitor.

    PubMed

    Cattermole, Giles N; Leung, P Y Mia; Ho, Grace Y L; Lau, Peach W S; Chan, Cangel P Y; Chan, Stewart S W; Smith, Brendan E; Graham, Colin A; Rainer, Timothy H

    2017-03-01

    The ultrasonic cardiac output monitor (USCOM) is a noninvasive transcutaneous continuous wave Doppler method for assessing hemodynamics. There are no published reference ranges for normal values in adults (aged 18-60 years) for this device. This study aimed to (1) measure cardiovascular indices using USCOM in healthy adults aged 18-60 years; (2) combine these data with those for healthy children (aged 0-12), adolescents (aged 12-18), and the elderly (aged over 60) from our previously published studies in order to present normal ranges for all ages, and (3) establish normal ranges of USCOM-derived variables according to both weight and age. This was a population-based cross-sectional observational study of healthy Chinese subjects aged 0.5-89 years in Hong Kong. USCOM scans were performed on all subjects, to produce measurements including stroke volume, cardiac output, and systemic vascular resistance. Data from previously published studies (children, adolescents, and the elderly) were included. Normal ranges were defined as lying between the 2.5th and 97.5th percentiles. A total of 2218 subjects were studied (mean age = 16.4, range = 0.5-89; 52% male). From previous studies, 1197 children (aged 0-12, 55% male), 590 adolescents (aged 12-18, 49% male), and 77 elderly (aged 60-89, 55% male) were included. New data were collected from 354 adults aged 18-60 (47% male). Normal ranges are presented according to age and weight. We present comprehensive normal ranges for hemodynamic parameters obtained with USCOM in healthy subjects of all ages from infancy to the elderly.

  1. Differences between directly measured and calculated values for cardiac output in the dogfish: a criticism of the Fick method.

    PubMed

    Metcalfe, J D; Butler, P J

    1982-08-01

    Cardiac output has been measured directly, and calculated by the Fick method, during normoxia and hypoxia in six artificially perfused dogfish (Scyliorhinus canicula) in an attempt to estimate the accuracy of this method in fish. The construction and operation of a simple extra-corporeal cardiac bypass pump is described. This pump closely mimics the flow pulse profiles of the fish's own heart and allows complete control of both cardiac stroke volume and systolic and diastolic periods. During normoxia (PO2 = 21 kPa) there was no significant difference between directly measured and calculated values for cardiac output. However, some shunting of blood past the respiratory surface of the gills may have been obscured by cutaneous oxygen uptake. In response to hypoxia (PO2 = 8.6 kPa) there is either a decrease in the amount of blood being shunted past the respiratory surface of the gills and/or an increase in cutaneous oxygen uptake such that the Fick calculated value for cardiac output is on average 38% greater than the measured value. It is proposed that the increase in the levels of circulating catecholamines that is reported to occur in response to hypoxia in this species may play an important role in the observed response to hypoxia. The results are discussed in terms of their implications for the calculation of cardiac output by the Fick principle in fish.

  2. Noninvasive measurement of cardiac output during exercise in children with tetralogy of Fallot.

    PubMed

    Marcuccio, Elisa; Arora, Gaurav; Quivers, Eric; Yurchak, Mary Kay; McCaffrey, Francis

    2012-10-01

    In patients with surgically repaired tetralogy of Fallot (TOF), reported peak oxygen consumption (VO(2)) is decreased compared with control subjects. The measurement of exercise cardiac output (CO) could be a useful adjunct for assessing cardiovascular fitness. There are few data assessing noninvasive CO, cardiac index (CI), and stroke volume (SV) during exercise for these patients. This study sought to measure noninvasive CI and SV during rest and exercise in children with repaired TOF. The authors compared 21 asymptomatic children with repaired TOF ages 11-17 years during rest and exercise and 42 gender- and age-matched healthy control children without structural heart disease. Using a Bruce exercise protocol, exercise data were measured noninvasively by a novel inert gas rebreathing technique including peak duration and heart rate, as well as VO(2), CO, CI, and SV measured at 90 % of peak predicted theoretical heart rate (90 % ppHR). Statistical correlation between peak VO(2) and CI was performed. At baseline, there was no statistically significant difference in any of the measures between the groups. At 90 % ppHR, there was an increase in CI during exercise of 140 % in the TOF children and 180 % in the control children. During exercise, SV changed minimally in the patient group, whereas it increased more than 30 % in the control children. At 90 % ppHR, the patient group showed an increase in VO(2) during exercise similar to that of their healthy peers. The patients had a significantly shorter peak exercise duration than normal control subjects. The patients had a lower CI during exercise because they were less able to increase SV. Therefore, at similar heart rates, patients who have had TOF repair must rely on increased peripheral muscle extraction, with a higher arteriovenous oxygen difference (SaO(2)-MvO(2)) during exercise, which may limit peak exercise capacity. In this cohort of TOF patients, noninvasive CI measurement was feasible, and correlation with VO

  3. Equipment review: New techniques for cardiac output measurement – oesophageal Doppler, Fick principle using carbon dioxide, and pulse contour analysis

    PubMed Central

    Berton, Christine; Cholley, Bernard

    2002-01-01

    Measuring cardiac output is of paramount importance in the management of critically ill patients in the intensive care unit and of 'high risk' surgical patients in the operating room. Alternatives to thermodilution are now available and are gaining acceptance among practitioners who have been trained almost exclusively in the use of the pulmonary artery catheter. The present review focuses on the principles, advantages and limitations of oesophageal Doppler, Fick principle applied to carbon dioxide, and pulse contour analysis. No single method stands out or renders the others obsolete. By making cardiac output easily measurable, however, these techniques should all contribute to improvement in haemodynamic management. PMID:12133181

  4. [Optimal electrode array for ambulatory measuring of cardiac output based on the electrical impedance method].

    PubMed

    Song, Yilin; Gao, Shumei; Ikrashi, Akira; Yamakoshi, Ken-ichi

    2011-02-01

    Principle of ambulatory cardiac output (CO) measuring technique is introduced in this paper. A lot of experimental studies of the current distribution on the thorax under the condition that the current injection electrodes were adhered to different positions were carried out by using a developed multi-channel impedance mapping system. The static impedance contour maps (Zo-map) and its pulsatile component contour maps (deltaZ-map) under different measuring conditions were analyzed, and the applicability of a two-compartment coaxial cylindrical model using a spot-electrode array instead of the conventional band-electrode array for ambulatory CO measurement, as well as the optimal spot-electrode array, were discussed. Based on the experimental results and the daily use of the ambulatory CO measuring technique, the optimal spot-electrode array meeting the condition of the two-compartment coaxial cylindrical model was determined as that a pair of spot-electrodes for current injection was located on the positions behind the ears and on the right lower abdomen, and a pair of spot-electrodes for voltage pick-up places on the medial portion at the level of clavicle and on the portion above the xiphisternum.

  5. Quantification of mitral regurgitation by automated cardiac output measurement: experimental and clinical validation

    NASA Technical Reports Server (NTRS)

    Sun, J. P.; Yang, X. S.; Qin, J. X.; Greenberg, N. L.; Zhou, J.; Vazquez, C. J.; Griffin, B. P.; Stewart, W. J.; Thomas, J. D.

    1998-01-01

    OBJECTIVES: To develop and validate an automated noninvasive method to quantify mitral regurgitation. BACKGROUND: Automated cardiac output measurement (ACM), which integrates digital color Doppler velocities in space and in time, has been validated for the left ventricular (LV) outflow tract but has not been tested for the LV inflow tract or to assess mitral regurgitation (MR). METHODS: First, to validate ACM against a gold standard (ultrasonic flow meter), 8 dogs were studied at 40 different stages of cardiac output (CO). Second, to compare ACM to the LV outflow (ACMa) and inflow (ACMm) tracts, 50 normal volunteers without MR or aortic regurgitation (44+/-5 years, 31 male) were studied. Third, to compare ACM with the standard pulsed Doppler-two-dimensional echocardiographic (PD-2D) method for quantification of MR, 51 patients (61+/-14 years, 30 male) with MR were studied. RESULTS: In the canine studies, CO by ACM (1.32+/-0.3 liter/min, y) and flow meter (1.35+/-0.3 liter/min, x) showed good correlation (r=0.95, y=0.89x+0.11) and agreement (deltaCO(y-x)=0.03+/-0.08 [mean+/-SD] liter/min). In the normal subjects, CO measured by ACMm agreed with CO by ACMa (r=0.90, p < 0.0001, deltaCO=-0.09+/-0.42 liter/min), PD (r=0.87, p < 0.0001, deltaCO=0.12+/-0.49 liter/min) and 2D (r=0.84, p < 0.0001, deltaCO=-0.16+/-0.48 liter/min). In the patients, mitral regurgitant volume (MRV) by ACMm-ACMa agreed with PD-2D (r= 0.88, y=0.88x+6.6, p < 0.0001, deltaMRV=2.68+/-9.7 ml). CONCLUSIONS: We determined that ACM is a feasible new method for quantifying LV outflow and inflow volume to measure MRV and that ACM automatically performs calculations that are equivalent to more time-consuming Doppler and 2D measurements. Additionally, ACM should improve MR quantification in routine clinical practice.

  6. Quantification of mitral regurgitation by automated cardiac output measurement: experimental and clinical validation

    NASA Technical Reports Server (NTRS)

    Sun, J. P.; Yang, X. S.; Qin, J. X.; Greenberg, N. L.; Zhou, J.; Vazquez, C. J.; Griffin, B. P.; Stewart, W. J.; Thomas, J. D.

    1998-01-01

    OBJECTIVES: To develop and validate an automated noninvasive method to quantify mitral regurgitation. BACKGROUND: Automated cardiac output measurement (ACM), which integrates digital color Doppler velocities in space and in time, has been validated for the left ventricular (LV) outflow tract but has not been tested for the LV inflow tract or to assess mitral regurgitation (MR). METHODS: First, to validate ACM against a gold standard (ultrasonic flow meter), 8 dogs were studied at 40 different stages of cardiac output (CO). Second, to compare ACM to the LV outflow (ACMa) and inflow (ACMm) tracts, 50 normal volunteers without MR or aortic regurgitation (44+/-5 years, 31 male) were studied. Third, to compare ACM with the standard pulsed Doppler-two-dimensional echocardiographic (PD-2D) method for quantification of MR, 51 patients (61+/-14 years, 30 male) with MR were studied. RESULTS: In the canine studies, CO by ACM (1.32+/-0.3 liter/min, y) and flow meter (1.35+/-0.3 liter/min, x) showed good correlation (r=0.95, y=0.89x+0.11) and agreement (deltaCO(y-x)=0.03+/-0.08 [mean+/-SD] liter/min). In the normal subjects, CO measured by ACMm agreed with CO by ACMa (r=0.90, p < 0.0001, deltaCO=-0.09+/-0.42 liter/min), PD (r=0.87, p < 0.0001, deltaCO=0.12+/-0.49 liter/min) and 2D (r=0.84, p < 0.0001, deltaCO=-0.16+/-0.48 liter/min). In the patients, mitral regurgitant volume (MRV) by ACMm-ACMa agreed with PD-2D (r= 0.88, y=0.88x+6.6, p < 0.0001, deltaMRV=2.68+/-9.7 ml). CONCLUSIONS: We determined that ACM is a feasible new method for quantifying LV outflow and inflow volume to measure MRV and that ACM automatically performs calculations that are equivalent to more time-consuming Doppler and 2D measurements. Additionally, ACM should improve MR quantification in routine clinical practice.

  7. Accuracy of thermodilution measurement of cardiac output in low flows applicable to feline and small canine patients.

    PubMed Central

    Dyson, D H; McDonnell, W N; Horne, J A

    1984-01-01

    A model system of feline or small canine cardiac output was used to produce known liquid flow rates in the range of 100 to 750 mL/min for comparison against a thermodilution technique of flow measurement. Thermal indicator size was decided by the thermal time concentration curve detected by the Edwards 9520A cardiac output computer. Ten consecutive readings for each flow were made. Regression analysis and Student's t-test were used to evaluate the results. The computer was found to give good correlation with the accurate flow measured by a graduated cylinder over a period of time (r = 0.99). An error of less than 7% overestimation of flow by thermodilution was found with flows greater than 200 mL/min (p less than 0.05). A significant error of more than 20% overestimation of the actual flow occurred with flows less than 200 mL/min (p less than 0.05). The Edwards 9520A computer was compared to the older Edwards 9510A model by averaged triplicate measurements at six different cardiac outputs in an anesthetized cat. The measurements were not significantly different (p less than 0.01). Thermodilution using an Edwards computer proves to be a promising tool in the measurement of low flows applicable to feline and small canine cardiac outputs. PMID:6509371

  8. Comparison and reliability of two non-invasive acetylene uptake techniques for the measurement of cardiac output.

    PubMed

    Dibski, D W; Smith, D J; Jensen, R; Norris, S R; Ford, G T

    2005-08-01

    Comparison and reliability of two non-invasive acetylene uptake techniques for the measurement of cardiac output. Thirteen trained male cyclists performed CO2 rebreathing (CO2RB) at intensities from rest to 200 W, and open-circuit acetylene uptake (OpCirc) and single-breath acetylene uptake (SB) at intensities from rest to 300 W, with all procedures using 50 W increments. Oxygen consumption VO2 cardiac output Q and heart rate (HR), were measured at each stage, and the values for each variable were compared within each intensity to determine reliability of the measuring device. Both the OpCirc and SBs were shown to be reliable measures of cardiac output (r = 0.95 and 0.92, respectively) with decreasing coefficients of variation (CV) as intensity increased, and were similar to published data. The Q-VO2 relationship using the SB diverged from the regression line for OpCirc and CO2RB. Linear regression of the Q--VO2 relationship for CO2RB was y = 6.18 x VO2 + 2.59 for OpCirc was y = 6.12 x VO2 + 2.98 and for SB was y = 5.05 x VO2 + 3.76. The OpCirc and SBs were both shown to be reliable techniques for measuring cardiac output, comparable to previously reported cardiac output measurements, and suitable for use in exercise testing. However, the SB, requiring a constant, slow exhalation rate, made the procedure difficult to perform at higher exercise intensities.

  9. The ability of the Vigileo-FloTrac system to measure cardiac output and track cardiac output changes during one-lung ventilation.

    PubMed

    Suehiro, Koichi; Tanaka, Katsuaki; Yamada, Tokuhiro; Matsuura, Tadashi; Mori, Takashi; Funao, Tomoharu; Nishikawa, Kiyonobu

    2015-06-01

    This study was aimed at comparing the cardiac output (CO) measured by the Vigileo™-FloTrac™ system with that estimated by the thermodilution pulmonary artery catheter (PAC) during one-lung ventilation (OLV) and determining the reliability of this system in tracking phenylephrine-induced CO changes during OLV. Sixteen patients scheduled for descending aorta replacement were enrolled. The study was performed 30 min after starting OLV under stable hemodynamic conditions. We recorded hemodynamic variables, CO measured by PAC thermodilution (ICO), CO measured by Vigileo™-FloTrac™ system (Version 3.02, Edwards Lifesciences, Irvine, CA, USA) (APCO), and systemic vascular resistance index (SVRI) before (T0) and after (T1) phenylephrine (100 μg) administration. We used Bland-Altman analysis to compare ICO and APCO. Polar plot and four-quadrant plot were used to assess the tracking ability of the Vigileo™-FloTrac™ system against ICO after administration of phenylephrine. Ninety hemodynamic interventions were performed. Bland-Altman analysis revealed that the mean bias between APCO and ICO was 0.05 L/min and the percentage error, 46.9 %. Four-quadrant plot analysis showed a concordance rate of 24.7 %, while polar plot analysis showed that the concordance rate was 13.3 %; the angular bias, -45.9°; radial limit of agreement, 85.3°. The bias between APCO and ICO was significantly correlated with the SVRI value (p < 0.001, r(2) = 0.822). The reliability of the Vigileo™-FloTrac™ system during OLV to estimate CO and track phenylephrine-induced CO changes was not acceptable.

  10. Electrical velocimetry for noninvasive cardiac output and stroke volume variation measurements in dogs undergoing cardiovascular surgery.

    PubMed

    Sasaki, Kazumasu; Mutoh, Tatsushi; Mutoh, Tomoko; Kawashima, Ryuta; Tsubone, Hirokazu

    2017-01-01

    To compare electrical velocimetry (EV) noninvasive measures of cardiac output (CO) and stroke volume variation (SVV) in dogs undergoing cardiovascular surgery with those obtained with the conventional thermodilution technique using a pulmonary artery catheter. Prospective experimental trial. Seven adult Beagle dogs with a median weight of 13.6 kg. Simultaneous, coupled cardiac index (CI; CO indexed to body surface area) measurements by EV (CIEV) and the reference pulmonary artery catheter thermodilution method (CIPAC) were obtained in seven sevoflurane-anaesthetized, mechanically ventilated dogs undergoing experimental open-chest cardiovascular surgery for isolated right ventricular failure. Relationships between SVV or central venous pressure (CVP) and stroke volume (SV) were analysed to estimate fluid responsiveness. Haemodynamic data were recorded intraoperatively and before and after fluid challenge. Bland-Altman analysis of 332 matched sets of CI data revealed an overall bias and precision of - 0.22 ± 0.52 L minute(-1) m(-2) for CIEV and CIPAC (percentage error: 30.4%). Trend analysis showed a concordance of 88% for CIEV. SVV showed a significant positive correlation (r(2) = 0.442, p < 0.0001) with SV changes to a volume loading of 200 mL, but CVP did not (r(2) = 0.0002, p = 0.94). Better prediction of SV responsiveness (rise of SV index of ≥ 10%) was observed for SVV (0.74 ± 0.09; p = 0.014) with a significant area under the receiver operating characteristic curve in comparison with CVP (0.53 ± 0.98; p = 0.78), with a cut-off value of 14.5% (60% specificity and 83% sensitivity). In dogs undergoing cardiovascular surgery, EV provided accurate CO measurements compared with CIPAC, although its trending ability was poor. Further, SVV by EV, but not CVP, reliably predicted fluid responsiveness during mechanical ventilation in dogs. Copyright © 2016 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia

  11. Determination of cardiac output by Doppler echocardiography.

    PubMed Central

    Ihlen, H; Amlie, J P; Dale, J; Forfang, K; Nitter-Hauge, S; Otterstad, J E; Simonsen, S; Myhre, E

    1984-01-01

    Cardiac output determined by Doppler echocardiography was compared with that determined by thermodilution at rest and during dobutamine infusion in 10 patients (group A) and by the Fick method at rest in 11 patients (group B). All patients had angina pectoris without valvular heart disease. Maximum spatial blood velocity and cross sectional aortic area were estimated by the Doppler technique and echocardiography. Cardiac output was calculated by multiplying blood velocity by aortic area at various levels in the ascending aorta. The best correlation of cardiac output between the invasive and non-invasive methods was obtained when maximum velocity in the aortic root and the aortic orifice area were used in the calculations. Cardiac output was considerably overestimated when area measurements in the aortic root were used. Images PMID:6689921

  12. Upright cardiac output measurements in the transition to weightlessness during parabolic flights.

    PubMed

    Limper, Ulrich; Gauger, Peter; Beck, Luis E J

    2011-04-01

    Aims of this study were: 1) to determine cardiac output by inert gas rebreathing (CO(reb)) during transition into 0 Gz in the standing position; and 2) to compare impedance cardiography (ICG) and pulse contour method (PCM) with CO(reb) as a reference method. We measured baseline CO(reb) and heart rate (HR) on the ground, and CO(reb), CO(pcm), CO(icg), and HR in standing and supine positions in the transition to weightlessness in six subjects. We conducted repeated measures ANOVA, Bland and Altman analysis, and analysis of percentage error of each data set. CO(reb) rose from 5.03 +/- 0.7 upright ground control to 11.45 +/- 3.6 L x min(-1) in 0 Gz. HR and stroke volume (SV) rose from 83 +/- 14 to 113 +/- 19 bpm and from 61 +/- 6 to 99 +/- 18 ml, respectively. Mean CO(reb), CO(pcm), and CO(icg) across all conditions were 10.45 +/- 3.04, 7.42 +/- 1.71, and 6.57 +/- 2.46 L x min(-1), respectively. Overall Bland and Altman analysis showed poor agreement for CO(pcm) and CO(icg) compared to CO(reb). Large bias for both comparisons indicated that both PCM and ICG underestimate the true CO value. Paired CO values of individual subjects showed a better correlation between methods and a broad bias range, indicating a preponderant role for large between-subjects variability. Repeated CO(reb) determinations in 1 Cz (i.e., when the cardiovascular system is in a steady state) should be used for calibration of the PCM and of ICG data. PCM and ICG can then be used to track CO dynamics during rapid changes of acceleration profiles.

  13. Cardiac output and systemic vascular resistance: Clinical assessment compared with a noninvasive objective measurement in children with shock.

    PubMed

    Razavi, Asma; Newth, Christopher J L; Khemani, Robinder G; Beltramo, Fernando; Ross, Patrick A

    2017-06-01

    To evaluate physician assessment of cardiac output and systemic vascular resistance in patients with shock compared with an ultrasonic cardiac output monitor (USCOM). To explore potential changes in therapy decisions if USCOM data were available using physician intervention answers. Double-blinded, prospective, observational study in a tertiary hospital pediatric intensive care unit. Forty children (<18years) admitted with shock, requiring ongoing volume resuscitation or inotropic support. Two to 3 physicians clinically assessed cardiac output and systemic vascular resistance, categorizing them as high, normal, or low. An investigator simultaneously measured cardiac index (CI) and systemic vascular resistance index (SVRI) with USCOM categorized as high, normal, or low. Overall agreement between physician and USCOM for CI (48.5% [κ = 0.18]) and SVRI (45.9% [κ = 0.16]) was poor. Interobserver agreement was also poor for CI (58.7% [κ = 0.33]) and SVRI (52.3% [κ = 0.28]). Comparing theoretical physician interventions to "acceptable" or "unacceptable" clinical interventions, based on USCOM measurement, 56 (21%) physician interventions were found to be "unacceptable." There is poor agreement between physician-assessed CI and SVRI and USCOM, with significant interobserver variability among physicians. Objective measurement of CI and SVRI may reduce variability and improve diagnostic accuracy. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Comparison between two methods for cardiac output measurement in propofol-anesthetized dogs: thermodilution and Doppler.

    PubMed

    Lopes, Patricia Cristina Ferro; Sousa, Marlos Gonçalves; Camacho, Aparecido Antonio; Carareto, Roberta; Nishimori, Celina T D; Santos, Paulo S P; Nunes, Newton

    2010-09-01

    To compare cardiac output (CO) measured by Doppler echocardiography and thermodilution techniques in spontaneously breathing dogs during continuous infusion of propofol. To do so, CO was obtained using the thermodilution method (CO(TD)) and Doppler evaluation of pulmonary flow (CO(DP)) and aortic flow (CO(DA)). Prospective cohort study. Eight adult dogs weighing 8.3 +/- 2.0 kg. Propofol was used for induction (7.5 +/- 1.9 mg kg(-1) IV) followed by a continuous rate infusion at 0.7 mg kg(-1) minute(-1). The animals were positioned in left lateral recumbency on an echocardiography table that allowed for positioning of the transducer at the 3rd and 5th intercostal spaces of the left hemithorax for Doppler evaluation of pulmonary and aortic valves, respectively. CO(DP) and CO(DA) were calculated from pulmonary and aortic velocity spectra, respectively. A pulmonary artery catheter was inserted via the jugular vein and positioned inside the lumen of the pulmonary artery in order to evaluate CO(TD). The first measurement of CO(TD), CO(DP) and CO(DA) was performed 30 minutes after beginning continuous infusion (T0) and then at 15-minute intervals (T15, T30, T45 and T60). Numeric data were submitted to two-way anova for repeated measurements, Pearson's correlation coefficient and Bland & Altman analysis. Data are presented as mean +/- SD. At T0, CO(TD) was lower than CO(DA). CO(DA) was higher than CO(TD) and CO(DP) at T30, T45 and T60. The difference between the CO(TD) and CO(DP), when all data were included, was -0.04 +/- 0.22 L minute(-1) and Pearson's correlation coefficient (r) was 0.86. The difference between the CO(TD) and CO(DA) was -0.87 +/- 0.54 L minute(-1) and r = 0.69. For CO(TD) and CO(DP), the difference was -0.82 +/- 0.59 L minute(-1) and r = 0.61. Doppler evaluation of pulmonary flow was a clinically acceptable method for assessing the CO in propofol-anesthetized dogs.

  15. The accuracy of PiCCO® in measuring cardiac output in patients under therapeutic hypothermia - Comparison with transthoracic echocardiography.

    PubMed

    Souto Moura, T; Aguiar Rosa, S; Germano, N; Cavaco, R; Sequeira, T; Alves, M; Papoila, A L; Bento, L

    2017-05-25

    Invasive cardiac monitoring using thermodilution methods such as PiCCO® is widely used in critically ill patients and provides a wide range of hemodynamic variables, including cardiac output (CO). However, in post-cardiac arrest patients subjected to therapeutic hypothermia, the low body temperature possibly could interfere with the technique. Transthoracic Doppler echocardiography (ECHO) has long proved its accuracy in estimating CO, and is not influenced by temperature changes. To assess the accuracy of PiCCO® in measuring CO in patients under therapeutic hypothermia, compared with ECHO. Thirty paired COECHO/COPiCCO measurements were analyzed in 15 patients subjected to hypothermia after cardiac arrest. Eighteen paired measurements were obtained at under 36°C and 12 at ≥36°C. A value of 0.5l/min was considered the maximum accepted difference between the COECHO and COPiCCO values. Under conditions of normothermia (≥36°C), the mean difference between COECHO and COPiCCO was 0.030 l/min, with limits of agreement (-0.22, 0.28) - all of the measurements differing by less than 0.5 l/min. In situations of hypothermia (<36°C), the mean difference in CO measurements was -0.426 l/min, with limits of agreement (-1.60, 0.75), and only 44% (8/18) of the paired measurements fell within the interval (-0.5, 0.5). The calculated temperature cut-off point maximizing specificity was 35.95°C: above this temperature, specificity was 100%, with a false-positive rate of 0%. The results clearly show clinically relevant discordance between COECHO and COPiCCO at temperatures of <36°C, demonstrating the inaccuracy of PiCCO® for cardiac output measurements in hypothermic patients. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

  16. Evaluation of a method utilizing PhysioFlow®, a novel signal morphology-based form of impedance cardiography, to measure cardiac output in the conscious beagle.

    PubMed

    Payseur, Jason D; Rigney, John J; Turner, Sandra L; Wu, XueJun; Murphy, Dennis J; Rossman, Eric I

    2016-01-01

    Currently, standard methods for measuring cardiac output are either invasive (i.e. flow probe) or are limited in terms of short measurement intervals and measurement variability (i.e. echocardiography). The ability to reliably measure cardiac output in a non-invasive manner in large animals would provide a valuable tool to expand functional cardiovascular endpoints in preclinical safety studies. PhysioFlow® is a novel method that uses waveform analysis of an impedance signal to measure cardiac output non-invasively. Unlike cardiac impedance techniques in the past, PhysioFlow® is not dependant on thoracic structure or basal thoracic impedance (Z0) and therefore this methodology is transferrable from human to animal models. Three tool compounds with known effects on cardiac output were administered to conscious beagle dogs to determine if the non-invasive PhysioFlow® system could detect the expected changes in stroke volume and cardiac output as determined by literature references using the current standard methodologies (e.g. aortic blood flow and thermodilution). The PhysioFlow® system was able to detect increases in cardiac output when dosed with 20μg/kg of Dobutamine, a decrease in cardiac output when dosed with 0.1mg/kg of Acepromazine, and no significant change in cardiac output when dosed with 2mg/kg of Minoxidil. These results are within expected ranges based on published literature (Stepien et al., 1995; Taylor et al., 2007). PhysioFlow®, a signal morphology-based impedance cardiography, can be utilized to reliably and non-invasively measure cardiac output in beagle dogs. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Authentication of Radial Versus Femoral Arterial Pressure Waveform-Derived Cardiac Output With Transesophageal Echocardiography-Derived Cardiac Output Measurements in Patients Undergoing On-Pump Coronary Bypass Surgery.

    PubMed

    Maddali, Madan Mohan; Waje, Niranjan Dilip; Sathiya, Panchatcharam Murthi

    2017-08-01

    The aim of this study was to ascertain if arterial waveform-derived cardiac output measurements from radial and femoral cannulation sites were reliable as compared with transesophageal echocardiography (TEE)-derived cardiac output (CO) values, and which of the CO measurements derived from radial and the femoral arterial pressure waveforms closely tracked simultaneously measured TEE-derived CO values. This study also aimed to ascertain if cardiopulmonary bypass (CPB) would impact the accuracy of arterial pressure-derived CO values from either of the 2 sites. A prospective observational study. Tertiary care cardiac center. Cardiac surgical patients undergoing on-pump primary coronary artery bypass surgery. Waveform-derived CO monitoring through radial and femoral artery cannulation using a FloTrac/Vigileo system. Twenty-seven consecutive cardiac surgical patients undergoing on-pump primary coronary artery bypass surgery were included in the study. Cardiac output was measured sequentially by the arterial pressure waveform analysis method from radial and femoral arterial sites and compared with simultaneously measured TEE-derived CO. Cardiac output data were obtained in triplicate at 6 predefined time intervals: before and after sternotomy, 5, 15, and 30 minutes after separation from CPB and prior to shifting the patient out of the operating room. The overall bias of the study was 0.11 and 0.27, the percentage error was 19.31 and 18.45, respectively, for radial and femoral arterial waveform-derived CO values as compared with TEE-derived CO measurements. The overall precision as compared with the TEE-derived CO values was 16.94 and 15.95 for the radial and femoral cannulation sites, respectively. The bias calculated by the Bland-Altman method suggested that CO measurements from the radial arterial site were in closer agreement with TEE-derived CO values at all time periods, and the relation was not affected by CPB. However, percentage error and precision calculations

  18. [Applicability of the two-compartment coaxial cylindrical model for ambulatory measuring of cardiac output with spot-electrodes].

    PubMed

    Song, Yilin; Gao, Shumei; Ikrashi, Akira; Yamakoshi, Ken-ichi

    2013-08-01

    The principle of ambulatory cardiac output (CO) measuring technique is introduced in this paper. Experimental studies about the applicability of the two-compartment coaxial cylindrical model for ambulatory measurement of cardiac output with spot-electrodes have been carried out with using our newly-developed multi-channel impedance mapping system. The key factors using a spot-electrode array instead of a conventional band-electrode array for non-invasive CO) measurement are elaborated. The variations of the electric impedance pulsatile component (deltaZ waveform) and the two kinds of typical modes of deltaZ distributions measured by six electrodes on the midsternal (midian) line from the medial portion at the level of clavicle to the portion above the xiphisternum are discussed. The applicability of the two-compartment coaxial cylindrical model for ambulatory measurement of CO with spot-electrodes is analyzed. Synthesizing the deltaZ distributions and their typical changing models on the midsternal (midian) line during blood inflowing into aorta is the optimal positions of a pair of spot-electrodes for voltage pick-up at the level of clavicle for the upper electrode and the position at the level of nipple for the lower electrode when spot-electrode is being used to measure non-invasive CO.

  19. Uncalibrated continuous cardiac output measurement in liver transplant patients: LiDCOrapid™ system versus pulmonary artery catheter.

    PubMed

    Costa, Maria Gabriella; Chiarandini, Paolo; Scudeller, Luigia; Vetrugno, Luigi; Pompei, Livia; Serena, Giovanni; Buttera, Stefania; Della Rocca, Giorgio

    2014-06-01

    The aim of the study was to assess the level of agreement between continuous cardiac output estimated by uncalibrated pulse-power analysis (PulseCOLiR) and intermittent (ICO) and continuous cardiac output (CCO) obtained using a pulmonary artery catheter (PAC). Prospective cohort study. University hospital intensive care unit. Twenty patients after liver transplantation. Pulmonary artery catheters were placed in all patients, and ICO and CCO were determined using thermodilution. PulseCOLiR measurements were made using a LiDCOrapid(TM) (LiDCO Ltd, Cambridge, UK). ICO data were determined after intensive care unit admission and every 8 hours until the 48th postoperative hour. CCO and PulseCOLiR measurements were recorded simultaneously at these same time intervals as well as hourly. For the 8-hour data set (140 data pairs), the mean bias and percentage errors (PE) were, respectively,-0.10 L/min and 39.2% for ICO versus PulseCOLiR and 0.79 L/min and 34.6% for CCO versus PulseCOLiR. For the hourly comparison of CCO versus PulseCOLiR (980 data pairs), the bias was 0.75 L/min and the PE 37%. To assess the ability to measure change, a 4-quadrant plot was produced for each pair of methods. The performance of PulseCOLiR was moderate in detecting changes in ICO. In conclusion, the uncalibrated PulseCOLir method should not be used as a substitute for the thermodilution technique for the monitoring of cardiac output in liver transplant patients. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Measurement of cardiac output in children by pressure-recording analytical method.

    PubMed

    Urbano, Javier; López, Jorge; González, Rafael; Solana, María José; Fernández, Sarah N; Bellón, José M; López-Herce, Jesús

    2015-02-01

    We evaluated two pressure-recording analytical method (PRAM) software versions (v.1 and v.2) to measure cardiac index (CI) in hemodynamically stable critically ill children and investigate factors that influence PRAM values. The working hypothesis was that PRAM CI measurements would stay within normal limits in hemodynamically stable patients. Ninety-five CI PRAM measurements were analyzed in 47 patients aged 1-168 months. Mean CI was 4.1 ± 1.4 L/min/m(2) (range 2.0-7.0). CI was outside limits defined as normal (3-5 L/min/m(2)) in 53.7% of measurements (47.8% with software v.1 and 69.2% with software v.2, p = 0.062). Moreover, 14.7% of measurements were below 2.5 L/min/m(2), and 13.6% were above 6 L/min/m(2). CI was significantly lower in patients with a clearly visible dicrotic notch than in those without (3.7 vs. 4.6 L/min/m(2), p = 0.004) and in children with a radial arterial catheter (3.5 L/min/m(2)) than in those with a brachial (4.4 L/min/m(2), p = 0.021) or femoral catheter (4.7 L/min/m(2), p = 0.005). By contrast, CI was significantly higher in children under 12 months (4.2 vs. 3.6 L/min/m(2), p = 0.034) and weighing under 10 kg (4.2 vs. 3.6 L/min/m(2), p = 0.026). No significant differences were observed between cardiac surgery patients and the rest of children. A high percentage of CI measurements registered by PRAM were outside normal limits in hemodynamically stable, critically ill children. CI measured by PRAM may be influenced by the age, weight, location of catheter, and presence of a dicrotic notch.

  1. Reliability of continuous cardiac output measurement during intra-abdominal hypertension relies on repeated calibrations: an experimental animal study

    PubMed Central

    Gruenewald, Matthias; Renner, Jochen; Meybohm, Patrick; Höcker, Jan; Scholz, Jens; Bein, Berthold

    2008-01-01

    Introduction Monitoring cardiac output (CO) may allow early detection of haemodynamic instability, aiming to reduce morbidity and mortality in critically ill patients. Continuous cardiac output (CCO) monitoring is recommended in septic or postoperative patients with high incidences of intra-abdominal hypertension (IAH). The aim of the present study was to compare the agreement between three CCO methods and a bolus thermodilution CO technique during acute IAH and volume loading. Methods Ten pigs were anaesthetised and instrumented for haemodynamic measurements. Cardiac output was obtained using CCO by pulse power analysis (PulseCO; LiDCO monitor), using CCO by pulse contour analysis (PCCO; PiCCO monitor) and using CCO by pulmonary artery catheter thermodilution (CCOPAC), and was compared with bolus transcardiopulmonary thermodilution CO (COTCP) at baseline, after fluid loading, at IAH and after an additional fluid loading at IAH. Whereas PulseCO was only calibrated at baseline, PCCO was calibrated at each experimental step. Results PulseCO and PCCO underestimated CO, as the overall bias ± standard deviation was 1.0 ± 1.5 l/min and 1.0 ± 1.1 l/min compared with COTCP. A clinically accepted agreement between all of the CCO methods and COTCP was observed only at baseline. Whereas IAH did not influence the CO, increased CO following fluid loading at IAH was only reflected by CCOPAC and COTCP, not by uncalibrated PulseCO and PCCO. After recalibration, PCCO was comparable with COTCP. Conclusions The CO obtained by uncalibrated PulseCO and PCCO failed to agree with COTCP during IAH and fluid loading. In the critically ill patient, recalibration of continuous arterial waveform CO methods should be performed after fluid loading or before a major change in therapy is initiated. PMID:18957114

  2. Pulse Wave Velocity and Cardiac Output vs. Heart Rate in Patients with an Implanted Pacemaker Based on Electric Impedance Method Measurement

    NASA Astrophysics Data System (ADS)

    Soukup, Ladislav; Vondra, Vlastimil; Viščor, Ivo; Jurák, Pavel; Halámek, Josef

    2013-04-01

    The methods and device for estimation of cardiac output and measurement of pulse wave velocity simultaneously is presented here. The beat-to-beat cardiac output as well as pulse wave velocity measurement is based on application of electrical impedance method on the thorax and calf. The results are demonstrated in a study of 24 subjects. The dependence of pulse wave velocity and cardiac output on heart rate during rest in patients with an implanted pacemaker was evaluated. The heart rate was changed by pacemaker programming while neither exercise nor drugs were applied. The most important result is that the pulse wave velocity, cardiac output and blood pressure do not depend significantly on heart rate, while the stroke volume is reciprocal proportionally to the heart rate.

  3. Validation of an ultrasound dilution technology for cardiac output measurement and shunt detection in infants and children.

    PubMed

    Lindberg, Lars; Johansson, Sune; Perez-de-Sa, Valeria

    2014-02-01

    To validate cardiac output measurements by ultrasound dilution technology (COstatus monitor) against those obtained by a transit-time ultrasound technology with a perivascular flow probe and to investigate ultrasound dilution ability to estimate pulmonary to systemic blood flow ratio in children. Prospective observational clinical trial. Pediatric cardiac operating theater in a university hospital. In 21 children (6.1 ± 2.6 kg, mean ± SD) undergoing heart surgery, cardiac output was simultaneously recorded by ultrasound dilution (extracorporeal arteriovenous loop connected to existing arterial and central venous catheters) and a transit-time ultrasound probe applied to the ascending aorta, and when possible, the main pulmonary artery. The pulmonary to systemic blood flow ratio estimated from ultrasound dilution curve analysis was compared with that estimated from transit-time ultrasound technology. Bland-Altman analysis of the whole cohort (90 pairs, before and after surgery) showed a bias between transit-time ultrasound (1.01 ± 0.47 L/min) and ultrasound dilution technology (1.03 ± 0.51 L/min) of -0.02 L/min, limits of agreement -0.3 to 0.3 L/min, and percentage error of 31%. In children with no residual shunts, the bias was -0.04 L/min, limits of agreement -0.28 to 0.2 L/min, and percentage error 19%. The pooled co efficient of variation was for the whole cohort 3.5% (transit-time ultrasound) and 6.3% (ultrasound dilution), and in children without shunt, it was 2.9% (transit-time ultrasound) and 4% (ultrasound dilution), respectively. Ultrasound dilution identified the presence of shunts (pulmonary to systemic blood flow ≠ 1) with a sensitivity of 100% and a specificity of 92%. Mean pulmonary to systemic blood flow ratio by transit-time ultrasound was 2.6 ± 1.0 and by ultrasound dilution 2.2 ± 0.7 (not significant). The COstatus monitor is a reliable technique to measure cardiac output in children with high sensitivity and specificity for detecting the

  4. Minimally invasive measurement of cardiac output during surgery and critical care: a meta-analysis of accuracy and precision.

    PubMed

    Peyton, Philip J; Chong, Simon W

    2010-11-01

    When assessing the accuracy and precision of a new technique for cardiac output measurement, the commonly quoted criterion for acceptability of agreement with a reference standard is that the percentage error (95% limits of agreement/mean cardiac output) should be 30% or less. We reviewed published data on four different minimally invasive methods adapted for use during surgery and critical care: pulse contour techniques, esophageal Doppler, partial carbon dioxide rebreathing, and transthoracic bioimpedance, to assess their bias, precision, and percentage error in agreement with thermodilution. An English language literature search identified published papers since 2000 which examined the agreement in adult patients between bolus thermodilution and each method. For each method a meta-analysis was done using studies in which the first measurement point for each patient could be identified, to obtain a pooled mean bias, precision, and percentage error weighted according to the number of measurements in each study. Forty-seven studies were identified as suitable for inclusion: N studies, n measurements: mean weighted bias [precision, percentage error] were: pulse contour N = 24, n = 714: -0.00 l/min [1.22 l/min, 41.3%]; esophageal Doppler N = 2, n = 57: -0.77 l/min [1.07 l/min, 42.1%]; partial carbon dioxide rebreathing N = 8, n = 167: -0.05 l/min [1.12 l/min, 44.5%]; transthoracic bioimpedance N = 13, n = 435: -0.10 l/min [1.14 l/min, 42.9%]. None of the four methods has achieved agreement with bolus thermodilution which meets the expected 30% limits. The relevance in clinical practice of these arbitrary limits should be reassessed.

  5. Diurnal variation and repeatability of arterial stiffness and cardiac output measurements in the third trimester of uncomplicated pregnancy.

    PubMed

    Osman, Mohamed W; Leone, Francesca; Nath, Mintu; Khalil, Asma; Webb, David R; Robinson, Thompson G; Mousa, Hatem A

    2017-07-14

    To investigate same day repeated measures and diurnal variation of arterial stiffness, cardiac output (CO), stroke volume (SV) and total peripheral resistance (TPR) during the third trimester of normal pregnancy. Pulse wave velocity (PWV) and augmentation index (AIx) were recorded using the Arteriograph, while CO, SV and TPR were recorded using noninvasive cardiac output monitoring. The measurements were obtained in the third trimester of pregnancy from 21 healthy pregnant women at four time points (morning, afternoon, evening and midnight) over a 24-h period. Triplicate measurements of 67 women were obtained at 5-min intervals to assess repeatability between measurements within a patient. Diurnal measurements of arterial stiffness for brachial AIx, aortic AIx and PWV were not statistically significantly different at any of the four time points. Estimated means (SD) for PWV at the four stated time points were 7.81 (2.05), 8.45 (1.68), 7.87 (1.74) and 7.64 m/s (1.15), respectively (P = 0.267). Estimates for AIx at those time points were 10.22 (15.62), 4.44 (10.07), 6.49 (10.92) and 8.40% (8.16), respectively (P = 0.295). Similarly, mean arterial pressure, SV, SV index and TPR did not show any evidence of diurnal variation. However, we observed that the mean CO, cardiac index (CI) and heart rate (HR) varied from morning to midnight; the mean CO, HR and CI increased significantly in the afternoon compared with the corresponding mean morning measurements in a similar fashion to HR. Mean (SD) CO estimates at the four stated time points were 5.90 (1.33), 6.38 (1.49), 6.18 (1.43) and 5.80 ml/min (1.19), respectively, (P < 0.001), whereas mean CI estimates were 3.65 (0.58), 3.93 (0.68), 3.81 (0.65), and 3.57 (0.48), respectively, (P < 0.001), and mean HR estimates were 95 (12), 98 (13), 95 (12) and 88 (12.98), respectively (P < 0.001). Triplicate measurements of 61 women in our repeatability study showed moderate-to-high correlation between

  6. Measurement of cardiac output during exercise in healthy, trained humans using lithium dilution and pulse contour analysis.

    PubMed

    Elliott, Adrian D; Skowno, Justin; Prabhu, Mahesh; Ansley, Les

    2012-10-01

    The aim of this study was to evaluate the use of pulse contour analysis calibrated with lithium dilution in a single device (LiDCO) for measurement of cardiac output (Q) during exercise in healthy volunteers. We sought to; (a) compare pulse contour analysis (PulseCO) and lithium indicator dilution (LiDCO) for the measurement of Q during exercise, and (b) assess the requirement for recalibration of PulseCO with LiDCO during exercise. Ten trained males performed multi-stage cycling exercise at intensities below and above ventilatory threshold before constant load maximal exercise to exhaustion. Uncalibrated PulseCO Q (Qraw) was compared to that calibrated with lithium dilution at baseline Qbaseline, during submaximal exercise below (Qlow) and above (Qhigh) ventilatory threshold, and at each exercise stage individually (Qexercise). There was a significant difference between Qbaseline and all other calibration methods during exercise, but not at rest. No significant differences were observed between other methods. Closest agreement with Qexercise was observed for Qhigh (bias ± limits of agreement: 4.8 ± 30.0%). The difference between Qexercise and both Qlow and Qraw was characterized by low bias (4-7%) and wide limits of agreement (> ± 40%). Calibration of pulse contour analysis with lithium dilution prior to exercise leads to a systematic overestimation of exercising cardiac output. A single calibration performed during exercise above the ventilatory threshold provided acceptable limits of agreement with an approach incorporating multiple calibrations throughout exercise. Pulse contour analysis may be used for Q measurement during exercise providing the system is calibrated during exercise.

  7. Thromboresistant surface coatings for the measurement of cardiac output through continuous low flow peripheral A-V shunts.

    PubMed Central

    Deeb, G M; Borovetz, H S; Griffith, B P; Hardesty, R L

    1980-01-01

    The dilution technique for determining cardiac output using indocyanine green dye is limited in patients weighing less than 20 kg because of the obligatory volume loss. Reproducible achieved using the green dye dilution method by the establishment of a low flow peripheral arteriovenous shunt. The shunt materials were treated with thromboresistant agents--TDMAC (7%) and albumin (1 g/dl)--to facilitate the use of this technique without heparin. For A-V shunt flow rates of 8-30 cc/min reproducible values of cardiac output were obtained for up to 38 hours which were in good agreement with determinations made using the conventional technique of dye dilution. PMID:6986120

  8. Seasonal variations of cardiac output in rats.

    PubMed

    Back, G; Strubelt, O

    1975-11-15

    Cardiac output of rats shows seasonal variations with low values in spring and summer and high ones in autumn and winter. The stroke volume was much more implicated in these changes than the heart rate. The seasonal changes of cardiac output are probably due to changes of thyroid function.

  9. The Treatment of Shock Based Upon Physiological Principles and Impedence Method for Measuring Cardiac Output in Shock

    DTIC Science & Technology

    1967-01-01

    cardiogenic shock following intracoronary artery microsphere embolization. The syndrome has been previously characterized by a fall in cardiac output and a...previously been oub- jected to and survived usually lethal cardiogenic shock, 5 dogs were selected. One month after intracoronary embolization, an LD, 0 0

  10. Continuous cardiac output measurement by un-calibrated pulse wave analysis and pulmonary artery catheter in patients with septic shock.

    PubMed

    Ganter, Michael T; Alhashemi, Jamal A; Al-Shabasy, Adel M; Schmid, Ursina M; Schott, Peter; Shalabi, Sanaa A; Badri, Ahmed M; Hartnack, Sonja; Hofer, Christoph K

    2016-02-01

    Septic shock is a serious medical condition. With increased concerns about invasive techniques, a number of non-invasive and semi-invasive devices measuring cardiac output (CO) have become commercially available. The aim of the present study was to determine the accuracy, precision and trending abilities of the FloTrac and the continuous pulmonary artery catheter thermodilution technique determining CO in septic shock patients. Consecutive septic shock patients were included in two centres and CO was measured every 4 h up to 48 h by FloTrac (APCO) and by pulmonary artery catheter (PAC) using the continuous (CCO) and intermittent (ICO) technique. Forty-seven septic shock patients with 326 matched sets of APCO, CCO and ICO data were available for analysis. Bland and Altman analysis revealed a mean bias ±2 SD of 0.0 ± 2.14 L min(-1) for APCO-ICO (%error = 34.5 %) and 0.23 ± 2.55 L min(-1) for CCO-ICO (%error = 40.4 %). Trend analysis showed a concordance of 85 and 81 % for APCO and CCO, respectively. In contrast to CCO, APCO was influenced by systemic vascular resistance and by mean arterial pressure. In septic shock patients, APCO measurements assessed by FloTrac but also the established CCO measurements using the PAC did not meet the currently accepted statistical criteria indicating acceptable clinical performance.

  11. A non-invasive cardiac output measurement as an alternative to the test bolus technique during CT angiography.

    PubMed

    Nijhof, W H; Hilbink, M; Jager, G J; Slump, C H; Rutten, M J C M

    2016-09-01

    To investigate the association between a non-invasive cardiac output (CO) measurement and the scan delay, as derived from a test bolus injection protocol. The secondary objective was to determine which factors affect the relationship between the CO and scan delay. Fifty-five patients referred for a contrast-enhanced (thorax-)abdomen CT examination were included in this feasibility study. A test bolus examination was performed prior to the abdominal CT. During the test bolus injection, the CO of the patient was measured using a non-invasive finger-cuff measurement. Associations were analysed using linear regression analyses. Age, gender, height, weight, and blood pressure were included as potential confounders. Linear regression analysis showed a negative and significant association between CO and delay. The regression formula was as follows: scan delay (seconds) = 26.8-1.6 CO (l/min), with a 95% CI between -2.3 and -1.0 (p<0.001). Weight appeared to be a confounder in this relation, and gender and blood pressure were effect modifiers. There was no interaction between scan delay and age, height and weight. There is a negative and significant association between the non-invasive CO measurement and the CT scan delay; however, to validate these findings a larger cohort study is needed to investigate whether the non-invasively determined scan delay is as accurate as the use of a test bolus. Copyright © 2016. Published by Elsevier Ltd.

  12. The effect of the prone maximal restraint position with and without weight force on cardiac output and other hemodynamic measures.

    PubMed

    Savaser, Davut J; Campbell, Colleen; Castillo, Edward M; Vilke, Gary M; Sloane, Christian; Neuman, Tom; Hansen, Allan V; Shah, Virag; Chan, Theodore C

    2013-11-01

    The prone maximal restraint (PMR) position has been used by law enforcement and emergency care personnel to restrain acutely combative or agitated individual. The position places the subject prone with wrists handcuffed behind the back and secured to the ankles. Prior work has indicated a reduction in inferior vena cava (IVC) diameter associated with this position when weight force is applied to the back. It is therefore possible that this position can negatively impact hemodynamic stability. We sought to measure the impact of PMR with and without weight force on measures of cardiac function including vital signs, oxygenation, stroke volume (SV), IVC diameter, cardiac output (CO) and cardiac index (CI). We conducted a randomized prospective cross-over experimental study of 25 healthy male volunteers (22-43 years of age) placed in 5 different body positions: supine (SU), prone (PR), prone maximal restraint with no weight force (PMR-0), prone maximal restraint with 50 lbs added to the subject's back (PMR-50), and prone maximal restraint with 100 lbs added to the subject's back (PMR-100) for 3 min. Heart rate (HR), blood pressure (BP), and oxygenation saturation (O2 sat) were monitored. In addition, echocardiography was performed to measure left ventricular outflow tract diameter (LVOTD), and SV, CO, and CI were then calculated. Data were analyzed using repeated measures ANOVA with pair-wise comparisons when appropriate to evaluate changes with each variable with respective positioning. Despite a small decrease in SV between SU and PMR positions, there were no statistically significant differences in CO between the 5 different positions. There were also no differences in CI between positions other than a small decrease when comparing SU and PMR-50 only (mean difference -0.39 L/stroke, p = 0.005). There was no evidence of hemodynamic compromise in any of the PMR positions when evaluating HR, MAP or O2 sat. PMR with and without weight force did not result in any

  13. Methods and apparatus for determining cardiac output

    NASA Technical Reports Server (NTRS)

    Cohen, Richard J. (Inventor); Mukkamala, Ramakrishna (Inventor); Sherman, Derin A. (Inventor)

    2010-01-01

    The present invention provides methods and apparatus for determining a dynamical property of the systemic or pulmonary arterial tree using long time scale information, i.e., information obtained from measurements over time scales greater than a single cardiac cycle. In one aspect, the invention provides a method and apparatus for monitoring cardiac output (CO) from a single blood pressure signal measurement obtained at any site in the systemic or pulmonary arterial tree or from any related measurement including, for example, fingertip photoplethysmography.According to the method the time constant of the arterial tree, defined to be the product of the total peripheral resistance (TPR) and the nearly constant arterial compliance, is determined by analyzing the long time scale variations (greater than a single cardiac cycle) in any of these blood pressure signals. Then, according to Ohm's law, a value proportional to CO may be determined from the ratio of the blood pressure signal to the estimated time constant. The proportional CO values derived from this method may be calibrated to absolute CO, if desired, with a single, absolute measure of CO (e.g., thermodilution). The present invention may be applied to invasive radial arterial blood pressure or pulmonary arterial blood pressure signals which are routinely measured in intensive care units and surgical suites or to noninvasively measured peripheral arterial blood pressure signals or related noninvasively measured signals in order to facilitate the clinical monitoring of CO as well as TPR.

  14. Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery.

    PubMed

    Broch, Ole; Renner, Jochen; Höcker, Jan; Gruenewald, Matthias; Meybohm, Patrick; Schöttler, Jan; Steinfath, Markus; Bein, Berthold

    2011-01-01

    Uncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB). Forty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CITPTD) or CI derived by pulse power analysis (CIPP), before and after calibration (CIPPnon-cal., CIPPcal.). Percentage changes of CI (ΔCITPTD, ΔCIPPnon-cal./PPcal.) were calculated to analyse directional changes. Before CPB there was no significant correlation between CIPPnon-cal. and CITPTD (r2 = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CIPPnon-cal. (r2 = 0.26, P < 0.0001). After CPB, CIPPcal. revealed a significant correlation compared with CITPTD (r2 = 0.77, P < 0.0001) with PE of 28%. Changes in CIPPcal. (ΔCIPPcal.) showed a correlation with changes in CITPTD (ΔCITPTD) only after CPB (r2 = 0.52, P = 0.005). Uncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends.

  15. Uncalibrated pulse power analysis fails to reliably measure cardiac output in patients undergoing coronary artery bypass surgery

    PubMed Central

    2011-01-01

    Introduction Uncalibrated arterial pulse power analysis has been recently introduced for continuous monitoring of cardiac index (CI). The aim of the present study was to compare the accuracy of arterial pulse power analysis with intermittent transpulmonary thermodilution (TPTD) before and after cardiopulmonary bypass (CPB). Methods Forty-two patients scheduled for elective coronary surgery were studied after induction of anaesthesia, before and after CPB respectively. Each patient was monitored with the pulse contour cardiac output (PiCCO) system, a central venous line and the recently introduced LiDCO monitoring system. Haemodynamic variables included measurement of CI derived by transpulmonary thermodilution (CITPTD) or CI derived by pulse power analysis (CIPP), before and after calibration (CIPPnon-cal., CIPPcal.). Percentage changes of CI (ΔCITPTD, ΔCIPPnon-cal./PPcal.) were calculated to analyse directional changes. Results Before CPB there was no significant correlation between CIPPnon-cal. and CITPTD (r2 = 0.04, P = 0.08) with a percentage error (PE) of 86%. Higher mean arterial pressure (MAP) values were significantly correlated with higher CIPPnon-cal. (r2 = 0.26, P < 0.0001). After CPB, CIPPcal. revealed a significant correlation compared with CITPTD (r2 = 0.77, P < 0.0001) with PE of 28%. Changes in CIPPcal. (ΔCIPPcal.) showed a correlation with changes in CITPTD (ΔCITPTD) only after CPB (r2 = 0.52, P = 0.005). Conclusions Uncalibrated pulse power analysis was significantly influenced by MAP and was not able to reliably measure CI compared with TPTD. Calibration improved accuracy, but pulse power analysis was still not consistently interchangeable with TPTD. Only calibrated pulse power analysis was able to reliably track haemodynamic changes and trends. PMID:21356060

  16. A novel method of measuring cardiac output in infants following extracorporeal procedures: preliminary validation in a swine model.

    PubMed

    Melchior, Richard; Darling, Edward; Terry, Bryan; Gunst, Gordy; Searles, Bruce

    2005-10-01

    In infants, technologies for obtaining rapid, quantified measurements of cardiac output (CO) following weaning from cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation are not readily available. A new technique to measure CO based on ultrasound velocity dilution is described. It utilizes reusable probes placed on the extracorporeal circuit that permits convenient measurement of CO prior to decannulation. This report provides preliminary validation data in an animal model. Three Yorkshire pigs (11-14 kg) were fully heparinized and cannulated via the right common carotid artery (cannula advanced to the aortic arch) and right atrium. Both the venous and arterial lines were instrumented with ultrasonic probes connected to a computer-monitoring system. A 'stopcock bridge' between the arterial and venous cannulas provided the access for saline injection and a controlled AV-shunt. For comparison, a vascular flow probe was fitted directly to the pulmonary artery (PA) in both animals and, for the larger animal, a PA catheter was inserted to obtain standard thermodilution measurements. Linear regression analysis revealed a correlation between the CO by ultrasound dilution (CO UD) technique and the vascular probe and PA thermodilution techniques to be R2 =0.94 and 0.81. This pilot study demonstrated that the CO UD technique correlates to other benchmarks of CO measurements. This novel technology has specific application in the field of pediatric open heart surgery in that it would allow the surgeon to accurately and inexpensively measure the CO of neonatal and pediatric patients before and after surgical manipulation of the heart without the need for placement of additional catheters or probes.

  17. [Validation during exercise of a new device for cardiac output measurement using pulse wave transit time (comparison EsCCO(®) vs. Physioflow(®))].

    PubMed

    Stalter, A; Lanot, N; Bridon, G; Julian, V; Péreira, B; Richard, R

    2016-02-01

    EsCCO is a novel non-invasive continuous cardiac output monitoring system based on pulse wave transit time already validated at rest. The aim of our study was to compare cardiac output measurements obtained simultaneously by EsCCO(®) (Q˙cOP) and impedance cardiography (Physioflow(®) ; Q˙cIMP), in healthy subjects. Eight healthy subjects (age: 31±9 years, weight: 76±10kg, height: 179±5cm) realized two exercise tests: an incremental ergocycle test performed until exertion (Pmax=269±48W) and a constant load exercise (P=163±27W). Comparison between measurements (Q˙cOP versus Q˙cIMP) obtained during the first test allowed to evaluate the accuracy of the device. Reliability was determined on three repeated measures during the second test, realized at ventilatory threshold. Correlation coefficient between both methods is 0.88 (P<0.01). Mean difference is 0.04±1.49L/min (95 % limits of agreement: +2.94 to -3.00L/min) and only 3/74 measures are not included between the limits of agreement. At high intensity and for cardiac output over than 15 L/min, Q˙cOP signal is lost in almost half the time. Concerning reliability, reproducibility coefficient is 0.87 (P<0.05), only 1.8 % of this variability is due to the method. EsCCO(®) measurements are accurate, reliable and allow a good estimation of cardiac output on healthy subjects. The signal lost observed for high cardiac output levels (>15L/min) can limit its utilization during very high intensity exercise. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  18. Lithium dilution, pulse power analysis, and continuous thermodilution cardiac output measurements compared with bolus thermodilution in anaesthetized ponies.

    PubMed

    Ambrisko, T D; Coppens, P; Kabes, R; Moens, Y

    2012-12-01

    This study compares cardiac output (CO) measurements obtained by lithium dilution (LiDCO), pulse power analysis (PulseCO), and continuous thermodilution (CTD) with bolus thermodilution (BTD) in ponies. Eight isoflurane-anaesthetized Shetland ponies received xylazine, ketamine, and midazolam infusions (0.3, 1.2, and 0.018 mg kg(-1) h(-1), respectively). CO was measured with BTD, CTD, LiDCO, and PulseCO. Lithium was injected into the jugular vein and blood was sampled from the facial artery for lithium detection and this artery was also used for PulseCO. Measurements were obtained during four stable haemodynamic conditions in the following order: isoflurane 1% (end-tidal concentration), isoflurane 2%, isoflurane 1%, and isoflurane 1%+dobutamine 5 µg kg(-1) min(-1). The bias (2 sd) was 2.5 (2.1) and 0.5 (2.9) litre min(-1) for LiDCO-BTD and for CTD-BTD comparisons, respectively. The limits of agreement were wider than ±30%; therefore, interchangeability was rejected for both comparisons. A possible error in LiDCO might explain the bias observed because CTD-BTD comparison showed less bias. Changes in PulseCO did not correlate with those of BTD and a weak correlation (r(2)=0.23; P=0.018) and concordance (Pc=0.42) was found between CTD and BTD. This is the first study to show a large bias for LiDCO-BTD comparison in animals receiving xylazine, ketamine, and midazolam infusions. The trending abilities of neither PulseCO nor CTD were reliable. Further studies are needed to elucidate possible influences of drugs on the accuracy of the LiDCOplus system.

  19. Addressing Assumptions for the Use of Non-invasive Cardiac Output Measurement Techniques During Exercise in COPD.

    PubMed

    Perrault, Hélène; Richard, Ruddy; Kapchinsky, Sophia; Baril, Jacinthe; Bourbeau, Jean; Taivassalo, Tanja

    2016-01-01

    The multifactorial functional limitation of COPD increasingly demonstrates the need for an integrated circulatory assessment. In this study cardiac output (Qc) derived from non-inert (CO2-RB), inert (N2O-RB) gas rebreathing approaches and bioimpedance were compared to examine the limitations of currently available non-invasive techniques for exercise Qc determination in patients with chronic lung disease. Thirteen COPD patients (GOLD II-III) completed three constant cycling bouts at 20, 35, and 50% of peak work on two occasions to assess Qc with bioimpedance as well as using CO2-RB and N2O-RB for all exercise tests. Results showed significantly lower Qc using the N2O-RB or end-tidal CO2-derived Qc compared to the PaCO2-derived CO2-RB or the bioimpedance at rest and for all exercise intensities. End-tidal CO2-derived values are however not statistically different from those obtained using inert-gas rebreathing. This study show that in COPD patients, CO2-rebreathing Qc values obtained using PaCO2 contents which account for any gas exchange impairment or inadequate gas mixing are similar to those obtained using thoracic bioimpedance. Alternately, the lower values for N2O rebreathing derived Qc indicates the inability of this technique to account for gas exchange impairment in the computation of Qc. These findings indicate that the choice of a gas rebreathing technique to measure Qc in patients must be dictated by the ability to include in the derived computations a correction for either gas exchange inadequacies and/or a vascular shunt.

  20. Validation of Noninvasive Measurement of Cardiac Output Using Inert Gas Rebreathing in a Cohort of Patients With Heart Failure and Reduced Ejection Fraction.

    PubMed

    Hassan, Mohamed; Wagdy, Kerolos; Kharabish, Ahmed; Selwanos, Peter Philip; Nabil, Ahmed; Elguindy, Ahmed; ElFaramawy, Amr; Elmahdy, Mahmoud F; Mahmoud, Hani; Yacoub, Magdi H

    2017-03-01

    Cardiac output (CO) is a key indicator of cardiac function in patients with heart failure. No completely accurate method is available for measuring CO in all patients. The objective of this study was to validate CO measurement using the inert gas rebreathing (IGR) method against other noninvasive and invasive methods of CO quantification in a cohort of patients with heart failure and reduced ejection fraction. The study included 97 patients with heart failure and reduced ejection fraction (age 42±15.5 years; 64 patients (65.9%) had idiopathic dilated cardiomyopathy and 21 patients (21.6%) had ischemic heart disease). Median left ventricle ejection fraction was 24% (10%-36%). Patients with atrial fibrillation were excluded. CO was measured using 4 methods (IGR, cardiac magnetic resonance imaging, cardiac catheterization, and echocardiography) and indexed to body surface area (cardiac index [CI]). All studies were performed within 48 hours. Median CI measured by IGR was 1.75, by cardiac magnetic resonance imaging was 1.82, by cardiac catheterization was 1.65, and by echo was 1.7 L·min(-1)·m(-2). There were significant modest linear correlations between IGR-derived CI and cardiac magnetic resonance imaging-derived CI (r=0.7; P<0.001), as well as cardiac catheterization-derived CI (r=0.6; P<0.001). Using Bland-Altman analysis, the agreement between the IGR method and the other methods was as good as the agreement between any 2 other methods with each other. The IGR method is a simple, accurate, and reproducible noninvasive method for quantification of CO in patients with advanced heart failure. The prognostic value of this simple measurement needs to be studied prospectively. © 2017 American Heart Association, Inc.

  1. Noninvasive monitoring of cardiac output during exercise by inductance cardiography.

    PubMed

    Kaplan, Vladimir; Bucklar, Guido B; Bloch, Konrad E

    2003-05-01

    Inductance cardiography is a noninvasive technique that monitors changes in cardiac output from an inductance plethysmographic transducer encircling the chest at the level of the heart. The method has been previously validated in supine patients at rest by comparisons to thermodilution. Our purpose was to investigate whether the technique can be employed during bicycle exercise. We simultaneously measured cardiac output by inductance cardiography and by two gas exchange methods based on the Fick principle during upright cycle ergometry in healthy volunteers. In 11 subjects, comparisons of changes in cardiac output by inductance cardiography agreed well with values measured by carbon dioxide rebreathing during a steady-state exercise protocol. In 12 subjects, cardiac output changes measured by inductance cardiography and an oxygen uptake method agreed closely during a progressive ramp exercise protocol to exhaustion. The bias (mean difference to reference methods) and limits of agreement (+/-2 SD of bias) for estimation of relative changes in cardiac output by inductance cardiography were 1% +/- 21% in 67 comparisons to the carbon dioxide rebreathing technique, and 0% +/- 22% in 98 comparisons to the oxygen uptake method. In healthy subjects, inductance cardiography accurately and unobtrusively estimates changes in cardiac output during bicycle exercise in comparison to gas exchange methods.

  2. Cardiac output changes during hyperbaric hyperoxia.

    PubMed

    Neubauer, B; Tetzlaff, K; Staschen, C M; Bettinghausen, E

    2001-03-01

    Increased ambient pressure and oxygen partial pressure (pO2) influence cardiovascular regulation during diving and caisson work. We measured the cardiac output (Q) in subjects who practiced moderate work at a usual diving depth of 30 m. In 23 healthy male Navy divers who performed steady state bicycle exercises (100 W workload) in a hyperbaric chamber Q was measured by a CO2-rebreathing technique at normal pressure (100 kPa) and at raised ambient pressure (400 kPa), in a random order. During the rebreathing maneuver the subjects were exposed to pO2 values which theoretically may have reached a maximum value of 87 kPa (normobaric) and 388 kPa (hyperbaric). During the experiments the ambient temperature ranged between 22 and 25 degrees C. There was a significant decrease of the directly measured Q, heart rate (HR) and the calculated stroke volume at depth when compared with normoxic and normobaric exercise. The decrease of Q amounted to 64% of the normobaric value (8.9 l min-1 versus 13.9 l min-1). The mean HR decreased from 104.7 min-1 (100 kPa) to 94.0 min-1 (400 kPa). The calculated mean stroke volume decreased from 133 ml (100 kPa) to 96 ml (400 kPa). During hyperoxic hyperbaria the peripheral vascular tonus increases due to the consecutively increased arterial oxygen content. The cardiac output may correlate to the peripheral vasoconstriction and is therefore indirectly influenced by elevation of inspiratory pO2 i.e. during the rebreathing maneuver.

  3. Importance of re-calibration time on pulse contour analysis agreement with thermodilution measurements of cardiac output: a retrospective analysis of intensive care unit patients.

    PubMed

    Scully, Christopher G; Gomatam, Shanti; Forrest, Shawn; Strauss, David G

    2016-10-01

    We assessed the effect of re-calibration time on cardiac output estimation and trending performance in a retrospective analysis of an intensive care unit patient population using error grid analyses. Paired thermodilution and arterial blood pressure waveform measurements (N = 2141) from 222 patient records were extracted from the Multiparameter Intelligent Monitoring in Intensive Care II database. Pulse contour analysis was performed by implementing a previously reported algorithm at calibration times of 1, 2, 8 and 24 h. Cardiac output estimation agreement was assessed using Bland-Altman and error grid analyses. Trending was assessed by concordance and a 4-Quadrant error grid analysis. Error between pulse contour and thermodilution increased with longer calibration times. Limits of agreement were -1.85 to 1.66 L/min for 1 h maximum calibration time compared to -2.70 to 2.41 L/min for 24 h. Error grid analysis resulted in 74.2 % of points bounded by 20 % error limits of thermodilution measurements for 1 h calibration time compared to 65 % for 24 h. 4-Quadrant error grid analysis showed <75 % of changes in pulse contour estimates to be within ±80 % of the change in the thermodilution measurement at any calibration time. Shorter calibration times improved the agreement of cardiac output pulse contour estimates with thermodilution. Use of minimally invasive pulse contour methods in intensive care monitoring could benefit from prospective studies evaluating calibration protocols. The applied pulse contour analysis method and thermodilution showed poor agreement to monitor changes in cardiac output.

  4. Cardiac output determinations with ear piece densitometry.

    PubMed

    Hedenstierna, G; Schildt, B

    1975-01-01

    The results of cardiac output determinations by a dye dilution technique were compared using (a) a dichromatic earpiece which was calibrated as a flow-through cuvette, but also permitted automatic computing by virtue of a pressure capsule, and (b) an ordinary flow-through densitometer. Eleven subjects, some with cardio-pulmonary disease, were investigated. Cardiac outputs were systematically overestimated when automatically computed. The results obtained by manual calculation with the ear-piece corresponded more nearly with those derived from the flow-through cuvette, but still with a deviation from the identity line and with a residual standard deviation of 0.8 l/min. Double determinations had a residual standard deviation of 0.7 l/min. Despite its ease of handling, an earpiece densitometer seems to be too unreliable to be suitable for routine use.

  5. Validation of cardiac output using real-time measurement of oxygen consumption during cardiac catheterization in children under 3 years of age.

    PubMed

    Seckeler, Michael D; Hirsch, Russel; Beekman, Robert H; Goldstein, Bryan H

    2014-01-01

    To validate a method for determination of cardiac index (CI) using real-time measurement of oxygen consumption (VO2 ) in young children undergoing cardiac catheterization. Retrospective review comparing thermodilution cardiac index (TDCI) to CI calculated by the Fick equation using real-time measured VO2 (RT-VO2 ) and VO2 derived from 2 published predictive equations. Paired t-test and Bland-Altman analysis were used to compare TDCI to Fick CI. A survey to ascertain pediatric cardiac catheterization practices regarding VO2 determination was also conducted. Quaternary care children's hospital cardiac catheterization laboratory. Children <3 years old with structurally normal hearts undergoing cardiac catheterization under general anesthesia with at least one set of contemporaneous TDCI and RT-VO2 measurements. Thirty-six paired measurements of TDCI and RT-VO2 were made in 27 patients over a 2-year period. Indications for catheterization included congenital diaphragmatic hernia postrepair (n = 13), heart disease post-orthotopic heart transplant (n = 13), and suspected cardiomyopathy (n = 1). Mean age was 21.5 ± 8 months; median weight was 9.9 kg (IQR 8.57, 12.2). RT-VO2 was higher than VO2 predicted by the LaFarge equation (190 ± 31 vs. 173.8 ± 12.8 mL/min/m(2), P < .001), but there was no difference between TDCI and Fick CI calculated using VO2 from any method. Bland-Altman analysis showed excellent agreement between TDCI and Fick CI using RT-VO2 and VO2 predicted by the Lundell equation; Fick CI using VO2 predicted by the LaFarge equation showed fair agreement with TDCI. In children <3 years with a structurally normal heart, RT-VO2 generates highly accurate determinations of Fick CI as compared with TDCI. Additionally, in this population, VO2 derived from the LaFarge and Lundell equations generates accurate Fick CI compared with TDCI. Future studies are needed to identify factors associated with inaccurate VO2 generated from these predictive equations. © 2013

  6. Impact of changes in systemic vascular resistance on a novel non-invasive continuous cardiac output measurement system based on pulse wave transit time: a report of two cases.

    PubMed

    Ishihara, Hironori; Tsutsui, Masato

    2014-08-01

    The inaccuracy of arterial waveform analysis for measuring continuos cardiac output (CCO) associated with changes in systemic vascular resistance (SVR) has been well documented. A new non-invasive continuous cardiac output monitoring system (esCCO) mainly utilizing pulse wave transit time (PWTT) in place of arterial waveform analysis has been developed. However, the trending ability of esCCO to measure cardiac output during changes in SVR remains unclear. After a previous multicenter study on esCCO measurement, we retrospectively identified two cases in which apparent changes in SVR developed in a short period during data collection. In each case, the trending ability of esCCO to measure cardiac output and time component of PWTT were analyzed. Recorded data suggest that the time component of PWTT may have a significant impact on the accuracy of estimating stroke volume during changes in SVR. However, further prospective clinical studies are required to test this hypothesis.

  7. Estimation of cardiac output and pulmonary vascular resistance by contrast echocardiography transit time measurement: a prospective pilot study.

    PubMed

    Choi, Brian G; Sanai, Reza; Yang, Benjamin; Young, Heather A; Mazhari, Ramesh; Reiner, Jonathan S; Lewis, Jannet F

    2014-10-31

    Studies with other imaging modalities have demonstrated a relationship between contrast transit and cardiac output (CO) and pulmonary vascular resistance (PVR). We tested the hypothesis that the transit time during contrast echocardiography could accurately estimate both CO and PVR compared to right heart catheterization (RHC). 27 patients scheduled for RHC had 2D-echocardiogram immediately prior to RHC. 3 ml of DEFINITY contrast followed by a 10 ml saline flush was injected, and a multi-cycle echo clip was acquired from the beginning of injection to opacification of the left ventricle. 2D-echo based calculations of CO and PVR along with the DEFINITY-based transit time calculations were subsequently correlated with the RHC-determined CO and PVR. The transit time from full opacification of the right ventricle to full opacification of the left ventricle inversely correlated with CO (r=-0.61, p<0.001). The transit time from peak opacification of the right ventricle to first appearance in the left ventricle moderately correlated with PVR (r=0.46, p<0.01). Previously described echocardiographic methods for the determination of CO (Huntsman method) and PVR (Abbas and Haddad methods) did not correlate with RHC-determined values (p = 0.20 for CO, p = 0.18 and p = 0.22 for PVR, respectively). The contrast transit time method demonstrated reliable intra- (p<0.0001) and inter-observer correlation (p<0.001). We describe a novel method for the quantification of CO and estimation of PVR using contrast echocardiography transit time. This technique adds to the methodologies used for noninvasive hemodynamic assessment, but requires further validation to determine overall applicability.

  8. Evaluation of noninvasive cardiac output methods during exercise

    NASA Technical Reports Server (NTRS)

    Moore, Alan D.; Barrows, Linda H.; Rashid, Michael; Siconolfi, Steven F.

    1992-01-01

    Noninvasive techniques to estimate cardiac output (Qc) will be used during future space flight. This retrospective literature survey compared the Qc techniques of carbon dioxide rebreathing (CO2-R), CO2 single breath (CO2-S), Doppler (DOP), impedance (IM), and inert gas (IG: acetylene or nitrous oxide) to direct (DIR) assessments measured at rest and during exercise.

  9. Pathophysiology of Post-Operative Low Cardiac Output Syndrome.

    PubMed

    Epting, Conrad L; McBride, Mary E; Wald, Eric L; Costello, John M

    2016-01-01

    Low cardiac output syndrome frequently complicates the post-operative care of infants and children following cardiac surgery. The onset of low cardiac output follows a predictable course in the hours following cardiopulmonary bypass, as myocardial performance declines in the face of an elevated demand for cardiac output. When demand outstrips supply, shock ensues, and early recognition and intervention can decrease mortality. Multifactorial in etiology, this article will discuss the pathophysiology of low cardiac output syndrome, including myocardial depression following bypass, altered cardiac loading conditions, and inflammation driving a hypermetabolic state. Contributions from altered neurohormonal, thyroid, and adrenal axes will also be discussed. Sources included the clinical experiences of four cardiac intensivists, supported throughout by primary sources and relevant reviews obtained through PubMed searches and from seminal textbooks in the field. This article addresses the second of eight topics comprising the special issue entitled "Pharmacologic strategies with afterload reduction in low cardiac output syndrome after pediatric cardiac surgery".

  10. Cardiac output response to exercise in chronic cardiac failure patients.

    PubMed

    Fukuda, Taira; Matsumoto, Akihiro; Kurano, Miwa; Takano, Haruhito; Iida, Haruko; Morita, Toshihiro; Yamashita, Hiroshi; Hirata, Yasunobu; Nagai, Ryozo; Nakajima, Toshiaki

    2012-01-01

    The purpose of this study was to investigate the precise pattern of stroke volume (SV) response during exercise in patients with chronic heart failure (CHF) compared with age-matched controls. Fourteen patients with CHF and 7 controls performed symptom-limited bicycle exercise testing with respiratory gas exchange measurement. Patients were classified into group A (n = 7) with peak VO2 ≥ 18.0 mL/kg/minute and group B (n = 7) with peak VO2 < 18.0 mL/kg/ minute. SV and cardiac output (CO) were continuously measured during exercise using a novel thoracic impedance method (Physioflow). CO and SV were lower in the group B patients than those in controls at peak exercise [CO: 11.3 ± 1.0 (SE) versus 15.6 ± 0.9 L/minute, P < 0.05, SV: 89 ± 6 versus 110 ± 6 mL, P < 0.05]. SV reached its peak levels during submaximal exercise and remained close to the peak value until peak exercise in 6 of 7 group B patients (86%). On the other hand, it progressively increased until peak exercise in 6 of 7 controls (86%) and 5 of 7 group A patients (71%). In all subjects, CO at peak exercise was more closely correlated with SV at peak exercise (r = 0.86, P < 0.001) than with peak heart rate (r = 0.69, P < 0.001). CHF patients with impaired exercise capacity had attenuated increment of CO during exercise, and SV reached its peak levels during submaximal exercise.

  11. Ease of noninvasive measurement of cardiac output coupled with peak VO2 determination at rest and during exercise in patients with heart failure.

    PubMed

    Lang, Chim C; Karlin, Paula; Haythe, Jennifer; Tsao, Lana; Mancini, Donna M

    2007-02-01

    Peak oxygen consumption (VO2) is a powerful prognostic predictor of survival in patients with heart failure (HF) because it provides an indirect assessment of a patient's ability to increase cardiac output (CO). However, many peripheral factors affect VO2. Inert gas rebreathing using low-concentration soluble and insoluble inert gases can derive CO by the Fick principle. The Innocor rebreathing system uses an oxygen-enriched mixture of an inert soluble gas (0.5% nitrous oxide) and an inert insoluble gas (0.1% sulfur hexafluoride) measured by photoacoustic analyzers over a 5-breath interval. The practicality of this device in measuring CO and VO2 during exercise was assessed in patients with HF. Ninety-two consecutive exercise tests were prospectively performed in 88 patients with HF using the Innocor system. Incremental bicycle exercise was performed with CO measurements at rest, at 50 W, and at peak exercise. The mean age of the 68 men and 20 women was 54 +/- 13 years; 33% had coronary artery disease, and 67% had dilated cardiomyopathy. The mean left ventricular ejection fraction was 24 +/- 9%. Patients were able to rapidly learn the rebreathing technique and easily integrate it into the exercise protocol. Eighty-six percent of the tests had successful measurement of metabolic and cardiac output data. Mean CO at rest was 3.5 +/- 1.1 L/min and increased to 7.2 +/- 2.7 L/min. Mean peak VO2 was 12.6 +/- 4.7 ml/kg/min. A significant linear correlation was observed between peak VO2 and peak CO (r = 0.64, p <0.0001). In conclusion, combined metabolic stress testing with inert gas rebreathing can be easily performed in patients with HF.

  12. Less-invasive cardiac output monitoring by earpiece densitometry.

    PubMed

    Grasberger, R C; Yeston, N S

    1986-06-01

    Cardiac output was measured by thermodilution and ear densitometry in surgical ICU patients who had pulmonary arterial catheters. Overall comparison based on 56 sets of triplicate measurements revealed a correlation coefficient (r) of 0.76 between the two techniques. Although ear densitometry was more accurate with injection via the antecubital vein (r = 0.88) vs. more distal injection (r = 0.67), these data suggest that this technique lacks the accuracy for clinical application.

  13. The Impact of Direct Cardiac Output Determination On Using A Widely Available Direct Continuous Oxygen Consumption Measuring Device On The Hemodynamic Assessment of Aortic Valve

    PubMed Central

    Fanari, Zaher; Grove, Matthew; Rajamanickam, Anitha; Hammami, Sumaya; Walls, Cassie; Kolm, Paul; Saltzberg, Mitchell; Weintraub, William S.; Doorey, Andrew J.

    2016-01-01

    Background Accurate assessment of cardiac output (CO) is essential for the hemodynamic assessment of aortic valve area (AVA). Estimation of oxygen consumption (VO2) and Thermodilution (TD) is employed in many cardiac catheterization laboratories (CCL) given the historically cumbersome nature of direct continuous VO2 measurement, the “gold standard” for this technique. A portable facemask device simplifies the direct continuous measurement of VO2, allowing for relatively rapid and continuous assessment of CO and AVA. Methods and Materials Seventeen consecutive patients undergoing right heart catheterization had simultaneous determination of CO by both direct continuous and assumed VO2 and TD. Assessments were only made when a plateau of VO2 had occurred. All measurements of direct continuous and assumed VO2, as well as, TD CO were obtained in triplicate. Results Direct continuous VO2 CO and assumed VO2 CO correlated poorly (R= 0.57; ICC =0.59). Direct continuous VO2 CO and TD CO also correlated poorly (R= 0.51; ICC=0.60). Similarly AVA derived from direct continuous VO2 correlated poorly with those of assumed VO2 (R= 0.68; ICC=0.55) and TD (R=0.66, ICC=0.60). Repeated direct continuous VO2 CO and AVA measurements were extremely correlated and reproducible [(R=0.93; ICC=0.96) and (R=0.99; ICC>0.99) respectively], suggesting that this was the most reliable measurement of CO. Conclusions CO calculated from direct continuous VO2 measurement varies substantially from both assumed VO2 and TD based CO, which are widely used in most CCL. These differences may significantly impact the CO and AVA measurements. Furthermore, continuous, rather than average, measurement of VO2 appears to give highly reproducible results. PMID:27904163

  14. Non-invasive assessment of cardiac output in children.

    PubMed Central

    Richardson, J R; Ferguson, J; Hiscox, J; Rawles, J

    1998-01-01

    BACKGROUND: Stroke distance, the systolic velocity integral of aortic blood flow, is a linear analogue of stroke volume; its product with heart rate is minute distance, analogous to cardiac output. OBJECTIVE: To investigate the feasibility of assessing cardiac output in children with a simple non-invasive Doppler ultrasound technique, and to determine the normal range of values. METHODS: Peak aortic blood velocity, stroke distance, and minute distance were measured through the suprasternal window in 166 children (mean age 9.6 years, range 2-14) using a portable non-imaging Doppler ultrasound instrument. RESULTS: The technique was well tolerated by all the children participating. Mean peak aortic blood velocity was 138 cm/s and was independent of age. Mean stroke distance was 31.8 cm and showed a small but significant increase with age; mean minute distance was 2490 cm and fell with age, as did heart rate. CONCLUSIONS: Suprasternal Doppler ultrasound measurement of stroke distance is a convenient, well tolerated, non-invasive technique for the assessment of cardiac output in children. The normal range of values during childhood has been established. The technique has great potential for assessing hypovolaemia in children. Images p307-a PMID:9785155

  15. Comparison of stroke volume and cardiac output as measured by a single observer using four different ultrasound techniques in six clinically healthy cats.

    PubMed

    Biermann, K; Hungerbühler, S; Kästner, S B R

    2012-12-01

    The aim of this study was to assess agreement and repeatability of four ultrasound methods for measuring stroke volume (SV) and cardiac output (CO) in cats. Measurement of SV and CO was performed by the Teichholz method, the Simpson's method (SM), the area length method (ALM) and a volumetric flow method across the aorta (Trace method). For each method, the coefficient of variation (CV) was calculated and agreement was determined by Bland-Altman analysis. The CV was acceptable (<20%) for all parameters, except for SV and CO obtained by SM (28.8% and 22.4%, respectively) and ALM (21.6% and 22.6%, respectively). Narrow limits of agreement were observed between both planimetric methods (SM and ALM). The Trace method was the most repeatable, followed by the Teichholz method. Despite excellent inter-method agreement, neither of the planimetric methods produced results with adequate repeatability. As the Teichholz and Trace methods were acceptably repeatable, and probably gave the most representative values, they appear to be the most useful methods for the measurement of SV and CO in cats. Further investigations are needed to compare the echocardiographic methods described here with a standard technique such as thermodilution.

  16. The impact of phenylephrine, ephedrine, and increased preload on third-generation Vigileo-FloTrac and esophageal doppler cardiac output measurements.

    PubMed

    Meng, Lingzhong; Tran, Nam Phuong; Alexander, Brenton S; Laning, Kathleen; Chen, Guo; Kain, Zeev N; Cannesson, Maxime

    2011-10-01

    Cardiac output (CO) monitoring based on pulse contour analysis (Vigileo-FloTrac) has the potential to be used for goal-directed fluid therapy in the perioperative setting. However, factors such as vasopressor usage may impact Vigileo-FloTrac's reliability in tracking CO changes. We tested third-generation Vigileo-FloTrac system's ability to accurately measure the changes in CO induced by vasopressor administration and increased preload in comparison with esophageal Doppler measurements. In 33 anesthetized patients, CO was monitored simultaneously by the third-generation Vigileo-FloTrac and esophageal Doppler. Hemodynamic challenges included phenylephrine (to increase vasomotor tone), ephedrine (to increase myocardial contractility and heart rate), and whole-body tilting (to increase preload). Measurements were performed before and after each intervention. Overall, 176 pairs of CO measurements were obtained. The difference between paired pulse contour and Doppler measurements of CO was 0.14 ± 2.13 L/min (mean ± SD), and the percentage error (2 SD of the difference divided by the mean CO of the reference method) was 66%. The trending ability of pulse contour versus Doppler was 23% (concordance, the percentage of the total number of data points that are in 1 of the 2 quadrants of agreement) after phenylephrine treatment, 69% (concordance) after ephedrine treatment, and 96% (concordance) after whole-body tilting. The pulse contour method of measuring CO, as implemented in the third-generation Vigileo-FloTrac device, accurately tracks changes in CO when preload changes. However, the pulse contour method does not accurately track changes in CO induced with phenylephrine and ephedrine.

  17. Estimation of cardiac output and systemic vascular resistance using a multivariate regression model with features selected from the finger photoplethysmogram and routine cardiovascular measurements

    PubMed Central

    2013-01-01

    Background Cardiac output (CO) and systemic vascular resistance (SVR) are two important parameters of the cardiovascular system. The ability to measure these parameters continuously and noninvasively may assist in diagnosing and monitoring patients with suspected cardiovascular diseases, or other critical illnesses. In this study, a method is proposed to estimate both the CO and SVR of a heterogeneous cohort of intensive care unit patients (N=48). Methods Spectral and morphological features were extracted from the finger photoplethysmogram, and added to heart rate and mean arterial pressure as input features to a multivariate regression model to estimate CO and SVR. A stepwise feature search algorithm was employed to select statistically significant features. Leave-one-out cross validation was used to assess the generalized model performance. The degree of agreement between the estimation method and the gold standard was assessed using Bland-Altman analysis. Results The Bland-Altman bias ±precision (1.96 times standard deviation) for CO was -0.01 ±2.70 L min-1 when only photoplethysmogram (PPG) features were used, and for SVR was -0.87 ±412 dyn.s.cm-5 when only one PPG variability feature was used. Conclusions These promising results indicate the feasibility of using the method described as a non-invasive preliminary diagnostic tool in supervised or unsupervised clinical settings. PMID:23452705

  18. Usefulness of non-invasive measurement of cardiac output during sub-maximal exercise to predict outcome in patients with chronic heart failure.

    PubMed

    Goda, Ayumi; Lang, Chim C; Williams, Paula; Jones, Margaret; Farr, Mary Jane; Mancini, Donna M

    2009-12-01

    Peak oxygen consumption (Vo(2)) is a powerful prognostic predictor of survival in patients with chronic heart failure (CHF) because it provides an indirect assessment of a patient's ability to increase cardiac output (CO). However, many patients with CHF who undergo cardiopulmonary exercise testing are unable to perform maximal exercise. New metabolic carts coupled with the inert gas rebreathing technique provide a noninvasive measurement of CO. Whether the noninvasive measurement of CO at a fixed submaximal workload can predict outcome is unknown. This study's population comprised 259 patients (mean age 54 +/- 14 years, mean left ventricular ejection fraction 27 +/- 14%) with CHF who underwent symptom-limited incremental cardiopulmonary exercise testing. Vo(2) and CO were measured at rest, at 25 W, and at peak exercise. Submaximal exercise was defined as <80% peak Vo(2). Among 259 patients, 145 had Vo(2) at 25 W <80% of peak. Vo(2) at 25 W averaged 9.3 +/- 1.8 ml/kg/min. This Vo(2) represented 62 +/- 11% of peak Vo(2), which averaged 15.4 +/- 4.4 ml/kg/min. Prospective follow-up averaged 521 +/- 337 days. In this cohort, there were 15 outcome events (death, urgent heart transplantation, or implantation of a left ventricular assist device as a bridge to transplantation). On univariate Cox hazard analysis, CO at 25 W (hazard ratio 0.64, 95% confidence interval 0.48 to 0.84, p = 0.002) was found to be significant predictor of events of outcome. In conclusion, CO at 25 W measured noninvasively during submaximal exercise may have potential value as a predictor of outcomes in patients with CHF.

  19. A fiberoptic reflection densitometer with cardiac output calculator.

    PubMed

    Landsman, M L; Knop, N; Mook, G A; Zijlstra, W G

    1979-02-14

    A catheter-tip densitometer for indocyanine green is described consisting of a cardiac catheter containing optical fibers, an 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 back-scattered (reflected) light to the detection unit. In the detection unit the light is measured by two silicium barrier layer photocells after it has been split into two beams by a beam splitter. In the measuring channel the light passes an 800 nm filter before reaching the photocell. When fiberoptic catheters with glass fibers are employed, the other channel, used for compensation of non-specific effects such as blood flow variations, contains no filter, thus measuring light in a broad spectral band. It is shown that in this way compensation of flow effects may be about two times better than when a 920 nm filter is used. When using plastic optical fibers a 950 nm filter must be used, because above lambda = 850 nm plastic fibers transmit only a band around that wavelength (950 nm). At zero dye concentration the densitometer output or ratio of compensating and measuring photocell output R/R800 is almost insensitive to changes in haemoglobin concentration. When the blood contains dye, however, the influence of haemoglobin concentration is considerable. The densitometer output R/R800 is linearly related to dye concentration up to 50 mg . 1-1, the output R920/R800 up to 30 mg . 1(-1). The output R/R800 decreases with decreasing oxygen saturation; the slope of the calibration line, however, appears to be unaffected. The processing unit also contains an analog cardiac output calculator consisting of an integrator and a divider. Central dye dilution curves recorded from the pulmonary artery after injection of dye into the right atrium or a caval vein come down to the baseline. At this moment the reading of a digital voltmeter displaying the divider output calibrated in 1

  20. Reproducibility of cardiac power output and other cardiopulmonary exercise indices in patients with chronic heart failure.

    PubMed

    Jakovljevic, Djordje G; Seferovic, Petar M; Nunan, David; Donovan, Gay; Trenell, Michael I; Grocott-Mason, Richard; Brodie, David A

    2012-02-01

    Cardiac power output is a direct measure of overall cardiac function that integrates both flow- and pressure-generating capacities of the heart. The present study assessed the reproducibility of cardiac power output and other more commonly reported cardiopulmonary exercise variables in patients with chronic heart failure. Metabolic, ventilatory and non-invasive (inert gas re-breathing) central haemodynamic measurements were undertaken at rest and near-maximal exercise of the modified Bruce protocol in 19 patients with stable chronic heart failure. The same procedure was repeated 7 days later to assess reproducibility. Cardiac power output was calculated as the product of cardiac output and mean arterial pressure. Resting central haemodynamic variables demonstrate low CV (coefficient of variation) (ranging from 3.4% for cardiac output and 5.6% for heart rate). The CV for resting metabolic and ventilatory measurements ranged from 8.2% for respiratory exchange ratio and 14.2% for absolute values of oxygen consumption. The CV of anaerobic threshold, peak oxygen consumption, carbon dioxide production and respiratory exchange ratio ranged from 3.8% (for anaerobic threshold) to 6.4% (for relative peak oxygen consumption), with minute ventilation having a CV of 11.1%. Near-maximal exercise cardiac power output and cardiac output had CVs of 4.1 and 2.2%, respectively. Cardiac power output demonstrates good reproducibility suggesting that there is no need for performing more than one cardiopulmonary exercise test. As a direct measure of cardiac function (dysfunction) and an excellent prognostic marker, it is strongly advised in the assessment of patients with chronic heart failure undergoing cardiopulmonary exercise testing.

  1. Assessment of cardiac output changes using a modified FloTrac/Vigileo algorithm in cardiac surgery patients.

    PubMed

    Senn, Alban; Button, Danny; Zollinger, Andreas; Hofer, Christoph K

    2009-01-01

    The FloTrac/Vigileo (Edwards Lifesciences, Irvine, CA, USA) allows pulse pressure-derived cardiac output measurement without external calibration. Software modifications were performed in order to eliminate initially observed deficits. The aim of this study was to assess changes in cardiac output determined by the FloTrac/Vigileo system (FCO) with an initially released (FCOA) and a modified (FCOB) software version, as well as changes in cardiac output from the PiCCOplus system (PCO; Pulsion Medical Systems, Munich, Germany). Both devices were compared with cardiac output measured by intermittent thermodilution (ICO). Cardiac output measurements were performed in patients after elective cardiac surgery. Two sets of data (A and B) were obtained using FCOA and FCOB in 50 patients. After calibration of the PiCCOplus system, triplicate FCO and PCO values were recorded and ICO was determined in the supine position and cardiac output changes due to body positioning were recorded 15 minutes later (30 degrees head-up, 30 degrees head-down, supine). Student's t test, analysis of variance and Bland-Altman analysis were calculated. Significant changes of FCO, PCO and ICO induced by body positioning were observed in both data sets. For set A, DeltaFCOA was significantly larger than DeltaICO induced by positioning the head down. For set B, there were no significant differences between DeltaFCOB and DeltaICO. For set A, increased limits of agreement were found for FCOA-ICO when compared with PCO-ICO. For set B, mean bias and limits of agreement were comparable for FCOB-ICO and PCO-ICO. The modification of the FloTrac/Vigileo system resulted in an improved performance in order to reliably assess cardiac output and track the related changes in patients after cardiac surgery.

  2. The influence of acute pulmonary hypertension on cardiac output measurements: calibrated pulse contour analysis, transpulmonary and pulmonary artery thermodilution against a modified Fick method in an animal model.

    PubMed

    Kutter, Annette P N; Mosing, Martina; Hartnack, Sonja; Raszplewicz, Joanna; Renggli, Martina; Mauch, Jacqueline Y; Hofer, Christoph K

    2015-07-01

    In critically ill patients with significant pulmonary hypertension (PH), close perioperative cardiovascular monitoring is mandatory, considering the increased morbidity and mortality in this patient group. Although the pulmonary artery catheter is still the standard for the diagnosis of PH, its use to monitor cardiac output (CO) in patients with PH is decreasing as a result of increased morbidity and possible influence of tricuspid regurgitation on the measurements. However, continuous CO measurement methods have never been evaluated under PH regarding their agreement and trending ability. In this study, we evaluated the influence of acute PH and different CO states on transpulmonary thermodilution (TPTD) and calibrated pulse contour analysis (PiCCO; both assessed with PiCCO plus™), intermittent pulmonary artery thermodilution (PATD), and continuous thermodilution (CCO) compared with a modified Fick method (FICK) in an animal model. Nine healthy pigs were studied under anesthesia. PH of 25 and 40 mm Hg (by administration of the thromboxane analog U46619), CO decreases, and CO increases were induced to test the different CO measurement techniques over a broad range of hemodynamic situations. Before each step, a new baseline data set was collected. CO values were compared using Bland-Altman analysis; trending abilities were assessed via concordance and polar plot analysis. The influence of pulmonary pressure on CO measurements was analyzed using linear mixed models. A mean bias of -0.26 L/min with prediction intervals of -0.88 to 1.4 L/min was measured between TPTD and FICK. Their concordance rate was 100% (94%-100% confidence interval), and the mean polar angle -3° with radial limits of agreement of ±28° indicated good trending abilities. PATD compared with FICK also showed good trending ability. Comparisons of PiCCO and CCO versus FICK revealed low agreement and poor trending results with concordance rates of 84% (71%-93%) and 88% (74%-95%), mean polar angles

  3. Use of the single-breath method of estimating cardiac output during exercise-stress testing.

    NASA Technical Reports Server (NTRS)

    Buderer, M. C.; Rummel, J. A.; Sawin, C. F.; Mauldin, D. G.

    1973-01-01

    The single-breath cardiac output measurement technique of Kim et al. (1966) has been modified for use in obtaining cardiac output measurements during exercise-stress tests on Apollo astronauts. The modifications involve the use of a respiratory mass spectrometer for data acquisition and a digital computer program for data analysis. The variation of the modified method for triplicate steady-state cardiac output measurements was plus or minus 1 liter/min. The combined physiological and methodological variation seen during a set of three exercise tests on a series of subjects was 1 to 2.5 liter/min. Comparison of the modified method with the direct Fick technique showed that although the single-breath values were consistently low, the scatter of data was small and the correlation between the two methods was high. Possible reasons for the low single-breath cardiac output values are discussed.

  4. Non-invasive determination of cardiac output by Doppler echocardiography and electrical bioimpedance.

    PubMed Central

    Northridge, D B; Findlay, I N; Wilson, J; Henderson, E; Dargie, H J

    1990-01-01

    Cardiac output measured by thermodilution in 25 patients within 24 hours of acute myocardial infarction was compared with cardiac output measured by Doppler echocardiography (24 patients) and electrical bioimpedance (25 patients). The mean (range) cardiac outputs measured by Doppler (4.03 (2.2-6.0) 1/min) and electrical bioimpedance (3.79 (1.1-6.2) 1/min) were similar to the mean thermodilution value (3.95 (2.1-6.2) 1/min). Both non-invasive techniques agreed closely with thermodilution in most patients. None the less, three results with each method disagreed with thermodilution by more than 1 1/min. Both non-invasive techniques were reproducible and accurate in most patients with acute myocardial infarction. Doppler echocardiography was time consuming and technically demanding. Electrical bioimpedance was simple to use and had the additional advantage of allowing continuous monitoring of the cardiac output. PMID:2317415

  5. Use of the single-breath method of estimating cardiac output during exercise-stress testing.

    NASA Technical Reports Server (NTRS)

    Buderer, M. C.; Rummel, J. A.; Sawin, C. F.; Mauldin, D. G.

    1973-01-01

    The single-breath cardiac output measurement technique of Kim et al. (1966) has been modified for use in obtaining cardiac output measurements during exercise-stress tests on Apollo astronauts. The modifications involve the use of a respiratory mass spectrometer for data acquisition and a digital computer program for data analysis. The variation of the modified method for triplicate steady-state cardiac output measurements was plus or minus 1 liter/min. The combined physiological and methodological variation seen during a set of three exercise tests on a series of subjects was 1 to 2.5 liter/min. Comparison of the modified method with the direct Fick technique showed that although the single-breath values were consistently low, the scatter of data was small and the correlation between the two methods was high. Possible reasons for the low single-breath cardiac output values are discussed.

  6. Validation of the qCO cardiac output monitor during Valsalva maneuver.

    PubMed

    Jospin, Mathieu; Aguilar, Juan P; Gambus, Pedro L; Jensen, Erik W; Vallverdu, Montserrat; Caminal, Pere

    2012-01-01

    Monitoring cardiac output for a variety of patient conditions is essential to ensure tissue perfusion and oxygenation. Cardiac output can be measured either invasively using a pulmonary artery catheter or non-invasively using impedance cardiography (ICG). The objective of the present study was to validate a cardiac output monitor, the qCO (Quantium Medical, Barcelona, Spain). The qCO is based on the ICG principle. Twenty-five volunteers (18-75 years) were enrolled in the study. The duration of the study was 10 min. The subjects were asked to rest quietly in an armchair for a duration of 5 min. At 5 min they were asked to do a Valsalva maneuver which is known to decrease the cardiac output. The baseline value of the normalized cardiac output (qCO index) was compared with the minimum value during the Valsalva maneuver. The results showed (t-test, p<0.0005) significant difference between the cardiac output estimated at baseline and during the Valsalva maneuver. In conclusion, the qCO was able to indicate trend changes of the cardiac output in volunteers.

  7. Comparison of three methods for cardiac output determination in cats.

    PubMed

    Dyson, D H; Allen, D G; McDonell, W N

    1985-12-01

    Cardiac output (CO) was measured in sodium pentobarbital-anesthetized cats over a wide range of blood flow rates. In 10 cats, CO was measured simultaneously, using Fick determination and thermodilution techniques. Echocardiography was used to estimate contractility of the heart by measuring percentage change in minor diameter and velocity of circumferential fiber shortening. These indices were compared with CO by the other techniques. Echocardiographic equations used for CO determination in man were evaluated for reliability in the cat. Thermodilution and Fick determination correlated best with low CO (r = 0.89) and less with intermediate (r = 0.69) and high (r = 0.75) CO. Percentage change in minor diameter and velocity of circumferential fiber shortening correlated with thermodilution measurements of the cardiac index (r = 0.71 and r = 0.84, respectively). The value of echocardiography for CO estimation was questionable, using existing equations. Fick determination of CO was more inconsistent and was more prone to technical error than was thermodilution.

  8. Cardiac output estimation using pulmonary mechanics in mechanically ventilated patients

    PubMed Central

    2010-01-01

    The application of positive end expiratory pressure (PEEP) in mechanically ventilated (MV) patients with acute respiratory distress syndrome (ARDS) decreases cardiac output (CO). Accurate measurement of CO is highly invasive and is not ideal for all MV critically ill patients. However, the link between the PEEP used in MV, and CO provides an opportunity to assess CO via MV therapy and other existing measurements, creating a CO measure without further invasiveness. This paper examines combining models of diffusion resistance and lung mechanics, to help predict CO changes due to PEEP. The CO estimator uses an initial measurement of pulmonary shunt, and estimations of shunt changes due to PEEP to predict CO at different levels of PEEP. Inputs to the cardiac model are the PV loops from the ventilator, as well as the oxygen saturation values using known respiratory inspired oxygen content. The outputs are estimates of pulmonary shunt and CO changes due to changes in applied PEEP. Data from two published studies are used to assess and initially validate this model. The model shows the effect on oxygenation due to decreased CO and decreased shunt, resulting from increased PEEP. It concludes that there is a trade off on oxygenation parameters. More clinically importantly, the model also examines how the rate of CO drop with increased PEEP can be used as a method to determine optimal PEEP, which may be used to optimise MV therapy with respect to the gas exchange achieved, as well as accounting for the impact on the cardiovascular system and its management. PMID:21108836

  9. Comparison of cardiac output determined by bioimpedance and bioreactance methods at rest and during exercise.

    PubMed

    Jakovljevic, Djordje G; Moore, Sarah; Hallsworth, Kate; Fattakhova, Gulnar; Thoma, Christian; Trenell, Michael I

    2012-04-01

    Bioreactance is a novel non-invasive method for cardiac output measurement that involves the analysis of blood flow-dependent changes in the phase shifts of electrical currents applied across the chest. The present study (1) compared resting and exercise cardiac outputs determined by bioreactance and bioimpedance methods and those estimated from measured oxygen consumption, (2) determined the relationship between cardiac output and oxygen consumption, and (3) assessed the agreement between the bioreactance and bioimpedance methods. Twelve healthy subjects (aged 30 ± 4 years) performed graded cardiopulmonary exercise test on a recumbent cycle ergometer on two occasions, 1 week apart. Cardiac output was monitored at rest, at 30, 50, 70, 90, 150 W and at peak exercise intensity by bioreactance and bioimpedance and expired gases collected. Resting cardiac output was not significantly different between the bioreactance and bioimpedance methods (6.2 ± 1.4 vs. 6.5 ± 1.4 l min(-1), P = 0.42). During exercise cardiac outputs were correlated with oxygen uptake for both bioreactance (r = 0.84, P < 0.01) and bioimpedance techniques (r = 0.82, P < 0.01). At peak exercise bioimpedance estimated significantly lower cardiac outputs than both bioreactance and theoretically calculated cardiac output (14.3 ± 2.6 vs. 17.5 ± 5.2 vs. 16.9 ± 4.9 l min(-1), P < 0.05). Bland-Altman analyses including data from rest and exercise demonstrated that the bioimpedance method reported ~1.5 l min(-1) lower cardiac output than bioreactance with lower and upper limits of agreement of -2.98 to 5.98 l min(-1). Bioimpedance and bioreactance methods provide different cardiac output estimates, particularly at high exercise intensity, and therefore the two methods cannot be used interchangeably. In contrast with bioimpedance, bioreactance cardiac outputs are similar to those estimated from measured oxygen consumption.

  10. Pulse transit time measured by photoplethysmography improves the accuracy of heart rate as a surrogate measure of cardiac output, stroke volume and oxygen uptake in response to graded exercise.

    PubMed

    Pollonini, L; Padhye, N S; Re, R; Torricelli, A; Simpson, R J; Dacso, C C

    2015-05-01

    Heart rate (HR) is a valuable and widespread measure for physical training programs, although its description of conditioning is limited to the cardiac response to exercise. More comprehensive measures of exercise adaptation include cardiac output (Q̇), stroke volume (SV) and oxygen uptake (V̇O2), but these physiological parameters can be measured only with cumbersome equipment installed in clinical settings. In this work, we explore the ability of pulse transit time (PTT) to represent a valuable pairing with HR for indirectly estimating Q̇, SV and V̇O2 non-invasively. PTT was measured as the time interval between the peak of the electrocardiographic (ECG) R-wave and the onset of the photoplethysmography (PPG) waveform at the periphery (i.e. fingertip) with a portable sensor. Fifteen healthy young subjects underwent a graded incremental cycling protocol after which HR and PTT were correlated with Q̇, SV and V̇O2 using linear mixed models. The addition of PTT significantly improved the modeling of Q̇, SV and V̇O2 at the individual level ([Formula: see text] for SV, 0.548 for Q̇, and 0.771 for V̇O2) compared to predictive models based solely on HR ([Formula: see text] for SV, 0.503 for Q̇, and 0.745 for V̇O2). While challenges in sensitivity and artifact rejection exist, combining PTT with HR holds potential for development of novel wearable sensors that provide exercise assessment largely superior to HR monitors.

  11. Metabolic regulation of cardiac output during inhalation anaesthesia in dogs.

    PubMed

    Scheeren, T W; Schwarte, L A; Arndt, J O

    1999-04-01

    The metabolic regulation of tissue blood flow manifests itself in a linear relation between blood flow and oxygen consumption, the latter being the independent variable. It is unknown, however, if this fundamental physiological principle operates also during inhalation anaesthesia known to be associated with decreases in both cardiac output (Q) and oxygen consumption (VO2). Seven dogs (23-32 kg) with chronically implanted flow probes around the pulmonary artery were repeatedly anaesthetized with halothane, enflurane, isoflurane, sevoflurane, and desflurane at increasing minimum alveolar concentrations (1-3 MAC). Cardiac output (ultrasound transit-time flowmeter) and VO2 (indirect calorimetry) were measured continuously. We also imposed selective changes in Q, and thus of O2 supply, to see if and to what extent this would alter VO2 during anaesthesia (1.5 MAC). In awake dogs under basal metabolic conditions, VO2 was 4.6 +/- 0.1 ml.kg-1.min-1 and Q 105 +/- 3 ml.kg-1.min-1 (mean +/- SEM). During inhalation anaesthesia, VO2 and Q decreased by approximately 30% and 60%, respectively. The concentration-effect relations of both variables did not differ between anaesthetics, yielding a uniform Q/VO2 relation, which was nearly linear in the range (0-2 MAC) with an average slope of 39 +/- 1 (range 30-55). Above 2 MAC, Q decreased more for a given change in VO2, and O2 extraction increased by 50%, indicating compromised oxygen delivery (DO2). Imposed changes in Q, both in awake and anaesthetized dogs, yielded Q/VO2 relations which were notably steeper (slopes 114 to 187) than those observed during inhalation anaesthesia. More important, imposed increases in Q and thus DO2 during anaesthesia (1.5 MAC) to rates comparable to that in the awake state produced a much less than proportional increase in VO2 without restoring it to baseline. Inhalation anaesthesia is characterized by a uniform Q/VO2 relation with an almost linear course at an anaesthetic concentration up to 2 MAC

  12. Evaluation of cardiac output by 5 arterial pulse contour techniques using trend interchangeability method

    PubMed Central

    Fischer, Marc-Olivier; Diouf, Momar; de Wilde, Robert B.P.; Dupont, Hervé; Hanouz, Jean-Luc; Lorne, Emmanuel

    2016-01-01

    Abstract Cardiac output measurement with pulse contour analysis is a continuous, mini-invasive, operator-independent, widely used, and cost-effective technique, which could be helpful to assess changes in cardiac output. The 4-quadrant plot and the polar plot have been described to compare the changes between 2 measurements performed under different conditions, and the direction of change by using different methods of measurements. However, the 4-quadrant plot and the polar plot present a number of limitations, with a risk of misinterpretation in routine clinical practice. We describe a new trend interchangeability method designed to objectively define the interchangeability of each change of a variable. Using the repeatability of the reference method, we classified each change as either uninterpretable or interpretable and then as either noninterchangeable, in the gray zone or interchangeable. An interchangeability rate can then be calculated by the number of interchangeable changes divided by the total number of interpretable changes. In this observational study, we used this objective method to assess cardiac output changes with 5 arterial pulse contour techniques (Wesseling's method, LiDCO, PiCCO, Hemac method, and Modelflow) in comparison with bolus thermodilution technique as reference method in 24 cardiac surgery patients. A total of 172 cardiac output variations were available from the 199 data points: 88 (51%) were uninterpretable, according to the first step of the method. The second step of the method, based on the 84 (49%) interpretable variations, showed that only 18 (21%) to 30 (36%) variations were interchangeable regardless of the technique used. None of pulse contour cardiac output technique could be interchangeable with bolus thermodilution to assess changes in cardiac output using the trend interchangeability method in cardiac surgery patients. Future studies may consider using this method to assess interchangeability of changes between different

  13. Instantaneous and continuous cardiac output in humans obtained with a Doppler pulmonary artery catheter.

    PubMed

    Segal, J; Nassi, M; Ford, A J; Schuenemeyer, T D

    1990-11-01

    A new Doppler pulmonary artery catheter was used to measure instantaneous and continuous cardiac output in both an in vitro model and in 44 patients undergoing cardiac catheterization. Cardiac output was calculated with use of the Doppler catheter-determined instantaneous space-average velocity and the ultrasonically determined instantaneous vessel area. Doppler flow and thermodilution were compared with electromagnetic flow in the in vitro model and with Fick cardiac output in patients. Doppler catheter-determined flow was highly predictive of electro-magnetic flow in the pulsatile flow model (r = 0.99, slope [m] = 1.01 and SEE = 0.05) and appeared comparable to thermodilution measurements (r = 1.00, m = 1.03 and SEE = 0.02). In patients undergoing cardiac catheterization, Doppler catheter-determined cardiac output appeared to modestly underestimate Fick cardiac output (r = 0.82, m = 0.80 and SEE = 0.09; mean error +/- SEM = -0.26 +/- 0.14 liters/min). However, predictive accuracy was comparable to simultaneously obtained thermodilution measurements (r = 0.85, m = 1.07 and SEE = 0.10; mean error +/- SEM = 0.61 +/- 0.16 liters/min). This new Doppler catheter system utilizes multiple ultrasound transducers to provide angle-independent measurements of vessel diameter and instantaneous velocity within the main pulmonary artery, resulting in a more accurate assessment of Doppler-derived cardiac output. In addition, useful information concerning hemodynamic variables such as peak flow, acceleration, deceleration, stroke work and pulmonary impedance may be derived.

  14. Comparison of cardiac output measures by transpulmonary thermodilution, pulse contour analysis, and pulmonary artery thermodilution during off-pump coronary artery bypass surgery: a subgroup analysis of the cardiovascular anaesthesia registry at a single tertiary centre.

    PubMed

    Cho, Youn Joung; Koo, Chang-Hoon; Kim, Tae Kyong; Hong, Deok Man; Jeon, Yunseok

    2016-12-01

    Cardiac output measurement has a long history in haemodynamic management and many devices are now available with varying levels of accuracy. The purpose of the study was to compare the agreement and trending abilities of cardiac output, as measured by transpulmonary thermodilution and calibrated pulse contour analysis, using the VolumeView™ system, continuous thermodilution via a pulmonary artery catheter, and uncalibrated pulse contour analysis, using FloTrac™ with pulmonary artery bolus thermodilution. Twenty patients undergoing off-pump coronary artery bypass surgery using a pulmonary artery catheter and the VolumeView™ and FloTrac™ systems were included in this subgroup analysis of the cardiovascular anaesthesia registry at a single tertiary centre. During surgery, cardiac output was assessed after the induction of anaesthesia, after sternotomy, during the harvesting of grafts, during revascularization of the anterior and posterior/lateral wall, after protamine infusion, and after sternal fixation. In total, 145 sets of measurements were evaluated using Bland-Altman with % error calculation, correlation, concordance, and polar plot analyses. The percentage error (bias, limits of agreement) was 12.6 % (-0.12, -0.64 to 0.41 L/min), 26.7 % (-0.38, -1.50 to 0.74 L/min), 29.3 % (-0.08, -1.32 to 1.15 L/min), and 33.8 % (-0.05, -1.47 to 1.37 L/min) for transpulmonary thermodilution, pulmonary artery continuous thermodilution, calibrated, and uncalibrated pulse contour analysis, respectively, compared with pulmonary artery bolus thermodilution. All pairs of measurements showed significant correlations (p < 0.001), whereas only transpulmonary thermodilution revealed trending ability (concordance rate of 95.1 %, angular bias of 1.33°, and radial limits of agreement of 28.71°) compared with pulmonary artery bolus thermodilution. Transpulmonary thermodilution using the VolumeView™ system provides reliable data on cardiac output measurement and

  15. Clinical evaluation of a diameter sensing Doppler cardiac output meter.

    PubMed

    Niclou, R; Teague, S M; Lee, R

    1990-04-01

    A concentric beam Doppler ultrasonic flowmeter has been developed. This instrument has capacity for independent assessment of volumetric flow, as it determines flow cross-section area, stroke length, and pulse rate from the Doppler signals alone. The method is practically independent of the angle of interrogation. We used this device and obtained noninvasive estimates of cardiac output in 54 patients undergoing invasive assessment of cardiac output by thermodilution, Fick, or indicator dye methods (x). Correlations against pooled cardiac output reference standards ranged from r = .86 (y = .86x + 1.03) in 26 studies of high confidence to r = .45 (y = .30x + 2.62) in 17 studies under difficult conditions. The overall correlation was r = .68 (y = .63x + 1.49, n = 87). Noninvasive results of experienced and inexperienced operators were similar (r = .87). The instrument returned accurate assessments of heart rate (r = .83), but underestimated stroke length (r = .72) and appeared to be limited in the assessment of aortic diameters less than 28 or greater than 31 mm (r = .23). We conclude that stand-alone Doppler assessment of cardiac output is appealing and feasible, but difficult or impossible in many ICU scenarios. Further evolution of the concentric beam Doppler approach is needed and anticipated.

  16. Continuous cardiac output monitoring via arterial pressure waveform analysis following severe hemorrhagic shock in dogs.

    PubMed

    Cooper, Edward S; Muir, William W

    2007-07-01

    To determine agreement and correlation between cardiac output determined by arterial pressure waveform analysis (PulseCO) and the lithium dilution indicator technique (LiDCO) during severe hemorrhagic shock and after fluid resuscitation in dogs. Prospective experimental study. University research laboratory. Twelve adult mongrel dogs. Dogs were anesthetized, and selected arteries and veins were catheterized. Baseline cardiac output was determined by LiDCO and used to calibrate the PulseCO. Hemorrhagic shock was induced by withdrawing blood to achieve and maintain a mean arterial pressure of 30-40 mm Hg for 60 mins, and cardiac output was measured again using both methods. All dogs were resuscitated by administering lactated Ringer's solution intravenously to achieve and maintain a mean arterial pressure between 60 and 70 mm Hg. PulseCO and LiDCO values were measured at 10 and 120 mins after resuscitation. Mean baseline cardiac output was 2.93 +/- 0.45 L/min. PulseCO values overestimated cardiac output compared with LiDCO during hemorrhagic shock (2.25 vs. 0.78 L/min). There were no differences in cardiac output determined by PulseCO and LiDCO at 10 and 120 mins after fluid resuscitation. Bland-Altman analysis suggested that PulseCO values were inaccurate after hemorrhage, producing significant bias with wide limits of agreement and percentage error (1.47 +/- 1.46 L/min; 97%). Bias was small but the limits of agreement and percentage error were large for cardiac output at 10 and 120 mins after resuscitation (-0.1 +/- 1.88 [98%] and -0.17 +/- 1.32 [71%] L/min, respectively). There appeared to be a negative but not significant correlation after hemorrhage (r = -.45; p = .15). PulseCO determination of cardiac output does not accurately predict rapid decreases in cardiac output or the effects of fluid resuscitation in dogs. Recalibration of PulseCO may be necessary after any apparent or suspected decrease in cardiac preload, afterload, or contractility.

  17. Cardiac power output and its response to exercise in athletes and non-athletes.

    PubMed

    Klasnja, Aleksandar V; Jakovljevic, Djordje G; Barak, Otto F; Popadic Gacesa, Jelena Z; Lukac, Damir D; Grujic, Nikola G

    2013-05-01

    Cardiac power output (CPO) is an integrative measure of overall cardiac function as it accounts for both, flow- and pressure-generating capacities of the heart. The purpose of the present study was twofold: (i) to assess cardiac power output and its response to exercise in athletes and non-athletes and (ii) to determine the relationship between cardiac power output and reserve and selected measures of cardiac function and structure. Twenty male athletes and 32 age- and gender-matched healthy sedentary controls participated in this study. CPO was calculated as the product of cardiac output and mean arterial pressure, expressed in watts. Measures of hemodynamic status, cardiac structure and pumping capability were assessed by echocardiography. CPO was assessed at rest and after peak bicycle exercise. At rest, the two groups had similar values of cardiac power output (1·08 ± 0·2 W versus 1·1 ± 0·24 W, P>0·05), but the athletes demonstrated lower systolic blood pressure (109·5 ± 6·2 mmHg versus 117·2 ± 8·2 mmHg, P<0·05) and thicker posterior wall of the left ventricle (9·8 ± 1 mm versus 9 ± 1·1 mm, P<0·05). Peak CPO was higher in athletes (5·87 ± 0·75 W versus 5·4 ± 0·69 W, P<0·05) as was cardiac reserve (4·92 ± 0·66 W versus 4·26 ± 0·61 W, P<0·05), respectively. Peak exercise CPO and reserve were only moderately correlated with end-diastolic volume (r = 0·54; r = 0·46, P<0·05) and end-diastolic left ventricular internal diameter (r = 0·48; r = 0·42, P<0·05), respectively. Athletes demonstrated greater maximal cardiac pumping capability and reserve than non-athletes. The study provides new evidence that resting measures of cardiac structure and function need to be considered with caution in interpretation of maximal cardiac performance.

  18. Reference Values for Peak Exercise Cardiac Output in Healthy Individuals.

    PubMed

    Agostoni, Piergiuseppe; Vignati, Carlo; Gentile, Piero; Boiti, Costanza; Farina, Stefania; Salvioni, Elisabetta; Mapelli, Massimo; Magrì, Damiano; Paolillo, Stefania; Corrieri, Nicoletta; Sinagra, Gianfranco; Cattadori, Gaia

    2017-06-01

    Cardiac output (Q˙) is a key parameter in the assessment of cardiac function, its measurement being crucial for the diagnosis, treatment, and prognostic evaluation of all heart diseases. Until recently, Q˙ determination at peak exercise has been possible through invasive methods, so that normal values were obtained in studies based on small populations. Nowadays, peak Q˙ can be measured noninvasively by means of the inert gas rebreathing (IGR) technique. The present study was undertaken to provide reference values for peak Q˙ in the normal general population and to obtain a formula able to estimate peak exercise Q˙ from measured peak oxygen uptake (V˙o2). We studied 500 normal subjects (age, 44.9 ± 1.5 years; range, 18-77 years; 260 men, 240 women) who underwent a maximal cardiopulmonary exercise test with peak Q˙ measurement by IGR. In the overall study sample, peak Q˙ was 13.2 ± 3.5 L/min (men, 15.3 ± 3.3 L/min; women, 11.0 ± 2.0 L/min; P < .001) and peak V˙o2 was 95% ± 18% of the maximum predicted value (men, 95% ± 19%; women, 95% ± 18%). Peak V˙o2 and peak Q˙ progressively decreased with age (R(2), 0.082; P < .001; and R(2), 0.144; P < .001, respectively). The V˙o2-derived formula to measure Q˙ at peak exercise was (4.4 × peak V˙o2) + 4.3 in the overall study cohort, (4.3 × peak V˙o2) + 4.5 in men, and (4.9 × peak V˙o2) + 3.6 in women. The simultaneous measurement of Q˙ and V˙o2 at peak exercise in a large sample of healthy subjects provided an equation to predict peak Q˙ from peak V˙o2 values. Copyright © 2017 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  19. [Arterial pressure-based cardiac output monitoring: 1. FloTrac sensor and SVV].

    PubMed

    Seo, Katsuhiro

    2009-07-01

    FloTrac is a recently introduced semi-invasive arterial pressure-based cardiac output (APCO) monitoring device. The accuracy of a new device is usually evaluated by Bland-Altman method, which shows graphically the mean value of differences between a new method and the reference method (bias), standard deviation of the differences (precision) and limits of agreement or 2 standard deviations. Critchley et al calculated the percentage errors which are two standard deviations divided by mean cardiac output, and proposed that percentage error should be less than 30% as a reliable new method. Cardiac output was measured by FloTrac (APCO) and pulmonary arterial catheter-based thermodilution method (ICO) during off-pump coronary artery bypass and resection of pheochromocytoma, procedures associated with hemodynamically unstable conditions. As algorithm is renewed in a new version of the device, the accuracy of the device is improved; bias, precision and limits of agreement decreased; correlation coefficient increased, and percentage error was assessed to be around 30%. On the other hand, there was a tendency for increased negative bias as cardiac output increased, implying APCO tends to underestimate ICO in high CO ranges. APCO is less invasive and could rapidly respond to fast changes of hemodynamic state. FloTrac is expected to become a reliable cardiac output monitoring device even under hemodynamically unstable conditions. Further improvement of the algorithm is anticipated.

  20. Risk factors for decreased cardiac output after coronary artery bypass grafting: a prospective cohort study.

    PubMed

    Dos Santos, Eduarda Ribeiro; Lopes, Camila Takao; Maria, Vera Lucia Regina; de Barros, Alba Lucia Bottura Leite

    2017-04-01

    No previous study has investigated the predictive risk factors of the nursing diagnosis of risk for decreased cardiac output after coronary artery bypass grafting (CABG). This study aimed to identify the predictive risk factors of the nursing diagnosis of risk for decreased cardiac output after CABG. This was a prospective cohort study performed at a cardiac university hospital in São Paulo, Brazil and 257 adult patients undergoing CABG were included. Potential risk factors for low cardiac output in the immediate post-operative period were investigated using the patients' medical records. Univariate analysis and logistic regression were used to identify the predictive risk factors of decreased cardiac output. The area under the receiver operating characteristic curve was calculated as a measure of accuracy. The variables that could not be analysed through logistic regression were analysed through Fisher's exact test. One hundred and ninety-five patients had low cardiac output in the immediate post-operative period. The predictive risk factors included age ⩾60 years, decreased left ventricle ejection fraction, not using the radial artery graft, positive fluid balance and post-operative arrhythmia that differed from the pre-operative arrhythmia. This model predicted the outcome with a sensitivity of 62.9%, a specificity of 87.2% and an accuracy of 81.5%. The variables analysed through Fisher's exact test included heart failure, re-exploration and bleeding-related re-exploration. The predictive risk factors for the nursing diagnosis of risk for decreased cardiac output after CABG were found. These results can be used to direct nurses in patient monitoring, staff training and nursing team staffing.

  1. Volume loading augments cutaneous vasodilatation and cardiac output of heat stressed older adults.

    PubMed

    Gagnon, Daniel; Romero, Steven A; Ngo, Hai; Sarma, Satyam; Cornwell, William K; Poh, Paula Y S; Stoller, Douglas; Levine, Benjamin D; Crandall, Craig G

    2017-08-21

    Age-related changes in cutaneous microvascular and cardiac functions limit the extent of cutaneous vasodilatation and the increase in cardiac output that healthy older adults can achieve during passive heat stress. However, it is unclear if these age-related changes in microvascular and cardiac functions maximally restrain the levels of cutaneous vasodilatation and cardiac output that healthy older adults can achieve during heat stress. We observed that rapid volume loading, performed during passive heat stress, augments both cutaneous vasodilatation and cardiac output in healthy older humans. These findings demonstrate that the microcirculation of healthy aged skin can further dilate during passive heat exposure, despite peripheral limitations to vasodilatation. Furthermore, healthy older humans can augment cardiac output when cardiac pre-load is increased during heat stress. Primary ageing markedly attenuates cutaneous vasodilatation and the increase in cardiac output during passive heating. However, it remains unclear if these responses are maximally restrained by age-related changes in cutaneous microvascular and cardiac functions. We hypothesized that rapid volume loading performed during heat stress would increase cardiac output in older adults without parallel increases in cutaneous vasodilatation. Twelve young (Y: 26 ± 5 years) and ten older (O: 69 ± 3 years) healthy adults were passively heated until core temperature increased by 1.5°C. Cardiac output (thermodilution), forearm vascular conductance (FVC, venous occlusion plethysmography) and cutaneous vascular conductance (CVC, laser-Doppler) were measured before and after rapid infusion of warmed saline (15 mL kg(-1) , ∼7 min). While heat stressed, but prior to saline infusion, cardiac output (O: 6.8 ± 0.4 vs. Y: 9.4 ± 0.6 L min(-1) ), FVC (O: 0.08 ± 0.01 vs. Y: 0.17 ± 0.02 mL (100 mL min(-1)  mmHg(-1) )(-1) ), and CVC (O: 1.29 ± 0.34 vs. Y: 1.93 ± 0.30

  2. Combined doppler and phased-array echocardiographic estimation of cardiac output.

    PubMed

    Magnin, P A; Stewart, J A; Myers, S; von Ramm, O; Kisslo, J A

    1981-02-01

    The capability of a pulsed Doppler flowmeter combined with a phased-array imaging system to measure volume flow was tested in vitro and in patients undergoing cardiac catheterization. The Doppler-phased-array system (DPA) was used to determine vessel diameter and a superimposed cursor was used to locate the range and angle of the Doppler sample volume. DPA estimates of continuous flow through tubing in a water tank correlated strongly (r = 0.99) with measured flow corresponding to physiologic ranges from 3-12 l/min. For pulsatile flow in a water tank, a correlation of r = 0.86 with measured flow was obtained, whereas DPA estimates of cardiac outputs compared with Fick estimates in the 11 patients produced a correlation of r = 0.83. These data indicate that estimates of cardiac output are possible using the DPA approach.

  3. Use of thermodilution cardiac output overestimates diagnoses of exercise-induced pulmonary hypertension

    PubMed Central

    Hsu, Steven; Brusca, Samuel B.; Rhodes, Parker S.; Kolb, Todd M.; Mathai, Stephen C.

    2017-01-01

    Two new definitions of exercise-induced pulmonary hypertension (EIPH) have emerged. Both rely on measuring cardiac output (CO), yet this remains unstandardized. In our cohort of patients undergoing invasive cardiopulmonary exercise testing, we found that using thermodilution CO rather than direct Fick CO led to a significant excess of EIPH diagnoses. PMID:28680584

  4. Use of thermodilution cardiac output overestimates diagnoses of exercise-induced pulmonary hypertension.

    PubMed

    Hsu, Steven; Brusca, Samuel B; Rhodes, Parker S; Kolb, Todd M; Mathai, Stephen C; Tedford, Ryan J

    2017-03-01

    Two new definitions of exercise-induced pulmonary hypertension (EIPH) have emerged. Both rely on measuring cardiac output (CO), yet this remains unstandardized. In our cohort of patients undergoing invasive cardiopulmonary exercise testing, we found that using thermodilution CO rather than direct Fick CO led to a significant excess of EIPH diagnoses.

  5. Peripheral vasodilatation determines cardiac output in exercising humans: insight from atrial pacing.

    PubMed

    Bada, A A; Svendsen, J H; Secher, N H; Saltin, B; Mortensen, S P

    2012-04-15

    In dogs, manipulation of heart rate has no effect on the exercise-induced increase in cardiac output. Whether these findings apply to humans remain uncertain, because of the large differences in cardiovascular anatomy and regulation. To investigate the role of heart rate and peripheral vasodilatation in the regulation of cardiac output during steady-state exercise, we measured central and peripheral haemodynamics in 10 healthy male subjects, with and without atrial pacing (100–150 beats min(−1)) during: (i) resting conditions, (ii) one-legged knee extensor exercise (24 W) and (iii) femoral arterial ATP infusion at rest. Exercise and ATP infusion increased cardiac output, leg blood flow and vascular conductance (P < 0.05), whereas cerebral perfusion remained unchanged. During atrial pacing increasing heart rate by up to 54 beats min(−1), cardiac output did not change in any of the three conditions, because of a parallel decrease in stroke volume (P < 0.01). Atrial pacing increased mean arterial pressure (MAP) at rest and during ATP infusion (P < 0.05), whereas MAP remained unchanged during exercise. Atrial pacing lowered central venous pressure (P < 0.05) and pulmonary capillary wedge pressure (P < 0.05) in all conditions, whereas it did not affect pulmonary mean arterial pressure. Atrial pacing lowered the left ventricular contractility index (dP/dt) (P < 0.05) in all conditions and plasma noradrenaline levels at rest (P < 0.05), but not during exercise and ATP infusion. These results demonstrate that the elevated cardiac output during steady-state exercise is regulated by the increase in skeletal muscle blood flow and venous return to the heart, whereas the increase in heart rate appears to be secondary to the regulation of cardiac output.

  6. Cardiac output during exercise: a comparison of four methods.

    PubMed

    Siebenmann, C; Rasmussen, P; Sørensen, H; Zaar, M; Hvidtfeldt, M; Pichon, A; Secher, N H; Lundby, C

    2015-02-01

    Several techniques assessing cardiac output (Q) during exercise are available. The extent to which the measurements obtained from each respective technique compares to one another, however, is unclear. We quantified Q simultaneously using four methods: the Fick method with blood obtained from the right atrium (Q(Fick-M)), Innocor (inert gas rebreathing; Q(Inn)), Physioflow (impedance cardiography; Q(Phys)), and Nexfin (pulse contour analysis; Q(Pulse)) in 12 male subjects during incremental cycling exercise to exhaustion in normoxia and hypoxia (FiO2  = 12%). While all four methods reported a progressive increase in Q with exercise intensity, the slopes of the Q/oxygen uptake (VO2) relationship differed by up to 50% between methods in both normoxia [4.9 ± 0.3, 3.9 ± 0.2, 6.0 ± 0.4, 4.8 ± 0.2 L/min per L/min (mean ± SE) for Q(Fick-M), Q(Inn), QP hys and Q(Pulse), respectively; P = 0.001] and hypoxia (7.2 ± 0.7, 4.9 ± 0.5, 6.4 ± 0.8 and 5.1 ± 0.4 L/min per L/min; P = 0.04). In hypoxia, the increase in the Q/VO2 slope was not detected by Nexfin. In normoxia, Q increases by 5-6 L/min per L/min increase in VO2, which is within the 95% confidence interval of the Q/VO2 slopes determined by the modified Fick method, Physioflow, and Nexfin apparatus while Innocor provided a lower value, potentially reflecting recirculation of the test gas into the pulmonary circulation. Thus, determination of Q during exercise depends significantly on the applied method.

  7. Reliability of peak VO(2) and maximal cardiac output assessed using thoracic bioimpedance in children.

    PubMed

    Welsman, Joanne; Bywater, Katie; Farr, Colin; Welford, Deborah; Armstrong, Neil

    2005-06-01

    The purpose of this study was to evaluate the reliability of a thoracic electrical bioimpedance based device (PhysioFlow) for the determination of cardiac output and stroke volume during exercise at peak oxygen uptake (peak VO(2) in children. The reliability of peak VO(2) is also reported. Eleven boys and nine girls aged 10-11 years completed a cycle ergometer test to voluntary exhaustion on three occasions each 1 week apart. Peak VO(2) was determined and cardiac output and stroke volume at peak VO(2) were measured using a thoracic bioelectrical impedance device (PhysioFlow). The reliability of peak VO(2) cardiac output and stroke volume were determined initially from pairwise comparisons and subsequently across all three trials analysed together through calculation of typical error and intraclass correlation. The pairwise comparisons revealed no consistent bias across tests for all three measures and there was no evidence of non-uniform errors (heteroscedasticity). When three trials were analysed together typical error expressed as a coefficient of variation was 4.1% for peak VO(2) 9.3% for cardiac output and 9.3% for stroke volume. Results analysed by sex revealed no consistent differences. The PhysioFlow method allows non-invasive, beat-to-beat determination of cardiac output and stroke volume which is feasible for measurements during maximal exercise in children. The reliability of the PhysioFlow falls between that demonstrated for Doppler echocardiography (5%) and CO(2) rebreathing (12%) at maximal exercise but combines the significant advantages of portability, lower expense and requires less technical expertise to obtain reliable results.

  8. Exercise cardiac output following Skylab missions - The second manned Skylab mission

    NASA Technical Reports Server (NTRS)

    Buderer, M. C.; Mauldin, D. G.; Rummel, J. A.; Michel, E. L.; Sawin, C. F.

    1976-01-01

    Cardiac output was measured during preflight and postflight exercise-stress tests on the Skylab astronauts. In the postflight tests immediately following the 28-, 59-, and 84-d earth orbital missions, the astronauts exhibited an approximate 30% decrease in cardiac output coupled with an approximate 50% decrease in cardiac stroke volume during exercise. These changes were accompanied by elevated heart rates and significant increases in total systemic peripheral vascular resistance. Mean arterial pressure was unchanged. All parameters returned to normal preflight values within 30 d of the end of the orbital period. Duration of the zero-G exposure did not appear to influence either the magnitude of the hemodynamic changes or the time-course of their return to normal. These results are discussed in relation to other cardiovascular findings and possible mechanisms responsible for the observations are outlined.

  9. Exercise cardiac output following Skylab missions - The second manned Skylab mission

    NASA Technical Reports Server (NTRS)

    Buderer, M. C.; Mauldin, D. G.; Rummel, J. A.; Michel, E. L.; Sawin, C. F.

    1976-01-01

    Cardiac output was measured during preflight and postflight exercise-stress tests on the Skylab astronauts. In the postflight tests immediately following the 28-, 59-, and 84-d earth orbital missions, the astronauts exhibited an approximate 30% decrease in cardiac output coupled with an approximate 50% decrease in cardiac stroke volume during exercise. These changes were accompanied by elevated heart rates and significant increases in total systemic peripheral vascular resistance. Mean arterial pressure was unchanged. All parameters returned to normal preflight values within 30 d of the end of the orbital period. Duration of the zero-G exposure did not appear to influence either the magnitude of the hemodynamic changes or the time-course of their return to normal. These results are discussed in relation to other cardiovascular findings and possible mechanisms responsible for the observations are outlined.

  10. Cardiac output and venous return as interdependent and independent variables.

    PubMed

    Badeer, H S

    1981-01-01

    Under steady states the heart pumps whatever it receives and receives whatever it pumps. In other words, cardiac output (CO) and venous return (VR) are equal and the distinction between the two seems unnecessary. However, under nonsteady states the two are temporarily unequal and the distinction becomes significant. VR varies directly with the difference in pressure between the end of systemic capillaries and the right ventricle during filling and inversely with the total resistance of the venous system. Thus, the energy for VR is derived from CO. In some transient states VR becomes an independent variable and CO dependent until a new steady state is reached (e.g., exercise, hemorrhage, fevers, hyperthyroidism, severe anemia, etc.). In other conditions the opposite is true (e.g., myocardial infarction, altered ventricular contractility, etc.). Explanation of changes in cardiac output in various perturbations of circulation are based on the identification of the independent variable (VR or CO) in a given physiologic or pathologic condition during the period that a nonsteady state exists.

  11. Non-invasive cardiac output trending during exercise recovery on a bathroom-scale-based ballistocardiograph.

    PubMed

    Inan, O T; Etemadi, M; Paloma, A; Giovangrandi, L; Kovacs, G T A

    2009-03-01

    Cardiac ejection of blood into the aorta generates a reaction force on the body that can be measured externally via the ballistocardiogram (BCG). In this study, a commercial bathroom scale was modified to measure the BCGs of nine healthy subjects recovering from treadmill exercise. During the recovery, Doppler echocardiogram signals were obtained simultaneously from the left ventricular outflow tract of the heart. The percentage changes in root-mean-square (RMS) power of the BCG were strongly correlated with the percentage changes in cardiac output measured by Doppler echocardiography (R(2) = 0.85, n = 275 data points). The correlation coefficients for individually analyzed data ranged from 0.79 to 0.96. Using Bland-Altman methods for assessing agreement, the mean bias was found to be -0.5% (+/-24%) in estimating the percentage changes in cardiac output. In contrast to other non-invasive methods for trending cardiac output, the unobtrusive procedure presented here uses inexpensive equipment and could be performed without the aid of a medical professional.

  12. Evaluation of two methods for continuous cardiac output assessment during exercise in chronic heart failure patients.

    PubMed

    Kemps, Hareld M C; Thijssen, Eric J M; Schep, Goof; Sleutjes, Boudewijn T H M; De Vries, Wouter R; Hoogeveen, Adwin R; Wijn, Pieter F F; Doevendans, Pieter A F M

    2008-12-01

    The purpose of this study was to evaluate the accuracy of two techniques for the continuous assessment of cardiac output in patients with chronic heart failure (CHF): a radial artery pulse contour analysis method that uses an indicator dilution method for calibration (LiDCO) and an impedance cardiography technique (Physioflow), using the Fick method as a reference. Ten male CHF patients (New York Heart Association class II-III) were included. At rest, cardiac output values obtained by LiDCO and Physioflow were compared with those of the direct Fick method. During exercise, the continuous Fick method was used as a reference. Exercise, performed on a cycle ergometer in upright position, consisted of two constant-load tests at 30% and 80% of the ventilatory threshold and a symptom-limited maximal test. Both at rest and during exercise LiDCO showed good agreement with reference values [bias +/- limits of agreement (LOA), -1% +/- 28% and 2% +/- 28%, respectively]. In contrast, Physioflow overestimated reference values both at rest and during exercise (bias +/- LOA, 48% +/- 60% and 48% +/- 52%, respectively). Exercise-related within-patient changes of cardiac output, expressed as a percent change, showed for both techniques clinically acceptable agreement with reference values (bias +/- LOA: 2% +/- 26% for LiDCO, and -2% +/- 36% for Physioflow, respectively). In conclusion, although the limits of agreement with the Fick method are pretty broad, LiDCO provides accurate measurements of cardiac output during rest and exercise in CHF patients. Although Physioflow overestimates cardiac output, this method may still be useful to estimate relative changes during exercise.

  13. Maximal cardiac output during arm exercise in the sitting position after cervical spinal cord injury.

    PubMed

    Hostettler, Stefanie; Leuthold, Lorenz; Brechbühl, Jörg; Mueller, Gabi; Illi, Sabine K; Spengler, Christina M

    2012-02-01

    To determine and compare haemodynamic responses at maximal arm-crank (ACE) and wheelchair exercise (WCE) in individuals with cervical spinal cord injury and pair-matched able-bodied individuals. Nine male, motor-complete cervical spinal cord injured and 9 able-bodied individuals performed graded, maximal ACE and WCE. Cardiac output, heart rate, and stroke volume were determined at rest and at maximal exercise in cervical spinal cord injured individuals. In able-bodied individuals, measurements were performed at rest and at the maximal workload of the matched cervical spinal cord injured individuals. In cervical spinal cord injured, maximal cardiac output (ACE 7.4 (standard deviation (SD) 1.6); WCE 7.3 (SD 2.1) l/min) and heart rate (ACE 101 (SD 22); WCE 103 (SD 27) bpm) increased significantly compared with rest (4.6 (SD 1.0) l/min; 65 (SD 12) bpm), while stroke volume (ACE 77 (SD 22); WCE 73 (SD 21) ml) did not differ from rest (73 (SD 20) ml). In able-bodied individuals, cardiac output (rest 4.8 (SD 1.4); ACE 10.7 (SD 1.8); WCE 10.3 (SD 2.2) l/min), heart rate (rest 68 (SD 10); ACE 103 (SD 27); WCE 109 (SD 27) bpm), and stroke volume (rest 70 (SD 10); ACE 105 (SD 20); WCE 96 (SD 17) ml) increased significantly compared with rest. Cardiac output and stroke volume were significantly lower in cervical spinal cord injured compared with able-bodied individuals at the same workloads. Haemodynamic responses to maximal exercise were similar for both exercise modes in individuals with cervical spinal cord injury. The lower cardiac output in individuals with cervical spinal cord injury compared with able-bodied individuals at equivalent workloads reflects the inability of the circulatory system to increase stroke volume.

  14. High Power Amplifier Harmonic Output Level Measurement

    NASA Technical Reports Server (NTRS)

    Perez, R. M.; Hoppe, D. J.; Khan, A. R.

    1995-01-01

    A method is presented for the measurement of the harmonic output power of high power klystron amplifiers, involving coherent hemispherical radiation pattern measurements of the radiated klystron output. Results are discussed for the operation in saturated and unsaturated conditions, and with a waveguide harmonic filter included.

  15. High Power Amplifier Harmonic Output Level Measurement

    NASA Technical Reports Server (NTRS)

    Perez, R. M.; Hoppe, D. J.; Khan, A. R.

    1995-01-01

    A method is presented for the measurement of the harmonic output power of high power klystron amplifiers, involving coherent hemispherical radiation pattern measurements of the radiated klystron output. Results are discussed for the operation in saturated and unsaturated conditions, and with a waveguide harmonic filter included.

  16. Control of cardiac output in thyrotoxic calves. Evaluation of changes in the systemic circulation.

    PubMed Central

    Goldman, S; Olajos, M; Morkin, E

    1984-01-01

    The contribution of peripheral vascular factors to the high output state in thyrotoxicosis was examined in 11 calves treated with daily intramuscular injections of L-thyroxine (200 micrograms/kg) for 12-14 d. Thyroxine treatment increased cardiac output from 14.1 +/- 1.4 to 24.7 +/- 1.4 liters/min (P less than 0.001) and decreased systemic vascular resistance from 562 +/- 65 to 386 +/- 30 dyn-s/cm5 (P less than 0.01). Blood volume was increased from 65 +/- 4 ml/kg in the euthyroid state to 81 +/- 6 ml/kg when the animals were thyrotoxic (P less than 0.05). The role of low peripheral vascular resistance in maintenance of the high output state was evaluated by infusion of phenylephrine at two dosages (2.5 and 4.0 micrograms/kg per min). In the euthyroid state, no significant decrease in cardiac output was observed at either level of pressor infusion. In the thyrotoxic state, the higher dosage of phenylephrine increased peripheral resistance to the euthyroid control level and caused a small (6%) decrease in cardiac output (P less than 0.05). This small decrease in cardiac output probably could be attributed to the marked increase in left ventricular afterload caused by the pressor infusion as assessed from measurements of intraventricular pressure and dimensions. Changes in the venous circulation were evaluated by measurement of mean circulatory filling pressure and the pressure gradient for venous return in six animals during cardiac arrest induced by injection of acetylcholine into the pulmonary artery. Mean circulatory filling pressure increased from 10 +/- 1 mmHg in the euthyroid state to 16 +/- 2 mmHg (P less than 0.01) during thyrotoxicosis, while pressure gradient for venous return increased from 10 +/- 1 to 14 +/- 2 mmHg (P less than 0.02). These changes in venous return curves were not affected significantly by ganglionic blockade with trimethapan (2.0 mg/kg per min) before cardiac arrest. Thus, the high output state associated with thyrotoxicosis is not

  17. The decrease of cardiac chamber volumes and output during positive-pressure ventilation.

    PubMed

    Kyhl, Kasper; Ahtarovski, Kiril Aleksov; Iversen, Kasper; Thomsen, Carsten; Vejlstrup, Niels; Engstrøm, Thomas; Madsen, Per Lav

    2013-10-01

    Positive-pressure ventilation (PPV) is widely used for treatment of acute cardiorespiratory failure, occasionally at the expense of compromised cardiac function and arterial blood pressure. The explanation why has largely rested on interpretation of intracardiac pressure changes. We evaluated the effect of PPV on the central circulation by studying cardiac chamber volumes with cardiac magnetic resonance imaging (CMR). We hypothesized that PPV lowers cardiac output (CO) mainly via the Frank-Starling relationship. In 18 healthy volunteers, cardiac chamber volumes and flow in aorta and the pulmonary artery were measured by CMR during PPV levels of 0, 10, and 20 cmH2O applied via a respirator and a face mask. All cardiac chamber volumes decreased in proportion to the level of PPV. Following 20-cmH2O PPV, the total diastolic and systolic cardiac volumes (±SE) decreased from 605 (±29) ml to 446 (±29) ml (P < 0.001) and from 265 (±17) ml to 212 (±16) ml (P < 0.001). Left ventricular stroke volume decreased by 27 (±4) ml/beat; heart rate increased by 7 (±2) beats/min; and CO decreased by 1.0 (±0.4) l/min (P < 0.001). From 0 to 20 cmH2O, right and left ventricular peak filling rates decreased by -146 (±32) and -187 (±64) ml/s (P < 0.05) but maximal emptying rates were unchanged. Cardiac filling and output decrease with increasing PPV in healthy volunteers. The decrease is seen even at low levels of PPV and should be taken into account when submitting patients to mechanical ventilation with positive pressures. The decrease in CO is fully explained by the Frank-Starling mechanism.

  18. The relationship between the flow of arteriovenous fistula and cardiac output in haemodialysis patients.

    PubMed

    Basile, Carlo; Lomonte, Carlo; Vernaglione, Luigi; Casucci, Francesco; Antonelli, Maurizio; Losurdo, Nicola

    2008-01-01

    Satisfactory haemodialysis (HD) vascular access flow (Qa) is necessary for dialysis adequacy. High Qa is postulated to increase cardiac output (CO) and cause high-output cardiac failure. Aim of the present prospective study was to evaluate the relationship between Qa of arteriovenous fistulas (AVFs) and CO in order to have a closer insight into this scarcely explored aspect of HD pathophysiology. Ninety-six patients bearing an AVF entered the study. All were evaluated a priori for the existence of cardiac failure according to the functional classification of the American College of Cardiology/American Heart Association task force. Qa and CO were measured by means of the ultrasound dilution Transonic Hemodialysis Monitor HD02. The mean Qa of the 65 lower arm AVFs was 0.948+/-0.428 SD l/min, whereas that of the 31 upper arm AVFs was 1.58+/-0.553 l/min. The difference was statistically significant (P<0.001). Ten patients were classified as having high-output cardiac failure; seven of them bore an upper arm AVF. Thus, upper arm AVFs were associated with an increased risk of high-output cardiac failure (P<0.04, chi(2) test). A third-order polynomial regression model best fitted the relationship between Qa and CO. The analysis of the regression equation identified 0.95 and 2.2 l/min as Qa cut-off points. The receiver operating characteristic curve analysis showed that Qa values >or= 2.0 l/min predicted the occurrence of high-output cardiac failure more accurately than two other Qa values (sensitivity 89%, specificity 100%, curve area 0.99) and three Qa/CO ratio values (cardio-pulmonary recirculation-CPR). The better performance among the latter was that of CPR values >or= 20% (sensitivity 100%, specificity 74.7%, curve area 0.92). Our prospective study shows that the relationship between Qa of AVFs and CO is complex and a third-order polynomial regression model best fits this relationship. Furthermore, it is the first study to clearly show the high predictive power for

  19. Arterial pressure waveform derived cardiac output FloTrac/Vigileo system (third generation software): comparison of two monitoring sites with the thermodilution cardiac output.

    PubMed

    Vasdev, Sumit; Chauhan, Sandeep; Choudhury, Minati; Hote, Millind P; Malik, Madhur; Kiran, Usha

    2012-04-01

    The present study was conducted to study the effect of monitoring site, radial or femoral, for arterial pressure waveform derived cardiac output using FloTrac/Vigileo system with third generation software version 3.02 during cardiac surgery. The cardiac output derived from the two sites was also compared to the pulmonary artery catheter (PAC) derived cardiac output to reevaluate the relation between them using the newer software. The effect of cardiopulmonary bypass (CPB) was also studied by doing the sub analysis before and after bypass. Forty patients undergoing coronary artery bypass surgery with cardiopulmonary bypass were enrolled in the study. Cardiac output derived from radial artery (RADCO), femoral artery (FEMCO) using FloTrac/Vigileo system with third generation software version 3.02 and cardiac output using pulmonary artery catheter (PACCO) at predefined nine time points were recorded. Three hundred and forty two cardiac output data triplets were analysed. The Bland-Altman analysis of RADCO and FEMCO revealed a mean bias of -0.28 with percentage error of 20%. The pre CPB precision of both RADCO and FEMCO was 1.25 times as that of PACCO. The post CPB precision of FEMCO was 1.2 times of PACCO while that of RADCO was 1.7 times of PACCO. The third generation of FloTrac/Vigileo system shows good correlation between the radial and femoral derived cardiac outputs in both pre and post bypass periods. The newer software correlates better to PAC derived cardiac output in the post bypass period for femoral artery than radial artery.

  20. Power output measurement during treadmill cycling.

    PubMed

    Coleman, D A; Wiles, J D; Davison, R C R; Smith, M F; Swaine, I L

    2007-06-01

    The study aim was to consider the use of a motorised treadmill as a cycling ergometry system by assessing predicted and recorded power output values during treadmill cycling. Fourteen male cyclists completed repeated cycling trials on a motorised treadmill whilst riding their own bicycle fitted with a mobile ergometer. The speed, gradient and loading via an external pulley system were recorded during 20-s constant speed trials and used to estimate power output with an assumption about the contribution of rolling resistance. These values were then compared with mobile ergometer measurements. To assess the reliability of measured power output values, four repeated trials were conducted on each cyclist. During level cycling, the recorded power output was 257.2 +/- 99.3 W compared to the predicted power output of 258.2 +/- 99.9 W (p > 0.05). For graded cycling, there was no significant difference between measured and predicted power output, 268.8 +/- 109.8 W vs. 270.1 +/- 111.7 W, p > 0.05, SEE 1.2 %. The coefficient of variation for mobile ergometer power output measurements during repeated trials ranged from 1.5 % (95 % CI 1.2 - 2.0 %) to 1.8 % (95 % CI 1.5 - 2.4 %). These results indicate that treadmill cycling can be used as an ergometry system to assess power output in cyclists with acceptable accuracy.

  1. Initial Observations of the Effects of Calcium Chloride Infusions in Pediatric Patients with Low Cardiac Output.

    PubMed

    Averin, Konstantin; Villa, Chet; Krawczeski, Catherine D; Pratt, Jesse; King, Eileen; Jefferies, John L; Nelson, David P; Cooper, David S; Ryan, Thomas D; Sawyer, Jaclyn; Towbin, Jeffrey A; Lorts, Angela

    2016-03-01

    Myocardial contractility and relaxation are highly dependent on calcium homeostasis. Immature myocardium, as in pediatric patients, is thought to be more dependent on extracellular calcium for optimal function. For this reason, intravenous calcium chloride infusions may improve myocardial function in the pediatric patient. The objectives of this study were to report the hemodynamic changes seen after administration of continuous calcium chloride to critically ill children. We retrospectively identified pediatric patients (newborn to 17 years old) with hemodynamic instability admitted to the cardiac ICU between May 2011 and May 2012 who received a continuous infusion of calcium chloride. The primary outcome was improvement in cardiac output, assessed by arterial-mixed venous oxygen saturation (A-V) difference. Sixty-eight patients, mean age 0.87 ± 2.67 years, received a total of 116 calcium infusions. Calcium chloride infusions resulted in significant improvements in primary and secondary measures of cardiac output at 2 and 6 h. Six hours after calcium initiation, A-V oxygen saturation difference decreased by 7.4 % (32.6 ± 2.1 to 25.2 ± 2.0 %, p < 0.001), rSO2 increased by 5.5 % (63.1 vs 68.6 %, p < 0.001), and serum lactate decreased by 0.9 mmol/l (3.3 vs 2.4 mmol/l, p < 0.001) with no change in HR (149.1 vs 145.6 bpm p = 0.07). Urine output increased 0.66 ml/kg/h in the 8-h period after calcium initiation when compared to pre-initiation (p = 0.003). Neonates had the strongest evidence of effectiveness with other age groups trending toward significance. Calcium chloride infusions improve markers of cardiac output in a heterogenous group of pediatric patients in a cardiac ICU. Neonates appear to derive the most benefit from utilization of these infusions.

  2. Bioreactance is a reliable method for estimating cardiac output at rest and during exercise.

    PubMed

    Jones, T W; Houghton, D; Cassidy, S; MacGowan, G A; Trenell, M I; Jakovljevic, D G

    2015-09-01

    Bioreactance is a novel noninvasive method for cardiac output measurement that involves analysis of blood flow-dependent changes in phase shifts of electrical currents applied across the thorax. The present study evaluated the test-retest reliability of bioreactance for assessing haemodynamic variables at rest and during exercise. 22 healthy subjects (26 (4) yrs) performed an incremental cycle ergometer exercise protocol relative to their individual power output at maximal O2 consumption (Wmax) on two separate occasions (trials 1 and 2). Participants cycled for five 3 min stages at 20, 40, 60, 80 and 90% Wmax. Haemodynamic and cardiorespiratory variables were assessed at rest and continuously during the exercise protocol. Cardiac output was not significantly different between trials at rest (P=0.948), or between trials at any stage of the exercise protocol (all P>0.30). There was a strong relationship between cardiac output estimates between the trials (ICC=0.95, P<0.001) and oxygen consumption (ICC=0.99, P<0.001). Stroke volume was also not significantly different between trials at rest (P=0.989) or during exercise (all P>0.15), and strong relationships between trials were found (ICC=0.83, P<0.001). The bioreactance method demonstrates good test-retest reliability for estimating cardiac output at rest and during different stages of graded exercise testing including maximal exertion. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Evaluation of Resting Cardiac Power Output as a Prognostic Factor in Patients with Advanced Heart Failure.

    PubMed

    Yildiz, Omer; Aslan, Gamze; Demirozu, Zumrut T; Yenigun, Cemal Deniz; Yazicioglu, Nuran

    2017-09-15

    If the heart is represented by a hydraulic pump, cardiac power represents the hydraulic function of the heart. Cardiac pump function is frequently determined through left ventricular ejection fraction using imaging. This study aims to validate resting cardiac power output (CPO) as a predictive biomarker in patients with advanced heart failure (HF). One hundred and seventy-two patients with HF severe enough to warrant cardiac transplantation were retrospectively reviewed at a single tertiary care institution between September 2010 and July 2013. Patients were initially evaluated with simultaneous right-sided and left-sided cardiac catheter-based hemodynamic measurements, followed by longitudinal follow-up (median of 52 months) for adverse events (cardiac mortality, cardiac transplantation, or ventricular assist device placement). Median resting CPO was 0.54 W (long rank chi-square = 33.6; p < 0.0001). Decreased resting CPO (<0.54 W) predicted increased risk for adverse outcomes. Fifty cardiac deaths, 10 cardiac transplants, and 12 ventricular assist device placements were documented. The prognostic relevance of resting CPO remained significant after adjustment for age, gender, left ventricular ejection fraction, mean arterial pressure, pulmonary vascular resistance, right atrial pressure, and estimated glomerular filtration rate (HR, 3.53; 95% confidence interval, 1.66 to 6.77; p = 0.0007). In conclusion, lower resting CPO supplies independent prediction of adverse outcomes. Thus, it could be effectively used for risk stratification in patients with advanced HF. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Validation of an Ultrasound Cardiac Output Monitor as a Bedside Tool for Pediatric Patients.

    PubMed

    Beltramo, Fernando; Menteer, Jondavid; Razavi, Asma; Khemani, Robinder G; Szmuszkovicz, Jacqueline; Newth, Christopher J L; Ross, Patrick A

    2016-01-01

    The aim of our study was to determine the validity of cardiac output (CO) measurements taken with the ultrasonic cardiac output monitor (USCOM) by comparing to CO measured by pulmonary arterial catheter (PAC) thermodilution during cardiac catheterization. We enrolled thirty-one children (<18 years) undergoing cardiac catheterization in this double-blinded, prospective, observational study. The median CO measured by USCOM was 4.37 L/min (IQR 3.73, 5.60 L/min) compared to 4.28 L/min (IQR 3.52, 5.26 L/min) by PAC thermodilution. The bias (mean difference) between the two methods was 0.2 L/min, and the 95% limits of agreement were -1.2 to 1.6 L/min. The mean percentage error of CO between USCOM and PAC thermodilution was 11%. When excluding a sole outlier, the bias between the two measures decreased to 0.1 L/min (95% limits of agreement -0.6 to 0.9 L/min), and the percentage error was reduced to 8%. The median SVRI measured by USCOM was 22.0 Wood Units (IQR 17.0, 26.8 Wood Units) compared to 22.1 Wood Units (IQR 17.6, 27.4 Wood Units) by PAC thermodilution. Bias (mean difference) between the two methods was -0.6 Wood Units, and the 95% limits of agreement were -8.2 to 6.9 Wood Units. We found that the estimation of CO and by extension SVRI with USCOM is reliable against pulmonary artery catheter thermodilution in children with normal cardiac anatomy. Given the noninvasive nature of USCOM, speed of measurement, and relative ease of use, it may be useful as a bedside tool for pediatric patients.

  5. Thermodynamics of the heart: Relation between cardiac output and oxygen consumption

    NASA Astrophysics Data System (ADS)

    Uehara, Mituo; Sakane, Kumiko K.; Bertolotti, Simone A.

    2008-06-01

    A thermodynamic approach is used to derive a relation between cardiac output and rate of oxygen consumption. As an example, the relation is used to calculate the cardiac output of a young woman exercising on a treadmill. The results can be understood by undergraduates without any previous knowledge of human physiology.

  6. Cardiac output during high afterload artificial lung attachment.

    PubMed

    Kim, Jeongho; Sato, Hitoshi; Griffith, Grant W; Cook, Keith E

    2009-01-01

    Attachment of thoracic artificial lungs (TALs) can increase right ventricular (RV) afterload and decrease cardiac output (CO) under certain conditions. However, there is no established means of predicting the extent of RV dysfunction. The zeroth harmonic impedance modulus, Z0, was thus examined to determine its effectiveness at predicting CO during high afterload TAL attachment. The MC3 Biolung was attached in four adult sheep groups based on baseline (BL) pulmonary vascular resistance and TAL attachment mode: normal, parallel (n=7); normal, series (n=7); chronic pulmonary hypertension, parallel (n=5), and chronic pulmonary hypertension, series (n=5). The resistance of each attachment mode was increased incrementally and instantaneous pulmonary system hemodynamic data were acquired at each increment. The change in Z0 from BL, DeltaZ0, and percent change in CO (DeltaCO%) were then calculated to determine their relationship. The DeltaCO% varied significantly with DeltaZ0 (p<10(-40)) and DeltaZ02 (p<10(-4)) but not with the attachment and pulmonary hemodynamics group. The relationship between the variables for all sheep groups was DeltaCO%=0.215DeltaZ0(2)-7.14DeltaZ0+2.94 (R2=0.82) for DeltaZ0 in mm Hg/(L/min). Therefore, Z0 is an effective index for determining the CO during TAL attachment in both attachment modes with and without elevated pulmonary vascular resistance.

  7. Arterial pressure allows monitoring the changes in cardiac output induced by volume expansion but not by norepinephrine.

    PubMed

    Monnet, Xavier; Letierce, Alexia; Hamzaoui, Olfa; Chemla, Denis; Anguel, Nadia; Osman, David; Richard, Christian; Teboul, Jean-Louis

    2011-06-01

    To evaluate to which extent the systemic arterial pulse pressure could be used as a surrogate of cardiac output for assessing the effects of a fluid challenge and of norepinephrine. Observational study. Medical intensive care unit. Patients with an acute circulatory failure who received a fluid challenge (228 patients, group 1) or in whom norepinephrine was introduced or increased (145 patients, group 2). We measured the systolic, diastolic, and mean arterial pressure, pulse pressure, and the transpulmonary thermodilution cardiac output before and after the therapeutic interventions. In group 1, the fluid challenge significantly increased cardiac output by 24% ± 25%. It significantly increased cardiac output by ≥15% (+35% ± 27%) in 142 patients ("responders"). The fluid-induced changes in cardiac output were correlated with the changes in pulse pressure (r = .56, p < .0001), systolic arterial pressure (r = .55, p < .0001), diastolic arterial pressure (r = .37, p < .0001), and mean arterial pressure (r = .52, p < .0001). At multivariate analysis, changes in pulse pressure were significantly related to changes in stroke volume (multiple r = .52) and to age (r = .12). A fluid-induced increase in pulse pressure of ≥17% allowed detecting a fluid-induced increase in cardiac output of ≥15% with a sensitivity of 65[56-72]% and a specificity of 85[76-92]%. The area under the receiver operating characteristic curves for the fluid-induced changes in mean arterial pressure and in diastolic arterial pressure was significantly lower than for pulse pressure. In group 2, the introduction/increase of norepinephrine significantly increased cardiac output by 14% ± 18%. The changes in cardiac output induced by the introduction/increase in the dose of norepinephrine were correlated with the changes in pulse pressure and systolic arterial pressure (r = .21 and .29, respectively, p = .001) but to a significantly lesser extent than in group 1. Pulse pressure and systolic arterial

  8. Validation and application of single breath cardiac output determinations in man

    NASA Technical Reports Server (NTRS)

    Loeppky, J. A.; Fletcher, E. R.; Myhre, L. G.; Luft, U. C.

    1986-01-01

    The results of a procedure for estimating cardiac output by a single-breath technique (Qsb), obtained in healthy males during supine rest and during exercise on a bicycle ergometer, were compared with the results on cardiac output obtained by the direct Fick method (QF). The single breath maneuver consisted of a slow exhalation to near residual volume following an inspiration somewhat deeper than normal. The Qsb calculations incorporated an equation of the CO2 dissociation curve and a 'moving spline' sequential curve-fitting technique to calculate the instantaneous R from points on the original expirogram. The resulting linear regression equation indicated a 24-percent underestimation of QF by the Qsb technique. After applying a correction, the Qsb-QF relationship was improved. A subsequent study during upright rest and exercise to 80 percent of VO2(max) in 6 subjects indicated a close linear relationship between Qsb and VO2 for all 95 values obtained, with slope and intercept close to those in published studies in which invasive cardiac output measurements were used.

  9. Immediate effect on cardiac output of reversion to sinus rhythm from rapid arrhythmias.

    PubMed

    Wright, J S; Fabian, J; Epstein, E J

    1970-08-08

    Cardiac output was estimated immediately before and after conversion to sinus rhythm in nine patients with rapid arrhythmias. Conversion was by synchronized direct-current shock in eight patients, and by direct atrial wall stimulation in the other. In seven patients there was an immediate increase in cardiac output after restoration of sinus rhythm. The percentage increase in output was directly proportional to the rate of the arrhythmia immediately before conversion (r=0.91, P<0.01). The critical heart rate, above which an immediate increase in cardiac output might be expected on conversion to sinus rhythm, appeared in these patients to be about 160 beats per minute.

  10. Mechanisms Regulating the Cardiac Output Response to Cyanide Infusion, a Model of Hypoxia

    PubMed Central

    Liang, Chang-seng; Huckabee, William E.

    1973-01-01

    When tissue metabolic changes like those of hypoxia were induced by intra-aortic infusion of cyanide in dogs, cardiac output began to increase after 3 to 5 min, reached a peak (220% of the control value) at 15 min, and returned to control in 40 min. This pattern of cardiac output rise was not altered by vagotomy with or without atropine pretreatment. However, this cardiac output response could be differentiated into three phases by pretreating the animals with agents that block specific activities of the sympatho-adrenal system. First, ganglionic blockade produced by mecamylamine or sympathetic nerve blockade by bretylium abolished the middle phase of the cardiac output seen in the untreated animal, but early and late phases still could be discerned. Second, beta-adrenergic receptor blockade produced by propranolol shortened the total duration of the cardiac output rise by abolishing the late phase. Third, when given together, propranolol and mecamylamine (or bretylium) prevented most of the cardiac output rise that follows the early phase. When cyanide was given to splenectomized dogs, the duration of the cardiac output response was not shortened, but the response became biphasic, resembling that seen after chemical sympathectomy. A similar biphasic response of the cardiac output also resulted from splenic denervation; sham operation or nephrectomy had no effect on the monophasic pattern of the normal response. Splenic venous blood obtained from cyanide-treated dogs, when infused intraportally, caused an increase in cardiac output in recipient dogs; similar infusion of arterial blood had no effects. These results suggest that the cardiac output response to cyanide infusion consists of three components: an early phase, related neither to the autonomic nervous system nor to circulating catecholamines; a middle phase, caused by a nonadrenergic humoral substance released from the spleen by sympathetic stimulation; and a late phase, dependent upon adrenergic receptors

  11. Residual gravimetric method to measure nebulizer output.

    PubMed

    Vecellio None, Laurent; Grimbert, Daniel; Bordenave, Joelle; Benoit, Guy; Furet, Yves; Fauroux, Brigitte; Boissinot, Eric; De Monte, Michele; Lemarié, Etienne; Diot, Patrice

    2004-01-01

    The aim of this study was to assess a residual gravimetric method based on weighing dry filters to measure the aerosol output of nebulizers. This residual gravimetric method was compared to assay methods based on spectrophotometric measurement of terbutaline (Bricanyl, Astra Zeneca, France), high-performance liquid chromatography (HPLC) measurement of tobramycin (Tobi, Chiron, U.S.A.), and electrochemical measurements of NaF (as defined by the European standard). Two breath-enhanced jet nebulizers, one standard jet nebulizer, and one ultrasonic nebulizer were tested. Output produced by the residual gravimetric method was calculated by weighing the filters both before and after aerosol collection and by filter drying corrected by the proportion of drug contained in total solute mass. Output produced by the electrochemical, spectrophotometric, and HPLC methods was determined after assaying the drug extraction filter. The results demonstrated a strong correlation between the residual gravimetric method (x axis) and assay methods (y axis) in terms of drug mass output (y = 1.00 x -0.02, r(2) = 0.99, n = 27). We conclude that a residual gravimetric method based on dry filters, when validated for a particular agent, is an accurate way of measuring aerosol output.

  12. Cardiac Output and Performance during a Marathon Race in Middle-Aged Recreational Runners

    PubMed Central

    Billat, Véronique L.; Petot, Hélène; Landrain, Morgan; Meilland, Renaud; Koralsztein, Jean Pierre; Mille-Hamard, Laurence

    2012-01-01

    Purpose. Despite the increasing popularity of marathon running, there are no data on the responses of stroke volume (SV) and cardiac output (CO) to exercise in this context. We sought to establish whether marathon performance is associated with the ability to sustain high fractional use of maximal SV and CO (i.e, cardiac endurance) and/or CO, per meter (i.e., cardiac cost). Methods. We measured the SV, heart rate (HR), CO, and running speed of 14 recreational runners in an incremental, maximal laboratory test and then during a real marathon race (mean performance: 3 hr 30 min ± 45 min). Results. Our data revealed that HR, SV and CO were all in a high but submaximal steady state during the marathon (87.0 ± 1.6%, 77.2 ± 2.6%, and 68.7 ± 2.8% of maximal values, respectively). Marathon performance was inversely correlated with an upward drift in the CO/speed ratio (mL of CO × m−1) (r = −0.65, P < 0.01) and positively correlated with the runner's ability to complete the race at a high percentage of the speed at maximal SV (r = 0.83, P < 0.0002). Conclusion. Our results showed that marathon performance is inversely correlated with cardiac cost and positively correlated with cardiac endurance. The CO response could be a benchmark for race performance in recreational marathon runners. PMID:22645458

  13. Modified high-intensity interval training increases peak cardiac power output in patients with heart failure.

    PubMed

    Huang, Shu-Chun; Wong, Mei-Kuen; Lin, Pyng-Jing; Tsai, Feng-Chun; Fu, Tieh-cheng; Wen, Ming-Shien; Kuo, Chi-Tai; Wang, Jong-Shyan

    2014-09-01

    Although high-intensity interval aerobic training (HIT) effectively improves aerobic fitness, the risk of cardiac arrest transiently increases during strenuous physical exertion in patients with cardiovascular disease. For safety and efficacy concerns, this investigation explored the effect of a modified HIT (mHIT) on exertional ventilatory-hemodynamic efficiency in heart failure patients with reduced ejection fraction (HFREF). HFREF patients were prospectively assigned to two groups: mHIT and usual healthcare (UC). The former comprised supervised continuous aerobic training at ventilatory anaerobic threshold for 50 min/day, 3 days/week for 4 weeks, and then 3-min intervals at 40 and 80% VO₂ reserve for 50 min/day, 3 days/week for 8 weeks. The latter received optimal medical treatment only. Ventilatory and hemodynamic responses during exercise were measured before and after the intervention. Paired-t and repeated measures ANOVA with post hoc tests were adopted. Each group had an N of 33. The mHIT and UC group had matched baseline characteristics including health-promotion concept and behavior score. The mHIT for 12 weeks (1) increased VO₂, cardiac output, and notably, cardiac power output at peak workload (1,151 ± 573 vs. 1,306 ± 596 L/min/mmHg); (2) reduced V E/VO2 (32.4 ± 4.6 vs. 30.0 ± 4.0), breathing frequency, ventilation, and enhanced stroke volume compliance at identical submaximal intensity (50% peak workload at pre-intervention evaluation). No significant changes in ventilatory and hemodynamic responses to exercise were observed following the UC. The mHIT regimen improves peak cardiac pumping capacity with reducing cardiac after-load and simultaneously increases ventilation efficiency during exercise in patients with HFREF. Thereby, aerobic fitness is ameliorated.

  14. The influence of hemoglobin concentration on exercise cardiac output.

    PubMed

    Freedson, P S

    1981-05-01

    Two experiments were performed to study the cardiac output (Q) vs. hemoglobin concentration (Hb) relationship during constant load submaximum eexercise. The first experiment examined the relationship between submaximum exercise Q and Hb in 28 females. A correlation of r = -0.83 (P less than 0.05) was observed between Q and Hb during xercise at 88 W (mean Q = 11.04 l . min-1) and 118 W (mean Q = 13.10 l . min-1) (mean steady rate VO2 = 1.40 l . min-1 and 1.79 l . min-1, respectively). By removing the influence of stroke volume (SV) from Q (part correlation analyses), the relationship between Q and Hb is compromised (r = -0.29, P greater than 0.05, 88 W and r = -0.33, P greater than 0.05, 118 W). The second experiment compared the VO2 max and submaximum exercise (118 W) Q responses in six males before and after blood donation. Experimentally reducing Hb 18.6% (P less than 0.05) caused a 6.2% decrease (P less than 0.05) in VO2 max. Additionally, submaximum exercise Q increased 12% (P less than 0.05) 6 days following hemodilution., The Q remained elevated 11 days (10% higher, P less than 0.05) and 16 days (9% higher, P less than 0.05) post-blood donation and progressively returned to pre-donation levels by 21 days post-withdrawal. The higher Q's during submaximum exercise were ascribed primarily to an 8% (P less than 0.05) higher SV in comparison to pre-donation levels. collectively, the data from the two experiments indicate that individual differences in submaximum exercise Q are due, in part, to individual differences in Hb concentration. Furthermore, it is suggested that the stimulus for the SV-induced Q vs. Hb association is related to maintaining maximal myocardial efficiency.

  15. Influence of lung volume on the interaction between cardiac output and cerebrovascular regulation during extreme apnoea.

    PubMed

    Stembridge, Mike; Hoiland, Ryan L; Bain, Anthony R; Barak, Otto F; Drvis, Ivan; MacLeod, David B; MacLeod, Douglas M; Madden, Dennis; Batinic, Tonci; O'Donoghue, Peter; Shave, Rob; Dujic, Zeljko; Ainslie, Philip N

    2017-10-01

    What is the central question of this study? Does the reduction in cardiac output observed during extreme voluntary apnoea, secondary to high lung volume, result in a reduction in cerebral blood flow, perfusion pressure and oxygen delivery in a group of elite free divers? What is the main finding and its importance? High lung volumes reduce cardiac output and ventricular filling during extreme apnoea, but changes in cerebral blood flow are observed only transiently during the early stages of apnoea. This reveals that whilst cardiac output is important in regulating cerebral haemodynamics, the role of mean arterial pressure in restoring cerebral perfusion pressure is of greater significance to the regulation of cerebral blood flow. We investigated the role of lung volume-induced changes in cardiac output (Q̇) on cerebrovascular regulation during prolonged apnoea. Fifteen elite apnoea divers (one female; 185 ± 7 cm, 82 ± 12 kg, 29 ± 7 years old) attended the laboratory on two separate occasions and completed maximal breath-holds at total lung capacity (TLC) and functional residual capacity (FRC) to elicit disparate cardiovascular responses. Mean arterial pressure (MAP), internal jugular venous pressure and arterial blood gases were measured via cannulation. Global cerebral blood flow was quantified by ultrasound and cardiac output was quantified by via photoplethysmography. At FRC, stroke volume and Q̇ did not change from baseline (P > 0.05). In contrast, during the TLC trial stroke volume and Q̇ were decreased until 80 and 40% of apnoea, respectively (P < 0.05). During the TLC trial, global cerebral blood flow was significantly lower at 20%, but subsequently increased so that cerebral oxygen delivery was comparable to that during the FRC trial. Internal jugular venous pressure was significantly higher throughout the TLC trial in comparison to FRC. The MAP increased progressively in both trials but to a greater extent at TLC, resulting in a

  16. Optimisation of atrioventricular delay during exercise improves cardiac output in patients stabilised with cardiac resynchronisation therapy.

    PubMed

    Sun, Jing Ping; Lee, Alex Pui-Wai; Grimm, Richard A; Hung, Ming-Jui; Yang, Xing Sheng; Delurgio, David; Leon, Angel R; Merlino, John D; Yu, Cheuk-Man

    2012-01-01

    Atrioventricular (AV) delay in cardiac resynchronisation therapy (CRT) recipients are typically optimised at rest. However, there are limited data on the impact of exercise-induced changes in heart rate on the optimal AV delay and left ventricular function. The authors serially programmed AV delays in 41 CRT patients with intrinsic sinus rhythm at rest and during two stages of supine bicycle exercise with heart rates at 20 bpm (stage I) and 40 bpm (stage II) above baseline. The optimal AV delay during exercise was determined by the iterative method to maximise cardiac output using Doppler echocardiography. Results were compared to physiological change in PR intervals in 56 normal controls during treadmill exercise. The optimal AV delay was progressively shortened (p<0.05) with escalating exercise level (baseline: 123±26 ms vs. stage I: 102±24 ms vs stage II: 70±22 ms, p<0.05). AV delay optimisation led to a significantly higher cardiac output than without optimisation did during stage I (6.2±1.2 l/min vs. 5.2±1.2 l/min, p<0.001) and stage II (6.8±1.6 l/min vs. 5.9±1.3 l/min, p<0.001) exercise. A linear inverse relationship existed between optimal AV delays and heart rates in CRT patients (AV delay=241-1.61×heart rate, R2=0.639, p<0.001) and healthy controls (R2=0.646, p<0.001), but the slope of regression was significantly steeper in CRT patients (p<0.001). Haemodynamically optimal AV delay shortened progressively with increasing heart rate during exercise, which suggests the need for programming of rate-adaptive AV delay in CRT recipients.

  17. Cardiac output assessment using oxygen consumption estimated from the left ventricular pressure-volume area.

    PubMed

    Negroni, Jorge A; Lascano, Elena C; Bertolotti, Alejandro M; Gómez, Carmen B; Rodríguez Correa, Carlos A; Favaloro, Roberto R

    2010-01-01

    Use of a majority of structural variables (age, sex, height) to estimate oxygen consumption in the calculation of cardiac output (CO) by the Fick principle does not account for changes in physiological conditions. To improve this limitation, oxygen consumption was estimated based on the left ventricular pressure-volume area. A pilot study with 10 patients undergoing right cardiac catheterization showed that this approach was successful to estimate CO (r=0,73, vs. thermodilution measured CO). Further essays changing end-diastolic-volume in the pressure-volume area formula by body weight or body surface area showed that this last yielded the best correlation with the thermodilution measured CO (slope=1, ordinate =0.01 and r=0.93). These preliminary results indicate that use of a formula originated from the pressure-volume-area concept is a good alternative to estimate oxygen consumption for CO calculation.

  18. Continuous noninvasive cardiac output determination using the CNAP system: evaluation of a cardiac output algorithm for the analysis of volume clamp method-derived pulse contour.

    PubMed

    Wagner, Julia Y; Grond, Julian; Fortin, Jürgen; Negulescu, Ileana; Schöfthaler, Miriam; Saugel, Bernd

    2016-08-01

    The CNAP system (CNSystems Medizintechnik AG, Graz, Austria) provides noninvasive continuous arterial pressure measurements by using the volume clamp method. Recently, an algorithm for the determination of cardiac output by pulse contour analysis of the arterial waveform recorded with the CNAP system became available. We evaluated the agreement of the continuous noninvasive cardiac output (CNCO) measurements by CNAP in comparison with cardiac output measurements invasively obtained using transpulmonary thermodilution (TDCO). In this proof-of-concept analysis we studied 38 intensive care unit patients from a previously set up database containing CNAP-derived arterial pressure data and TDCO values obtained with the PiCCO system (Pulsion Medical Systems SE, Feldkirchen, Germany). We applied the new CNCO algorithm retrospectively to the arterial pressure waveforms recorded with CNAP and compared CNCO with the corresponding TDCO values (criterion standard). Analyses were performed separately for (1) CNCO calibrated to the first TDCO (CNCO-cal) and (2) CNCO autocalibrated to biometric patient data (CNCO-auto). We did not perform an analysis of trending capabilities because the patients were hemodynamically stable. The median age and APACHE II score of the 22 male and 16 female patients was 63 years and 18 points, respectively. 18 % were mechanically ventilated and in 29 % vasopressors were administered. Mean ± standard deviation for CNCO-cal, CNCO-auto, and TDCO was 8.1 ± 2.7, 6.4 ± 1.9, and 7.8 ± 2.4 L/min, respectively. For CNCO-cal versus TDCO, Bland-Altman analysis demonstrated a mean difference of +0.2 L/min (standard deviation 1.0 L/min; 95 % limits of agreement -1.7 to +2.2 L/min, percentage error 25 %). For CNCO-auto versus TDCO, the mean difference was -1.4 L/min (standard deviation 1.8 L/min; 95 % limits of agreement -4.9 to +2.1 L/min, percentage error 45 %). This pilot analysis shows that CNCO determination is feasible in critically

  19. Arterial pulse cardiac output agreement with thermodilution in patients in hyperdynamic conditions.

    PubMed

    Della Rocca, Giorgio; Costa, Maria Gabriella; Chiarandini, Paolo; Bertossi, Gaia; Lugano, Manuela; Pompei, Livia; Coccia, Cecilia; Sainz-Barriga, Mauricio; Pietropaoli, Paolo

    2008-10-01

    This study aimed to compare continuous cardiac output (CCO) obtained using the arterial pulse wave (APCO) measurement with a simultaneous measurement of the intermittent cardiac output (ICO) and CCO obtained with a pulmonary artery catheter (PAC) in liver transplant patients. A prospective, single-center evaluation. A university hospital intensive care unit. Eighteen patients after liver transplantation. Pulmonary artery catheters were placed in all patients, and ICO and CCO were determined using thermodilution. APCO measurements were made with the Vigileo System (Edwards Lifesciences, Irvine, CA). The authors obtained 126 data pairs of ICO and APCO and 864 pairs of CCO and APCO. ICO data were collected after intensive care unit admission and every 8 hours until the 48th postoperative hour. CCO and APCO data were collected every hour from admission until the 48th postoperative hour. Bias and precision were 0.95 +/- 1.41 L/min for ICO versus APCO and 1.29 +/- 1.28 L/min for CCO and APCO. Bias and precision for cardiac output (CO) data pairs less than 8 L/min were 0.32 +/- 1.14 L/min between ICO and APCO and 0.71 +/- 0.98 L/min between CCO and APCO. For CO data pairs higher than 8 L/min, bias and precision were 1.79 +/- 1.54 L/min between ICO and APCO and 2.25 +/- 1.14 L/min between CCO and APCO. APCO enables the assessment of CO with clinically acceptable bias and precision. At higher CO levels, APCO underestimates PAC measurements and it is not as reliable as thermodilution in hyperdynamic liver transplant patients.

  20. Evaluation of cardiac output from a tidally ventilated homogeneous lung model.

    PubMed

    Benallal, Habib; Beck, Kenneth C; Johnson, Bruce D; Busso, Thierry

    2005-10-01

    We used the direct Fick measurements to validate a method for estimating cardiac output by iteratively fitting VCO(2) at the mouth to lung model values. This model was run using a series of 50, 30 and 10 breaths to test sensitivity to number of breaths used for fitting. The lung was treated as a catenary two-compartment lung model consisting of a dead space compartment connected with a single alveolar space compartment, perfused with constant pulmonary blood flow. The implemented mathematical modeling described variations in O(2) and CO(2) compartmental fractions and alveolar volume. This model also included pulmonary capillary gas exchange. Experimental data were collected from measurements performed on six healthy subjects at rest and during 20, 40, 60 and 85-90% of peak V(O)(2). The correlation between the two methods was highest and the average agreement between the methods was best using 50 breaths R = 095; P < 0.0001; Q(model) = 1.1Q(Fick) - 2.3). The mean difference and lower to upper limits of agreement between measured and estimated data were 0.7 l/min (-2.7 to 4.1 l/min) for cardiac output; -0.9 ml/100 ml (-1.3 to -0.5 ml/100 ml) for arterial O(2) content; -0.8 ml/100 ml (-3.8 to 2.2 ml/100 ml) for mixed venous O(2) content and -0.1 ml/100 ml (-2.9 to 2.7 ml/100 ml) for arteriovenous difference O(2) content. The cardiac output estimated by the lung model was in good agreement with the direct Fick measurements in young healthy subjects.

  1. Increased cardiac output and microvascular blood flow during mild hemoconcentration in hamster window model.

    PubMed

    Martini, Judith; Tsai, Amy G; Cabrales, Pedro; Johnson, Paul C; Intaglietta, Marcos

    2006-07-01

    The effect of small hematocrit (Hct) increases on cardiac index (cardiac output/body wt) and oxygen release to the microcirculation was investigated in the awake hamster window chamber model by means of exchange transfusions of homologous packed red blood cells. Increasing Hct between 8 and 13% from baseline increased cardiac index by 5-31% from baseline (P < 0.05) and significantly lowered systemic blood pressure (P < 0.05). The relationship between Hct and cardiac index is described by a second-order polynomial (R2 = 0.84; P < 0.05) showing that Hct increases up to 20% from baseline increase cardiac index, whereas increases over 20% from baseline decrease cardiac index. Combining this data with measurements of blood pressure allowed to determine total peripheral vascular resistance, which was a minimum at 8-13% Hct increase and was described by a second-order polynomial (R2 = 0.83; P < 0.05). Oxygen measurements in arterioles, venules, and the tissue at 8-13% Hct increase were identical to control; thus, as a consequence of increased flow and oxygen-carrying capacity, oxygen delivery and extraction increased, but the change was not statistically significant. Previous results with the same model showed that the observed effects are related to shear stress-mediated release of nitric oxide, an effect that should be also present in the heart microcirculation, leading to increased blood flow, myocardial oxygen consumption, and contractility. We conclude that a minimum viscosity level is necessary for generating the shear stress required for maintaining normal cardiovascular function.

  2. Defence Output Measures: An Economics Perspective

    DTIC Science & Technology

    2011-11-01

    Des budgets de la comptabilité des intrants, des extrants, de la gestion et des ressources ont été utilisés comme mesures relatives aux résultats...This Report focused on financial management information (e.g. management of stocks and assets)) and made no mention of defence output measures. At

  3. [Impedance cardiography, a method to evaluate quantitatively cardiac output? Comparison with the Fick principle (author's transl)].

    PubMed

    Betz, R; Bastanier, C K; Mocellin, R

    1977-01-01

    In 36 children without shunts nearly 280 electrical impedance measurements were carried out in order to estimate the accuracy of the impedance cardiography as a means of calculating output. During evaluation up to 22 combinations of test conditions and possibilities of evaluation per child were tested. As a reference method the Fick Principle was used. The reproducibility of impedance measurements showed itself to be high, but no agreement of the results by impedance cardigraphy and corresponding values by the Fick method could be found. Some reasons give rise to suppose that impedance cardiography only reflects changes in the intrathoracic fluid level occurring during heart action from which because of formal reasons no interference should be drawn about the original cardiac output. Besides physical arguments tell against the possibility of picking up these volume-changes quantitatively by analyzing transthoracic electrical impedance.

  4. [Determination of cardiac output under PEEP-respiration with the "NCCOM 3" non-invasive bioimpedence monitor in comparison with the thermodilution method. A study in anesthetized dogs].

    PubMed

    Weber, J; Heidelmeyer, C F; Kubatz, E; Brückner, J B

    1986-12-01

    A new noninvasive cardiac output (CO) computer ("NCCOM 3") based on the bioimpedance principle was compared to a CO computer based on standard thermodilution measurements. Simultaneous measurements were made on dogs who were ventilated with or without positive end expiratory pressure (PEEP). There was no correlation of cardiac output measurements with the two methods (r = 0.10, n = 60). Comparing only measurements without PEEP yielded r = 0.41. Thermodilution measurements showed the well-known decline in cardiac output during PEEP, whereas the bioimpedance device recorded an increase in cardiac output. These differences were statistically significant. We conclude that the NCCOM 3 cannot at present replace the invasive standard methods of CO measurement in ventilated patients. A lack of differentiation of circulatory effects, thoracic gas volume, and intrathoracic fluid content is the most likely cause of the discrepancies seen.

  5. High flow variant postural orthostatic tachycardia syndrome amplifies the cardiac output response to exercise in adolescents.

    PubMed

    Pianosi, Paolo T; Goodloe, Adele H; Soma, David; Parker, Ken O; Brands, Chad K; Fischer, Philip R

    2014-08-01

    Postural orthostatic tachycardia syndrome (POTS) is characterized by chronic fatigue and dizziness and affected individuals by definition have orthostatic intolerance and tachycardia. There is considerable overlap of symptoms in patients with POTS and chronic fatigue syndrome (CFS), prompting speculation that POTS is akin to a deconditioned state. We previously showed that adolescents with postural orthostatic tachycardia syndrome (POTS) have excessive heart rate (HR) during, and slower HR recovery after, exercise - hallmarks of deconditioning. We also noted exaggerated cardiac output during exercise which led us to hypothesize that tachycardia could be a manifestation of a high output state rather than a consequence of deconditioning. We audited records of adolescents presenting with long-standing history of any mix of fatigue, dizziness, nausea, who underwent both head-up tilt table test and maximal exercise testing with measurement of cardiac output at rest plus 2-3 levels of exercise, and determined the cardiac output () versus oxygen uptake () relationship. Subjects with chronic fatigue were diagnosed with POTS if their HR rose ≥40 beat·min(-1) with head-up tilt. Among 107 POTS patients the distribution of slopes for the , relationship was skewed toward higher slopes but showed two peaks with a split at ~7.0 L·min(-1) per L·min(-1), designated as normal (5.08 ± 1.17, N = 66) and hyperkinetic (8.99 ± 1.31, N = 41) subgroups. In contrast, cardiac output rose appropriately with in 141 patients with chronic fatigue but without POTS, exhibiting a normal distribution and an average slope of 6.10 ± 2.09 L·min(-1) per L·min(-1). Mean arterial blood pressure and pulse pressure from rest to exercise rose similarly in both groups. We conclude that 40% of POTS adolescents demonstrate a hyperkinetic circulation during exercise. We attribute this to failure of normal regional vasoconstriction during exercise, such that patients must increase flow through an

  6. Cardiac output and vasodilation in the vasovagal response: An analysis of the classic papers.

    PubMed

    Wieling, Wouter; Jardine, David L; de Lange, Frederik J; Brignole, Michele; Nielsen, Henning B; Stewart, Julian; Sutton, Richard

    2016-03-01

    The simple faint is secondary to hypotension and bradycardia resulting in transient loss of consciousness. According to Ohm's law applied to the circulation, BP = SVR × CO, hypotension can result from a decrease in systemic vascular resistance (SVR), cardiac output (CO), or both. It is important to understand that when blood pressure (BP) is falling, SVR and CO do not change reciprocally as they do in the steady state. In 1932, Lewis, assuming that decreased SVR alone accounted for hypotension, defined "the vasovagal response" along pathophysiologic lines to denote the association of vasodilation with vagal-induced bradycardia in simple faint. Studies performed by Barcroft and Sharpey-Schafer between 1940 and 1950 used volume-based plethysmography to demonstrate major forearm vasodilation during extreme hypotension and concluded that the main mechanism for hypotension was vasodilation. Plethysmographic measurements were intermittent and not frequent enough to capture rapid changes in blood flow during progressive hypotension. However, later investigations by Weissler, Murray, and Stevens performed between 1950 and 1970 used invasive beat-to-beat BP measurements and more frequent measurements of CO using the Fick principle. They demonstrated that CO significantly fell before syncope, and little vasodilation occurred until very late in the vasovagal reaction Thus, since the 1970s, decreasing cardiac output rather than vasodilation has been regarded as the principal mechanism for the hypotension of vasovagal syncope. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

  7. Oxygen uptake kinetics at work onset: role of cardiac output and of phosphocreatine breakdown.

    PubMed

    Francescato, M P; Cettolo, V; di Prampero, P E

    2013-01-15

    The hypothesis that variability in individual's cardiac output response affects the kinetics of pulmonary O₂ uptake (VO₂) was tested by investigating the time constants of cardiac output (Q) adjustment (τ(Q)), of PCr splitting (τ(PCr)), and of phase II pulmonary O₂ uptake (τ(VO₂)) in eight volunteers. VO₂, Q, and gastrocnemius [PCr] (by (31)P-MRS) were measured at rest and during low intensity two-legged exercise. Steady state VO₂ and Q increased (ΔVO₂(s) = 182 ± 58 mL min⁻¹; ΔQ = 1.3 ± 0.4 L min⁻¹), whereas [PCr] decreased significantly (21 ± 8%). τ(VO₂), τ(PCr) and τ(Q) were significantly different from each other (38.3 ± 4.0, 23.9 ± 2.5, 11.6 ± 4.6 s, respectively; p<0.001). τ(PCr) assumed to be equal to the time constant of VO₂ at the muscle level (τ(mVO₂)), was not related to τ(Q), whereas τ(VO₂) and τ(Q) were significantly related (p<0.05) as were τ(VO₂) and τ(PCr) (p<0.05). Venous blood O₂ stores changes, as determined from arterio-to-mixed-venous O₂ content, were essentially equal to those estimated as (τ(VO₂)-τ(PCr))·ΔVO₂(s). This suggests that cardiac output responses affect O₂ stores utilization and hence τ(VO₂) : thus τ(VO₂) is not necessarily a good estimate of τ(mVO₂).

  8. A new non-invasive continuous cardiac output trend solely utilizing routine cardiovascular monitors.

    PubMed

    Ishihara, Hironori; Okawa, Hirobumi; Tanabe, Ken; Tsubo, Toshihito; Sugo, Yoshihiro; Akiyama, Takeshi; Takeda, Sunao

    2004-12-01

    Three of the us developed a new non-invasive continuous cardiac output (CCO) measurement method utilizing routine clinical monitors based on the pulse-contour analysis combined with pulse wave transit time (PWTT). Using pulmonary artery catheter (CCOpa), we compared this estimated CCO (esCO) with the thermodilution CCO early after cardiac surgery, and tested whether the esCO method has potential of being an alternative measure of CCO. Thirty-six patients without continued arrhythmias were studied. esCO was computed using electrocardiogram (ECG) monitor, arterial pressure monitor and pulse-oximetry system. Both sets of data (esCO and CCOpa), by averaging the results of the preceding 10 min, were compared at 30-min intervals throughout the 15.8 +/- 3.3 h (S.D.) of study. Bland-Altman plots and correlation analysis were used for statistical comparison. A total of 981 paired sets of data (89.9%) among 1093 measurements were compared in the absence of displacement of either pulse-oximetry or ECG probes and/or inaccurate detection of R wave. The difference between esCO and CCOpa results was -0.06 +/- 0.82 L/min (S.D.), and there was a linear correlation between them (r = 0.80, p < 0.0001). The difference between them was 0.00 +/- 0.48 L/min at the first 1 h, which remained unchanged throughout 20 h after the start of measurement. The results demonstrate that esCO has a close correlation with the CCOpa, even though the two methods are not interchangeable. The results suggest that esCO method has potential of being an alternative non-invasive cardiac output trend, unless there are apparent arrhythmias.

  9. Cerebral oxygen saturation and cardiac output during anaesthesia in sitting position for neurosurgical procedures: a prospective observational study.

    PubMed

    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.

  10. NOTE: Increasing cardiac output and decreasing oxygenation sequence in pump twins of acardiac twin pregnancies

    NASA Astrophysics Data System (ADS)

    van Gemert, Martin J. C.; Umur, Asli; van den Wijngaard, Jeroen P. H. M.; Van Bavel, Ed; Vandenbussche, Frank P. H. A.; Nikkels, Peter G. J.

    2005-02-01

    An acardiac twin pregnancy is a rare but serious complication of monochorionic twinning and consists of an acardiac twin and a pump twin. The acardiac twin is a severely malformed fetus that lacks most organs, particularly a heart, but grows during pregnancy because it is perfused by the developmentally normal pump twin via a set of arterioarterial and venovenous placental anastomoses. Pump twins die intrauterine or neonatally in about 50% of the cases. Because the effects of an acardiac mass on the pump twin's development are incompletely known, methods for outcome prognosis are currently not available. We sought to derive simple relations for the pump twin's excess cardiac output and decreased oxygenation and to use available clinical cases for a preliminary test of the model. As a method, we used a theoretical flow model to represent the fetoplacental circulation of an acardiac twin pregnancy and estimated blood deoxygenation and reoxygenation following perfusion of the two bodies and placentas, respectively. The results show the pump twin's excess cardiac output and decrease of venous oxygen saturation to depend on the ratio of pump twin to acardiac twin umbilical blood flow, whose ratio can be measured by ultrasonography. The clinical cases show a decreasing umbilical flow ratio with gestation. In conclusion, prospective serial study is necessary to test whether measurement of umbilical flow ratios allows monitoring the pump twin's pathophysiologic development, possibly resulting in a guideline for prognosis of pump twin survival.

  11. Measuring cardiac waste: the premier cardiac waste measures.

    PubMed

    Lowe, Timothy J; Partovian, Chohreh; Kroch, Eugene; Martin, John; Bankowitz, Richard

    2014-01-01

    The authors developed 8 measures of waste associated with cardiac procedures to assist hospitals in comparing their performance with peer facilities. Measure selection was based on review of the research literature, clinical guidelines, and consultation with key stakeholders. Development and validation used the data from 261 hospitals in a split-sample design. Measures were risk adjusted using Premier's CareScience methodologies or mean peer value based on Medicare Severity Diagnosis-Related Group assignment. High variability was found in resource utilization across facilities. Validation of the measures using item-to-total correlations (range = 0.27-0.78), Cronbach α (.88), and Spearman rank correlation (0.92) showed high reliability and discriminatory power. Because of the level of variability observed among hospitals, this study suggests that there is opportunity for facilities to design successful waste reduction programs targeting cardiac-device procedures.

  12. Quantification of the impaired cardiac output response to exercise in heart failure: application of a non-invasive device.

    PubMed

    Myers, Jonathan; Gujja, Pradeep; Neelagaru, Suresh; Hsu, Leon; Burkhoff, Daniel

    2009-01-01

    An impaired cardiac output (CO) response to exercise is a hallmark of chronic heart failure (CHF), and the degree to which CO is impaired is related to the severity of CHF and prognosis. However, practical methods for obtaining cardiac output during exercise are lacking, and what constitutes and impaired response is unclear. Forty six CHF patients and 13 normal subjects underwent cardiopulmonary exercise testing (CPX) while CO and other hemodynamic measurements at rest and during exercise were obtained using a novel, non-invasive, bioreactance device based on assessment of relative phase shifts of electric currents injected across the thorax, heart rate and ventricular ejection time. An abnormal cardiac output response to exercise was defined as achieving ≤ 95% of the confidence limits of the slope of the relationship between CO and oxygen uptake (VO2). An impaired CO slope identified patients with more severe CHF as evidenced by a lower peak VO2, lower peak CO, heightened VE/VCO2 slope, and lower oxygen uptake efficiency slope. CO can be estimated during exercise using a novel bioreactance technique; patients with an impaired response to exercise exhibit reduced exercise capacity and inefficient ventilation typical of more severe CHF. Non- invasive measurement of cardiac performance in response to exercise provides a simple method of identifying patients with more severe CHF and may complement the CPX in identifying CHF patients at high risk. Key pointsNon-invasive measurement of cardiac output during exercise is feasible in patients with heart failure.Impairment in the CO response to exercise identifies heart failure patients with more severe disease, lower exercise capacity and inefficient ventilation.Non-invasive measurement of cardiac performance during exercise has potentially important applications for the functional and prognostic assessment of patients with heart failure.

  13. Application of bioreactance for cardiac output assessment during exercise in healthy individuals.

    PubMed

    Elliott, Adrian; Hull, James H; Nunan, David; Jakovljevic, Djordje G; Brodie, David; Ansley, Lesley

    2010-07-01

    In patients with cardiac failure, bioreactance-based cardiac output (CO) monitoring provides a valid non-invasive method for assessing cardiac performance during exercise. The purpose of this study was to evaluate the efficacy of this technique during strenuous exercise in healthy, trained individuals. Fourteen recreational cyclists, mean (SD) age of 34 (8) years and relative peak oxygen uptake of (VO(2)) 56 (6) ml kg(-1) min(-1), underwent incremental maximal exercise testing, whilst CO was recorded continuously using a novel bioreactance-based device (CO(bio)). The CO(bio) was evaluated against relationship with VO(2), theoretical calculation of arterial-venous oxygen difference (C(a - v) O(2)) and level of agreement with an inert gas rebreathing method (CO(rb)) using a Bland-Altman plot. Bioreactance-based CO measurement was practical and straightforward in application, although there was intermittent loss of electrocardiograph signal at high-intensity exercise. At rest and during exercise, CO(bio) was strongly correlated with VO(2) (r = 0.84; P < 0.001), however, there was evidence of systematic bias with CO(bio) providing lower values than CO(rb); mean bias (limits of agreement) -19% (14.6 to -53%). Likewise, calculated (C(a - v) O(2)) was greater when determined using CO(bio) than CO(rb) (P < 0.001), although both devices provided values in excess of those reported in invasive studies. Bioreactance-based determination of CO provides a pragmatic approach to the continuous assessment of cardiac performance during strenuous exercise in trained individuals. Our findings, however, suggest that further work is needed to refine the key measurement determinants of CO using this device to improve measurement accuracy in this setting.

  14. Effect of norepinephrine dosage and calibration frequency on accuracy of pulse contour-derived cardiac output

    PubMed Central

    2011-01-01

    Introduction Continuous cardiac output monitoring is used for early detection of hemodynamic instability and guidance of therapy in critically ill patients. Recently, the accuracy of pulse contour-derived cardiac output (PCCO) has been questioned in different clinical situations. In this study, we examined agreement between PCCO and transcardiopulmonary thermodilution cardiac output (COTCP) in critically ill patients, with special emphasis on norepinephrine (NE) administration and the time interval between calibrations. Methods This prospective, observational study was performed with a sample of 73 patients (mean age, 63 ± 13 years) requiring invasive hemodynamic monitoring on a non-cardiac surgery intensive care unit. PCCO was recorded immediately before calibration by COTCP. Bland-Altman analysis was performed on data subsets comparing agreement between PCCO and COTCP according to NE dosage and the time interval between calibrations up to 24 hours. Further, central artery stiffness was calculated on the basis of the pulse pressure to stroke volume relationship. Results A total of 330 data pairs were analyzed. For all data pairs, the mean COTCP (±SD) was 8.2 ± 2.0 L/min. PCCO had a mean bias of 0.16 L/min with limits of agreement of -2.81 to 3.15 L/min (percentage error, 38%) when compared to COTCP. Whereas the bias between PCCO and COTCP was not significantly different between NE dosage categories or categories of time elapsed between calibrations, interchangeability (percentage error <30%) between methods was present only in the high NE dosage subgroup (≥0.1 μg/kg/min), as the percentage errors were 40%, 47% and 28% in the no NE, NE < 0.1 and NE ≥ 0.1 μg/kg/min subgroups, respectively. PCCO was not interchangeable with COTCP in subgroups of different calibration intervals. The high NE dosage group showed significantly increased central artery stiffness. Conclusions This study shows that NE dosage, but not the time interval between calibrations, has an

  15. The precision of a special purpose analog computer in clinical cardiac output determination.

    PubMed Central

    Sullivan, F J; Mroz, E A; Miller, R E

    1975-01-01

    Three hundred dye-dilution curves taken during our first year of clinical experience with the Waters CO-4 cardiac output computer were analyzed to estimate the errors involved in its use. Provided that calibration is accurate and 5.0 mg of dye are injected for each curve, then the percentage standard deviation of measurement using this computer is about 8.7%. Included in this are the errors inherent in the computer, errors due to baseline drift, errors in the injection of dye and acutal variation of cardiac output over a series of successive determinations. The size of this error is comparable to that involved in manual calculation. The mean value of five successive curves will be within 10% of the real value in 99 cases out of 100. Advances in methodology and equipment are discussed which make calibration simpler and more accurate, and which should also improve the quality of computer determination. A list of suggestions is given to minimize the errors involved in the clinical use of this equipment. Images Fig. 4. PMID:1089394

  16. [Determination of cardiac output by Doppler ultrasonics. Principle, techniques and limitations].

    PubMed

    Tribouilloy, C; Caze, F; Rey, J L; Marek, A; Quere, J P; Dufosse, H; Lesbre, J P

    1991-10-01

    The development of quantitative applications of Doppler ultrasound for the measurement of cardiac output was a lengthy and difficult process. These applications call for rigor of the part of the ultrasound cardiographer and a sufficiently echoic patient. Numerous studies have demonstrated the reliability of Doppler ultrasound in determining aortic flow. A high degree of consensus has emerged for measuring aortic areas and velocities at the ring. Doppler ultrasound quantification of the pulmonary flow has been validated in children. In adults, measurement of the pulmonary ring is often difficult and may lead to major errors in the estimation of the flow rates. The determination of mitral flow is also possible, either at the ring or at the tip of the mitral funnel. A few publications highlight the value of Doppler ultrasound in evaluation of tricuspid flow, however, these results require confirmation.

  17. A right ventricular pressure waveform based pulse contour cardiac output algorithm in canines.

    PubMed

    Karamanoglu, Mustafa; Bennett, Tom D

    2006-09-01

    Tracking changes in stroke volume or cardiac output (CO) can be useful in the diagnosis and treatment of various cardiac illnesses. Existing arterial pressure waveform based pulse contour CO algorithms perform poorly during altered systemic hemodynamics. In this study, a right ventricular pressure waveform based pulse contour CO algorithm was developed to estimate the amplitude and duration of a hypothetical triangular flow waveform in the pulmonary artery. This algorithm was tested against gold standard blood flow measurements in ten canines during acute perturbations to preload (inferior vena caval occlusion (IVCO), rapid saline infusion), afterload (descending aortic occlusion (DAO), serotonin, angiotensin II, sodium nitroprusside infusion), and cardiac contractility (dobutamine and propranolol infusion). The algorithm correctly predicted the changes in CO (r2 = 0.82) that varied from - 45 to 31% of the baseline levels. To explain this finding both the pulmonary arterial (PA) and the ascending aortic (AA) input impedances were modeled as three element windkessels. In the AA the peripheral resistance (from - 61 to 191%), characteristic impedance (from - 59 to 20%) and total arterial compliance (from - 49 to 34%) varied significantly with these perturbations. In contrast, these parameters in the PA changed little. In particular, except serotonin infusion, the characteristic impedance of the PA deviated only 6% (SD/mean) from baseline values. This suggests right ventricular pressure waveform based estimate of CO is possible during acute changes in left ventricular hemodynamics.

  18. Effects of acute hypoxia at moderate altitude on stroke volume and cardiac output during exercise.

    PubMed

    Fukuda, Taira; Maegawa, Taketeru; Matsumoto, Akihiro; Komatsu, Yutaka; Nakajima, Toshiaki; Nagai, Ryozo; Kawahara, Takashi

    2010-05-01

    It has been unclear how acute hypoxia at moderate altitude affects stroke volume (SV), an index of cardiac function, during exercise. The present study was conducted to reveal whether acute normobaric hypoxia might alter SV during exercise.Nine healthy male subjects performed maximal exercise testing under normobaric normoxic, and normobaric hypoxic conditions (O(2): 14.4%) in a randomized order. A novel thoracic impedance method was used to continuously measure SV and cardiac output (CO) during exercise. Acute hypoxia decreased maximal work rate (hypoxia; 247 + or - 6 [SE] versus normoxia; 267 + or - 8 W, P < 0.005) and VO(2) max (hypoxia; 2761 + or - 99 versus normoxia; 3039 + or - 133 mL/min, P < 0.005). Under hypoxic conditions, SV and CO at maximal exercise decreased (SV: hypoxia; 145 + or - 11 versus normoxia; 163 + or - 11 mL, P < 0.05, CO: hypoxia; 26.7 + or - 2.1 versus normoxia; 30.2 + or - 1.8 L/min, P < 0.05). In acute hypoxia, SV during submaximal exercise at identical work rate decreased. Furthermore, in hypoxia, 4 of 9 subjects attained their highest SV at maximal exercise, while in normoxia, 8 of 9 subjects did.Acute normobaric hypoxia attenuated the increment of SV and CO during exercise, and SV reached a plateau earlier under hypoxia than in normoxia. Cardiac function during exercise at this level of acute normobaric hypoxia might be attenuated.

  19. [Estimation of cardiac output by first-pass data with technetium-99m-labeled myocardial perfusion imaging agent].

    PubMed

    Muramori, A; Taki, J; Kinuya, S; Miyazaki, Y; Nakajima, K; Matsunari, I; Tonami, N

    1998-06-01

    Technetium-99m-tetrofosmin, a myocardial perfusion imaging agent was used for estimation of cardiac output by means of first-pass radionuclide angiography performed in the anterior projection. Region of interests (ROIs) were assigned over right ventricle, left ventricle and whole chest, and time activity curves (TACs) were obtained. Cardiac output indices (COIs) were calculated by the following equation; COI = p3/2. Qc/[symbol: see text] A(s)ds, where p = number of pixels of the ventricular ROI, Qc = the peak count rate of the TAC obtained from the whole chest's ROI and [symbol: see text] A(s)ds = the area under ventricular TAC. The COI (y) determined by ROI over the left ventricle yield the best correlation with the cardiac output by conventional radionuclide method (x) (y = 0.0381x + 6.22, r = 0.828, n = 48, p < 0.001). In conclusion, cardiac output can be easily measured with first pass data using myocardial perfusion imaging agent.

  20. Increased cardiac output elicits higher V̇O2max in response to self-paced exercise.

    PubMed

    Astorino, Todd Anthony; McMillan, David William; Edmunds, Ross Montgomery; Sanchez, Eduardo

    2015-03-01

    Recently, a self-paced protocol demonstrated higher maximal oxygen uptake versus the traditional ramp protocol. The primary aim of the current study was to further explore potential differences in maximal oxygen uptake between the ramp and self-paced protocols using simultaneous measurement of cardiac output. Active men and women of various fitness levels (N = 30, mean age = 26.0 ± 5.0 years) completed 3 graded exercise tests separated by a minimum of 48 h. Participants initially completed progressive ramp exercise to exhaustion to determine maximal oxygen uptake followed by a verification test to confirm maximal oxygen uptake attainment. Over the next 2 sessions, they performed a self-paced and an additional ramp protocol. During exercise, gas exchange data were obtained using indirect calorimetry, and thoracic impedance was utilized to estimate hemodynamic function (stroke volume and cardiac output). One-way ANOVA with repeated measures was used to determine differences in maximal oxygen uptake and cardiac output between ramp and self-paced testing. Results demonstrated lower (p < 0.001) maximal oxygen uptake via the ramp (47.2 ± 10.2 mL·kg(-1)·min(-1)) versus the self-paced (50.2 ± 9.6 mL·kg(-1)·min(-1)) protocol, with no interaction (p = 0.06) seen for fitness level. Maximal heart rate and cardiac output (p = 0.02) were higher in the self-paced protocol versus ramp exercise. In conclusion, data show that the traditional ramp protocol may underestimate maximal oxygen uptake compared with a newly developed self-paced protocol, with a greater cardiac output potentially responsible for this outcome.

  1. The feasibility and applications of non-invasive cardiac output monitoring, thromboelastography and transit-time flow measurement in living-related renal transplantation surgery: results of a prospective pilot observational study

    PubMed Central

    2014-01-01

    Introduction Delayed graft function (DGF) remains a significant and detrimental postoperative phenomenon following living-related renal allograft transplantation, with a published incidence of up to 15%. Early therapeutic vasodilatory interventions have been shown to improve DGF, and modifications to immunosuppressive regimens may subsequently lessen its impact. This pilot study assesses the potential applicability of perioperative non-invasive cardiac output monitoring (NICOM), transit-time flow monitoring (TTFM) of the transplant renal artery and pre-/perioperative thromboelastography (TEG) in the early prediction of DGF and perioperative complications. Methods Ten consecutive living-related renal allograft recipients were studied. Non-invasive cardiac output monitoring commenced immediately following induction of anaesthesia and was maintained throughout the perioperative period. Doppler-based TTFM was performed during natural haemostatic pauses in the transplant surgery: immediately following graft reperfusion and following ureteric implantation. Central venous blood sampling for TEG was performed following induction of anaesthesia and during abdominal closure. Results A single incidence of DGF was seen within the studied cohort and one intra-operative (thrombotic) complication noted. NICOM confirmed a predictable trend of increased cardiac index (CI) following allograft reperfusion (mean CI - clamped: 3.17 ± 0.29 L/min/m2, post-reperfusion: 3.50 ± 0.35 L/min/m2; P < 0.05) mediated by a significant reduction in total peripheral resistance. Reduced TTFM at the point of allograft reperfusion (227 ml/min c.f. mean; 411 ml/min (95% CI: 358 to 465)) was identified in a subject who experienced intra-operative transplant renal artery thrombosis. TEG data exhibited significant reductions in clot lysis (LY30 (%): pre-op: 1.0 (0.29 to 1.71), post reperfusion 0.33 (0.15 to 0.80); P = 0.02) and a trend towards increased clot initiation following

  2. Reference values for total blood volume and cardiac output in humans

    SciTech Connect

    Williams, L.R.

    1994-09-01

    Much research has been devoted to measurement of total blood volume (TBV) and cardiac output (CO) in humans but not enough effort has been devoted to collection and reduction of results for the purpose of deriving typical or {open_quotes}reference{close_quotes} values. Identification of normal values for TBV and CO is needed not only for clinical evaluations but also for the development of biokinetic models for ultra-short-lived radionuclides used in nuclear medicine (Leggett and Williams 1989). The purpose of this report is to offer reference values for TBV and CO, along with estimates of the associated uncertainties that arise from intra- and inter-subject variation, errors in measurement techniques, and other sources. Reference values are derived for basal supine CO and TBV in reference adult humans, and differences associated with age, sex, body size, body position, exercise, and other circumstances are discussed.

  3. Pulmonary Artery Catheter (PAC) Accuracy and Efficacy Compared with Flow Probe and Transcutaneous Doppler (USCOM): An Ovine Cardiac Output Validation.

    PubMed

    Phillips, Robert A; Hood, Sally G; Jacobson, Beverley M; West, Malcolm J; Wan, Li; May, Clive N

    2012-01-01

    Background. The pulmonary artery catheter (PAC) is an accepted clinical method of measuring cardiac output (CO) despite no prior validation. The ultrasonic cardiac output monitor (USCOM) is a noninvasive alternative to PAC using Doppler ultrasound (CW). We compared PAC and USCOM CO measurements against a gold standard, the aortic flow probe (FP), in sheep at varying outputs. Methods. Ten conscious sheep, with implanted FPs, had measurements of CO by FP, USCOM, and PAC, at rest and during intervention with inotropes and vasopressors. Results. CO measurements by FP, PAC, and USCOM were 4.0 ± 1.2 L/min, 4.8 ± 1.5 L/min, and 4.0 ± 1.4 L/min, respectively, (n = 280, range 1.9 L/min to 11.7 L/min). Percentage bias and precision between FP and PAC, and FP and USCOM was -17 and 47%, and 1 and 36%, respectively. PAC under-measured Dobutamine-induced CO changes by 20% (relative 66%) compared with FP, while USCOM measures varied from FP by 3% (relative 10%). PAC reliably detected -30% but not +40% CO changes, as measured by receiver operating characteristic area under the curve (AUC), while USCOM reliably detected ±5% changes in CO (AUC > 0.70). Conclusions. PAC demonstrated poor accuracy and sensitivity as a measure of CO. USCOM provided equivalent measurements to FP across a sixfold range of outputs, reliably detecting ±5% changes.

  4. The transcutaneous oxygen challenge test: a noninvasive method for detecting low cardiac output in septic patients.

    PubMed

    He, Huai-Wu; Liu, Da-Wei; Long, Yun; Wang, Xiao-Ting; Chai, Wen-Zhao; Zhou, Xiang

    2012-02-01

    The transcutaneous partial pressure of oxygen (PtcO₂) index has been used to detect low-flow state in circulatory failure, but the value of the transcutaneous oxygen challenge test (OCT) to estimate low cardiac output has not been thoroughly evaluated. The prospective observational study examined 62 septic patients requiring PiCCO-Plus for cardiac output monitoring. Simultaneous basal blood gases from the arterial, central venous catheters were obtained. Cardiac indices were measured by the transpulmonary thermodilution technique at the same time, then the 10-min inspired 1.0 fractional inspired oxygen concentration (FIO₂) defined as the OCT was performed. Transcutaneous partial pressure of oxygen was measured continuously by using a noninvasive transcutaneous monitor throughout the test. The values for arterial pressure of oxygen (PaO₂) were examined on inspired of 1.0 FIO₂. We calculated the PtcO₂ index = (baseline PtcO₂/baseline PaO₂), 10-min OCT (10 OCT) = (PtcO₂ after 10 min on inspired 1.0 O₂) - (baseline PtcO₂), and the oxygen challenge index = (10 OCT) / (PaO₂ on inspired 1.0 O₂ - baseline PaO₂). Patients were divided into two groups: a normal cardiac index (CI) group with CI of greater than 3 L/min per m (n = 41) and a low CI group with CI of 3 L/min per m or less (n = 21). The 10 OCT and the oxygen challenge index predicted a low CI (≤ 3 L/min per m) with an accuracy that was similar to central venous oxygen saturation, which was significantly better than the PtcO₂ index. For a 10 OCT value of 53 mmHg, sensitivity was 0.83; specificity, 0.86; a positive predictive value, 0.92; and a negative predictive value, 0.72 for detecting CI of 3 L/min per m or less. We propose that the OCT substituted for the PtcO₂ index as an accurate alternative method of PtcO₂ for revealing low CI in septic patients.

  5. Is pulmonary gas exchange during exercise in hypoxia impaired with the increase of cardiac output?

    PubMed

    Calbet, José A L; Robach, Paul; Lundby, Carsten; Boushel, Robert

    2008-06-01

    During exercise in humans, the alveolar-arterial O(2) tension difference ((A-a)DO(2)) increases with exercise intensity and is an important factor determining the absolute level of oxygen binding to hemoglobin and therefore the level of systemic oxygen transport. During exercise in hypoxia, the (A-a)DO(2) is accentuated. Using the multiple inert gas elimination technique it has been shown that during exercise in acute hypoxia the contribution of ventilation-perfusion inequality to (A-a)DO(2) is rather small and in the absence of pulmonary edema intrapulmonary shunts can be ruled out. This implies that the main mechanism limiting pulmonary gas exchange is diffusion limitation. It is presumed that an elevation of cardiac output during exercise in acute hypoxia should increase the (A-a)DO(2). However, no studies have examined how variations in cardiac output independently affect pulmonary diffusion with increases in exercise intensity. We have consistently observed that during steady-state, submaximal (100-120 W) exercise on the cycle ergometer in hypoxia the lung can accommodate an increase in cardiac output of approximately 2 L x min(-1) without any significant effect on pulmonary gas exchange. This result contrasts with the predicted effect of cardiac output on (A-a)DO(2) using the model of Piiper and Scheid, and thus indicates that an elevation of cardiac output is not necessarily accompanied by a reduction of mean transit time and (or) diffusion limitation during submaximal exercise in acute hypoxia. It remains to be determined what is the influence of changes in cardiac output per se on pulmonary gas exchange during high-intensity exercise.

  6. Rowing increases stroke volume and cardiac output to a greater extent than cycling.

    PubMed

    Horn, P; Ostadal, P; Ostadal, B

    2015-01-01

    Exercise stimulates increases in heart rate (HR), stroke volume (SV) and cardiac output (CO). These adaptive mechanisms are strongly dependent on the type of exercise. Both rowing and cycling are widely used for physical training worldwide; however, evidence regarding the differences in major hemodynamic parameters during rowing and cycling remains insufficient. Ten healthy male volunteers were randomly assigned to perform either a rowing or cycling exercise. After 20 min rest, the group who had rowed first performed the cycling exercise and vice versa. Exercise was performed at a power-to-weight ratio of 2 W/kg for 2 min. HR, SV, CO and blood pressure (BP) were measured noninvasively using pulse-wave analysis at baseline and immediately after each exercise. HR, SV and CO were significantly higher after exercise than at rest. Whereas HR was comparable between rowing and cycling, SV and CO were significantly higher after rowing than after cycling. BP was comparable among all three measurements. Rowing increased SV and CO to a greater extent than cycling, whereas HR and BP were not influenced by the type of exercise. Our data suggest that rowing leads to more extensive stimulation of cardiac contractility and/or decreases in peripheral vascular resistance compared with cycling.

  7. Non-invasive assessment of cardiac output during mechanical ventilation - a novel approach using an inert gas rebreathing method.

    PubMed

    Nickl, Werner; Bugaj, Till; Mondritzki, Thomas; Kuhlebrock, Kathrin; Dinh, Winfried; Krahn, Thomas; Sohler, Florian; Truebel, Hubert

    2011-06-01

    Measurement of cardiac output (CO) is of importance in the diagnostic of critically ill patients. The invasive approach of thermodilution (TD) via pulmonary artery catheter is clinically widely used. A new non-invasive technique of inert gas rebreathing (IGR) shows a good correlation with TD measurements in spontaneously breathing individuals. For the first time, we investigated whether IGR can also be applied to sedated and mechanically ventilated subjects with a clinical point of care device. CO data from IGR were compared with TD in six healthy mongrel dogs. Data sampling was repeated under baseline conditions (rest) and under stress challenge by applying 10 μg/kg/min of dobutamine intravenously. Switching from mechanical ventilation to IGR, as well as the rebreathing procedures, were carried out manually. Cardiac output data from IGR and TD correlated with a coefficient of r=0.90 (95% confidence interval [0.81; 0.95]). The Bland-Altman analysis showed a bias of 0.46 l/min for the IGR CO measurements. Ninety-five percent of all differences fall in the interval [-1.03; 1.95], being the limit of the ± 1.96 standard deviation lines. IGR is a new approach for non-invasive cardiac output measurement in mechanically ventilated individuals, but requires further investigation for clinical use.

  8. A multiple-input multiple-output system for modeling the cardiac dynamics.

    PubMed

    Monzon, Jorge E; Picaza, Carlos Alvarez; Pisarello, Maria I

    2011-01-01

    We describe the dynamics of the cardiovascular system by finding the input-output relationships in the state space of a functional cardiac model, based on state equations and observability criteria of control theory. The unit step response of the multiple-input multiple-output system model illustrates the damping effect of the arterial wall to the pulsatility of the heart. Our results show that hypertensive patients exhibit a lower inertia of the blood flow.

  9. Laboratory measurement of human power output during maximum intensity exercise

    NASA Astrophysics Data System (ADS)

    Lakomy, Henryk K. A.

    1993-11-01

    The power output of an athlete decreases rapidly with time. The author describes different ways of measuring power output, including a unique method developed at Loughborough University for measuring the power developed by a sprint runner.

  10. In vivo validation of cardiac output assessment in non-standard 3D echocardiographic images

    NASA Astrophysics Data System (ADS)

    Nillesen, M. M.; Lopata, R. G. P.; de Boode, W. P.; Gerrits, I. H.; Huisman, H. J.; Thijssen, J. M.; Kapusta, L.; de Korte, C. L.

    2009-04-01

    Automatic segmentation of the endocardial surface in three-dimensional (3D) echocardiographic images is an important tool to assess left ventricular (LV) geometry and cardiac output (CO). The presence of speckle noise as well as the nonisotropic characteristics of the myocardium impose strong demands on the segmentation algorithm. In the analysis of normal heart geometries of standardized (apical) views, it is advantageous to incorporate a priori knowledge about the shape and appearance of the heart. In contrast, when analyzing abnormal heart geometries, for example in children with congenital malformations, this a priori knowledge about the shape and anatomy of the LV might induce erroneous segmentation results. This study describes a fully automated segmentation method for the analysis of non-standard echocardiographic images, without making strong assumptions on the shape and appearance of the heart. The method was validated in vivo in a piglet model. Real-time 3D echocardiographic image sequences of five piglets were acquired in radiofrequency (rf) format. These ECG-gated full volume images were acquired intra-operatively in a non-standard view. Cardiac blood flow was measured simultaneously by an ultrasound transit time flow probe positioned around the common pulmonary artery. Three-dimensional adaptive filtering using the characteristics of speckle was performed on the demodulated rf data to reduce the influence of speckle noise and to optimize the distinction between blood and myocardium. A gradient-based 3D deformable simplex mesh was then used to segment the endocardial surface. A gradient and a speed force were included as external forces of the model. To balance data fitting and mesh regularity, one fixed set of weighting parameters of internal, gradient and speed forces was used for all data sets. End-diastolic and end-systolic volumes were computed from the segmented endocardial surface. The cardiac output derived from this automatic segmentation was

  11. Age and sex influence the balance between maximal cardiac output and peripheral vascular reserve.

    PubMed

    Ridout, Samuel J; Parker, Beth A; Smithmyer, Sandra L; Gonzales, Joaquin U; Beck, Kenneth C; Proctor, David N

    2010-03-01

    We evaluated the influence of age and sex on the relationship between central and peripheral vasodilatory capacity. Healthy men (19 younger, 12 older) and women (17 younger, 17 older) performed treadmill and knee extensor exercise to fatigue on separate days while maximal cardiac output (Q, acetylene uptake) and peak femoral blood flow (FBF, Doppler ultrasound) were measured, respectively. Maximal Q was reduced with age similarly in men (Y: 23.6 +/- 2.7 vs. O: 17.4 +/- 3.5 l/min; P < 0.05) and women (Y: 17.7 +/- 1.9 vs. O: 12.3 +/- 1.6 l/min; P < 0.05). Peak FBF was similar between younger (Y) and older (O) men (Y: 2.1 +/- 0.5 vs. O: 2.2 +/- 0.7 l/min) but was lower in older women compared with younger women (Y: 1.9 +/- 0.4 vs. O: 1.4 +/- 0.4 l/min; P < 0.05). Maximal Q was positively correlated with peak FBF in men (Y: r = 0.55, O: r = 0.74; P < 0.05) but not in women (Y: r = 0.34, O: r = 0.10). Normalization of cardiac output to appendicular muscle mass and peak FBF to quadriceps mass reduced the correlation between these variables in younger men (r = 0.30), but the significant association remained in older men (r = 0.68; P < 0.05), with no change in women. These data suggest that 1) aerobic capacity is associated with peripheral vascular reserve in men but not women, and 2) aging is accompanied by a more pronounced sex difference in this relationship.

  12. Capnodynamic assessment of effective lung volume during cardiac output manipulations in a porcine model.

    PubMed

    Hällsjö Sander, Caroline; Lönnqvist, Per-Arne; Hallbäck, Magnus; Sipmann, Fernando Suarez; Wallin, Mats; Oldner, Anders; Björne, Håkan

    2016-12-01

    A capnodynamic calculation of effective pulmonary blood flow includes a lung volume factor (ELV) that has to be estimated to solve the mathematical equation. In previous studies ELV correlated to reference methods for functional residual capacity (FRC). The aim was to evaluate the stability of ELV during significant manipulations of cardiac output (CO) and assess the agreement for absolute values and trending capacity during PEEP changes at different lung conditions. Ten pigs were included. Alterations of alveolar carbon dioxide were induced by cyclic reoccurring inspiratory holds. The Sulphur hexafluoride technique for FRC measurements was used as reference. Cardiac output was altered by preload reduction and inotropic stimulation at PEEP 5 and 12 cmH2O both in normal lung conditions and after repeated lung lavages. ELV at baseline PEEP 5 was [mean (SD)], 810 (163) mL and decreased to 400 (42) mL after lavage. ELV was not significantly affected by CO alterations within the same PEEP level. In relation to FRC the overall bias (limits of agreement) was -35 (-271 to 201) mL, and percentage error 36 %. A small difference between ELV and FRC was seen at PEEP 5 cmH2O before lavage and at PEEP 12 cmH2O after lavage. ELV trending capability between PEEP steps, showed a concordance rate of 100 %. ELV was closely related to FRC and remained stable during significant changes in CO. The trending capability was excellent both before and after surfactant depletion.

  13. A comparison of cardiac output by thoracic impedance and direct fick in children with congenital heart disease undergoing diagnostic cardiac catheterization.

    PubMed

    Taylor, Katherine; La Rotta, Gustavo; McCrindle, Brian W; Manlhiot, Cedric; Redington, Andrew; Holtby, Helen

    2011-10-01

    To evaluate the measurement of cardiac output (CO) using continuous electrical bioimpedance cardiography (Physioflow; Neumedx, Philadelphia, PA) (CO(PF)) with a simultaneous direct Fick measurement (CO(FICK)) in children with congenital heart disease. A prospective cohort study comparing 2 methods of measurement of CO. A quaternary university-affiliated pediatric hospital. Children undergoing cardiac catheterization for clinical care. The Physioflow measured continuous real time CO in 15-second epochs and simultaneous measurement of cardiac output by direct Fick (with mass spectrometry to assess VO(2)) were acquired. Sixty-five patients were recruited, and data from 56 (25 males) were adequate for analysis. The median age at study was 3.5 years (range, 0.4-16.6 years), and the median body surface area was 0.62 m(2) (range, 0.31-1.71). There were 25 of 56 (45%) with univentricular physiology. A total of 19,228 Physioflow data points were available for the analysis of which 14,569 (76%) were valid; 96% of the invalid measurements were identified as artifacts by the device. The average cardiac index of valid measurements was 3.09 ± 0.72 L/min/m(2). Compared with the Fick CO, the mean bias was -0.09 L/min, but the 95% limits of agreement were -3.20 to +3.01 L/min/m(2). Consequently, only 20 of 56 (36%) of measurements were within 20%, and 31 of 56 (55%) of measurements were within 30% of each other. Compared with measurements made by direct Fick, CO measured using the Physioflow device was unreliable in anesthetized children with congenital heart disease. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Pilot Study: Estimation of Stroke Volume and Cardiac Output from Pulse Wave Velocity.

    PubMed

    Obata, Yurie; Mizogami, Maki; Nyhan, Daniel; Berkowitz, Dan E; Steppan, Jochen; Barodka, Viachaslau

    2017-01-01

    Transesophageal echocardiography (TEE) is increasingly replacing thermodilution pulmonary artery catheters to assess hemodynamics in patients at high risk for cardiovascular morbidity. However, one of the drawbacks of TEE compared to pulmonary artery catheters is the inability to measure real time stroke volume (SV) and cardiac output (CO) continuously. The aim of the present proof of concept study was to validate a novel method of SV estimation, based on pulse wave velocity (PWV) in patients undergoing cardiac surgery. This is a retrospective observational study. We measured pulse transit time by superimposing the radial arterial waveform onto the continuous wave Doppler waveform of the left ventricular outflow tract, and calculated SV (SVPWV) using the transformed Bramwell-Hill equation. The SV measured by TEE (SVTEE) was used as a reference. A total of 190 paired SV were measured from 28 patients. A strong correlation was observed between SVPWV and SVTEE with the coefficient of determination (R2) of 0.71. A mean difference between the two (bias) was 3.70 ml with the limits of agreement ranging from -20.33 to 27.73 ml and a percentage error of 27.4% based on a Bland-Altman analysis. The concordance rate of two methods was 85.0% based on a four-quadrant plot. The angular concordance rate was 85.9% with radial limits of agreement (the radial sector that contained 95% of the data points) of ± 41.5 degrees based on a polar plot. PWV based SV estimation yields reasonable agreement with SV measured by TEE. Further studies are required to assess its utility in different clinical situations.

  15. Pilot Study: Estimation of Stroke Volume and Cardiac Output from Pulse Wave Velocity

    PubMed Central

    Nyhan, Daniel; Berkowitz, Dan E.; Steppan, Jochen; Barodka, Viachaslau

    2017-01-01

    Background Transesophageal echocardiography (TEE) is increasingly replacing thermodilution pulmonary artery catheters to assess hemodynamics in patients at high risk for cardiovascular morbidity. However, one of the drawbacks of TEE compared to pulmonary artery catheters is the inability to measure real time stroke volume (SV) and cardiac output (CO) continuously. The aim of the present proof of concept study was to validate a novel method of SV estimation, based on pulse wave velocity (PWV) in patients undergoing cardiac surgery. Methods This is a retrospective observational study. We measured pulse transit time by superimposing the radial arterial waveform onto the continuous wave Doppler waveform of the left ventricular outflow tract, and calculated SV (SVPWV) using the transformed Bramwell-Hill equation. The SV measured by TEE (SVTEE) was used as a reference. Results A total of 190 paired SV were measured from 28 patients. A strong correlation was observed between SVPWV and SVTEE with the coefficient of determination (R2) of 0.71. A mean difference between the two (bias) was 3.70 ml with the limits of agreement ranging from -20.33 to 27.73 ml and a percentage error of 27.4% based on a Bland-Altman analysis. The concordance rate of two methods was 85.0% based on a four-quadrant plot. The angular concordance rate was 85.9% with radial limits of agreement (the radial sector that contained 95% of the data points) of ± 41.5 degrees based on a polar plot. Conclusions PWV based SV estimation yields reasonable agreement with SV measured by TEE. Further studies are required to assess its utility in different clinical situations. PMID:28060961

  16. Effect of Hemorrhage on Cardiac Output, PVP, Alodosterone and Diuresis during Immersion in Men

    NASA Technical Reports Server (NTRS)

    Simanonok, K.; Greenleaf, John E.; Bernauer, E. M.; Wade, C. E.; Keil, L. C.

    1990-01-01

    The purpose of this study was to test the hypothesis that a reduction in blood volume would attenuate or eliminate immersion-induced increases in cardiac output (Q (sup dot) sub co)) and urine excretion, and to investigate accompanying vasoactive and fluid-electrolyte hormonal responses.

  17. The pioneering use of systems analysis to study cardiac output regulation.

    PubMed

    Hall, John E

    2004-11-01

    This essay examines the historical significance of an APS classic paper that is freely available online: Guyton AC, Lindsey AW, and Kaufmann BN. Effect of mean circulatory filling pressure and other peripheral circulatory factors on cardiac output. Am J Physiol 180: 463-468, 1955 (http://ajplegacy.physiology.org/cgi/reprint/180/3/463). Copyright 2004 American Physiological Society

  18. Monitoring Non-Invasive Cardiac Output and Stroke Volume during Experimental Human Hypovolaemia and Resuscitation

    DTIC Science & Technology

    2011-01-01

    FloTrac method (Edwards Lifesciences , Irvine, CA, USA) ‘is the physiological premise that PP is pro- portional to stroke volume’,9 whereas the PulseCO...cardiac output and stroke volume BJA 29 9 Edwards Lifesciences . Available from http://www.edwards.com/ sitecollectionimages/products/mininvasive

  19. Single-breath breath-holding estimate of pulmonary blood flow in man: comparison with direct Fick cardiac output.

    PubMed

    Kendrick, A H; Rozkovec, A; Papouchado, M; West, J; Laszlo, G

    1989-06-01

    1. Resting pulmonary blood flow (Q), using the uptake of the soluble inert gas Freon-22 and an indirect estimate of lung tissue volume, has been estimated during breath-holding (Qc) and compared with direct Fick cardiac output (Qf) in 16 patients with various cardiac disorders. 2. The effect of breath-hold time was investigated by comparing Qc estimated using 6 and 10 s of breath-holding in 17 patients. Repeatability was assessed by duplicate measurements of Qc in the patients and in six normal subjects. 3. Qc tended to overestimate Qf, the bias and error being 0.09 l/min and 0.59, respectively. The coefficient of repeatability for Qc in the patients was 0.75 l/min and in the normal subjects was 0.66 l/min. For Qf it was 0.72 l/min. There was no significant difference in Qc measured at the two breath-hold times. 4. The technique is simple to perform, and provides a rapid estimate of Q, monitoring acute and chronic changes in cardiac output in normal subjects and patients with cardiac disease.

  20. Comparison of estimates of cardiac output by indicator dilution and freon 22 uptake during gas mixing in dogs.

    PubMed

    Jones, H A; Lakshminarayan, S; Becket, J M; Hughes, J M

    1991-06-01

    The aim was to measure cardiac output while rebreathing tidal volumes, by correction of soluble gas uptake for gaseous mixing. Simultaneous measurements of cardiac output by indocyanin green and freon 22 uptake during rebreathing were made. Mixing for a hypothetical gas of identical gaseous diffusivity to freon 22 was calculated by interpolation between concentrations of two insoluble gases, helium and sulphur hexafluoride. Mixing efficiency was estimated by the number of breaths for helium to become 99% equilibrated with lung gas (n99-He). Five anaesthetised dogs rebreathed at intervals with 300 ml of test gas. 63 comparisons of cardiac output using indocyanin green and freon 22 uptake (over breaths 7-13 using the mean mixed volume of distribution), gave a mean (95% confidence interval) underestimation of 0.345 (0.093-0.597) litre.min-1 (14%). Exclusion of 12 points in which n99-He was greater than 15 resulted in a mean underestimation of 0.052(-0.163-0.267) litre.min-1 (2%). Without correction for gaseous mixing, freon 22 uptake for these data overestimated blood flow by a mean of 1.31 litre.min-1 (overestimation = 2.7 over breaths 5-11). Use of the equilibrium volume of distribution resulted in an overestimation of blood flow relative to green dye of 1.2 litre.min-1 (breaths 5-11) and 0.76 litre.min-1 (breaths 7-13). Estimates of cardiac output by soluble gas uptake are optimal when correction is made for mixing of gas of identical diffusivity. The mean mixed gas volume gives the best correlation with the reference method, implying a selective distribution of blood flow to the better ventilated areas.

  1. Pulmonary diffusing capacity, capillary blood volume, and cardiac output during sustained microgravity

    NASA Technical Reports Server (NTRS)

    Prisk, G. K.; Guy, Harold J. B.; Elliott, Ann R.; Deutschman, Robert A., III; West, John B.

    1993-01-01

    We measured pulmonary diffusing capacity (DL), diffusing capacity per unit lung volume, pulmonary capillary blood volume (Vc), membrane diffusing capacity (Dm), pulmonary capillary blood flow or cardiac output (Qc), and cardiac stroke volume (SV) in four subjects exposed to nine days of microgravity. DL in microgravity was elevated compared with preflight standing values and was higher than preflight supine because of the elevation of both Vc and Dm. The elevation in Vc was comparable to that measured supine in 1 G, but the increase in Dm was in sharp contrast to the supine value. We postulate that, in 0 G, pulmonary capillary blood is evenly distributed throughout the lung, providing for uniform capillary filling, leading to an increase in the surface area available for diffusion. By contrast, in the supine 1-G state, the capillaries are less evenly filled, and although a similar increase in blood volume is observed, the corresponding increase in surface area does not occur. DL and its subdivisions showed no adaptive changes from the first measurement 24 h after the start of 0 G to eight days later. Similarly, there were no trends in the postflight data, suggesting that the principal mechanism of these changes was gravitational. The increase in Dm suggests that subclinical pulmonary edema did not result from exposure to 0 G. Qc was modestly increased inflight and decreased postflight compared with preflight standing. Compared with preflight standing, SV was increased 46 percent inflight and decreased 14 percent in the 1st week postflight. There were temporal changes in Qc and SV during 0 G, with the highest values recorded at the first measurement, 24 h into the flight. The lowest values of Qc and SV occurred on the day of return.

  2. Contribution of lung stretch depressor reflex to nonlinear fall in cardiac output during PEEP.

    PubMed

    Schreuder, J J; Jansen, J R; Versprille, A

    1984-06-01

    The hypothesis that lung stretch reflexes elicit negative cardiovascular effects during positive end-expiratory pressure (PEEP) application in a ramp procedure up to 15 cmH2O was tested in piglets under steady-state anesthesia and muscle relaxation. The effects of lung stretch on hemodynamics were studied by comparing the differences in responses during PEEP application with two different tidal volumes. In both ventilatory conditions cardiac output and aortic pressure decreased nonlinearly in three phases with the rise of PEEP: a gradual decrease in phase I, a sharp decrease in phase II, and again a more gradual decrease in phase III. Heart rate decreased significantly in phase II. In the series with the larger tidal volume, implying more lung stretch during insufflation, phase II was between a PEEP of 2.6 and 9 cmH2O. In the series with the smaller tidal volume, phase II occurred between 5.7 and 10.5 cmH2O. To assess the contribution of lung stretch reflexes to the decrease in cardiac output we also related cardiac output to the changes in central venous pressure. Again a nonlinear response was observed, indicating that an additional effect besides the rise in mean central venous pressure was involved in the decrease in cardiac output. During ventilation with the smaller tidal volume, phase II of the decrease in cardiac output was also shifted to higher values of mean central venous pressure, which only could be ascribed to the differences in lung stretch at insufflation. It appeared that under circumstances of artificial ventilation the onset of the reflex is determined by a characteristic threshold of lung stretch.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Asymmetric sympathetic output: The dorsomedial hypothalamus as a potential link between emotional stress and cardiac arrhythmias.

    PubMed

    Fontes, Marco Antônio Peliky; Filho, Marcelo Limborço; Santos Machado, Natália L; de Paula, Cristiane Amorim; Souza Cordeiro, Letícia M; Xavier, Carlos Henrique; Marins, Fernanda Ribeiro; Henderson, Luke; Macefield, Vaughan G

    2017-01-17

    The autonomic response to emotional stress, while involving several target organs, includes an important increase in sympathetic drive to the heart. There is ample evidence that cardiac sympathetic innervation is lateralized, and asymmetric autonomic output to the heart during stress is postulated to be a causal factor that precipitates cardiac arrhythmias. Recent animal studies provided a new picture of the central pathways involved in the cardiac sympathetic response evoked by emotional stress, pointing out a key role for the region of dorsomedial hypothalamus. However, how much of this information can be extrapolated to humans? Analysis of human functional imaging data at rest or during emotional stress shows some consistency with the components that integrate these pathways, and attention must be given to the asymmetric activation of subcortical sites. In this short review, we will discuss related findings in humans and animals, aiming to understand the neurogenic background for the origin of emotional stress-induced cardiac arrhythmias.

  4. Accuracy of Cardiac Output by Nine Different Pulse Contour Algorithms in Cardiac Surgery Patients: A Comparison with Transpulmonary Thermodilution.

    PubMed

    Broch, Ole; Bein, Berthold; Gruenewald, Matthias; Masing, Sarah; Huenges, Katharina; Haneya, Assad; Steinfath, Markus; Renner, Jochen

    2016-01-01

    Objective. Today, there exist several different pulse contour algorithms for calculation of cardiac output (CO). The aim of the present study was to compare the accuracy of nine different pulse contour algorithms with transpulmonary thermodilution before and after cardiopulmonary bypass (CPB). Methods. Thirty patients scheduled for elective coronary surgery were studied before and after CPB. A passive leg raising maneuver was also performed. Measurements included CO obtained by transpulmonary thermodilution (COTPTD) and by nine pulse contour algorithms (COX1-9). Calibration of pulse contour algorithms was performed by esophageal Doppler ultrasound after induction of anesthesia and 15 min after CPB. Correlations, Bland-Altman analysis, four-quadrant, and polar analysis were also calculated. Results. There was only a poor correlation between COTPTD and COX1-9 during passive leg raising and in the period before and after CPB. Percentage error exceeded the required 30% limit. Four-quadrant and polar analysis revealed poor trending ability for most algorithms before and after CPB. The Liljestrand-Zander algorithm revealed the best reliability. Conclusions. Estimation of CO by nine different pulse contour algorithms revealed poor accuracy compared with transpulmonary thermodilution. Furthermore, the less-invasive algorithms showed an insufficient capability for trending hemodynamic changes before and after CPB. The Liljestrand-Zander algorithm demonstrated the highest reliability. This trial is registered with NCT02438228 (ClinicalTrials.gov).

  5. Accuracy of Cardiac Output by Nine Different Pulse Contour Algorithms in Cardiac Surgery Patients: A Comparison with Transpulmonary Thermodilution

    PubMed Central

    Bein, Berthold; Gruenewald, Matthias; Masing, Sarah; Huenges, Katharina; Haneya, Assad; Steinfath, Markus; Renner, Jochen

    2016-01-01

    Objective. Today, there exist several different pulse contour algorithms for calculation of cardiac output (CO). The aim of the present study was to compare the accuracy of nine different pulse contour algorithms with transpulmonary thermodilution before and after cardiopulmonary bypass (CPB). Methods. Thirty patients scheduled for elective coronary surgery were studied before and after CPB. A passive leg raising maneuver was also performed. Measurements included CO obtained by transpulmonary thermodilution (COTPTD) and by nine pulse contour algorithms (COX1–9). Calibration of pulse contour algorithms was performed by esophageal Doppler ultrasound after induction of anesthesia and 15 min after CPB. Correlations, Bland-Altman analysis, four-quadrant, and polar analysis were also calculated. Results. There was only a poor correlation between COTPTD and COX1–9 during passive leg raising and in the period before and after CPB. Percentage error exceeded the required 30% limit. Four-quadrant and polar analysis revealed poor trending ability for most algorithms before and after CPB. The Liljestrand-Zander algorithm revealed the best reliability. Conclusions. Estimation of CO by nine different pulse contour algorithms revealed poor accuracy compared with transpulmonary thermodilution. Furthermore, the less-invasive algorithms showed an insufficient capability for trending hemodynamic changes before and after CPB. The Liljestrand-Zander algorithm demonstrated the highest reliability. This trial is registered with NCT02438228 (ClinicalTrials.gov). PMID:28116294

  6. Changes in cardiac output during air ambulance repatriation.

    PubMed

    Malagon, I; Grounds, R M; Bennett, E D

    1996-12-01

    To measure, with the use of suprasternal Doppler ultrasound, the hemodynamic changes in patients and volunteers during air ambulance repatriation. Unblinded prospective observational study. Chartered air ambulances for the international repatriation of patients. Six medical crew members and seven patients transported back to hospitals in the UK. The measurement of non-invasive blood pressure, ECG, heart rate, oxygen saturation and hemodynamic variables with suprasternal Doppler. There was a drop in systolic and mean arterial blood pressure in the patient's group once in the air. Oxygen saturation dropped in both groups once at cruising altitude. Heart rate remained unchanged. Stroke distance and minute distance increased significantly in the patient's group and non-significantly in the volunteers. Peak velocity increased significantly in the patient's group. There was an overall reduction of systemic vascular resistance during take off and once at cruising altitude. Hemodynamic changes happen during air ambulance transportation in fit and healthy volunteers and patients alike. These may be due to a combination of hypobaric hypoxia and gravitational forces. It is necessary to establish if these changes have short- or long-term effects in the critically ill.

  7. A comparison of the Nexfin® and transcardiopulmonary thermodilution to estimate cardiac output during coronary artery surgery.

    PubMed

    Broch, O; Renner, J; Gruenewald, M; Meybohm, P; Schöttler, J; Caliebe, A; Steinfath, M; Malbrain, M; Bein, B

    2012-04-01

    The newly introduced Nexfin(®) device allows analysis of the blood pressure trace produced by a non-invasive finger cuff. We compared the cardiac output derived from the Nexfin and PiCCO, using transcardiopulmonary thermodilution, during cardiac surgery. Forty patients with preserved left ventricular function undergoing elective coronary artery bypass graft surgery were studied after induction of general anaesthesia and until discharge to the intensive care unit. There was a significant correlation between Nexfin and PiCCO before (r(2) = 0.81, p < 0.001) and after (r(2) = 0.56, p < 0.001) cardiopulmonary bypass. Bland-Altman analysis demonstrated the mean bias of Nexfin to be -0.1 (95% limits of agreement -0.6 to +0.5, percentage error 23%) and -0.1 (-0.8 to +0.6, 26%) l.min(-1).m(-2), before and after cardiopulmonary bypass, respectively. After a passive leg-raise was performed, there was also good correlation between the two methods, both before (r(2) = 0.72, p < 0.001) and after (r(2) = 0.76, p < 0.001) cardiopulmonary bypass. We conclude that the Nexfin is a reliable method of measuring cardiac output during and after cardiac surgery.

  8. Assessment of the effect of vasodilators on the distribution of cardiac output by whole-body Thallium imaging

    SciTech Connect

    Juni, J.E.; Wallis, J.; Diltz, E.; Nicholas, J.; Lahti, D.; Pitt, B.

    1985-05-01

    Vasodilator therapy (tx) of congestive heart failure (CHF) has been shown to be effective in increasing cardiac output (CO) and lowering vascular resistance. Unfortunately, these hemodynamic effects are not usually accompanied by improved peripheral circulation of exercise capacity. To assess the effect of a new vasodilator, Cl-914, on the redistribution of CO to the peripheral circulation, the authors performed testing whole-body thallium scanning (WB-Th) on 6 patients (pts) with severe CHF. Immediately following i.v. injection of 1.5 mCi Th-201, WB scanning was performed from anterior and posterior views. Regions of interest were defined for the peripheral (P) muscles (legs and arms), central torso (C), and splanchnic bed (S). The geometric mean of activity in these regions was calculated from both views. Each pt was studied before tx and again, after 1 week on tx. Invasive measurements revealed that all pts had significant improvements in resting cardiac output (mean increase 49%) and vascular resistance (mean decrease 30%). Unlike other vasodilators, all CI-914 pts had a significant improvement in treadmill exercise capacity (mean increase 54%). WB-Th revealed a significant shift in CO to the peripheral circulation with P:C increased 33.2% (rho= .001) and P:S increased 29% (rho=.01). Vasoactive drugs may significantly alter the relative distribution of cardiac output. WB-Th scanning provides a simple quantitative means of following such changes.

  9. Pulmonary Artery Catheter (PAC) Accuracy and Efficacy Compared with Flow Probe and Transcutaneous Doppler (USCOM): An Ovine Cardiac Output Validation

    PubMed Central

    Phillips, Robert A.; Hood, Sally G.; Jacobson, Beverley M.; West, Malcolm J.; Wan, Li; May, Clive N.

    2012-01-01

    Background. The pulmonary artery catheter (PAC) is an accepted clinical method of measuring cardiac output (CO) despite no prior validation. The ultrasonic cardiac output monitor (USCOM) is a noninvasive alternative to PAC using Doppler ultrasound (CW). We compared PAC and USCOM CO measurements against a gold standard, the aortic flow probe (FP), in sheep at varying outputs. Methods. Ten conscious sheep, with implanted FPs, had measurements of CO by FP, USCOM, and PAC, at rest and during intervention with inotropes and vasopressors. Results. CO measurements by FP, PAC, and USCOM were 4.0 ± 1.2 L/min, 4.8 ± 1.5 L/min, and 4.0 ± 1.4 L/min, respectively, (n = 280, range 1.9 L/min to 11.7 L/min). Percentage bias and precision between FP and PAC, and FP and USCOM was −17 and 47%, and 1 and 36%, respectively. PAC under-measured Dobutamine-induced CO changes by 20% (relative 66%) compared with FP, while USCOM measures varied from FP by 3% (relative 10%). PAC reliably detected −30% but not +40% CO changes, as measured by receiver operating characteristic area under the curve (AUC), while USCOM reliably detected ±5% changes in CO (AUC > 0.70). Conclusions. PAC demonstrated poor accuracy and sensitivity as a measure of CO. USCOM provided equivalent measurements to FP across a sixfold range of outputs, reliably detecting ±5% changes. PMID:22649718

  10. Clinical usefulness of the definitions for defining characteristics of activity intolerance, excess fluid volume and decreased cardiac output in decompensated heart failure: a descriptive exploratory study.

    PubMed

    de Souza, Vanessa; Zeitoun, Sandra Salloum; Lopes, Camila Takao; de Oliveira, Ana Paula Dias; Lopes, Juliana de Lima; de Barros, Alba Lucia Bottura Leite

    2015-09-01

    To assess the clinical usefulness of the operational definitions for the defining characteristics of the NANDA International nursing diagnoses, activity intolerance, decreased cardiac output and excess fluid volume, and the concomitant presence of those diagnoses in patients with decompensated heart failure. Content validity of the operational definitions for the defining characteristics of activity intolerance, excess fluid volume and decreased cardiac output have been previously validated by experts. Their clinical usefulness requires clinical validation. This was a descriptive exploratory study. Two expert nurses independently assessed 25 patients with decompensated heart failure for the presence or absence of 29 defining characteristics. Interrater reliability was analysed using the Kappa coefficient as a measure of clinical usefulness. The Fisher's exact test was used to test the association of the defining characteristics of activity intolerance and excess fluid volume in the presence of decreased cardiac output, and the correlation between the three diagnoses. Assessments regarding the presence of all defining characteristics reached 100% agreement, except with anxiety. Five defining characteristics of excess fluid volume were significantly associated with the presence of decreased cardiac output. Concomitant presence of the three diagnoses occurred in 80% of the patients. However, there was no significant correlation between the three diagnoses. The operational definitions for the diagnoses had strong interrater reliability, therefore they were considered clinically useful. Only five defining characteristics were representative of the association between excess fluid volume and decreased cardiac output. Therefore, excess fluid volume is related to decreased cardiac output, although these diagnoses are not necessarily associated with activity intolerance. The operational definitions may favour early recognition of the sequence of responses to decompensation

  11. Low cardiac output thyroid storm in a girl with Graves' disease.

    PubMed

    Chantra, Marut; Limsuwan, Alisa; Mahachoklertwattana, Pat

    2016-10-01

    A 15-year-old girl with Graves' disease presented with hypotension after methimazole and propranolol were re-started for hyperthyroidism. She was found to have pulmonary artery hypertension resulting in obstructive shock. Thyroid storm was diagnosed according to Burch and Wartofsky score. She was promptly treated with anti-thyroid drugs, inorganic iodide, corticosteroid, and respiratory support. Pulmonary hypertension was treated with inhaled nitric oxide until the clinical status improved. Propranolol was withdrawn due to poor cardiac function. We herein present a unique case of a difficult-to-treat Graves' disease presenting with severe pulmonary hypertension resulting in low cardiac output thyroid storm. © 2016 Japan Pediatric Society.

  12. Noninvasive cardiac output determination for children by the inert gas-rebreathing method.

    PubMed

    Wiegand, Gesa; Kerst, Gunter; Baden, Winfried; Hofbeck, Michael

    2010-11-01

    Standard methods for determination of cardiac output (CO) are either invasive or technically demanding. Measurement of CO by the inert gas-rebreathing (IGR) method, applied successfully in adults, uses a low-concentration mixture of an inert and a blood-soluble gas, respectively. This study tested the feasibility of this method for determining CO during exercise for pediatric patients with complete congenital atrioventricular block (CCAVB) stimulated with a VVI pacemaker. In this study, 5 CCAVB patients (age 9.2-17.4 years) were compared with 10 healthy age-matched boys and girls. Testing was performed with the Innocor system. The patients were instructed to breathe the test gas from a closed system. Pulmonary blood flow was calculated according to the washout of the soluble gas component. During standardized treadmill testing, CO was determined at three defined levels. The CO measurements were successful for all the study participants. The patients reached a lower peak CO than the control subjects (5.9 l/min/m(2) vs 7.3 [boys] and 7.2 [girls]). The stroke volume increase under exercise also was reduced in the patients compared with the control subjects. The feasibility of the IGR method for exercise CO testing in children was documented. Application of the IGR method for children requires careful instruction of the patients and appears restricted to subjects older than 8 years. The method offers new insights into mechanisms of cardiovascular adaptation in children with congenital heart disease.

  13. Clinical review: Guyton--the role of mean circulatory filling pressure and right atrial pressure in controlling cardiac output.

    PubMed

    Henderson, William R; Griesdale, Donald E G; Walley, Keith R; Sheel, A William

    2010-01-01

    Arthur Guyton's concepts of the determinative role of right heart filling in cardiac output continue to be controversial. This paper reviews his seminal experiments in detail and clarifies the often confusing concepts underpinning his model. One primary criticism of Guyton's model is that the parameters describing venous return had not been measured in a functioning cardiovascular system in humans. Thus, concerns have been expressed in regard to the ability of Guyton's simplistic model, with few parameters, to model the complex human circulation. Further concerns have been raised in regard to the artificial experimental preparations that Guyton used. Recently reported measurements in humans support Guyton's theoretical and animal work.

  14. Evaluation of noninvasive exercise cardiac output determination in chronic heart failure patients: a proposal of a new diagnostic and prognostic method.

    PubMed

    Cattadori, Gaia; Salvioni, Elisabetta; Gondoni, Erica; Agostoni, Piergiuseppe

    2011-01-01

    Peak oxygen consumption (VO2) and various parameters of cardiopulmonary response to exercise are of important prognostic value in chronic heart failure patients. However, all the available parameters only indirectly reflect left-ventricular dysfunction and hemodynamic adaptation to an increased demand. Noninvasive assessment of cardiac output, especially during an incremental exercise test, would allow the direct measurement of cardiac reserve and may become the gold standard for prognostic evaluation of chronic heart failure patients.

  15. Diesel Exhaust Inhalation Increases Cardiac Output, Bradyarrhythmias, and Parasympathetic Tone in Aged Heart Failure–Prone Rats

    PubMed Central

    Farraj, Aimen K.

    2013-01-01

    Acute air pollutant inhalation is linked to adverse cardiac events and death, and hospitalizations for heart failure. Diesel engine exhaust (DE) is a major air pollutant suspected to exacerbate preexisting cardiac conditions, in part, through autonomic and electrophysiologic disturbance of normal cardiac function. To explore this putative mechanism, we examined cardiophysiologic responses to DE inhalation in a model of aged heart failure–prone rats without signs or symptoms of overt heart failure. We hypothesized that acute DE exposure would alter heart rhythm, cardiac electrophysiology, and ventricular performance and dimensions consistent with autonomic imbalance while increasing biochemical markers of toxicity. Spontaneously hypertensive heart failure rats (16 months) were exposed once to whole DE (4h, target PM2.5 concentration: 500 µg/m3) or filtered air. DE increased multiple heart rate variability (HRV) parameters during exposure. In the 4h after exposure, DE increased cardiac output, left ventricular volume (end diastolic and systolic), stroke volume, HRV, and atrioventricular block arrhythmias while increasing electrocardiographic measures of ventricular repolarization (i.e., ST and T amplitudes, ST area, T-peak to T-end duration). DE did not affect heart rate relative to air. Changes in HRV positively correlated with postexposure changes in bradyarrhythmia frequency, repolarization, and echocardiographic parameters. At 24h postexposure, DE-exposed rats had increased serum C-reactive protein and pulmonary eosinophils. This study demonstrates that cardiac effects of DE inhalation are likely to occur through changes in autonomic balance associated with modulation of cardiac electrophysiology and mechanical function and may offer insights into the adverse health effects of traffic-related air pollutants. PMID:23047911

  16. Peripartum cardiomyopathy: postpartum decompensation and use of non-invasive cardiac output monitoring.

    PubMed

    Lorello, G; Cubillos, J; McDonald, M; Balki, M

    2014-02-01

    The utility of a non-invasive cardiac output monitor (NICOM™) in guiding the peripartum management and identification of postpartum complications in a patient with severe peripartum cardiomyopathy is reported. A 31-year-old nulliparous woman at 35 weeks of gestation presented with a three-week history of worsening dyspnea and progressive functional deterioration. A transthoracic echocardiogram showed severe left ventricular systolic dysfunction with an ejection fraction <20%. Cardiac status was monitored using NICOM™ during labor and delivery. The baseline values were: cardiac output 5.3 L/min, total peripheral resistance 1549 dynes.sec/cm(5), stroke volume 42.1 mL and stroke volume variation 18%. She received early epidural analgesia during labor, titrated slowly with a loading dose of 0.0625% bupivacaine 10 mL and fentanyl 25 μg, followed by patient-controlled epidural analgesia (0.0625% bupivacaine with fentanyl 2 μg/mL, infusion at 10 mL/h, bolus dose 5 mL and lockout interval 10 min). After epidural drug administration, total peripheral resistance decreased, cardiac output increased, and satisfactory analgesia was obtained. She had an uneventful vaginal delivery with a forceps-assisted second stage after prophylactic administration of furosemide 20 mg. NICOM™ was discontinued after delivery. Fifteen hours post-delivery, the patient developed cardiogenic shock, which resolved after aggressive therapy with inotropes and furosemide. NICOM™ can be used to guide treatment during labor and delivery in patients with critical peripartum cardiomyopathy. We suggest that use of NICOM™ be extended into the postpartum period to detect signs of cardiac decompensation in such patients.

  17. Maternal Cardiac Output and Fetal Doppler Predict Adverse Neonatal Outcomes in Pregnant Women With Heart Disease.

    PubMed

    Wald, Rachel M; Silversides, Candice K; Kingdom, John; Toi, Ants; Lau, Cathy S; Mason, Jennifer; Colman, Jack M; Sermer, Mathew; Siu, Samuel C

    2015-11-23

    The mechanistic basis of the proposed relationship between maternal cardiac output and neonatal complications in pregnant women with heart disease has not been well elucidated. Pregnant women with cardiac disease and healthy pregnant women (controls) were prospectively followed with maternal echocardiography and obstetrical ultrasound scans at baseline, third trimester, and postpartum. Fetal/neonatal complications (death, small-for-gestational-age or low birthweight, prematurity, respiratory distress syndrome, or intraventricular hemorrhage) comprised the primary study outcome. One hundred and twenty-seven women with cardiac disease and 45 healthy controls were enrolled. Neonatal events occurred in 28 pregnancies and were more frequent in the heart disease group as compared with controls (n=26/127 or 21% versus n=2/45 or 4%; P=0.01). Multiple complications in an infant were counted as a single outcome event. Neonatal complications in the heart disease group were small-for-gestational-age/low birthweight (n=18), prematurity (n=14), and intraventricular hemorrhage/respiratory distress syndrome (n=5). Preexisting obstetric risk factors (P=0.003), maternal cardiac output decline from baseline to third trimester (P=0.017), and third trimester umbilical artery Doppler abnormalities (P<0.001) independently predicted neonatal complications and were incorporated into a novel risk index in which 0, 1, and >1 predictor corresponded to expected complication rates of 5%, 30%, and 76%, respectively. Decline in maternal cardiac output during pregnancy and abnormal umbilical artery Doppler flows independently predict neonatal complications. These findings will enhance the identification of higher risk pregnancies that would benefit from close antenatal surveillance. © 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.

  18. Estimation of cardiac output in patients with congestive heart failure by analysis of right ventricular pressure waveforms

    PubMed Central

    2011-01-01

    Background Cardiac output (CO) is an important determinant of the hemodynamic state in patients with congestive heart failure (CHF). We tested the hypothesis that CO can be estimated from the right ventricular (RV) pressure waveform in CHF patients using a pulse contour cardiac output algorithm that considers constant but patient specific RV outflow tract characteristic impedance. Method In 12 patients with CHF, breath-by-breath Fick CO and RV pressure waveforms were recorded utilizing an implantable hemodynamic monitor during a bicycle exercise protocol. These data were analyzed retrospectively to assess changes in characteristic impedance of the RV outflow tract during exercise. Four patients that were implanted with an implantable cardiac defibrillator (ICD) implementing the algorithm were studied prospectively. During a two staged sub-maximal bicycle exercise test conducted at 4 and 16 weeks of implant, COs measured by direct Fick technique and estimated by the ICD were recorded and compared. Results At rest the total pulmonary arterial resistance and the characteristic impedance were 675 ± 345 and 48 ± 18 dyn.s.cm-5, respectively. During sub-maximal exercise, the total pulmonary arterial resistance decreased (Δ 91 ± 159 dyn.s.cm-5, p < 0.05) but the characteristic impedance was unaffected (Δ 3 ± 9 dyn.s.cm-5, NS). The algorithm derived cardiac output estimates correlated with Fick CO (7.6 ± 2.5 L/min, R2 = 0.92) with a limit of agreement of 1.7 L/min and tracked changes in Fick CO (R2 = 0.73). Conclusions The analysis of right ventricular pressure waveforms continuously recorded by an implantable hemodynamic monitor provides an estimate of CO and may prove useful in guiding treatment in patients with CHF. PMID:21569499

  19. Low cardiac output as physiological phenomenon in hibernating, free-ranging Scandinavian brown bears (Ursus arctos) - an observational study.

    PubMed

    Jørgensen, Peter Godsk; Arnemo, Jon; Swenson, Jon E; Jensen, Jan S; Galatius, Søren; Frøbert, Ole

    2014-09-16

    Despite 5-7 months of physical inactivity during hibernation, brown bears (Ursus arctos) are able to cope with physiological conditions that would be detrimental to humans. During hibernation, the tissue metabolic demands fall to 25% of the active state. Our objective was to assess cardiac function associated with metabolic depression in the hibernating vs. active states in free-ranging Scandinavian brown bears. We performed echocardiography on seven free-ranging brown bears in Dalarna, Sweden, anesthetized with medetomidine-zolazepam-tiletamine-ketamine during winter hibernation in February 2013 and with medetomidine-zolazepam-tiletamine during active state in June 2013. We measured cardiac output noninvasively using estimates of hemodynamics obtained by pulsed wave Doppler echocardiography and 2D imaging. Comparisons were made using paired T-tests. During hibernation, all hemodynamic indices were significantly decreased (hibernating vs. active state): mean heart rate was 26.0 (standard deviation (SD): 5.6) beats per min vs. 75.0 (SD: 17.1) per min (P=0.002), mean stroke volume 32.3 (SD: 5.2) ml vs. 47.1 (SD: 7.9) ml (P=0.008), mean cardiac output 0.86 (SD: 0.31) l/min vs. 3.54 (SD: 1.04) l/min (P=0.003), and mean cardiac index 0.63 (SD: 0.21) l/min/kg vs. 2.45 (SD: 0.52) l/min/ m2 (P<0.001). Spontaneous echo contrast was present in all cardiac chambers in all seven bears during hibernation, despite the absence of atrial arrhythmias and valvular disease. Free-ranging brown bears demonstrate hemodynamics comparable to humans during active state, whereas during hibernation, we documented extremely low-flow hemodynamics. Understanding these physiological changes in bears may help to gain insight into the mechanisms of cardiogenic shock and heart failure in humans.

  20. Resistance reconstructed estimation of total peripheral resistance from computationally derived cardiac output - biomed 2013.

    PubMed

    Hill, Labarron K; Sollers Iii, John J; Thayer, Julian F

    2013-01-01

    Efficient functioning of the peripheral vasculature is an essential component in healthy cardiovascular regulation. Alterations in this functioning have been linked to the etiology and pathophysiological course of cardiovascular disease (CVD), especially hypertension. Given its significant role in the maintenance of both healthy and pathological blood pressure, total peripheral resistance (TPR), an index of the vasoconstrictive and elastic properties of the peripheral vasculature, has received much attention in this regard. However, obtaining a reliable estimate of TPR remains a complex and costly endeavor, primarily due to the necessity for sophisticated instrumentation as well as associated limitations in deriving cardiac output (CO). We have previously described a simple estimation method for CO using only arterial blood pressure and heart rate (Hill et al, 2012). In the present study we extend this technique to the estimation of TPR using beat-to-beat blood pressure data from the same sample of 67 young (mean age = 20.04± 2.8), healthy men (n = 30) and women (n = 37). Estimated TPR (TPRest) was calculated from the computationally-derived estimate of CO and mean arterial pressure (MAP). Correlation between TPR obtained via the validated Model-Flow technique and TPRest was moderate (r =.73, p <. 000) and stronger in men (r =.78, p <. 000) compared to women (r =.66, p <. 001). These data further suggest that reconstructed measures of hemodynamic functioning may be validly and adequately estimated from limited data sources.

  1. A novel continuous cardiac output monitor based on pulse wave transit time.

    PubMed

    Sugo, Yoshihiro; Ukawa, Teiji; Takeda, Sunao; Ishihara, Hironori; Kazama, Tomiei; Takeda, Junzo

    2010-01-01

    Monitoring cardiac output (CO) is important for the management of patient circulation in an operation room (OR) or intensive care unit (ICU). We assumed that the change in pulse wave transit time (PWTT) obtained from an electrocardiogram (ECG) and a pulse oximeter wave is correlated with the change in stroke volume (SV), from which CO is derived. The present study reports the verification of this hypothesis using a hemodynamic analysis theory and animal study. PWTT consists of a pre-ejection period (PEP), the pulse transit time through an elasticity artery (T(1)), and the pulse transit time through peripheral resistance arteries (T(2)). We assumed a consistent negative correlation between PWTT and SV under all conditions of varying circulatory dynamics. The equation for calculating SV from PWTT was derived based on the following procedures. 1. Approximating SV using a linear equation of PWTT. 2. The slope and y-intercept of the above equation were determined under consideration of vessel compliance (SV was divided by Pulse Pressure (PP)), animal type, and the inherent relationship between PP and PWTT. Animal study was performed to verify the above-mentioned assumption. The correlation coefficient of PWTT and SV became r = -0.710 (p 〈 0.001), and a good correlation was admitted. It has been confirmed that accurate continuous CO and SV measurement is only possible by monitoring regular clinical parameters (ECG, SpO2, and NIBP).

  2. Characteristics of cardiac troponin measurements.

    PubMed

    Christenson, Eric; Christenson, Robert H

    2013-12-01

    Cardiac troponin I (cTnI) and T (cTnT) have displaced myoglobin and creatine kinase-MB as the preferred markers of myocardial injury and have become the cornerstones for diagnosis of myocardial infarction (MI). Current guidelines for MI diagnosis give specific recommendations for cTnI and cTnT assays including instructions to reliably measure values in the range of the 99th percentile of a normal reference cohort with good precision, for example, 10% total coefficient of variation. Unfortunately, the nomenclature system that has evolved for cTnI and cTnT is haphazard and unsystematic. It is key to recognize that not all cTnI and cTnT measurement methods are equivalent; hence, knowledge of local measurements is essential for effective evaluation of patients presenting with suspected non-ST elevation MI. For cTnI, the amino acid sequences frequently targeted for effective measurement include residues 41-49 and 83-93 because these regions of the molecule are stable, helping make the assays reproducible. Use of the recommended cutoff at the 99th percentile of a normal cohort is related to improved patient outcomes. Therefore, use of a troponin assay with good measurement characteristics at the 99th percentile, often referred to as 'sensitive assays', is important for patient outcomes. cTnI and cTnT assays with higher sensitivity are becoming available, and their utilization for measurement in asymptomatic populations may be useful for risk assessment and management in the future. However there is currently no evidence that these high-sensitivity assays confer an advantage in the context of MI diagnosis. Currently cTnI assays are not standardized; thus, there can be a substantial difference in values depending on the assay used. An international effort toward standardization is ongoing, but is not anticipated to be completed and implemented for a few years. Our purpose here is to add insight to important characteristics of troponin measurement techniques and how these

  3. Jet and ultrasonic nebuliser output: use of a new method for direct measurement of aerosol output.

    PubMed Central

    Dennis, J H; Stenton, S C; Beach, J R; Avery, A J; Walters, E H; Hendrick, D J

    1990-01-01

    Output from jet nebulisers is calibrated traditionally by weighing them before and after nebulisation, but the assumption that the weight difference is a close measure of aerosol generation could be invalidated by the concomitant process of evaporation. A method has been developed for measuring aerosol output directly by using a solute (fluoride) tracer and aerosol impaction, and this has been compared with the traditional weight loss method for two Wright, six Turbo, and four Micro-Cirrus jet nebulisers and two Microinhaler ultrasonic nebulisers. The weight loss method overestimated true aerosol output for all jet nebulisers. The mean aerosol content, expressed as a percentage of the total weight loss, varied from as little as 15% for the Wright jet nebulisers to 54% (range 45-61%) for the Turbo and Micro-Cirrus jet nebulisers under the operating conditions used. In contrast, there was no discrepancy between weight loss and aerosol output for the ultrasonic nebulisers. These findings, along with evidence of both concentrating and cooling effects from jet nebulisation, confirm that total output from jet nebulisers contains two distinct fractions, vapour and aerosol. The vapour fraction, but not the aerosol fraction, was greatly influenced by reservoir temperature within the nebuliser; so the ratio of aerosol output to total weight loss varied considerably with temperature. It is concluded that weight loss is an inappropriate method of calibrating jet nebuliser aerosol output, and that this should be measured directly. PMID:2247862

  4. Significant correlation of comprehensive Aristotle score with total cardiac output during the early postoperative period after the Norwood procedure.

    PubMed

    Li, Jia; Zhang, Gencheng; Holtby, Helen; Cai, Sally; Walsh, Mark; Caldarone, Christopher A; Van Arsdell, Glen S

    2008-07-01

    The comprehensive Aristotle score has been proposed as an individualized measure of the complexity of a given surgical procedure and has been reported to significantly correlate with postoperative morbidity and mortality after the Norwood procedure. An important factor leading to postoperative morbidity and mortality is low cardiac output. We studied the correlation between the comprehensive Aristotle score and cardiac output (CO) in infants after the Norwood procedure. Respiratory mass spectrometry was used to continuously measure systemic oxygen consumption (VO(2)) in 22 infants for 72 hours postoperatively. Arterial, superior vena caval and pulmonary venous blood gases were measured at 2 to 4 hour intervals to calculate CO. The comprehensive Aristotle score was collected. Hospital mortality was 4.5%. The comprehensive Aristotle score ranged from 14.5 to 23.5 and negatively correlated with CO (P = 0.027). Among the patient-adjusted factors, myocardial dysfunction (n = 10), mechanical ventilation to treat cardiorespiratory failure (n = 9) and atrioventricular valve regurgitation (n = 4) (P = 0.01) negatively correlated with CO (P = 0.06 to 0.07). Aortic atresia (n = 9) was associated with a lower CO (P = 0.01) for the first 24 hours which linearly increased overtime (P = 0.0001). No correlation was found between CO and other factors (P > 0.3 for all). Comprehensive Aristotle score significantly negatively correlates with CO after the Norwood procedure. A preoperative estimation of the comprehensive Aristotle score, particularly in association with myocardial dysfunction, mechanical ventilation to treat cardiorespiratory failure, atrioventricular valve regurgitation and aortic atresia may help to anticipate a high postoperative morbidity with low cardiac output syndrome.

  5. Determining arterial pressure, left atrial pressure and cardiac output from the left pneumatic drive line of the total artificial heart.

    PubMed

    Rosenberg, G; Landis, D L; Phillips, W M; Stallsmith, J; Pierce, W S

    1978-01-01

    These data presented here demonstrate how careful analysis of mock loop testing can lead to useful measurements for long-term calf experiments. The accuracy of the data rae primarily dependent upon a valid circulatory system analog and good experimental technique. These methods of determining arterial pressure, left atrial pressure and cardiac output have allowed us to obtain recordds of these important parameters for periods as long as 100 days in calves with total artificial heart implantation. These methods have also enabled us to automatically control the artifical heart under conditions of rest, exercise and pharmacologic treatment with the use of only one external pneumatic drive line pressure transducer.

  6. [Antianginal efficacy of ivabradine in a very old patient with aortic stenosis: effects on cardiac output and transvalvular aortic gradients].

    PubMed

    Nervo, Elisabetta; Menditto, Elena; Taglieri, Camillo; Lombardo, Enrico; Piccolo, Salvatore; Feola, Mauro

    2010-09-01

    Ivabradine is a selective I(f) current inhibitor in the sinus node that decreases heart rate without negative inotropic effects. We report the case of an 88-year-old diabetic patient with arterial hypertension and peripheral arterial disease who experienced an antero-lateral non-ST-elevation myocardial infarction following post-surgical anemia. After admission, the patient complained of anginal pain at rest with ischemic alterations of ST-T at the ECG and mild increase in troponin T levels. According to the clinical status, the association of ivabradine with beta-blockers was started. The addition of ivabradine reduced heart rate, improved symptoms (CCS class I-II) without modifying the main hemodynamic (non-invasively measured cardiac output, stroke volume and cardiac index) and echocardiographic parameters (left ventricular ejection fraction and aortic transvalvular gradients). In conclusion, the antianginal effect of ivabradine seems to be sure in very old ischemic patients with aortic stenosis.

  7. Cooperative linear output regulation for networked systems by dynamic measurement output feedback

    NASA Astrophysics Data System (ADS)

    Li, Shaobao; Feng, Gang; Wang, Juan; Luo, Xiaoyuan; Guan, Xinping

    2016-04-01

    This paper investigates the cooperative linear output regulation problem of a class of heterogeneous networked systems with a common reference input but with different disturbances for individual nodes. A novel distributed control law is presented based on dynamic measurement output feedback. It is shown that the overall networked closed-loop control system is asymptotically stable and the output regulation errors asymptotically approach zero as time goes to infinity under a sufficient and necessary condition. Finally, a numerical example is provided to demonstrate the effectiveness of the proposed control law.

  8. Preoperative thromboelastometry for the prediction of increased chest tube output in cardiac surgery: A retrospective study.

    PubMed

    Gozdzik, Waldemar; Adamik, Barbara; Wysoczanski, Grzegorz; Gozdzik, Anna; Rachwalik, Maciej; Skalec, Tomasz; Kübler, Andrzej

    2017-07-01

    Bleeding following cardiac surgery is a serious event with potentially life-threatening consequences. Preoperative recognition of coagulation abnormalities and detection of cardiopulmonary bypass (CPB) related coagulopathy could aid in the start of preventive treatment strategies that minimize perioperative blood loss. Most algorithms that analyze thromboelastometry coagulation tests in elective cardiac surgery do not include test results performed before surgery. We evaluated preoperative rotational thromboelastometry test results for their ability to predict blood loss during and after cardiac surgery.A total of 114 adult patients undergoing cardiac surgery with CPB were included in this retrospective analysis. Each patient had thromboelastometry tests done twice: preoperatively, before the induction of anesthesia and postoperatively, 10 minutes after heparin reversal with protamine after decannulation.Patients were placed into 1 of 2 groups depending on whether preoperative thromboelastometry parameters deviated from reference ranges: Group 1 [N = 29; extrinsically activated test (EXTEM) or INTEM results out of normal range] or Group 2 (N = 85; EXTEM and INTEM results within the normal range). We observed that the total amount of chest tube output was significantly greater in Group 1 than in Group 2 (700 mL vs 570 mL, P = .03). At the same time, the preoperative values of standard coagulation tests such as platelet count, aPTT, and INR did not indicate any abnormalities of coagulation.Preoperative coagulation abnormalities diagnosed with thromboelastometry can predict increased chest tube output in the early postoperative period in elective adult cardiac surgery. Monitoring of the coagulation system with thromboelastometry allows rapid diagnosis of coagulation abnormalities even before the start of the surgery. These abnormalities could not always be detected with routine coagulation tests.

  9. The comparison of a novel continuous cardiac output monitor based on pulse wave transit time and echo Doppler during exercise.

    PubMed

    Sugo, Yoshihiro; Sakai, Tomoyuki; Terao, Mami; Ukawa, Teiji; Ochiai, Ryoichi

    2012-01-01

    A new technology called estimated continuous cardiac output (esCCO) uses pulse wave transit time (PWTT) obtained from an electrocardiogram and pulse oximeter to measure cardiac output (CO) non-invasively and continuously. This study was performed to evaluate the accuracy of esCCO during exercise testing. We compared esCCO with CO measured by the echo Doppler aortic velocity-time integral (VTIao_CO). The correlation coefficient between esCCO and VTIao_CO was r= 0.87 (n= 72). Bias and precision were 0.33 ± 0.95 L/min and percentage error was 31%. The esCCO could detect change in VTIao_CO larger than 1 L/min with a concordance rate of 88%. In polar plot, 83% of data are within 0.5 L/min, and 100% of data are within 1 L/min. Those results show the acceptable accuracy and trend ability of esCCO. Change in pre-ejection period (PEP) measured by using M-mode of Diagnostic Ultrasound System accounted for approximately half of change in PWTT. This indicates that PEP included in PWTT has an impact on the accuracy of esCCO measurement. In this study, the validity of esCCO during exercise testing was assessed and shown to be acceptable. The result of this study suggests that we can expand its application.

  10. Noninvasive measurement of cardiac performance in recovery from exercise in heart failure patients

    PubMed Central

    Myers, Jonathan N; Gujja, Pradeep; Neelagaru, Suresh; Hsu, Leon; Burkhoff, Daniel

    2011-01-01

    OBJECTIVE: To examine the association between cardiac performance during recovery and the severity of heart failure, as determined by clinical and cardiopulmonary exercise test responses. METHODS: As part of a retrospective cohort study, 46 heart failure patients and 13 normal subjects underwent cardiopulmonary exercise testing while cardiac output was measured using a noninvasive device. Cardiac output in recovery was expressed as the slope of a single exponential relationship between cardiac output and time; the recovery-time constant was assessed in relation to indices of cardiac function, along with clinical, functional, and cardiopulmonary exercise responses. RESULTS: The recovery time constant was delayed in patients with heart failure compared with normal subjects (296.7±238 vs. 110.1±27 seconds, p <0.01), and the slope of the decline of cardiac output in recovery was steeper in normal subjects compared with heart failure patients (p<0.001). The slope of the decline in cardiac output recovery was inversely related to peak VO2 (r = -0.72, p<0.001) and directly related to the VE/VCO2 slope (r = 0.57, p<0.001). Heart failure patients with abnormal recovery time constants had lower peak VO2, lower VO2 at the ventilatory threshold, lower peak cardiac output, and a heightened VE/VCO2 slope during exercise. CONCLUSIONS: Impaired cardiac output recovery kinetics can identify heart failure patients with more severe disease, lower exercise capacity, and inefficient ventilation. Estimating cardiac output in recovery from exercise may provide added insight into the cardiovascular status of patients with heart failure. PMID:21655761

  11. Does targeted pre-load optimisation by stroke volume variation attenuate a reduction in cardiac output in the prone position.

    PubMed

    Wu, C-Y; Lee, T-S; Chan, K-C; Jeng, C-S; Cheng, Y-J

    2012-07-01

    The prone position can reduce cardiac output by up to 25% due to reduced preload. We hypothesised that preload optimisation targeted to stroke volume variation before turning prone might alleviate this. A supine threshold stroke volume variation of 14% in a preliminary study identified patients whose cardiac outputs would decline when turned prone. In 45 patients, cardiac output declined only in the group whose supine stroke volume variation was high (mean (SD) 5.1 (2.0) to 3.9 (1.9) l.min(-1) ; p < 0.001), but not in patients in whom it was low, or in those in whom stroke volume variation was high, but who received volume preload (p = 0.525 and 0.941, respectively). We conclude that targeted preload optimisation using a supine stroke volume variation value < 14% is effective in preventing falls in cardiac output induced by the prone position.

  12. Caveolae protect endothelial cells from membrane rupture during increased cardiac output

    PubMed Central

    Cheng, Jade P.X.; Mendoza-Topaz, Carolina; Howard, Gillian; Chadwick, Jessica; Shvets, Elena; Cowburn, Andrew S.; Dunmore, Benjamin J.; Crosby, Alexi; Morrell, Nicholas W.

    2015-01-01

    Caveolae are strikingly abundant in endothelial cells, yet the physiological functions of caveolae in endothelium and other tissues remain incompletely understood. Previous studies suggest a mechanoprotective role, but whether this is relevant under the mechanical forces experienced by endothelial cells in vivo is unclear. In this study we have sought to determine whether endothelial caveolae disassemble under increased hemodynamic forces, and whether caveolae help prevent acute rupture of the plasma membrane under these conditions. Experiments in cultured cells established biochemical assays for disassembly of caveolar protein complexes, and assays for acute loss of plasma membrane integrity. In vivo, we demonstrate that caveolae in endothelial cells of the lung and cardiac muscle disassemble in response to acute increases in cardiac output. Electron microscopy and two-photon imaging reveal that the plasma membrane of microvascular endothelial cells in caveolin 1−/− mice is much more susceptible to acute rupture when cardiac output is increased. These data imply that mechanoprotection through disassembly of caveolae is important for endothelial function in vivo. PMID:26459598

  13. Improved hepatic arterial fraction estimation using cardiac output correction of arterial input functions for liver DCE MRI

    NASA Astrophysics Data System (ADS)

    Chouhan, Manil D.; Bainbridge, Alan; Atkinson, David; Punwani, Shonit; Mookerjee, Rajeshwar P.; Lythgoe, Mark F.; Taylor, Stuart A.

    2017-02-01

    Liver dynamic contrast enhanced (DCE) MRI pharmacokinetic modelling could be useful in the assessment of diffuse liver disease and focal liver lesions, but is compromised by errors in arterial input function (AIF) sampling. In this study, we apply cardiac output correction to arterial input functions (AIFs) for liver DCE MRI and investigate the effect on dual-input single compartment hepatic perfusion parameter estimation and reproducibility. Thirteen healthy volunteers (28.7  ±  1.94 years, seven males) underwent liver DCE MRI and cardiac output measurement using aortic root phase contrast MRI (PCMRI), with reproducibility (n  =  9) measured at 7 d. Cardiac output AIF correction was undertaken by constraining the first pass AIF enhancement curve using the indicator-dilution principle. Hepatic perfusion parameters with and without cardiac output AIF correction were compared and 7 d reproducibility assessed. Differences between cardiac output corrected and uncorrected liver DCE MRI portal venous (PV) perfusion (p  =  0.066), total liver blood flow (TLBF) (p  =  0.101), hepatic arterial (HA) fraction (p  =  0.895), mean transit time (MTT) (p  =  0.646), distribution volume (DV) (p  =  0.890) were not significantly different. Seven day corrected HA fraction reproducibility was improved (mean difference 0.3%, Bland-Altman 95% limits-of-agreement (BA95%LoA)  ±27.9%, coefficient of variation (CoV) 61.4% versus 9.3%, ±35.5%, 81.7% respectively without correction). Seven day uncorrected PV perfusion was also improved (mean difference 9.3 ml min-1/100 g, BA95%LoA  ±506.1 ml min-1/100 g, CoV 64.1% versus 0.9 ml min-1/100 g, ±562.8 ml min-1/100 g, 65.1% respectively with correction) as was uncorrected TLBF (mean difference 43.8 ml min-1/100 g, BA95%LoA  ±586.7 ml min-1/ 100 g, CoV 58.3% versus 13.3 ml min-1/100 g, ±661.5 ml min-1/100 g, 60.9% respectively with correction

  14. Cardiac remodeling and increased central venous pressure underlie elevated stroke volume and cardiac output of seawater-acclimated rainbow trout.

    PubMed

    Brijs, Jeroen; Sandblom, Erik; Dekens, Esmée; Näslund, Joacim; Ekström, Andreas; Axelsson, Michael

    2017-01-01

    Substantial increases in cardiac output (CO), stroke volume (SV), and gastrointestinal blood flow are essential for euryhaline rainbow trout (Oncorhyncus mykiss) osmoregulation in seawater. However, the underlying hemodynamic mechanisms responsible for these changes are unknown. By examining a range of circulatory and cardiac morphological variables of seawater- and freshwater-acclimated rainbow trout, the present study revealed a significantly higher central venous pressure (CVP) in seawater-acclimated trout (~0.09 vs. -0.02 kPa). This serves to increase cardiac end-diastolic volume in seawater and explains the elevations in SV (~0.41 vs. 0.27 ml/kg) and CO (~21.5 vs. 14.2 ml·min(-1)·kg(-1)) when compared with trout in freshwater. Furthermore, these hemodynamic modifications coincided with a significant increase in the proportion of compact myocardium, which may be necessary to compensate for the increased wall tension associated with a larger stroke volume. Following a temperature increase from 10 to 16.5°C, both acclimation groups exhibited similar increases in heart rate (Q10 of ~2), but SV tended to decrease in seawater-acclimated trout despite the fact that CVP was maintained in both groups. This resulted in CO of seawater- and freshwater-acclimated trout stabilizing at a similar level after warming (~26 ml·min(-1)·kg(-1)). The consistently higher CVP of seawater-acclimated trout suggests that factors other than compromised cardiac filling constrained the SV and CO of these individuals at high temperatures. The present study highlights, for the first time, the complex interacting effects of temperature and water salinity on cardiovascular responses in a euryhaline fish species. Copyright © 2017 the American Physiological Society.

  15. Serum cortisol concentration with exploratory cut-off values do not predict the effects of hydrocortisone administration in children with low cardiac output after cardiac surgery.

    PubMed

    Verweij, E J; Hogenbirk, Karin; Roest, Arno A W; van Brempt, Ronald; Hazekamp, Mark G; de Jonge, Evert

    2012-10-01

    Low cardiac output syndrome is common after paediatric cardiac surgery. Previous studies suggested that hydrocortisone administration may improve haemodynamic stability in case of resistant low cardiac output syndrome in critically ill children. This study was set up to test the hypothesis that the effects of hydrocortisone on haemodynamics in children with low cardiac output syndrome depend on the presence of (relative) adrenal insufficiency. A retrospective study was done on paediatric patients who received hydrocortisone when diagnosed with resistant low cardiac output syndrome after paediatric cardiac surgery in the period from 1 November 2005 to 31 December 2008. We studied the difference in effects of treatment with hydrocortisone administration between patients with adrenal insufficiency defined as an exploratory cut-off value of total cortisol of <100 nmol/l and patients with a serum total cortisol of ≥ 100 nmol/l. A total of 62 of patients were enrolled, meeting the inclusion criteria for low cardiac output syndrome. Thirty-two patients were assigned to Group 1 (<100 nmol/l) and 30 were assigned to Group 2 (≥ 100 nmol/l). Haemodynamics improved after hydrocortisone administration, with an increase in blood pressure, a decrease in administered vasopressors and inotropic drugs, an increase in urine production and a decrease in plasma lactate concentrations. The effects of treatment with hydrocortisone in children with low cardiac output after cardiac surgery was similar in patients with a low baseline serum cortisol concentration and those with normal baseline cortisol levels. A cortisol value using an exploratory cut-off value of 100 nmol/l for adrenal insufficiency should not be used as a criterion to treat these patients with hydrocortisone.

  16. Effect of betaxolol on the hemodynamic, gas exchange, and cardiac output response to exercise in chronic atrial fibrillation.

    PubMed

    Atwood, J E; Myers, J; Quaglietti, S; Grumet, J; Gianrossi, R; Umman, T

    1999-04-01

    beta-blockade controls the ventricular response to exercise in chronic atrial fibrillation (AF), but the effects of beta-blockers on exercise capacity in AF have been debated. Twelve men with AF (65+/-8 years) participated in a randomized, double-blind, placebo-controlled study of betaxolol (20 mg daily). Patients underwent maximal exercise testing with ventilatory gas exchange analysis, and a separate, submaximal test (50% of maximum) during which cardiac output was measured by a CO2 rebreathing technique. After betaxolol therapy, heart rate was reduced both at rest (92+/-27 vs 62+/-12 beats/min; p < 0.001) and at peak exercise (173+/-22 vs 116+/-24 beats/min; p < 0.001). Maximal oxygen uptake (VO2) was reduced by 19% after betaxolol (21.8+/-5.3 with placebo vs 17.6+/-5.1 mL/kg/min with betaxolol; p < 0.05), with similar reductions observed for maximal exercise time, minute ventilation, and CO2 production. VO2 was reduced by a similar extent (19%) at the ventilatory threshold. Submaximal cardiac output was reduced by 15% during betaxolol therapy (12.9+/-2.3 vs 10.9+/-1.3 L/min; p < 0.05), and stroke volume was higher (88.0+/-21 vs 105.6+/-19 mL/beat; p < 0.05). Betaxolol therapy in patients with AF effectively controlled the ventricular rate at rest and during exercise, but also caused considerable reductions in maximal VO2 and cardiac output during exercise. The observed increase in stroke volume could not adequately compensate for reduced heart rate to maintain VO2 during exercise.

  17. At high cardiac output, diesel exhaust exposure increases pulmonary vascular resistance and decreases distensibility of pulmonary resistive vessels.

    PubMed

    Wauters, Aurélien; Vicenzi, Marco; De Becker, Benjamin; Riga, Jean-Philippe; Esmaeilzadeh, Fatemeh; Faoro, Vitalie; Vachiéry, Jean-Luc; van de Borne, Philippe; Argacha, Jean-François

    2015-12-15

    Air pollution has recently been associated with the development of acute decompensated heart failure, but the underlying biological mechanisms remain unclear. A pulmonary vasoconstrictor effect of air pollution, combined with its systemic effects, may precipitate decompensated heart failure. The aim of the present study was to investigate the effects of acute exposure to diesel exhaust (DE) on pulmonary vascular resistance (PVR) under resting and stress conditions but also to determine whether air pollution may potentiate acquired pulmonary hypertension. Eighteen healthy male volunteers were exposed to ambient air (AA) or dilute DE with a particulate matter of <2.5 μm concentration of 300 μg/m(3) for 2 h in a randomized, crossover study design. The effects of DE on PVR, on the coefficient of distensibilty of pulmonary vessels (α), and on right and left ventricular function were evaluated at rest (n = 18), during dobutamine stress echocardiography (n = 10), and during exercise stress echocardiography performed in hypoxia (n = 8). Serum endothelin-1 and fractional exhaled nitric oxide were also measured. At rest, exposure to DE did not affect PVR. During dobutamine stress, the slope of the mean pulmonary artery pressure-cardiac output relationship increased from 2.8 ± 0.5 mmHg · min · l (-1) in AA to 3.9 ± 0.5 mmHg · min · l (-1) in DE (P < 0.05) and the α coefficient decreased from 0.96 ± 0.15 to 0.64 ± 0.12%/mmHg (P < 0.01). DE did not further enhance the hypoxia-related upper shift of the mean pulmonary artery pressure-cardiac output relationship. Exposure to DE did not affect serum endothelin-1 concentration or fractional exhaled nitric oxide. In conclusion, acute exposure to DE increased pulmonary vasomotor tone by decreasing the distensibility of pulmonary resistive vessels at high cardiac output. Copyright © 2015 the American Physiological Society.

  18. Against Journal Articles for Measuring Value in University Output

    ERIC Educational Resources Information Center

    Mbali, C.

    2010-01-01

    The following lines of arguments against the metrics of journal articles is developed: (1) Textual output should no longer be main valued output; (2) Digitalization enables other ways of advancing knowledge; (3) Measures by journal article favours the disciplines of Natural Science and Engineering (NSE) and moulds other disciplines of Social…

  19. [Relation between oxygen consumption and cardiac output during inhalation anesthesia under the influence of catecholamines. A study in dogs].

    PubMed

    Scheeren, T W

    2000-04-01

    The metabolic regulation of tissue blood flow manifests itself in a linear relation between blood flow and oxygen consumption (VO2). It is unknown, however, if this fundamental physiological principle operates also during inhalation anaesthesia and catecholamine therapy, both known to be associated with changes of cardiac output (Q) and VO2 in opposite directions. On different days, 17 trained, healthy dogs (26-33 kg) with chronically implanted flow probes around the pulmonary artery were either anaesthetized with halothane, enflurane, isoflurane, sevoflurane, and desflurane at increasing minimum alveolar concentrations (1-3 MAC) or treated with one of the endogenous catecholamines epinephrine and norepinephrine or the synthetic ones dobutamine and dopexamine (a total of 186 experiments). Cardiac Output (ultrasound transit-time flowmeter) and VO2 (indirect calorimetry) were measured continuously and the relations between both variables (Q/VO2 relations) analyzed. In awake dogs under basal metabolic conditions, VO2 was 4.6 +/- 0.1 ml x kg-1 x min-1 and Q 105 +/- 3 ml x kg-1 x min-1 (mean +/- SEM). During inhalation anaesthesia, VO2 and Q decreased in parallel, yielding a uniform Q/VO2 relation, which was nearly linear. Above 2 MAC, O2 extraction increased by 50%, indicating compromised oxygen delivery (DO2). Imposed increases in Q and thus DO2 during anaesthesia to rates comparable to that in the awake state did not restore VO2 to baseline. Catecholamines increased both VO2 and Q in a dose-dependent manner, albeit to a different extent. The resulting Q/VO2 relations were linear up to the maximum effects, but their slopes increased about threefold in the order norepinephrine (34), epinephrine (54), dobutamine (86), and dopexamine (105). Despite these differences, VO2 and Q correlated linearly over the whole range studied, which covered a doubling of VO2 and an up to fourfold increase in Q. The metabolic regulation of blood flow apparently also operates during

  20. Impact of extracorporeal blood flow rate on blood pressure, pulse rate and cardiac output during haemodialysis.

    PubMed

    Schytz, Philip Andreas; Mace, Maria Lerche; Soja, Anne Merete Boas; Nilsson, Brian; Karamperis, Nikolaos; Kristensen, Bent; Ladefoged, Søren Daustrand; Hansen, Henrik Post

    2015-12-01

    If blood pressure (BP) falls during haemodialysis (HD) [intradialytic hypotension (IDH)] a common clinical practice is to reduce the extracorporeal blood flow rate (EBFR). Consequently the efficacy of the HD (Kt/V) is reduced. However, only very limited knowledge on the effect of reducing EBFR on BP exists and data are conflicting. The aim of this study was to evaluate the effect and the potential mechanism(s) involved by investigating the impact of changes in EBFR on BP, pulse rate (PR) and cardiac output (CO) in HD patients with arteriovenous-fistulas (AV-fistulas). We performed a randomized, crossover trial in 22 haemodynamically stable HD patients with AV-fistula. After a conventional HD session each patient was examined during EBFR of 200, 300 and 400 mL/min in random order. After 15 min when steady state was achieved CO, BP and PR were measured at each EFBR, respectively. Mean (SD) age was 71 (11) years. Systolic BP was significantly higher at an EBFR of 200 mL/min as compared with 300 mL/min [133 (23) versus 128 (24) mmHg; P < 0.05], but not as compared with 400 mL/min [133 (23) versus 130 (19) mmHg; P = 0.20]. At EBFR of 200, 300 and 400 mL/min diastolic BP, mean arterial pressure, PR and CO remained unchanged. Our study does not show any consistent trend in BP changes by a reduction in EBFR. Reduction in EBFR if BP falls during IDH is thus not supported. However, none of the patients experienced IDH. Further studies are required to evaluate the impact of changes in EBFR on BP during IDH. © The Author 2015. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.

  1. Spontaneous baroreflex control of cardiac output during dynamic exercise, muscle metaboreflex activation, and heart failure.

    PubMed

    Ichinose, Masashi; Sala-Mercado, Javier A; O'Leary, Donal S; Hammond, Robert L; Coutsos, Matthew; Ichinose, Tomoko; Pallante, Marco; Iellamo, Ferdinando

    2008-03-01

    We have previously shown that spontaneous baroreflex-induced changes in heart rate (HR) do not always translate into changes in cardiac output (CO) at rest. We have also shown that heart failure (HF) decreases this linkage between changes in HR and CO. Whether dynamic exercise and muscle metaboreflex activation (via imposed reductions in hindlimb blood flow) further alter this translation in normal and HF conditions is unknown. We examined these questions using conscious, chronically instrumented dogs before and after pacing-induced HF during mild and moderate dynamic exercise with and without muscle metaboreflex activation. We measured left ventricular systolic pressure (LVSP), CO, and HR and analyzed the spontaneous HR-LVSP and CO-LVSP relationships. In normal animals, mild exercise significantly decreased HR-LVSP (-3.08 +/- 0.5 vs. -5.14 +/- 0.6 beats.min(-1).mmHg(-1); P < 0.05) and CO-LVSP (-134.74 +/- 24.5 vs. -208.6 +/- 22.2 ml.min(-1).mmHg(-1); P < 0.05). Moderate exercise further decreased both and, in addition, significantly reduced HR-CO translation (25.9 +/- 2.8% vs. 52.3 +/- 4.2%; P < 0.05). Muscle metaboreflex activation at both workloads decreased HR-LVSP, whereas it had no significant effect on CO-LVSP and the HR-CO translation. HF significantly decreased HR-LVSP, CO-LVSP, and the HR-CO translation in all situations. We conclude that spontaneous baroreflex HR responses do not always cause changes in CO during exercise. Moreover, muscle metaboreflex activation during mild and moderate dynamic exercise reduces this coupling. In addition, in HF the HR-CO translation also significantly decreases during both workloads and decreases even further with muscle metaboreflex activation.

  2. Cardiac output distribution in miniature swine during locomotory exercise to VO/sub 3max/

    SciTech Connect

    Armstrong, R.B.; Delp, M.D.; Laughlin, M.H.

    1986-03-01

    Distribution of cardiac output (CO) was studied in miniature swine (22 +/- 1 kg) during level treadmill exercise up to the speed (17.7 km/hr) that elicited maximal oxygen consumption (VO/sub 2max/) (60 +/- 4 m1/min/kg). COs and tissue blood flows (BFs) were measured with the radiolabelled microsphere technique. CO increased from a preexercise value of 2.1 +/- 0.5 1/min up to 9.9 +/- 0.5 1/min at VO/sub 2max/. In preexercise standing 43% of CO went to skeletal muscle, which comprised 36 +/- 1% of body mass, 42% to viscera (12 +/- 1% mass), 5% to brain, heart, and lungs (2% +/- 0.1% mass), and 10% to skin and skeleton (35 +/- 2% mass). Preexercise could not be considered resting because of the animals' excitability. Skeletal muscle BF increased progressively with speed up to VO/sub 2max/, both in absolute terms and in percent CO. At VO/sub 2max/, 88% of CO went to muscle, 3% to viscera, 8% to brain, heart and lungs, and 1% to skin and skeleton. Thus, at VO/sub 2max/ only 4% of CO went to the inactive tissues, which constituted 47% of body mass. In 2 pigs that ran at speeds above 17 km/hr, total muscle BF leveled off at VO/sub 2max/. These findings demonstrate that muscle BF progressively increases up to VO/sub 2max/, and that VO/sub 2/ levels off at the same intensity as muscle flow.

  3. On- and off-exercise kinetics of cardiac output in response to cycling and walking in COPD patients with GOLD Stages I-IV.

    PubMed

    Vasilopoulou, M K; Vogiatzis, I; Nasis, I; Spetsioti, S; Cherouveim, E; Koskolou, M; Kortianou, E A; Louvaris, Z; Kaltsakas, G; Koutsoukou, A; Koulouris, N G; Alchanatis, M

    2012-05-31

    Exercise-induced dynamic hyperinflation and large intrathoracic pressure swings may compromise the normal increase in cardiac output (Q) in Chronic Obstructive Pulmonary Disease (COPD). Therefore, it is anticipated that the greater the disease severity, the greater would be the impairment in cardiac output during exercise. Eighty COPD patients (20 at each GOLD Stage) and 10 healthy age-matched individuals undertook a constant-load test on a cycle-ergometer (75% WR(peak)) and a 6min walking test (6MWT). Cardiac output was measured by bioimpedance (PhysioFlow, Enduro) to determine the mean response time at the onset of exercise (MRTon) and during recovery (MRToff). Whilst cardiac output mean response time was not different between the two exercise protocols, MRT responses during cycling were slower in GOLD Stages III and IV compared to Stages I and II (MRTon: Stage I: 45±2, Stage II: 65±3, Stage III: 90±3, Stage IV: 106±3s; MRToff: Stage I: 42±2, Stage II: 68±3, Stage III: 87±3, Stage IV: 104±3s, respectively). In conclusion, the more advanced the disease severity the more impaired is the hemodynamic response to constant-load exercise and the 6MWT, possibly reflecting greater cardiovascular impairment and/or greater physical deconditioning.

  4. A comparison of the changes in cardiac output and systemic vascular resistance during exercise following high-fat meals containing DHA or EPA.

    PubMed

    Rontoyanni, Victoria G; Hall, Wendy L; Pombo-Rodrigues, Sonia; Appleton, Amber; Chung, Roxanna; Sanders, Thomas A B

    2012-08-01

    Long-chain n-3 PUFA can lower blood pressure (BP) but their acute effects on cardiac output, BP and systemic vascular resistance (SVR) in response to dynamic exercise are uncertain. We compared the effects of high-fat meals rich in EPA (20 : 5n-3), DHA (22 : 6n-3) or oleic acid (control) on cardiac output, BP and SVR in response to exercise stress testing. High-fat meals (50 g fat) containing high-oleic sunflower oil enriched with 4·7 g of either EPA or DHA v. control (high-oleic sunflower oil only) were fed to twenty-two healthy males using a randomised cross-over design. Resting measurements of cardiac output, heart rate and BP were made before and hourly over 5 h following the meal. A standardised 12 min exercise test was then conducted with further measurements made during and post-exercise. Blood samples were collected at fasting, 5 h postprandially and immediately post-exercise for the analysis of lipid, glucose and 8-isoprostane-F2α (8-iso-PGF2α). Plasma concentrations of EPA and DHA increased by 0·22 mmol/l 5 h following the EPA and DHA meals, respectively, compared with the control (P < 0·001). Resting cardiac output and 8-iso-PGF2α increased similarly following all meals and there were no significant differences in cardiac output during exercise between the meals. SVR was lower at 5 h and during exercise following the DHA but not EPA meal, compared with the control meal, by 4·9 % (95 % CI 1·3, 8·4; P < 0·01). Meals containing DHA appear to differ from EPA with regard to their effects on cardiovascular haemodynamics during exercise.

  5. Cardiac output, oxygen consumption and arteriovenous oxygen difference following a sudden rise in exercise level in humans.

    PubMed Central

    De Cort, S C; Innes, J A; Barstow, T J; Guz, A

    1991-01-01

    1. To investigate the relative contributions of increases in cardiac output and arteriovenous oxygen difference to the increase in oxygen consumption during exercise, the ventilatory and cardiovascular responses to a sudden transition from unloaded cycling to 70 or 80 W were measured in six normal healthy subjects. 2. Oxygen consumption (VO2) was measured breath-by-breath and corrected for changes in lung gas stores. Cardiac output (Q) was measured beat-by-beat using pulsed Doppler ultrasound, and blood pressure was measured beat-by-beat using a non-invasive finger cuff (Finapres). All data were calculated off-line, second-by-second. 3. Arteriovenous oxygen difference (A-VO2) was calculated from Q and VO2 using the Fick Principle. Left ventricular afterload was calculated by dividing Q by mean blood pressure. 4. The data for Q and VO2 were closely fitted by single exponential curves (mean r2 0.84 and 0.90 respectively; r is the correlation coefficient). These curves yielded mean time constants for the increases in Q and VO2 of 28 and 55 s respectively following the increase in exercise level. In each individual subject, the time course of adjustment of Q was faster than that of VO2. There was a mean lag of 15 s from the start of the new exercise level before the derived A-V O2 began to increase; the mean time constant for A-V O2 was 57 s. 5. If A-V O2 had remained constant, the observed rise in Q alone would have resulted in an average of 87% of the increase in VO2 which was observed after 5 s. If Q had remained constant, the observed increase in A-V O2 would have led to only 8% of the actual increase in VO2 after 5 s. 6. Mean and systolic blood pressure rose and afterload fell immediately after the onset of the increased workload. The time constants of the systolic blood pressure and afterload responses to exercise varied widely and ranged from 37 to 81 and 10 to 26 s respectively (n = 4). 7. We conclude that Q is responsible for most of the early increase in VO2

  6. Usefulness of the Diagnosis "Decreased Cardiac Output (00029)" in Patients With Chronic Heart Failure.

    PubMed

    Rojas Sánchez, Lyda Zoraya; Hernández Vargas, Juliana Alexandra; Trujillo Cáceres, Silvia Juliana; Roa Díaz, Zayne Milena; Jurado Arenales, Adriana Milena; Toloza Pérez, Yesith Guillermo

    2016-05-31

    To determine the clinical and construct validity of the nursing diagnosis "decreased cardiac output" (DCO) in patients with chronic heart failure. Cross-sectional study. A total of 200 people were studied. The defining characteristics with the highest prevalence were as follows: arrhythmia (62.5%) and fatigue (61.5%). Adjustment measures such as infit and outfit were maintained between 0.50 and 1.56 and the total variance explained by the measures was 29.3%. This study determined the clinical validity of the nursing diagnosis DCO. Regarding construct validity, adjustment of the defining characteristics to the Rasch model was observed. This study improves the evidence-based practice of nursing and strengthened the role of the nurse who leads care to this population. Determinar la validez clínica y de constructo del diagnóstico de enfermería "Disminución del Gasto Cardíaco" en pacientes con falla cardíaca crónica. MÉTODOS: Estudio de corte transversal. Un total de 200 pacientes fueron estudiados. Las características definitorias con las mayores prevalencias fueron: arritmia (62.5%) y fatiga (61.5%). Medidas de ajuste como el infit y outfit se mantuvieron entre 0.50 y 1.56. El total de la varianza explicada por las medidas fue de 29.3%. Este estudio determinó la validez clínica del diagnóstico de enfermería "Disminución del Gasto Cardíaco". En cuanto a la validez de constructo, se observó que 19 de las 21 características definitorias se ajustaron al modelo Rasch. IMPLICACIONES PARA LA PRÁCTICA DE ENFERMERÍA: Este estudio mejora la práctica basada en la evidencia de enfermería y fortalece el rol de las enfermeras que lideran el cuidado en esta población. © 2016 NANDA International, Inc.

  7. Cardiac output following fetoscopic coagulation of major placental vessels in fetal sheep.

    PubMed

    Tchirikov, M; Strohner, M; Popovic, S; Hecher, K; Schröder, H J

    2008-12-01

    To measure changes in cardiac output (CO) after partial cord occlusion in fetal sheep in order to investigate pathophysiological fetal adaptation mechanisms in a simulated acute placental insufficiency model under standardized conditions, with the aim of finding relevant methods for monitoring human fetuses during stress situations. We used minimally invasive, percutaneous endoscopic techniques to close umbilical vessels in mid-gestational fetal sheep. Placental blood flow was reduced by preferentially closing first arterial and then the concomitant venous umbilical vessels within a short time interval. The investigations were carried out on 11 pregnant ewes at a median gestational age of 86 (range, 73-95) days. Major placental arteries and veins were occluded permanently by coagulation with bipolar forceps under percutaneous fetoscopic control. The fetal CO and Doppler parameters in the ductus venosus (DV), umbilical artery (UA) and umbilical vein (UV) were measured. In spite of heart rate reduction, the CO was not significantly affected by vessel occlusion (mean +/- SD, 500 +/- 194 mL/min before and 457 +/- 219 mL/min after coagulation) because stroke volume slightly increased from 2.65 +/- 1.16 mL/beat to 3.1 +/- 1.5 mL/beat. The right to left CO ratio remained at 1.4. The UV flow/combined CO ratio decreased from 34 +/- 14% to 25 +/- 10% after vessel coagulation. The pulsatility index in the DV increased from 0.4 +/- 0.1 to 0.7 +/- 0.4. The DV blood flow volume remained relatively constant after the intervention. The DV shunting rate, given as DV/UV flow ratio, increased significantly from 30.8 +/- 4.7% to 59.3 +/- 25.0%. The nearly simultaneous closure of arterial and venous umbilical vessels changed the flow pattern in the UA and significantly reduced placental blood perfusion. It did not distinctly change the blood flow volume rate through the DV, and consequently the DV shunting rate was increased. The combined CO was not significantly affected by the

  8. Evaluation of the estimated continuous cardiac output monitoring system in adults and children undergoing kidney transplant surgery: a pilot study.

    PubMed

    Terada, Takashi; Maemura, Yumi; Yoshida, Akiko; Muto, Rika; Ochiai, Ryoichi

    2014-02-01

    Evaluation of the estimated continuous cardiac output (esCCO) allows non-invasive and continuous assessment of cardiac output. However, the applicability of this approach in children has not been assessed thus far. We compared the correlation coefficient, bias, standard deviation (SD), and the lower and upper 95 % limits of agreement for esCCO and dye densitography-cardiac output (DDG-CO) measurements by pulse dye densitometry (PDD) in adults and children. On the basis of these assessments, we aimed to examine whether esCCO can be used in pediatric patients. DDG-CO was measured by pulse dye densitometry (PDD) using indocyanine green. Modified-pulse wave transit time, obtained using pulse oximetry and electrocardiography, was used to measure esCCO. Correlations between DDG-CO and esCCO in adults and children were analyzed using regression analysis with the least squares method. Differences between the two correlation coefficients were statistically analyzed using a correlation coefficient test. Bland-Altman plots were used to evaluate bias and SD for DDG-CO and esCCO in both adults and children, and 95 % limits of agreement (bias ± 1.96 SD) and percentage error (1.96 SD/mean DDG-CO) were calculated and compared. The average age of the adult patients (n = 10) was 39.3 ± 12.1 years, while the average age of the pediatric patients (n = 7) was 9.4 ± 3.1 years (p < 0.001). For adults, the correlation coefficient was 0.756; bias, -0.258 L/min; SD, 1.583 L/min; lower and upper 95 % limits of agreement for DDG-CO and esCCO, -3.360 and 2.844 L/min, respectively; and percentage error, 42.7 %. For children, the corresponding values were 0.904; -0.270; 0.908; -2.051 and 1.510 L/min, respectively; and 35.7 %. Due to the high percentage error values, we could not establish a correlation between esCCO and DDG-CO. However, the 95 % limits of agreement and percentage error were better in children than in adults. Due to the high percentage error, we could not confirm a correlation

  9. PRESAGE 3D dosimetry accurately measures Gamma Knife output factors

    NASA Astrophysics Data System (ADS)

    Klawikowski, Slade J.; Yang, James N.; Adamovics, John; Ibbott, Geoffrey S.

    2014-12-01

    Small-field output factor measurements are traditionally very difficult because of steep dose gradients, loss of lateral electronic equilibrium, and dose volume averaging in finitely sized detectors. Three-dimensional (3D) dosimetry is ideal for measuring small output factors and avoids many of these potential challenges of point and 2D detectors. PRESAGE 3D polymer dosimeters were used to measure the output factors for the 4 mm and 8 mm collimators of the Leksell Perfexion Gamma Knife radiosurgery treatment system. Discrepancies between the planned and measured distance between shot centers were also investigated. A Gamma Knife head frame was mounted onto an anthropomorphic head phantom. Special inserts were machined to hold 60 mm diameter, 70 mm tall cylindrical PRESAGE dosimeters. The phantom was irradiated with one 16 mm shot and either one 4 mm or one 8 mm shot, to a prescribed dose of either 3 Gy or 4 Gy to the 50% isodose line. The two shots were spaced between 30 mm and 60 mm apart and aligned along the central axis of the cylinder. The Presage dosimeters were measured using the DMOS-RPC optical CT scanning system. Five independent 4 mm output factor measurements fell within 2% of the manufacturer’s Monte Carlo simulation-derived nominal value, as did two independent 8 mm output factor measurements. The measured distances between shot centers varied by ±0.8 mm with respect to the planned shot displacements. On the basis of these results, we conclude that PRESAGE dosimetry is excellently suited to quantify the difficult-to-measure Gamma Knife output factors.

  10. Beta-adrenergic or parasympathetic inhibition, heart rate and cardiac output during normoxic and acute hypoxic exercise in humans.

    PubMed

    Hopkins, Susan R; Bogaard, Harm J; Niizeki, Kyuichi; Yamaya, Yoshiki; Ziegler, Michael G; Wagner, Peter D

    2003-07-15

    Acute hypoxia increases heart rate (HR) and cardiac output (Qt) at a given oxygen consumption (VO2) during submaximal exercise. It is widely believed that the underlying mechanism involves increased sympathetic activation and circulating catecholamines acting on cardiac beta receptors. Recent evidence indicating a continued role for parasympathetic modulation of HR during moderate exercise suggests that increased parasympathetic withdrawal plays a part in the increase in HR and Qt during hypoxic exercise. To test this, we separately blocked the beta-sympathetic and parasympathetic arms of the autonomic nervous system (ANS) in six healthy subjects (five male, one female; mean +/- S.E.M. age = 31.7+/-1.6 years, normoxic maximal VO2 (VO2,max)=3.1+/-0.3 l min(-1)) during exercise in conditions of normoxia and acute hypoxia (inspired oxygen fraction=0.125) to VO2,max. Data were collected on different days under the following conditions: (1)control, (2) after 8.0 mg propranolol i.v. and (3) after 0.8 mg glycopyrrolate i.v. Qt was measured using open-circuit acetylene uptake. Hypoxia increased venous [adrenaline] and [noradrenaline] but not [dopamine] at a given VO2 (P<0.05, P<0.01 and P=0.2, respectively). HR/VO2 and Qt/VO2 increased during hypoxia in all three conditions (P<0.05). Unexpectedly, the effects of hypoxia on HR and Qt were not significantly different from control with either beta-sympathetic or parasympathetic inhibition. These data suggest that although acute exposure to hypoxia increases circulating [catecholamines], the effects of hypoxia on HR and Qt do not necessarily require intact cardiac muscarinic and beta receptors. It may be that cardiac alpha receptors play a primary role in elevating HR and Qt during hypoxic exercise, or perhaps offer an alternative mechanism when other ANS pathways are blocked.

  11. Differential acute effects of carbohydrate- and protein-rich drinks compared with water on cardiac output during rest and exercise in healthy young men.

    PubMed

    Rontoyanni, Victoria G; Werner, Kristin; Sanders, Thomas A B; Hall, Wendy L

    2015-08-01

    The acute effects of drinks rich in protein (PRO) versus carbohydrate (CHO) on cardiovascular hemodynamics and reactivity are uncertain. A randomized crossover design was used to compare 400-mL isoenergetic (1.1 MJ) drinks containing whey protein (PRO; 44 g) or carbohydrate (CHO; 57 g) versus 400 mL of water in 14 healthy men. The primary and secondary outcomes were changes in cardiac output, blood pressure, systemic vascular resistance (SVR) and digital volume pulse measured prior to and 30 min following consumption at rest, during 12 min of multi-stage bicycle ergometry, and 15 min postexercise. The mean change (95% confidence interval (CI)) in resting cardiac output at 30 min was greater for CHO than for PRO or water: 0.7 (0.4 to 1.0), 0.1 (-0.2 to 0.40), and 0.0 (-0.3 to 0.3) L/min (P < 0.001), respectively; the higher cardiac output following CHO was accompanied by an increase in stroke volume and a lower SVR. The mean increments (95% CI) in cardiac output during exercise were CHO 4.7 (4.4 to 5.0), PRO 4.9 (4.6 to 5.2), and water 4.6 (4.3 to 4.9) L/min with the difference between PRO versus water being significant (P < 0.025). There were no other statistically significant differences. In summary, a CHO-rich drink increased cardiac output and lowered SVR in the resting state compared with a PRO-rich drink or water but the effect size of changes in these variables did not differ during or after exercise between CHO and PRO. Neither protein nor carbohydrate affected blood pressure reactivity to exercise.

  12. Endurance training and maximal oxygen consumption with ageing: Role of maximal cardiac output and oxygen extraction.

    PubMed

    Montero, David; Díaz-Cañestro, Candela

    2016-05-01

    The increase in maximal oxygen consumption (VO2max) with endurance training is associated with that of maximal cardiac output (Qmax), but not oxygen extraction, in young individuals. Whether such a relationship is altered with ageing remains unclear. Therefore, we sought systematically to review and determine the effect of endurance training on and the associations among VO2max, Qmax and arteriovenous oxygen difference at maximal exercise (Ca-vO2max) in healthy aged individuals. We conducted a systematic search of MEDLINE, Scopus and Web of Science, from their inceptions until May 2015 for articles assessing the effect of endurance training lasting 3 weeks or longer on VO2max and Qmax and/or Ca-vO2max in healthy middle-aged and/or older individuals (mean age ≥40 years). Meta-analyses were performed to determine the standardised mean difference (SMD) in VO2max, Qmax and Ca-vO2max between post and pre-training measurements. Subgroup and meta-regression analyses were used to evaluate the associations among SMDs and potential moderating factors. Sixteen studies were included after systematic review, comprising a total of 153 primarily untrained healthy middle-aged and older subjects (mean age 42-71 years). Endurance training programmes ranged from 8 to 52 weeks of duration. After data pooling, VO2max (SMD 0.89; P < 0.0001) and Qmax (SMD 0.61; P < 0.0001) were increased after endurance training; no heterogeneity among studies was detected. Ca-vO2max was only increased with endurance training interventions lasting more than 12 weeks (SMD 0.62; P = 0.001). In meta-regression, the SMD in Qmax was positively associated with the SMD in VO2max (B = 0.79, P = 0.04). The SMD in Ca-vO2max was not associated with the SMD in VO2max (B = 0.09, P = 0.84). The improvement in VO2max following endurance training is a linear function of Qmax, but not Ca-vO2max, through healthy ageing. © The European Society of Cardiology 2015.

  13. Transthoracic echocardiography: an accurate and precise method for estimating cardiac output in the critically ill patient.

    PubMed

    Mercado, Pablo; Maizel, Julien; Beyls, Christophe; Titeca-Beauport, Dimitri; Joris, Magalie; Kontar, Loay; Riviere, Antoine; Bonef, Olivier; Soupison, Thierry; Tribouilloy, Christophe; de Cagny, Bertrand; Slama, Michel

    2017-06-09

    Cardiac output (CO) monitoring is a valuable tool for the diagnosis and management of critically ill patients. In the critical care setting, few studies have evaluated the level of agreement between CO estimated by transthoracic echocardiography (CO-TTE) and that measured by the reference method, pulmonary artery catheter (CO-PAC). The objective of the present study was to evaluate the precision and accuracy of CO-TTE relative to CO-PAC and the ability of transthoracic echocardiography to track variations in CO, in critically ill mechanically ventilated patients. Thirty-eight mechanically ventilated patients fitted with a PAC were included in a prospective observational study performed in a 16-bed university hospital ICU. CO-PAC was measured via intermittent thermodilution. Simultaneously, a second investigator used standard-view TTE to estimate CO-TTE as the product of stroke volume and the heart rate obtained during the measurement of the subaortic velocity time integral. Sixty-four pairs of CO-PAC and CO-TTE measurements were compared. The two measurements were significantly correlated (r = 0.95; p < 0.0001). The median bias was 0.2 L/min, the limits of agreement (LOAs) were -1.3 and 1.8 L/min, and the percentage error was 25%. The precision was 8% for CO-PAC and 9% for CO-TTE. Twenty-six pairs of ΔCO measurements were compared. There was a significant correlation between ΔCO-PAC and ΔCO-TTE (r = 0.92; p < 0.0001). The median bias was -0.1 L/min and the LOAs were -1.3 and +1.2 L/min. With a 15% exclusion zone, the four-quadrant plot had a concordance rate of 94%. With a 0.5 L/min exclusion zone, the polar plot had a mean polar angle of 1.0° and a percentage error LOAs of -26.8 to 28.8°. The concordance rate was 100% between 30 and -30°. When using CO-TTE to detect an increase in ΔCO-PAC of more than 10%, the area under the receiving operating characteristic curve (95% CI) was 0.82 (0.62-0.94) (p < 0.001). A ΔCO-TTE of more than 8

  14. Low Cardiac Output Secondary to a Malpositioned Umbilical Venous Catheter: Value of Targeted Neonatal Echocardiography

    PubMed Central

    Weisz, Dany E.; Poon, Wei Bing; James, Andrew; McNamara, Patrick J.

    2014-01-01

    Systemic hypotension is common in very low birthweight preterm infants but the nature of the precipitating cause may be unclear. Targeted neonatal echocardiography (TnEcho) is being increasingly used to support hemodynamic decisions in the neonatal intensive care unit (NICU), including identifying impairments in the transitional circulation of preterm infants, providing timely re-evaluation after institution of therapies and evaluating the placement of indwelling catheters. We present a case of a preterm infant with systemic hypotension and low cardiac output secondary to a large transatrial shunt induced by a malpositioned umbilical venous catheter. Repositioning of the line led to resolution of the hemodynamic disturbance and clinical instability, highlighting the utility of TnEcho in the NICU. PMID:25032055

  15. Monitoring Cardiac Output and Transesophageal Echocardiography during Removal of a Ventricular Assist Device.

    PubMed

    Demir, Aslı; Karadeniz, Ümit; Aydınlı, Bahar; Taş, Murat; Erdemli, Özcan

    2013-12-01

    A ventricular assist device (VAD) is a mechanical pump used to support heart function and blood flow in patients with poor heart functions. For selected patients who are too ill to wait for a heart transplant or are not eligible for a heart transplant because of age or other medical problems, ventricular assist devices offer life-saving therapy. This device has also become a life-saving approach for patients with acute viral myocarditis. Following the acute illness phase, when heart function has improved, the VAD is carefully removed. It is very important to continuously monitor myocardial functions during this period. In this paper, we present a patient who underwent cardiac output and transesophageal echocardiography monitoring during VAD removal.

  16. Monitoring Cardiac Output and Transesophageal Echocardiography during Removal of a Ventricular Assist Device

    PubMed Central

    Demir, Aslı; Karadeniz, Ümit; Aydınlı, Bahar; Taş, Murat; Erdemli, Özcan

    2013-01-01

    A ventricular assist device (VAD) is a mechanical pump used to support heart function and blood flow in patients with poor heart functions. For selected patients who are too ill to wait for a heart transplant or are not eligible for a heart transplant because of age or other medical problems, ventricular assist devices offer life-saving therapy. This device has also become a life-saving approach for patients with acute viral myocarditis. Following the acute illness phase, when heart function has improved, the VAD is carefully removed. It is very important to continuously monitor myocardial functions during this period. In this paper, we present a patient who underwent cardiac output and transesophageal echocardiography monitoring during VAD removal. PMID:27366376

  17. Meaningful outcome measures in cardiac surgery.

    PubMed

    Myles, Paul S

    2014-03-01

    The most common cardiac surgical procedures are coronary artery bypass graft surgery and aortic or mitral valve repair or replacement. Underlying conditions include coronary artery disease and heart failure, manifesting as exertional angina, dyspnea, and poor exercise tolerance. The major goals of surgery are to alleviate symptoms and improve patient survival. These, therefore, should inform the choice of primary outcome measures in clinical studies enrolling patients undergoing cardiac surgery. Studies focusing on surrogate outcome measures are relied on all too often. Many are of questionable significance and often have no convincing relationship with patient outcome. Traditional "hard endpoint" outcome measures include serious complications and death with the former including myocardial infarction (MI) and stroke. Such serious adverse outcomes are commonly collected in registries, but because they occur infrequently, they need to be large to reliably detect true associations and treatment effects. For this reason, some investigators combine several outcomes into a single composite endpoint. Cardiovascular trials commonly use major adverse cardiac events (MACEs) as a composite primary endpoint. However, there is no standard definition for MACE. Most include MI, stroke, and death; others include rehospitalization for heart failure, revascularization, cardiac arrest, or bleeding complications. An influential trial in noncardiac surgery found that perioperative beta-blockers reduced the risk of MI but increased the risk of stroke and death. Such conflicting findings challenge the veracity of such composite endpoints and raise a far more important question: which of these endpoints, or even others that were unmeasured, are most important to a patient recovering from surgery? Given the primary aims of cardiac surgery are to relieve symptoms and improve good quality survival, it is disability-free survival that is the ultimate outcome measure. The question then becomes

  18. Gamma Knife output factor measurements using VIP polymer gel dosimetry

    SciTech Connect

    Moutsatsos, A.; Petrokokkinos, L.; Karaiskos, P.; Papagiannis, P.; Georgiou, E.; Dardoufas, K.; Sandilos, P.; Torrens, M.; Pantelis, E.; Kantemiris, I.; Sakelliou, L.; Seimenis, I.

    2009-09-15

    Purpose: Water equivalent polymer gel dosimeters and magnetic resonance imaging were employed to measure the output factors of the two smallest treatment fields available in a Gamma Knife model C radiosurgery unit, those formed employing the 4 and 8 mm final collimator helmets. Methods: Three samples of the VIP normoxic gel formulation were prepared and irradiated so that a single shot of the field whose output factor is to be measured and a single shot of the reference 18 mm field were delivered in each one. Emphasis is given to the development and benchmarking of a refined data processing methodology of reduced uncertainty that fully exploits the 3D dose distributions registered in the dosimeters. Results: Polymer gel results for the output factor of the 8 mm collimator helmet are found to be in close agreement with the corresponding value recommended by the vendor (0.955{+-}0.007 versus 0.956, respectively). For the 4 mm collimator helmet, however, polymer gel results suggest an output factor 3% lower than the value recommended by the vendor (0.841{+-}0.009 versus 0.870, respectively). Conclusions: A comparison with corresponding measurements published in the literature indicates that output factor results of this work are in agreement with those obtained using dosimetric systems which, besides fine spatial resolution and lack of angular and dose rate dependence of the dosimeter's response, share with polymer gels the favorable characteristic of minimal radiation field perturbation.

  19. Continuous positive pressure ventilation during epidural blockade--effects on cardiac output distribution.

    PubMed

    Elowsson, P; Norlén, K; Jakobson, S

    2001-01-01

    It has been shown that when cardiac output (CO) decreases during continuous positive pressure ventilation (CPPV), its regional distribution adapts with a favouring of vital organs. Does epidural blockade modify this adaptation? Regional blood flows were assessed by the microsphere technique (15 microm) in 17 anaesthetised pigs during spontaneous breathing and CPPV with 8 cm H2O end-expiratory pressure (CPPV8) before and after epidural blockade. The block was induced at either the Th6-7 (Thep) or the L6-S1 (Lep) level with 1 ml of lidocaine 40 mg x ml(-1). When Lep was combined with CPPV8, mean arterial pressure and CO decreased significantly, and they decreased even more when combined with Thep. In contrast, the relative perfusion of the central nervous system, heart and kidneys remained stable during the four conditions studied. The adrenal perfusion during CPPV8 was obviated by epidural blockade. The absolute and relative perfusion of the skeletal muscle decreased during epidural blockade. The administered doses of epidural lidocaine did not affect blood flow in the spinal cord. The locally mediated nutritive vasoregulation of vital organs outweighed the sympathetic blockade induced by epidural blockade. During Thep blockade the animals were less capable of responding to the haemodynamic changes induced by CPPV8, probably due to the blockade of the cardiac part of the sympathetic nervous system.

  20. Noninvasive aortic bloodflow by Pulsed Doppler Echocardiography (PDE) compared to cardiac output by the direct Fick procedure

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Left ventricular stroke volume was estimated from the systolic velocity integral in the ascending aorta by pulsed Doppler Echocardiography (PDE) and the cross sectional area of the aorta estimated by M mode echocardiography on 15 patients with coronary disease undergoing right catheterization for diagnostic purposes. Cardiac output was calculated from stroke volume and heart volume using the PDE method as well as the Fick procedure for comparison. The mean value for the cardiac output via the PDE method (4.42 L/min) was only 6% lower than for the cardiac output obtained from the Fick procedure (4.69 L/min) and the correlation between the two methods was excellent (r=0.967, p less than .01). The good agreement between the two methods demonstrates that the PDE technique offers a reliable noninvasive alternative for estimating cardiac output, requiring no active cooperation by the subject. It was concluded that the Doppler method is superior to the Fick method in that it provides beat by beat information on cardiac performance.

  1. The Neuromuscular Transform of the Lobster Cardiac System Explains the Opposing Effects of a Neuromodulator on Muscle Output

    PubMed Central

    Williams, Alex H.; Calkins, Andrew; O'Leary, Timothy; Symonds, Renee; Marder, Eve

    2013-01-01

    Motor neuron activity is transformed into muscle movement through a cascade of complex molecular and biomechanical events. This nonlinear mapping of neural inputs to motor behaviors is called the neuromuscular transform (NMT). We examined the NMT in the cardiac system of the lobster Homarus americanus by stimulating a cardiac motor nerve with rhythmic bursts of action potentials and measuring muscle movements in response to different stimulation patterns. The NMT was similar across preparations, which suggested that it could be used to predict muscle movement from spontaneous neural activity in the intact heart. We assessed this possibility across semi-intact heart preparations in two separate analyses. First, we performed a linear regression analysis across 122 preparations in physiological saline to predict muscle movements from neural activity. Under these conditions, the NMT was predictive of contraction duty cycle but was unable to predict contraction amplitude, likely as a result of uncontrolled interanimal variability. Second, we assessed the ability of the NMT to predict changes in motor output induced by the neuropeptide C-type allatostatin. Wiwatpanit et al. (2012) showed that bath application of C-type allatostatin produced either increases or decreases in the amplitude of the lobster heart contractions. We show that an important component of these preparation-dependent effects can arise from quantifiable differences in the basal state of each preparation and the nonlinear form of the NMT. These results illustrate how properly characterizing the relationships between neural activity and measurable physiological outputs can provide insight into seemingly idiosyncratic effects of neuromodulators across individuals. PMID:24133260

  2. The Output of Canadian Universities as Measured by Graduate Degrees.

    ERIC Educational Resources Information Center

    Farine, Avigdor

    This paper presents the results of a study of the output of Canadian universities as measured by graduate degrees conferred or by graduates produced. The study was conducted to answer 2 basic questions: (1) Do Quebec universities train enough qualified manpower in comparison with the other provinces? and (2) Encouraged by funds and by the Quebec…

  3. Real-ear output measures of ear level fluency devices.

    PubMed

    Stuart, Andrew; Butler, Alyson K; Jones, Sherri M; Jones, Timothy A

    2013-06-01

    The purpose of this study was to measure real-ear aided and saturated responses of SpeechEasy™ devices and compare responses while devices delivered altered auditory feedback (AAF) and non-altered feedback (NAF). A repeated measures quasi-experimental design was employed. Ten people fitted with completely-in-the-canal or open fit behind-the-ear devices participated. Probe microphone measures were obtained with speech, and 17 chirp stimuli presented at 75 dB and 85 dB SPL, respectively. Measurements were compared with devices delivering AAF (i.e. delayed and frequency shifted) versus NAF. Maximum outputs were approximately 100-105 dB SPL in the 2000-4000 Hz range. Statistically significant differences in device SPL output as a function of device setting (AAF vs. NAF) were found for seven chirp stimuli (p <.05) when levels were sampled at points that were not temporally aligned with the output chirps but not for speech stimulus (p = .17). Device output varied across individuals and with open fit devices dominated by ear canal resonance effects. Real-ear aided responses were equivalent with speech input when devices delivered AAF and NAF. Real-ear saturated responses were not, however, comparable between AAF and NAF settings and may be underestimated if AAF delay is not accounted for.

  4. Oral Consumption of Vitamin K2 for 8 Weeks Associated With Increased Maximal Cardiac Output During Exercise.

    PubMed

    McFarlin, Brian K; Henning, Andrea L; Venable, Adam S

    2017-07-01

    Background • Vitamin K1 and K2 are not typically common in a Western diet because they are found in a variety of fermented foods. Vitamin K2 in particular has been demonstrated to restore mitochondrial function and has a key role in production of mitochondrial adenosine triphosphate. Thus, it is reasonable to speculate that dietary supplementation with vitamin K2 could increase the function of muscle with high mitochondrial content (ie, skeletal and cardiac muscle). Objective • The purpose of this study was to determine if 8 wk of dietary supplementation with Vitamin K2 could alter cardiovascular responses to a graded cycle ergometer test. Design • The study was a randomized controlled trial. Setting • The study took place in the Applied Physiology Laboratory of the Department of Biological Sciences at the University of North Texas (Denton, TX, USA). Participants • Participants were aerobically trained males and female athletes (N = 26). Intervention • Participants were randomly assigned either to a control group that received a rice flour placebo or to an intervention group that received vitamin K2. For weeks 1 to 4, participants received 300 mg/d; for weeks 5 to 8, they received 150 mg/d. Subjects assigned to the control group received similar doses to mirror the intervention group. Subjects consumed the supplements during an 8-wk period while they maintained their typical exercise habits. Outcome Measures • At baseline and postintervention, participants completed a standard, graded exercise test on an electronically braked cycle ergometer. Before the test, participants were fitted with a mouth piece, and their oxygen consumption, carbon dioxide production, respiratory rate, and respiratory exchange ratio were measured. In addition, participants were fitted with skin-mounted electrodes that measured noninvasive cardiac output, stroke volume, and heart rate. To assess the cumulative exercise change, an area-under-the-curve (AUC) value was calculated

  5. Influence of heart motion on cardiac output estimation by means of electrical impedance tomography: a case study.

    PubMed

    Proença, Martin; Braun, Fabian; Rapin, Michael; Solà, Josep; Adler, Andy; Grychtol, Bartłomiej; Bohm, Stephan H; Lemay, Mathieu; Thiran, Jean-Philippe

    2015-06-01

    Electrical impedance tomography (EIT) is a non-invasive imaging technique that can measure cardiac-related intra-thoracic impedance changes. EIT-based cardiac output estimation relies on the assumption that the amplitude of the impedance change in the ventricular region is representative of stroke volume (SV). However, other factors such as heart motion can significantly affect this ventricular impedance change. In the present case study, a magnetic resonance imaging-based dynamic bio-impedance model fitting the morphology of a single male subject was built. Simulations were performed to evaluate the contribution of heart motion and its influence on EIT-based SV estimation. Myocardial deformation was found to be the main contributor to the ventricular impedance change (56%). However, motion-induced impedance changes showed a strong correlation (r = 0.978) with left ventricular volume. We explained this by the quasi-incompressibility of blood and myocardium. As a result, EIT achieved excellent accuracy in estimating a wide range of simulated SV values (error distribution of 0.57 ± 2.19 ml (1.02 ± 2.62%) and correlation of r = 0.996 after a two-point calibration was applied to convert impedance values to millilitres). As the model was based on one single subject, the strong correlation found between motion-induced changes and ventricular volume remains to be verified in larger datasets.

  6. Clinical significance of a spiral phenomenon in the plot of CO₂ output versus O₂ uptake during exercise in cardiac patients.

    PubMed

    Nagayama, Osamu; Koike, Akira; Himi, Tomoko; Sakurada, Koji; Kato, Yuko; Suzuki, Shinya; Sato, Akira; Yamashita, Takeshi; Wasserman, Karlman; Aonuma, Kazutaka

    2015-03-01

    A spiral phenomenon is sometimes noted in the plots of CO₂ output (VCO₂) against O₂ uptake (VO₂) measured during cardiopulmonary exercise testing (CPX) in patients with heart failure with oscillatory breathing. However, few data are available that elucidate the clinical significance of this phenomenon. Our group studied the prevalence of this phenomenon and its relation to cardiac and cardiopulmonary function. Of 2,263 cardiac patients who underwent CPX, 126 patients with a clear pattern of oscillatory breathing were identified. Cardiopulmonary indexes were compared between patients who showed the spiral phenomenon (n = 49) and those who did not (n = 77). The amplitudes of VO₂ and VCO₂ oscillations were greater and the phase difference between VO₂ and VCO₂ oscillations was longer in the patients with the spiral phenomenon than in those without it. Patients with the spiral phenomenon also had a lower left ventricular ejection fraction (43.4 ± 21.4% vs 57.1 ± 16.8%, p <0.001) and a higher level of brain natriuretic peptide (637.2 ± 698.3 vs 228.3 ± 351.4 pg/ml, p = 0.002). The peak VO₂ was lower (14.5 ± 5.6 vs 18.1 ± 6.3, p = 0.002), the slope of the increase in ventilation versus VCO₂ was higher (39.8 ± 9.5 vs 33.6 ± 6.8, p <0.001), and end-tidal PCO₂ both at rest and at peak exercise was lower in the patients with the spiral phenomenon than in those without it. In conclusion, the spiral phenomenon in the VCO₂-versus-VO₂ plot arising from the phase difference between VCO₂ and VO₂ oscillations reflects more advanced cardiopulmonary dysfunction in cardiac patients with oscillatory breathing.

  7. The Higher the Insulin Resistance the Lower the Cardiac Output in Men with Type 1 Diabetes During the Maximal Exercise Test.

    PubMed

    Niedzwiecki, Pawel; Naskret, Dariusz; Pilacinski, Stanislaw; Pempera, Maciej; Uruska, Aleksandra; Adamska, Anna; Zozulinska-Ziolkiewicz, Dorota

    2017-06-01

    The aim of this study was to assess the hemodynamic parameters analyzed in bioimpedance cardiography during maximal exercise in patients with type 1 diabetes differing in insulin resistance. The study group consisted of 40 men with type 1 diabetes. Tissue sensitivity to insulin was assessed on the basis of the glucose disposal rate (GDR) analyzed during hyperinsulinemic-euglycemic clamp. Patients were divided into groups with GDR <4.5 mg/kg/min (G1 group-lower insulin sensitivity) and GDR ≥4.5 mg/kg/min (G2 group-higher insulin sensitivity). During the exercise test, the heart rate, systolic volume, cardiac output, cardiac index were measured by the impedance meter (PhysioFlow). Compared with the G2 group, the G1 group had a lower cardiac output (CO): during exercise 8.6 (IQR 7.7-10.0) versus 12.8 (IQR 10.8-13.7) L/min; P < 0.0001, at the maximal effort 13.1 (IQR 12.2-16.7) versus 18.6 (IQR 16.9-20.2) L/min; P = 0.001, and during observation after exercise 8.4 (IQR 6.3-9.6) versus 11.9 (IQR 10.1-13.1) L/min; P < 0.0001. We noticed a positive correlation of GDR and cardiac output: during the exercise test (r = 0.63, P = 0.0002), at the maximal effort (Rs 0.56, P = 0.001), and during observation after the exercise test (r = 0.72, P < 0.0001). In multivariate logistic regression, cardiac output during exercise and during observation was associated with high GDR, regardless of the age and duration of diabetes [OR: 1.98 (95% CI 1.10-3.56), P = 0.02 and OR: 1.91 (95% CI 1.05-3.48), P = 0.03; respectively]. In nonobese subjects with type 1 diabetes, with good metabolic control, insulin resistance is associated with cardiac hemodynamic parameters assessed during and after exercise. The higher the insulin resistance the lower the cardiac output during maximal exercise in men with type 1 diabetes.

  8. Heat flow calorimeter. [measures output of Ni-Cd batteries

    NASA Technical Reports Server (NTRS)

    Fletcher, J. C.; Johnston, W. V. (Inventor)

    1974-01-01

    Heat flow calorimeter devices are used to measure heat liberated from or absorbed by an object. This device is capable of measuring the thermal output of sealed nickel-cadmium batteries or cells during charge-discharge cycles. An elongated metal heat conducting rod is coupled between the calorimeter vessel and a heat sink, thus providing the only heat exchange path from the calorimeter vessel itself.

  9. Can stroke volume and cardiac output be determined reliably in a tilt-table test using the pulse contour method?

    PubMed

    Nieminen, T; Kööbi, T; Turjanmaa, V

    2000-11-01

    The applicability of the finger pressure-derived pulse contour (PC) technique was evaluated in the measurement of stroke volume (SV), cardiac output (CO) and their changes in different phases of the tilt-table test. The reference method was whole-body impedance cardiography (ICG). A total number of 40 physically active patients, aged 41 +/- 19 years, were randomly chosen from a pool of 230. Specifically speaking, 20 of the patients experienced (pre)syncope (tilt+ patients) during the head-up tilt (HUT), and 20 did not (tilt-). A total number of three measurement periods, 30-60 s each, were analysed: supine position, 5 min after the commencement of HUT, and 1 min before set down. SV and CO values measured by PC underestimated significantly those measured by ICG (biases +/- SD 19 +/- 14 ml and 1.55 +/- 1.14 l min-1, respectively) in agreement with earlier reports. The bias between the methods was almost the same in the different phases of the test. However, the SD of the bias was bigger for tilt+ (P < 0.05). When the bias between the methods was eliminated by scaling the first measurement to 100%, the agreement between the methods in the second and third measurements was clearly better than without scaling. Both methods showed a physiological drop in SV after the commencement of HUT. These results indicate that PC suffices in tracking the changes in CO and SV, but for absolute values it is not reliable.

  10. Acoustic output of multi-line transmit beamforming for fast cardiac imaging: a simulation study.

    PubMed

    Santos, Pedro; Tong, Ling; Ortega, Alejandra; Løvstakken, Lasse; Samset, Eigil; D'hooge, Jan

    2015-07-01

    Achieving higher frame rates in cardiac ultrasound could unveil short-lived myocardial events and lead to new insights on cardiac function. Multi-line transmit (MLT) beamforming (i.e., simultaneously transmitting multiple focused beams) is a potential approach to achieve this. However, two challenges come with it: first, it leads to cross-talk between the MLT beams, appearing as imaging artifacts, and second, it presents acoustic summation in the near field, where multiple MLT beams overlap. Although several studies have focused on the former, no studies have looked into the implications of the latter on acoustic safety. In this paper, the acoustic field of 4-MLT was simulated and compared with single-line transmit (SLT). The findings suggest that standard MLT does present potential concerns. Compared with SLT, it shows a 2-fold increase in mechanical index (MI) (from 1.0 to 2.3), a 6-fold increase in spatial-peak pulse-average intensity (I(sppa)) (from 99 to 576 W∙cm(-2)) and a 12-fold increase in spatial-peak temporalaverage intensity (I(spta)) (from 119 to 1407 mW∙cm(-2)). Subsequently, modifications of the transmit pulse and delay line of MLT were studied. These modifications allowed for a change in the spatio-temporal distribution of the acoustic output, thereby significantly decreasing the safety indices (MI = 1.2, I(sppa) = 92 W∙cm(-2) and I(spta) = 366 mW∙cm(-2)). Accordingly, they help mitigate the concerns around MLT, reducing potential tradeoffs between acoustic safety and image quality.

  11. Early predictors of acute kidney injury in patients with cirrhosis and bacterial infection: urinary neutrophil gelatinase-associated lipocalin and cardiac output as reliable tools

    PubMed Central

    Ximenes, Rafael O.; Farias, Alberto Q.; Helou, Claudia M.B.

    2015-01-01

    Background Hemodynamic abnormalities and acute kidney injury (AKI) are often present in infected cirrhotic patients. Hence, an early diagnosis of AKI is necessary, which might require the validation of new predictors as the determinations of urinary neutrophil gelatinase-associated lipocalin (uNGAL) and cardiac output. Methods We evaluated 18 infected cirrhotic patients subdivided into two groups at admission (0 hours). In Group I, we collected urine samples at 0 hours, 6 hours, 24 hours, and 48 hours for uNGAL and fractional excretion of sodium determinations. In Group II, we measured cardiac output using echocardiography. Results The age of patients was 55.0±1.9 years, and 11 patients were males. The Model for End-Stage Liver Disease score was 21±1, whereas the Child–Pugh score was C in 11 patients and B in 7 patients. Both patients in Group I and Group II showed similar baseline characteristics. In Group I, we diagnosed AKI in 5 of 9 patients, and the mean time to this diagnosis by measuring serum creatinine was 5.4 days. Patients with AKI showed higher uNGAL levels than those without AKI from 6 hours to 48 hours. The best accuracy using the cutoff values of 68 ng uNGAL/mg creatinine was achieved at 48 hours when we distinguished patients with and without AKI in all cases. In Group II, we diagnosed AKI in 4 of 9 patients, and cardiac output was significantly higher in patients who developed AKI at 0 hours. Conclusion Both uNGAL and cardiac output determinations allow the prediction of AKI in infected cirrhotic patients earlier than increments in serum creatinine. PMID:26484038

  12. Femoral Blood Flow and Cardiac Output During Blood Flow Restricted Leg Press Exercise

    NASA Technical Reports Server (NTRS)

    Everett, M. E.; Hackney, K.; Ploutz-Snyder, L.

    2011-01-01

    Low load blood flow restricted resistance exercise (LBFR) causes muscle hypertrophy that may be stimulated by the local ischemic environment created by the cuff pressure. However, local blood flow (BF) during such exercise is not well understood. PURPOSE: To characterize femoral artery BF and cardiac output (CO) during leg press exercise (LP) performed at a high load (HL) and low load (LL) with different levels of cuff pressure. METHODS: Eleven subjects (men/women 4/7, age 31.4+/-12.8 y, weight 68.9+/-13.2 kg, mean+/-SD) performed 3 sets of supine left LP to fatigue with 90 s of rest in 4 conditions: HL (%1-RM/cuff pressure: 80%/0); LL (20%/0); LBFR(sub DBP) (20%/1.3 x diastolic blood pressure, BP); LBFR(sub SBP) (20%/1.3 x supine systolic BP). The cuff remained inflated throughout the LBFR exercise sessions. Artery diameter, velocity time integral (VTI), and stroke volume (SV) were measured using Doppler ultrasound at rest and immediately after each set of exercise. Heart rate (HR) was monitored using a 3-lead ECG. BF was calculated as VTI x vessel cross-sectional area. CO was calculated as HR x SV. The data obtained after each set of exercise were averaged and used for analyses. Multi-level modeling was used to determine the effect of exercise condition on dependent variables. Statistical significance was set a priori at p< 0.05. RESULTS: Artery diameter did not change from baseline. BF increased (p<0.05) after exercise in each condition except LBFR(sub SBP) in the order of HL (12.73+/-1.42 cm3,mean+/-SE) > LL (9.92+/-0.82 cm3) > LBFR(sub dBP)(6.47+/-0.79 cm3) > LBFR(sub SBP) (3.51+/-0.59 cm3). Blunted exercise induced increases occurred in HR, SV, and CO after LBFR compared to HL and LL. HR increased 45% after HL and LL and 28% after LBFR (p<0.05), but SV increased (p<0.05) only after HL. Consequently, the increase (p<0.05) in CO was greater in HL and LL (approximately 3 L/min) than in LBFR (approximately 1 L/min). CONCLUSION: BF during LBFR(sub SBP) was 1/3 of

  13. Left ventricular atrioventricular plane displacement is preserved with lifelong endurance training and is the main determinant of maximal cardiac output.

    PubMed

    Steding-Ehrenborg, Katarina; Boushel, Robert C; Calbet, José A; Åkeson, Per; Mortensen, Stefan P

    2015-12-01

    Age-related decline in cardiac function can be prevented or postponed by lifelong endurance training. However, effects of normal ageing as well as of lifelong endurance exercise on longitudinal and radial contribution to stroke volume are unknown. The aim of this study was to determine resting longitudinal and radial pumping in elderly athletes, sedentary elderly and young sedentary subjects. Furthermore, we aimed to investigate determinants of maximal cardiac output in elderly. Eight elderly athletes (63 ± 4 years), seven elderly sedentary (66 ± 4 years) and ten young sedentary subjects (29 ± 4 years) underwent cardiac magnetic resonance imaging. All subjects underwent maximal exercise testing and for elderly subjects maximal cardiac output during cycling was determined using a dye dilution technique. Longitudinal and radial contribution to stroke volume did not differ between groups (longitudinal left ventricle (LV) 52-65%, P = 0.12, right ventricle (RV) 77-87%, P = 0.16, radial 7.9-8.6%, P = 1.0). Left ventricular atrioventricular plane displacement (LVAVPD) was higher in elderly athletes and young sedentary compared with elderly sedentary subjects (14 ± 3, 15 ± 2 and 11 ± 1 mm, respectively, P < 0.05). There was no difference between groups for RVAVPD (P = 0.2). LVAVPD was an independent predictor of maximal cardiac output (R(2) = 0.61, P < 0.01, β = 0.78). Longitudinal and radial contributions to stroke volume did not differ between groups. However, how longitudinal pumping was achieved differed; elderly athletes and young sedentary subjects showed similar AVPD whereas this was significantly lower in elderly sedentary subjects. Elderly sedentary subjects achieved longitudinal pumping through increased short-axis area of the ventricle. Large AVPD was a determinant of maximal cardiac output and exercise capacity.

  14. Cardiac output but not stroke volume is similar in a Wingate and VO2peak test in young men.

    PubMed

    Fontana, Piero; Betschon, Katharina; Boutellier, Urs; Toigo, Marco

    2011-01-01

    Wingate test (WT) training programmes lasting 2-3 weeks lead to improved peak oxygen consumption. If a single 30 s WT was capable of significantly increasing stroke volume and cardiac output, the increase in peak oxygen consumption could possibly be explained by improved oxygen delivery. Thus, we investigated whether a single WT increases stroke volume and cardiac output to similar levels than those obtained at peak exercise during a graded cycling exercise test (GXT) to exhaustion. Fifteen healthy young men (peak oxygen consumption 45.0 ± 5.3 ml kg(-1) min(-1)) performed one WT and one GXT on separate days in randomised order. During the tests, we estimated cardiac output using inert gas rebreathing (nitrous oxide and sulphur hexafluoride) and subsequently calculated stroke volume. We found that cardiac output was similar (18.2 ± 3.3 vs. 17.9 ± 2.6 l min(-1); P = 0.744), stroke volume was higher (127 ± 37 vs. 94 ± 15 ml; P < 0.001), and heart rate was lower (149 ± 26 vs. 190 ± 12 beats min(-1); P < 0.001) at the end (27 ± 2 s) of a WT as compared to peak exercise during a GXT. Our results suggest that a single WT produces a haemodynamic response which is characterised by similar cardiac output, higher stroke volume and lower heart rate as compared to peak exercise during a GXT.

  15. Measurement of the total acoustic output power of HITU transducers

    NASA Astrophysics Data System (ADS)

    Jenderka, Klaus-V.; Beissner, Klaus

    2010-03-01

    The majority of High Intensity Therapeutic Ultrasound (HITU) applications use strongly focused ultrasound fields generating very high local intensities in the focal region. The metrology of these high-power ultrasound fields is a challenge for the established measurement procedures and devices. This paper describes the results of measurements by means of the radiation force for a total acoustic output power up to 400 W at 1.5 MHz and up to 200 W at 2.45 MHz. For this purpose, a radiation force balance set-up was adapted for the determination of large acoustic output powers. For two types of HITU transducers, the relationship between the total acoustic output power and the applied net electrical power was determined at close transducer-target distance. Further, dependence of the measured electro-acoustic radiation conductance on the transducer-target distance was investigated at reduced power levels, considering the appearance of focal anomalies. Concluding, a list of the main uncertainty contributions, and an estimate of the uncertainty for the used radiation force balance set-up is given for measurements at high power levels.

  16. Leaning during chest compressions impairs cardiac output and left ventricular myocardial blood flow in piglet cardiac arrest

    PubMed Central

    Zuercher, Mathias; Hilwig, Ronald W.; Ranger-Moore, James; Nysaether, Jon; Nadkarni, Vinay M.; Berg, Marc D.; Kern, Karl B.; Sutton, Robert; Berg, Robert A.

    2012-01-01

    Objective Complete recoil of the chest wall between chest compressions during cardiopulmonary resuscitation is recommended, because incomplete chest wall recoil from leaning may decrease venous return and thereby decrease blood flow. We evaluated the hemodynamic effect of 10% or 20% lean during piglet cardiopulmonary resuscitation. Design Prospective, sequential, controlled experimental animal investigation. Setting University research laboratory. Subjects Domestic piglets. Interventions After induction of ventricular fibrillation, cardiopulmonary resuscitation was provided to ten piglets (10.7 ± 1.2 kg) for 18 mins as six 3-min epochs with no lean, 10% lean, or 20% lean to maintain aortic systolic pressure of 80–90 mm Hg. Because the mean force to attain 80–90 mm Hg was 18 kg in preliminary studies, the equivalent of 10% and 20% lean was provided by use of 1.8- and 3.6-kg weights on the chest. Measurements and Main Results Using a linear mixed-effect regression model to control for changes in cardiopulmonary resuscitation hemodynamics over time, mean right atrial diastolic pressure was 9 ± 0.6 mm Hg with no lean, 10 ± 0.3 mm Hg with 10% lean (p < .01), and 13 ± 0.3 mm Hg with 20% lean (p < .01), resulting in decreased coronary perfusion pressure with leaning. Microsphere-determined cardiac index and left ventricular myocardial blood flow were lower with 10% and 20% leaning throughout the 18 mins of cardiopulmonary resuscitation. Mean cardiac index decreased from 1.9 ± 0.2 L · M–2 · min–1 with no leaning to 1.6 ± 0.1 L · M–2 · min–1 with 10% leaning, and 1.4 ± 0.2 L · M–2 · min–1 with 20% leaning (p < .05). The myocardial blood flow decreased from 39 ± 7 mL · min–1 · 100 g–1 with no lean to 30 ± 6 mL · min–1 · 100 g–1 with 10% leaning and 26 ± 6 mL · min–1 · 100 g–1 with 20% leaning (p < .05). Conclusions Leaning of 10% to 20% (i.e., 1.8–3.6 kg) during cardiopulmonary resuscitation substantially decreased coronary

  17. Reliability of a new 4th generation FloTrac algorithm to track cardiac output changes in patients receiving phenylephrine.

    PubMed

    Ji, Fuhai; Li, Jian; Fleming, Neal; Rose, David; Liu, Hong

    2015-08-01

    Phenylephrine is often used to treat intra-operative hypotension. Previous studies have shown that the FloTrac cardiac monitor may overestimate cardiac output (CO) changes following phenylephrine administration. A new algorithm (4th generation) has been developed to improve performance in this setting. We performed a prospective observational study to assess the effects of phenylephrine administration on CO values measured by the 3rd and 4th generation FloTrac algorithms. 54 patients were enrolled in this study. We used the Nexfin, a pulse contour method shown to be insensitive to vasopressor administration, as the reference method. Radial arterial pressures were recorded continuously in patients undergoing surgery. Phenylephrine administration times were documented. Arterial pressure recordings were subsequently analyzed offline using three different pulse contour analysis algorithms: FloTrac 3rd generation (G3), FloTrac 4th generation (G4), and Nexfin (nf). One minute of hemodynamic measurements was analyzed immediately before phenylephrine administration and then repeated when the mean arterial pressure peaked. A total of 157 (4.6 ± 3.2 per patient, range 1-15) paired sets of hemodynamic recordings were analyzed. Phenylephrine induced a significant increase in stroke volume (SV) and CO with the FloTrac G3, but not with FloTrac G4 or Nexfin algorithms. Agreement between FloTrac G3 and Nexfin was: 0.23 ± 1.19 l/min and concordance was 51.1%. In contrast, agreement between FloTrac G4 and Nexfin was: 0.19 ± 0.86 l/min and concordance was 87.2%. In conclusion, the pulse contour method of measuring CO, as implemented in FloTrac 4th generation algorithm, has significantly improved its ability to track the changes in CO induced by phenylephrine.

  18. Measuring fluid flow and heat output in seafloor hydrothermal environments

    NASA Astrophysics Data System (ADS)

    Germanovich, Leonid N.; Hurt, Robert S.; Smith, Joshua E.; Genc, Gence; Lowell, Robert P.

    2015-12-01

    We review techniques for measuring fluid flow and advective heat output from seafloor hydrothermal systems and describe new anemometer and turbine flowmeter devices we have designed, built, calibrated, and tested. These devices allow measuring fluid velocity at high- and low-temperature focused and diffuse discharge sites at oceanic spreading centers. The devices perform at ocean floor depths and black smoker temperatures and can be used to measure flow rates ranging over 2 orders of magnitude. Flow velocity is determined from the rotation rate of the rotor blades or paddle assembly. These devices have an open bearing design that eliminates clogging by particles or chemical precipitates as the fluid passes by the rotors. The devices are compact and lightweight enough for deployment from either an occupied or remotely operated submersible. The measured flow rates can be used in conjunction with vent temperature or geochemical measurements to obtain heat outputs or geochemical fluxes from both vent chimneys and diffuse flow regions. The devices have been tested on 30 Alvin dives on the Juan de Fuca Ridge and 3 Jason dives on the East Pacific Rise (EPR). We measured an anomalously low entrainment coefficient (0.064) and report 104 new measurements over a wide range of discharge temperatures (5°-363°C), velocities (2-199 cm/s), and depths (1517-2511 m). These include the first advective heat output measurements at the High Rise vent field and the first direct fluid flow measurement at Middle Valley. Our data suggest that black smoker heat output at the Main Endeavour vent field may have declined since 1994 and that after the 2005-2006 eruption, the high-temperature advective flow at the EPR 9°50'N field may have become more channelized, predominately discharging through the Bio 9 structure. We also report 16 measurements on 10 Alvin dives and 2 Jason dives with flow meters that predate devices described in this work and were used in the process of their development

  19. Cardiac output method comparison studies: the relation of the precision of agreement and the precision of method.

    PubMed

    Hapfelmeier, Alexander; Cecconi, Maurizio; Saugel, Bernd

    2016-04-01

    Cardiac output (CO) plays a crucial role in the hemodynamic management of critically ill patients treated in the intensive care unit and in surgical patients undergoing major surgery. In the field of cardiovascular dynamics, innovative techniques for CO determination are increasingly available. Therefore, the number of studies comparing these techniques with a reference, such as pulmonary artery thermodilution, is rapidly growing. There are mainly two outcomes of such method comparison studies: (1) the accuracy of agreement and (2) the precision of agreement. The precision of agreement depends on the precision of each method, i.e., the precision that the studied and the reference technique are able to achieve. We call this "precision of method". A decomposition of variance shows that method agreement does not only depend on the precision of method but also on another important source of variability, i.e., the method's general variability about the true values. Ignorance of that fact leads to falsified conclusions about the precision of method of the studied technique. In CO studies, serial measurements are frequently confused with repeated measurements. But as the actual CO of a subject changes from assessment to assessment, there is no real repetition of a measurement. This situation equals a scenario in which single measurements are given for multiple true values per subject. In such a case it is not possible to assess the precision of method.

  20. Kinetics of Cardiac Output at the Onset of Exercise in Precapillary Pulmonary Hypertension.

    PubMed

    Lador, Frédéric; Bringard, Aurélien; Bengueddache, Samir; Ferretti, Guido; Bendjelid, Karim; Soccal, Paola M; Noble, Stéphane; Beghetti, Maurice; Chemla, Denis; Hervé, Philippe; Sitbon, Olivier

    2016-01-01

    Purpose. Cardiac output (CO) is a cornerstone parameter in precapillary pulmonary hypertension (PH). The Modelflow (MF) method offers a reliable noninvasive determination of its beat-by-beat changes. So MF allows exploration of CO adjustment with the best temporal resolution. Methods. Fifteen subjects (5 PH patients, 10 healthy controls) performed a submaximal supine exercise on a cycle ergometer after 5 min of rest. CO was continuously determined by MF (COMF). Kinetics of heart rate (HR), stroke volume (SV), and CO were determined with 3 monoexponential models. Results. In PH patients, we observed a sudden and transitory drop of SV upon exercise onset. This implied a transitory drop of CO whose adjustment to a new steady state depended on HR increase. The kinetics of HR and CO for PH patients was slower than that of controls for all models and for SV in model 1. SV kinetics was faster for PH patients in models 2 and 3. Conclusion. This is the first description of beat-by-beat cardiovascular adjustments upon exercise onset in PH. The kinetics of HR and CO appeared slower than those of healthy controls and there was a transitory drop of CO upon exercise onset in PH due to a sudden drop of SV.

  1. Cardiac output and regional oxygen transport in the acutely hypoxic conscious sheep.

    PubMed

    Nesarajah, M S; Matalon, S; Krasney, J A; Farhi, L E

    1983-08-01

    We have studied the effects of severe acute hypoxemia (PaO2 = 25 torr) on cardiac output (Q), heart rate (HR), left ventricular contractility ((dP/dt)max/P), intravascular pressures and blood flow to the heart, brain, abdominal viscera, skin and respiratory and non-respiratory muscles in twelve conscious ewes that breathed a mixture of 8% O2 and 92% N2 for 20 min. Q, HR, (dP/dt)max/P) and systemic and pulmonary arterial pressures increased. Total peripheral resistance decreased while pulmonary vascular resistance remained unchanged. Coronary, cerebral, respiratory and nonrespiratory muscle and adrenal flows increased, in association with a decrease in regional vascular resistances, while the flows to the kidney and other abdominal viscera remained unchanged. The concentration of total plasma catecholamines doubled, indicating that the sympathetic nervous system plays a major role in the hemodynamic response to this level of hypoxia. Increased oxygen delivery to the heart (31%) and respiratory muscles (44%) were brought about by increases in both the magnitude and the redistribution of Q, the latter being the more important of the two mechanisms. In contrast, both mechanisms contributed equally to the amount of oxygen delivered to the brain and nonrespiratory muscles. We concluded that in acute hypoxemia, both the increase in Q and its regional redistribution contribute to the delivery of oxygen to the various tissues.

  2. High Output Cardiac Failure Resolving after Repair of AV Fistula in a Six-Month-Old

    PubMed Central

    Teomete, Uygar; Gugol, Rubee Anne; Neville, Holly; Dandin, Ozgur; Young, Ming-Lon

    2016-01-01

    Background. Acquired AVF in pediatrics are commonly caused by iatrogenic means, including arterial or venous punctures. These fistulae can cause great hemodynamic stress on the heart as soon as they are created. Case. A six-month-old 25-week gestation infant was referred for respiratory distress. Initial exam revealed tachypnea, tachycardia, and hypertension. There was a bruit noted on her left arm. An ultrasound showed an arteriovenous fistula. Its location, however, precluded intervention because of the high risk for limb-loss. An echocardiogram showed evidence of pulmonary hypertension that was treated with sildenafil and furosemide. However, no improvement was seen. On temporary manual occlusion of the fistula, the patient was noted to have increased her blood pressure and decreased her heart rate, suggesting significant hemodynamic effect of the fistula. The fistula was subsequently ligated and the patient clinically and echocardiographically improved. Conclusion. A patient in high output cardiac failure or pulmonary artery hypertension, especially prematüre patients with preexisting lung disease, should be probed for history of multiple punctures, trauma, or surgery and should have prompt evaluation for AVF. If it can be diagnosed and repaired, most of the cases have been shown to decrease the stress on the heart and reverse the pathologic hemodynamics. PMID:26885434

  3. High Output Cardiac Failure Resolving after Repair of AV Fistula in a Six-Month-Old.

    PubMed

    Teomete, Uygar; Gugol, Rubee Anne; Neville, Holly; Dandin, Ozgur; Young, Ming-Lon

    2016-01-01

    Background. Acquired AVF in pediatrics are commonly caused by iatrogenic means, including arterial or venous punctures. These fistulae can cause great hemodynamic stress on the heart as soon as they are created. Case. A six-month-old 25-week gestation infant was referred for respiratory distress. Initial exam revealed tachypnea, tachycardia, and hypertension. There was a bruit noted on her left arm. An ultrasound showed an arteriovenous fistula. Its location, however, precluded intervention because of the high risk for limb-loss. An echocardiogram showed evidence of pulmonary hypertension that was treated with sildenafil and furosemide. However, no improvement was seen. On temporary manual occlusion of the fistula, the patient was noted to have increased her blood pressure and decreased her heart rate, suggesting significant hemodynamic effect of the fistula. The fistula was subsequently ligated and the patient clinically and echocardiographically improved. Conclusion. A patient in high output cardiac failure or pulmonary artery hypertension, especially prematüre patients with preexisting lung disease, should be probed for history of multiple punctures, trauma, or surgery and should have prompt evaluation for AVF. If it can be diagnosed and repaired, most of the cases have been shown to decrease the stress on the heart and reverse the pathologic hemodynamics.

  4. Cardiac output and associated left ventricular hypertrophy in pediatric chronic kidney disease.

    PubMed

    Weaver, Donald J; Kimball, Thomas R; Koury, Phillip R; Mitsnefes, Mark M

    2009-03-01

    A significant number of children with chronic kidney disease (CKD) have eccentric left ventricular hypertrophy (LVH), suggesting the role of preload overload. Therefore, we hypothesized that increased cardiac output (CO) might be a contributing factor for increased left ventricular mass index (LVMI) in these children. Patients aged 6-20 years with CKD stages 2-4 were enrolled. Echocardiograms were performed to assess LV function and geometry at rest and during exercise. Heart rate, stroke volume, and CO were also assessed at rest and during exercise. Twenty-four-hour ambulatory blood pressure (AMBP) monitoring was performed. Of the patients enrolled in this study, 17% had LVH. Increased stroke volume and CO were observed in patients with LVH compared to patients without LVH. Univariate analysis revealed significant positive associations between LVMI and CO, stroke volume, body mass index, pulse pressure from mean 24-h AMBP, and mean 24-h systolic BP load. No association with heart rate, age, parathyroid hormone, glomerular filtration rate, or anemia was observed. Only CO (beta = 1.98, p = 0.0005) was independently associated with increased LVMI in multivariate modeling (model R (2) = 0.25). The results of this study suggest that increased CO might predispose to increased LVMI in pediatric patients with CKD. Adaptations may be required to meet increased metabolic demand in these patients.

  5. Kinetics of Cardiac Output at the Onset of Exercise in Precapillary Pulmonary Hypertension

    PubMed Central

    Bengueddache, Samir; Ferretti, Guido; Soccal, Paola M.; Noble, Stéphane; Beghetti, Maurice; Chemla, Denis; Hervé, Philippe; Sitbon, Olivier

    2016-01-01

    Purpose. Cardiac output (CO) is a cornerstone parameter in precapillary pulmonary hypertension (PH). The Modelflow (MF) method offers a reliable noninvasive determination of its beat-by-beat changes. So MF allows exploration of CO adjustment with the best temporal resolution. Methods. Fifteen subjects (5 PH patients, 10 healthy controls) performed a submaximal supine exercise on a cycle ergometer after 5 min of rest. CO was continuously determined by MF (COMF). Kinetics of heart rate (HR), stroke volume (SV), and CO were determined with 3 monoexponential models. Results. In PH patients, we observed a sudden and transitory drop of SV upon exercise onset. This implied a transitory drop of CO whose adjustment to a new steady state depended on HR increase. The kinetics of HR and CO for PH patients was slower than that of controls for all models and for SV in model 1. SV kinetics was faster for PH patients in models 2 and 3. Conclusion. This is the first description of beat-by-beat cardiovascular adjustments upon exercise onset in PH. The kinetics of HR and CO appeared slower than those of healthy controls and there was a transitory drop of CO upon exercise onset in PH due to a sudden drop of SV. PMID:27990432

  6. A computational model-based validation of Guyton's analysis of cardiac output and venous return curves

    NASA Technical Reports Server (NTRS)

    Mukkamala, R.; Cohen, R. J.; Mark, R. G.

    2002-01-01

    Guyton developed a popular approach for understanding the factors responsible for cardiac output (CO) regulation in which 1) the heart-lung unit and systemic circulation are independently characterized via CO and venous return (VR) curves, and 2) average CO and right atrial pressure (RAP) of the intact circulation are predicted by graphically intersecting the curves. However, this approach is virtually impossible to verify experimentally. We theoretically evaluated the approach with respect to a nonlinear, computational model of the pulsatile heart and circulation. We developed two sets of open circulation models to generate CO and VR curves, differing by the manner in which average RAP was varied. One set applied constant RAPs, while the other set applied pulsatile RAPs. Accurate prediction of intact, average CO and RAP was achieved only by intersecting the CO and VR curves generated with pulsatile RAPs because of the pulsatility and nonlinearity (e.g., systemic venous collapse) of the intact model. The CO and VR curves generated with pulsatile RAPs were also practically independent. This theoretical study therefore supports the validity of Guyton's graphical analysis.

  7. Cardiac output: a central issue in patients with respiratory extracorporeal support.

    PubMed

    Romagnoli, Stefano; Zagli, Giovanni; Ricci, Zaccaria; Villa, Gianluca; Barbani, Francesco; Pinelli, Fulvio; De Gaudio, Raffaele; Chelazzi, Cosimo

    2017-01-01

    The iLA-activve(®) Novalung is a new extracorporeal device specifically designed for lung support in patients with hypercapnic and/or hypoxemic respiratory failure. To date, only low-flow applications for decompensated hypercapnic chronic obstructive pulmonary disease have been reported in the literature. Here, we briefly report three cases of iLA-activve use in patients with hypercapnic-hypoxemic acute lung failure assisted with mid-flow (up to 2.4 L/min) and different single/double venous cannulation. The main findings of our small case series were: firstly, extracorporeal blood flows over 2.0 L/min across the membrane provided clinically satisfying decarboxylation and improved oxygenation; secondly, the ratio between blood flow through the membrane and the patient's cardiac output (CO) was a major determinant for the oxygen increase. The latter could, therefore, be a useful indicator for understanding performance in the complex and multifactorial evaluation of patients with extracorporeal veno-venous lung support.

  8. Evaluation of cardiac output in intensive care using a non-invasive arterial pulse contour technique (Nexfin(®)) compared with echocardiography.

    PubMed

    Taton, O; Fagnoul, D; De Backer, D; Vincent, J-L

    2013-09-01

    In this prospective study, cardiac output was measured in 38 intensive care unit patients before and after a fluid challenge, using both pulse contour analysis (Nexfin(®); BMEYE, Amsterdam, the Netherlands) and transthoracic echocardiography. The ability of the Nexfin device to detect significant changes in the velocity-time integral was evaluated. The pulse wave could not be detected by the Nexfin device in five patients (13%), leaving 33 patients for analysis. The Nexfin device adequately tracked changes in the velocity-time integral in 20 (61%) patients. Using a cut-off of a 10% increase in cardiac output estimated by the Nexfin or by echocardiography, the sensitivity of the Nexfin device to detect a response to fluid challenge was 47%, with specificity 81% and accuracy 64%. The percentage error between the Nexfin and echocardiography was 448%; lower limit of agreement -48% (95% CI -62 to -36%) and upper limit of agreement, 32% (95% CI 20-45%). We conclude that the Nexfin device does not adequately track changes in cardiac output in critically ill patients.

  9. PP097. Cardiac output and systemic vascular resistance in normal pregnancy and in control non-pregnant women.

    PubMed

    Khalil, A; Goodyear, Gemma; Joseph, Ehizele; Khalil, Asma

    2012-07-01

    Changes in cardiac output (CO) and systemic vascular resistance (SVR) have been shown to precede the clinical onset of pregnancy complications, such as pre-eclampsia and fetal growth restriction. CO and SVR undergo major changes during normal pregnancy. However, assessment of these vascular parameters requires intensive training and expensive techniques, so currently can be performed only in specialised centres. The aim of this study was to investigate maternal cardiovascular function measured using an ultrasonic cardiac output monitor (USCOM), a simple non-invasive continuous wave Doppler device, in a cohort of pregnant women and non-pregnant controls. This was a cross sectional study including 185 women with normal singleton pregnancies at 11-40weeks of gestation and 49 non-pregnant controls. Stroke volume (SV), CO and SVR were measured using the USCOM device. All measurements were performed with the patients in supine position. All women with a gestational age of >20weeks were in a left lateral position by placing a wedge-shaped pillow under their right side to prevent vena cava compression. In a group of 25 pregnant women, each measurement was repeated three times to evaluate the reproducibility of this technique. Cardiac index (CI), SV index (SVI) and SVR index (SVRI) relate CO, SV and SVR to the body surface area. The data were normally distributed after logarithmic transformation. Comparisons between pregnant and non-pregnant women were performed using Studentt-test, Chi-Square test or multiple regression analysis, when adjustment for potential confounders was necessary. Data analysis was performed using SPSS 16.0. In the first trimester, all of the following vascular parameters were higher in pregnant women compared to non-pregnant controls: CO [median (IQR): 4.86 (4.45-5.57) vs 5.57 (4.76-6.52)L/min, P<0.001], CI [median (IQR): 2.69 (2.44-3.07) vs 3.25 (2.80-3.86)L/min/m(2), P<0.001], SV [median (IQR): 72.51 (68.10-80.18) vs 80.75 (74.50-99.74)mL/beat, P<0

  10. Prediction of pregnancy complication occurrence using fetal cardiac output assessments made by ultrasonography at 20 to 24 weeks of gestation.

    PubMed

    Lee, Ji Yeon; Kim, Young Li; Jeong, Ji Eun; Ahn, Jun Woo

    2017-07-01

    To evaluate the importance of assessment of fetal cardiac output (CO) for the prediction of complications of pregnancy. We evaluated 65 fetuses and all of them had a fetal cardiac scan at 20 to 24 weeks of pregnancy. To measure CO, diameters (d) of the left right ventricle outflow tract were measured just above the valves. Each left CO (LCO) and right CO (RCO) was derived using the following equation: CO = velocity time integral × π × d(2)/4 × heart rate. Pregnancy complications included gestational hypertensive disorders, fetal growth restriction (FGR) and preterm birth (PTB) caused from preterm labor or preterm premature rupture of membrane (PPROM). There were 23 cases with one more pregnancy complication (FGR, 9; gestational hypertensive disorders, 8; PTB caused from PTB or PPROM, 12). The LCO was lower in complication group than in normal group (88±53 vs. 117±48 mL/min, P=0.028). The RCO to the LCO ratio (RCO/LCO) was higher in complication group (2.43±1.69 vs. 1.48±0.81, P=0.001). Regression analysis demonstrated that RCO/LCO was a significant predictor of pregnancy complication; Odds ratio was 7.76 (95% CI, 1.15 to 52.21; P=0.029). The area under the receiver-operating characteristic curve for prediction of pregnancy complications from LCO was 0.71. The diagnostic cut-off value of LCO was 80 mL/min. The area under the receiver-operating characteristic curve from RCO/LCO was 0.68 and cut-off value was 1.41. This study demonstrated that pregnancy complications can be suspected based on fetal CO assessments at a GA of 20 to 24 weeks.

  11. Validation of cardiac accelerometer sensor measurements.

    PubMed

    Remme, Espen W; Hoff, Lars; Halvorsen, Per Steinar; Naerum, Edvard; Skulstad, Helge; Fleischer, Lars A; Elle, Ole Jakob; Fosse, Erik

    2009-12-01

    In this study we have investigated the accuracy of an accelerometer sensor designed for the measurement of cardiac motion and automatic detection of motion abnormalities caused by myocardial ischaemia. The accelerometer, attached to the left ventricular wall, changed its orientation relative to the direction of gravity during the cardiac cycle. This caused a varying gravity component in the measured acceleration signal that introduced an error in the calculation of myocardial motion. Circumferential displacement, velocity and rotation of the left ventricular apical region were calculated from the measured acceleration signal. We developed a mathematical method to separate translational and gravitational acceleration components based on a priori assumptions of myocardial motion. The accuracy of the measured motion was investigated by comparison with known motion of a robot arm programmed to move like the heart wall. The accuracy was also investigated in an animal study. The sensor measurements were compared with simultaneously recorded motion from a robot arm attached next to the sensor on the heart and with measured motion by echocardiography and a video camera. The developed compensation method for the varying gravity component improved the accuracy of the calculated velocity and displacement traces, giving very good agreement with the reference methods.

  12. Children with Burn Injury Have Impaired Cardiac Output during Submaximal Exercise.

    PubMed

    Rivas, Eric; Herndon, David N; Beck, Kenneth C; Suman, Oscar E

    2017-10-01

    Burn trauma damages resting cardiac function; however, it is currently unknown if the cardiovascular response to exercise is likewise impaired. We tested the hypothesis that, in children, burn injury lowers cardiac output (Q˙) and stroke volume (SV) during submaximal exercise. Five children with 49% ± 4% total body surface area (BSA) burned (two female, 11.7 ± 1 yr, 40.4 ± 18 kg, 141.1 ± 9 cm) and eight similar nonburned controls (five female, 12.5 ± 2 yr, 58.0 ± 17 kg, 147.3 ± 12 cm) with comparable exercise capacity (peak oxygen consumption [peak V˙O2]: 31.9 ± 11 vs 36.8 ± 8 mL O2·kg·min, P = 0.39) participated. The exercise protocol entailed a preexercise (pre-EX) rest period followed by 3-min exercise stages at 20 W and 50 W. V˙O2, HR, Q˙ (via nonrebreathing), SV (Q˙/HR), and arteriovenous O2 difference ([a-v]O2diff, Q˙/ V˙O2) were the primary outcome variables. Using a 2-way factorial ANOVA (group [G] × exercise [EX]), we found that Q˙ was approximately 27% lower in the burned than the nonburned group at 20 W of exercise (burned 5.7 ± 1.0 vs nonburned: 7.9 ± 1.8 L·min) and 50 W of exercise (burned 6.9 ± 1.6 vs nonburned 9.2 ± 3.2 L·min) (G-EX interaction, P = 0.012). SV did not change from rest to exercise in burned children but increased by approximately 24% in the nonburned group (main effect for EX, P = 0.046). Neither [a-v] O2diff nor V˙O2 differed between groups at rest or exercise, but HR response to exercise was reduced in the burn group (G-EX interaction, P = 0.004). When normalized to BSA, SV (index) was similar between groups; however, Q˙ (index) remained attenuated in the burned group (G-EX interaction, P < 0.008). Burned children have an attenuated cardiovascular response to submaximal exercise. Further investigation of hemodynamic function during exercise will provide insights important for cardiovascular rehabilitation in burned children.

  13. Noninvasive ambulatory measurement system of cardiac activity.

    PubMed

    Pino, Esteban J; Chavez, Javier A P; Aqueveque, Pablo

    2015-01-01

    This work implements a noninvasive system that measures the movements caused by cardiac activity. It uses unobtrusive Electro-Mechanical Films (EMFi) on the seat and on the backrest of a regular chair. The system detects ballistocardiogram (BCG) and respiration movements. Real data was obtained from 54 volunteers. 19 of them were measured in the laboratory and 35 in a hospital waiting room. Using a BIOPAC acquisition system, the ECG was measured simultaneously to the BCG for comparison. Wavelet Transform (WT) is a better option than Empirical Mode Decomposition (EMD) for signal extraction and produces higher effective measurement time. In the laboratory, the best results are obtained on the seat. The correlation index was 0.9800 and the Bland-Altman limits of agreement were 0.7136 ± 4.3673 [BPM]. In the hospital waiting room, the best results are also from the seat sensor. The correlation index was 0.9840, and the limits of agreement were 0.4386 ± 3.5884 [BPM]. The system is able to measure BCG in an unobtrusive way and determine the cardiac frequency with high precision. It is simple to use, which means the system can easily be used in non-standard settings: resting in a chair or couch, at the gym, schools or in a hospital waiting room, as shown.

  14. Reduced peripheral arterial blood flow with preserved cardiac output during submaximal bicycle exercise in elderly heart failure

    PubMed Central

    2009-01-01

    Background Older heart failure (HF) patients exhibit exercise intolerance during activities of daily living. We hypothesized that reduced lower extremity blood flow (LBF) due to reduced forward cardiac output would contribute to submaximal exercise intolerance in older HF patients. Methods and Results Twelve HF patients both with preserved and reduced left ventricular ejection fraction (LVEF) (aged 68 ± 10 years) without large (aorta) or medium sized (iliac or femoral artery) vessel atherosclerosis, and 13 age and gender matched healthy volunteers underwent a sophisticated battery of assessments including a) peak exercise oxygen consumption (peak VO2), b) physical function, c) cardiovascular magnetic resonance (CMR) submaximal exercise measures of aortic and femoral arterial blood flow, and d) determination of thigh muscle area. Peak VO2 was reduced in HF subjects (14 ± 3 ml/kg/min) compared to healthy elderly subjects (20 ± 6 ml/kg/min) (p = 0.01). Four-meter walk speed was 1.35 ± 0.24 m/sec in healthy elderly verses 0.98 ± 0.15 m/sec in HF subjects (p < 0.001). After submaximal exercise, the change in superficial femoral LBF was reduced in HF participants (79 ± 92 ml/min) compared to healthy elderly (222 ± 108 ml/min; p = 0.002). This occurred even though submaximal stress-induced measures of the flow in the descending aorta (5.0 ± 1.2 vs. 5.1 ± 1.3 L/min; p = 0.87), and the stress-resting baseline difference in aortic flow (1.6 ± 0.8 vs. 1.7 ± 0.8 L/min; p = 0.75) were similar between the 2 groups. Importantly, the difference in submaximal exercise induced superficial femoral LBF between the 2 groups persisted after accounting for age, gender, body surface area, LVEF, and thigh muscle area (p ≤ 0.03). Conclusion During CMR submaximal bike exercise in the elderly with heart failure, mechanisms other than low cardiac output are responsible for reduced lower extremity blood flow. PMID:19922666

  15. Combined first pass and gated blood pool radionuclide studies in the hemodynamic-cardiac evaluation of patients with low cardiac output

    SciTech Connect

    Abi-Mansour, P.; Fouad, F.M.; Sheeler, L.R.; Bravo, E.L.; MacIntyre, W.J.; Tarazi, R.C.

    1984-01-01

    Cardiac output (CO) is frequently used in the evaluation of cardiac function but low CO does not necessarily reflect heart failure. Similarly, low ejection fraction (EF) can be present in compensated heart diseases. In order to evaluate cardiac performance in relation to systematic hemodynamics, the authors used a multifactorial approach for the determination of CO, EF, pulmonary mean transit time (MTT), ratio of cardiopulmonary volume over total blood volume (CPV/TBV as an index of venous tone) all obtained from a single injection of 99m Tc-HSA. Four different conditions associated with low CO (less than or equal to 2.1 L/min/m/sup 2/) were evaluated. The combined use of CO, EF, MTT and CPV/TBV allowed a better understanding of the myocardial and peripheral circulatory factors associated with low CO states. This is helpful in the selection and follow-up of appropriate therapeutic intervention.

  16. Ultrasonic Power Output Measurement by Pulsed Radiation Pressure.

    PubMed

    Fick, Steven E; Breckenridge, Franklin R

    1996-01-01

    Direct measurements of time-averaged spatially integrated output power radiated into reflectionless water loads can be made with high accuracy using techniques which exploit the radiation pressure exerted by sound on all objects in its path. With an absorptive target arranged to intercept the entirety of an ultrasound beam, total beam power can be determined as accurately as the radiation force induced on the target can be measured in isolation from confounding forces due to buoyancy, streaming, surface tension, and vibration. Pulse modulation of the incident ultrasound at a frequency well above those characteristics of confounding phenomena provides the desired isolation and other significant advantages in the operation of the radiation force balance (RFB) constructed in 1974. Equipped with purpose-built transducers and electronics, the RFB is adjusted to equate the radiation force and a counterforce generated by an actuator calibrated against reference masses using direct current as the transfer variable. Improvements made during its one overhaul in 1988 have nearly halved its overall measurement uncertainty and extended the capabilities of the RFB to include measuring the output of ultrasonic systems with arbitrary pulse waveforms.

  17. Ultrasonic Power Output Measurement by Pulsed Radiation Pressure

    PubMed Central

    Fick, Steven E.; Breckenridge, Franklin R.

    1996-01-01

    Direct measurements of time-averaged spatially integrated output power radiated into reflectionless water loads can be made with high accuracy using techniques which exploit the radiation pressure exerted by sound on all objects in its path. With an absorptive target arranged to intercept the entirety of an ultrasound beam, total beam power can be determined as accurately as the radiation force induced on the target can be measured in isolation from confounding forces due to buoyancy, streaming, surface tension, and vibration. Pulse modulation of the incident ultrasound at a frequency well above those characteristics of confounding phenomena provides the desired isolation and other significant advantages in the operation of the radiation force balance (RFB) constructed in 1974. Equipped with purpose-built transducers and electronics, the RFB is adjusted to equate the radiation force and a counterforce generated by an actuator calibrated against reference masses using direct current as the transfer variable. Improvements made during its one overhaul in 1988 have nearly halved its overall measurement uncertainty and extended the capabilities of the RFB to include measuring the output of ultrasonic systems with arbitrary pulse waveforms. PMID:27805084

  18. Omega-3 fatty acid supplementation enhances stroke volume and cardiac output during dynamic exercise.

    PubMed

    Walser, Buddy; Stebbins, Charles L

    2008-10-01

    Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) have beneficial effects on cardiovascular function. We tested the hypotheses that dietary supplementation with DHA (2 g/day) + EPA (3 g/day) enhances increases in stroke volume (SV) and cardiac output (CO) and decreases in systemic vascular resistance (SVR) during dynamic exercise. Healthy subjects received DHA + EPA (eight men, four women) or safflower oil (six men, three women) for 6 weeks. Both groups performed 20 min of bicycle exercise (10 min each at a low and moderate work intensity) before and after DHA + EPA or safflower oil treatment. Mean arterial pressure (MAP), heart rate (HR), SV, CO, and SVR were assessed before exercise and during both workloads. HR was unaffected by DHA + EPA and MAP was reduced, but only at rest (88 +/- 5 vs. 83 +/- 4 mm Hg). DHA + EPA augmented increases in SV (14.1 +/- 6.3 vs. 32.3 +/- 8.7 ml) and CO (8.5 +/- 1.0 vs. 10.3 +/- 1.2 L/min) and tended to attenuate decreases in SVR (-7.0 +/- 0.6 vs. -10.1 +/- 1.6 mm Hg L(-1) min(-1)) during the moderate workload. Safflower oil treatment had no effects on MAP, HR, SV, CO or SVR at rest or during exercise. DHA + EPA-induced increases in SV and CO imply that dietary supplementation with these fatty acids can increase oxygen delivery during exercise, which may have beneficial clinical implications for individuals with cardiovascular disease and reduced exercise tolerance.

  19. Phlebotomy eliminates the maximal cardiac output response to six weeks of exercise training.

    PubMed

    Bonne, Thomas C; Doucende, Gregory; Flück, Daniela; Jacobs, Robert A; Nordsborg, Nikolai B; Robach, Paul; Walther, Guillaume; Lundby, Carsten

    2014-05-15

    With this study we tested the hypothesis that 6 wk of endurance training increases maximal cardiac output (Qmax) relatively more by elevating blood volume (BV) than by inducing structural and functional changes within the heart. Nine healthy but untrained volunteers (Vo2max 47 ± 5 ml·min(-1)·kg(-1)) underwent supervised training (60 min; 4 times weekly at 65% Vo2max for 6 wk), and Qmax was determined by inert gas rebreathing during cycle ergometer exercise before and after the training period. After the training period, blood volume (determined in duplicates by CO rebreathing) was reestablished to pretraining values by phlebotomy and Qmax was quantified again. Resting echography revealed no structural heart adaptations as a consequence of the training intervention. After the training period, plasma volume (PV), red blood cell volume (RBCV), and BV increased (P < 0.05) by 147 ± 168 (5 ± 5%), 235 ± 64 (10 ± 3%), and 382 ± 204 ml (7 ± 4%), respectively. Vo2max was augmented (P < 0.05) by 10 ± 7% after the training period and decreased (P < 0.05) by 8 ± 7% with phlebotomy. Concomitantly, Qmax was increased (P < 0.05) from 18.9 ± 2.1 to 20.4 ± 2.3 l/min (9 ± 6%) as a consequence of the training intervention, and after normalization of BV by phlebotomy Qmax returned to pretraining values (18.1 ± 2.5 l/min; 12 ± 5% reversal). Thus the exercise training-induced increase in BV is the main mechanism increasing Qmax after 6 wk of endurance training in previously untrained subjects.

  20. Assessment of cardiac output with transpulmonary thermodilution during exercise in humans.

    PubMed

    Calbet, José A L; Boushel, Robert

    2015-01-01

    The accuracy and reproducibility of transpulmonary thermodilution (TPTd) to assess cardiac output (Q̇) in exercising men was determined using indocyanine green (ICG) dilution as a reference method. TPTd has been utilized for the assessment of Q̇ and preload indexes of global end-diastolic volume and intrathoracic blood volume, as well as extravascular lung water (EVLW) in resting humans. It remains unknown if this technique is also accurate and reproducible during exercise. Sixteen healthy men underwent catheterization of the right femoral vein (for iced saline injection), an antecubital vein (ICG injection), and femoral artery (thermistor) to determine their Q̇ by TPTd and ICG concentration during incremental one- and two-legged pedaling on a cycle ergometer and combined arm cranking with leg pedaling to exhaustion. There was a close relationship between TPTd-Q̇ and ICG-Q̇ (r = 0.95, n = 151, standard error of the estimate: 1.452 l/min, P < 0.001; mean difference of 0.06 l/min; limits of agreement -2.98 to 2.86 l/min), and TPTd-Q̇ and ICG-Q̇ increased linearly with oxygen uptake with similar intercepts and slopes. Both methods had mean coefficients of variation close to 5% for Q̇, global end-diastolic volume, and intrathoracic blood volume. The mean coefficient of variation of EVLW, assessed with both indicators (ICG and thermal) was 17% and was sensitive enough to detect a reduction in EVLW of 107 ml when changing from resting supine to upright exercise. In summary, TPTd with bolus injection into the femoral vein is an accurate and reproducible method to assess Q̇ during exercise in humans.

  1. Dynamic device properties of pulse contour cardiac output during transcatheter aortic valve implantation.

    PubMed

    Petzoldt, Martin; Riedel, Carsten; Braeunig, Jan; Haas, Sebastian; Goepfert, Matthias S; Treede, Hendrik; Baldus, Stephan; Goetz, Alwin E; Reuter, Daniel A

    2015-06-01

    This prospective single-center study aimed to determine the responsiveness and diagnostic performance of continuous cardiac output (CCO) monitors based on pulse contour analysis compared with invasive mean arterial pressure (MAP) during predefined periods of acute circulatory deterioration in patients undergoing transcatheter aortic valve implantation (TAVI). The ability of calibrated (CCO(CAL)) and self-calibrated (CCO(AUTOCAL)) pulse contour analysis to detect the hemodynamic response to 37 episodes of balloon aortic valvuloplasty enabled by rapid ventricular pacing was quantified in 13 patients undergoing TAVI. A "low" and a "high" cut-off limit were predefined as a 15 or 25 % decrease from baseline respectively. We found no significant differences between CCO(CAL) and MAP regarding mean response time [low cut-off: 8.6 (7.1-10.5) vs. 8.9 (7.3-10.8) s, p = 0.76; high cut-off: 11.4 (9.7-13.5) vs. 12.6 (10.7-14.9) s, p = 0.32] or diagnostic performance [area under the receiver operating characteristics curve (AUC): 0.99 (0.98-1.0) vs. 1.0 (0.99-1.0), p = 0.46]. But CCOCAL had a significantly higher amplitude response [95.0 (88.7-98.8) % decrease from baseline] than MAP [41.2 (30.0-52.9) %, p < 0.001]. CCOAUTOCAL had a significantly lower AUC [0.83 (0.73-0.93), p < 0.001] than MAP. Moreover, CCO(CAL) detected hemodynamic recovery significantly earlier than MAP. In conclusion, CCO(CAL) and MAP provided equivalent responsiveness and diagnostic performance to detect acute circulatory depression, whereas CCO(AUTOCAL) appeared to be less appropriate. In contrast to CCO(CAL) the amplitude response of MAP was poor. Consequently even small response amplitudes of MAP could indicate severe decreases in CO.

  2. Mechanisms of increase in cardiac output during acute weightlessness in humans.

    PubMed

    Petersen, Lonnie G; Damgaard, Morten; Petersen, Johan C G; Norsk, Peter

    2011-08-01

    Based on previous water immersion results, we tested the hypothesis that the acute 0-G-induced increase in cardiac output (CO) is primarily caused by redistribution of blood from the vasculature above the legs to the cardiopulmonary circulation. In seated subjects (n = 8), 20 s of 0 G induced by parabolic flight increased CO by 1.7 ± 0.4 l/min (P < 0.001). This increase was diminished to 0.8 ± 0.4 l/min (P = 0.028), when venous return from the legs was prevented by bilateral venous thigh-cuff inflation (CI) of 60 mmHg. Because the increase in stroke volume during 0 G was unaffected by CI, the lesser increase in CO during 0 G + CI was entirely caused by a lower heart rate (HR). Thus blood from vascular beds above the legs in seated subjects can alone account for some 50% of the increase in CO during acute 0 G. The remaining increase in CO is caused by a higher HR, of which the origin of blood is unresolved. In supine subjects, CO increased from 7.1 ± 0.7 to 7.9 ± 0.8 l/min (P = 0.037) when entering 0 G, which was solely caused by an increase in HR, because stroke volume was unaffected. In conclusion, blood originating from vascular beds above the legs can alone account for one-half of the increase in CO during acute 0 G in seated humans. A Bainbridge-like reflex could be the mechanism for the HR-induced increase in CO during 0 G in particular in supine subjects.

  3. Role of the autonomic nervous system in the reduced maximal cardiac output at altitude.

    PubMed

    Bogaard, Harm J; Hopkins, Susan R; Yamaya, Yoshiki; Niizeki, Kyuichi; Ziegler, Michael G; Wagner, Peter D

    2002-07-01

    After acclimatization to high altitude, maximal exercise cardiac output (QT) is reduced. Possible contributing factors include 1) blood volume depletion, 2) increased blood viscosity, 3) myocardial hypoxia, 4) altered autonomic nervous system (ANS) function affecting maximal heart rate (HR), and 5) reduced flow demand from reduced muscle work capability. We tested the role of the ANS reduction of HR in this phenomenon in five normal subjects by separately blocking the sympathetic and parasympathetic arms of the ANS during maximal exercise after 2-wk acclimatization at 3,800 m to alter maximal HR. We used intravenous doses of 8.0 mg of propranolol and 0.8 mg of glycopyrrolate, respectively. At altitude, peak HR was 170 +/- 6 beats/min, reduced from 186 +/- 3 beats/min (P = 0.012) at sea level. Propranolol further reduced peak HR to 139 +/- 2 beats/min (P = 0.001), whereas glycopyrrolate increased peak HR to sea level values, 184 +/- 3 beats/min, confirming adequate dosing with each drug. In contrast, peak O(2) consumption, work rate, and QT were similar at altitude under all drug treatments [peak QT = 16.2 +/- 1.2 (control), 15.5 +/- 1.3 (propranolol), and 16.2 +/- 1.1 l/min (glycopyrrolate)]. All QT results at altitude were lower than those at sea level (20.0 +/- 1.8 l/min in air). Therefore, this study suggests that, whereas the ANS may affect HR at altitude, peak QT is unaffected by ANS blockade. We conclude that the effect of altered ANS function on HR is not the cause of the reduced maximal QT at altitude.

  4. Dynamic asymmetries of cardiac output transients in response to muscular exercise in man.

    PubMed Central

    Yoshida, T; Whipp, B J

    1994-01-01

    1. We determined the kinetics of cardiac output (Q) with respect to oxygen uptake (VO2) at the on- and off-transients of constant-load exercise. Six subjects performed constant-load exercise which consisted of 5 min rest, 5 min one-legged pedalling at 50 W and a 5 min recovery period. 2. The transient responses were characterized by first-order kinetics. There was no significant difference between the time constants for VO2 (tau VO2) at the on- (33.9 +/- 3.5 s, mean +/- S.E.M.) and off-transient (37.2 +/- 2.9 s). The time constant for Q (tau Q, 29.4 +/- 3.2 s) was consistently shorter than tau VO2 at the on-transient. However, tau Q was appreciably longer at the off-transient (44.3 +/- 3.6 s) than the on-transient. 3. The results support the contention that the time constant for the on-transient of Q is appreciably faster than that for VO2 and hence there seems little justification for the notion that the time constants for the kinetics of VO2 are determined by the limitations of blood flow in the transient. The asymmetry of Q kinetics, with the off-transient tau Q being appreciably slower than the on-transient tau Q, serves to maintain a sufficiently high oxygen flow to the muscle during recovery from exercise at a time when the muscle oxygen uptake remains high. PMID:7869250

  5. [Current approaches to intraoperative diagnosis and treatment of low cardiac output during cardiosurgical operations].

    PubMed

    Iavorovskiĭ, A G; Flerov, E V; Sandrikov, V A; Buniatian, A A

    2006-01-01

    The paper deals with the development of a diagnostic and therapeutic algorithm of intraoperative heart failure during cardiosurgical operations on the basis of evaluation of systolic and diastolic functions of the left and right ventricles. The study included 101 patients with low cardiac output in the postperfusion period. All the patients suffered from coronary heart disease and they underwent myocardial revascularizing operations under extracorporeal circulation. In all the patients, in addition to traditional hemodynamic parameters (heart rate, blood pressure, central venous pressure), the functional status of the left and right ventricles was evaluated by transesophageal Doppler echocardiography (TED echoCG) and the thermodilution technique using a Swan-Ganz catheter having a prompt thermistor. Evaluating the diastolic and diastolic functions of the right and left ventricles makes it possible to identify 2 types of left and right ventricular failure: 1) that due to systolic dysfunction and 2) that due to concomitance of systolic and diastolic dysfunctions. Dobutrex (5-7.5 microg/kg/min) should be used in right ventricular systolic dysfunction. Amrinone (5-10 microg/kg/min) should be given to patients with concomitance of systolic and diastolic dysfunction; in this situation, a combination of dobutrex and nitroglycerin (100-150 ng/kg/min) may be used. The drugs of choice in impaired left ventricular systolic function are epinephrine (30-100 ng/kg/min), dopamine (5-10 microg/kg/min), or dobutrex (5-7.5 microg/kg/min). Their combination with sodium nitroprusside can enhance the efficiency of therapy. In patients with left ventricular failure caused by systolic and diastolic dysfunction, epinephrine, dopamine, or dobutrex may be combined with amrinone (5-10 microg/kg/min) or nitroglycerin (100-150 ng/kg/min).

  6. Increase in cardiac output and PEEP as mechanism of pulmonary optimization.

    PubMed

    Curiel, C; Martínez, R; Pinto, V; Rosales, A; D'Empaire, G; Sánchez De Leon, R

    1995-03-01

    The influence of cardiac output (CO) and PEEP on pulmonary shunt (Qs/Qt) has been the subjects of considerable investigation but findings are controversial. The role of CO and PEEP on 19 isolated rabbit lung preparations perfused with hypoxic mixture (6% CO2, 10% O2, and 84% N2), which resulted in a constant oxygen venous pressure (64 +/- 5.6 mmHg) has been studied. The first group of 11 preparations were used to study the influence of CO modifications with room air ventilation on the Qs/Qt when the CO rises in 48%; in the second group simultaneous modifications in CO and PEEP (0.5 and 10 cm H2O) were performed. A positive correlation (p < 0.01) in Qs/Qt (0.048 +/- 0.04 to 0.12933 +/- 0.09) was found when the CO increased in the first experimental group, the fluid filtration rate (FFR) also increased and the pulmonary vascular resistance (PVR) remained stable. In the second group an increase of 5 and 10 cm H2O of PEEP at constant CO reduced the Qs/Qt (0.0361 +/- 0.02 to 0.0184 +/- 0.006) while it increased the arterio-venous oxygen difference, PVR and FFR. During high CO conditions increase of 5 and 10 cm H2O of PEEP reduced the Qs/Qt (0.099 +/- 0.03 to 0.027 +/- 0.02) and FFR. These data suggest that when the Qs/Qt is increased, the use of PEEP can compensate the ventilation/perfusion alterations and restore pulmonary gas exchange.

  7. Assessment of trending ability of cardiac output monitors by polar plot methodology.

    PubMed

    Critchley, Lester A; Yang, Xiao X; Lee, Anna

    2011-06-01

    To develop a valid statistical method of showing acceptable cardiac output (CO) trending ability when new CO monitors are compared to a reference standard, such as thermodilution, using polar coordinates. Developing a new statistical analytic method using historic data. University Hospital Anesthesia and Intensive Care Department. Data taken from previously published CO validation studies. Cartesian data were reanalyzed, being uplifted using Data Thief 3.0 software (http://datathief.org/). Polar plots were constructed from this data. Central zone data (<0.5 L/min or <10% change) were excluded because they introduced statistical noise. Trial polar criteria were set using data from a study that compared 5 CO monitors against thermodilution. Then, these criteria were further validated using data extracted from 15 other studies. Mean (95% confidence intervals) polar angles were used. Trial data suggest ±5° (angle) ±30° (95% confidence interval) as acceptance limits. Concordance rates (ie, >95%-90%) from 5 articles supported trending, and polar data from these studies concurred with the authors' pilot criteria. Favorable comments on trending also were found in 8 of 15 articles in which radial limits were less than ±32°. Good calibration was associated with a mean polar angle of less than ±5°. Polar plots can be used to show the trending ability of CO monitors in comparative validation studies. They overcome the deficiencies of concordance analysis, which uses the direction of change as a statistic and ignores the magnitude of change in CO. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Measurement of acoustic output power in a traveling wave engine.

    PubMed

    Miwa, M; Sumi, T; Biwa, T; Ueda, Y; Yazaki, T

    2006-12-22

    We built and tested a double-loop thermoacoustic cooler consisting of an engine-loop, a branch resonator, and a cooler-loop. The cooling power of 6.4 W was obtained at the cooling temperature of 0 degrees C, when the input heat power of 416 W was supplied to the engine-loop. We measured the acoustic power and found that the output power emitted from the engine-loop was 12 W, and that the input acoustic power entering the cooler-loop was 6 W.

  9. Hemodynamic monitoring in the critically ill: an overview of current cardiac output monitoring methods

    PubMed Central

    Huygh, Johan; Peeters, Yannick; Bernards, Jelle; Malbrain, Manu L. N. G.

    2016-01-01

    Critically ill patients are often hemodynamically unstable (or at risk of becoming unstable) owing to hypovolemia, cardiac dysfunction, or alterations of vasomotor function, leading to organ dysfunction, deterioration into multi-organ failure, and eventually death. With hemodynamic monitoring, we aim to guide our medical management so as to prevent or treat organ failure and improve the outcomes of our patients. Therapeutic measures may include fluid resuscitation, vasopressors, or inotropic agents. Both resuscitation and de-resuscitation phases can be guided using hemodynamic monitoring. This monitoring itself includes several different techniques, each with its own advantages and disadvantages, and may range from invasive to less- and even non-invasive techniques, calibrated or non-calibrated. This article will discuss the indications and basics of monitoring, further elaborating on the different techniques of monitoring. PMID:28003877

  10. Invasive Hemodynamic Assessment of Cardiac Output State after MitraClip Therapy in Nonanaesthetized Patients with Functional Mitral Regurgitation

    PubMed Central

    Budesinsky, Tomas; Linkova, Hana

    2016-01-01

    Background. Surgical correction of mitral regurgitation (MR) can lead to postoperative low cardiac output state. We aimed to assess the acute hemodynamic changes after percutaneous MitraClip therapy (a unique model without influence of factors linked to surgical procedure) in patients with functional MR without the influence of general anaesthesia. Methods. We studied invasive hemodynamic parameters in 23 patients before procedure (conscious, nonsedated patients), during procedure (intubated patients), and the first day after MitraClip implantation (conscious, extubated patients). Results. Mitral valve clipping significantly increased cardiac index (CI) (from 2.0 ± 0.5 to 3.3 ± 0.6 L/min/m2; p < 0.01). Conversely, there was significant reduction in the mean pulmonary capillary wedge pressure (PCWP) (from 18.6 ± 5.7 to 10.5 ± 3.8 mmHg; p < 0.01), mean pulmonary artery pressure (from 29.8 ± 10.9 to 25.2 ± 10.3 mmHg; p = 0.03), and pulmonary vascular resistance index (from 531 ± 359 to 365 ± 193 dyn·s·cm−5/m2; p = 0.03). Conclusions. The functional MR therapy with percutaneous MitraClip device results in significant increase in CI (+66%) and concomitant decrease in PCWP (−42%). None of our patients developed low cardiac output state. Our results support the idea that significant part of low cardiac output state after cardiac surgery is due to surgery related factors rather than due to increase in afterload after MR elimination. PMID:28058260

  11. Left ventricular outflow tract velocity time integral outperforms ejection fraction and Doppler-derived cardiac output for predicting outcomes in a select advanced heart failure cohort.

    PubMed

    Tan, Christina; Rubenson, David; Srivastava, Ajay; Mohan, Rajeev; Smith, Michael R; Billick, Kristen; Bardarian, Samuel; Thomas Heywood, J

    2017-07-03

    Left ventricular outflow tract velocity time integral (LVOT VTI) is a measure of cardiac systolic function and cardiac output. Heart failure patients with low cardiac output are known to have poor cardiovascular outcomes. Thus, extremely low LVOT VTI may predict heart failure patients at highest risk for mortality. Patients with heart failure and extremely low LVOT VTI were identified from a single-center database. Baseline characteristics and heart failure related clinical outcomes (death, LVAD) were obtained at 12 months. Correlation between clinical endpoints and the following variables were analyzed: ejection fraction (EF), pulmonary artery systolic pressure (PASP), NYHA class, renal function, Doppler cardiac output (CO), and LVOT VTI. Study cohort consisted of 100 patients. At the 12-month follow up period, 30 events (28 deaths, 2 LVADs) were identified. Occurrence of death and LVAD implantation was statistically associated with a lower LVOT VTI (p = 0.039) but not EF (p = 0.169) or CO (p = 0.217). In multivariate analysis, LVOT VTI (p = 0.003) remained statistically significant, other significant variables were age (p = 0.033) and PASP (p = 0.022). Survival analysis by LVOT VTI tertile demonstrated an unadjusted hazard ratio of 4.755 (CI 1.576-14.348, p = 0.006) for combined LVAD and mortality at one year. Extremely low LVOT VTI strongly predicts adverse outcomes and identifies patients who may benefit most from advanced heart failure therapies.

  12. Blood-Pressure Measuring System Gives Accurate Graphic Output

    NASA Technical Reports Server (NTRS)

    1965-01-01

    The problem: To develop an instrument that will provide an external (indirect) measurement of arterial blood pressure in the form of an easily interpreted graphic trace that can be correlated with standard clinical blood-pressure measurements. From sphygmograms produced by conventional sphygmographs, it is very difficult to differentiate the systolic and diastolic blood-pressure pulses and to correlate these indices with the standard clinical values. It is nearly impossible to determine these indices when the subject is under physical or emotional stress. The solution: An electronic blood-pressure system, basically similar to conventional ausculatory sphygmomanometers, employing a standard occluding cuff, a gas-pressure source, and a gas-pressure regulator and valve. An electrical output transducer senses cuff pressure, and a microphone positioned on the brachial artery under the occluding cuff monitors the Korotkoff sounds from this artery. The output signals present the conventional systolic and diastolic indices in a clear, graphical display. The complete system also includes an electronic timer and cycle-control circuit.

  13. Arterial pressure-based cardiac output monitoring: a multicenter validation of the third-generation software in septic patients.

    PubMed

    De Backer, Daniel; Marx, Gernot; Tan, Andrew; Junker, Christopher; Van Nuffelen, Marc; Hüter, Lars; Ching, Willy; Michard, Frédéric; Vincent, Jean-Louis

    2011-02-01

    Second-generation FloTrac software has been shown to reliably measure cardiac output (CO) in cardiac surgical patients. However, concerns have been raised regarding its accuracy in vasoplegic states. The aim of the present multicenter study was to investigate the accuracy of the third-generation software in patients with sepsis, particularly when total systemic vascular resistance (TSVR) is low. Fifty-eight septic patients were included in this prospective observational study in four university-affiliated ICUs. Reference CO was measured by bolus pulmonary thermodilution (iCO) using 3-5 cold saline boluses. Simultaneously, CO was computed from the arterial pressure curve recorded on a computer using the second-generation (CO(G2)) and third-generation (CO(G3)) FloTrac software. CO was also measured by semi-continuous pulmonary thermodilution (CCO). A total of 401 simultaneous measurements of iCO, CO(G2), CO(G3), and CCO were recorded. The mean (95%CI) biases between CO(G2) and iCO, CO(G3) and iCO, and CCO and iCO were -10 (-15 to -5)% [-0.8 (-1.1 to -0.4) L/min], 0 (-4 to 4)% [0 (-0.3 to 0.3) L/min], and 9 (6-13)% [0.7 (0.5-1.0) L/min], respectively. The percentage errors were 29 (20-37)% for CO(G2), 30 (24-37)% for CO(G3), and 28 (22-34)% for CCO. The difference between iCO and CO(G2) was significantly correlated with TSVR (r(2) = 0.37, p < 0.0001). A very weak (r(2) = 0.05) relationship was also observed for the difference between iCO and CO(G3). In patients with sepsis, the third-generation FloTrac software is more accurate, as precise, and less influenced by TSVR than the second-generation software.

  14. Arterial pressure-based cardiac output monitoring: a multicenter validation of the third-generation software in septic patients

    PubMed Central

    Marx, Gernot; Tan, Andrew; Junker, Christopher; Van Nuffelen, Marc; Hüter, Lars; Ching, Willy; Michard, Frédéric; Vincent, Jean-Louis

    2010-01-01

    Purpose Second-generation FloTrac software has been shown to reliably measure cardiac output (CO) in cardiac surgical patients. However, concerns have been raised regarding its accuracy in vasoplegic states. The aim of the present multicenter study was to investigate the accuracy of the third-generation software in patients with sepsis, particularly when total systemic vascular resistance (TSVR) is low. Methods Fifty-eight septic patients were included in this prospective observational study in four university-affiliated ICUs. Reference CO was measured by bolus pulmonary thermodilution (iCO) using 3–5 cold saline boluses. Simultaneously, CO was computed from the arterial pressure curve recorded on a computer using the second-generation (COG2) and third-generation (COG3) FloTrac software. CO was also measured by semi-continuous pulmonary thermodilution (CCO). Results A total of 401 simultaneous measurements of iCO, COG2, COG3, and CCO were recorded. The mean (95%CI) biases between COG2 and iCO, COG3 and iCO, and CCO and iCO were −10 (−15 to −5)% [−0.8 (−1.1 to −0.4) L/min], 0 (−4 to 4)% [0 (−0.3 to 0.3) L/min], and 9 (6–13)% [0.7 (0.5–1.0) L/min], respectively. The percentage errors were 29 (20–37)% for COG2, 30 (24–37)% for COG3, and 28 (22–34)% for CCO. The difference between iCO and COG2 was significantly correlated with TSVR (r2 = 0.37, p < 0.0001). A very weak (r2 = 0.05) relationship was also observed for the difference between iCO and COG3. Conclusions In patients with sepsis, the third-generation FloTrac software is more accurate, as precise, and less influenced by TSVR than the second-generation software. Electronic supplementary material The online version of this article (doi:10.1007/s00134-010-2098-8) contains supplementary material, which is available to authorized users. PMID:21153399

  15. Continuous minimally invasive cardiac output monitoring with the COstatus in a neonatal swine model: recalibration is necessary during vasoconstriction and vasodilation.

    PubMed

    Cisternas, Alvaro F; Martin-Flores, Manuel; Gleed, Robin D

    2015-08-01

    The COstatus monitor measures cardiac output via the transpulmonary ultrasound dilution method (COTPUD ) after injection of normal saline, and can calculate continuous cardiac output (CCO) from the arterial pressure waveform. The relationship between arterial waveform and COTPUD however, might be degraded during vasoconstriction/vasodilation. To examine if recalibration of arterial waveform-derived CCO is required during mild vasoconstriction/vasodilation. In 10 anesthetized piglets (6.6-10.1 kg), two COstatus monitors calculated the CCO from the same femoral arterial waveform before and during infusions of phenylephrine (PE; 1 or 3 mg·kg(-1) ·min(-1) ) and sodium nitroprusside (SNP; 1 or 5 mg·kg(-1) ·min(-1) ), administered in random order. One monitor was recalibrated (CCORecal ) after each intervention, while the other monitor was not (CCONon-Recal ). Recalibration was performed with COTPUD with 1 ml·kg(-1) normal saline as indicator. The effects of each infusion on hemodynamic parameters were compared with baseline using paired t-tests. The bias, limits of agreement (LOA), and percentage error between simultaneous measurements (CCORecal and CCONon-Recal ) were examined with Bland-Altman plots. Infusion of PE significantly increased COTPUD , heart rate (HR), and arterial pressures but not systemic vascular resistance (SVR). Infusion of SNP decreased arterial pressures without affecting COTPUD , HR, and SVR. There was no bias between CCORecal and CCONon-Recal at the baseline, but a small bias was observed during PE and SNP infusions. The LOA increased approximately 10 fold during vasoconstriction and vasodilation. The percentage error increased from ≤ 5% to 32% and 27% during PE and SNP infusions, respectively. Continuous cardiac output (CO) measured with the COstatus monitor requires recalibration during vasoconstriction and vasodilation, even if changes in COTPUD or SVR are not substantial. © 2015 John Wiley & Sons Ltd.

  16. Cardiac output by Doppler echocardiography in the premature baboon: comparison with radiolabeled microspheres.

    PubMed

    Kinsella, J P; Morrow, W R; Gerstmann, D R; Taylor, A F; deLemos, R A

    1991-04-01

    Pulsed-Doppler echocardiography (PDE) is a useful noninvasive method for determining left ventricular output (LVO). However, despite increasingly widespread use in neonatal intensive care units, validation studies in prematures with cardiopulmonary disease are lacking. The purpose of this study was to compare radiolabeled microsphere (RLM) and PDE measurements of LVO, using the critically ill premature baboon as a model of the human neonate. Twenty-two paired RLM and PDE measurements of LVO were obtained in 14 animals between 3 and 24 h of age. Average PDE LVO was 152 ml/min/kg (range, 40-258 ml/min/kg) compared to 158 ml/min/kg (range, 67-278 ml/min/kg) measured by RLM. Linear regression analysis of the paired measurements showed good correlation with a slope near unity (gamma = 0.94x + 4.20, r = 0.91, SEE = 25.7 ml). We conclude that PDE determinations of LVO compare well with those measured by RLM in the premature baboon. PDE appears to provide a valid estimate of LVO and should be useful in human prematures with cardiopulmonary distress.

  17. Cardiac output by Doppler echocardiography in the premature baboon: Comparison with radiolabeled microspheres

    SciTech Connect

    Kinsella, J.P.; Morrow, W.R.; Gerstmann, D.R.; Taylor, A.F.; deLemos, R.A. )

    1991-04-01

    Pulsed-Doppler echocardiography (PDE) is a useful noninvasive method for determining left ventricular output (LVO). However, despite increasingly widespread use in neonatal intensive care units, validation studies in prematures with cardiopulmonary disease are lacking. The purpose of this study was to compare radiolabeled microsphere (RLM) and PDE measurements of LVO, using the critically ill premature baboon as a model of the human neonate. Twenty-two paired RLM and PDE measurements of LVO were obtained in 14 animals between 3 and 24 h of age. Average PDE LVO was 152 ml/min/kg (range, 40-258 ml/min/kg) compared to 158 ml/min/kg (range, 67-278 ml/min/kg) measured by RLM. Linear regression analysis of the paired measurements showed good correlation with a slope near unity (gamma = 0.94x + 4.20, r = 0.91, SEE = 25.7 ml). The authors conclude that PDE determinations of LVO compare well with those measured by RLM in the premature baboon. PDE appears to provide a valid estimate of LVO and should be useful in human prematures with cardiopulmonary distress.

  18. Effect of hemorrhage on cardiac output, vasopressin, aldosterone, and diuresis during immersion in men

    NASA Technical Reports Server (NTRS)

    Greenleaf, J. E.; Simanonok, K.; Bernauer, E. M.; Wade, C. E.; Keil, L. C.

    1992-01-01

    The purpose of this research was to test the hypotesis that a reduction in blood volume would attenuate or eliminate immersion-induced increases in cardiac output (Q(sub co)) and urine excretion, and to investigate accompanying vasoactive and fluid-electrolyte hormonal responses. Eight men (19-23 yr) were supine during a 2-hr control period in air, and then sat for 5-hr test periods in air at 20 C (dry control, DC); water at 34.5 C (wet control, WC); and water (34.5 C) after hemorrhage (WH) of 14.8 plus or minus 0.3 percent of their blood volume. Blood volume was -11.6 plus or minus 0.6 percent at immersion (time 0). Mean (bar-X hrs 1-5) Q(sub co) was unchanged in WC (5.3 plus or minus 0.01 l/min) and in WH (4.5 plus or minus 0.1 l/min), but decreased (P less than 0.05) in DC to 3.6 plus or minus 0.1 l/min. Mean urine excretion rates were 1.0 plus or minus 0.2 ml/min for DC and 1.1 plus or minus 0.2 ml/min for WH; both were lower (P less than 0.05) than that for WC of 2.0 plus or minus 0.4 ml/min. Plasma (Na+) and (Osm) were unchanged in all experiments. Mean plasma vasopressin (PVP) (bar-X hrs 1-5) was 1.1 plus or minus 0.1 pg/ml in WC, and higher (P less than 0.05) in DC (2.1 plus or minus 0.2 pg/ml)and WH (2.1 plus or minus 0.1 pg/ml); it was unchanged during air and water test periods. Thus, hemorrhage attenuated the immersion-induced increase in Q(sub co), eliminated the WC diuresis, maintained plasma renin activity and PVP at DC levels and did not change immersion-induced aldosterone suppression; the osmotic diuresis during control immersion is apparently not due to either aldosterone suppression or vasopressin suppression.

  19. Cardiac Output Monitoring Managing Intravenous Therapy (COMMIT) to Treat Emergency Department Patients with Sepsis

    PubMed Central

    Hou, Peter C.; Filbin, Michael R.; Napoli, Anthony; Feldman, Joseph; Pang, Peter S.; Sankoff, Jeffrey; Lo, Bruce M.; Dickey-White, Howard; Birkhahn, Robert H.; Shapiro, Nathan I.

    2016-01-01

    ABSTRACT Objective: Fluid responsiveness is proposed as a physiology-based method to titrate fluid therapy based on preload dependence. The objectives of this study were to determine if a fluid responsiveness protocol would decrease progression of organ dysfunction, and a fluid responsiveness protocol would facilitate a more aggressive resuscitation. Methods: Prospective, 10-center, randomized interventional trial. Inclusion criteria: suspected sepsis and lactate 2.0 to 4.0 mmol/L. Exclusion criteria (abbreviated): systolic blood pressure more than 90 mmHg, and contraindication to aggressive fluid resuscitation. Intervention: fluid responsiveness protocol using Non-Invasive Cardiac Output Monitor (NICOM) to assess for fluid responsiveness (>10% increase in stroke volume in response to 5 mL/kg fluid bolus) with balance of a liter given in responsive patients. Control: standard clinical care. Outcomes: primary—change in Sepsis-related Organ Failure Assessment (SOFA) score at least 1 over 72 h; secondary—fluids administered. Trial was initially powered at 600 patients, but stopped early due to a change in sponsor's funding priorities. Results: Sixty-four patients were enrolled with 32 in the treatment arm. There were no significant differences between arms in age, comorbidities, baseline vital signs, or SOFA scores (P > 0.05 for all). Comparing treatment versus Standard of Care—there was no difference in proportion of increase in SOFA score of at least 1 point (30% vs. 33%) (note bene underpowered, P = 1.0) or mean preprotocol fluids 1,050 mL (95% confidence interval [CI]: 786–1,314) vs. 1,031 mL (95% CI: 741–1,325) (P = 0.93); however, treatment patients received more fluids during the protocol (2,633 mL [95% CI: 2,264–3,001] vs. 1,002 mL [95% CI: 707–1,298]) (P < 0.001). Conclusions: In this study of a “preshock” population, there was no change in progression of organ dysfunction with a fluid responsiveness protocol

  20. Blood pressure reduction after gastric bypass surgery is explained by a decrease in cardiac output.

    PubMed

    van Brussel, Peter M; van den Bogaard, Bas; de Weijer, Barbara A; Truijen, Jasper; Krediet, C T Paul; Janssen, Ignace M; van de Laar, Arnold; Kaasjager, Karin; Fliers, Eric; van Lieshout, Johannes J; Serlie, Mireille J; van den Born, Bert-Jan H

    2017-02-01

    Blood pressure (BP) decreases in the first weeks after Roux-and-Y gastric bypass surgery. Yet the pathophysiology of the BP-lowering effects observed after gastric bypass surgery is incompletely understood. We evaluated BP, systemic hemodynamics, and baroreflex sensitivity in 15 obese women[mean age 42 ± 7 standard deviation (SD) yr, body mass index 45 ± 6 kg/m(2)] 2 wk before and 6 wk following Roux-and-Y gastric bypass surgery. Six weeks after gastric bypass surgery, mean body weight decreased by 13 ± 5 kg (10%, P < 0.001). Office BP decreased from 137 ± 10/86 ± 6 to 128 ± 12/81 ± 9 mmHg (P < 0.001, P < 0.01), while daytime ambulatory BP decreased from 128 ± 14/80 ± 9 to 114 ± 10/73 ± 6 mmHg (P = 0.01, P = 0.05), whereas nighttime BP decreased from 111 ± 13/66 ± 7 to 102 ± 9/62 ± 7 mmHg (P = 0.04, P < 0.01). The decrease in BP was associated with a 1.6 ± 1.2 l/min (20%, P < 0.01) decrease in cardiac output (CO), while systemic vascular resistance increased (153 ± 189 dyn·s·cm(-5), 15%, P < 0.01). The maximal ascending slope in systolic blood pressure decreased (192 mmHg/s, 19%, P = 0.01), suggesting a reduction in left ventricular contractility. Baroreflex sensitivity increased from 9.0 [6.4-14.3] to 13.8 [8.5-19.0] ms/mmHg (median [interquartile range]; P < 0.01) and was inversely correlated with the reductions in heart rate (R = -0.64, P = 0.02) and CO (R = -0.61, P = 0.03). In contrast, changes in body weight were not correlated with changes in either BP or CO. The BP reduction following Roux-and-Y gastric bypass surgery is correlated with a decrease in CO independent of changes in body weight. The contribution of heart rate to the reduction in CO together with enhanced baroreflex sensitivity suggests a shift toward increased parasympathetic cardiovascular control.

  1. Scalp congenital hemangioma with associated high-output cardiac failure in a premature infant: Case report and review of literature.

    PubMed

    Shah, Sumedh S; Snelling, Brian M; Sur, Samir; Ramnath, Alexandra R; Bandstra, Emmalee S; Yavagal, Dileep R

    2017-02-01

    Introduction Scalp congenital hemangiomas (CHs) are rare vascular malformations among infants; they can be associated with an array of complications, including cardiac and cosmetic issues. Here, we report the endovascular treatment of a premature infant with a suspected large right parietal scalp hemangioma and associated high-output cardiac failure. Case description A two-day-old female premature infant (29 weeks gestational age; 1330 g birth weight) was referred by the neonatologists to our department for consultation and potential treatment of a large right parietal CH causing abrupt hypotension and high-output cardiac failure. Doppler ultrasound imaging at bedside revealed areas of arterial-venous shunting from the scalp and the presence of a superior sagittal sinus waveform, consistent with intracranial venous drainage. To alleviate cardiac dysfunction secondary to this lesion, trans-arterial embolization via n-butyl cyanoacrylate (nBCA) glue and deployment of detachable coils was performed via umbilical artery to occlude the right superficial temporal and occipital artery branches supplying the CH. Following treatment, the infant continued to require ventilator management, vasopressor support, and correction of coagulopathy, but by post-operative day two, her condition improved remarkably and the mass size began decreasing. The patient was discharged after a relatively uncomplicated subsequent 2½-month course in the neonatal intensive care unit. Conclusion Endovascular therapy proved effective and safe in treating cardiac failure associated with scalp CH, despite potential complications associated with neuro-interventional surgery in premature infants. Appropriate consideration in this patient population should be given to factors including blood loss, contrast use, radiation exposure, operative time, and possible intra-/post-operative complications.

  2. Blunted frequency-dependent upregulation of cardiac output is related to impaired relaxation in diastolic heart failure

    PubMed Central

    Wachter, Rolf; Schmidt-Schweda, Stephan; Westermann, Dirk; Post, Heiner; Edelmann, Frank; Kasner, Mario; Lüers, Claus; Steendijk, Paul; Hasenfuß, Gerd; Tschöpe, Carsten; Pieske, Burkert

    2009-01-01

    Aims We tested the hypothesis that, in heart failure with normal ejection fraction (HFNEF), diastolic dysfunction is accentuated at increasing heart rates, and this contributes to impaired frequency-dependent augmentation of cardiac output. Methods and results In 17 patients with HFNEF (median age 69 years, 13 female) and seven age-matched control patients, systolic and diastolic function was analysed by pressure–volume loops at baseline heart rate and during atrial pacing to 100 and 120 min−1. At baseline, relaxation was prolonged and end-diastolic left ventricular stiffness was higher in HFNEF, whereas all parameters of systolic function were not different from control patients. This resulted in smaller end-diastolic volumes, higher end-diastolic pressure, and a lower stroke volume and cardiac index in HFNEF vs. control patients. During pacing, frequency-dependent upregulation of contractility indices (+dP/dtmax and Ees) occurred similarly in HFNEF and control patients, but frequency-dependent acceleration of relaxation (dP/dtmin) was blunted in HFNEF. In HFNEF, end-diastolic volume and stroke volume decreased with higher heart rates while both remained unchanged in control patients. Conclusion In HFNEF, frequency-dependent upregulation of cardiac output is blunted. This results from progressive volume unloading of the left ventricle due to limited relaxation reserve in combination with increased LV passive stiffness, despite preserved force–frequency relation. PMID:19720638

  3. Blunted frequency-dependent upregulation of cardiac output is related to impaired relaxation in diastolic heart failure.

    PubMed

    Wachter, Rolf; Schmidt-Schweda, Stephan; Westermann, Dirk; Post, Heiner; Edelmann, Frank; Kasner, Mario; Lüers, Claus; Steendijk, Paul; Hasenfuss, Gerd; Tschöpe, Carsten; Pieske, Burkert

    2009-12-01

    We tested the hypothesis that, in heart failure with normal ejection fraction (HFNEF), diastolic dysfunction is accentuated at increasing heart rates, and this contributes to impaired frequency-dependent augmentation of cardiac output. In 17 patients with HFNEF (median age 69 years, 13 female) and seven age-matched control patients, systolic and diastolic function was analysed by pressure-volume loops at baseline heart rate and during atrial pacing to 100 and 120 min(-1). At baseline, relaxation was prolonged and end-diastolic left ventricular stiffness was higher in HFNEF, whereas all parameters of systolic function were not different from control patients. This resulted in smaller end-diastolic volumes, higher end-diastolic pressure, and a lower stroke volume and cardiac index in HFNEF vs. control patients. During pacing, frequency-dependent upregulation of contractility indices (+dP/dt(max) and Ees) occurred similarly in HFNEF and control patients, but frequency-dependent acceleration of relaxation (dP/dt(min)) was blunted in HFNEF. In HFNEF, end-diastolic volume and stroke volume decreased with higher heart rates while both remained unchanged in control patients. In HFNEF, frequency-dependent upregulation of cardiac output is blunted. This results from progressive volume unloading of the left ventricle due to limited relaxation reserve in combination with increased LV passive stiffness, despite preserved force-frequency relation.

  4. Effects of hypertrophic and dilated cardiomyopathy mutations on power output by human β-cardiac myosin.

    PubMed

    Spudich, James A; Aksel, Tural; Bartholomew, Sadie R; Nag, Suman; Kawana, Masataka; Yu, Elizabeth Choe; Sarkar, Saswata S; Sung, Jongmin; Sommese, Ruth F; Sutton, Shirley; Cho, Carol; Adhikari, Arjun S; Taylor, Rebecca; Liu, Chao; Trivedi, Darshan; Ruppel, Kathleen M

    2016-01-01

    Hypertrophic cardiomyopathy is the most frequently occurring inherited cardiovascular disease, with a prevalence of more than one in 500 individuals worldwide. Genetically acquired dilated cardiomyopathy is a related disease that is less prevalent. Both are caused by mutations in the genes encoding the fundamental force-generating protein machinery of the cardiac muscle sarcomere, including human β-cardiac myosin, the motor protein that powers ventricular contraction. Despite numerous studies, most performed with non-human or non-cardiac myosin, there is no clear consensus about the mechanism of action of these mutations on the function of human β-cardiac myosin. We are using a recombinantly expressed human β-cardiac myosin motor domain along with conventional and new methodologies to characterize the forces and velocities of the mutant myosins compared with wild type. Our studies are extending beyond myosin interactions with pure actin filaments to include the interaction of myosin with regulated actin filaments containing tropomyosin and troponin, the roles of regulatory light chain phosphorylation on the functions of the system, and the possible roles of myosin binding protein-C and titin, important regulatory components of both cardiac and skeletal muscles.

  5. Accuracy and precision of minimally-invasive cardiac output monitoring in children: a systematic review and meta-analysis.

    PubMed

    Suehiro, Koichi; Joosten, Alexandre; Murphy, Linda Suk-Ling; Desebbe, Olivier; Alexander, Brenton; Kim, Sang-Hyun; Cannesson, Maxime

    2016-10-01

    Several minimally-invasive technologies are available for cardiac output (CO) measurement in children, but the accuracy and precision of these devices have not yet been evaluated in a systematic review and meta-analysis. We conducted a comprehensive search of the medical literature in PubMed, Cochrane Library of Clinical Trials, Scopus, and Web of Science from its inception to June 2014 assessing the accuracy and precision of all minimally-invasive CO monitoring systems used in children when compared with CO monitoring reference methods. Pooled mean bias, standard deviation, and mean percentage error of included studies were calculated using a random-effects model. The inter-study heterogeneity was also assessed using an I(2) statistic. A total of 20 studies (624 patients) were included. The overall random-effects pooled bias, and mean percentage error were 0.13 ± 0.44 l min(-1) and 29.1 %, respectively. Significant inter-study heterogeneity was detected (P < 0.0001, I(2) = 98.3 %). In the sub-analysis regarding the device, electrical cardiometry showed the smallest bias (-0.03 l min(-1)) and lowest percentage error (23.6 %). Significant residual heterogeneity remained after conducting sensitivity and subgroup analyses based on the various study characteristics. By meta-regression analysis, we found no independent effects of study characteristics on weighted mean difference between reference and tested methods. Although the pooled bias was small, the mean pooled percentage error was in the gray zone of clinical applicability. In the sub-group analysis, electrical cardiometry was the device that provided the most accurate measurement. However, a high heterogeneity between studies was found, likely due to a wide range of study characteristics.

  6. Measuring nebulizer output. Aerosol production vs gravimetric analysis.

    PubMed

    Tandon, R; McPeck, M; Smaldone, G C

    1997-05-01

    The function of jet nebulizers has been measured traditionally by gravimetric methods, i.e., by weighing nebulizers before and after nebulization. Newer techniques measure aerosol output directly by analyzing aerosolized drug or tracer, i.e., radioactive 99mTc. Because of evaporation, the equivalence of these methods is uncertain. The aim of this study was to determine if the gravimetric method is an accurate measure of aerosol production under different conditions of aerosol generation (i.e., nebulizer type, flow rate, pressure, volume fill, and concentration of solution used to nebulize a drug). In the first phase of the study, we measured the aerosol output of nine commercially available jet nebulizers (AvaNeb; Up-Draft-Hudson RCI; Cirrus-Intersurgical Inc; DeVilbiss 646-DeVilbiss; Powermist-Hospitak, Inc; Respirgard II-Marquest Medical Products; Seamless-Seamless/Dart Respiratory; Salter; Salter Labs; Airlife-Baxter Health Care) run under commonly used conditions (2.5 mL volume fill, 2.0 mL normal saline solvent, 0.5 mL albuterol, flow of 6 L/min, and pressures averaging 15.0 +/- 2.3 [mean +/- SD] pounds per square inch [on the] gauge [psig] provided by a DeVilbiss PulmoAide compressor) with simultaneously measured gravimetrics and filtered radioactivity. Each nebulizer was run to dryness with data acquired every 2 min. The change in the weight of the nebulizer and radioactivity captured on the filter were expressed as percentages of the total in the nebulizer solution. In the second phase of the study, the experiments were repeated using the same nebulizers with a volume fill of 5 mL (diluted to half normal saline solution plus albuterol), flow of 10 L/min, and pressures of 35.6 +/- 8.8 psig. The cumulative (sum of all 2-min runs) weight loss for each individual nebulizer ranged from 25.00 to 64.55% and cumulative aerosol captured varied from 12.63 to 38.76%. While different, the weight loss and aerosol captured were closely correlated (y = -0.62 + 0.62x; r

  7. Glucagon-like peptide-1 (7-36) but not (9-36) augments cardiac output during myocardial ischemia via a Frank-Starling mechanism.

    PubMed

    Goodwill, Adam G; Tune, Johnathan D; Noblet, Jillian N; Conteh, Abass M; Sassoon, Daniel; Casalini, Eli D; Mather, Kieren J

    2014-01-01

    This study examined the cardiovascular effects of GLP-1 (7-36) or (9-36) on myocardial oxygen consumption, function and systemic hemodynamics in vivo during normal perfusion and during acute, regional myocardial ischemia. Lean Ossabaw swine received systemic infusions of saline vehicle or GLP-1 (7-36 or 9-36) at 1.5, 3.0, and 10.0 pmol/kg/min in sequence for 30 min at each dose, followed by ligation of the left circumflex artery during continued infusion at 10.0 pmol/kg/min. Systemic GLP-1 (9-36) had no effect on coronary flow, blood pressure, heart rate or indices of cardiac function before or during regional myocardial ischemia. Systemic GLP-1 (7-36) exerted no cardiometabolic or hemodynamic effects prior to ischemia. During ischemia, GLP-1 (7-36) increased cardiac output by approximately 2 L/min relative to vehicle-controls (p = 0.003). This response was not diminished by treatment with the non-depolarizing ganglionic blocker hexamethonium. Left ventricular pressure-volume loops measured during steady-state conditions with graded occlusion of the inferior vena cava to assess load-independent contractility revealed that GLP-1 (7-36) produced marked increases in end-diastolic volume (74 ± 1 to 92 ± 5 ml; p = 0.03) and volume axis intercept (8 ± 2 to 26 ± 8; p = 0.05), without any change in the slope of the end-systolic pressure-volume relationship vs. vehicle during regional ischemia. GLP-1 (9-36) produced no changes in any of these parameters compared to vehicle. These findings indicate that short-term systemic treatment with GLP-1 (7-36) but not GLP-1 (9-36) significantly augments cardiac output during regional myocardial ischemia, via increases in ventricular preload without changes in cardiac inotropy.

  8. Protection of the ischaemic myocardium by L-propionylcarnitine: effects on the recovery of cardiac output after ischaemia and reperfusion, carnitine transport, and fatty acid oxidation.

    PubMed

    Paulson, D J; Traxler, J; Schmidt, M; Noonan, J; Shug, A L

    1986-07-01

    The effects of L-propionylcarnitine on the recovery of cardiac contractile performance after global ischaemia and reperfusion were studied in isolated perfused rat hearts. The addition of either 5.5 or 11 mmol X litre-1 L-propionylcarnitine significantly improved the recovery of cardiac output, left ventricular pressure, and dP/dt after 90 min of ischaemia and 15 min of reperfusion. Myocardial adenosine triphosphate and creatine phosphate concentrations were significantly higher in the L-propionylcarnitine treated hearts than in controls, but the concentrations of long chain acyl carnitine and coenzyme A were unaffected. The protecting effects of L-propionylcarnitine were compared with those of L-carnitine and L-acetylcarnitine. A 11 mmol X litre-1 dose of L-propionylcarnitine and L-acetylcarnitine significantly improved the recovery of cardiac output after 90 min of ischaemia and 15 min of reperfusion, but L-carnitine did not. L-Propionylcarnitine was the most protective agent. The effects of these derivatives on L-3H-carnitine transport and 14C-palmitate oxidation were also measured. All of these derivatives competitively inhibited L-3H-carnitine transport in isolated cardiac myocytes, but L-propionylcarnitine was the most potent. Carnitine and L-propionylcarnitine stimulated palmitate oxidation in the homogenate, whereas L-acetylcarnitine inhibited it. In myocytes only L-propionylcarnitine affected palmitate oxidation. These data show that L-propionylcarnitine protects the ischaemic myocardium. Its protection is greater than that for L-carnitine or L-acetylcarnitine, and the difference in effectiveness may relate to the rate of transport into the cells and the effects on fatty acid utilisation.

  9. Noninvasive cardiac output monitoring during exercise testing: Nexfin pulse contour analysis compared to an inert gas rebreathing method and respired gas analysis.

    PubMed

    Bartels, Sebastiaan A; Stok, Wim J; Bezemer, Rick; Boksem, Remco J; van Goudoever, Jeroen; Cherpanath, Thomas G V; van Lieshout, Johannes J; Westerhof, Berend E; Karemaker, John M; Ince, Can

    2011-10-01

    Exercise testing is often used to assess cardiac function during physical exertion to obtain diagnostic information. However, this procedure is limited to measuring the electrical activity of the heart using electrocardiography and intermittent blood pressure (BP) measurements and does not involve the continuous assessment of heart functioning. In this study, we compared continuous beat-to-beat pulse contour analysis to monitor noninvasive cardiac output (CO) during exercise with inert gas rebreathing and respired gas analysis. Nineteen healthy male volunteers were subjected to bicycle ergometry testing with increasing workloads. Cardiac output was deter- mined noninvasively by continuous beat-to-beat pulse contour analysis (Nexfin) and by inert gas rebreathing, and estimated using the respired gas analysis method. The effects of the rebreathing maneuver on heart rate (HR), stroke volume (SV), and CO were evaluated. The CO values derived from the Nexfin- and inert gas rebreathing methods were well correlated (r = 0.88, P < 0.01) and the limits of agreement were 30.3% with a measurement bias of 0.4 ± 1.8 L/min. Nexfin- and respired gas analysis-derived CO values correlated even better (r = 0.94, P < 0.01) and the limits of agreement were 21.5% with a measurement bias of -0.70 ± 1.6 L/min. At rest, the rebreathing maneuver increased HR by 13 beats/min (P < 0.01), SV remained unaffected (P = 0.7), while CO increased by 1.0 L/min (P < 0.01). Rebreathing did not affect these parameters during exercise. Nexfin continuous beat-to-beat pulse contour analysis is an appropriate method for noninvasive assessment of CO during exercise.

  10. Noninvasive assessment of cardiac output from arterial pressure profiles during exercise.

    PubMed

    Antonutto, G; Girardis, M; Tuniz, D; di Prampero, P E

    1995-01-01

    , MAPin, HR, PP, MAP are the above parameters at rest and during exercise, respectively. Also in this case, the coefficients f to 1 were determined by a computerized statistical method using Z* as the experimental reference. The values of Zcor so obtained allowed us to calculate SV from arterial pulse contour analysis as SVF = As.Z-1cor. The mean percentage error between the SVF obtained and the values simultaneously determined by PDE, was 10.0 (SD 8.7)%. It is concluded that the SV of the left ventricle, and hence cardiac output, can be determined during exercise from photoplethysmograph tracings with reasonable accuracy, provided that an initial estimate of SV at rest is made by means an independent high quality reference method.

  11. Evaluation of TAPSE as a measure of right ventricular output.

    PubMed

    Tousignant, Claude; Kim, Han; Papa, Fabio; Mazer, C David

    2012-04-01

    This study was designed to show the relationship between tricuspid annular plane systolic excursion (TAPSE) and stroke volume (SV) by thermodilution using three different methods and also to assess whether TAPSE can track hemodynamic changes associated with volume loading and ephedrine administration. This was an observational study in 61 elective patients with a pulmonary artery catheter who were undergoing coronary artery bypass graft surgery in a cardiac surgical centre. We measured TAPSE by three methods using transesophageal echocardiography: M mode, speckle tracking at the lateral wall, and tissue tracking at the inferior wall. There were two interventions: leg raising (volume recruitment) or administration of ephedrine 5 mg iv. Echo and hemodynamic measurements were performed before and after each intervention. Eleven patients were excluded due to poor imaging. There were 26 patients in the leg raising group and 24 patients in the ephedrine group. The correlation coefficient between stroke volume (SV) and TAPSE by M mode, speckle tracking, and tissue tracking was 0.48, 0.44, and 0.09, respectively. There was a significant increase in SV following each intervention; however, the changes in TAPSE by any method and velocity were not large enough to reach statistical significance. Tricuspid annular plane systolic excursion by M mode and by speckle tracking correlates modestly with SV. There was no correlation between TAPSE and SV by tissue tracking at the inferior wall of the right ventricle. Tricuspid annular plane systolic excursion by M mode and by speckle tracking does not track changes in SV following either volume loading or ephedrine administration.

  12. Low cardiac output syndrome in the postoperative period of cardiac surgery. Profile, differences in clinical course and prognosis. The ESBAGA study.

    PubMed

    Pérez Vela, J L; Jiménez Rivera, J J; Alcalá Llorente, M Á; González de Marcos, B; Torrado, H; García Laborda, C; Fernández Zamora, M D; González Fernández, F J; Martín Benítez, J C

    2017-07-20

    An analysis is made of the clinical profile, evolution and differences in morbidity and mortality of low cardiac output syndrome (LCOS) in the postoperative period of cardiac surgery, according to the 3 diagnostic subgroups defined by the SEMICYUC Consensus 2012. A multicenter, prospective cohort study was carried out. ICUs of Spanish hospitals with cardiac surgery. A consecutive sample of 2,070 cardiac surgery patients was included, with the analysis of 137 patients with LCOS. No intervention was carried out. The mean patient age was 68.3±9.3 years (65.2% males), with a EuroSCORE II of 9.99±13. NYHA functional class III-IV (52.9%), left ventricular ejection fraction<35% (33.6%), AMI (31.9%), severe PHT (21.7%), critical preoperative condition (18.8%), prior cardiac surgery (18.1%), PTCA/stent placement (16.7%). According to subgroups, 46 patients fulfilled hemodynamic criteria of LCOS (group A), 50 clinical criteria (group B), and the rest (n=41) presented cardiogenic shock (group C). Significant differences were observed over the evolutive course between the subgroups in terms of time subjected to mechanical ventilation (114.4, 135.4 and 180.3min in groups A, B and C, respectively; P<.001), renal replacement requirements (11.4, 14.6 and 36.6%; P=.007), multiorgan failure (16.7, 13 and 47.5%), and mortality (13.6, 12.5 and 35.9%; P=.01). The mean maximum lactate concentration was higher in cardiogenic shock patients (P=.002). The clinical evolution of these patients leads to high morbidity and mortality. We found differences between the subgroups in terms of the postoperative clinical course and mortality. Copyright © 2017 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

  13. Reduced central blood volume and cardiac output and increased vascular resistance during static handgrip exercise in postural tachycardia syndrome.

    PubMed

    Stewart, Julian M; Taneja, Indu; Medow, Marvin S

    2007-09-01

    Postural tachycardia syndrome (POTS) is characterized by exercise intolerance and sympathoactivation. To examine whether abnormal cardiac output and central blood volume changes occur during exercise in POTS, we studied 29 patients with POTS (17-29 yr) and 12 healthy subjects (18-27 yr) using impedance and venous occlusion plethysmography to assess regional blood volumes and flows during supine static handgrip to evoke the exercise pressor reflex. POTS was subgrouped into normal and low-flow groups based on calf blood flow. We examined autonomic effects with variability techniques. During handgrip, systolic blood pressure increased from 112 +/- 4 to 139 +/- 9 mmHg in control, from 119 +/- 6 to 143 +/- 9 in normal-flow POTS, but only from 117 +/- 4 to 128 +/- 6 in low-flow POTS. Heart rate increased from 63 +/- 6 to 82 +/- 4 beats/min in control, 76 +/- 3 to 92 +/- 6 beats/min in normal-flow POTS, and 88 +/- 4 to 100 +/- 6 beats/min in low-flow POTS. Heart rate variability and coherence markedly decreased in low-flow POTS, indicating uncoupling of baroreflex heart rate regulation. The increase in central blood volume with handgrip was absent in low-flow POTS and blunted in normal-flow POTS associated with abnormal splanchnic emptying. Cardiac output increased in control, was unchanged in low-flow POTS, and was attenuated in normal-flow POTS. Total peripheral resistance was increased compared with control in all POTS. The exercise pressor reflex was attenuated in low-flow POTS. While increased cardiac output and central blood volume characterizes controls, increased peripheral resistance with blunted or eliminated in central blood volume increments characterizes POTS and may contribute to exercise intolerance.

  14. The thick left ventricular wall of the giraffe heart normalises wall tension, but limits stroke volume and cardiac output.

    PubMed

    Smerup, Morten; Damkjær, Mads; Brøndum, Emil; Baandrup, Ulrik T; Kristiansen, Steen Buus; Nygaard, Hans; Funder, Jonas; Aalkjær, Christian; Sauer, Cathrine; Buchanan, Rasmus; Bertelsen, Mads Frost; Østergaard, Kristine; Grøndahl, Carsten; Candy, Geoffrey; Hasenkam, J Michael; Secher, Niels H; Bie, Peter; Wang, Tobias

    2016-02-01

    Giraffes--the tallest extant animals on Earth--are renowned for their high central arterial blood pressure, which is necessary to secure brain perfusion. Arterial pressure may exceed 300 mmHg and has historically been attributed to an exceptionally large heart. Recently, this has been refuted by several studies demonstrating that the mass of giraffe heart is similar to that of other mammals when expressed relative to body mass. It thus remains unexplained how the normal-sized giraffe heart generates such massive arterial pressures. We hypothesized that giraffe hearts have a small intraventricular cavity and a relatively thick ventricular wall, allowing for generation of high arterial pressures at normal left ventricular wall tension. In nine anaesthetized giraffes (495±38 kg), we determined in vivo ventricular dimensions using echocardiography along with intraventricular and aortic pressures to calculate left ventricular wall stress. Cardiac output was also determined by inert gas rebreathing to provide an additional and independent estimate of stroke volume. Echocardiography and inert gas-rebreathing yielded similar cardiac outputs of 16.1±2.5 and 16.4±1.4 l min(-1), respectively. End-diastolic and end-systolic volumes were 521±61 ml and 228±42 ml, respectively, yielding an ejection fraction of 56±4% and a stroke volume of 0.59 ml kg(-1). Left ventricular circumferential wall stress was 7.83±1.76 kPa. We conclude that, relative to body mass, a small left ventricular cavity and a low stroke volume characterizes the giraffe heart. The adaptations result in typical mammalian left ventricular wall tensions, but produce a lowered cardiac output.

  15. A comparison of the non-invasive ultrasonic cardiac output monitor (USCOM) with the oesophageal Doppler monitor during major abdominal surgery

    PubMed Central

    Forni, Lui G; Venn, Richard; Samuels, Theophilus L; Wakeling, Howard G

    2015-01-01

    Background Perioperative interventions, targeted to increase global blood flow defined by explicit measured goals, reduce postoperative complications. Consequently, reliable non-invasive estimation of the cardiac output could have far-reaching benefit. Methods This study compared a non-invasive Doppler device – the ultrasonic cardiac output monitor (USCOM) – with the oesophageal Doppler monitor (ODM), on 25 patients during major abdominal surgery. Stroke volume was determined by USCOM (SVUSCOM) and ODM (SVODM) pre and post fluid challenges. Results A ≥ 10% change (Δ) SVUSCOM had a sensitivity of 94% and specificity of 88% to detect a ≥ 10% Δ SVODM; the area under the receiver operating curve was 0.94 (95% CI 0.90–0.99). Concordance was 98%, using an exclusion zone of <10% Δ SVODM. 135 measurements gave median SVUSCOM 80 ml (interquartile range 65–93 ml) and SVODM 86 ml (69–100 ml); mean bias was 5.9 ml (limits of agreement −20 to +30 ml) and percentage error 30%. Conclusions Following fluid challenges SVUSCOM showed good concordance and accurately discriminated a change ≥10% in SVODM. PMID:28979473

  16. A minimally invasive monitoring system of cardiac output using aortic flow velocity and peripheral arterial pressure profile.

    PubMed

    Uemura, Kazunori; Kawada, Toru; Inagaki, Masashi; Sugimachi, Masaru

    2013-05-01

    In managing patients with unstable hemodynamics, monitoring cardiac output (CO) can provide critical diagnostic data. However, conventional CO measurements are invasive, intermittent, and/or inaccurate. The purpose of this study was to validate our newly developed CO monitoring system. This system automatically determines peak velocity of the ascending aortic flow using continuous-wave Doppler transthoracic echocardiography and estimates cardiac ejection time and aortic cross-sectional area using the pulse contour of the radial arterial pressure. These parameters are continuously processed to estimate CO (CO(est)). In 10 anesthetized closed-chest dogs instrumented with an aortic flowprobe to measure reference CO (CO(ref)), hemodynamic conditions were varied over wide ranges by infusing cardiovascular drugs or by random atrial pacing. Under each condition, CO(ref) and CO(est) were determined. Absolute changes of CO(ref) (ΔCOref) and CO(est) (ΔCO(est)), and relative changes of CO(ref) (%ΔCO(ref)) and CO(est) (%ΔCO(est)) from the corresponding baseline values were determined in each animal. We calibrated CO(est) against CO(ref) to obtain proportionally scaled CO(est) (CO(est)(N)). A total of 1335 datasets of CO(ref) and CO(est) were obtained, in which CO(ref) ranged from 0.17 to 5.34 L/min. Bland-Altman analysis between CO(ref) and CO(est) indicated that the limits of agreement (the bias ± 1.96 × SD of the difference) and the percentage error (1.96 × [SD of the difference]/[mean CO] × 100) were from -1.01 to 1.13 L/min (95% confidence interval, -1.76 to 1.88 L/min) and 43%, respectively. The agreement between CO(ref) and CO(est)(N) was improved, with limits of agreement from -0.53 to 0.49 L/min (95% confidence interval, -0.62 to 0.59 L/min) and the percentage error of 20%. Polar plot analysis between ΔCO(ref) and ΔCO(est) indicated that mean ± 1.96 × SD of polar angle was -2° ± 22°. Four quadrant plot analysis indicated that %ΔCO(est) correlated

  17. Rest and exercise cardiac output and diffusing capacity assessed by a single slow exhalation of methane, acetylene, and carbon monoxide.

    PubMed

    Ramage, J E; Coleman, R E; MacIntyre, N R

    1987-07-01

    To study rest and exercise pulmonary capillary blood flow (Qc) and diffusing capacity (DLexh) assessed by the rapid analysis of methane, acetylene, and carbon monoxide during a single, slow exhalation, we evaluated 36 subjects during first-pass radionuclide angiography (RNA). At rest (N = 36) and at exercise (N = 21) there was no difference in the respective measurements of cardiac output (Qc = 6.0 +/- 1.7 and CORNA = 6.9 +/- 2.5 at rest; Qc = 13.7 +/- 3.2 and CORNA = 14.5 +/- 4.1 at exercise, L/min, mean +/- SD, r = .80). Mild maldistribution of ventilation, as manifested by an increased phase 3 alveolar slope for methane (CH4 slope), did not significantly influence the results. CH4 slope and DLexh did increase significantly with exercise, while total lung capacity remained unchanged (CH4 slope: 6.2 +/- 5.0 vs 12.5 +/- 6.8% delta CH4/L, mean +/- SD, p less than 0.001; Dsb: 27.7 +/- 9.2 vs 42.0 +/- 17.9 ml/min/mm Hg, mean +/- SD, p less than 0.001; TLC: 5.47 +/- .20 vs 5.96 +/- 1.20 L, mean +/- SD). DLexh was related to CORNA (r = .68) and RNA stroke volume (r = .50). Qc was significantly less than CORNA in the subset of studies with valvular regurgitation (VHD) (N = 7). On the other hand, Qc was significantly greater than CORNA in the setting of coronary artery disease (CAD) and severe wall motion abnormalities (N = 7). These differences may be attributed to regurgitant fractions in VHD, and the influence of wall motion abnormalities on the estimation of left ventricular volume by the area-length method in CAD. These two noninvasive methods compare well at rest and exercise in clinical subjects and may provide complementary information in certain cardiopulmonary diseases.

  18. Combined use of phenoxybenzamine and dopamine for low cardiac output syndrome in children at withdrawal from cardiopulmonary bypass.

    PubMed

    Kawamura, M; Minamikawa, O; Yokochi, H; Maki, S; Yasuda, T; Mizukawa, Y

    1980-04-01

    The combined use of phenoxybenzamine and dopamine was applied in infants and children when it was difficult to come off cardiopulmonary bypass for low cardiac output. The rationale of this method is to prevent the alpha-adrenergic action of dopamine by phenoxybenzamine and to encourage the beta-adrenergic and direct specific action of dopamine. Dopamine was used in dosage of 10 to 30 micrograms/kg per min after the additional administration of a half of the initial dosage of phenoxybenzamine; this was infused by drip always in a dosage of 0.5 to 1.0 mg/kg during the first half of cardiopulmonary bypass. It was possible to come off cardiopulmonary bypass with a stable haemodynamic state (mean arterial pressure more than 60 mmHg and total peripheral vascular resistance less than 2000 bynes s cm-5) and a good urinary output.

  19. Combined use of phenoxybenzamine and dopamine for low cardiac output syndrome in children at withdrawal from cardiopulmonary bypass.

    PubMed Central

    Kawamura, M; Minamikawa, O; Yokochi, H; Maki, S; Yasuda, T; Mizukawa, Y

    1980-01-01

    The combined use of phenoxybenzamine and dopamine was applied in infants and children when it was difficult to come off cardiopulmonary bypass for low cardiac output. The rationale of this method is to prevent the alpha-adrenergic action of dopamine by phenoxybenzamine and to encourage the beta-adrenergic and direct specific action of dopamine. Dopamine was used in dosage of 10 to 30 micrograms/kg per min after the additional administration of a half of the initial dosage of phenoxybenzamine; this was infused by drip always in a dosage of 0.5 to 1.0 mg/kg during the first half of cardiopulmonary bypass. It was possible to come off cardiopulmonary bypass with a stable haemodynamic state (mean arterial pressure more than 60 mmHg and total peripheral vascular resistance less than 2000 bynes s cm-5) and a good urinary output. PMID:7397040

  20. Measured performance parameters of gradiometers with digital output

    SciTech Connect

    Drung, D.; Crocoll, E.; Herwig, R.; Neuhaus, M.; Jutzi, W.

    1989-03-01

    A planar first order gradiometer and a dc SQUID comparator have been integrated on the same 6x6 mm/sup 2/ chip in the Nb-Nb/sub 2/O/sub 5/-PbInAu technology and operated in a flux-locked loop. Owing to the digital gradiometer output, a very low flux noise of 7x10/sup -7/PHI/sub O//..sqrt..Hz, a coupled noise energy of 34 times Planck's constant h and a gradient noise of 3.8 pT/(m..sqrt..Hz) have been achieved in the white noise region above about 60 Hz. In spite of the very low flux noise, a maximum slew rate of 1.5x10/sup 5/ PHI/sub O//s at a signal frequency of 4 kHz has been measured. A simple modulation scheme has been developed to cancel Josephson junction critical current fluctuations yielding 4.5x10/sup -6/ PHI/sub O//..sqrt..Hz at 0.1 Hz.

  1. Nine criteria for a measure of scientific output.

    PubMed

    Kreiman, Gabriel; Maunsell, John H R

    2011-01-01

    Scientific research produces new knowledge, technologies, and clinical treatments that can lead to enormous returns. Often, the path from basic research to new paradigms and direct impact on society takes time. Precise quantification of scientific output in the short-term is not an easy task but is critical for evaluating scientists, laboratories, departments, and institutions. While there have been attempts to quantifying scientific output, we argue that current methods are not ideal and suffer from solvable difficulties. Here we propose criteria that a metric should have to be considered a good index of scientific output. Specifically, we argue that such an index should be quantitative, based on robust data, rapidly updated and retrospective, presented with confidence intervals, normalized by number of contributors, career stage and discipline, impractical to manipulate, and focused on quality over quantity. Such an index should be validated through empirical testing. The purpose of quantitatively evaluating scientific output is not to replace careful, rigorous review by experts but rather to complement those efforts. Because it has the potential to greatly influence the efficiency of scientific research, we have a duty to reflect upon and implement novel and rigorous ways of evaluating scientific output. The criteria proposed here provide initial steps toward the systematic development and validation of a metric to evaluate scientific output.

  2. Nine Criteria for a Measure of Scientific Output

    PubMed Central

    Kreiman, Gabriel; Maunsell, John H. R.

    2011-01-01

    Scientific research produces new knowledge, technologies, and clinical treatments that can lead to enormous returns. Often, the path from basic research to new paradigms and direct impact on society takes time. Precise quantification of scientific output in the short-term is not an easy task but is critical for evaluating scientists, laboratories, departments, and institutions. While there have been attempts to quantifying scientific output, we argue that current methods are not ideal and suffer from solvable difficulties. Here we propose criteria that a metric should have to be considered a good index of scientific output. Specifically, we argue that such an index should be quantitative, based on robust data, rapidly updated and retrospective, presented with confidence intervals, normalized by number of contributors, career stage and discipline, impractical to manipulate, and focused on quality over quantity. Such an index should be validated through empirical testing. The purpose of quantitatively evaluating scientific output is not to replace careful, rigorous review by experts but rather to complement those efforts. Because it has the potential to greatly influence the efficiency of scientific research, we have a duty to reflect upon and implement novel and rigorous ways of evaluating scientific output. The criteria proposed here provide initial steps toward the systematic development and validation of a metric to evaluate scientific output. PMID:22102840

  3. Incidence of arteriovenous fistula closure due to high-output cardiac failure in kidney-transplanted patients.

    PubMed

    Schier, Tabea; Göbel, Georg; Bösmüller, Claudia; Gruber, Ingrid; Tiefenthaler, Martin

    2013-01-01

    Some hemodialysis patients develop arteriovenous (AV) fistulas with high flows. This volume overload can result in high-output cardiac failure. To date, predisposing access flow rates are unknown. A retrospective study of all kidney-transplant recipients at the Medical University of Innsbruck (MUI) from 2005 to 2010 included 797 patients with the following criteria: previous hemodialysis with a native AV fistula or a graft, sufficient function of the kidney transplant up to the time of the data analysis, and follow-up care at the MUI. Twenty-nine of the 113 patients (25.7%) needed an AV fistula closure, mostly because of symptoms of cardiac failure. The mean shunt flow in the intervention group was 2197.2 mL/min, whereas the mean shunt flow in the non-intervention group was only 850.9 mL/min. Shunt closures were most frequently made in patients with upper-arm shunts (41.7%). The necessity of shunt closure is not a rarity. Patients who underwent an AV fistula ligature had high access flows with about 2200 mL/min. As the symptoms of cardiac failure greatly improved after shunt closure, patients with high access flow may benefit from such an intervention. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Distance measurements in cardiac troponin C.

    PubMed

    Wang, C L; Leavis, P C

    1990-01-01

    Intramolecular distance measurements were made in cardiac troponin C (cTnC) by fluorescence energy transfer using Eu3+ or Tb3+ as energy donors and Nd3+ or an organic chromophore as acceptors. The laser-induced luminescence of bound Eu3+ is quenched in Eu1Nd1cTnC with a lifetime of 0.328 ms, compared with 0.43 ms for Eu2cTnC. The enhanced decay corresponds to an energy transfer efficiency of 0.25, or a distance of 1.1 nm between the two high affinity sites. We have also labeled cTnC with 4-dimethylaminophenylazophenyl-4'-maleimide (DAB-Mal) at the two cysteine residues (Cys-35 and Cys-84). Energy transfer measurements were carried out between Tb3+ bound to the high affinity sites and the labels attached to the domain containing the low affinity site. Upon uv irradiation at pH 6.7, Tb1cTnCDAB emits tyrosine-sensitized Tb3+ luminescence that decays bioexponentially with lifetimes of 1.29 and 0.76 ms. The shorter lifetime is ascribed to energy transfer from Tb3+ to the DAB labels, yielding an average distance of 3.4 nm between the donor and the acceptors. At pH 5.0, however, the luminescence decays exclusively with a single lifetime of 1.31 ms, suggesting that under these conditions all Tb3+ ions are more than 5.2 nm away from the label. Thus cTnC, like skeletal TnC, undergoes a pH-dependent conformational transition which converts an elongated structure at lower pH's to a rather compact conformation in a more physiological medium.

  5. Output trends, characteristics, and measurements of three megavoltage radiotherapy linear accelerators.

    PubMed

    Hossain, Murshed

    2014-07-08

    The purpose of this study is to characterize and understand the long-term behavior of the output from megavoltage radiotherapy linear accelerators. Output trends of nine beams from three linear accelerators over a period of more than three years are reported and analyzed. Output, taken during daily warm-up, forms the basis of this study. The output is measured using devices having ion chambers. These are not calibrated by accredited dosimetry laboratory, but are baseline-compared against monthly output which is measured using calibrated ion chambers. We consider the output from the daily check devices as it is, and sometimes normalized it by the actual output measured during the monthly calibration of the linacs. The data show noisy quasi-periodic behavior. The output variation, if normalized by monthly measured "real' output, is bounded between ± 3%. Beams of different energies from the same linac are correlated with a correlation coefficient as high as 0.97, for one particular linac, and as low as 0.44 for another. These maximum and minimum correlations drop to 0.78 and 0.25 when daily output is normalized by the monthly measurements. These results suggest that the origin of these correlations is both the linacs and the daily output check devices. Beams from different linacs, independent of their energies, have lower correlation coefficient, with a maximum of about 0.50 and a minimum of almost zero. The maximum correlation drops to almost zero if the output is normalized by the monthly measured output. Some scatter plots of pairs of beam output from the same linac show band-like structures. These structures are blurred when the output is normalized by the monthly calibrated output. Fourier decomposition of the quasi-periodic output is consistent with a 1/f power law. The output variation appears to come from a distorted normal distribution with a mean of slightly greater than unity. The quasi-periodic behavior is manifested in the seasonally averaged output

  6. Output trends, characteristics, and measurements of three mega-voltage radiotherapy linear accelerators

    PubMed Central

    Hossain, Murshed

    2015-01-01

    The purpose of this study is to characterize and understand the long term behavior of the output from megavoltage radiotherapy linear accelerators. Output trends of nine beams from three linear accelerators over a period of more than three years are reported and analyzed. Output taken during daily warm-up forms the basis of this study. The output is measured using devices having ion-chambers. These are not calibrated by accredited dosimetry laboratory but are baseline compared against monthly output which are measured using calibrated ion-chambers. We consider the output from the daily check devices as it is and sometimes normalized them by the actual output measured during the monthly calibration of the Linacs. The data shows noisy quasi-periodic behavior. The output variation if normalized by monthly measured “real’ output, is bounded between ±3%. Beams of different energies from the same Linac are correlated with a correlation coefficient as high as 0.97 for one particular Linac and as low as 0.44 for another. These maximum and minimum correlations drop to 0.78 and 0.25 when daily output is normalized by the monthly measurements. These results suggest that the origin of these correlations are both the Linacs and the daily output check devices. Beams from different Linacs, independent of their energies, have lower correlation coefficient with a maximum of about 0.50 and a minimum of almost zero. The maximum correlation drops to almost zero if the output is normalized by the monthly measured output. Some scatter plots of pairs of beam-output from the same Linac show band-like structures. These structures are blurred when the output is normalized by the monthly calibrated output. Fourier decomposition of the quasi periodic output is consistent with a 1/f power law. The output variation appears to come from a distorted normal distribution with a mean of slightly greater than unity. The quasi-periodic behavior is manifested in the seasonally averaged output

  7. Reduced heart rate and cardiac output differentially affect angiogenesis, growth, and development in early chicken embryos (Gallus domesticus).

    PubMed

    Branum, Sylvia R; Yamada-Fisher, Miho; Burggren, Warren

    2013-01-01

    An increase in both vascular circumferential tension and shear stress in the developing vasculature of the chicken embryo has been hypothesized to stimulate angiogenesis in the developing peripheral circulation chorioallantoic membrane (CAM). To test this hypothesis, angiogenesis in the CAM, development, and growth were measured in the early chicken embryo, following acute and chronic topical application of the purely bradycardic drug ZD7288. At hour 56, ZD7288 reduced heart rate (f(H)) by ~30% but had no significant effect on stroke volume (~0.19 ± 0.2 μL), collectively resulting in a significant fall in cardiac output (CO) from ~27 ± 3 to 18 ± 2 μL min(-1). Mean f(H) at 72 h of development was similarly significantly lowered by acute ZD7288 treatment (250 μM) to 128 ± 0.3 beats min(-1), compared with 174.5 ± 0.3 and 174.7 ± 0.8 beats min(-1) in control and Pannett-Compton (P-C) saline-treated embryos, respectively. Chronic dosing with ZD7288-and the attendant decreases in f(H) and CO-did not change eye diameter or cervical flexion (key indicators of development rate) at 120 h but significantly reduced overall growth (wet and dry body mass decreased by 20%). CAM vessel density index (reflecting angiogenesis) measured 200-400 μm from the umbilical stalk was not altered, but ZD7288 reduced vessel numbers-and therefore vessel density-by 13%-16% more distally (500-600 μm from umbilical stalk) in the CAM. In the ZD7288-treated embryos, a decrease in vessel length was found within the second branch order (~300-400 μm from the umbilical stock), while a decrease in vessel diameter was found closer to the umbilical stock, beginning in the first branch order (~200-300 μm). Paradoxically, chronic application of P-C saline also reduced peripheral CAM vessel density index at 500 and 600 μm by 13% and 7%, respectively, likely from washout of local angiogenic factors. In summary, decreased f(H) with reduced CO did not slow development rate but reduced embryonic

  8. 47 CFR 2.1046 - Measurements required: RF power output.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Section 2.1046 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1046... frequency load attached to the output terminals when this test is made shall be stated. (b) For...

  9. 47 CFR 2.1046 - Measurements required: RF power output.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Section 2.1046 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1046... frequency load attached to the output terminals when this test is made shall be stated. (b) For...

  10. 47 CFR 2.1046 - Measurements required: RF power output.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Section 2.1046 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1046... frequency load attached to the output terminals when this test is made shall be stated. (b) For...

  11. 47 CFR 2.1046 - Measurements required: RF power output.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Section 2.1046 Telecommunication FEDERAL COMMUNICATIONS COMMISSION GENERAL FREQUENCY ALLOCATIONS AND RADIO TREATY MATTERS; GENERAL RULES AND REGULATIONS Equipment Authorization Procedures Certification § 2.1046... frequency load attached to the output terminals when this test is made shall be stated. (b) For...

  12. Measuring Equity: Creating a New Standard for Inputs and Outputs

    ERIC Educational Resources Information Center

    Knoeppel, Robert C.; Della Sala, Matthew R.

    2013-01-01

    The purpose of this article is to introduce a new statistic to capture the ratio of equitable student outcomes given equitable inputs. Given the fact that finance structures should be aligned to outcome standards according to judicial interpretation, a ratio of outputs to inputs, or "equity ratio," is introduced to discern if conclusions can be…

  13. Measuring Equity: Creating a New Standard for Inputs and Outputs

    ERIC Educational Resources Information Center

    Knoeppel, Robert C.; Della Sala, Matthew R.

    2013-01-01

    The purpose of this article is to introduce a new statistic to capture the ratio of equitable student outcomes given equitable inputs. Given the fact that finance structures should be aligned to outcome standards according to judicial interpretation, a ratio of outputs to inputs, or "equity ratio," is introduced to discern if conclusions can be…

  14. Quality measures for congenital and pediatric cardiac surgery.

    PubMed

    Jacobs, Jeffrey Phillip; Jacobs, Marshall Lewis; Austin, Erle H; Mavroudis, Constantine; Pasquali, Sara K; Lacour-Gayet, Francois G; Tchervenkov, Christo I; Walters, Hal; Bacha, Emile A; Nido, Pedro J Del; Fraser, Charles D; Gaynor, J William; Hirsch, Jennifer C; Morales, David L S; Pourmoghadam, Kamal K; Tweddell, James S; Prager, Richard L; Mayer, John E

    2012-01-01

    This article presents 21 "Quality Measures for Congenital and Pediatric Cardiac Surgery" that were developed and approved by the Society of Thoracic Surgeons (STS) and endorsed by the Congenital Heart Surgeons' Society (CHSS). These Quality Measures are organized according to Donabedian's Triad of Structure, Process, and Outcome. It is hoped that these quality measures can aid in congenital and pediatric cardiac surgical quality assessment and quality improvement initiatives.

  15. Evaluating cardiac physiology through echocardiography in bottlenose dolphins: using stroke volume and cardiac output to estimate systolic left ventricular function during rest and following exercise.

    PubMed

    Miedler, Stefan; Fahlman, Andreas; Valls Torres, Mónica; Álvaro Álvarez, Teresa; Garcia-Parraga, Daniel

    2015-11-01

    Heart-rate (fH) changes during diving and exercise are well documented for marine mammals, but changes in stroke volume (SV) and cardiac output (CO) are much less known. We hypothesized that both SV and CO are also modified following intense exercise. Using transthoracic ultrasound Doppler at the level of the aortic valve, we compared blood flow velocities in the left ventricle and cardiac frequencies during rest and at 1, 3 and 4 min after a bout of exercise in 13 adult bottlenose dolphins (Tursiops truncatus, six male and seven female, body mass range 143-212 kg). Aortic cross-sectional area and ventricle blood velocity at the aortic valve were used to calculate SV, which together with fH provided estimates of left CO at rest and following exercise. fH and SV stabilized approximately 4-7 s following the post-respiratory tachycardia, so only data after the fH had stabilized were used for analysis and comparison. There were significant increases in fH, SV and CO associated with each breath. At rest, fH, SV and CO were uncorrelated with body mass, and averaged 41±9 beats min(-1), 136±19 ml and 5514±1182 l min(-1), respectively. One minute following high intensity exercise, the cardiac variables had increased by 104±43%, 63±11% and 234±84%, respectively. All variables remained significantly elevated in all animals for at least 4 min after the exercise. These baseline values provide the first data on SV and CO in awake and unrestrained cetaceans in water.

  16. Cardiac output, pulmonary artery pressure, and patent ductus arteriosus during therapeutic cooling after global hypoxia-ischaemia.

    PubMed

    Fugelseth, D; Satas, S; Steen, P A; Thoresen, M

    2003-05-01

    To assess by Doppler echocardiography the effects of 24 hours of whole body mild hypothermia compared with normothermia on cardiac output (CO), pulmonary artery pressure (PAP), and the presence of a persistent ductus arteriosus (PDA) after a global hypoxic-ischaemic insult in unsedated newborn animals. Thirty five pigs (mean (SD) age 26.6 (12.1) hours and weight 1.6 (0.3) kg) were anaesthetised with halothane, mechanically ventilated, and subjected to a 45 minute global hypoxic-ischaemic insult. At the end of hypoxia, halothane was stopped; the pigs were randomised to either normathermia (39 degrees C) or hypothermia (35 degrees C) for 24 hours. Rewarming was carried out for 24-30 hours followed by 42 hours of normothermia. Unanaesthetised pigs were examined with a VingMed CFM 750 ultrasound scanner before and 3, 24, 30, and 48 hours after the hypoxic-ischaemic insult. Aortic valve diameter, forward peak flow velocities across the four valves, and the occurrence of a PDA were measured. Tricuspid regurgitation (TR) velocity was used to estimate the PAP. Stroke volume was calculated from the aortic flow. Twelve animals (seven normothermic, five hypothermic) had a PDA on one or more examinations, which showed no association with cooling or severity of insult. There were no differences in stroke volume or TR velocity between the hypothermic and normothermic animals at any time point after the insult. CO was, however, 45% lower at the end of cooling in the subgroup of hypothermic pigs that had received a severe insult compared with the pigs with mild and moderate insults. CO and TR velocity were transiently increased three hours after the insult: 0.38 (0.08) v 0.42 (0.08) litres/min/kg (p = 0.007) for CO; 3.0 (0.42) v 3.4 (0.43) m/s (p < 0.0001) for TR velocity (values are mean (SD)). The introduction of mild hypothermia while the pigs were unsedated did not affect the incidence of PDA nor did it lead to any changes in MABP or PAP. Stroke volume was also unaffected by

  17. Oesophageal Doppler guided optimization of cardiac output does not increase visceral microvascular blood flow in healthy volunteers.

    PubMed

    Heinink, Thomas P; Read, David J; Mitchell, William K; Bhalla, Ashish; Lund, Jonathan N; Phillips, Bethan E; Williams, John P

    2017-02-06

    Oesophageal Doppler monitoring (ODM) is used clinically to optimize cardiac output (CO) and guide fluid therapy. Despite limited experimental evidence, it is assumed that increasing CO increases visceral microvascular blood flow (MBF). We used contrast-enhanced ultrasound (CEUS) to assess whether ODM-guided optimization of CO altered MBF. Sixteen healthy male volunteers (62 ± 3·4 years) were studied. Baseline measurements of CO were recorded via ODM. Hepatic and renal MBF was assessed via CEUS. Saline 0·9% was administered to optimize CO according to a standard protocol and repeat CEUS performed. Time-intensity curves were constructed, allowing organ perfusion calculation via time to 5% perfusion (TT5). MBF was assessed via organ perfusion rise time (RT) (5-95%). CO increased (4535 ± 241 ml/min versus 5442 ± 329 ml/min, P<0·0001) following fluid administration, whilst time to renal (22·48 ± 1·19 s versus 20·79 ± 1·31 s; P = 0·03), but not hepatic (28·13 ± 4·48 s versus 26·83 ± 1·53 s; P = 0·15) perfusion decreased. Time to renal perfusion was related to CO (renal: r = -0·43, P = 0·01). Hepatic nor renal RT altered following fluid administration (renal: 9·03 ± 0·86 versus 8·93 ± 0·85 s P = 0·86; hepatic: 27·86 ± 1·60 s versus 30·71 ± 2·19 s, P = 0·13). No relationship was observed between changes in CO and MBF in either organ (renal: r = -0·17, P = 0·54; hepatic: r = -0·07, P = 0·80). ODM-optimized CO reduces time to renal perfusion but does not alter renal or hepatic MBF. A lack of relationship between microvascular visceral perfusion and CO following ODM-guided optimization may explain the absence of improved clinical outcome with ODM monitoring. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  18. Effects of cardiac phase on diameter measurements from coronary cineangiograms

    NASA Technical Reports Server (NTRS)

    Selzer, Robert H.; Siebes, Maria; Lee, Paul L.; Hagerty, Cheryl; Azen, P.

    1989-01-01

    The measurement variability of end-diastolic frames is compared with frames taken from the other portions of the cardiac cycle. Two computer measurements, average diameter and minimum, are obtained for every frame of two complete cardiac cycles in angiograms of 20 subjects. Six schemes for sampling frames in various portions of the cardiac cycle are defined and the standard deviation is calculated for pairs of measurements from each scheme. The results suggest that the best strategy for frame selection is to use sequential frames in end-diastole. However, it is noted that if random samples are taken anywhere in the cardiac cycle instead of sequentially in end-diastole, the variability of two vessel edge measures changes from 4.9 percent to 6.3 percent, which is considered to be a small penalty.

  19. Comparison of cardiac power output and exercise performance in patients with left ventricular assist devices, explanted (recovered) patients, and those with moderate to severe heart failure.

    PubMed

    Jakovljevic, Djordje G; George, Robert S; Donovan, Gay; Nunan, David; Henderson, Keiran; Bougard, Robert S; Yacoub, Magdi H; Birks, Emma J; Brodie, David A

    2010-06-15

    Peak cardiac power output (CPO), as a direct measurement of overall cardiac function, has been shown to be a most powerful predictor of prognosis for patients with chronic heart failure. The present study assessed CPO and exercise performance in patients implanted with a left ventricular assist device (LVAD), those explanted due to myocardial recovery, and those with moderate to severe heart failure. Hemodynamic and respiratory gas exchange measurements were undertaken at rest and at peak graded exercise. These were performed in 54 patients-20 with moderate to severe heart failure, 18 with implanted LVADs, and 16 with explanted LVADs. At rest there was a nonsignificant difference in CPO among groups (p >0.05). Peak CPO was significantly higher in the explanted LVAD than in the heart failure and implanted LVAD groups (heart failure 1.90 +/- 0.45 W, implanted LVAD 2.37 +/- 0.55 W, explanted LVAD 3.39 +/- 0.61 W, p <0.01) as was peak cardiac output (heart failure 9.1 +/- 2.1 L/min, implanted LVAD 12.4 +/- 2.2 L/min, explanted LVD 14.6 +/- 2.9 L/min, p <0.01). Peak oxygen consumption was higher in the explanted LVAD than in the heart failure and implanted LVAD groups (heart failure 15.8 +/- 4.1 ml/kg/min, implanted LVAD 19.8 +/- 5.8 ml/kg/min, explanted LVAD 28.2 +/- 5.0 ml/kg/min, p <0.05) as was anaerobic threshold (heart failure 11.2 +/- 1.9 ml/kg/min, implanted LVAD 14.7 +/- 4.9 ml/kg/min, explanted LVAD 21.4 +/- 5.0 ml/kg/min, p <0.05). In conclusion, peak CPO differentiates well during cardiac restoration using LVADs and emphasizes the benefits of this therapy. CPO has the potential to be a key physiologic marker of heart failure severity and can guide management of patients with LVAD.

  20. The use of a cardiac output monitor to guide the initial fluid resuscitation in a patient with burns

    PubMed Central

    Reid, Robert Darren; Jayamaha, John

    2007-01-01

    A case of initial resuscitation of a patient with severe burns is described. Such patients can have hypotension and reduced organ perfusion for a number of reasons, and can remain in the emergency department for many hours while awaiting transfer to specialist centres. The case provides a comparison between resuscitation using traditional burns formulae and a relatively new and simple‐to‐use cardiac output (CO) monitor—the Vigileo monitor (Edwards Lifesciences, Irvine, California, USA). The case demonstrates that relying on fluid regimes alone can lead to insufficient resuscitation. We suggest that using technologies such as those mentioned in this article, which have the potential to be used in the emergency department, could improve the initial resuscitation of patients with burns. PMID:17452692

  1. A review of intraoperative goal-directed therapy using arterial waveform analysis for assessment of cardiac output.

    PubMed

    Mehta, Neil; Fernandez-Bustamante, Ana; Seres, Tamas

    2014-01-01

    Increasing evidence shows that goal-directed hemodynamic management can improve outcomes in surgical and intensive care settings. Arterial waveform analysis is one of the different techniques used for guiding goal-directed therapy. Multiple proprietary systems have developed algorithms for obtaining cardiac output from an arterial waveform, including the FloTrac, LiDCO, and PiCCO systems. These systems vary in terms of how they analyze the arterial pressure waveform as well as their requirements for invasive line placement and calibration. Although small-scale clinical trials using these monitors show promising data, large-scale multicenter trials are still needed to better determine how intraoperative goal-directed therapy with arterial waveform analysis can improve patient outcomes. This review provides a comparative analysis of the different arterial waveform monitors for intraoperative goal-directed therapy.

  2. Construct, concurrent and discriminant validity of Type D personality in the general population: associations with anxiety, depression, stress and cardiac output.

    PubMed

    Howard, Siobhán; Hughes, Brian M

    2012-01-01

    The Type D personality, identified by high negative affectivity paired with high social inhibition, has been associated with a number of health-related outcomes in (mainly) cardiac populations. However, despite its prevalence in the health-related literature, how this personality construct fits within existing personality theory has not been directly tested. Using a sample of 134 healthy university students, this study examined the Type D personality in terms of two well-established personality traits; introversion and neuroticism. Construct, concurrent and discriminant validity of this personality type was established through examination of the associations between the Type D personality and psychometrically assessed anxiety, depression and stress, as well as measurement of resting cardiovascular function. Results showed that while the Type D personality was easily represented using alternative measures of both introversion and neuroticism, associations with anxiety, depression and stress were mainly accounted for by neuroticism. Conversely, however, associations with resting cardiac output were attributable to the negative affectivity-social inhibition synergy, explicit within the Type D construct. Consequently, both the construct and concurrent validity of this personality type were confirmed, with discriminant validity evident on examination of physiological indices of well-being.

  3. Comparison of Levosimendan, Milrinone and Dobutamine in treating Low Cardiac Output Syndrome Following Valve Replacement Surgeries with Cardiopulmonary Bypass

    PubMed Central

    Sunny; Karim, Habib Md Reazaul; Saikia, Manuj Kumar; Bhattacharyya, Prithwis; Dey, Samarjit

    2016-01-01

    Introduction Low Cardiac Output Syndrome (LCOS) following Cardiopulmonary Bypass (CPB) is common and associated with increased mortality. Maintenance of adequate cardiac output is one of the primary objectives in management of such patients. Aim To compare Levosimendan, Milrinone and Dobutamine for the treatment of LCOS after CPB in patients who underwent valve replacement surgeries. Materials and Methods Sixty eligible patients meeting LCOS were allocated into three treatment groups: Group A-Levosimendan (loading dose 10μg/kg over 10 minutes, followed by 0.1μg/kg/min); Group B-Milrinone (loading dose 50 mcg/kg over 10 minutes followed by 0.5mcg/kg/min) and Group C-Dobutamine @ 5μg/kg/min to achieve target cardiac index (CI) of > 2.5 L/min/m2. In case of failure, other drugs were added as required. Hemodynamic parameters were monitored using EV1000TM clinical platform till 30 minutes post CPB. INSTAT software was used for statistics and p<0.05 was considered significant. Results The mean±standard deviation of time taken by Dobutamine, Levosimendan and Milrinone to bring the CI to target were 11.1±8.79, 11.3±6.34 and 16.62±9.33 minutes respectively (p=0.064). Levosimendan was equally effective in increasing and maintaining adequate CI as compared to Dobutamine (p>0.05). Levosimendan and Milrinone increased MAP (Mean Arterial Pressure) equally while Dobutamine was more effective as compared to both Levosimendan and Milrinone 20th minute onwards (p<0.01). Milrinone was less effective in increasing the stroke volume as compared to Dobutamine and Levosimendan while Dobutamine and Levosimendan were equally effective. There was no difference in the HR (Heart Rate) achieved with all these three drugs. Conclusion Levosimendan is equally effective to Dobutamine and better than Milrinone for the treatment of LCOS following CPB in patients undergoing valve replacement surgeries. PMID:28208977

  4. Continuous cardiac output and left atrial pressure monitoring by long time interval analysis of the pulmonary artery pressure waveform: proof of concept in dogs.

    PubMed

    Xu, Da; Olivier, N Bari; Mukkamala, Ramakrishna

    2009-02-01

    We developed a technique to continuously (i.e., automatically) monitor cardiac output (CO) and left atrial pressure (LAP) by mathematical analysis of the pulmonary artery pressure (PAP) waveform. The technique is unique to the few previous related techniques in that it jointly estimates the two hemodynamic variables and analyzes the PAP waveform over time scales greater than a cardiac cycle wherein wave reflections and inertial effects cease to be major factors. First, a 6-min PAP waveform segment is analyzed so as to determine the pure exponential decay and equilibrium pressure that would eventually result if cardiac activity suddenly ceased (i.e., after the confounding wave reflections and inertial effects vanish). Then, the time constant of this exponential decay is computed and assumed to be proportional to the average pulmonary arterial resistance according to a Windkessel model, while the equilibrium pressure is regarded as average LAP. Finally, average proportional CO is determined similar to invoking Ohm's law and readily calibrated with one thermodilution measurement. To evaluate the technique, we performed experiments in five dogs in which the PAP waveform and accurate, but highly invasive, aortic flow probe CO and LAP catheter measurements were simultaneously recorded during common hemodynamic interventions. Our results showed overall calibrated CO and absolute LAP root-mean-squared errors of 15.2% and 1.7 mmHg, respectively. For comparison, the root-mean-squared error of classic end-diastolic PAP estimates of LAP was 4.7 mmHg. On future successful human testing, the technique may potentially be employed for continuous hemodynamic monitoring in critically ill patients with pulmonary artery catheters.

  5. Effect of cardiac output on gas exchange in one-lung atelectasis.

    PubMed

    Mathru, M; Dries, D J; Kanuri, D; Blakeman, B; Rao, T

    1990-05-01

    To evaluate the effect of administration of dobutamine on gas exchange in patients with one-lung atelectasis during pneumonectomy, ten patients with normal pulmonary function and localized carcinoma of the lung were studied during pulmonary resection. With each patient in the lateral decubitus position, hemodynamic profiles and oxygen transport data were recorded before and after administration of dobutamine at 5 micrograms/kg/min. Patients were ventilated with one-lung anesthesia and administration of 100 percent oxygen. With infusion of dobutamine, the heart rate, cardiac index, and LVSWI significantly increased. Mean arterial pressure increased while PAP fell. Systemic and pulmonary vascular resistance also declined. Arterial oxygenization and delivery improved, while oxygen uptake was unchanged. Pulmonary shunt fraction was significantly reduced. While the mechanism for shunt reduction in our patients is unclear, operative factors may include pulmonary vasodilation with dobutamine inhibition of HPV. The negative impact of reduced HPV may have been lessened by gravitational distribution of blood flow and dobutamine-mediated reduction in PAP in our patients.

  6. A critique of impedance measurements in cardiac tissue.

    PubMed

    Plonsey, R; Barr, R C

    1986-01-01

    The specific impedance of cardiac tissue cannot be measured directly. Instead, the investigator obtains voltage and current measurements and places them into a model of the tissue's structure to infer the impedances of elements of the model. If the model fails to describe major aspects of the real tissue, the results may be worthless, although possibly self-consistent. In the literature of impedance measurement in cardiac tissue, only rarely is the model explicitly described; more commonly, the tissue model is adopted implicitly when equations giving the impedance in terms of voltage and current measurements are adopted. This paper examines the series of models that have been used in specific impedance measurements of cardiac tissue and shows how the same or similar measurements can accurately describe tissue impedivity or can lead to significant errors when inadequate models such as isotropic and anisotropic monodomains (although a part of work of historical merit) are used.

  7. Effect of increased cardiac output on liver blood flow, oxygen exchange and metabolic rate during longterm endotoxin-induced shock in pigs

    PubMed Central

    Šantak, Borislav; Radermacher, Peter; Adler, Jens; Iber, Thomas; Rieger, Karen M; Wachter, Ulrich; Vogt, Josef; Georgieff, Michael; Träger, Karl

    1998-01-01

    We investigated hepatic blood flow, O2 exchange and metabolism in porcine endotoxic shock (Control, n=8; Endotoxin, n=10) with administration of hydroxyethylstarch to maintain arterial pressure (MAP)>60 mmHg. Before and 12, 18 and 24 h after starting continuous i.v. endotoxin we measured portal venous and hepatic arterial blood flow, intracapillary haemoglobin O2 saturation (Hb-O2%) of the liver surface and arterial, portal and hepatic venous lactate, pyruvate, glyercol and alanine concentrations. Glucose production rate was derived from the plasma isotope enrichment during infusion of [6,6-2H2]-glucose. Despite a sustained 50% increase in cardiac output endotoxin caused a progressive, significant fall in MAP. Liver blood flow significantly increased, but endotoxin affected neither hepatic O2 delivery and uptake nor mean intracapillary Hb-O2% and Hb-O2% frequency distributions. Endotoxin nearly doubled endogenous glucose production rate while hepatic lactate, alanine and glycerol uptake rates progressively decreased significantly. The lactate uptake rate even became negative (P<0.05 vs Control). Endotoxin caused portal and hepatic venous pH to fall significantly concomitant with significantly increased arterial, portal and hepatic venous lactate/pyruvate ratios. During endotoxic shock increased cardiac output achieved by colloid infusion maintained elevated liver blood flow and thereby macro- and microcirculatory O2 supply. Glucose production rate nearly doubled with complete dissociation of hepatic uptake of glucogenic precursors and glucose release. Despite well-preserved capillary oxygenation increased lactate/pyruvate ratios reflecting impaired cytosolic redox state suggested deranged liver energy balance, possibly due to the O2 requirements of gluconeogenesis. PMID:9756385

  8. The effect of lidocaine on regional blood flows and cardiac output in the non-stressed and the stressed foetal lamb.

    PubMed

    Friesen, C; Yarnell, R; Bachman, C; Meatheral, R; Biehl, D

    1986-03-01

    Lidocaine has been used in obstetrical anaesthesia for many years but there are still concerns about possible adverse affects of this drug on the foetus in utero. To examine in greater detail the effects of lidocaine in the foetus, the following two-part study was done. In Part A, seven pregnant ewes were surgically prepared with maternal and foetal arterial and venous catheters. After recovery from surgery lidocaine was infused intravenously, initially into the ewe and then into both ewe and foetus. Blood lidocaine concentrations were monitored and foetal regional blood flows were determined by the radioactive microsphere method. In Part B, 14 ewes were prepared as in Part A with the addition of an inflatable loop around the umbilical cord. During each study the loop was inflated to partially compress the cord and produce foetal acidosis. In all animals this cord compression was maintained for 30 minutes. In seven animals a lidocaine infusion was given, to examine the effect of lidocaine in the acidotic foetus. Organ blood flows were measured and cardiac outputs calculated. The normal foetuses in Part A showed no change in organ blood flow or cardiac output with arterial lidocaine concentrations of 1.5-3.4 mg X ml-1. In the acidotic foetuses, lidocaine concentrations of 1.4-1.5 mg X ml-1 produced a tachycardia and an increase in cerebral blood flow compared to the control acidotic foetuses. There were no other significant changes. We conclude that arterial lidocaine concentrations of less than 3.5 mg X ml-1 do not produce significant alterations in organ blood flow in normal foetal lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

  9. Role of cardiac output and the autonomic nervous system in the antinatriuretic response to acute constriction of the thoracic superior vena cava.

    NASA Technical Reports Server (NTRS)

    Schrier, R. W.; Humphreys, M. H.; Ufferman, R. C.

    1971-01-01

    Study of the differential characteristics of hepatic congestion and decreased cardiac output in terms of potential afferent stimuli in the antinatriuretic effect of acute thoracic inferior vena cava (TIVC) constriction. An attempt is made to see if the autonomic nervous system is involved in the antinatriuretic effect of acute TIVC or thoracic superior vena cava constriction.

  10. Role of cardiac output and the autonomic nervous system in the antinatriuretic response to acute constriction of the thoracic superior vena cava.

    NASA Technical Reports Server (NTRS)

    Schrier, R. W.; Humphreys, M. H.; Ufferman, R. C.

    1971-01-01

    Study of the differential characteristics of hepatic congestion and decreased cardiac output in terms of potential afferent stimuli in the antinatriuretic effect of acute thoracic inferior vena cava (TIVC) constriction. An attempt is made to see if the autonomic nervous system is involved in the antinatriuretic effect of acute TIVC or thoracic superior vena cava constriction.

  11. Poor accuracy of noninvasive cardiac output monitoring using bioimpedance cardiography [PhysioFlow(R)] compared to magnetic resonance imaging in pediatric patients.

    PubMed

    Taylor, Katherine; Manlhiot, Cedric; McCrindle, Brian; Grosse-Wortmann, Lars; Holtby, Helen

    2012-04-01

    Identification of low cardiac output (CO) states in anesthesia is important because preoperative hemodynamic optimization may improve outcome in surgery. Accurate real-time CO measurement would be useful in optimizing "goal-directed" therapy. We sought to evaluate the reliability and accuracy of CO measurement using bioimpedance cardiography (PhysioFlow®, NeuMeDx, Bristol, PA) in pediatric patients with and without cardiac disease undergoing anesthesia for magnetic resonance imaging (MRI). All consenting patients undergoing anesthesia for cardiac MRI were enrolled. After equilibration of anesthesia for ≥10 minutes, 6 PhysioFlow electrodes were applied to the patient's chest for continuous real-time monitoring for 10 minutes. Data were stored in 15-second epochs and later averaged offline to obtain CO. Phase contrast MRI measurements of flow volumes in the superior vena cava and ascending and descending aorta were made from a single imaging plane through all 3 vessels at the level of the right pulmonary artery. Both CO measurements were indexed to body surface area. The anesthetic technique was the same for both measurements. Agreement was assessed using Bland-Altman analysis. Thirty-one patients were enrolled and 23 were analyzed. The median age at study was 2.8 years (range, 0.02-8.02 years) and median body surface area was 0.54 m(2) (range, 0.21-1.00 m(2)). Eleven of the 23 patients (48%) were males. Patients were grouped into those with univentricular physiology, 6 of 23 (26%); biventricular physiology with shunt, 3 of 23 (13%); biventricular without shunt, 10 of 23 (43%); and no structural heart disease, 4 of 23 (17%). The mean bias was -0.34 ± 1.50 L/min/m(2) (P = 0.29). The 95% limits of agreement were -3.21 to +2.69 L/min/m(2). Only 8 of 23 measurements (35%) were within 20% and 14 of 23 measurements (61%) were within 30% of each other. PhysioFlow performance was not sufficiently accurate in this population. Modifications of the algorithm and further

  12. Optimizing Cardiac Out-Put to Increase Cerebral Penumbral Perfusion in Large Middle Cerebral Artery Ischemic Lesion-OPTIMAL Study.

    PubMed

    Fuhrer, Hannah; Günther, Albrecht; Zinke, Jan; Niesen, Wolf-Dirk

    2017-01-01

    In unsuccessful vessel recanalization, clinical outcome of acute stroke patients depends on early improvement of penumbral perfusion. So far, mean arterial blood pressure (MAP) is the target hemodynamic parameter. However, the correlations of MAP to cardiac output (CO) and cerebral perfusion are volume state dependent. In severe subarachnoid hemorrhage, optimizing CO leads to a reduction of delayed ischemic neurological deficits and improvement of clinical outcome. This study aims to investigate the effect of standard versus advanced cardiac monitoring with optimization of CO on the clinical outcome in patients with large ischemic stroke. The OPTIMAL study is a prospective, multicenter, open, into two arms (1:1) randomized, controlled trial. Sample size estimate: sample sizes of 150 for each treatment group (300 in total) ensure an 80% power to detect a difference of 16% of a dichotomized level of functional clinical outcome at 3 months at a significance level of 0.05. Study outcomes: the primary endpoint is the functional outcome at 3 months. The secondary endpoints include functional outcome at 6 months follow-up, and complications related to hemodynamic monitoring and therapies. The results of this trial will provide data on the safety and efficacy of advanced hemodynamic monitoring on clinical outcome. The trial was approved by the leading ethics committee of Freiburg University, Germany (438/14, 2015) and the local ethics committees of the participating centers. The study is performed in accordance with the Declaration of Helsinki and the guidelines of Good Clinical Practice. It is registered in the German Clinical Trial register (DRKS; DRKS00007805). Dissemination will include submission to peer-reviewed professional journals and presentation at congresses. Hemodynamic monitoring may be altered in a specific stroke patient cohort if the study shows that advanced monitoring is safe and improves the functional outcome.

  13. Effects of gradual volume loading on left ventricular diastolic function in dogs: implications for the optimisation of cardiac output.

    PubMed Central

    Fragata, J.; Areias, J. C.

    1996-01-01

    BACKGROUND: Volume loading is commonly used to adjust preload and optimise cardiac output. It is difficult to monitor preload at the bedside because filling affects ventricular diastolic function and consequently end diastolic pressure, which is the variable used to monitor preload. OBJECTIVE: To assess the effects of gradual volume loading on the different components of left ventricular diastolic function---filling velocities, relaxation, and chamber compliance---to identify how excessive loading produces diastolic dysfunction. METHODS AND RESULTS: Eight mongrel dogs, anaesthetised and mechanically ventilated with both the chest and the pericardium closed, were studied during basal conditions (B), during gradual volume loading with physiological saline---5 ml/kg (VL5), 10 ml/kg (VL10), and 15 ml/kg (VL15)---and during infusion of isosorbide dinitrate (10 g/kg/min) started after the VL15 load was achieved. Dogs were monitored haemodynamically and by transthoracic Doppler echocardiography to assess peak modal velocities of the E and A waves, E/A ratios, and the deceleration time of the E wave. M mode recordings of aligned mitral and aortic valve motion were also obtained to calculate the isovolumic relaxation time. Effects of volume loading on ventricular diastolic function seemed to occur in two phases. Small and moderate volume loads (VL5 and VL10) promoted early ventricular filling, increasing E wave velocities, improving the mean (SD) E/A ratio from 1.95 (0.3) (B) to 2.0 (0.27) (VL5) and 2.6 (0.3) (VL10) (P < 0.00005), prolonging the E wave deceleration time, and only slightly increasing ventricular diastolic pressures. These changes suggest an improvement in ventricular compliance. Extreme volume loads (VL15) produced an abrupt reduction in early ventricular filling, which was transfered to late in diastole, by decreasing E wave velocity, by increasing A wave velocity, and by decreasing E/A ratio from 2.6 (0.3) (VL10) to 0.8 (0.05) (VL15) (P < 0.00005). The E

  14. 40 CFR 92.116 - Engine output measurement system calibrations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... gravitational constant at the test site may be accounted for if desired. (B) Lever arm. A lever arm with a... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device...

  15. 40 CFR 92.116 - Engine output measurement system calibrations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... gravitational constant at the test site may be accounted for if desired. (B) Lever arm. A lever arm with a... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device...

  16. 40 CFR 92.116 - Engine output measurement system calibrations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... gravitational constant at the test site may be accounted for if desired. (B) Lever arm. A lever arm with a... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device...

  17. 40 CFR 92.116 - Engine output measurement system calibrations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... gravitational constant at the test site may be accounted for if desired. (B) Lever arm. A lever arm with a... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device...

  18. 40 CFR 92.116 - Engine output measurement system calibrations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... gravitational constant at the test site may be accounted for if desired. (B) Lever arm. A lever arm with a... performed with the dynamometer operating at a constant speed. The flywheel torque measurement device...

  19. The "systolic volume balance" method for the noninvasive estimation of cardiac output based on pressure wave analysis.

    PubMed

    Papaioannou, Theodore G; Vardoulis, Orestis; Stergiopulos, Nikos

    2012-05-15

    Cardiac output (CO) monitoring is essential for the optimal management of critically ill patients. Several mathematical methods have been proposed for CO estimation based on pressure waveform analysis. Most of them depend on invasive recording of blood pressure and require repeated calibrations, and they suffer from decreased accuracy under specific conditions. A new systolic volume balance (SVB) method, including a simpler empirical form (eSVB), was derived from basic physical principles that govern blood flow and, in particular, a volume balance approach for the conservation of mass ejected into and flowed out of the arterial system during systole. The formulas were validated by a one-dimensional model of the systemic arterial tree. Comparisons of CO estimates between the proposed and previous methods were performed in terms of agreement and accuracy using "real" CO values of the model as a reference. Five hundred and seven different hemodynamic cases were simulated by altering cardiac period, arterial compliance, and resistance. CO could be accurately estimated by the SVB method as follows: CO = C × PP(ao)/(T - P(sm) × T(s)/P(m)) and by the eSVB method as follows: CO = k × C × PP(ao)/T, where C is arterial compliance, PP(ao) is aortic pulse pressure, T is cardiac period, P(sm) is mean systolic pressure, T(s) is systolic duration, P(m) is mean pressure, and k is an empirical coefficient. SVB applied on aortic pressure waves did not require calibration or empirical correction for CO estimation. An empirical coefficient was necessary for brachial pressure wave analysis. The difference of SVB-derived CO from model CO (for brachial waves) was 0.042 ± 0.341 l/min, and the limits of agreement were -0.7 to 0.6 l/min, indicating high accuracy. The intraclass correlation coefficient and root mean square error between estimated and "real" CO were 0.861 and 0.041 l/min, respectively, indicating very good accuracy. eSVB also provided accurate estimation of CO. An in

  20. Output power distributions of mobile radio base stations based on network measurements

    NASA Astrophysics Data System (ADS)

    Colombi, D.; Thors, B.; Persson, T.; Wirén, N.; Larsson, L.-E.; Törnevik, C.

    2013-04-01

    In this work output power distributions of mobile radio base stations have been analyzed for 2G and 3G telecommunication systems. The approach is based on measurements in selected networks using performance surveillance tools part of the network Operational Support System (OSS). For the 3G network considered, direct measurements of output power levels were possible, while for the 2G networks, output power levels were estimated from measurements of traffic volumes. Both voice and data services were included in the investigation. Measurements were conducted for large geographical areas, to ensure good overall statistics, as well as for smaller areas to investigate the impact of different environments. For high traffic hours, the 90th percentile of the averaged output power was found to be below 65% and 45% of the available output power for the 2G and 3G systems, respectively.

  1. Pulmonary tissue volume, cardiac output, and diffusing capacity in sustained microgravity

    NASA Technical Reports Server (NTRS)

    Verbanck, S.; Larsson, H.; Linnarsson, D.; Prisk, G. K.; West, J. B.; Paiva, M.

    1997-01-01

    In microgravity (microG) humans have marked changes in body fluids, with a combination of an overall fluid loss and a redistribution of fluids in the cranial direction. We investigated whether interstitial pulmonary edema develops as a result of a headward fluid shift or whether pulmonary tissue fluid volume is reduced as a result of the overall loss of body fluid. We measured pulmonary tissue volume (Vti), capillary blood flow, and diffusing capacity in four subjects before, during, and after 10 days of exposure to microG during spaceflight. Measurements were made by rebreathing a gas mixture containing small amounts of acetylene, carbon monoxide, and argon. Measurements made early in flight in two subjects showed no change in Vti despite large increases in stroke volume (40%) and diffusing capacity (13%) consistent with increased pulmonary capillary blood volume. Late in-flight measurements in four subjects showed a 25% reduction in Vti compared with preflight controls (P < 0.001). There was a concomittant reduction in stroke volume, to the extent that it was no longer significantly different from preflight control. Diffusing capacity remained elevated (11%; P < 0.05) late in flight. These findings suggest that, despite increased pulmonary perfusion and pulmonary capillary blood volume, interstitial pulmonary edema does not result from exposure to microG.

  2. Pulmonary tissue volume, cardiac output, and diffusing capacity in sustained microgravity

    NASA Technical Reports Server (NTRS)

    Verbanck, S.; Larsson, H.; Linnarsson, D.; Prisk, G. K.; West, J. B.; Paiva, M.

    1997-01-01

    In microgravity (microG) humans have marked changes in body fluids, with a combination of an overall fluid loss and a redistribution of fluids in the cranial direction. We investigated whether interstitial pulmonary edema develops as a result of a headward fluid shift or whether pulmonary tissue fluid volume is reduced as a result of the overall loss of body fluid. We measured pulmonary tissue volume (Vti), capillary blood flow, and diffusing capacity in four subjects before, during, and after 10 days of exposure to microG during spaceflight. Measurements were made by rebreathing a gas mixture containing small amounts of acetylene, carbon monoxide, and argon. Measurements made early in flight in two subjects showed no change in Vti despite large increases in stroke volume (40%) and diffusing capacity (13%) consistent with increased pulmonary capillary blood volume. Late in-flight measurements in four subjects showed a 25% reduction in Vti compared with preflight controls (P < 0.001). There was a concomittant reduction in stroke volume, to the extent that it was no longer significantly different from preflight control. Diffusing capacity remained elevated (11%; P < 0.05) late in flight. These findings suggest that, despite increased pulmonary perfusion and pulmonary capillary blood volume, interstitial pulmonary edema does not result from exposure to microG.

  3. An efficient method of measuring the 4 mm helmet output factor for the Gamma Knife

    NASA Astrophysics Data System (ADS)

    Ma, Lijun; Li, X. Allen; Yu, Cedric X.

    2000-03-01

    It is essential to have accurate measurements of the 4 mm helmet output factor in the treatment of trigeminal neuralgia patients using the Gamma Knife. Because of the small collimator size and the sharp dose gradient at the beam focus, this measurement is generally tedious and difficult. We have developed an efficient method of measuring the 4 mm helmet output factor using regular radiographic films. The helmet output factor was measured by exposing a single Kodak XV film in the standard Leksell spherical phantom using the 18 mm helmet with 30-40 of its plug collimators replaced by the 4 mm plug collimators. The 4 mm helmet output factor was measured to be 0.876 ± 0.009. This is in excellent agreement with our EGS4 Monte Carlo simulated value of 0.876 ± 0.005. This helmet output factor value also agrees with more tedious TLD, diode and radiochromic film measurements that were each obtained using two separate measurements with the 18 mm helmet and the 4 mm helmet respectively. The 4 mm helmet output factor measured by the diode was 0.884 ± 0.016, and the TLD measurement was 0.890 ± 0.020. The radiochromic film measured value was 0.870 ± 0.018. Because a single-exposure measurement was performed instead of a double-exposure measurement, most of the systematic errors that appeared in the double-exposure measurements due to experimental setup variations were cancelled out. Consequently, the 4 mm helmet output factor is more precisely determined by the single-exposure approach. Therefore, routine measurement and quality assurance of the 4 mm helmet output factor of the Gamma Knife could be efficiently carried out using the proposed single-exposure technique.

  4. Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil.

    PubMed

    Elowsson, P; Norlén, K; Jakobson, S

    1998-08-01

    Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO). General hemodynamics and regional blood flows assessed by microsphere technique (15 microns) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H2O end-expiratory pressure (CPPV8) before and after intravenous administration of propanolol (0.3 mg.kg-1 followed by 0.15 mg.kg-1.h-1, n = 8) or verapamil (0.1 mg.kg-1 followed by 0.3 mg.kg-1.h-1, n = 8). CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase. The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.

  5. Cardiac output, O2 delivery and VO2 kinetics during step exercise in acute normobaric hypoxia.

    PubMed

    Lador, Frédéric; Tam, Enrico; Adami, Alessandra; Kenfack, Marcel Azabji; Bringard, Aurélien; Cautero, Michela; Moia, Christian; Morel, Denis R; Capelli, Carlo; Ferretti, Guido

    2013-04-01

    We hypothesised that phase II time constant (τ2) of alveolar O2 uptake ( [Formula: see text] ) is longer in hypoxia than in normoxia as a consequence of a parallel deceleration of the kinetics of O2 delivery ( [Formula: see text] ). To test this hypothesis, breath-by-breath [Formula: see text] and beat-by-beat [Formula: see text] were measured in eight male subjects (25.4±3.4yy, 1.81±0.05m, 78.8±5.7kg) at the onset of cycling exercise (100W) in normoxia and acute hypoxia ( [Formula: see text] ). Blood lactate ([La]b) accumulation during the exercise transient was also measured. The τ2 for [Formula: see text] was shorter than that for [Formula: see text] in normoxia (8.3±6.8s versus 17.8±3.1s), but not in hypoxia (31.5±21.7s versus 28.4 5.4±5.4s). [La]b was increased in the exercise transient in hypoxia (3.0±0.5mM at exercise versus 1.7±0.2mM at rest), but not in normoxia. We conclude that the slowing down of the [Formula: see text] kinetics generated the longer τ2 for [Formula: see text] in hypoxia, with consequent contribution of anaerobic lactic metabolism to the energy balance in exercise transient, witnessed by the increase in [La]b.

  6. Assessment of cardiac output from noninvasive determination of arterial pressure profile in subjects at rest.

    PubMed

    Antonutto, G; Girardis, M; Tuniz, D; Petri, E; Capelli, C

    1994-01-01

    The stroke volume of the left ventricle (SV) was calculated from noninvasive recordings of the arterial pressure using a finger photoplethysmograph and compared to the values obtained by pulsed Doppler echocardiography (PDE). A group of 19 healthy men and 12 women [mean ages: 20.8 (SD 1.6) and 22.2 (SD 1.6) years respectively] were studied at rest in the supine position. The ratio of the area below the ejection phase of the arterial pressure wave (A(s)) to SV, as obtained by PDE, yielded a "calibration factor" dimensionally equal to the hydraulic impedance of the system (Zao = A(s).SV-1). The Zao amounted on average to 0.062 (SD 0.018) mmHg.s.cm-3 for the men and to 0.104 (SD 0.024) mmHg.s.cm-3 for the women. The Zao was also estimated from the equation: Zao = a.(d + b.HR + c.PP + e.MAP)-1, where HR was the heart rate, PP the pulse pressure, MAP the mean arterial pressure and the coefficients of the equation were obtained by an iterating statistical package. The value of Zao thus obtained allowed the calculation of SV from measurements derived from the photoplethysmograph only. The mean percentage error between the SV thus obtained and those experimentally determined by PDE amounted to 14.8 and 15.6 for the men and the women, respectively. The error of the estimate was reduced to 12.3 and to 11.1, respectively, if the factor Zao, experimentally obtained from a given heart beat, was subsequently applied to other beats to obtain SV from the A(s) measurement in the same subject.

  7. Evaluation of a morphological filter in mean cardiac output determination: application to left ventricular assist devices.

    PubMed

    Stevens, Michael Charles; Bradley, Andrew P; Wilson, Stephen J; Mason, David Glen

    2013-08-01

    A morphological filter (MF) is presented for the determination of beat-to-beat mean rotary left ventricular assist device (LVAD) flow rate, measured using an implanted flow probe. The performance of this non-linear filter was assessed using LVAD flow rate (QLVAD) data sets obtained from in silico and in vivo sources. The MF was compared with a third-order Butterworth filter (BWF) and a 10-s moving average filter (MAF). Performance was assessed by calculating the response time and steady state error across a range of heart rates and levels of noise. The response time of the MF was 3.5 times faster than the MAF, 0.5 s slower than the BWF, and had a steady state error of 2.61 %. It completely removed pulsatile signal components caused by residual ventricular function, and tracked sharp transient changes in QLVAD better than the BWF. The use of a two-stage MF improved the noise immunity compared to the single-stage MF. This study showed that the good performance characteristics of the non-linear MF make it a more suitable candidate for embedded real-time processing of QLVAD than linear filters.

  8. Fetal cardiac ventricular volume, cardiac output, and ejection fraction determined with four-dimensional ultrasound using Spatio-Temporal Image Correlation (STIC) and Virtual Organ Computed-aided AnaLysis (VOCAL™)

    PubMed Central

    Hamill, Neil; Yeo, Lami; Romero, Roberto; Hassan, Sonia S.; Myers, Stephen A.; Mittal, Pooja; Kusanovic, Juan Pedro; Balasubramaniam, Mamtha; Chaiworapongsa, Tinnakorn; Vaisbuch, Edi; Espinoza, Jimmy; Gotsch, Francesca; Goncalves, Luis F.; Lee, Wesley

    2011-01-01

    Objective To quantify fetal cardiovascular parameters with Spatio-Temporal Image Correlation (STIC) and Virtual Organ Computed-aided AnaLysis (VOCAL™) utilizing the sub-feature: “Contour Finder: Trace”. Study Design A cross-sectional study was designed consisting of patients with normal pregnancies between 19 and 40 weeks of gestation. After STIC datasets were acquired, analysis was performed offline (4DView) and the following cardiovascular parameters were evaluated: ventricular volume in end systole and end diastole, stroke volume, cardiac output, and ejection fraction. To account for fetal size, cardiac output was also expressed as a function of head circumference, abdominal circumference, or femoral diaphysis length. Regression models were fitted for each cardiovascular parameter to assess the effect of gestational age and paired comparisons were made between the left and right ventricles. Results 1) Two hundred and seventeen patients were retrospectively identified, of whom 184 had adequate STIC datasets (85% acceptance); 2) ventricular volume, stroke volume, cardiac output, and adjusted cardiac output increased with gestational age; whereas, the ejection fraction decreased as gestation advanced; 3) the right ventricle was larger than the left in both systole (Right: 0.50 ml, IQR: 0.2 – 0.9; vs. Left: 0.27 ml, IQR: 0.1 – 0.5; p<0.001) and diastole (Right: 1.20 ml, IQR: 0.7 – 2.2; vs. Left: 1.03 ml, IQR: 0.5 – 1.7; p<0.001); 4) there were no differences between the left and right ventricle with respect to stroke volume, cardiac output, or adjusted cardiac output; and 5) the left ventricular ejection fraction was greater than the right (Left: 72.2%, IQR: 64 – 78; vs. Right: 62.4%, IQR: 56 – 69; p<0.001). Conclusion Fetal echocardiography, utilizing STIC and VOCAL™ with the sub-feature: “Contour Finder: Trace”, allows assessment of fetal cardiovascular parameters. Normal fetal cardiovascular physiology is characterized by ventricular

  9. Diesel Exhaust Inhalation Increases Cardiac Output, Bradyarrhythmias, and Parasympathetic Tone in Aged Heart Failure-Prone Rats

    EPA Science Inventory

    Acute air pollutant inhalation is linked to adverse cardiac events and death, and hospitalizations for heart failure. Diesel exhaust (DE) is a major air pollutant suspected to exacerbate preexisting cardiac conditions, in part, through autonomic and electrophysiologic disturbance...

  10. Diesel Exhaust Inhalation Increases Cardiac Output, Bradyarrhythmias, and Parasympathetic Tone in Aged Heart Failure-Prone Rats

    EPA Science Inventory

    Acute air pollutant inhalation is linked to adverse cardiac events and death, and hospitalizations for heart failure. Diesel exhaust (DE) is a major air pollutant suspected to exacerbate preexisting cardiac conditions, in part, through autonomic and electrophysiologic disturbance...

  11. [Two-dimensional pulsed Doppler echocardiographic estimates of cardiac output in man: sampling at the entrance to the main pulmonary artery].

    PubMed

    Kuwako, K; Sakuma, T; Matsuda, M; Sekiguchi, T; Sugishita, Y; Ito, I

    1984-12-01

    To assess the feasibility and accuracy of measuring cardiac outputs (CO) by two-dimensional (2-D) pulsed Doppler echocardiography, taking samples at the main pulmonary artery just beyond the pulmonary valve, 62 cardiac patients were studied. The results obtained were compared with CO values determined by the thermodilution technique. 2-D Doppler echocardiograms suitable for computing CO were recorded in 37 (60%) of 62 patients. A significant correlation (r = 0.64) was observed between 2-D echocardiographic and angiographic pulmonary ring diameters (PRD), but the echocardiographic PRD was smaller than that of angiography by 0.4 +/- 0.2 cm. Thus, to compute the Doppler CO, the echocardiographic PRD had to be corrected by the difference between the angiographic and echocardiographic PRD. The angle between the ultrasound beam and the pulmonary blood flow was 7.8 +/- 6.1 degrees (0 approximately 18 degrees), and this was negligible for computing the Doppler CO. Even in cases with atrial fibrillation, the Doppler CO could be computed as is done in sinus rhythm. The correlation between the thermodilution and Doppler CO was highly significant (r = 0.92), and the regression equation was as follows: Thermodilution CO = 1.09 X (Doppler CO)-0.19 The difference between thermodilution and Doppler CO was 3.4 +/- 10.0% (-21 approximately +21%). Comparing the differences in CO between the thermodilution and dye-dilution techniques, those between thermodilution and the Fick methods, and those among thermodilution methods reported in the literatures, the difference in this study was not large and was acceptable. Thus, measurement of CO by pulsed Doppler echocardiography, with sampling entrance to the main pulmonary artery, can be used clinically.

  12. Comparing the accuracy of ES-BC, EIS-GS, and ES Oxi on body composition, autonomic nervous system activity, and cardiac output to standardized assessments

    PubMed Central

    Lewis, John E; Tannenbaum, Stacey L; Gao, Jinrun; Melillo, Angelica B; Long, Evan G; Alonso, Yaima; Konefal, Janet; Woolger, Judi M; Leonard, Susanna; Singh, Prabjot K; Chen, Lawrence; Tiozzo, Eduard

    2011-01-01

    Background and purpose The Electro Sensor Complex (ESC) is software that combines three devices using bioelectrical impedance, galvanic skin response, and spectrophotometry: (1) ES-BC (Electro Sensor-Body Composition; LD Technology, Miami, FL) to assess body composition, (2) EIS-GS (Electro Interstitial Scan-Galvanic Skin; LD Technology) to predict autonomic nervous system activity, and (3) ES Oxi (Electro Sensor Oxi; LD Technology) to assess cardiac output. The objective of this study was to compare each to a standardized assessment: ES-BC to dual-energy X-ray absorptiometry (DXA), EIS-GS to heart rate variability, and ES Oxi to BioZ Dx Diagnostic System (BioZ Dx; SonoSite Inc, Bothell, WA). Patients and methods The study was conducted in two waves. Fifty subjects were assessed for body composition and autonomic nervous system activity. Fifty-one subjects were assessed for cardiac output. Results We found adequate relative and absolute agreement between ES-BC and DXA for fat mass (r = 0.97, P < 0.001) with ES-BC overestimating fat mass by 0.1 kg and for body fat percentage (r = 0.92, P < 0.001) with overestimation of fat percentage by 0.4%. For autonomic nervous system activity, we found marginal relative agreement between EIS-GS and heart rate variability by using EIS-GS as the predictor in a linear regression equation (adjusted R2 = 0.56, P = 0.03). For cardiac output, adequate relative and absolute agreement was found between ES Oxi and BioZ Dx at baseline (r = 0.60, P < 0.001), after the first exercise stage (r = 0.79, P < 0.001), and after the second exercise stage (r = 0.86, P < 0.001). Absolute agreement was found at baseline and after both bouts of exercise; ES Oxi overestimated baseline and stage 1 exercise cardiac output by 0.3 L/minute and 0.1 L/minute, respectively, but exactly estimated stage 2 exercise cardiac output. Conclusion ES-BC and ES Oxi accurately assessed body composition and cardiac output compared to standardized instruments, whereas EIS

  13. The 24 h pattern of arterial pressure in mice is determined mainly by heart rate‐driven variation in cardiac output

    PubMed Central

    Kurtz, Theodore W.; Lujan, Heidi L.; DiCarlo, Stephen E.

    2014-01-01

    Abstract Few studies have systematically investigated whether daily patterns of arterial blood pressure over 24 h are mediated by changes in cardiac output, peripheral resistance, or both. Understanding the hemodynamic mechanisms that determine the 24 h patterns of blood pressure may lead to a better understanding of how such patterns become disturbed in hypertension and influence risk for cardiovascular events. In conscious, unrestrained C57BL/6J mice, we investigated whether the 24 h pattern of arterial blood pressure is determined by variation in cardiac output, systemic vascular resistance, or both and also whether variations in cardiac output are mediated by variations in heart rate and or stroke volume. As expected, arterial pressure and locomotor activity were significantly (P < 0.05) higher during the nighttime period compared with the daytime period when mice are typically sleeping (+12.5 ± 1.0 mmHg, [13%] and +7.7 ± 1.3 activity counts, [254%], respectively). The higher arterial pressure during the nighttime period was mediated by higher cardiac output (+2.6 ± 0.3 mL/min, [26%], P < 0.05) in association with lower peripheral resistance (−1.5 ± 0.3 mmHg/mL/min, [−13%] P < 0.05). The increased cardiac output during the nighttime was mainly mediated by increased heart rate (+80.0 ± 16.5 beats/min, [18%] P < 0.05), as stroke volume increased minimally at night (+1.6 ± 0.5 μL per beat, [6%] P < 0.05). These results indicate that in C57BL/6J mice, the 24 h pattern of blood pressure is hemodynamically mediated primarily by the 24 h pattern of cardiac output which is almost entirely determined by the 24 h pattern of heart rate. These findings suggest that the differences in blood pressure between nighttime and daytime are mainly driven by differences in heart rate which are strongly correlated with differences in locomotor activity. PMID:25428952

  14. Registries to measure and improve outcomes after cardiac arrest.

    PubMed

    Goldberger, Zachary D; Nichol, Graham

    2013-06-01

    Cardiac arrest registries are used to measure and improve the process and outcome of resuscitation care, and can give insight into risk factors, prognosis, and the effectiveness of interventions to mitigate its impact. This review provides an overview of current out-of-hospital (OHCA) and in-hospital cardiac arrest (IHCA) registries, with attention to key recent findings and future directions. Major OHCA registries include the Resuscitation Outcomes Consortium Cardiac Arrest Epistry and Cardiac Arrest Registry to Enhance Survival. Registry data from IHCA largely stem from the US and Canada with Get with the Guidelines-Resuscitation, and the UK with the National Cardiac Arrest Audit. Each registry has strengths and limitations. Important findings include trends in survival, racial disparities in care, and hospital and community-level variations in performance, as well as estimates of the effectiveness of individual interventions. Utstein definitions facilitate uniform reporting of the process and outcome of care, and are currently being updated. Standardization of registry data is an ongoing challenge. OHCA and IHCA registries are invaluable in advancing our understanding of resuscitation care, as well as variations in international practice. Investigations that compare and contrast outcomes from established and evolving registries will help advance resuscitation science further.

  15. Input-output relations in biological systems: measurement, information and the Hill equation.

    PubMed

    Frank, Steven A

    2013-12-05

    Biological systems produce outputs in response to variable inputs. Input-output relations tend to follow a few regular patterns. For example, many chemical processes follow the S-shaped Hill equation relation between input concentrations and output concentrations. That Hill equation pattern contradicts the fundamental Michaelis-Menten theory of enzyme kinetics. I use the discrepancy between the expected Michaelis-Menten process of enzyme kinetics and the widely observed Hill equation pattern of biological systems to explore the general properties of biological input-output relations. I start with the various processes that could explain the discrepancy between basic chemistry and biological pattern. I then expand the analysis to consider broader aspects that shape biological input-output relations. Key aspects include the input-output processing by component subsystems and how those components combine to determine the system's overall input-output relations. That aggregate structure often imposes strong regularity on underlying disorder. Aggregation imposes order by dissipating information as it flows through the components of a system. The dissipation of information may be evaluated by the analysis of measurement and precision, explaining why certain common scaling patterns arise so frequently in input-output relations. I discuss how aggregation, measurement and scale provide a framework for understanding the relations between pattern and process. The regularity imposed by those broader structural aspects sets the contours of variation in biology. Thus, biological design will also tend to follow those contours. Natural selection may act primarily to modulate system properties within those broad constraints.

  16. Dynamic cardiac output regulation at rest, during exercise, and muscle metaboreflex activation: impact of congestive heart failure.

    PubMed

    Ichinose, Masashi; Sala-Mercado, Javier A; Coutsos, Matthew; Li, Zhenhua; Ichinose, Tomoko K; Dawe, Elizabeth; Fano, Dominic; O'Leary, Donal S

    2012-10-01

    We tested whether mild and moderate dynamic exercise and muscle metaboreflex activation (MMA) affect dynamic baroreflex control of heart rate (HR) and cardiac output (CO), and the influence of stroke volume (SV) fluctuations on CO regulation in normal (N) and pacing-induced heart failure (HF) dogs by employing transfer function analyses of the relationships between spontaneous changes in left ventricular systolic pressure (LVSP) and HR, LVSP and CO, HR and CO, and SV and CO at low and high frequencies (Lo-F, 0.04-0.15 Hz; Hi-F, 0.15-0.6 Hz). In N dogs, both workloads significantly decreased the gains for LVSP-HR and LVSP-CO in Hi-F, whereas only moderate exercise also reduced the LVSP-CO gain in Lo-F. MMA during mild exercise further decreased the gains for LVSP-HR in both frequencies and for LVSP-CO in Lo-F. MMA during moderate exercise further reduced LVSP-HR gain in Lo-F. Coherence for HR-CO in Hi-F was decreased by exercise and MMA, whereas that in Lo-F was sustained at a high level (>0.8) in all settings. HF significantly decreased dynamic HR and CO regulation in all situations. In HF, the coherence for HR-CO in Lo-F decreased significantly in all settings; the coherence for SV-CO in Lo-F was significantly higher. We conclude that dynamic exercise and MMA reduces dynamic baroreflex control of HR and CO, and these are substantially impaired in HF. In N conditions, HR modulation plays a major role in CO regulation. In HF, influence of HR modulation wanes, and fluctuations of SV dominate in CO variations.

  17. Cardiac output response to exercise in relation to metabolic demand in heart failure with preserved ejection fraction

    PubMed Central

    Abudiab, Muaz M.; Redfield, Margaret M.; Melenovsky, Vojtech; Olson, Thomas P.; Kass, David A.; Johnson, Bruce D.; Borlaug, Barry A.

    2013-01-01

    Aims Exercise intolerance is a hallmark of heart failure with preserved ejection fraction (HFpEF), yet its mechanisms remain unclear. The current study sought to determine whether increases in cardiac output (CO) during exercise are appropriately matched to metabolic demands in HFpEF. Methods and results Patients with HFpEF (n = 109) and controls (n = 73) exercised to volitional fatigue with simultaneous invasive (n = 96) or non-invasive (n = 86) haemodynamic assessment and expired gas analysis to determine oxygen consumption (VO2) during upright or supine exercise. At rest, HFpEF patients had higher LV filling pressures but similar heart rate, stroke volume, EF, and CO. During supine and upright exercise, HFpEF patients displayed lower peak VO2 coupled with blunted increases in heart rate, stroke volume, EF, and CO compared with controls. LV filling pressures increased dramatically in HFpEF patients, with secondary elevation in pulmonary artery pressures. Reduced peak VO2 in HFpEF patients was predominantly attributable to CO limitation, as the slope of the increase in CO relative to VO2 was 20% lower in HFpEF patients (5.9 ± 2.5 vs. 7.4 ± 2.6 L blood/L O2, P = 0.0005). While absolute increases in arterial–venous O2 difference with exercise were similar in HFpEF patients and controls, augmentation in arterial–venous O2 difference relative to VO2 was greater in HFpEF patients (8.9 ± 3.4 vs. 5.5 ± 2.0 min/dL, P < 0.0001). These differences were observed in the total cohort and when upright and supine exercise modalities were examined individually. Conclusion While diastolic dysfunction promotes congestion and pulmonary hypertension with stress in HFpEF, reduction in exercise capacity is predominantly related to inadequate CO relative to metabolic needs. PMID:23426022

  18. Dynamic cardiac output regulation at rest, during exercise, and muscle metaboreflex activation: impact of congestive heart failure

    PubMed Central

    Ichinose, Masashi; Sala-Mercado, Javier A.; Coutsos, Matthew; Li, ZhenHua; Ichinose, Tomoko K.; Dawe, Elizabeth; Fano, Dominic

    2012-01-01

    We tested whether mild and moderate dynamic exercise and muscle metaboreflex activation (MMA) affect dynamic baroreflex control of heart rate (HR) and cardiac output (CO), and the influence of stroke volume (SV) fluctuations on CO regulation in normal (N) and pacing-induced heart failure (HF) dogs by employing transfer function analyses of the relationships between spontaneous changes in left ventricular systolic pressure (LVSP) and HR, LVSP and CO, HR and CO, and SV and CO at low and high frequencies (Lo-F, 0.04–0.15 Hz; Hi-F, 0.15–0.6 Hz). In N dogs, both workloads significantly decreased the gains for LVSP-HR and LVSP-CO in Hi-F, whereas only moderate exercise also reduced the LVSP-CO gain in Lo-F. MMA during mild exercise further decreased the gains for LVSP-HR in both frequencies and for LVSP-CO in Lo-F. MMA during moderate exercise further reduced LVSP-HR gain in Lo-F. Coherence for HR-CO in Hi-F was decreased by exercise and MMA, whereas that in Lo-F was sustained at a high level (>0.8) in all settings. HF significantly decreased dynamic HR and CO regulation in all situations. In HF, the coherence for HR-CO in Lo-F decreased significantly in all settings; the coherence for SV-CO in Lo-F was significantly higher. We conclude that dynamic exercise and MMA reduces dynamic baroreflex control of HR and CO, and these are substantially impaired in HF. In N conditions, HR modulation plays a major role in CO regulation. In HF, influence of HR modulation wanes, and fluctuations of SV dominate in CO variations. PMID:22855278

  19. Plasma volume expansion does not increase maximal cardiac output or VO2 max in lowlanders acclimatized to altitude.

    PubMed

    Calbet, José A L; Rådegran, Göran; Boushel, Robert; Søndergaard, Hans; Saltin, Bengt; Wagner, Peter D

    2004-09-01

    With altitude acclimatization, blood hemoglobin concentration increases while plasma volume (PV) and maximal cardiac output (Qmax) decrease. This investigation aimed to determine whether reduction of Qmax at altitude is due to low circulating blood volume (BV). Eight Danish lowlanders (3 females, 5 males: age 24.0 +/- 0.6 yr; mean +/- SE) performed submaximal and maximal exercise on a cycle ergometer after 9 wk at 5,260 m altitude (Mt. Chacaltaya, Bolivia). This was done first with BV resulting from acclimatization (BV = 5.40 +/- 0.39 liters) and again 2-4 days later, 1 h after PV expansion with 1 liter of 6% dextran 70 (BV = 6.32 +/- 0.34 liters). PV expansion had no effect on Qmax, maximal O2 consumption (VO2), and exercise capacity. Despite maximal systemic O2 transport being reduced 19% due to hemodilution after PV expansion, whole body VO2 was maintained by greater systemic O2 extraction (P < 0.05). Leg blood flow was elevated (P < 0.05) in hypervolemic conditions, which compensated for hemodilution resulting in similar leg O2 delivery and leg VO2 during exercise regardless of PV. Pulmonary ventilation, gas exchange, and acid-base balance were essentially unaffected by PV expansion. Sea level Qmax and exercise capacity were restored with hyperoxia at altitude independently of BV. Low BV is not a primary cause for reduction of Qmax at altitude when acclimatized. Furthermore, hemodilution caused by PV expansion at altitude is compensated for by increased systemic O2 extraction with similar peak muscular O2 delivery, such that maximal exercise capacity is unaffected.

  20. Steep fall in cardiac output is main determinant of hypotension during drug-free and nitroglycerine-induced orthostatic vasovagal syncope.

    PubMed

    Verheyden, Bart; Liu, Jiexin; van Dijk, Nynke; Westerhof, Berend E; Reybrouck, Tony; Aubert, André E; Wieling, Wouter

    2008-12-01

    How much of the hypotension occurring during postural syncope is cardiac output-mediated and how much can be ascribed to a fall in systemic vascular resistance are unknown. The contribution of both determinants may be influenced by the use of vasoactive drugs. The purpose of this study was to assess the determinants of hypotension during drug-free and nitroglycerine (NTG)-induced vasovagal presyncope in routine tilt table testing. In this retrospective study, a total of 56 patients (37 female; age 36 +/- 19 years) with suspected vasovagal syncope and a positive tilt test at two clinical centers were selected. In 29 patients, presyncope was provoked by 0.4 mg sublingual NTG, administered in the 60 degrees head-up tilt position. In the other 27 patients, presyncope was provoked by passive tilt alone. Finger arterial pressure was monitored continuously, and left ventricular stroke volume was computed from pressure pulsations. After NTG administration, heart rate rose, and peak heart rate was similar in all patients. Use of NTG did not affect circulatory patterns precipitating a vasovagal response. On average in all patients, marked hypotension was mediated by an approximately 50% fall in cardiac output, whereas systemic vascular resistance was well maintained until presyncope. Hypotension during routine tilt testing is cardiac output-mediated, and the mechanism appears independent of the use of 0.4 mg sublingual NTG. The study data challenge the conventional idea of systemic vasodilation as the overriding cause of hypotension during postural syncope.

  1. Measuring hospital efficiency with Data Envelopment Analysis: nonsubstitutable vs. substitutable inputs and outputs.

    PubMed

    Barnum, Darold T; Walton, Surrey M; Shields, Karen L; Schumock, Glen T

    2011-12-01

    There is a conflict between Data Envelopment Analysis (DEA) theory's requirement that inputs (outputs) be substitutable, and the ubiquitous use of nonsubstitutable inputs and outputs in DEA applications to hospitals. This paper develops efficiency indicators valid for nonsubstitutable variables. Then, using a sample of 87 community hospitals, it compares the new measures' efficiency estimates with those of conventional DEA measures. DEA substantially overestimated the hospitals' efficiency on the average, and reported many inefficient hospitals to be efficient. Further, it greatly overestimated the efficiency of some hospitals but only slightly overestimated the efficiency of others, thus making any comparisons among hospitals questionable. These results suggest that conventional DEA models should not be used to estimate the efficiency of hospitals unless there is empirical evidence that the inputs (outputs) are substitutable. If inputs (outputs) are not substitutes, efficiency indicators valid for nonsubstitutability should be employed, or, before applying DEA, the nonsubstitutable variables should be combined using an appropriate weighting scheme or statistical methodology.

  2. High-sensitive cardiac troponin T measurements in prediction of non-cardiac complications after major abdominal surgery.

    PubMed

    Noordzij, P G; van Geffen, O; Dijkstra, I M; Boerma, D; Meinders, A J; Rettig, T C D; Eefting, F D; van Loon, D; van de Garde, E M W; van Dongen, E P A

    2015-06-01

    Postoperative non-cardiac complication rates are as high as 11-28% after high-risk abdominal procedures. Emerging evidence indicates that postoperative cardiac troponin T elevations are associated with adverse outcome in non-cardiac surgery. The aim of this study was to determine the relationship between postoperative high-sensitive cardiac troponin T elevations and non-cardiac complications in patients after major abdominal surgery. This prospective observational single-centre cohort study included patients at risk for coronary artery disease undergoing elective major abdominal surgery. Cardiac troponin was measured before surgery and at day 1, 3, and 7. Multivariable logistic regression analysis was performed to examine the adjusted association for different cut-off concentrations of postoperative myocardial injury and non-cardiac outcome. In 203 patients, 690 high-sensitive cardiac troponin T measurements were performed. Fifty-three patients (26%) had a non-cardiac complication within 30 days after surgery. Hospital mortality was 4% (8/203). An increase in cardiac troponin T concentration ≥100% compared with baseline was a superior independent predictor of non-cardiac postoperative clinical complications (adjusted odds ratio 4.3, 95% confidence interval 1.8-10.1, P<0.001) and was associated with increased length of stay (9 days, 95% confidence interval 7-11 vs 7 days, 95% confidence interval 6-8, P=0.004) and increased hospital mortality (12 vs 2%, P=0.028). A postoperative high-sensitive cardiac troponin T increase ≥100% is a strong predictor of non-cardiac 30 day complications, increased hospital stay and hospital mortality in patients undergoing major abdominal surgery. NCT02150486. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. The effect of small field output factor measurements on IMRT dosimetry

    SciTech Connect

    Azimi, Rezvan; Alaei, Parham; Higgins, Patrick

    2012-08-15

    Purpose: To evaluate how changes in the measured small field output factors affect the doses in intensity-modulated treatment planning. Methods: IMRT plans were created using Philips Pinnacle treatment planning system. The plans were optimized to treat a cylindrical target 2 cm in diameter and 2 cm in length. Output factors for 2 Multiplication-Sign 2 and 3 Multiplication-Sign 3 cm{sup 2} field sizes were changed by {+-}5%, {+-}10%, and {+-}20% increments from the baseline measurements and entered into the planning system. The treatment units were recommissioned in the treatment planning system after each modification of the output factors and treatment plans were reoptimized. All plans were delivered to a solid water phantom and dose measurements were made using an ionization chamber. The percentage differences between measured and computed doses were calculated. An Elekta Synergy and a Varian 2300CD linear accelerator were separately evaluated. Results: For the Elekta unit, decreasing the output factors resulted in higher measured than computed doses by 0.8% for -5%, 3.6% for -10%, and 8.7% for -20% steps. Increasing the output factors resulted in lower doses by 2.9% for +5%, 5.4% for +10%, and 8.3% for +20% steps. For the Varian unit no changes were observed for either increased or decreased output factors. Conclusions: The measurement accuracy of small field output factors are of importance especially when the treatment plan consists of small segments as in IMRT. The method proposed here could be used to verify the accuracy of the measured small field output factors for certain linear accelerators as well as to test the beam model. The Pinnacle treatment planning system model uses output factors as a function of jaw setting. Consequently, plans using the Elekta unit, which conforms the jaws to the segments, are sensitive to small field measurement accuracy. On the other hand, for the Varian unit, jaws are fixed and segments are modeled as blocked fields hence

  4. Continuous registration of blood velocity and cardiac output with a hot-film anemometer probe, mounted on a Swan-Ganz thermodilution catheter.

    PubMed

    Paulsen, P K; Andersen, M

    1981-01-01

    In order to construct a catheter, capable of monitoring cardiac output, a specially designed double-conical hot-film anemometer probe was fastened at the tip of a Swan-Ganz thermodilution catheter. Common sources of error for most catheter velocity probes include difficult calibration, unknown velocity profile at the point of measurement and unknown position of the probe in this profile. By using mongrel dogs and in order to exclude these sources of error, the intermittent thermodilution method was used to in vitro calibrate the hot-film anemometer, which registered velocity continuously. A mean correlation coefficient between these two methods was found to be 0.886. A mean line of regression between thermodilution (abscissa) and anemometer (ordinate) had a slope of 0.796 +/- 0.223 (+/- SD) and a y-intercept of 24 +/- 14 ml/min/kg. The slope was significantly lower than one (t test, p less than 0.05) and the y-intercept significantly larger than zero (t test, p less than 0.02). As a control of the thermodilution method, electromagnetic flow in the ascending aorta was registered and a mean correlation coefficient of 0.967 found. The hot-film sensor itself can be used as thermodilution method with the hot-film anemometer's continuous registration of velocity.

  5. Scale-Independent Measures and Pathologic Cardiac Dynamics

    NASA Astrophysics Data System (ADS)

    Amaral, Luís A.; Goldberger, Ary L.; Ivanov, Plamen Ch.; Stanley, H. Eugene

    1998-09-01

    We study several scale-independent measures of cardiac interbeat interval dynamics defined through the application of the wavelet transform. We test their performance in detecting heart disease using a database consisting of records of interbeat intervals for a group of healthy individuals and subjects with congestive heart failure. We find that scale-independent measures effectively distinguish healthy from pathologic behavior and propose a new two-variable scale-independent measure that could be clinically useful. We compare the performance of a recently proposed scale-dependent measure and find that the results depend on the database analyzed and on the analyzing wavelet.

  6. Technical Note: PRESAGE three-dimensional dosimetry accurately measures Gamma Knife output factors

    PubMed Central

    Klawikowski, Slade J.; Yang, James N.; Adamovics, John; Ibbott, Geoffrey S.

    2014-01-01

    Small-field output factor measurements are traditionally very difficult because of steep dose gradients, loss of lateral electronic equilibrium, and dose volume averaging in finitely sized detectors. Three-dimensional (3D) dosimetry is ideal for measuring small output factors and avoids many of these potential challenges of point and two-dimensional detectors. PRESAGE 3D polymer dosimeters were used to measure the output factors for the 4 mm and 8 mm collimators of the Leksell Perfexion Gamma Knife radiosurgery treatment system. Discrepancies between the planned and measured distance between shot centers were also investigated. A Gamma Knife head frame was mounted onto an anthropomorphic head phantom. Special inserts were machined to hold 60 mm diameter, 70 mm tall cylindrical PRESAGE dosimeters. The phantom was irradiated with one 16 mm shot and either one 4 mm or one 8 mm shot, to a prescribed dose of either 3 Gy or 4 Gy to the 50% isodose line. The two shots were spaced between 30 mm and 60 mm apart and aligned along the central axis of the cylinder. The Presage dosimeters were measured using the DMOS-RPC optical CT scanning system. Five independent 4 mm output factor measurements fell within 2% of the manufacturer’s Monte Carlo simulation-derived nominal value, as did two independent 8 mm output factor measurements. The measured distances between shot centers varied by ± 0.8 mm with respect to the planned shot displacements. On the basis of these results, we conclude that PRESAGE dosimetry is excellently suited to quantify the difficult-to-measure Gamma Knife output factors. PMID:25368961

  7. Quantum theory of multiple-input-multiple-output Markovian feedback with diffusive measurements

    NASA Astrophysics Data System (ADS)

    Chia, A.; Wiseman, H. M.

    2011-07-01

    Feedback control engineers have been interested in multiple-input-multiple-output (MIMO) extensions of single-input-single-output (SISO) results of various kinds due to its rich mathematical structure and practical applications. An outstanding problem in quantum feedback control is the extension of the SISO theory of Markovian feedback by Wiseman and Milburn [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.70.548 70, 548 (1993)] to multiple inputs and multiple outputs. Here we generalize the SISO homodyne-mediated feedback theory to allow for multiple inputs, multiple outputs, and arbitrary diffusive quantum measurements. We thus obtain a MIMO framework which resembles the SISO theory and whose additional mathematical structure is highlighted by the extensive use of vector-operator algebra.

  8. A Theoretical Framework for Educational Output Measurement. AIR Forum Paper 1978.

    ERIC Educational Resources Information Center

    Reece, William S.

    Construction of a theoretical measure of educational output is attempted in this paper. The effort begins by specifying the purpose for which this measure is intended: centralized allocation, according to the equimarginal principle, of limited resources to alternative units producing education. It then specifies a simple and narrow goal that…

  9. Input-output relations in biological systems: measurement, information and the Hill equation

    PubMed Central

    2013-01-01

    Biological systems produce outputs in response to variable inputs. Input-output relations tend to follow a few regular patterns. For example, many chemical processes follow the S-shaped Hill equation relation between input concentrations and output concentrations. That Hill equation pattern contradicts the fundamental Michaelis-Menten theory of enzyme kinetics. I use the discrepancy between the expected Michaelis-Menten process of enzyme kinetics and the widely observed Hill equation pattern of biological systems to explore the general properties of biological input-output relations. I start with the various processes that could explain the discrepancy between basic chemistry and biological pattern. I then expand the analysis to consider broader aspects that shape biological input-output relations. Key aspects include the input-output processing by component subsystems and how those components combine to determine the system’s overall input-output relations. That aggregate structure often imposes strong regularity on underlying disorder. Aggregation imposes order by dissipating information as it flows through the components of a system. The dissipation of information may be evaluated by the analysis of measurement and precision, explaining why certain common scaling patterns arise so frequently in input-output relations. I discuss how aggregation, measurement and scale provide a framework for understanding the relations between pattern and process. The regularity imposed by those broader structural aspects sets the contours of variation in biology. Thus, biological design will also tend to follow those contours. Natural selection may act primarily to modulate system properties within those broad constraints. Reviewers This article was reviewed by Eugene Koonin, Georg Luebeck and Sergei Maslov. PMID:24308849

  10. Nexfin noninvasive continuous hemodynamic monitoring: validation against continuous pulse contour and intermittent transpulmonary thermodilution derived cardiac output in critically ill patients.

    PubMed

    Ameloot, Koen; Van De Vijver, Katrijn; Broch, Ole; Van Regenmortel, Niels; De Laet, Inneke; Schoonheydt, Karen; Dits, Hilde; Bein, Berthold; Malbrain, Manu L N G

    2013-01-01

    Nexfin (Bmeye, Amsterdam, Netherlands) is a noninvasive cardiac output (CO) monitor based on finger arterial pulse contour analysis. The aim of this study was to validate Nexfin CO (NexCO) against thermodilution (TDCO) and pulse contour CO (CCO) by PiCCO (Pulsion Medical Systems, Munich, Germany). In a mix of critically ill patients (n = 45), NexCO and CCO were measured continuously and recorded at 2-hour intervals during the 8-hour study period. TDCO was measured at 0-4-8 hrs. NexCO showed a moderate to good (significant) correlation with TDCO (R (2) 0.68, P < 0.001) and CCO (R (2) 0.71, P < 0.001). Bland and Altman analysis comparing NexCO with TDCO revealed a bias (± limits of agreement, LA) of 0.4 ± 2.32 L/min (with 36% error) while analysis comparing NexCO with CCO showed a bias (±LA) of 0.2 ± 2.32 L/min (37% error). NexCO is able to follow changes in TDCO and CCO during the same time interval (level of concordance 89.3% and 81%). Finally, polar plot analysis showed that trending capabilities were acceptable when changes in NexCO (ΔNexCO) were compared to ΔTDCO and ΔCCO (resp., 89% and 88.9% of changes were within the level of 10% limits of agreement). we found a moderate to good correlation between CO measurements obtained with Nexfin and PiCCO.

  11. Nexfin Noninvasive Continuous Hemodynamic Monitoring: Validation against Continuous Pulse Contour and Intermittent Transpulmonary Thermodilution Derived Cardiac Output in Critically Ill Patients

    PubMed Central

    Van De Vijver, Katrijn; De laet, Inneke; Schoonheydt, Karen; Dits, Hilde; Bein, Berthold; Malbrain, Manu L. N. G.

    2013-01-01

    Introduction. Nexfin (Bmeye, Amsterdam, Netherlands) is a noninvasive cardiac output (CO) monitor based on finger arterial pulse contour analysis. The aim of this study was to validate Nexfin CO (NexCO) against thermodilution (TDCO) and pulse contour CO (CCO) by PiCCO (Pulsion Medical Systems, Munich, Germany). Patients and Methods. In a mix of critically ill patients (n = 45), NexCO and CCO were measured continuously and recorded at 2-hour intervals during the 8-hour study period. TDCO was measured at 0–4–8 hrs. Results. NexCO showed a moderate to good (significant) correlation with TDCO (R2 0.68, P < 0.001) and CCO (R2 0.71, P < 0.001). Bland and Altman analysis comparing NexCO with TDCO revealed a bias (± limits of agreement, LA) of 0.4 ± 2.32 L/min (with 36% error) while analysis comparing NexCO with CCO showed a bias (±LA) of 0.2 ± 2.32 L/min (37% error). NexCO is able to follow changes in TDCO and CCO during the same time interval (level of concordance 89.3% and 81%). Finally, polar plot analysis showed that trending capabilities were acceptable when changes in NexCO (ΔNexCO) were compared to ΔTDCO and ΔCCO (resp., 89% and 88.9% of changes were within the level of 10% limits of agreement). Conclusion. we found a moderate to good correlation between CO measurements obtained with Nexfin and PiCCO. PMID:24319373

  12. The effect of intermittent intraabdominal pressure elevations and low cardiac output on the femoral to carotid arterial blood pressure difference in piglets.

    PubMed

    Aksakal, Devrim; Hückstädt, Thomas; Richter, Steffen; Klitscher, Daniela; Wowra, Tobias; Schier, Felix; Wessel, Lucas M; Kubiak, Rainer

    2016-11-01

    Our previous work in a laparoscopic setting in piglets revealed that the systolic femoral artery pressure was approximately 5 % higher than its carotid counterpart, whereas the mean and diastolic values showed no significant difference. This remained idem when the intraabdominal pressure (IAP) was gradually increased. In this study, we aimed to investigate the effect of (1) intermittent IAP elevations and (2) a low cardiac output (CO) on the blood pressure (BP) difference cranially (carotid artery) and caudally (femoral artery) of a capnoperitoneum (ΔP = P a fem-P a carot). A total of twenty-two piglets (mean body weight 11.0 kg; range 8.9-13.3 kg) were studied. Of these, 14 underwent intermittent IAP elevations at 8 and 16 mmHg, and ΔP was measured. In another 8 piglets, a model of reduced CO was created by introducing an air embolism (2 ml/kg over 30 s) in the inferior caval vein (VCI) at 12 mmHg IAP to further assess the influence of this variable on ΔP. Systolic ΔP remained at a mean of 5.6 mmHg and was not significantly affected by insufflation or exsufflation up to an IAP of 16 mmHg. Diastolic and mean values showed no differences between P a carot and P a fem. P a fem, systol remained higher than its carotid counterpart as long as the cardiac index (CI) was above 1.5 l/min/m(2), but fell significantly below P a carot, systol at a low CI. There was no CO-dependent effect on diastolic and mean ΔP. Repeated IAP elevations do not significantly influence ΔP. Intermittent IAP elevations do not significantly influence ΔP. Despite of a CO-dependent inversion of systolic ΔP, mean BP measurements at the leg during laparoscopy remain representative even at low CO values.

  13. Measurement of dynamic gas disengagement profile by using an analog output level gauge

    NASA Astrophysics Data System (ADS)

    Mikkilineni, S.; Koelle, M.; Xu, H.

    The dynamic gas disengagement profile was measured in a 0.14 m diameter and 3.66 m high plexiglas column by using an analog output gauge, which was connected to a data acquisition system. This analog output gauge is a high accuracy continuous measurement level gauge. It is made up of a wave guide, a float, a motion or stress sensing device and a probe housing. The fluid level at any gas velocity is obtained by using the data acquisition system. The dynamic gas disengagement profile produced one slope in the bubble flow and two slopes in the churn turbulent flow representing unimodal and bimodal distributions of bubbles.

  14. Optimal Tracking Control of Unknown Discrete-Time Linear Systems Using Input-Output Measured Data.

    PubMed

    Kiumarsi, Bahare; Lewis, Frank L; Naghibi-Sistani, Mohammad-Bagher; Karimpour, Ali

    2015-12-01

    In this paper, an output-feedback solution to the infinite-horizon linear quadratic tracking (LQT) problem for unknown discrete-time systems is proposed. An augmented system composed of the system dynamics and the reference trajectory dynamics is constructed. The state of the augmented system is constructed from a limited number of measurements of the past input, output, and reference trajectory in the history of the augmented system. A novel Bellman equation is developed that evaluates the value function related to a fixed policy by using only the input, output, and reference trajectory data from the augmented system. By using approximate dynamic programming, a class of reinforcement learning methods, the LQT problem is solved online without requiring knowledge of the augmented system dynamics only by measuring the input, output, and reference trajectory from the augmented system. We develop both policy iteration (PI) and value iteration (VI) algorithms that converge to an optimal controller that require only measuring the input, output, and reference trajectory data. The convergence of the proposed PI and VI algorithms is shown. A simulation example is used to verify the effectiveness of the proposed control scheme.

  15. Measuring cardiac autonomic nervous system (ANS) activity in children.

    PubMed

    van Dijk, Aimée E; van Lien, René; van Eijsden, Manon; Gemke, Reinoud J B J; Vrijkotte, Tanja G M; de Geus, Eco J

    2013-04-29

    The autonomic nervous system (ANS) controls mainly automatic bodily functions that are engaged in homeostasis, like heart rate, digestion, respiratory rate, salivation, perspiration and renal function. The ANS has two main branches: the sympathetic nervous system, preparing the human body for action in times of danger and stress, and the parasympathetic nervous system, which regulates the resting state of the body. ANS activity can be measured invasively, for instance by radiotracer techniques or microelectrode recording from superficial nerves, or it can be measured non-invasively by using changes in an organ's response as a proxy for changes in ANS activity, for instance of the sweat glands or the heart. Invasive measurements have the highest validity but are very poorly feasible in large scale samples where non-invasive measures are the preferred approach. Autonomic effects on the heart can be reliably quantified by the recording of the electrocardiogram (ECG) in combination with the impedance cardiogram (ICG), which reflects the changes in thorax impedance in response to respiration and the ejection of blood from the ventricle into the aorta. From the respiration and ECG signals, respiratory sinus arrhythmia can be extracted as a measure of cardiac parasympathetic control. From the ECG and the left ventricular ejection signals, the preejection period can be extracted as a measure of cardiac sympathetic control. ECG and ICG recording is mostly done in laboratory settings. However, having the subjects report to a laboratory greatly reduces ecological validity, is not always doable in large scale epidemiological studies, and can be intimidating for young children. An ambulatory device for ECG and ICG simultaneously resolves these three problems. Here, we present a study design for a minimally invasive and rapid assessment of cardiac autonomic control in children, using a validated ambulatory device (1-5), the VU University Ambulatory Monitoring System (VU

  16. The effect of head up tilting on bioreactance cardiac output and stroke volume readings using suprasternal transcutaneous Doppler as a control in healthy young adults.

    PubMed

    Zhang, Jie; Critchley, Lester A H; Lee, Daniel C W; Khaw, Kim S; Lee, Shara W Y

    2016-10-01

    To compare the performance of a bioreactance cardiac output (CO) monitor (NICOM) and transcutaneous Doppler (USCOM) during head up tilting (HUT). Healthy young adult subjects, age 22 ± 1 years, 7 male and 7 female, were tilted over 3-5 s from supine to 70° HUT, 30° HUT and back to supine. Positions were held for 3 min. Simultaneous readings of NICOM and USCOM were performed 30 s into each new position. Mean blood pressure (MBP), heart rate (HR), CO and stroke volume (SV), and thoracic fluid content (TFC) were recorded. Bland-Altman, percentage changes and analysis of variance for repeated measures were used for statistical analysis. Pre-tilt NICOM CO and SV readings (6.1 ± 1.0 L/min and 113 ± 25 ml) were higher than those from USCOM (4.1 ± 0.6 L/min and 77 ± 9 ml) (P < 0.001). Bland-Altman limits of agreement for CO were wide with a percentage error of 38 %. HUT increased MBP and HR (P < 0.001). CO and SV readings decreased with HUT. However, the percentage changes in USCOM and NICOM readings did not concur (P < 0.001). Whereas USCOM provided gravitational effect proportional changes in SV readings of 23 ± 15 % (30° half tilt) and 44 ± 11 % (70° near full tilt), NICOM changes did not being 28 ± 10 and 33 ± 11 %. TFC decreased linearly with HUT. The NICOM does not provide linear changes in SV as predicted by physiology when patients are tilted. Furthermore there is a lack of agreement with USCOM measurements at baseline and during tilting.

  17. SU-E-T-257: Output Constancy: Reducing Measurement Variations in a Large Practice Group

    SciTech Connect

    Hedrick, K; Fitzgerald, T; Miller, R

    2014-06-01

    Purpose: To standardize output constancy check procedures in a large medical physics practice group covering multiple sites, in order to identify and reduce small systematic errors caused by differences in equipment and the procedures of multiple physicists. Methods: A standardized machine output constancy check for both photons and electrons was instituted within the practice group in 2010. After conducting annual TG-51 measurements in water and adjusting the linac to deliver 1.00 cGy/MU at Dmax, an acrylic phantom (comparable at all sites) and PTW farmer ion chamber are used to obtain monthly output constancy reference readings. From the collected charge reading, measurements of air pressure and temperature, and chamber Ndw and Pelec, a value we call the Kacrylic factor is determined, relating the chamber reading in acrylic to the dose in water with standard set-up conditions. This procedure easily allows for multiple equipment combinations to be used at any site. The Kacrylic factors and output results from all sites and machines are logged monthly in a central database and used to monitor trends in calibration and output. Results: The practice group consists of 19 sites, currently with 34 Varian and 8 Elekta linacs (24 Varian and 5 Elekta linacs in 2010). Over the past three years, the standard deviation of Kacrylic factors measured on all machines decreased by 20% for photons and high energy electrons as systematic errors were found and reduced. Low energy electrons showed very little change in the distribution of Kacrylic values. Small errors in linac beam data were found by investigating outlier Kacrylic values. Conclusion: While the use of acrylic phantoms introduces an additional source of error through small differences in depth and effective depth, the new standardized procedure eliminates potential sources of error from using many different phantoms and results in more consistent output constancy measurements.

  18. Association Between End-Tidal Carbon Dioxide Pressure and Cardiac Output During Fluid Expansion in Operative Patients Depend on the Change of Oxygen Extraction.

    PubMed

    Guinot, Pierre-Grégoire; Guilbart, Mathieu; Hchikat, Abdel Hakim; Trujillo, Marie; Huette, Pierre; Bar, Stéphane; Kirat, Kahina; Bernard, Eugénie; Dupont, Hervé; Lorne, Emmanuel

    2016-04-01

    In a model of hemorrhagic shock, end-tidal carbon dioxide tension (EtCO2) has been shown to reflect the dependence of oxygen delivery (DO2) and oxygen consumption (VO2) at the onset of shock. The objectives of the present study were to determine whether variations in EtCO2 during volume expansion (VE) are correlated with changes in oxygen extraction (O2ER) and whether EtCO2 has predictive value in this respect.All patients undergoing cardiac surgery admitted to intensive care unit in whom the physician decided to perform VE were included. EtCO2, cardiac output (CO), blood gas levels, and mean arterial pressure (MAP) were measured before and after VE with 500 mL of lactated Ringer solution. DO2, VO2, and O2ER were calculated from the central arterial and venous blood gas parameters. EtCO2 responders were defined as patients with more than a 4% increase in EtCO2 after VE. A receiver-operating characteristic curve was established for EtCO2, with a view to predicting a variation of more than 10% in O2ER.Twenty-two (43%) of the 51 included patients were EtCO2 responders. In EtCO2 nonresponders, VE increased MAP and CO. In EtCO2 responders, VE increased MAP, CO, EtCO2, and decreased O2ER. Changes in EtCO2 were correlated with changes in CO and O2ER during VE (P < 0.05). The variation of EtCO2 during VE predicted a decrease of over 10% in O2ER (area under the curve [95% confidence interval]: 0.88 [0.77-0.96]; P < 0.0001).During VE, an increase in EtCO2 did not systematically reflect an increase in CO. Only patients with a high O2ER (i.e., low ScvO2 values) display an increase in EtCO2. EtCO2 changes during fluid challenge predict changes in O2ER.

  19. A particle image velocimeter for measuring the output of high energy detonators

    SciTech Connect

    Murphy, Michael J; Adrian, Ronald J; Clarke, Steven A

    2010-01-01

    Results from feasibility experiments are presented to confirm that tracer-particle motion resulting from mass-velocity fields created by driving high-energy detonator output into dynamic witness plates can be successfully measured using particle image velocimetry (PIV). Experimental results, application challenges, and PIV system development are presented. In shock mechanics research, the ability to quantitatively measure the state of compression of shocked materials in two and three dimensions based on particle tracer methods is of extreme importance since such measurements provide precise temporal snapshots of two and three-dimensional shock-induced velocity fields. This is especially true in the science of detonation physics where such measurements provide enormous insight into fundamental. questions for understanding shock-loading processes, effects of shock-front curvature, and mechanisms of energy conversion from stimulus to shock output. As an example, answering such questions is paramount to the understanding and development of newer, safer detonators. To date, few attempts have been made to develop and implement standard particle tracer techniques to measure shock-induced flows resulting from explosive devices. The experimental challenge lies in developing a methodology wherein a tracer particle's inertia does not hinder its ability to accurately move with the rapidly changing flow field. We have recently developed the ability to characterize the output of unloaded explosive initiators (e.g. exploding bridge wires, exploding foils, laser-driven plasmas, etc.) using an optically-based diagnostic consisting of an ultra-high speed, time-resolved PIV system and inert, transparent polymers serving as dynamic witness plates. Initiator output is directed into a witness plate, and measurements of shock and mass velocities are made in a two-dimensional plane aligned with the initiator centerline. The results allow initiator output to be quantified in any in

  20. Exercise capacity in patients supported with rotary blood pumps is improved by a spontaneous increase of pump flow at constant pump speed and by a rise in native cardiac output.

    PubMed

    Jacquet, Luc; Vancaenegem, Olivier; Pasquet, Agnès; Matte, Pascal; Poncelet, Alain; Price, Joel; Gurné, Olivier; Noirhomme, Philippe

    2011-07-01

    Exercise capacity is improved in patients supported with continuous flow rotary blood pumps (RP). The aim of this study was to investigate the mechanisms underlying this improvement. Ten patients implanted with a RP underwent cardiopulmonary exercise testing (CPET) at 6 months after surgery with hemodynamic and metabolic measurements (RP group). A group of 10 matched heart failure patients were extracted from our heart transplant database, and the results of their last CPET before transplantation were used for comparison (heart failure [HF] group). Peak VO(2) was significantly higher in RP than in HF patients (15.8 ± 6.2 vs. 10.9 ± 3 mL O(2)/kg.min) reaching 52 ± 16% of their predicted peak VO(2). The total output measured by a Swan-Ganz catheter increased from 5.6 ± 1.6 to 9.2 ± 1.8 L/min in the RP group and was significantly higher at rest and at peak exercise than in the HF group, whose output increased from 3.5 ± 0.4 to 5.6 ± 1.6 L/min. In the RP group, the estimated pump flow increased from 5.3 ± 0.4 to 6.2 ± 0.8, whereas the native cardiac output increased from 0.0 ± 0.5 to 3 ± 1.7 L/min. Cardiac output at peak exercise was inversely correlated with age (r = -0.86, P = 0.001) and mean pulmonary artery pressure (r = -0.75, P = 0.012). Maximal exercise capacity is improved in patients supported by RP as compared to matched HF patients and reaches about 50% of the expected values. Both a spontaneous increase of pump flow at constant pump speed and an increase of the native cardiac output contribute to total flow elevation. These findings may suggest that an automatic pump speed adaptation during exercise would further improve the exercise capacity. This hypothesis should be examined.

  1. Application of the flow convergence region method to the determination of stroke volume and cardiac output in patients with mitral stenosis.

    PubMed

    Horibe, N; Matsumoto, M; Deng, Y B

    1996-04-01

    This study was undertaken to investigate the feasibility and accuracy of determination of stroke volume and cardiac output by calculating transmitral flow volume using the flow convergence region method in patients with mitral stenosis. Fifty-six patients with rheumatic mitral stenosis were studied using imaging and Doppler echocardiography. Aliasing velocities of 20 to 23 cm/s were used to record the flow vonvergence region proximal to the stenotic mitral orifice. The stroke volume (mL) was calculated by multiplying peak transmitral flow rate which was obtained using an angle-corrected hemispheric flow convergence equation, by transmitral velocity time integral (cm) divided by peak transmitral velocity (cm/s) recorded using continuous wave Doppler method. Stroke volume calculated using the flow convergence region method was not significantly different from that calculated using aortic Doppler two-dimensional echocardiographic method in 39 patients with pure mitral stenosis (75+/-19 [mean+/-1SD] versus 73+/-19 mL, P=0.12), and from that calculated using pulmonic Doppler two-dimensional echocardiographic method in nine patients with mitral stenosis with associated>2+ aortic regurgitation (77+/-12 versus 75+/-14 mL, P=0.49). No significant difference existed between the cardiac output obtained using the flow convergence region method and that obtained using Fick method in 12 patients with pure mitral stenosis. The stroke volume was overestimated by the flow convergence region method when compared with those obtained using aortic Doppler two-dimensional echocardiographic method in patients with mitral stenosis with associated >2+ mitral regurgitation (123+/-40 versus 67+/-15 mL, P=0.001). The present study provided an alternative way to calculate the stroke volume and cardiac output in patients with mitral stenosis.

  2. Cost-effectiveness of a cardiac output-guided haemodynamic therapy algorithm in high-risk patients undergoing major gastrointestinal surgery.

    PubMed

    Sadique, Zia; Harrison, David A; Grieve, Richard; Rowan, Kathryn M; Pearse, Rupert M

    2015-01-01

    The use of cardiac output monitoring to guide intra-venous fluid and inotropic therapies may improve peri-operative outcomes, but uncertainty exists regarding clinical effectiveness and robust cost-effectiveness evidence is lacking. The objective of the study was to evaluate the cost-effectiveness of peri-operative cardiac output-guided haemodynamic therapy versus usual care in high-risk patients undergoing major gastrointestinal surgery. The study undertook a cost-effectiveness analysis using data from a multi-centre randomised trial that recruited patients from 17 hospitals in the United Kingdom. The trial compared cardiac output-guided, haemodynamic therapy algorithm for intra-venous fluid and inotrope (dopexamine) infusion during and 6 h following surgery, with usual care. Resource use and outcome data on 734 high-risk trial patients aged over 50 years undergoing major gastrointestinal surgery were used to report cost-effectiveness at 6 months and to project lifetime cost-effectiveness. The cost-effectiveness analysis used information on health-related quality of life (QoL) at randomisation, 30 days, and 6 months combined with information on vital status to report quality-adjusted life years (QALYs). Each QALY was valued using the National Institute for Health and Care Excellence (NICE) recommended threshold of willingness to pay (£20,000 per QALY) in conjunction with the costs of each group to report the incremental net monetary benefits (INB) of the treatment algorithm versus usual care. The mean [SD] quality of life at 30 days and 6 months was similar between the treatment groups (at 6 months, intervention group 0.73 [0.28] versus usual care group 0.71 [0.30]; mean gain 0.03 [95 % confidence interval (CI) -0.01 to 0.08]). At 6 months, survival, mean QALYs and mean healthcare costs (intervention group £8574 versus usual care group £8974) were also similar. At the cost-effectiveness threshold of £20,000 per QALY gained, the incremental net

  3. Mouse anaphylactic shock is caused by reduced cardiac output, but not by systemic vasodilatation or pulmonary vasoconstriction, via PAF and histamine.

    PubMed

    Wang, Mofei; Shibamoto, Toshishige; Tanida, Mamoru; Kuda, Yuhichi; Kurata, Yasutaka

    2014-10-29

    Systemic anaphylaxis is life-threatening, and its pathophysiology is not fully clarified. Mice are frequently used for experimental study on anaphylaxis. However, the hemodynamic features and mechanisms of mouse anaphylactic hypotension remain unknown. Therefore, we determined mechanisms of systemic and pulmonary vascular response to anaphylactic hypotension in anesthetized BALB/c mice by using receptor antagonists of chemical mediators. Anaphylaxis was actively induced by an intravenous injection of the ovalbumin antigen into open-chest artificially ventilated sensitized mice. Mean arterial pressure (MAP), pulmonary arterial pressure (PAP), left atrial pressure, central venous pressure, and aortic blood flow (ABF) were continuously measured. In sensitized control mice, MAP and ABF showed initial, transient increases, followed by progressive decreases after the antigen injection. Total peripheral resistance (TPR) did not decrease, while PAP initially and transiently increased to 18.5±0.5mmHg and pulmonary vascular resistance (PVR) also significantly increased. The antigen-induced decreases in MAP and ABF were attenuated by pretreatment with either a platelet-activating factor (PAF) receptor antagonist, CV6209, or a histamine H1 receptor antagonist, diphenhydramine, and were abolished by their combination. Diphenhydramine augmented the initial increases in PAP and PVR, but did not affect the decrease of the corresponding MAP fall. The antagonists of either leukotriene C4 or serotonin, alone or in combination with CV6209, exerted no significant effects. Mouse anaphylactic hypotension is caused by a decrease in cardiac output but not vasodilatation, via actions of PAF and histamine. The slight increase in PAP is not involved in mouse anaphylactic hypotension. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. The year of transparency: measuring quality of cardiac care.

    PubMed

    Eindhoven, D C; Wierda, E; de Bruijne, M C; Amoroso, G; de Mol, B A J M; Umans, V A W M; Schalij, M J; Borleffs, C J W

    2015-09-01

    The assessment of quality of care is becoming increasingly important in healthcare, both globally and in the Netherlands. The Dutch Minister of Health declared 2015 to be the year of transparency, thereby aiming to improve quality of care by transparent reporting of outcome data. With the increasing importance of transparency, knowledge on quality measurement will be essential for a cardiologist in daily clinical care. To that end, this paper provides a comprehensive overview of the Dutch healthcare structure, quality indicators and the current and future assessment of quality of cardiac care in the Netherlands.

  5. Automated Data Abstraction of Cardiopulmonary Resuscitation Process Measures for Complete Episodes of Cardiac Arrest Resuscitation.

    PubMed

    Lin, Steve; Turgulov, Anuar; Taher, Ahmed; Buick, Jason E; Byers, Adam; Drennan, Ian R; Hu, Samantha; J Morrison, Laurie

    2016-10-01

    Cardiopulmonary resuscitation (CPR) process measures research and quality assurance has traditionally been limited to the first 5 minutes of resuscitation due to significant costs in time, resources, and personnel from manual data abstraction. CPR performance may change over time during prolonged resuscitations, which represents a significant knowledge gap. Moreover, currently available commercial software output of CPR process measures are difficult to analyze. The objective was to develop and validate a software program to help automate the abstraction and transfer of CPR process measures data from electronic defibrillators for complete episodes of cardiac arrest resuscitation. We developed a software program to facilitate and help automate CPR data abstraction and transfer from electronic defibrillators for entire resuscitation episodes. Using an intermediary Extensible Markup Language export file, the automated software transfers CPR process measures data (electrocardiogram [ECG] number, CPR start time, number of ventilations, number of chest compressions, compression rate per minute, compression depth per minute, compression fraction, and end-tidal CO2 per minute). We performed an internal validation of the software program on 50 randomly selected cardiac arrest cases with resuscitation durations between 15 and 60 minutes. CPR process measures were manually abstracted and transferred independently by two trained data abstractors and by the automated software program, followed by manual interpretation of raw ECG tracings, treatment interventions, and patient events. Error rates and the time needed for data abstraction, transfer, and interpretation were measured for both manual and automated methods, compared to an additional independent reviewer. A total of 9,826 data points were each abstracted by the two abstractors and by the software program. Manual data abstraction resulted in a total of six errors (0.06%) compared to zero errors by the software program

  6. Measurement of Voltage Level Output by Magnetic Tunneling Junction by Rectification of RF Signals

    DTIC Science & Technology

    2011-04-13

    MTJ ) was measured. This was accomplished using both a broadband log periodic antenna and broadband ridge horn antenna as a radio frequency (RF) source...Transmission frequencies ranged from 1 to 6 GHz at varied power levels of 0 to 20 dBm. The signal was received by a coplanar waveguide antenna. A MTJ ...Slavin Steven Zielinski 4/13/2011 Abstract In this experiment, the DC voltage output of a magnetic tunneling junction ( MTJ ) was measured. This

  7. The detector characteristics for output factor measurement of small field electron beams

    NASA Astrophysics Data System (ADS)

    Wulandari, C.; Wibowo, W. E.; Pawiro, S. A.

    2017-07-01

    Have been performed the output factor measurements of the small square field with dimensions of 8 x 8 cm2 and smaller, for electron beams with energy of 6, 8, 10, 12, and 15 MeV. The experiments has been performed using the Elekta Synergy Platform Linac, solid water, the Exradin A11 plan-parallel ion chamber, Exradin A16 micro ion chamber, PTW Freiburg T60010M-4 silicon diode, and Gafchromic® EBT-3 film. The result described that the output factor of all detectors decreased with decreasing field size and energy electron beams. The comparison of output factor to output at reference condition for all detectors has discrepancy maximum in the range of 49.5-87.6 % on field 1 x 1 cm2 for 6 MeV, and a minimum value in the range of of 0.49-1.21 % on 8 x 8 cm2 for 15 MeV so it makes the dose distribution of electron treatment of square field of 1 x 1 cm2 were not appropriate for patient treatment. In this study, PTW Freiburg T60010M-4 silicon diode and Gafchromic® EBT-3 film demonstrated more compatible for small field electron beam measurement.

  8. Can early cardiac troponin I measurement help to predict recent coronary occlusion in out-of-hospital cardiac arrest survivors?

    PubMed

    Dumas, Florence; Manzo-Silberman, Stephane; Fichet, Jérôme; Mami, Zohair; Zuber, Benjamin; Vivien, Benoît; Chenevier-Gobeaux, Camille; Varenne, Olivier; Empana, Jean-Philippe; Pène, Frédéric; Spaulding, Christian; Cariou, Alain

    2012-06-01

    Recent guidelines recommend the immediate performance of a coronary angiography when an acute myocardial infarction is suspected as a cause of out-of-hospital cardiac arrest. However, prehospital factors such as postresuscitation electrocardiogram pattern or clinical features are poorly sensitive in this setting. We searched to evaluate if an early measurement of cardiac troponin I can help to detect a recent coronary occlusion in out-of-hospital cardiac arrest. Retrospective analysis of a prospective electronic registry database. University cardiac arrest center. Between January 2003 and December 2008, 422 out-of-hospital cardiac arrest survivors without obvious extra-cardiac cause have been consecutively studied. An immediate coronary angiography has been systematically performed. The primary outcome was the finding of a recent coronary occlusion. First, blood cardiac troponin I levels at admission were analyzed to assess the optimum cutoff for identifying a recent coronary occlusion. Second, a logistic regression was performed to determine early predictive factors of a recent coronary occlusion (including cardiac troponin I) and their respective contribution. An ST-segment elevation was present in 127 of 422 patients (30%). During coronary angiography, a recent occlusion has been detected in 193 of 422 patients (46%). The optimum cardiac troponin I threshold was determined at 4.66 ng·mL(-1) (sensitivity 66.7%, specificity 66.4%). In multivariate analyses, in addition of smoking and epinephrine initial dose, cardiac troponin I (odds ratio 3.58 [2.03-6.32], p < .001) and ST-segment elevation (odds ratio 10.19 [5.39-19.26], p < .001) were independent predictive factors of a recent coronary occlusion. In this large cohort of out-of-hospital cardiac arrest patients, isolated early cardiac troponin I measurement is modestly predictive of a recent coronary occlusion. Furthermore, the contribution of this parameter even in association with other factors does not seem