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PubMed2005

Comparison of thermal dilution and electrical impedance dilution methods for measurement of cardiac output in standing and exercising horses.

OBJECTIVE: To compare cardiac output measured in the pulmonary artery and a carotid artery by use of thermal and electrical impedance dilution. Animals-7 fit, clinically normal Standardbreds between 2 and 5 years of age. PROCEDURE: Transient changes in electrical impedance and temperature of blood were induced by bolus injections of ice-cold saline hypertonic (6% and 9% NaCl) solutions. Cardiac output was calculated by applying Stewart-Hamilton principles to the indicator dilution transients. Measurements were made during sequential exercise episodes on a level treadmill over approximately an 8-fold range of cardiac output values. RESULTS: We detected agreement between cardiac output determined by use of electrical impedance dilution at the pulmonary artery and carotid artery. Cardiac output from thermal dilution measured at the carotid artery exceeded that measured at the pulmonary artery. Cardiac output from the thermal dilution technique exceeded cardiac output from the electrical impedance dilution technique at both locations. CONCLUSIONS AND CLINICAL RELEVANCE: The electrical impedance indicator is conserved on first transit; therefore cardiac output measured by electrical impedance dilution at the carotid artery is reliable over a large range of values. Thermal dilution provides a larger estimate of cardiac output, compared with the electrical impedance dilution technique, probably because of a loss of indicator. The transpulmonary electrical impedance dilution technique may have potential for clinical application, particularly in animals in which catheterization of the pulmonary artery is not appropriate or blood loss must be minimized.

Animals↗
PubMed1996

Comparison of transesophageal echocardiographic, fick, and thermodilution cardiac output in critically ill patients.

PURPOSE: Recent observations have highlighted errors in the thermodilution technique of measuring cardiac output. Thus, cardiac output measurements using transesophageal echocardiography and the Fick method were compared with simultaneous thermodilution measurements. METHODS: In 13 mechanically ventilated critically ill patients, cardiac output was determined simultaneously using (1) transesophageal echocardiography (COTEE, (2) the Fick method (COFICK, and (3) thermodilution (COTD immediately before and after a rapid infusion of 500 mL of saline. Left ventricular end-diastolic and end-systolic areas were measured using the transesophageal echocardiographic transgastric short axis view, and COTEE was calculated from the corresponding volumes. Absolute cardiac output values and the changes from before to after saline infusion (delta CO) were compared using analysis of variance, linear regression, and the Bland and Altman method. RESULTS: There were no significant differences between COTEE (8.0 +/- 3.4), COFICK (8.4 +/- 3.3), and COTD (8.3 +/- 3.0) or between delta COTEE, delta COFICK, and delta COTD using analysis of variance. However, correlations between COTEE and COTD (r2 = 0.46; P < .00001), COFICK and COTD (r2 = 0.46; P < .0001), and COTEE and COFICK (r2 = 0.42; P < .0001) were only moderately good. Using the method of Bland and Altman, the mean difference (+/-2 standard deviations) between COTEE and COTD was 0.3 +/- 4.3 L/min, between COFICK and COTD was -1.0 +/- 3.8 L/min, and between COTEE and COFICK was 0.6 +/- 5.6 L/min, whereas the difference between delta COTEE and delta COTD was 0% +/- 26%, between delta COFICK and delta COTD was 9% +/- 46%, and between delta COTEE and delta COFICK was 8% +/- 39%. CONCLUSIONS: There are substantial differences in cardiac output as measured by these three methods, best demonstrated using the method of Bland and Altman. The variability of cardiac output and its derivatives (eg, oxygen delivery) should be borne in mind when making clinical decisions on individual patients.

Analysis of Variance↗
PubMed2006

Cardiac output--pulse contour analysis vs. pulmonary artery thermodilution.

BACKGROUND: The aims of this study were to determine the agreement between pulmonary artery thermodilution (PA-TD), transpulmonary thermodilution (TP-TD) and the pulse contour method, and to test the ability of the pulse contour method to track changes in cardiac output. METHODS: Cardiac output was determined twice before cardiac surgery with both PA-TD and TP-TD. The precision (two standard deviations of the difference between repeated measurements) and agreement of the two methods were calculated. Post-operatively, cardiac output was determined with the PA-TD and pulse contour methods, and the bias and limits of agreement were again calculated. Finally, in patients with heart rates below 60 beats/min or a cardiac index of less than 2.5 l/min/m2, atrial pacing was started and the haemodynamic consequences were monitored with the PA-TD and pulse contour methods. RESULTS: Twenty-five patients were included. The precisions of PA-TD and TP-TD were 0.41 l/min [95% confidence interval (CI), +/- 0.07] and 0.48 l/min (95% CI, +/- 0.08), respectively. The bias and limits of agreement between PA-TD and TP-TD were - 0.46 l/min (95% CI, +/- 0.11) and +/- 1.10 l/min (95% CI, +/- 0.19), respectively. Post-operatively, the bias and limits of agreement between the PA-TD and pulse contour methods were 0.07 l/min and +/- 2.20 l/min, respectively. The changes in cardiac output with atrial pacing were in the same direction and of the same magnitude in 15 of the 16 patients. CONCLUSION: The precision of cardiac output measurements with PA-TD and TP-TD was very similar. The transpulmonary method, however, overestimated the cardiac output by 0.46 l/min. Post-operatively, cardiac output measurements with the PA-TD and pulse contour methods did not agree, but the pulse contour method reliably tracked pacing-induced changes in cardiac output.

Adult↗
PubMed1977

Effect of high-altitude exposure for 10 days on stroke volume and cardiac output.

Resting stroke volume and cardiac output of 50 normal healthy sea-level residents (group A) were estimated by the noninvasive technique of electrical impedance plethysmography. They were then airlifted to an altitude of 3,658 m and serial estimations carried out at 0-4 h and 5-8 h and on the 2nd, 3rd, 4th, 5th, and 10th days. The subjects were brought back to sea level and studied for up to 5 days. Thirty permanent residents of high altitude (group B) and sixteen lowlanders temporarily resident at high altitude (group C) were also subjected to similar studies. It was found that resting stroke volume and cardiac output of group A started falling immediately on arrival at high altitude, reached the minimum on the 3rd day and tended to improved on the 4th and 5th day, but showed a secondary fall on the 10th day. The reduction in stroke volume in this group was not fully compensated by tachycardia. On return to sea level the cardiac output normalized immediately, the stroke volume on the 2nd day. At sea level goup A had values similar to group B and at high altitude to group C.

Adult↗
PubMed1995

High-output cardiac failure due to excessive shunting in a hemodialysis access fistula: an easily overlooked diagnosis.

A dialysis arteriovenous fistula caused life-threatening high-output cardiac failure in a 66-year-old patient. Excessive shunting through the dialysis fistula was demonstrated by invasive measurement of cardiac output, systemic arterial blood pressure, systemic vascular resistance, and oxygen consumption before and after temporary occlusion of the dialysis fistula. Noninvasive echocardiographic evaluation of the influence of fistula compression on cardiac output and noninvasive duplex measurement of the fistula flow also confirmed the diagnosis. Following surgical closure of the fistula, the patient's condition improved, and signs of congestive heart failure subsided. High-output cardiac failure is a rare complication of dialysis arteriovenous fistulas. The diagnosis may remain unrecognized for longer periods. Noninvasive methods for estimation of the hemodynamic importance of a fistula may be of help in the establishment of the proper diagnosis.

Aged↗
PubMed1994

Is continuous cardiac output measurement using thermodilution reliable in the critically ill patient?

OBJECTIVE: Evaluation of continuous cardiac output monitoring based on the thermodilution technique in the critically ill. DESIGN: Prospective clinical investigation. SETTING: A surgical intensive care unit of a university hospital. PATIENTS: Thirty-five critically ill patients (trauma and/or sepsis patients), who needed pulmonary artery catheterization. The patients were prospectively studied according to the following groups: a) patients with a heart rate of > 120 beats/min; b) those patients with a cardiac output of > 10 L/min; c) patients with a cardiac output of < 4.5 L/min; d) patients with a rectal temperature of > 39.0 degrees C; and e) patients with a pulmonary artery catheter inserted for > 4 days. INTERVENTIONS: Therapies were carried out according to modern intensive care medicine protocols by physicians who were not involved in the study. MEASUREMENTS: Cardiac output was monitored continuously using a new, modified pulmonary artery catheter. This catheter has a heating filament by which energy is transmitted to the circulating blood (modified thermodilution technique). A bedside microprocessor calculated cardiac output using a new algorithm. Standard bolus thermodilution technique (10 mL of ice-cold saline solution) was used to compare the continuous cardiac output measurement with the intermittent bolus cardiac output measurement. MAIN RESULTS: A total of 404 pairs of intermittent (bolus) cardiac output and continuous cardiac output measurements were obtained from the 35 patients. The bias (mean difference between bolus cardiac output measurement and continuous cardiac output measurement) of all measurements was 0.03 +/- 0.52 L/min and the 95% confidence limit (mean difference +/- 2 SD) was -1.01/1.06 L/min. Also, continuous cardiac output measurement agreed closely with bolus cardiac output measurement (bias was 0.16 +/- 0.57 L/min in the cardiac output of > 10 L/min group; bias was -0.17 +/- 0.50 L/min for the cardiac output of < 4.5 L/min group). Increased temperature and prolonged length of stay did not influence the agreement of continuous cardiac output measurement with bolus cardiac output measurement (bias was 0.09 +/- 0.51 L/min in the > 39 degrees C rectal temperature group). CONCLUSIONS: Continuous monitoring of cardiac output using a modified pulmonary artery catheter with a heated filament has proven to be accurate and precise in the critically ill patient when compared with the "standard" intermittent bolus thermodilution technique. The continuous monitoring technique enhances our armamentarium for more intensive monitoring of these patients under a variety of circumstances.

Adult↗
PubMed1995

Thermodilution cardiac output may be incorrect in patients on venovenous extracorporeal lung assist.

Cardiac output measurement is part of routine monitoring in critically ill patients. In patients on extracorporeal lung assist, thermodilution cardiac output measurement may lead to erroneous results caused by indicator loss into the extracorporeal circuit. Seven patients on venovenous extracorporeal lung assist were studied using different extracorporeal blood flows. We compared conventional thermodilution cardiac output determinations with dye dilution cardiac output measurement, with dye injection into the pulmonary artery. The latter method is not affected by the extracorporeal circuit. The conventional thermodilution method overestimated cardiac output up to a maximum of 300%, providing results up to 10 L/min higher than true cardiac output. The mean difference between thermodilution and true cardiac output as determined by dye dilution with pulmonary artery indicator injection was 3.0 +/- 2.41 L/min. There was no correlation between thermodilution cardiac output values and true cardiac output (r = 0.06). We conclude that conventional thermodilution is not a suitable method for cardiac output measurement in patients on extracorporeal lung assist, especially if high extracorporeal blood flows are applied.

Adult↗
PubMed1991

Cardiac output from carbon dioxide production and arterial and venous oximetry.

OBJECTIVE: To determine cardiac output from measurements of CO2 production (VCO2), and arterial (SaO2) and mixed venous (SvO2) oxygen saturations, using a modified Fick equation, in which cardiac output = VCO2/[k (SaO2 - SvO2)], where k represents a constant. DESIGN: A metabolic measurement cart was used to measure VCO2 and oxygen consumption (VO2) at 3-min intervals. SaO2 and SvO2 were measured via a pulse oximeter and a fiberoptic right heart catheter, respectively. The initial value of k for each study was determined from initial simultaneous measurements of thermodilution cardiac output, VCO2, SaO2, and SvO2 via the equation k = VCO2/[cardiac output (SaO2 - SvO2)]. The value of k was assumed to remain constant for the entire study period. Thereafter, cardiac outputs calculated from k and the measurements of VCO2, SaO2, and SvO2 were compared with the simultaneously obtained cardiac outputs determined by thermodilution. Similarly, cardiac outputs calculated from the traditional oxygen Fick equation, where cardiac output = VO2/[13.4 x hemoglobin (SaO2 - SvO2)], were compared with the simultaneously acquired cardiac outputs determined by thermodilution. SETTING: Surgical ICU in a Veterans Affairs Medical Center. PATIENTS: Seven postoperative patients, mechanically ventilated using the intermittent mandatory ventilation mode, were studied over a mean period of 4 hrs. RESULTS: Cardiac output (obtained from VCO2 and oximetry saturations) was closely related to thermodilution cardiac output: with linear regression showing r2 = .96 and standard error of the estimate = 0.59 L/min, n = 21; and, with bias and precision = 0.17 and 0.68 L/min, respectively. The traditional oxygen Fick cardiac output was also closely related to the thermodilution cardiac output (r2 = .81, standard error of the estimate = 1.46 L/min, n = 22; bias and precision = 0.31 and 1.46 L/min, respectively). CONCLUSION: The proposed method for calculating cardiac outputs solely from VCO2 and oximetry saturations yields results that correspond closely to thermodilution determined cardiac outputs. The method is simple and avoids the difficulties in the Fick method associated with accurate VO2 measurement. This approach may be suitable for continuous cardiac output monitoring in critically ill patients.

Aged↗
PubMed1995

[Continuous measurement of cardiac output with pulse contour analysis].

Pulse contour cardiac output (PCCO) is an easily applicable method for continuous measurement of cardiac output in critically ill patients. Calculation of stroke volume is possible by analysing the area under the systolic part of the arterial pulse pressure waveform together with an individual calibration factor (Zao) to account for the individually variable vascular impedance. Since vascular impedance is potentially affected by altered vascular tone, it was the aim of the present study to examine the validity of PCCO in ICU patients receiving various dosages of a variety of vasoactive drugs. PATIENTS AND METHODS. Continuous cardiac output was measured in 20 ICU patients for a total of 110 h using the pulse contour method. The precision of PCCO was determined in comparison with its calibration reference, the thermodilution method (TDCO): (1) during administration of vasoactive drugs at a constant rate and (2) during conditions with altered vascular tone and haemodynamics elicited by changes in vasoactive drug dosage. For this purpose, the patients received varying dosages of vasoactive drugs (dopamine, dobutamine, epinephrine, norepinephrine, nitroglycerin, prostacyclin and urapidil). RESULTS. A total of 165 data sets was obtained, each consisting of the average of four capnometrically triggered TDCO measurements and the corresponding PCCO values. The relative difference between methods (+/- 2 SD) was +/- 23.9% (SD 0.85 l.min-1; r = 0.93) if a single calibration at the beginning of measurement series was performed (Fig. 2). The bias of the mean cardiac output values of both methods was -0.09 l.min-1. The precision of PCCO improved to +/- 15.7% by additional calibrations (SD 0.56.min-1; r = 0.96; bias 0.003 l.min-1). Data of two patients showed that recalibration may be necessary after extreme haemodynamic changes due to septic shock or cooling. Alteration of vascular tone by clinically used dosage of vasoactive drugs, however, had no destabilizing effect on the pulse contour method. CONCLUSIONS. It could be demonstrated that PCCO provides a valuable method for continuous cardiac output measurement in the intensive care setting with a precision comparable to that of thermodilution.

Adult↗
PubMedDate not supplied

Backrest angle and cardiac output measurement in critically ill patients.

BACKGROUND: Cardiac output is an extremely important measurement in the care of critically ill patients, but the accuracy of measurement is unknown when patients are in positions other than flat and supine. OBJECTIVE: The purpose of this study was to compare the effects of varying degrees of backrest elevation on continuous cardiac output measurements in critically ill patients at head-of-bed angle of 0 degrees, 30 degrees, and 45 degrees, and at time points of 0 minutes, 5 minutes, and 10 minutes after each position change. METHOD: A within participants design using a convenience sample (N = 26). Data were collected in a 24-bed adult Medical/Surgical/Trauma Intensive Care Unit. A continuous cardiac output catheter was used for all continuous cardiac measurements and continuous cardiac output values were indexed to continuous cardiac index values. RESULTS: Four repeated measures analyses of variance (ANOVA) were run, one for each dependent variable (continuous cardiac index, stroke volume, heart rate, and mean arterial pressure). There were two within participant factors with three levels each (time and head-of-bed angle). The results indicated no overall significant differences in continuous cardiac index values at the various head-of-bed angle and time points (p =.715). In addition, no significant differences were found for stroke volume (p =.614), heart rate (p =.289) or mean arterial pressure (p =.246). CONCLUSION: No differences in the continuous cardiac index values across the nine different measurement conditions were found. An examination of the determinants of cardiac output (stroke volume and heart rate) indicated that the lack of change in continuous cardiac index was not a result of a compensatory change in either stroke volume or heart rate. These data indicate that in daily clinical practice with critical medical surgical patients it may be unnecessary to reposition patients solely for the purpose of obtaining continuous cardiac index measurements. The measurements appear to be reproducible at head-of-bed angle up to 45 degrees.

Adaptation, Physiological↗
PubMed1992

Transoesophageal Doppler echocardiographic measurement of cardiac output by the mitral annulus method.

OBJECTIVE: To compare cardiac output measured by the transoesophageal Doppler and thermodilution techniques. DESIGN: Prospective direct comparison of paired measurements by both techniques in each patient. SETTING: Intensive care unit in a cardiovascular centre. PATIENTS: 65 patients after open heart surgery (mean (SD) age 53 (12) years). INTERVENTIONS: Cardiac output was measured simultaneously by the transoesophageal Doppler and thermodilution techniques. Cardiac output was measured again after a mechanical intervention or volume loading. RESULTS: The limits of agreement were -2.53 to +0.83 1.min-1 for cardiac output measured by the Doppler and thermodilution techniques. This suggests that the Doppler method alone would not be suitable for clinical use. The second measurement of cardiac output by thermodilution was compared with cardiac output estimated from the first and second Doppler measurements and the first thermodilution measurement. The limits of agreement (-0.55 to +0.51 1.min-1) were good enough for clinical use. CONCLUSIONS: After cardiac output had been measured simultaneously by both the Doppler and thermodilution techniques, subsequent transoesophageal Doppler alone gave a clinically useful measurement of cardiac output.

Adult↗
PubMed1996

Negative-pressure ventilation improves cardiac output after right heart surgery.

BACKGROUND: A low cardiac output state can complicate the postoperative course of patients undergoing Fontan-type operations and tetralogy of Fallot repair. METHODS AND RESULTS: We investigated the effect of negative-pressure ventilation on cardiac output in 11 children in the early postoperative period after right heart surgery. All patients were initially ventilated with volume-cycled intermittent positive-pressure ventilation, and negative-pressure ventilation was delivered with the Hayek external high-frequency oscillator. Cardiac output was calculated by the direct Fick method, oxygen consumption being measured by respiratory mass spectrometry. Cardiac output was measured during intermittent positive-pressure ventilation and after 15 minutes of negative-pressure ventilation. Negative-pressure ventilation improved the cardiac output by a mean of 46% (P = .005). Heart rate did not change, and stroke volume increased by a mean of 48.5% (P = .005). Mixed venous saturation increased by 4.6% (P < .02), and consequently arteriovenous oxygen content difference fell significantly (P = .01). The systemic and pulmonary vascular resistances were reduced significantly during negative-pressure ventilation (P < .05 and P < .03, respectively). CONCLUSIONS: Negative-pressure ventilation improves cardiac output in children after total cavopulmonary connection and tetralogy of Fallot repair and may prove to be an important therapeutic option in children with the low cardiac output state.

Adolescent↗
PubMed1983

Effect of dietary restriction, during the last week only or throughout gestation, on cardiac output and uteroplacental blood flow in pregnant rats.

Cardiac output and uteroplacental blood flow were measured by using 15-microns radioactive labeled microspheres in ad libitum-fed nonpregnant female rats, and in pregnant rats: 1) fed ad libitum; 2) fed a 50% restricted diet from day 14 of gestation on; and 3) fed a 50% restricted diet from day 5 of gestation on. Dietary restriction induced fetal growth retardation regardless of duration. Cardiac output in both groups of diet-restricted dams was 30% less than that of the ad libitum-fed pregnant dams, and not significantly increased above that of the nonpregnant rats. Total uterine and placental blood flows in the dams fed the restricted diet during the last week of gestation were reduced 30-35% relative to the ad libitum-fed dams due to the reduced cardiac output. In the dams fed the restricted diet from day 5, total uterine and placental blood flows were reduced 60-65% due to both the reduced cardiac output and a decreased fractional distribution of cardiac output to the uterus. Dietary treatment had no effect on blood flow to the kidneys and ovaries. The results suggest that the reduced placental blood flow associated with maternal malnutrition-induced fetal growth retardation is caused by an inadequate expansion of maternal cardiac output, and, if malnutrition is severe enough, a fractional redistribution of cardiac output away from the uterus and developing conceptus occurs.

Animals↗
PubMed1998

Thermodilution measurement of cardiac output in patients with low output: room-temperature versus iced injectate.

BACKGROUND: Measurements of cardiac output with the thermodilution technique add to data for clinical decision making and therefore must be valid and reliable. However, the results of studies on the accuracy of values obtained with room-temperature and iced injectates, especially in patients with high or low cardiac output, have been conflicting. OBJECTIVE: To determine the effect of the temperature of the injectate (iced or room temperature) on cardiac output values obtained with the thermodilution technique in critically ill adults with known low cardiac output. METHODS: A convenience sample of 50 subjects (41 men and 9 women) who had a cardiac index of less than 2.5 (calculated as cardiac output in liters per minute divided by body surface area in square meters) before the study had cardiac output measured by using a closed system and manual injections of room-temperature and iced injectates. RESULTS: A paired t test indicated no significant difference between iced and room-temperature injectates for cardiac output (iced, 3.62 L/min; room temperature, 3.71 L/min; t = 0.99; P = .327) and cardiac index (iced, 1.95; room temperature, 1.99; t = 0.71; P = .482). CONCLUSION: The findings support the practice of using room-temperature injectate to measure cardiac output in patients with low cardiac output.

Adult↗
PubMedDate not supplied

Effect of continuous positive airway pressure on cardiac output in neonates.

To determine the cardiac output change in neonates who were under nasal continuous positive airway pressure (CPAP) therapy, eleven newborn neonates, who were admitted to our neonatal intensive care unit with respiratory diseases, were enrolled in the study. Cardiac output was measured by pulsed Doppler echocardiogram at various pressures of 0, 2, 4, 6, 8, and 10 cm H2O and revealed 301 +/- 47, 300 +/- 49, 289 +/- 55, 275 +/- 64, 269 +/- 59 and 242 +/- 50 ml/min/kg, respectively. Cardiac output depressed significantly between 0 cm H2O and 8 cm H2O (P = 0.025), and between 0 cm H2O and 10 cm H2O (P = 0.004). We conclude that cardiac output may be depressed in neonates who are under high levels of nasal CPAP therapy, and suggest that high levels of nasal CPAP therapy must be used with caution, especially when the therapy is applied to the low birth weight neonates.

Cardiac Output↗
PubMed1990

Frequently repeated Fick cardiac output measurements during anesthesia.

A computer-based system was developed for monitoring cardiac output using the Fick principle during general anesthesia. The variables of the oxygen-consumption Fick equation were measured using the following system: oxygen uptake by an originally developed respiratory gas monitoring system, arteriovenous oxygen saturation difference by pulse and fiberoptic oximetry, and hemoglobin concentration by an in vitro oximeter. Fick cardiac output and systemic vascular resistance were calculated every 30 seconds. Fick cardiac output was compared with thermodilution cardiac output in 11 anesthetized patients. A total of 208 corresponding cardiac output measurements showed a range of 2 to 9 L.min-1. The correlation coefficient between the thermodilution and Fick cardiac outputs was 0.961, with a regression equation of Fick cardiac output = 1.058 thermodilution cardiac output - 0.359. The difference between the thermodilution and Fick cardiac outputs was 0.103 +/- 0.395. The Fick cardiac output was significantly lower than the thermodilution cardiac output, especially in the low flow range. We demonstrated that this new monitoring system was clinically feasible and sufficiently accurate, under the limited circumstances of our study. The integration of routinely used equipment has made possible a frequently repeatable method for estimating cardiac output in patients.

Anesthesia, General↗
PubMedDate not supplied

Comparative overview of cardiac output measurement methods: has impedance cardiography come of age?

Cardiac output, usually expressed as liters of blood ejected by the left ventricle per minute, is a fundamental measure of the adequacy of myocardial function to meet the perfusion needs of tissue at any time. Decreases in cardiac output over time (when cardiac output is measured under similar conditions) may signal myocardial functional deterioration and the onset or progression of heart failure. Conversely, improvements in cardiac output may indicate a positive response to medical therapy. However, most methods for evaluating cardiac output are technically demanding, require specialized training and specialized environments for measurement, and are costly. Therefore, most measurement techniques are impractical for routine evaluation of disease progression and/or response to treatment in the prevention and/or management of heart failure. This paper provides a comparative overview of commonly employed cardiac output measurement strategies with emphasis on developments in impedance cardiography which suggest that impedance cardiography has the potential to make routine assessment and trending of cardiac output a viable alternative to assist in the management of both chronically and acutely ill patients, including those with heart failure. (c)2000 by CHF, Inc.

Journal Article↗
PubMed1984

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

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.

Animals↗