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PubMedDate not supplied

Thermodilution cardiac output determinations: a comparison of iced and refrigerated injectate temperatures in patients after cardiac surgery.

OBJECTIVE: To compare cardiac output determinations with two temperatures of injectate: iced (0 degrees to 6 degrees C) and refrigerated (10 degrees to 16 degrees C) in adult patients after cardiac surgery. DESIGN: A quasi-experimental study design was used. The dependent variable was cardiac output. The independent variable was injectate temperature. Each patient served as his or her own control. SETTING: Intensive care unit at a 500-bed urban teaching hospital in Western Canada. SAMPLE: A convenience sample of 40 male and female patients admitted to the intensive care unit after myocardial revascularization and/or valvular surgery between March and August 1991. All patients experienced surgery with the normothermic technique. METHOD: Each subject had cardiac output determinations performed within 12 hours of surgery with both 10 ml refrigerated and 10 ml iced injectate. The capped syringe technique was used. DATA ANALYSIS: A paired t test was performed to determine statistically significant differences between the two sets of measurements. Regression analysis was used to determine strength of agreement between the two techniques. Clinical significance was examined by a difference in mean cardiac output greater than 15% resulting in an alteration in medical therapy. RESULTS: There were no statistically or clinically significant differences between the two methods of cardiac output determinations. Regression analysis showed very good agreement (r = 0.965, p < 0.0001). Clinically, when the two cardiac outputs were reported to the surgeon, medical therapy was not altered based on differences. CONCLUSIONS: The use of 10 ml of refrigerated injectate provides reproducible cardiac output results as compared with iced injectate in normothermic patients after cardiac surgery. Further investigation is required to generalize these results to other patient populations and to determine the reproducibility with a lower volume of injectate.

Adult↗
PubMedDate not supplied

Issues in methods and measurement of thermodilution cardiac output.

Criterion-related validity of the thermodilution cardiac output technique for cardiac output measurement has to have a high correlation (r = .91 to .98) with the direct Fick method, the gold standard of cardiac output measurement. Issues that can affect validity of the measurements include the position of the pulmonary artery catheter, the rate of injection of the indicator solution, the volume and temperature of the injectate, the timing of the injection of indicator solution during the respiratory cycle, the position of the subject, and the presence of concomitant infusions. Variation in measurement can be limited by considering the delivery system for the indicator solution, by recording time-temperature cardiac output curves, and by considering normal biologic variations.

Cardiac Output↗
PubMed1987

Effects of alpha-adrenoceptor agonists on cardiac output and its regional distribution in the pithed rat.

Cardiac output, its distribution and tissue blood flows were determined with tracer microspheres in pithed rats during pressor responses elicited by either alpha 1-adrenoceptor agonists (cirazoline, phenylephrine) or alpha 2-adrenoceptor agonists (xylaxine, B-HT 933). Two doses were used for each of cirazoline and B-HT 933 and phenylephrine was investigated in the presence of propranolol (3 mg kg-1). The rats were pithed under halothane anaesthesia. Cardiac output was increased by xylazine, the higher dose of B-HT 933 and phenylephrine. Heart rate was increased by phenylephrine and the higher doses of both cirazoline and B-HT 933. Stroke volume was greater in those groups given xylazine, phenylephrine and the higher dose of B-HT 933 but was decreased in those animals given the higher dose of cirazoline. Both alpha 2-adrenoceptor agonists increased the number of microspheres trapped in the lungs and the proportion of the cardiac output passing through the hepatic artery but decreased that flowing through the spleen and gastrointestinal tract. The higher dose of B-HT 933 also decreased the fraction of cardiac output flowing to the kidneys but kidney blood flow was maintained as a result of the increased cardiac output. Also, this treatment reduced blood flow in the epididimal fat pads. Both alpha 1-adrenoceptor agonists increased the fraction of cardiac output received by the coronary vasculature but the only other effect on distribution common to these agents was an increase in the percentage of the cardiac output passing to the hepatic artery. Cirazoline decreased the proportion of cardiac output distributed to the gastrointestinal tract and spleen but the total fraction of cardiac output passing to the hepatosplanchnic region was maintained as a result of the increase to the hepatic artery. Cirazoline markedly reduced the proportion of the cardiac output received by the kidneys and absolute flow in these organs was only 1.4% of control after the higher dose of this agonist but flow at the lower dose was maintained by the higher cardiac output. It is concluded that there is a significant contribution to the pressor responses elicited by alpha-agonists resulting from an alpha-adrenoceptor-mediated increase in cardiac output that may result from greater heart rates or stroke volumes. Also, there is a differential distribution of alpha-receptor subtypes throughout the vasculature which is especially noticeable in the kidneys.

Adrenergic alpha-Agonists↗
PubMed1998

A bolus dose of 1.5 mg/kg amrinone effectively improves low cardiac output state following separation from cardiopulmonary bypass in cardiac surgical patients.

BACKGROUND: The aim of this study was to evaluate the efficacy of 1.5 mg/kg bolus of amrinone on low cardiac output (CO) state following emergence from cardiopulmonary bypass (CPB) in cardiac surgical patients. METHODS: Immediately after emergency from CPB, 14 patients with a cardiac index (CI) less than 2.2 l.min-1.m-2 despite administration of inotropes and nitroglycerin, received 1.5 mg/kg amrinone over 3 min without changing catecholamine infusion rates (amrinone group). Hemodynamics and left ventricular short axis views with transesophageal echocardiography were recorded at baseline, 3, 4, and 10 min following amrinone administration. Left ventricular filling volumes were maintained constant by volume reinfusion from the CPB reservoir. We matched the data of the amrinone group with the other 14 patients who did not receive amrinone (non-amrinone group) to evaluate the efficacy of amrinone in low CO state. RESULTS: At baseline, CI (1.8 +/- 0.1 l.min-1.m-2) in the amrinone group was significantly lower than CI (3.0 +/- 0.2) in the non-amrinone group. Following amrinone administration, CI and velocity of circumferential fibershortening corrected for heart rate (Vcfc) significantly increased, and systemic vascular resistance index and pulmonary vascular resistance index significantly decreased from the baseline within 10 min without changes in heart rate, mean arterial blood pressure, or pulmonary artery occlusion pressure, and became equivalent with those of the non-amrinone group. CONCLUSIONS: A 1.5 mg/kg amrinone loading dose to patients in a low CO state, despite catecholamine therapy immediately after emergence from CPB, effectively improves ventricular function when loading conditions are maintained constant.

Adult↗
PubMed1997

Evaluation of the accuracy and response time of STAT-mode continuous cardiac output.

OBJECTIVES: This study was conducted to compare continuous cardiac output (CCO) with bolus thermodilution cardiac output (BTD) at steady state, and to compare the response time of STAT CCO with that of trend CCO, mean arterial pressure, and mixed venous oxygen saturation [SvO2] during an acute hemodynamic change. DESIGN: Prospective study. SETTING: University hospital. PARTICIPANTS: Twenty-nine patients undergoing cardiac surgery or liver transplantation. INTERVENTIONS: STAT and trend CCO were compared with BTD cardiac output during steady state intraoperatively and postoperatively in the intensive care unit. Ten patients, who required epicardial pacing after cardiac surgery, were studied to compare the response time of STAT CCO with that of trend CCO, mean arterial pressure, and BvO2 after a 10% to 20% increase in pacing rate. MEASUREMENTS AND MAIN RESULTS: A total of 108 cardiac output data sets were analyzed at steady state. Steady state was defined as stable heart rate and mean arterial pressure (+/- 5%) and stable central venous pressure (+/- 2 mmHg) measured immediately before and after each data set. Cardiac output ranged from 2.3 to 8.5 L/min. The correlation between STAT CCO and BTD was r = 0.94, and for trend CCO and BTD was r = 0.94. The bies and precision for STAT CCO versus BTD were 0.06 L/min (Cl 95%: -0.08 to 0.18) and 0.61 L/min. The bias and precision for trend CCO versus BTD were 0.06 L/min (Cl 95%: -0.04 to 0.16) and 0.49 L/min. Eleven data sets were analyzed to study response time of STAT CCO, which was defined as the first time the percent change of the mean of each variable was significantly increased from baseline. Significant increases in mean arterial pressure and SvO2 were detected after 30 seconds (2.5%, p = 0.01) and 90 seconds (2.0%, p = 0.04), respectively. A significant increase in STAT CCO was reached at 270 seconds (4.4%, p = 0.005). Trend CCO tended to increase but did not reach statistical significance within 6 minutes. CONCLUSIONS: STAT and trend CCO are accurate and precise and show close agreement with BTD cardiac output at steady state. The faster algorithm of STAT CCO offers some advantage over trend CCO during an acute hemodynamic change. However, because of the averaging process for determining CCO, the response time of STAT CCO is slower than that of mean arterial pressure and SvO2.

Algorithms↗
PubMed2002

Finapres arterial pulse wave analysis with Modelflow is not a reliable non-invasive method for assessment of cardiac output.

Non-invasive continuous monitoring of cardiac output could be very useful in clinical care and in research settings, particularly in elderly subjects. We studied whether Finapres arterial pulse wave analysis with Modelflow is a reliable non-invasive method for the assessment of cardiac output in healthy elderly subjects. We compared Modelflow cardiac output (MFCO) with thermodilution cardiac output (TDCO) in 28 healthy subjects, aged 70+/-4 years (mean+/-S.D.). TDCO was measured during right-sided heart catheterization, while MFCO was calculated with Modelflow(R) software from non-invasive arterial Finapres blood pressure, which was measured simultaneously. The two methods were compared using a paired t-test, by Pearson correlation, and by Bland-Altman analysis. TDCO was 6.4+/-1.1 litres/min (mean+/-S.D.) and MFCO was 4.7+/-1.3 litres/min (P<0.001). There was no significant correlation between MFCO and TDCO (r=0.28, P=0.13). Mean difference (bias) was -1.7 litres/min (S.E.M. 0.27 litres/min), with an S.D. (precision) of 1.5 litres/min. The 95% limits of agreement were -4.6 to +1.1 litres/min. In conclusion, non-invasive MFCO values differed significantly from and showed no significant correlation with invasively determined TDCO values in the normal range. Although simple, non-invasive and patient-friendly, the Modelflow method is inaccurate for assessment of cardiac output without invasive calibration.

Aged↗
PubMed1984

Norepinephrine plus phentolamine improves regional blood flow during experimental low cardiac output syndrome.

A complication of cardiac surgical procedures is postoperative low cardiac output syndrome. Treatment with norepinephrine plus phentolamine (N + P) is beneficial, but the effect of these agents on regional organ blood flow has not been evaluated. Therefore, in 6 dogs with long-term instrumentation, pentobarbital was infused to simulate low cardiac output (32 + 10% of the conscious control level). Infusions of N + P at 0.2, 0.5, and 1.0 microgram/kg/min restored cardiac pump performance to conscious control levels. Regional blood flows, determined with tracer-labeled microspheres, were substantially reduced in the low cardiac output state but increased to values not markedly different from control levels in all organs studied except stomach fundus during infusion of N + P. The pressure-work index, an indirect measure of myocardial oxygen consumption, did not increase to more than the conscious level except at the highest dose. The data demonstrate that simultaneous infusion of N and P is capable of successfully improving cardiac pump performance with restoration of vital organ perfusion and without evidence of excessive myocardial oxygen consumption.

Animals↗
PubMed2000

[Optimal dose of indocyanine-green injected from the peripheral vein in cardiac output measurement by pulse dye-densitometry].

Cardiac output is measured by pulse dye-densitometry using indocyanine-green (ICG). This cardiac output is estimated by correlating with the cardiac output measured by pulmonary artery catheter using thermodilution method. Twenty-four patients scheduled for elective cardiovascular surgeries under general anesthesia were studied. The pulse dye-densitometry monitoring system used was DDG-2001 (Nihon Kohden, Japan). In group A (13 patients: 19 times), ICG was administered from the peripheral vein as bolus doses of 5, 10 or 20 mg (5 mg.ml-1 water solution). In group B (11 patients: 12 times), ICG was administered from the peripheral vein as bolus doses of 20, 10 or 5 mg (5 mg.ml-1 water solution). The correlation (Pearson's correlation coefficient) and precision (the method proposed by Bland and Altman) compared with cardiac output measured by pulmonary artery catheter were examined. Better correlation and precision were recognized after 20 mg ICG injection than 5 or 10 mg ICG injection. In conclusion, the measurement of cardiac output by pulse dye-densitometry with peripheral vein ICG injection was useful using a bolus dose of ICG 20 mg.

Aged↗
PubMedDate not supplied

[Pharmacological correction of low cardiac output syndrome in hemofiltration].

Low cardiac output was corrected by catecholamines in the course of hemofiltration (HF) administered to 37 patients with multiple organ failure after surgery. Catecholamines (adrenaline hydrochloride, noradrenaline hydrotartrate, dopamine hydrochloride, and dobutamine hydrochloride) were used as monotherapy or in various combinations (two, three, or four drugs). Ninety percent of patients with low cardiac output subjected to HF were administered combined catecholamine therapy. Catecholamines provided the hemodynamic stability of HF in patients with low cardiac output. The frequency of noradrenaline administrations and its mean doses were reliably decreased in the course of HF, whereas the mean doses of adrenaline, dopamine, and dobutamine remained virtually the same.

Cardiac Output, Low↗
PubMed1991

Intraoperative estimation of cardiac output by transesophageal pulsed Doppler echocardiography.

To determine whether transesophageal echocardiography could be used to estimate intraoperative cardiac output, the authors studied 35 consecutive patients undergoing cardiovascular surgery (coronary artery disease [n = 22], aortic valve disease [n = 5], mitral valve stenosis [n = 5], peripheral vascular disease [n = 3]). Two-dimensional echocardiographic and pulsed-wave Doppler signals of the pulmonary artery and mitral valve flow velocity were obtained simultaneously with thermodilution measurements of cardiac output. Cardiac output derived from pulsed Doppler imaging of pulmonary artery systolic flow velocity modestly correlated with the thermodilution-derived cardiac output (r = 0.65), but output determined from the mitral valve diastolic flow velocity did not (r = 0.24). Transesophageal echocardiography of pulmonary artery systolic flow satisfactorily detected intraoperative increases in cardiac output greater than 15% (sensitivity, 71%; specificity, 82%) but not decreases (sensitivity, 54%; specificity, 90%). Although this technique identifies increases in cardiac output greater than 15%, it does not detect decreases as accurately as those detected by thermodilution measurements. At this time, therefore, transesophageal Doppler echocardiography has significant limitations as an off-line monitor of cardiac output.

Adult↗
PubMed1996

[A comparison of various ways of cardiac output measurement by thermodilution methods].

We compared cardiac output values obtained by the following 3 methods: 1. Iced bolus injectate method, using the injectate temperature actually measured for computation [bolus cardiac output with flow-through temperature probe: BCO (p)]. 2. Continuous cardiac output measurement, using Vigilance system (continuous cardiac output: CCO). 3. Iced bolus injectate method, assuming injectate temperature to be 0 degrees C (bolus cardiac output without flow-through temperature probe: BCO). Only the subject receiving cardiovascular surgeries using cardiopulmonary bypass (CPB), and requiring a thermodilution catheter for hemodynamic monitoring during anesthesia were selected for the study. The total cases consisted of 15 patients (10 males), in which 60 measurement were made. Following the anesthetic induction with fentanyl, midazolam, vecuronium bromide, and intubation, a Baxter Swan-Ganz CCO thermodilution catheter was inserted through the right internal jugular vein. Compared to BCO(p), CCO showed excellent precision and bias; (r2 = 0.935, P < 0.0001, bias = -0.19 l.min-1, SD = 0.36 l.min-1). Although BCO correlated well with BCO(p), the bias was much greater (r2 = 0.919, P < 0.0001, bias = -1.25 l.min-1, SD = 0.45 l.min-1) than BCO(p). In conclusion, the values obtained by BCO(p) and CCO methods were very accurate. On the other hand, a considerable overestimation was found with BCO since the compensation for actual injectate temperature was not performed

Cardiac Output↗
PubMed1993

The value of Doppler echocardiography in cardiac output detection.

In the present study simultaneous measurements of cardiac output by thermodilution method and Doppler echocardiography were obtained 105 times in five persons with congestive cardiomyopathy. A significant degree of correlation (r = 0.79) was verified between the values of cardiac output measured by the two methods. To estimate the accuracy of echocardiography for consecutive measurements of cardiac output, all of the patients were given a positive inotropic drug: 5 mg milrinone per os. After that the cardiac output was measured, first by thermodilution and immediately after that by the Doppler method, in successive time periods: 15 minutes after the drug, then 30, 45, 60 and 90 minutes later, and then 2, 3, 4 and 5 hours after the drug. The same procedure was repeated with all subjects after application of 10 mg milrinone per os. By statistical analysis of differences between the cardiac output measured by both methods, a low connection was found (r = 0.43). In addition, when the increase of cardiac output was registered, the Doppler method showed a decrease of cardiac output, both methods had similar directional changes, but the numeric data was not correct. This performed study demonstrated that the measurement of cardiac output by thermodilution and continuous Doppler echocardiography had good correlation. However, Doppler echocardiography cannot replace classic invasive methods in consecutive measurements and monitoring of cardiac output in seriously ill cardiac patients.

Cardiac Output↗