Cardiac Output By Thermodilution Technique: Effect of Injectate’s Volume and Temperature on Accuracy and Reproducibility in the Critically III Patient

doi:10.1378/chest.84.4.418

Chest

Volume 84, Issue 4, October 1983, Pages 418-422

https://doi.org/10.1378/chest.84.4.418 Get rights and content

We compared determinations of cardiac output using various combinations of injectate volumes and temperatures to results obtained with 10 ml of iced (0°C) injectate (standard technique) in 33 critically ill patients. The use of a 10-ml injectate at room temperature resulted in comparable reproducibility (12.7 vs 10.8 percent; not significant) and a small and nonsignificant error (–0.013 ± 0.543 L/min). Five milliliters at room temperature resulted in markedly decreased reproducibility (17.9 vs 8.9 percent; p<0.05); however, the error associated with the technique was still not significant (0.136 ± 0.829 L/min). When a 5-ml injectate at 0°C was used, a reproducibility comparable to that of 10 ml at 0°C was obtained (12.3 vs 7.5 percent; not significant). The results underestimated values obtained with 10 ml at 0°C (–0.360 ± 0.857 L/minute); however, the difference did not reach statistical significance. The use of 3 ml at 0°C was associated with a substantial increase in variability, with a coefficient of variation of 32.0 percent (10.4 percent for 10 ml of iced injectate; p<0.01); however, the differences between the average value of cardiac output obtained with this technique and the standard technique were only minimal (error, –0.063 ± 0.455; not significant). We reached the following conclusions: (1) the use of 10 ml at room temperature and 5 ml at 0°C as the indicator for thermodilution determinations of cardiac output results in small and insignificant differences in reproducibility and accuracy from the standard technique; (2) five milliliters at room temperature and 3 ml at 0°C are associated with markedly decreased reproducibility; however, the error in values for cardiac output obtained with these techniques is not statistically significant; and (3) the ability to use injectate at room temperature and in small volume should substantially simplify the technique, lowering its cost, and should prevent volume overloading.

Section snippets

Population of Patients

A validation of our thermodilution technique against dye dilution was performed in 15 men and 12 women between the ages of 26 and 66 years. All patients had undergone diagnostic cardiac catheterization for cardiac symptoms at the University of California Irvine Medical Center. Twenty-two patients had coronary arterial disease, and two patients had rheumatic mitral valvular disease. One patient had a combination of coronary arterial disease and mitral valvular prolapse, one patient had an aortic

RESULTS

Table 1 presents the reproducibility of the dye dilution and thermodilution techniques for measuring cardiac output. Shown in the table are the mean values for cardiac output, intrapatient SD, and coefficient of variation for each technique and the number of determinations. Using the first two, first three, and all five determinations of cardiac output by the thermodilution technique produced results which were not less reproducible than that using two measurements by the dye dilution method

DISCUSSION

Although the thermodilution technique for the measurement of cardiac output has been widely used, there are few data available dealing with its accuracy and reproducibility in the clinical setting. In the setting of the cardiac catheterization laboratory, where the study was performed in hemodynamically stable, mildly sedated patients, our results confirm previous reports²^,³ demonstrating close agreement between thermodilution and dye dilution for measurement of cardiac output. The

ACKNOWLEDGMENT

We are greatly indebted to the nurses of the Cardiac Care Unit and the Catheterization Laboratory of the University of California Irvine Medical Center for their invaluable help in this study. We also thank Michael Mumford, M.D., and Johnathan Tobis, M. D., for their support and Mrs. Dione Fosdick for her excellent secretarial assistance.

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Hemodynamic monitoring is the repeated assessment of circulatory function over time. Perturbations in circulatory function are expected during physiologic stress such as surgery. Uncontrolled, these perturbations can lead to tissue hypoxia, ultimately resulting in perioperative morbidity and mortality. As such, hemodynamic monitoring is a fundamental component of delivering safe anesthetic care. It is essential to note, however, that hemodynamic monitoring alone does not change anesthetic or surgical outcomes. To improve perioperative outcomes, hemodynamic monitoring must not only be of high quality, but the measurements must also be interpreted correctly, so that the anesthesiologist can intervene in an appropriate and timely fashion. Poor quality measurements or a misinterpretation of hemodynamic monitors will lead to incorrect therapeutic decisions resulting in adverse outcomes.
Accuracy of noninvasive estimated continuous cardiac output (esCCO) compared to thermodilution cardiac output: A pilot study in cardiac patients
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Citation Excerpt :
First, it is an imperfect standard with well-documented intrinsic errors of 15-20%. This intrinsic error can be attributed partially to respiratory variations and hemodynamic changes in patients, yet these variations in the real world patient cannot account for all of the intrinsic error.5,13–15 Second, the PAC remains an invasive monitor with very real potential complications, most commonly transient arrhythmias and rarely pulmonary artery rupture.6
To compare the noninvasive estimated continuous cardiac output (esCCO), device-derived cardiac output (CO) to simultaneous pulmonary artery catheter (PAC) thermodilution (TD) CO.
A prospective study comparing pulse wave transit time (estimated continuous cardiac output, esCCO; Nihon Kohden, Tokyo, Japan) to intermittent TD CO.
One academic hospital.
Patients presenting for cardiac surgery.
Intraoperative CO measurements at 4 distinct time points (after induction, after sternotomy, after cardiopulmonary bypass, and after chest closure).
The study population consisted of American Society of Anesthesiologists (ASA) IV subjects, 27 (77%) males and 8 (23%) females, with a mean age of 64.6±12.2 years. Data points from esCCO and TD were collected simultaneously and means per time point compared using Bland-Altman, Pearson R coefficient, and percent error. Mean TD CO for the study was 5.4 L/min. The Pearson R coefficient, percent error, and bias in L/min were: 0.57, 44%, 0.66 (after induction); 0.54, 51%, 0.88 (after sternotomy); 0.60, 60%, 0.95 (after cardiopulmonary bypass); and 0.57, 60%, 0.75 (after chest closure) respectively.
esCCO is easy to use and provides continuous CO measurements, but has wide limits of agreement and large percentage errors with a consistently positive bias in comparison to TD.
Lack of agreement between pulmonary arterial thermodilution cardiac output and the pressure recording analytical method in postoperative cardiac surgery patients
2011, British Journal of Anaesthesia
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The average of three 1 min continuous registrations with 1 min intervals between each was taken as the representative result. The sample size was adjusted to comparable comparison studies.11 20 No formal power analysis was performed.
Pulse-contour analysis method (PCM) cardiac output (CO) monitors are increasingly used for CO monitoring during anaesthesia and in the critically ill. Very recently, several systems have been introduced that do not need calibration; among them the pressure recording analytical method (PRAM). Sparse data comparing the accuracy of the PRAM-CO with conventional thermodilution CO (ThD-CO) in cardiac surgery patients are available.
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A total of 46 paired CO measurements (23 for each interval) were collected. The Bland–Altman analysis showed a mean difference (bias) of 0.0 litre min⁻¹ and limits of agreement (1.96 sd) of 4.53 to −4.54 litre min⁻¹ [upper 95% confidence interval (CI), 3.26–5.80; lower 95% CI, −5.8 to −3.27]. The percentage error (1.96 sd/mean of the reference method) was 87%.
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Knowledge of the enhancement pattern on each patient enables CT scanning with elaborate protocols for these purposes. However, prospective studies of the relationship between cardiac output and the aortic enhancement pattern of CT scans may be difficult, because the thermodilution technique, which is the most typical method of cardiac output measurement using the catheterization procedure, is needed [11,12]. Furthermore, it may be also difficult to select a patient group with varying cardiac output.
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: Manuscript received March 7; revision accepted May 31.

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Cardiac Output By Thermodilution Technique: Effect of Injectate’s Volume and Temperature on Accuracy and Reproducibility in the Critically III Patient

Section snippets

Population of Patients

RESULTS

DISCUSSION

ACKNOWLEDGMENT

Am J Cardiol

Am J Cardiol

Am J Cardiol

Measurement of cardiac output in anesthetized animals by a thermo-dilution method

Q J Exp Physiol

Measurement of cardiac output by thermodilution

N Engl J Med

Statistical principles in experimental design.