Thermodilution Cardiac Output Determinations Research Articles

Comparative Radionuclide and Thermodilution Determinations of Cardiac Output and Stroke Volume in the Baboon (Papio ursinus)

Thermodilution cardiac output determinations and multigated equilibrium blood-pool scintigraphy were performed in ten healthy chacma baboons (Papio ursinus). The correlation was moderately good between both the radionuclide and thermodilution stroke volume (r = 0.58, SEE = 3 ml; SVth = 0.78SVr + 15.6 ml) as well as the cardiac output (r = 0.72, SEE = 0.2 liter/min; COth = 0.56 Cor + 2.1 liter/min). The attenuation depth dr as determined by radionuclide techniques was found to correlate well with the radiologically determined values dx (r = 0.8, SEE = 0.4 cm; dx = 0.87dr + 0.72 cm) which validated the depth values used in the calculations.

Allometric determination of the distance from the central venous pressure port to wedge position of balloon-tip catheters in pediatric patients.

Position of the CVP port on a flow-directed balloon-tip pulmonary arterial catheter affects the accuracy of both thermodilution cardiac output determinations and CVP measurements. Systemic allometry (the study of the growth of a part in relation to the total organism) has been used to determine an easily measured independent variable that would predict this position. Sixty-one pediatric patients (aged 0 to 165 months) were studied either at autopsy or at the time of cardiac catheterization. The distance from the central venous port to the wedge position was best predicted by nonlinear manipulation of age.

Effect of injectate volume and temperature on thermodilution cardiac output determination.

Six combinations of injectate volume (10, 5, and 3 ml) and temperature (0 degree C and room temperature [RT]) are recommended by the manufacturers of thermodilution cardiac output catheters and computers. We prospectively studied the accuracy and variability associated with these six combinations in critically ill patients requiring intermittent mandatory ventilation. The six methods were similar in their average estimation of cardiac output but differed markedly in their reproducibility. The 10 ml 0 degree C and 10 ml RT combinations produced the least variability. The 5 ml 0 degree C and 5 ml RT combinations produced more variability. Variability was much greater with the remaining two combinations. The 3 ml RT combination resulted in an average range of 1.71 1/min within each set of three repeat measurements and an average absolute difference of 1.51 1/min from the values obtained with 10 ml 0 degree C (each the mean of three injections). We recommend the use of 10 ml 0 degree C or 10 ml RT for cardiac output determinations in critically ill patients. If it is important to minimize volume administration, the use of 5 ml injectate is acceptable for an estimation of cardiac output. The use of 3 ml injectate volumes is rarely, if ever, justified because the small reduction in volume administration results in a large increase in variability.

The slowing of sinus rhythm during thermodilution cardiac output determination and the effect of altering injectate temperature.

The slowing of sinus rhythm during thermodilution cardiac output determination and the effect of altering injectate temperature.

Ventricular Fibrillation during Thermodilution Cardiac Output Determination

Ventricular Fibrillation during Thermodilution Cardiac Output Determination

Patient selection for iced versus room temperature injectate for thermodilution cardiac output determinations

In 42 patients who required hemodynamic monitoring there was no statistically significant difference between mean cardiac output determined with iced vs. room temperature injectate. There was also no statistical difference in mean cardiac output values using iced vs. room temperature injectate when data were grouped according to body temperature, mean arterial pressure, and cardiac output. These results suggest that when cardiac output is measured by the methods described, the use of iced injectate is unnecessary in many critically ill patients.

Thermodilution cardiac output studies as a cause of prosthetic valve bacterial endocarditis

The injectate used for thermodilution cardiac output determinations is a potential source for direct bloodstream contamination, resulting in bacterial endocarditis after cardiac operations. An experiment simulating three techniques for obtaining injectate samples showed one of them to be clearly unacceptable.

Limitations of thermodilution cardiac output measurements in the rat.

Heat loss from the vascular system could introduce an error in thermodilution cardiac output determinations. Cardiac output measured in the rat via the thermodilution technique following right atrial injection yielded different values (P less than 0.001), depending whether sampling was from the pulmonary artery (460 +/- 31 ml X min-1 X kg-1), right ventricle (311 +/- 19), or thoracic aorta (245 +/- 15). Recirculation errors could not account for the differences. Heat loss from the vascular system was measured from extravascular thermistors within both the thorax and the abdomen. These dilutions were 22-57% in peak height of aortic curves recorded at approximately the same location. Differences in calculated cardiac output between sampling sites could be attributed to rapid heat conduction directly from the right atrium and inferior vena cava to the thoracic aorta with progressive loss of indicator from both the right ventricle and pulmonary artery.

Continuous S-vO2 measurement and oxygen transport patterns in cardiac surgery patients.

Twenty adult cardiac surgery patients with impaired ventricular function by contrast ventriculography at cardiac catheterization were monitored from before anesthesia until the time of extubation up to 12 h postoperatively. A thermodilution pulmonary artery catheter with fiberoptic channels for continuous measurement of mixed-venous oxygen saturation (S-vO2) by reflection oximetry was substituted for the usual catheter. The S-vO2 was recorded continuously along with blood pressure, cardiac filling pressures, and heart rate. Thermodilution cardiac output determinations were used to derive hemodynamic and oxygen transport indices. There was a consistently high and significant negative correlation (r = -.84) between S-vO2 and the percentage of oxygen extracted from blood. Thus, S-vO2 reflects oxygen extraction and continuous S-vO2 provides continuous quantification of global oxygen extraction. None of the other oxygen transport variables including cardiac index showed significant correlation with S-vO2. The oximetry system provides a continuous and reliable indication of mixed-venous blood oxygenation which is a continuous reflection of oxygen extraction.

The Hemodynamic Tracking System

In the operating room or intensive care unit, multiple measurements of circulatory function are almost mandatory in patients with significant cardiovascular disease. Use in these areas requires that the information must be easily organized, rapidly obtained, and inexpensive. A hemodynamic tracking system that meets these criteria is described. This system incorporates a hand-held programmable calculator (cost = $210 to $300) to derive variables computed from standard cardiovascular measurements. The time required to obtain a set of measurements (including thermodilution cardiac output determinations in duplicate), key the numbers into the calculator, and obtain the derived indices is 4 minutes. Two patients, who had acute mitral insufficiency and whose clinical management differed substantially are presented to illustrate the use of data obtained from the hemodynamic tracking system.

PEEP and CPAP Following Open-heart Surgery in Infants and Children

The cardiorespiratory effects of 5 cm H2O end-expiratory pressure were studied in 22 infants and children an hour after open-heart surgery during mechanical ventilation with positive end-expiratory pressure (PEEP) and prior to endotracheal extubation approximately 15 hours later during spontaneous breathing (CPAP). Thermodilution cardiac output determinations and respiratory airflow, volume and pressure recordings were made to assess the effects of airway pressure changes on the respiratory waveform and oxygen delivery. Neither PEEP nor CPAP had a significant effect on cardiac output, intrapulmonary shunting, oxygen consumption, or oxygen utilization. Patients who had had pulmonary hypertension preoperatively did not behave differently from those without pulmonary hypertension when removed from ventilatory supprot. Expiratory airflow was significantly prolonged when positive end-expiratory pressure existed during both controlled and spontaneous respiration. During CPAP, this "expiratory braking" was associated with an increase in tidal volume and decreases in respiratory rate and minute volume. Because of the lack of improvement in cardiopulmonary function in this group of patients, and the possibility of untoward effects from sustained end-expiratory pressure, PEEP and CPAP might properly be reserved as temporary supportive techniques should respiratory function be compromised.

Pulmonary artery catheterization and thermodilution cardiac output determination in the management of critically burned patients

Pulmonary artery catheterization and thermodilution cardiac output determination in the management of critically burned patients

Pulmonary artery catheterization and thermodilution cardiac output determination in the management of critically burned patients

Pulmonary artery catheterization was performed in thirty-nine critically burned patients. Hemodynamic changes, induced by thermal injury and its therapy, were measured. Pulmonary wedge pressure was found to be a more reliable indicator of circulating volume, whereas central venous pressure was often misleading. Measurements of both pulmonary hemodynamics and cardiac output were necessary to manage patients requiring high levels of pulmonary end-expiratory pressure (PEEP). These measurements enable one to define optimum PEEP levels which provide maximum oxygen delivery to the tissues. Depressed myocardial function was seen in the early phase of the injury. In this period dopamine administration increased left ventricular stroke work index with minimal changes in filling pressures. The usefulness of dopamine in treating this early myocardial depression deserves further study. Catheter-related complications were minimal when the catheters were used for periods of three days or less.

Validity of thermodilution cardiac output determination: Experimental studies with and without pulmonary insufficiency

Validity of thermodilution cardiac output determination: Experimental studies with and without pulmonary insufficiency

Assessment of thermodilution cardiac output in small subjects

Thermodilution cardiac output determinations were compared with dye-dilution measurements in normovolemic and hypovolemic puppies. Good correlation was achieved with small volumes of cold and warm saline. Injectate volumes and significant caval displacement of the injectate port did not significantly affect thermodilution output measurements. This study demonstrates that thermodilution is a reliable and practical method of cardiac output determination in small subjects and suggests that this technique may be useful in the clinical mangement of neonates and small infants.

Error in thermodilution cardiac output measurement caused by variation in syringe volume.

It is important to measure the exact volume of 5% dextrose injected when thermodilution cardiac output determinations are made. The marked volume on plastic syringes and their variability may contribute to a small but significant error in the results.

Thermodilution cardiac output determination with a single flow-directed catheter

Thermodilution cardiac output determination with a single flow-directed catheter

Thermodilution cardiac output determination with a single flow-directed catheter

A single right heart catheter which allows simultaneous determinations of cardiac output, pulmonary artery pressure, pulmonary capillary wedge pressure, and right atrial pressure in critically ill patients is described. The catheter, which utilizes the thermodilution technique of cardiac output determination, may be rapidly and safely passed at the bedside without fluoroscopy.

Effects of E. coli endotoxemia on ventricular performance.

Effects of E. coli endotoxemia on ventricular performance.

On the theory of the indicator-dilution method for measurement of blood flow and volume.

On the theory of the indicator-dilution method for measurement of blood flow and volume.