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Thermodilution right ventricular ejection fraction measurements: room temperature versus cold temperature injectate
1Surgical Critical Care Service, Vanderbilt University, Nashville, TN 37232-2100.
Insights
Room temperature injectate can be used for right ventricular ejection fraction measurements in critically ill surgical patients. This method offers potential time and cost savings in the intensive care unit.
Area of Science:
- Critical Care Medicine
- Cardiovascular Physiology
- Medical Device Technology
Background:
- Thermodilution is a common method for measuring right ventricular ejection fraction (RVEF).
- The temperature of the injectate (room vs. cold) may influence measurement accuracy.
- Standard protocols often recommend cold injectate, potentially increasing procedure time and cost.
Purpose of the Study:
- To compare the accuracy and reproducibility of RVEF measurements using room temperature versus cold temperature injectate.
- To determine if room temperature injectate is a viable alternative for RVEF assessment in adult surgical intensive care unit (ICU) patients.
Main Methods:
- A prospective clinical study was conducted in an adult surgical ICU.
- Sixty patients requiring pulmonary artery catheterization underwent RVEF measurements.
- Room temperature (23.9°C) and cold (8.0°C) 10 mL injectate thermodilution measurements were alternated and compared.
Main Results:
- No significant difference was found between RVEF measurements using room temperature versus cold temperature injectate (p = .752).
- A high degree of correlation was observed between the two methods (r² = .876, p < .001).
- Bias was -0.39% with a precision of +/- 3.3%, and reproducibility was comparable between groups.
Conclusions:
- Room temperature injectate is a reliable alternative for RVEF measurements in critically ill adult surgical patients.
- Using room temperature injectate can potentially reduce procedure time and healthcare costs in the ICU.
- This finding supports simplifying thermodilution protocols without compromising measurement quality.
Objective:
To compare thermodilution right ventricular ejection fraction measurements using 10 mL room temperature injectate vs. 10 mL cold temperature injectate.
Design:
Prospective, clinical study.
Setting:
Adult surgical intensive care unit (ICU) in a university hospital.
Patients:
Sixty adult surgical ICU patients requiring hemodynamic monitoring by a pulmonary artery catheter.
Interventions:
Patients were in a supine position with the bed flat during thermodilution measurements. Four 10 mL room temperature injections were alternated with four 10 mL cold temperature injections.
Measurements And Main Results:
One hundred eleven paired thermodilution right ventricular ejection fraction measurements were made in patients during a "steady state." There were no restrictions regarding body temperature, cardiac index, heart rate or rhythm. Injectate temperature was measured by an in-line temperature probe. Injections were synchronized with end-expiration of mechanical ventilator breaths. The first injection was deleted from each temperature group. Reproducibility of individual right ventricular ejection fraction measurements was assessed by calculating the mean variation of triplicate measurements in each temperature group. Mean values of room temperature measurements were compared with cold temperature measurements by Student's t-test. Linear regression analysis, bias, and precision were also calculated. There was no significant difference (p = .752) between mean right ventricular ejection fraction measurements determined with room temperature (23.9 +/- 1 degrees C) vs. cold temperature (8.0 +/- 1.1 degrees C) injectate. There was a high degree of correlation between measurements (r2 = .876, p < .001). The bias of room temperature measurements compared with cold temperature was -0.39% and the precision was +/- 3.3%. The mean variation between individual measurements in all room temperature and cold temperature right ventricular ejection fraction measurements was 9.7% and 8.0%, respectively. There was no significant difference and there was a high degree of correlation in mean right ventricular ejection fraction measurements when data were grouped according to body temperature, heart rate, cardiac index, right ventricular ejection fraction, central venous pressure, pulmonary vascular resistance index, right ventricular end-diastolic volume index, or right ventricular stroke work index.
Conclusions:
The results suggest that room temperature injectate may be used for right ventricular ejection fraction measurements in critically ill adult surgical patients. Utilizing room temperature injectate for right ventricular ejection fraction measurements may save time and costs in the critical care unit.
