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.


METHODS
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.


METHODS
Intensive care unit at a 500-bed urban teaching hospital in Western Canada.


METHODS
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.


METHODS
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.


METHODS
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.
ACCN Program, Foothills Hospital School of Nursing, Calgary, Alberta, Canada.
P
P
Price
B
B
Fowlow
D000328:Adult; D000368:Aged; D002302:Cardiac Output; D006348:Cardiac Surgical Procedures; D001026:Coronary Artery Bypass; D005260:Female; D006334:Heart Function Tests / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D012044:Regression Analysis; D015203:Reproducibility of Results; D013696:Temperature; D013815:Thermodilution