ISSUES IN METHODS AND MEASUREMENT OF THERMODILUTION CARDIAC-OUTPUT

Criterion-related validity of the thermodilution cardiac output techni que 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 measuremen ts 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 t he respiratory cycle, the position of the subject, and the presence of concomitant infusions. Variation in measurement can be limited by con sidering the delivery system for the indicator solution, by recording time-temperature cardiac output curves, and by considering normal biol ogic variations.