In determining cardaic outputs, there are Fick´s method, dye dilution method and thermodilution method. Among these, he thermodilution method is widely used because it is simple; relatively accurate and easily duplicated. Nowadays this method has been recognized as a valuable means for the patient´s status monitoring in intensive care unit and operating room.
The use of 10 ml, 05C saline or 5 % D/W has been recommended as the standard indicator. Indicator may be modified to use room temperature or small volume.
Therefore this study was carried out to investigate the effect of indicator volume, temperature and catheter tip position on cardiac output determinations.
Using artificial cardiopulmonary system, cardiac output measurements by thermodilution method wereperformed at different indicator temperature (1 C, 19.5C, 24.5C), different indicator volume (3 ml, 5 ml, 10 ml), various catheter tip positions in pulmonary artery (apex, initial center, peripheral center, base).
The results were as follows:
1. The use of smaller indicator volume resulted in increase of mean cardiac output compared to the control and decrease in reproducibility.
2. The use of higher indicator temperature markedly decreased the reproducibility.
3. When the catheter tip was positioned in the central initial pulmonary artery, the cardiac output
values were similar to the control but all values of other position. were also acceptable for clinical
use.
4. To reduce the errors it was preferable to use low temperature indicator when smaller indicator volume is used.
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