Transesophageal Doppler scanning versus thermodilution during general anesthesia. An initial comparison of cardiac output techniques.

Measurement of cardiac output has become an essential feature of anesthetic management of patients with cardiac disease requiring operation. Thermodilution by way of a Swan-Ganz catheter is the current popular technique for cardiac output determination. Unfortunately, this method is costly and has an associated irreducible morbidity rate and has, in rare instances, resulted in death. The suprasternal ultrasonographic Doppler technique has shown promise for measuring cardiac output noninvasively; however, it is too cumbersome for continuous intraoperative use. In an effort to overcome this limitation, the esophageal stethoscope was modified to accept a Doppler probe. Herein, we have reported an initial comparison of transesophageal Doppler scanning and thermodilution in 23 adult men during general anesthesia. The average difference between thermodilution and descending cardiac output was 0.16 +/- 0.81 liters/min. The correlation between thermodilution and descending cardiac output increased with operator experience. In the last 13 patients, there was an average correlation of 0.85. After the equipment was mastered and improvements in design were made, descending cardiac output had a high correlation with thermodilution and appeared to track the dynamic changes during general anesthesia.