Noninvasive monitoring of cardiac output in critically ill patients: transesophageal Doppler vs transesophageal echocardiography

Introduction

Transesophageal Doppler (TED) increases prognosis in perioperative time [1] by detecting cardiac output (CO) variations [2]. Transesophageal echocardiography (TEE) is progressively considered as an alternative to the pulmonary artery catheter in the ICU. The purpose of this study is to compare cardiac output measurement using two ultrasound-based technologies: TED vs TEE.

Methods

Twenty-one ventilated patients in septic shock were enrolled in two ICU units. The CO was recorded successively with TEE (COTEE) (Toshiba) and with TED (COTED) (Hemosonic 100 Arrow^® and DOPTEK-ODM^®) at the initial phase of septic shock. COTEE was obtained by measurement of the aortic velocity (ITVAo) in the transgastric view and by measurement of the aortic area in the transesophageal view (CSA): CSA × ITVAo × HR. An average of three measurements was recorded for each technique. A Bland-Altman study was used to compare the two techniques.

Results

Bad correlation was found between the two ultrasound-based technologies (correlation coefficient = 0.09; P = NS) with an overestimation of COTED on COTEE of 1.4 ± 5.4 l/min. These differences were found with the two Doppler types used.

Conclusion

Comparison of two non-invasive techniques to obtain CO output proves a low correlation between absolute value measurements of CO. Even though prolonged use is possible with TED, the absolute values obtained with TED have to be carefully interpreted.

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