To confirm whether the descending aortic blood flow velocity waveform variable of flow time corrected for heart rate, measured using an esophageal Doppler transducer, can be used for noninvasive optimization of left ventricular (LV) filling.Setting
ICU and operating theater.Subjects
Forty-three mechanically ventilated patients in the ICU or undergoing cardiothoracic surgery in whom a pulmonary arterial catheter was in situ.Interventions
LV preload was a) increased from hypovolemic states (pulmonary arterial occlusion pressure [PAOP] <8 mm Hg) by fluid challenge, b) decreased from normovolemic states (PAOP 10 to 15 mm Hg) by either iv nitrates or intravascular fluid loss, and c) decreased from heart failure or fluid overload states (PAOP <20 mm Hg) by iv nitrates. No other maneuver was performed concurrently.Measurements and Main Results
Descending aortic blood flow was measured by an esophageal Doppler transducer. Corrected flow time was calculated by dividing systolic flow time by the square root of the cycle time. PAOP and corrected flow time increased after fluid challenges in hypovolemic states, and decreased when LV preload was decreased from normovolemic states. However, when preload was decreased from overload states, PAOP always decreased, but the corrected flow time usually increased before any subsequent decrease. The greatest value of corrected flow time corresponded with the maximal stroke volume seen.Conclusions
Esophageal Doppler measurement of aortic blood flow can be used for rapid, noninvasive optimization of LV filling in mechanically ventilated patients.