Transesophageal echocardiographic hemodynamic monitoring during preoperative acute normovolemic hemodilution

Background: Preoperative acute normovolemic hemodilution may compromise oxy gen transport. The aims of our study were to describe the hemodynamic effec ts of normovolemic hemodilution and to determine its effect on systolic and diastolic cardiac function by multiplane transesophageal echocardiography. Methods: In eight anesthetized patients (aged 13-51 yr) without heart disea se, hemoglobin was reduced in steps from 123 +/- 8 (mean +/- SD) to 98 +/- 3 and to 79 +/- 5 g/l. Hemodynamic measurements (intravascular pressures, t hermodilution cardiac output, and echocardiographic recordings) were obtain ed during a stabilization period and at each level of hemodilution, Left ve ntricular wall motion was monitored continuously, and Doppler variables, an nular motion, and changes in ejection fractional area were analyzed off-lin e. Results: During hemodilution, cardiac output by thermodilution increased by 16 +/- 7% and 26 +/- 10%, corresponding well to the increase in cardiac ou tput as measured by Doppler (difference, 0.32 +/- 1.2 1/min). Systemic vasc ular resistance fell 16 +/- 14% and 23 +/- 9% and pulmonary capillary wedge pressure increased slightly (2 +/- 2 mmHg), whereas other pressures, heart rate, wall motion, and diastolic Doppler variables remained unchanged. Eje ction fractional area change increased from 44 +/- 7% to 54 +/- 10% and 60 +/- 9% as a result of reduced end-systolic and increased end-diastolic left ventricular areas. Conclusions: A reduction in hemoglobin to 80 g/l during acute normovolemic hemodilution does not normally compromise systolic or diastolic myocardial function as determined by transesophageal echocardiography, Preload, left v entricular ejection fraction, and cardiac output increase with a concomitan t fall in systemic vascular resistance.