HEMODYNAMIC-EFFECTS OF MODERATE NORMOVOLEMIC HEMODILUTION IN CONSCIOUS AND ANESTHETIZED PATIENTS

We have assessed the haemodynamic effects of moderate normovolaemic ha emodilution in ASA patients, either conscious or during enflurane-fent anyl anaesthesia (10 patients in each group). Cardiac index (CI), stro ke index (SI) and ejection fraction (EF) were measured by transthoraci c electrical bioimpedance and, in the anaesthesia group, arterial and central venous blood samples were obtained to assess oxygen delivery ( DO2), oxygen consumption (V overdot O-2) and oxygen extraction ratio ( O(2)ER). In conscious patients, heart rate (HR) remained unchanged as SI, EF and CI increased. When haemodilution was performed during anaes thesia, CI remained stable in spite of a slight increase in SI, as HR decreased. This produced a reduction in DO2 which was compensated for by an increase in O(2)ER, allowing maintenance of V overdot O-2 withou t alteration in blood lactate concentration.