Influence of crystalloid and colloid replacement solutions on hemodynamic variables during acute normovolemic hemodilution

Study Objective: To determine whether, in maintaining normovolemia during acute normovolemic hemodilution, replacement fluid choice influences intraoperative hemodynamic variables. Design: Prospective, randomized, single-blinded study. Setting: Operating room of a tertiary-care university hospital. Patients: 40 adult, ASA physical status I, II, and III patients scheduled for acute normovolemic hemodilution during radical prostatectomy. Interventions: Patients were randomly assigned to four replacement fluid groups to receive 1) Ringer's lactate, 2) 5% albumin, 3) 6% dextran 70, or 4) 6% hetastarch. A standardized general anesthetic was used, and patients underwent moderate hemodilution to a target hemoglobin of 9 gm/dL. Measurements: Hemodynamic variables were recorded using standard monitors, 5-lead electrocardiography, radial arterial catheter, and pulmonary artery catheter. Red blood cell loss for the entire hospitalization was calculated. Main Results: Demographic and clinical outcome data were similar among the groups. During acute normovolemic hemodilution, heart rate and pulmonary capillary wedge pressure were unchanged from baseline in all groups, but patients receiving Ringer's lactate or albumin had greater declines in mean arterial pressure at the end of acute normovolemic hemodilution. Cardiac and oxygen consumption indexes were stable during acute normovolemic hemodilution, but oxygen extraction increased. Conclusions: During hemodilution, anesthetized patients maintain whole body oxygenation by increasing oxygen extraction. The administration of hetastarch or dextran as the replacement fluid during acute normovolemic hemodilution is associated with a more stable mean arterial pressure, but overall acute normovolemic hemodilution is well tolerated irrespective of the replacement fluid used.