Maternal and fetal effects of prophylactic hydration with crystalloids or colloids before epidural anesthesia

Prophylactic intravenous hydration decreases the incidence and severity of hypotension due to obstetric epidural anesthesia. This study assesses whether infusion of normal serum albumin (NSA) offers any advantages over Ringer's lactate (RL) solution. Sixty patients scheduled for elective cesarean sections were divided into three equal groups. Group 1 received 1200 ml of RL; group 2, 700 ml of RL plus 500 ml of 5% NSA; and group 3, 1000 ml of RL plus 200 ml of 25% NSA. In group 1, the concentrations of serum albumin (SA) decreased from 3.5 +/- 0.3 (mean +/- SD) to 3 +/- 0.2 g/dL (P less than 0.01) and plasma oncotic pressure (POP) from 20 +/- 3 to 17 +/- 3 torr (P less than 0.005) immediately after hydration. In group 2, SA remained unchanged, but POP decreased from 21 +/- 2 to 19 +/- 2 torr (P less than 0.005). In group 3, SA increased from 3.6 +/- 0.5 to 3.9 +/- 0.3 g/dL (P less than 0.01) and POP from 19 +/- 2 to 21 +/- 2 torr (P less than 0.0025). Neither SA nor POP levels differed among the groups 24 h later; however, both SA and POP were significantly lower than preinfusion values in all groups at 24 h. The incidence of maternal hypotension, neonatal Apgar scores, and acid-base status also were comparable among the groups (X2 analysis). Because low POP may predispose to postoperative pulmonary morbidity, the incidence of this complication was studied in the mothers by using a point scoring system (based on the presence of symptoms and physical signs) and also by measuring AaDO2 gradients. Neither pulmonary morbidity scores nor AaDO2 gradients differed significantly in the three groups. It is concluded that both crystalloid and colloid prehydration produce equally satisfactory maternal and fetal outcomes.