[Preload during spinal anesthesia for cesarean section: comparison between crystalloid and colloid solutions.]

Maternal hypotension is the most common complication following spinal anesthesia for cesarean section. This study aimed at comparing the incidence of hypotension and the need for vasopressors in patients submitted to cesarean section under spinal anesthesia following preload with either crystalloid or colloid (modified fluid gelatin).

Participated in this prospective study 50 term pregnant patients, physical status ASA I, submitted to cesarean section under spinal anesthesia. Patients were randomly allocated into two groups receiving preload as follows: Crystalloid group, 10 mL.kg-1 lactated Ringer; Colloid group, 10 mL.kg-1 colloid (modified fluid gelatin). Control blood pressure was defined as the mean of three successive systolic blood pressure (SBP) values. SBP was measured at 1-minute intervals and 0.2 mg intravenous bolus of metaraminol was administered for SBP decrease above 10% of control blood pressure, and 0.4 mg bolus of the same drug for SBP decrease above 20% of control. Apgar score was evaluated after delivery and umbilical artery blood was sent for analysis. Modified Student's t test was used for statistical analysis and p < 0.05 was considered statistically significant.

Hypotension 10% (100% and 100% of patients); hypotension 20% (72% and 72% of patients), nausea (4% and 8% of patients); vasopressor consumption (1.67+/- 0.89 mg and 1.88 +/- 0.74 mg) and umbilical artery pH (7.25 +/- 0.04 and 7.26 +/- 0.04), in Crystalloid and Colloid groups, respectively, were similar.

In the conditions of this study, colloid (modified fluid gelatin) was equivalent to crystalloid (lactate Ringer) in preventing or decreasing the incidence of hypotension in patients submitted to cesarean section under spinal anesthesia.