[Comparison of the effects of colloid and crystalloid solution for volume preloading on maternal hemodynamics and neonatal outcome in spinal anesthesia for cesarean section]

BACKGROUND: The role of crystalloid or colloid preloading to prevent hypotension associated with spinal anesthesia in parturients during cesarean section has recently been questioned. The aim of the current study was to investigate the effects of volume preload with either crystalloid or colloid, or with no preload on changes of maternal hemodynamics and neonatal outcomes.

METHODS: After written informed consent had been obtained from each patient, thirty-two healthy parturients undergoing cesarean section were randomized to receive either acetated Ringer's solution (1,000 ml, n=8, AR group), 6% hydroxyethylstarch (1,000 ml, n=9, HES group), or no preload (n=10) before spinal anesthesia. In addition, emergency cases (n=5) such as prolonged labor without any maternal complication were also included for analysis. The incidence of hypotension, systolic blood pressure <80% of baseline or <100 mmHg, and the amount of ephedrine used to treat hypotension were compared. Neonatal outcome was also assessed measuring pH and lactate concentration in umbilical arterial blood samples. Apgar score was also measured at 1 and 5 min after delivery.

RESULTS: There was no difference in demographic characteristics among the four groups. Minimal systolic arterial pressure (SAP) after spinal anesthesia did not differ among AR, HES, and no preload groups. However, a significant decline in SAP was observed in emergency group (82.2 +/- 14.3 mmHg, P<0.05). Although there was no difference in umbilical arterial blood pH, lactate concentration was significantly higher in emergency group (3.7 +/- 1.0 mmol x l(-1), P<0.01) than those of other groups. Apgar score at 1 min after delivery was significantly lower in emergency group.

CONCLUSION: In healthy patients with full-term pregnancy, volume preloading has little effect on maternal hemodynamics and neonatal outcomes, suggesting that stable perioperative management is possible with or without volume preload before spinal anesthesia. However, preloading may be needed for prevention of hypotension in emergency cases.