HEMODYNAMIC CONSEQUENCES AND UTERINE CONTRACTIONS FOLLOWING 0.5 OR 1.0 LITER CRYSTALLOID INFUSION BEFORE OBSTETRIC EPIDURAL ANALGESIA

Purpose: The efficacy of infusion of 0.5 L and 1.0 L Ringer's lactate (LR) to prevent hypotension during induction of obstetric analgesia wa s studied The effect of the different fluid boluses on fetal heart rat e (FHR) and frequency of uterine contractions were also determined. Me thods: Ninety-two ASA 1-2 parturients were randomized to receive 0.5 L (Group 1) and 1.0 L (Group 2) LR immediately before incremental epidu ral injections with lidocaine to achieve T-10 sensory block. Systolic blood pressure (SBP) was measured with an automated BP cuff every two minutes for 30 min after infusion of fluid bolus. Fetal heart rate mon itoring and tocometry were used continuously. The number of uterine co ntractions were recorded 30 min before and 60 min after iv bolus. Resu lts: The SBP decreased in both groups, but there was no difference bet ween groups in mean SBP or maternal heart rate. The incidence of hypot ension (SBP < 90 mmHg or decrease of 20%) was 4% in both groups. The F HR record of a patient in Group 1 showed a single late deceleration, a nd a decrease in bear-to-beat variability occured in one patient ill G roup 2. A decrease in the frequency of uterine contractions of two or more contractions per 30 min was noted more frequently in Group 2 (P < 0.05). The duration of iv bolus was longer in Group 2 than Group 1 (1 8.8 +/- 4.3 min vs 12.3 +/- 4.5 min, P < 0.01). Conclusion: Administra tion of 1.0 L LR iv does not provide added protection against maternal hypotension, and is associated with delay in providing pain relief an d a risk of decreasing uterine contraction frequency.