Influence of a prolonged lateral position on induction of spinal anesthesia for cesarean delivery: a randomized controlled trial

Background. Maternal hypotension occurs commonly during cesarean delivery under spinal anesthesia. We evaluated whether hypotension due to aortocaval compression could be prevented by maintaining a lateral position after an intrathecal injection. Methods. Eighty-six women undergoing elective cesarean delivery were enrolled. Spinal anesthesia was conducted in the right lateral position using 8 mg of hyperbaric bupivacaine and 15 mu g of fentanyl. Patients were randomly assigned to maintain the right lateral position for 6 min before assuming the wedged supine position (group L), or to assume the wedged supine position immediately after the spinal injection (group S). Hypotension was defined as a decrease in mean arterial pressure to <80% of baseline. Ephedrine was given if blood pressure decreased to <70% of baseline. The incidence of hypotension and nausea, ephedrine requirement, maximal block height, and neonatal outcomes were evaluated. Results. No significant between-group differences were observed in the lowest blood pressure, total ephedrine dose, or incidence of hypotension or nausea. Onset of hypotension was delayed (6 2 vs. 10 3 min, P<0.001), and the sensory block level was more cephalad in group L than in group S (T2 [C8-T5] vs. T4 [T1-T6], P=0.001). Apgar scores did not differ between the groups. Conclusion. During spinal anesthesia for elective cesarean delivery, maintaining the lateral position for 6 min after an intrathecal injection of hyperbaric bupivacaine resulted in a more gradual and higher cephalad sensory block, without an increase in the incidence of maternal hypotension. (Minerva Anestesiol 2012;78:646-52)