A prospective, randomized controlled trial comparing the left lateral, modified lateral and sitting positions for...

Maternal position affects spinal block characteristics. We investigated the effect of lateral, modified lateral and sitting position for spinal anesthesia with 2 mL hyperbaric bupivacaine 0.5% on spinal block characteristics in this prospective, randomized study.

Seventy-five ASA physical status I parturients were randomly allocated to the left lateral to supine-wedged, modified lateral to supine-wedged with a10°head-up tilt or the sitting to supine-wedged position for induction of spinal anesthesia for Cesarean delivery. Neural block was assessed by pin prick and modified Bromage scale. Data were analyzed using ANOVA, Chi-square test and Wilcoxon rank sum test, where appropriate. P<0.05 was considered significant.

Onset time (mean ± SD) for sensory block to T5 dermatome for the lateral, modified lateral and sitting groups was 6.8 ± 2.7, 13.6 ± 6.2 and 9.7 ± 5.5 min, respectively; P<0.001. The median (interquartile range) maximum dermatomal level was significantly lower in the modified lateral group (T5[T3-T5]) compared with the lateral (T3[T2-T4]) and sitting (T3[T3-T4]) groups, respectively; P=0.022 and P=0.030, respectively. Three women in the modified lateral group required general anesthesia compared with none in the other groups; P= 0.044. Apgar scores and cord blood pH, PO2 and PCO2 were similar between groups.

The modified lateral position with 10 mg of hyperbaric bupivacaine was associated with a slower onset and a lower maximum sensory block necessitating higher requirement for conversion to general anesthesia. It did not offer any advantage over lateral and sitting positions for induction of spinal anesthesia for elective Cesarean delivery and cannot be recommended.