Maternal hypotension and fetal outcome: effect of height-adjusted and weight-adjusted dose versus fixed dose of 0.5% intrathecal hyperbaric bupivacaine

Abstract

Background Profound hypotension during cesarean section can compromise fetal circulation and cause cardiac arrest in the parturients. We compared the incidence of hypotension, adequacy of anesthesia, and neonatal outcome using a height-adjusted and weight-adjusted dose and a fixed dose of 0.5% intrathecal hyperbaric bupivacaine. Patients and methods This was a randomized controlled double-blind trial involving 80 parturients aged 18–40 years scheduled for elective cesarean section under spinal anesthesia. They were randomly allocated by blind balloting into one of two groups: group FD received 12 mg of 0.5% hyperbaric bupivacaine, whereas group AD received a height-adjusted and weight-adjusted dose of 0.5% hyperbaric bupivacaine according to Harten’s chart. Parturients were preloaded with 10 ml/kg of 0.9% sodium chloride. Results The median dose of bupivacaine was significantly higher in group FD (12 mg) than group AD (9.5 mg) (P=0.001). The incidence of hypotension was significantly higher in group FD (60%) than in group AD (32.5%) (P=0.014). The median time to attain the maximal level of sensory block (T5) was significantly faster in group FD (10 min) than group AD (13 min) (P=0.021). The Apgar score and incidences of other complications were comparable between both groups (P>0.05). Conclusion It is concluded that a lower dose of bupivacaine was required to provide comparable sensory and motor block, with less incidence of hypotension when the bupivacaine dose was adjusted to the height and weight of parturients than when a fixed dose was used.