evidence: We find the ED50 were lower, and the ED50 of 0.5% hypobaric bupivacaine and ropivacaine was 4.66 mg (95% CI 4.69–4.63 mg) and 6.43 mg (95% CI 6.47–6.39 mg),
intervention: intrathecal 0.5% hypobaric bupivacaine USpA (group B)
comparator: 0.5% hypobaric ropivacaine USpA (group R)
outcome: the median effective dose (ED50) of 0.5% hypobaric bupivacaine