question: Compared to 0.5% hypobaric ropivacaine USpA (group R) what was the result of intrathecal 0.5% hypobaric bupivacaine USpA (group B) on the median effective dose (ED50) of 0.5% hypobaric bupivacaine?
context: 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),