Appropriate dose of isobaric bupivacaine with fentanyl in spinal anesthesia for cesarean section

BACKGROUND: Spinal anesthesia combined with fentanyl is commonly used for cesarean section. We studied the appropriate dose of isobaric bupivacaine for spinal anesthesia when combined with a fixed dose of 20 microg fentanyl. METHODS:Forty-seven women scheduled for cesarean section were allocated into four-groups according to the dose of 0.5% isobaric bupivacaine with 20 microg fentanyl; 1.0 ml (n=5), 1.5 ml (n=11), 2.0 ml (n=11), and 2.5 ml (n=20). RESULTS: The requirement of epidural anesthesia for pain relief or muscle relaxant was less in the 2.0 ml and 2.5 ml groups than the other groups. However, dyspnea due to high spinal anesthesia developed in 3 subjects out of 20 in the 2.5 ml group. CONCLUSIONS: Two ml of 0.5% isobaric bupivacaine was the most appropriate dose for cesarean section, when combined with 20 microg of fentanyl.