low-dose bupivacaine versus high-dose bupivacaine along with fentanyl for spinal anesthesia in opioid-dependent mothers

Background: spinal anesthesia is the method of choice for cesarean section. in opioid-dependent mothers, more narcotic is necessary for analgesia. objectives: in this study, low dose bupivacaine was used to reduce adverse effects, and high dose fentanyl was used to improve analgesia. patients and methods: this randomized double-blinded study was performed on 60 opioid-dependent pregnant females in 2 similar groups. in the high-dose bupivacaine with low-dose fentanyl (hblf) group, 10 mg of bupivacaine and 25 µg of fentanyl, and in the low-dose bupivacaine with high-dose fentanyl (lbhf) group, 6 mg of bupivacaine and 50 µg of fentanyl were used for spinal anesthesia. the blood pressure, heart rate, itching, nausea and vomiting, apgar score at 1 and 5 minutes, and surgeon and patient satisfaction were evaluated during the study. the sensory block onset and reverse were measured to thorax 5 and thorax 12, respectively. the patient’s pain was assessed by a verbal analogue scale (vas) every half an hour. the time of analgesic was determined from anesthesia injection to verbal analogue scale of > 4. the information was analyzed using the spss v16 software and p < 0.05 was considered significant. results: the demographic data and pre-anesthetic hemodynamic status were similar. the blood pressure was decreased in both groups (p = 0.019), yet there was no significant difference between the 2 groups (p = 0.43). there was no difference in heart rate (p = 0.33), itching, nausea, and vomiting, apgar score at 1 and 5 minutes, and surgeon and patients’ satisfaction, (p value was 0.47, 0.54, 0.85, 0.86, 0.92, and 0.09, respectively). the block onset to t5 in the hblf group and lbhf group was 4.4 ± 0.9 and 5.3 ± 0.9 minutes, respectively (p = 0.002). the sensory block reverse to t12 in the hblf group and the lbhf group was 141.2 ± 28.9 and 122.3 ± 24.5 minutes, respectively (p = 0.03). also, the time of the first analgesic in the hblf group and the lbhf group was 248.2 ± 31.4 and 282.1 ± 28.6 minutes, respectively (p = 0.02). conclusions: there was no difference between low-dose and high-dose narcotic groups in complications and satisfaction. in the opioid-addicted mothers, the sensory block at high-dose bupivacaine (10 mg) and low-dose fentanyl (25 µg) was faster and longer. on the other hand, the duration of analgesia in the low-dose bupivacaine (6 mg) and high-dose fentanyl (50 µg) was higher.