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 g of fentanyl, and in the low-dose bupivacaine with high-dose fentanyl (LBHF) group, 6 mg of bupivacaine and 50 g 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 141.228.9 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 248.231.4 and 282.128.6 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 g) was faster and longer. On the other hand, the duration of analgesia in the low-dose bupivacaine (6 mg) and high-dose fentanyl (50 g) was higher.