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.