Effect of Fentanyl on Block Characteristics as Adjuvant to Intrathecal Bupivacaine for Lower Limb Surgeries

Regional anesthesia is the preferred technique for most of lower abdominal and lower limb surgeries as it allows the patient to remain awake and minimize the problems associated with airway management. Hyperbaric bupivacaine 0.5%, although extensively used for spinal anesthesia, has a limitation of short duration. The addition of fentanyl, a synthetic lipophilic opioid, is known to prolong postoperative analgesia.

We aimed to study the effect of the addition of different doses of fentanyl to hyperbaric bupivacaine about hemodynamic changes, the extent of sensory and motor block, duration of analgesia, and complications that occur during the procedure.

This study was a prospective, comparative, randomized, and double-blind study.

Patients were randomly allocated to three groups of 30 each. Group I (n [number of patients] = 30) received bupivacaine 0.5% heavy 2.0 mL diluted up to 2.5 mL with normal saline. Group II (n = 30) received bupivacaine 0.5% heavy 2.0 mL and fentanyl 20 μg diluted up to 2.5 mL with normal saline, and Group III (n = 30) received bupivacaine 0.5% heavy 2.0 mL and fentanyl 50 μg diluted up to 2.5 mL with normal saline.

The data were analyzed using Chi-square and Student's t-test.

The onset of sensory and motor block was early in Group III in comparison to Group I and Group II (P < 0.05). The duration of analgesia was significantly longer in Group III, followed by Group II, and least in Group I. None of the patients in Groups I and II had any complications such as hypotension, nausea, vomiting, bradycardia, and pruritus. However, the incidence of hypotension, nausea, and pruritus was more in Group III. 2 mg intrathecal bupivacaine with 20 μg fentanyl provides reliable and satisfactory sensory and motor block without increasing the incidence of side effects.