Efficacy and safety of intrathecal pentazocine as a sole anesthetic agent for lower limb surgeries

CONTEXT: The administration of opioids intrathecally as a sole anesthetic has proven to be effective in providing adequate surgical anesthesia without much hemodynamic instability. AIM: This study aims to determine the efficacy and safety of intrathecal pentazocine as a sole anesthetic drug in patients undergoing lower limb surgeries. SETTINGS AND DESIGN: It was a randomized single blinded study conducted in 60 patients undergoing lower limb surgeries. SUBJECTS AND METHODS: The patients were randomly divided into 2 groups of 30 patients in each group. Group A received 2 ml (60 mg) intrathecal pentazocine and Group B received 2 ml intrathecal 0.5% bupivacaine heavy before surgery. Duration of surgery, onset of sensory, and motor blockade and their duration, heart rate (HR), mean arterial pressure (MAP), and time for first rescue analgesia were statistically analyzed. RESULTS: Group B showed a statistically significant earlier onset of sensory (2.54 ± 0.87 vs. 3.66 ± 1.10 min) and motor blocks (2.22 ± 0.77 vs. 3.29 ± 1.06 min). The majority of patients in the group A (30%) attained the highest level of sensory block of T11, whereas the majority in group B (33.3%) attained the highest level of sensory block of T8. Majority in the Group A (60%) showed a motor block of Bromage scale Grade III at the beginning of surgery, whereas the majority in Group B (80%) showed a motor block of Bromage scale Grade IV. Duration of sensory block was significantly prolonged in group B (124.33 ± 14.84 vs. 115.60 ± 18.39 min). However, duration of motor blockade was similar in both groups. Group B patients required first analgesia earlier than Group A (5.24 ± 1.98 h vs. 2.48 ± 0.51 h) which was significant. There was no difference between groups with regard to HR intra-operatively. On comparison of the pre-induction MAP between 2 groups, there was no difference. But later on at 1, 3, 5 min intervals, the MAP was less in group B. But at 10 and 15 min there was no significant difference between groups. The significantly reduced MAP in group B was evident again at 30, 45, and 60 min. There was no difference between groups at 90 and 120 min. Group B required first analgesia earlier than group A which was statistically significant. CONCLUSIONS: Because of adequate surgical anesthesia, intraoperative hemodynamic stability and prolonged post-operative analgesia, we recommend the use of intrathecal pentazocine as a sole anesthetic agent for lower limb surgeries.