Comparative Evaluation of analgesic efficacy of ketamine and magnesium sulfate as adjuvants to bupivacaine for scalp block in supratentorial Craniotomy: A Randomized, Double-Blind clinical study

Background

Effective pain management during craniotomy is crucial for optimizing hemodynamics, recovery, and patient satisfaction. This study evaluated the efficacy of ketamine and magnesium sulfate as adjuvants to bupivacaine in preemptive scalp blocks, focusing on hemodynamics, postoperative pain, and analgesic consumption.

Methods

This study included 102 patients undergoing supratentorial craniotomy, randomized into three groups (n = 34 in each): Group K (ketamine), Group M (magnesium sulfate), and Group C (saline). Each group received a preemptive scalp block with bupivacaine with the respective adjuvants. Hemodynamics, postoperative pain (Critical-Care Pain Observation Tool, CPOT), and analgesic consumption were measured at various time points.

Results

Ninety-seven patients were analyzed. Scalp block reduced the hemodynamic response to pin insertion in all groups. Intra-operative fentanyl consumption was significantly lower in the ketamine (191.82 ± 53.18 µg) compared to the saline (304.06 ± 48.73 µg) and magnesium groups (275.31 ± 59.04 µg, p < 0.001). The time (hours) to the first post-operative analgesic demand was longer in the ketamine (12.97 ± 4.13) compared to the saline (3.03 ± 1.47) and magnesium groups (4.19 ± 1.45, p < 0.001). Ketamine resulted in the lowest CPOT scores at 4 h (0.30 ± 0.53) post-operatively compared to magnesium (1.12 ± 0.66) and saline (1.66 ± 0.55, p < 0.001).

Conclusions

Scalp block, with or without adjuvants, is effective in managing pin response. This study highlights ketamine as a valuable adjuvant to bupivacaine, significantly reducing analgesic consumption and prolonging pain relief. Magnesium provides moderate benefits. These findings support the preemptive use of ketamine in scalp block to enhance analgesia and maintain hemodynamic stability during craniotomy. However, further studies are needed to correlate the serum levels of ketamine to identify whether the effect is as adjuvant to local anesthetic or due to its systemic absorption.