Bupivacaine scalp nerve block: hemodynamic response during craniotomy, intraoperative and post-operative analgesia

Background: Noxious stimuli during craniotomy may induce hypertension and tachycardia, giving rise to morbidity in patients with intracranial hypertension. Craniotomy is followed by moderate level of postoperative pain. Objective: Evaluate the effectiveness of scalp block on hemodynamic response to noxious stimuli, intraoperative fentanyl requirement and post-operative analgesia. Methods: Sixty patients undergoing elective craniotomy were randomly assigned to receive a scalp block with either 0.5% bupivacaine or 0.25% bupivacaine and 1:200,000 adrenaline (group A and B) or normal saline with 1:200,000 adrenaline (group C). Fentanyl 0.5 mcg/kg was administered for hemodynamic control. Intraoperative mean arterial blood pressure (MAP), heart rate (HR), fentanyl doses, and post-operative pain scores were recorded. Post-operative analgesia was provided by patient-controlled analgesia (PCA) morphine for 24 hours. Results: MAP was greater in group C than group A during pinning and incision (p <0.05), and was greater in group C than group B during pinning, incision and craniotomy (p <0.05). HR differences were not statistically significant between all groups (p >0.05). Intraoperative fentanyl requirement was significantly greater in group C compared with group A and B (p <0.05). Pain score, time to the first morphine administration and total morphine consumption were not significantly different between all groups. Conclusion: Pre-incision scalp blocks using either 0.25% or 0.5% bupivacaine with 1:200,000 adrenaline were effective to prevent rising of MAP, but not HR in response to cranial pinning and skin incision, causing less intraoperative fentanyl requirement. However, they did not reduce post-craniotomy pain and morphine consumption.