Dexmedetomidine as an adjuvant to scalp block in patients undergoing elective craniotomy: A prospective randomized controlled trial.

Abstract

Regional techniques minimize anesthetic requirements and their effects may be beneficial. There is a lack of consensus and evidence concerning alternative analgesia strategies for cranial neurosurgery. This study was designed to evaluate the effect of scalp block with or without dexmedetomidine combined with general anesthesia on hemodynamic stability, opioid consumption and postoperative pain in patients undergoing elective craniotomy. One hundred five patients undergoing elective craniotomy for tumor dissection were randomly divided into three groups to receive scalp block as an adjuvant to general anesthesia: with either 40ml ropivacaine 0.5% (Group R), 40ml ropivacaine 0.5% plus dexmedetomidine 1μg/kg (Group RD) or 40ml saline as a placebo (Group C). After a standard induction sequence using propofol, fentanyl and a single dose of rocuronium, patients were intubated. Bilateral scalp block was given immediately after induction. Anesthesia was maintained with propofol and remifentanil infusion. Five minutes before head pinning scalp block was performed by blocking the supraorbital, supratrochlear, auriculotemporal, occipital, and postauricular branches of the greater auricular nerves. All patients were monitored with electrocardiogram, invasive blood pressure, pulse oximetry and BIS monitoring. Primary outcomes measures were overall hemodynamic variables during surgery and intravenous fentanyl and remifentanil consumption. Mean arterial pressure (MAP) and heart rate (HR) were recorded at seven time-points: scalp block (T1-baseline), pin fixation (T2), skin incision (T3), drilling (T4), dura matter incision (T5), dura matter closure (T6) and skin closure (T7). For all time points it was recorded the mean value after 3 consecutive measures with 5min interval. Secondary outcome was postoperative pain intensity using visual analog scale 24 and 48h after surgery. VAS scores, fentanyl and remifentanil were evaluated using Kruskal-Wallis test. MAP and HR were compared by One-Way repeated measures Anova (GLMM) using time as random efect and by One-Way Anova using time as fxed efect. Mean arterial pressure was significant lower at skin closure compared to baseline in group R (p<0,001) and in group RD (p<0,001). Patients in group RD showed significant lower heart rate at dura matter incision, dura matter closure and skin closure compared to baseline, pin fixation and skin incision time points (p<0,001) and reported significantly less heart rate than group C (p<0,001) and group R (p<0,001) during dura matter incision, dura matter closure and skin closure time points. Patients in group RD receive significant lower fentanyl than group R (p<0,01). The intraoperative consumption of remifentanil was significant higher in control group compared to group R (p<0,01) and to group RD (p<0,001). Additionally, remifentanil consumption was significant lower in group RD as compared to group R (p<0,001). Postoperative pain had no statistically differences between the three groups at 24h and 48h after craniotomy (Preop VAS: p=0,915, VAS 24: p=0,284, VAS 48, p=0,385). No adverse effects were noted. Our study indicated that addition of dexmedetomidine to scalp block with ropivacaine 0.5% provided significantly better perioperative hemodynamic stability during elective craniotomy. Moreover, scalp block with or without dexmedetomidine reduced fentanyl and remifentanil consumption, but it didn't significantly prolonged analgesia in patients undergoing elective craniotomy.