A Prospective Randomized Controlled Study to Analyze the Efficacy of Scalp Block in Providing Analgesia for Supratentorial Craniotomies Using Surgical Pleth Index, Response Entropy, and Hemodynamics

Background: Supplementing general anesthesia with regional technique has markedly improved intraoperative hemodynamics and intraoperative analgesia. We compared the effects of scalp block (study group) and no scalp block (control group) on intraoperative hemodynamics and correlated surgical plethysmographic index with other variables like response entropy, state entropy and mean arterial pressure to assess the depth of analgesia.

Materials and Methods: In this prospective study, a total of 30 ASA physical grade-1 and -2 patients, satisfying the inclusion criteria, undergoing supratentorial craniotomies were double blinded, and divided into two groups (study group, control Group).Study group received 0.2% ropivacaine 20 mL for scalp block and control group received 20 mL normal saline for scalp block and for both the groups received fentanyl infusion at 1 µg/kg/h. Intraoperatively injection fentanyl (1 µg/kg) was given as rescue analgesia when there was >20% raise in hemodynamics above baseline. Quality of analgesia was assessed by using surgical plethysmographic index, response entropy and state entropy at different time points (induction, postinduction, intubation, postintubation, pin, postpin, incision, postincision, craniotomy, postcraniotomy, durotomy, and postdurotomy).

Results: We found that patients in study group had stable intraoperative hemodynamics with decrease in requirement of intraoperative fentanyl. Intraoperative fentanyl consumption (in µg/kg) was decreased in in study group (0.06 ± 0.04) compared with control group (1.73 ± 0.52). We found that surgical plethysmographic index, response entropy, state entropy, and mean arterial pressure positively correlated intraoperatively as depth of analgesia monitors.

Conclusion: We conclude that scalp block when given along with general anesthesia can offer better intraoperative hemodynamic stability and decreased intraoperative fentanyl requirement. Surgical plethysmographic index, response entropy, and static entropy correlated well as depth of analgesia monitors.

Publication History

Article published online:
25 March 2020