We performed this study to summarize drug dosing, physiologic responses, and anesthetic complications from an IV general anesthetic technique for patients undergoing craniotomy for awake functional brain mapping. Review of 98 procedures revealed "most rapid" IV infusion rates for remifentanil 0.05, 0.05-0.09 microg x kg(-1) x min(-1) and propofol 115, 100-150 microg x kg(-1) x min(-1). The infusions lasted for 78, 58-98 min. Intraoperative emergence from general anesthesia was 9 (6-13) min after discontinuing IV infusions to allow for brain mapping and was independent of infusion duration and duration of craniotomy before mapping. Spontaneous ventilation was generally satisfactory during drug infusion, as evidenced by Sao(2) = 95% (92%-98%) and Paco(2) = 50 (47-55) mm Hg. However, we recorded at least one 30-s epoch of apnea in 69 of 96 patients. Maximum systolic arterial blood pressure was 150 (139-175) mm Hg and minimal systolic arterial blood pressure was 100 (70-150) mm Hg during drug infusion. Three patients experienced intraoperative seizures. Two patients did not tolerate the awake state and required reinduction of general anesthesia. No patients required endotracheal intubation or discontinuation of surgery. This general anesthetic technique is effective for craniotomy with awake functional brain mapping and offers an alternative to continuous wakefulness or other IV sedation techniques.
Implications: An IV general anesthetic technique using remifentanil and propofol is an effective method allowing for reliable emergence for intraoperative awake functional brain mapping during craniotomy.