Abstract PR152

Abstract

Background & Objectives: Awake craniotomies for tumor resection are characterized by alternating asleep-awake-asleep periods. Preceding the awake phase, patients are weaned from anesthesia and mechanical ventilation. Although it is aimed to minimize the time to awake in order to save surgical time, in some patients the time to awake exceeds 20 minutes. In this retrospective study we investigated patient factors that are of influence on the time to awake during awake craniotomy. Materials & Methods: We retrospectively evaluated the medical files of patients who underwent an awake craniotomy between 2003 and 2013 in the VU University Medical Center in Amsterdam, the Netherlands. Anesthesia was induced according to protocol using propofol 2.5mg/kg, remifentanil 50ug kg-1 hr-1 and mivacurium 0.2mg/kg, and maintained with propofol 6mg kg-1 hr-1, remifentanil at 15-25ug kg-1 hr-1 and mivacurium at a dose which gave 1 twitch on the train of four monitor (TOF-Watch®). Time to awake was defined as the time between interruption of propofol and remifentanil infusion and the time of detubation. Patient characteristics including age, body mass index, smoking, alcohol or drugs intoxication, preoperative use of dexamethasone and use of anti-epileptics were retrieved from medical records. Data were analyzed using univariate and multinominal logistic regression analyses. Results: Between 2003 and 2013, 132 patients underwent awake craniotomy. The mean age was 39 ± 11 years and 57% were male. The average time to awake was 15 ± 9 minutes. The time to awake exceeded 20 minutes in 15% of the patients. Univariate logistic regression analysis revealed patient age as predictor for a time to awake ≥ 21 minutes (odds ratio 1.055 per year; 95% CI 1.009–1.104). The preoperative use of dexamethasone tended to be associated with an increased odds ratio for a prolonged time to awake (OR 3.219; 95% CI 0.868–11.938; P=0.08). In contrast, smoking was associated with a reduced odds ratio for a prolonged time to awake (0.197; 95% CI 0.044–0.894; P=0.035). Multinomial logistic regression revealed that age (OR 1.05; 95% CI 1.003–1.101; P=0.035) and smoking (OR 0.211; 95% CI 0.046–0.978; P=0.047) were independently associated with the time to awake. Body mass index, use of alcohol, drugs or anti-epileptics was not associated with the time to awake. Conclusion: A time to awake exceeding 20 minutes occurred in 15% of the cases. Increased age prolonged the time to awake, while smoking reduced the time to awake. In contrast to our expectations, body mass index or the use of alcohol, drugs or anti-epileptics were not associated with the time to awake. Disclosure of Interest: None declared