Factors Affecting Time to Emergence From General Anesthesia Following Clipping of Ruptured Aneurysms: A Prospective Observational Study

Introduction: Early emergence from anesthesia is valuable, especially among neurosurgical patients for postoperative neurological evaluation and appropriate interventions. However, the factors affecting the emergence in patients undergoing clipping of ruptured aneurysms have not been studied. Materials and Methods: This was a prospective observational study on patients of aneurysmal subarachnoid hemorrhage with World Federation of Neurological Surgeons (WFNS) Grades I to III, undergoing surgical clipping. All relevant preoperative and intraoperative details were collected and analyzed to assess the factors affecting emergence time. Results: A total of 67 patients with a median age of 46 years were included in the study. The number of patients with Fisher Grades I, II, III, and IV was 6, 20, 25, and 16, respectively. The median time to emergence was 17 minutes (interquartile range 10-240 minutes). On univariate analysis, the factors that were found to have a significant relationship with time to emergence were preoperative Glasgow Coma Score (GCS; P = 0.02), WFNS grade (P = 0.005, temporary clipping time (P = 0.03), and the temperature at the end of surgery (P < 0.001) In the multivariate analysis using generalized linear model, preinduction GCS (P < 0.001), patient's temperature at the end of surgery (P < 0.001), and temporary clipping time (P = 0.01) had a significant impact on the emergence time, independent of age, American Society of Anesthesiologists grade, Fisher grade, duration of anesthesia and of each other, with GCS and temperature having the maximum impact. ROC curve for temperature had a cutoff value at 35.3 degrees C with an 83% probability of awakening beyond 15 minutes if the temperature decreased below 35.3 degrees C. Conclusion: The preinduction GCS, the temperature of patients at the end of surgery, and the duration of temporary clipping have a significant independent impact on the time to emergence from neurosurgical anesthesia, in the order of the strength of the association.