The Recovery of Cognitive Function After Remifentanil- Nitrous Oxide Anesthesia Is Faster than After an Isoflurane-Nitrous Oxide-Fentanyl Combination in Elderly Patients

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Abstract
We tested the hypothesis that remifentanil-nitrous oxide (N2O) anesthesia shortens postoperative emergence and recovery compared with an isoflurane-N2O-fentanyl combination in elderly patients undergoing spinal surgery. A total of 60 patients (>65 yr old) were randomly assigned to one of two groups for maintenance of anesthesia. After the induction with 3.6 ± 1.2 mg/kg IV thiopental and endotracheal intubation facilitated with 1.4 ± 0.5 mg/kg succinylcholine, patients were maintained with either 0.5%–1.5% isoflurane, 70% N2O, and up to 7 μg/kg fentanyl (iso/fent group) or 48 ± 11 μg/kg remifentanil and 70% N2O (remi group). A mini-mental status examination was used to assess cognitive ability preoperatively, at 15, 30, and 60 min after arrival at the postanesthesia care unit and again 12–24 h postoperatively. The time from the conclusion of anesthesia to spontaneous respiration was similar in both groups. Times to eye opening (4.8 ± 2.6 vs 2.3 ± 1.1 min), extubation (6.8 ± 3.8 vs 3.2 ± 2.1 min), and verbalization (9.9 ± 6.2 vs 3.9 ± 2.6 min) were significantly shorter for the remi group (P < 0.05). Postoperative mini-mental status examination scores were significantly lower in the iso/fent group at 15 (16.3 ± 5.8 vs 23.7 ± 3.3), 30 (20.2 ± 5.2 vs 26.3 ± 2.7), and 60 min (23.5 ± 4.4 vs 27.5 ± 2.0) (P < 0.001); however, the scores equalized after 12 h. Requirements for postoperative analgesics were similar in the two groups. More patients in the remi group were treated with antiemetics (21 vs 7, P = 0.06). Use of remifentanil-N2O for maintenance did not shorten the overall length of stay in the postanesthesia care unit; a stay is often related to multiple administrative issues, rather than cognitive recovery. Implications Maintenance of anesthesia with remifentanil-nitrous oxide (N2O), compared with isoflurane-N2O-fentanyl, can safely shorten postoperative recovery of cognitive function in a geriatric population. Earlier recovery may facilitate postoperative neurological assessment. Use of remifentanil-N2O for maintenance did not shorten the overall length of stay in the postanesthesia care unit, a stay often related to multiple administrative issues, rather than cognitive recovery.