Optimization of Desflurane in Elderly Patients

Various issues had been pointed out when undergoing the anesthesia for elderly patients with sevoflurane, such as delayed emergence, post-operative trouble with swallowing. Desflurane, which has a lower blood/gas partition coefficient, is expected to contribute the better emergence, along with the recent progress on optimization of delivered amount of anesthesia. The purpose of this study is to compare the time to emergence in long elderly patient cases with desflurane or sevoflurane, with the recently developed drug-delivery optimization system "Aisys®" (GE Healthcare Japan).

The objectives of this study is to compare the time to emergence and quality of recovery in long elderly patient cases with desflurane or sevoflurane, with the recently developed drug-delivery optimization system "Aisys®" (GE Healthcare Japan). Inclusion Criteria: - Elderly patients (>= 65 yr-old), long operation (> 4hours), abdominal surgery patients Exclusion Criteria: - Liver dysfunction, Renal dysfunction, preoperative dementia Neurosurgery patients, Cardiac surgery patients, obese patients(BMI>35)

The patients in this arm will be given the general anesthesia with desflurane and be used the Aysis as the anesthetic machine.

The patients in this arm will be given the general anesthesia with sevoflurane and be used the Aysis as the anesthetic machine.

The patients in this arm will be given the general anesthesia with desflurane and be used the Aysis as the anesthetic machine.

The patients in this arm will be given the general anesthesia with sevoflurane and be used the Aysis as the anesthetic machine.

When surgery ends, the fresh gas flow rate will be increased to 6L/min (100% oxygen). Patients will be asked to open eyes by touching the shoulder, calling the name every 15 seconds. Patients will be applied stimulus every 15 seconds until following commands. Extubation will be performed when the patient is judged to be awake and spontaneous breathing recovery substantially.

When surgery ends, the fresh gas flow rate will be increased to 6L/min (100% oxygen). Patients will be asked to open eyes by touching the shoulder, calling the name every 15 seconds. Patients will be applied stimulus every 15 seconds until following commands. Extubation will be performed when the patient is judged to be awake and spontaneous breathing recovery substantially.

When surgery ends, the fresh gas flow rate will be increased to 6L/min (100% oxygen). Patients will be asked to open eyes by touching the shoulder, calling the name every 15 seconds. Patients will be applied stimulus every 15 seconds until following commands. Extubation will be performed when the patient is judged to be awake and spontaneous breathing recovery substantially.

Cognitive function will be measured by MMSE (Mini-Mental State Examination) at 24hrs pre and postoperatively. Total MMSE score is recorded by interview ranging from 0 (minimum) to 30 (maximum). MMSE score is consisted on 11 subscales, and total MMSE score is simply summation of all the subscale scores. Maximum MMSE score indicates that the patient is excellent for cognitive function. MMSE score under 26 indicated the cognitive dysfunction.

The incidence of post operative delirium will be measured by Confusion Assessment Method (CAM) at baseline, 15mins, 3hrs, 6hrs, 12hrs, 24hrs, 48hrs postoperatively.

Inclusion Criteria: - Elderly patients (>= 65 yr-old), long operation (> 4hours), abdominal surgery patients Exclusion Criteria: - Liver dysfunction, Renal dysfunction, preoperative dementia Neurosurgery patients, Cardiac surgery patients, obese patients(BMI>35)