After the approve of the Ethics Committee and the patients were informed and taken informed consent form from them (18 female and 23 male) totally 41 patients between the age of 20-60 years old, who had lumbar disc hernia, under general anesthesia have been taken under the study. The patients with hepatic, renal or neurological diseases and using sedative- hypnotic, anticonvulsive and stimulant drugs and pregnant patients were excluded. Then they have been divided into two groups by closed envelope drawing method randomly and were allowed to stay hungry at least 8 hours. All the patients were applied the cognitive functions during the premedication visit MMSE (Mini Mental State Examination) that has quite practical usage and the test called Standardized Mini Mental Test Examination(SMMT-E) for the untrained persons. Test composed of question-answer in order to calculate the remembering, caution and calculation structure. All patients SMMTE scores were recorded. In the operation room, patients were applied the standard D-II derivation electrocardiography, heart beat rate, non-invasive arterial pressure, peripheral oxygen saturation (SpO2) and Bispectral Index (BİS) monitorization. Serum sale infusion was started by opening the vascular access with 18-20 gauge cannula. The skin of forehead and the temporal side were cleaned with alcohol cotton for the BİS monitorization. The electrode in the proximal part of the three electrodes of disposable BİS sensor was adhered to the middle of the forehead; the distal electrode to the temporal area on the eye line and the other electrode in between them both were adhered. The BİS values (BİS Monitor, Aspect, USA) were continuously monitored. The Group I (TİVA, n= 20) were received propofol-remifentanil and the Grup II (TİVA+D, n= 20) propofol- remifentanil and additional dexmedetomidine infusion.
Induction of propofol infusion in all two groups was started as firstly 12 mg. kg-1 for the 30 minutes, the second 30 minutes 9 mg. kg-1 and the BIS values were arranged between 40-60 until the end of the operation. At the same time remifentanil infusion 0.5 μg.kg-1 was applied as opioid and arranged according to the tension artery and heart rate. The dexmedetomidine infusion has been started as 0.5 μg.kg-1 without making the loading dose and the dose change was not made. Rocuronium 0.5 mg. kg-1 iv. was applied for the endotracheal intubation. After intubation the carbon dioxide concentration was recorded in all periods.
The patients were ventilated mechanically after the intubation in order to be ETCO2 (end-tidal carbon dioxide) 30-44 mmHg, tidal volume 8-10 mL. kg-1 . In case of tachycardia or hypertension the opioid dose was reduced in case of bradycardia or hypertension while the opioid dose was being increased. Propofol infusion was arranged to be kept in between BİS score 40-50. The effect of the used muscle relaxant was returned by neostigmine 0,05- 0,07 mg. kg-1 i.v. and atropin 0,03 mg. kg -1 i.v. After the operation all patients have been taken to the recovery room.
Then the tests of cognitive function evaluation were repeated as postoperative 2nd hour, 24 hours, 1 week and 1 month.
