The effect of bispectral index monitoring on early cognitive functions

One hundred patients between the ages of 18-70yr, ASA physical status I-III, scheduled to undergo planed colonoscopy, will be studied. Fasting periods will be in accordance with ASA guidelines. All patients will be instructed to colonoscopy preparation is applied as a standard in the endoscopy unit. One hundred patients will be randomized, by using a computer-generated block randomisation, into 2 groups. In Group 1 (n=50), the depth of anesthesia will be monitored by the BIS (BIS Monitor, Aspect 2000TM XP, USA) and BIS scores will be maintained between 60-80. In Group 2 (n=50), BIS monitoring will not be performed. To determine the baseline levels of cognitive functions of patients, mini-mental state examination (MMSE), the Trieger dot test (TDT) and clock drawing test (CDT) will be performed on the day of the procedure after admission to the endoscopy unit. A 20-gauge IV catheter will be inserted in the right forearm when the patient arrived in the endoscopy room. Supplemental oxygen (4 l.min-1) will be administered through a nasal canul. In addition to routine monitoring (consisting of a pulse oximeter, 3-lead ECG and a non-invasive blood pressure cuff) BIS monitoring (BIS Monitor, Aspect 2000TM XP, USA) will be applied to the Group I patients. After baseline measurements (haemodynamic profiles and BIS values) will be obtained, the patient will be placed in the left lateral position. Two milligram of midazolam will be administered intravenously. Next, an initial intravenous dose of propofol (0.3–0.5 mg/kg of body weight) will be administered, followed by repeated 10–20 mg doses so as to BIS values 60-80 or the patient expressed discomfort in Group I and the the patient’s sedation level was more than MOAA/S 4 or the patient expressed discomfort in Group II. Other medications, including analgesics, will not be used in the present study. All sedation procedures will be practised by an anesthesiologis who will be blind to pre-procedure. Colonoscopy will be commenced when the anesthesiologist decided that the depth of sedation was adequate. When the patients will be classified as ready for hospital discharge according to Chung criteria (The total score is 10 and with patients scoring =>9 considered fit for discharge home), patient satisfaction will be evaluated (Dissatisfied, neutral and satisfied) and determined the post-procedural levels of cognitive functions of patients with mini-mental state examination (MMSE), the Trieger dot test (TDT) and clock drawing test (CDT). Age, gender, ASA physical status, BMI, total propofol dose, sedation time, satisfaction of patients, MOAA/S arrival to PACU will be recorded. And also heart rate (HR), mean blood pressure (MBP), oxygen saturation (SpO2) and BIS values will be recorded. We will also record any complications associated with sedation (i.e. oxygen saturation < 90 %, blood pressure < 90/50 mm Hg, heart rate < 50 bpm).