Subsequent and non-randomised patients, adult patients qualified for major abdominal surgeries were enrolled

Inclusion Criteria:

• scheduled for major abdominal surgery for at least 2 h
• under general anesthesia
• American Society of Anesthesiologists（ASA）physical status : II ~ III
• Age > 18

Exclusion Criteria:

• refuse of patients
• patient with results of test: "The Mini Mental State Examination"" less then 24 before operation
• neurosurgery history of patients

One hundred and one (101) subsequent and non-randomised patients, age between 35 and 84 years (mean 64±10) hospitalised at the 1st Department of General, Oncologic and Gastroenterologic Surgery of the UJ CM in Krakow, qualified for abdominal surgeries were enrolled.

1. The day before the surgery will be performed basic blood tests (morphology, gas analysis) and test "Short Scale Mental State Examination."
2. During the operation, in addition to standard monitoring the electrical activity of the heart, blood pressure and peripheral oxygen saturation levels, will be assessed non-invasively cerebral oximetry.
3. When during general anesthesia bradycardia occurs, then half of the patients in this group will be set up into the esophagus electrode, which will provide the ability to route atrial pacing hemodynamically optimal heart rate (80 / min). However, in the second half of the patients at the time of the occurrence of bradycardia is given intravenously at a dose of atropine 0.5 mg.
4. In about two hours after the surgery will be taken blood tests (morphology + gas analysis) to determine the potential impact of intraoperative bleeding changes oximetry.
5. On postoperative day 5 will be repeated test "Short Scale Mental State Examination"