Intraoperative hyperoxygenation may negatively affect postoperative cognitive functions in coronary artery bypass graft operations: A randomized controlled study.

Abstract

In this study, it was aimed to compare various parameters during surgery and postoperative cognitive functions in patients undergoing coronary artery bypass graft (CABG) surgery using different levels of perioperative oxygen. One hundred patients scheduled for elective CABG surgery were included in the study. The patients were divided into two groups according to arterial oxygen levels during surgery. In the normoxia group (NG) (n = 50), partial arterial oxygen pressure(PaO2 ) was between ≥100and <180 mmHg with at least 40% fraction of inspired oxygen (FiO2 ) mechanical ventilation (MV), and in the hyperoxia group (HG) (n = 50), PaO2 was ≥180 mmHg with 100% FiO2 MV. Hemodynamic parameters, peripheral oxygen saturation (SpO2 ), regionalcerebral oxygen saturation (rSO2 ) measured from bilateral sensors, and blood gas values were recorded at the planned measurement times. Postoperative features (mortality and infection rates, length of stay in the hospital, and intensive care unit) and complications of the patients have been recorded (low cardiac output syndrome, renal failure, delirium). Mini-Mental State Examination (MMSE) testwas applied to the patients before and at the 12th, 24th hours; on the first, third, sixth months after surgery. Extubation time was found to be shorter in NG (p < .05). Between the groups, rSO2 and mean arterial pressurewere found to be significantly lower in HG at the time of T4 measurement (p = .042, p = .038, respectively). MMSE values of the groups at the first, third, and sixth months were found to be significantly higher in NG (p = .017, p = .014, p = .002, respectively). Hyperoxemia application during CABG may be associated with worse postoperative late-term cognitive functions.