Brain Oxygen Supply in Older Adults During Coronary Artery Bypass Grafting

Abstract

Objectives: To evaluate the dynamics of the cerebral oxygen supply in patients aged ≥65 years, during coronary artery bypass grafting (CABG), and to test the hypothesis that lower intraoperative brain oxygen saturation is associated with postoperative neurological complications.

Design: Prospective cohort study.

Setting: The E. Meshalkin National Medical Research Center of the Ministry of Health of the Russian Federation, Novosibirsk, Russia.

Participants: The study comprised 200 elderly patients who underwent CABG between April, 2018 and November, 2019.

Interventions: None.

Measurements and main results: The regional hemoglobin oxygen saturation (rSO₂, %) of the right and left brain hemispheres were assessed during the intraoperative period using bilateral near-infrared spectroscopy. Furthermore, neurological complications during hospitalization were evaluated. At the anesthesia induction stage, the average levels of rSO₂ for the right and left hemispheres were within 65% and did not differ significantly at any stage of CABG (p>0.05). The risk of neurological complications was associated with rSO₂ decrease during cardiopulmonary bypass (CPB). An increased risk was associated with rSO₂ decrease by 20% or more during CPB, relative to the stage of anesthesia induction, which was observed in 19% of patients.

Conclusions: In elderly patients, the decrease in rSO₂ during CPB is associated with an increased risk of neurological complications during hospitalization. This risk increases with a decrease in rSO₂ by 20% or more during CPB relative to the stage of anesthesia induction, by a 5-fold and 7-fold for the left and right hemispheres, respectively.

Keywords: cerebral oxygen saturation; coronary artery bypass grafting; elderly patients; neurological complications.