Near-Infrared Spectroscopy in Adult Cardiac Surgery Patients: A Systematic Review and Meta-Analysis

Abstract

Objectives: To identify the normal baseline preoperative range of cerebral tissue oxygen saturation (SctO₂) derived using near-infrared spectroscopy (NIRS) and the efficacy of perioperative interventions designed to modulate SctO₂ in cardiac surgical patients.

Design: Systematic review and meta-analysis of relevant randomized controlled trials (RCTs) extracted from the Medline, Embase, and Cochrane Central Register of Controlled Trials databases.

Setting: Hospitals performing cardiac surgery.

Participants: The study comprised 953 participants from 11 RCTs.

Interventions: Interventions included the following: (1) SctO₂ monitoring protocol compared with no monitoring; (2) use of cardiopulmonary bypass (CPB) compared with no CPB; (3) normothermic CPB compared with hypothermic CPB; (4) glyceryl trinitrate during surgery compared with placebo; (5) midazolam during induction of anesthesia compared with propofol; (6) sevoflurane anesthesia compared with total intravenous anesthesia; (7) sevoflurane anesthesia compared with propofol-based anesthesia; and (8) norepinephrine during CPB compared with phenylephrine.

Measurements and main results: Eleven RCTs with 953 participants measured baseline preoperative SctO₂ using NIRS. The pooled mean baseline SctO₂ was 66.4% (95% CI 65.0-67.7), generating a reference range of 51.0% to 81.8%. Four interventions (1, 3, 4, and 6 described in the Interventions section above) increased intraoperative SctO₂ across the majority of reported time points. Postoperative follow-up of SctO₂ occurred in only 1 study, and postoperative cognitive assessment correlating SctO₂ with cognitive function was applied in only 4 studies using variable methodology.

Conclusions: The authors have established that reference values for baseline NIRS-derived SctO₂ in cardiac surgery patients are varied and have identified interventions that modulate SctO₂. This information opens the door to standardized research and interventional studies in this field.

Keywords: cardiac surgery; cerebral oxygenation; cerebral tissue oxygen saturation; meta-analysis; near-infrared spectroscopy; postoperative cognitive dysfunction.