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

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.