Background Adverse neurocognitive and functional outcomes are common after cardiac surgery. Cerebral near-infrared spectroscopy (NIRS) monitors regional cerebral oxygen saturation, allowing clinicians to detect and reverse cerebral desaturation. We conducted a systematic review and meta-analysis of randomised controlled trials (RCTs) to evaluate whether intraoperative NIRS monitoring improves neurocognitive outcomes after cardiac surgery. Methods We searched CENTRAL, CINAHL, EMBASE, MEDLINE, PsycINFO, and Web of Science for RCTs comparing NIRS-guided intraoperative management with usual care in adults undergoing on-pump cardiac surgery on the outcomes of postoperative cognitive decline, delirium, stroke, mortality, and functional recovery. We pooled data using random-effects meta-analysis and assessed certainty of evidence using GRADE methodology. Results We included seventeen RCTs (n = 2,288). NIRS-guided management probably reduces early POCD (RR 0.65, 95% CI 0.42–0.99; I2 = 65%; moderate-certainty), probably has little or no effect on stroke (RR 0.89, 95% CI 0.42–1.91; low-certainty) or mortality (RR 0.84, 95% CI 0.47–1.52; low-certainty), and may have no effect on delirium (RR 0.78, 95% CI 0.56–1.09; I2 = 32%; low certainty). Findings were primarily derived from small, single-centre trials with heterogenous NIRS thresholds and intervention algorithms. Few studies evaluated outcomes beyond 30 days, and none evaluated validated measures of quality-of-life or function. Conclusions Although NIRS-guided intraoperative care shows promise for reducing early POCD after cardiac surgery, evidence of benefit for other neurocognitive or clinical outcomes remains limited. Large multi-centre studies are needed to confirm its utility, refine intervention thresholds, and determine its impact on long-term cognition, function and quality-of-life. Registration The protocol for this systematic review was pre-registered with PROSPERO International Prospective Register of Systematic Reviews (CRD42022336468).
