OBJECTIVES: Near-infrared spectroscopy (NIRS) is used in critical care settings to measure regional cerebral tissue oxygenation (rSo2). However, the accuracy of such measurements has been questioned in darker-skinned individuals due to the confounding effects of light absorption by melanin. In this systematic review, we aim to synthesize the available evidence on the effect of skin pigmentation on rSo2 readings. DATA SOURCES: We systematically searched MEDLINE, Cochrane Database of Systematic Reviews, Embase, and Google Scholar from inception to July 1, 2023. STUDY SELECTION: In compliance with our PROSPERO registration (CRD42022347548), we selected articles comparing rSo2 measurements in adults either between racial groups or at different levels of skin pigmentation. Two independent reviewers conducted full-text reviews of all potentially relevant articles. DATA EXTRACTION: We extracted data on self-reported race or level of skin pigmentation and mean rSo2 values. DATA SYNTHESIS: Of the 11,495 unique records screened, two studies (n = 7,549) met our inclusion criteria for systematic review. Sun et al (2015) yielded significantly lower rSo2 values for African Americans compared with Caucasians, whereas Stannard et al (2021) found little difference between self-reported racial groups. This discrepancy is likely because Stannard et al (2021) used a NIRS platform which specifically purports to control for the effects of melanin. Several other studies that did not meet our inclusion criteria corroborated the notion that skin pigmentation results in lower rSo2 readings. CONCLUSIONS: Skin pigmentation likely results in attenuated rSo2 readings. However, the magnitude of this effect may depend on the specific NIRS platform used.
