The correlation of non-invasive hemoglobin testing and lab hemoglobin in surgical patients: A systematic review and meta-analysis

Background The decision regarding intraoperative transfusion has traditionally been based on hemodynamic instability and estimated blood loss. We performed a systematic review to determine the validity of the oximetry method compared to standard of care for hemoglobin measurement.Methods A systematic literature review was conducted, and several libraries were searched from inception to March 31,2023. The primary outcome was comparing the mean difference between laboratory-derived hemoglobin and non-invasive, point-of-care hemoglobin measurement. Subgroup analysis included comparing the mean difference in the pediatric population and among female patients.Results A total of 276 studies were identified, and 37 were included. We found that the pooled mean difference varied qualitatively between adult and pediatric population (p value for heterogeneity <0.001). In adult populations, lab hemoglobin measurements were on average slightly higher than non-invasive measurements (mean difference = 0.23; 95% CI -0.13, 0.59), though there was greater heterogeneity across studies (I2 = 97%, p value = <0.001). In the pediatric population, most studies showed lab hemoglobin to be slightly lower (mean difference = -0.42; 95% CI -0.87 to 0.03).Conclusions In general, there was no clinically significant difference in mean hemoglobin among adult and pediatric populations. The percentage of female participants had no effect on the mean difference in hemoglobin.