The utility of near infrared spectroscopy for estimating the mixed venous saturation in children: insights using data from extracorporeal membrane oxygenation

Background: As near infrared spectroscopy (NIRS) offers a noninvasive means by which to monitor regional venous saturation, this study set forth to determine the correlation between near infrared spectroscopy values and mixed venous saturations (SvO2) obtained while on veno-arterial extracorporeal membrane oxygenation (VA-ECMO). Methods: This was a single-center retrospective study which included pediatric patients who required VA-ECMO and had cerebral and renal NIRS values between November 2020 through November 2021. Demographic data, SvO2, and cerebral and renal NIRS were collected in all patients. A Bayesian linear regression was done to model the SvO2 using the NIRS values. A venous saturation estimate was calculated by averaging the NIRS values. A Bland-Altman analysis and a Bayesian Pearson correlation coefficient calculation were performed between the actual SvO2 and both the modeled and the average-estimated SvO2. Results: Data from a total of nine patients were used in the final analyses. Bayesian linear regression analyses demonstrated that both cerebral and renal NIRS values were statistically significantly associated with the measured SvO2. The mean difference between the estimated and measured SvO2 was -19 (-34 to -5). The Bayesian Pearson correlation coefficient was 0.574 (0.492 to 0.642). When the SvO2 was estimated with a simple average of the cerebral and renal NIRS values, the mean difference between the average estimated and measured SvO2 was 2 (-14 to 18). The Pearson correlation coefficient was 0.530 (0.443 to 0.604). Conclusion: Regional NIRS can be used to estimate SvO2 in critically ill children with moderate correlation in patients in VA-ECMO.