Validation of a Novel Method for Noninvasive Mixed Venous Oxygen Saturation Monitoring in Anesthetized Children

Mixed venous oxygen saturation (SvO 2 ) is a critical variable in the assessment of oxygen supply and demand but is rarely used in children due to the invasive nature of pulmonary artery catheters. The aim of this prospective, observational study was to investigate the accuracy of noninvasively measured SvO 2 acquired by the novel capnodynamic method, based on differential Fick equation (Capno-SvO 2 ), against gold standard CO-oximetry.

Capno-SvO 2 was compared to SvO 2 measured by pulmonary artery blood gas CO-oximetry in children undergoing cardiac catheter interventions and subjected to moderate hemodynamic challenges. Bland-Altman analysis was used to describe the agreement of absolute values between CO-oximetry and Capno-SvO 2 , and a concordance rate was calculated to evaluate the ability of Capno-SvO 2 to track change.

Twenty-five procedures were included in the study. Capno-SvO 2 showed a bias toward CO-oximetry of +3 percentage points; upper and lower limits of agreement were +11 percentage points (95% confidence interval [CI], 9-14) and -5 percentage points (95% CI, -8 to -3), respectively. The concordance rate was 92% (95% CI, 89-96).

In conclusion, this first clinical application of a novel concept for noninvasive SvO 2 monitoring without the need for a pulmonary artery catheter indicates that Capno-SvO 2 generates absolute values and trending capacity in close agreement with the gold standard reference method.