Retinal oxygen saturation as a non‐invasive estimate for mixed venous oxygen saturation and cardiac output

AbstractPurposeTo investigate the correlation between retinal vessel oxygen saturation and mixed venous oxygen saturation (SvO2‐mixed) and cardiac output (CO).MethodsRetinal arterial (SaO2‐retinal) and venous (SvO2‐retinal) oxygen saturation were measured non‐invasively with dual‐wavelength retinal oximetry in subjects receiving invasive measurements of SvO2‐mixed and CO through right heart catheterization. Correlations were analysed using Spearman's rank correlation coefficients and linear regression models.ResultsFourteen patients (median age 62.7 years, range: 21–77) were included in the analysis. When adjusted for age, SvO2‐retinal showed a positive correlation with SvO2‐mixed (β = 0.80, p = 0.003). Retinal arteriovenous oxygen saturation difference was significantly correlated with the inverse of CO (Spearman's ρ = 0.59, p = 0.026).ConclusionThis pilot study provides proof of concept for the use of retinal oximetry as a non‐invasive tool to assess systemic cardiovascular function.