Venous blood oxygenation measurements using TRUST and T2-TRIR during hypoxic and hypercapnic gas challenges

TRUST and T2-TRIR can be used to measure venous blood oxygenation (Yv) and oxygen extraction fraction (OEF). T2-TRIR also offers simultaneous blood T1 (T1b) measurements for hematocrit calculation in lieu of invasive blood samples. Here, TRUST and T2-TRIR were compared across a broad Yv range using hypoxic and hypercapnic challenges in healthy volunteers, while T2-TRIR-derived hematocrit estimates were compared with venipuncture results. T2-TRIR- and TRUST-derived Yv and OEF values exhibited a small constant bias (-5.4±3.5% and 6.0±4.0% respectively, both p<0.01) across all stimuli. Hematocrit by venipuncture and from T1b were unbiased but had broad confidence intervals (1.7±6.3%, p=0.20).