Novel noninvasive estimation of mixed venous oxygen saturation by echocardiography and expired gas analysis

Clinical use of mixed venous oxygen saturation ([Formula: see text]) is limited for the required invasive procedure. With Fick’s equation, expired gas analysis, echocardiography, simple blood tests, and percutaneous oxygen saturation, [Formula: see text] can be calculated noninvasively. We hypothesized that noninvasively calculated [Formula: see text] shows a significant correlation and agrees well with invasively measured [Formula: see text]. The present study examined the relationship between measured [Formula: see text] and calculated [Formula: see text] in patients who underwent right heart catheterization and demonstrated acceptable agreement. This novel method can expand the indication of evaluating [Formula: see text].

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Ratio of Mixed Venous Oxygen Saturation-to-Pulmonary Capillary Wedge Pressure: Insights From the Veterans Affairs Clinical Assessment, Reporting, and Tracking Program

Circulation Heart Failure ◽

10.1161/circheartfailure.121.008838 ◽

2022 ◽

Author(s):

Dustin Hillerson ◽

Richard Charnigo ◽

Sun Moon Kim ◽

Amrita Iyengar ◽

Matthew Lane ◽

...

Keyword(s):

Oxygen Saturation ◽

Pulmonary Capillary Wedge Pressure ◽

Right Heart Catheterization ◽

Mixed Venous Oxygen Saturation ◽

Heart Catheterization ◽

Right Heart ◽

Pulmonary Capillary ◽

Venous Oxygen Saturation ◽

Wedge Pressure ◽

Mixed Venous

Background: Hemodynamic values from right heart catheterization aid diagnosis and clinical decision-making but may not predict outcomes. Mixed venous oxygen saturation percentage and pulmonary capillary wedge pressure relate to cardiac output and congestion, respectively. We theorized that a novel, simple ratio of these measurements could estimate cardiovascular prognosis. Methods: We queried Veterans Affairs’ databases for clinical, hemodynamic, and outcome data. Using the index right heart catheterization between 2010 and 2016, we calculated the ratio of mixed venous oxygen saturation-to-pulmonary capillary wedge pressure, termed ratio of saturation-to-wedge (RSW). The primary outcome was time to all-cause mortality; secondary outcome was 1-year urgent heart failure presentation. Patients were stratified into quartiles of RSW, Fick cardiac index (CI), thermodilution CI, and pulmonary capillary wedge pressure alone. Kaplan-Meier curves and Cox proportional hazards models related comparators with outcomes. Results: Of 12 019 patients meeting inclusion criteria, 9826 had values to calculate RSW (median 4.00, interquartile range, 2.67–6.05). Kaplan-Meier curves showed early, sustained separation by RSW strata. Cox modeling estimated that increasing RSW by 50% decreases mortality hazard by 19% (estimated hazard ratio, 0.81 [95% CI, 0.79–0.83], P <0.001) and secondary outcome hazard by 28% (hazard ratio, 0.72 [95% CI, 0.70–0.74], P <0.001). Among the 3793 patients with data for all comparators, Cox models showed RSW best associated with outcomes (by both C statistics and Bayes factors). Furthermore, pulmonary capillary wedge pressure was superior to thermodilution CI and Fick CI. Multivariable adjustment attenuated without eliminating the association of RSW with outcomes. Conclusions: In a large national database, RSW was superior to conventional right heart catheterization indices at assessing risk of mortality and urgent heart failure presentation. This simple calculation with routine data may contribute to clinical decision-making in this population.

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