The Association of the Systemic Oxygen Delivery to Oxygen Consumption Ratio With Mortality, Heart Transplantation, and Mechanical Circulatory Support.

OBJECTIVES

To identify if the delivery of oxygen over consumption of oxygen (DO2/VO2) ratio is significantly associated with clinical outcomes such as mortality, need for heart transplantation, or need for a mechanical circulatory support device.

DESIGN

Retrospective cohort study.

SETTING

Medical and surgical cardiac intensive care units of the Mayo Clinic.

PARTICIPANTS

Adult patients (≥18 years old) admitted to the cardiothoracic surgical or cardiac intensive care units between January 2012 and December 2025 were included if they underwent invasive hemodynamic assessment with simultaneous arterial blood gas, mixed venous blood gas, hemoglobin, and mean arterial pressure. Patients were excluded if they had their venous oxygen saturations drawn from a central line or a peripherally inserted central catheter, as well as those admitted for sepsis/septic shock.

INTERVENTIONS: No interventions were performed on patients.

MEASUREMENTS AND MAIN

RESULTS

DO2/VO2 demonstrated a nonlinear association with mortality. Using the median value of 4.73 as a reference point, patients with a DO2/VO2 value of ∼2 had the highest likelihood of mortality. Kaplan-Meier analysis using a prespecified cut-point of 5 did not demonstrate any significant relationship with mortality, likely because of the underlying nonlinear relationship. There was no significant association between DO2/VO2 ratio and the need for mechanical circulatory support or heart transplantation.

CONCLUSIONS

DO₂/VO₂ is a marker of systemic oxygen balance that complements conventional hemodynamic indices. A categorical threshold of 5 did not show an association with clinical outcomes, but continuous analyses did suggest that a low DO₂/VO₂ may identify a high-risk phenotype.