Ventriculo-Arterial Coupling Is Associated With Oxygen Consumption and Tissue Perfusion in Acute Circulatory Failure

The determination of ventriculo-arterial coupling is gaining an increasing role in cardiovascular and sport medicine. However, its relevance in critically ill patients is still under investigation. In this study we measured the association between ventriculo-arterial coupling and oxygen consumption (VO₂) response after hemodynamic interventions in cardiac surgery patients with acute circulatory instability.

Sixty-one cardio-thoracic ICU patients (67 ± 12 years, 80% men) who received hemodynamic therapeutic interventions (fluid challenge or norepinephrine infusion) were included. Arterial pressure, cardiac output, heart rate, arterial (E_A), and ventricular elastances (E_V), total indexed peripheral resistances were assessed before and after hemodynamic interventions. VO₂ responsiveness was defined as VO₂ increase >15% following the hemodynamic intervention. Ventriculo-arterial coupling was assessed measuring the E_A/E_V ratio by echocardiography. The left ventricle stroke work to pressure volume area ratio (SW/PVA) was also calculated.

In the overall cohort, 24 patients (39%) were VO₂ responders, and 48 patients had high ventriculo-arterial (E_A/E_V) coupling ratio with a median value of 1.9 (1.6-2.4). Most of those patients were classified as VO₂ responders (28 of 31 patients, p = 0.031). Changes in VO₂ were correlated with those of indexed total peripheral resistances, E_A, E_A/E_V and cardiac output. E_A/E_V ratio predicted VO₂ increase with an AUC of 0.76 [95% CI: 0.62-0.87]; p = 0.001. In principal component analyses, E_A/E_V and SW/PVA ratios were independently associated (p < 0.05) with VO₂ response following interventions.

VO₂ responders were characterized by baseline high ventriculo-arterial coupling ratio due to high E_A and low E_V. Baseline E_A/E_V and SW/PVA ratios were associated with VO₂ changes independently of the hemodynamic intervention used. These results underline the pathophysiological significance of measuring ventriculo-arterial coupling in patients with hemodynamic instability, as a potential therapeutic target.