Abstract
INTRODUCTION: 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 (VO(2)) response after hemodynamic interventions in cardiac surgery patients with acute circulatory instability. MATERIAL AND METHODS: 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. VO(2) responsiveness was defined as VO(2) 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. RESULTS: In the overall cohort, 24 patients (39%) were VO(2) 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 VO(2) responders (28 of 31 patients, p = 0.031). Changes in VO(2) were correlated with those of indexed total peripheral resistances, E(A), E(A)/E(V) and cardiac output. E(A)/E(V) ratio predicted VO(2) 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 VO(2) response following interventions. CONCLUSIONS: VO(2) 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 VO(2) 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.