Ventriculo-arterial uncoupling is associated with VO2dependency in cardiac surgical patients

Abstract

AbstractBackgroundThe clinical relevance of V-A (un)coupling in critically ill patients is under investigation. In this study we measured the association between V-A coupling and oxygen consumption (VO2) response in patients with acute circulatory instability following cardiac surgery.Methods and resultsSixty-one cardio-thoracic ICU patients who received fluid challenge or norepinephrine infusion were included. Arterial pressure, cardiac output (CO), heart rate (HR), arterial (EA), and ventricular elastances (EV), total indexed peripheral resistance (TPRi) were assessed before and after hemodynamic interventions. VO2responders were defined as VO2increase > 15 %. V-A coupling was evaluated by the ratio EA/EV.Left ventricle stroke work (SW) to pressure volume area (PVA) ratio was calculated. In the overall population, 24 patients (39%) were VO2responders and 48 patients were uncoupled (i.e., EA/EVratio > 1.3): 1.9 (1.6-2.4). Most of the uncoupled patients were classified as VO2responders (28 of 31 patients, p=0.031). Changes in VO2were correlated with those of TPRi, EA, EA/EVand CO. EA/EVratio predicted VO2increase with an AUC of 0.76 [95 % CI: 0.62-0.87]; p=0.001. In multivariate and principal component analyses, EA/EVand SW/PVA ratios were independently associated (P < 0.05) with VO2response following interventions.ConclusionsVO2responders were characterized by baseline V-A uncoupling due to high EAand low EV. Baseline EA/EVand SW/PVA ratios were associated with VO2changes independently of the hemodynamic intervention used. These results further underline the pathophysiological significance of V-A uncoupling in patients with hemodynamic instability.