Ea/Ees and oscillatory power fraction capture complementary but distinct components of ventriculoarterial coupling: a porcine study.

Introduction: Ventriculoarterial coupling (VAC), traditionally assessed using the invasive "gold standard" Ea/Ees ratio (arterial elastance to end-systolic elastance), is clinically important but requires approximations that are impractical at the bedside. Oscillatory power fraction (OPF), defined as the ratio of oscillatory to total hydraulic power and derived from synchronized aortic flow-pressure measurements, has been proposed as a pragmatic VAC surrogate. This study aimed to clarify the possible correlation between VAC and OPF in pharmacologically induced hemodynamic extremes. Methods: In 14 juvenile pigs challenged with vasoactive (phenylephrine, nitroprusside) and cardioactive drugs (dobutamine, esmolol) titrated toward protocolized targets (± 40% MAP, ± 50% d Results: Ea/Ees changed by 10%-36% across the four interventions, whereas OPF changed by 1.5%-12%, and under phenylephrine and dobutamine, the change in OPF was negligible (| Conclusion: Ea/Ees and OPF are not interchangeable. OPF responded far less strongly than Ea/Ees to the loading changes imposed here and did not resolve them under two of the four challenges. This is consistent with the two indices reflecting predominantly steady and pulsatile aspects of arterial load, although the present data do not demonstrate that separation directly. While OPF cannot replace Ea/Ees, power-derived indices offer practical adjuncts for characterizing ventriculoarterial interactions and the effects of selected drugs at the intensive care bedside.