Ventricular arterial coupling to manage hemodynamic instability in the theatre: an elastance based approach at bedside

Abstract

Introduction: Early recognition of hemodynamic impairment using echocardiography is paramount to the optimal management of patients undergoing cardiac surgery 1. Recognising hemodynamic derangement by measuring the relationship between ventricular contractility and arterial load has been described in the critical care setting 2. We report a case of hemodynamic derangement and restoration using an elastance functional hemodynamics based approach in the operating theatre. Objectives: We investigated the accuracy and applicability of an hemodynamic approach of diagnosis and treatment based on the non-invasive measurements of left ventricular elastance (Ees), effective arterial elastance (Ea) and ventricular arterial coupling (VAC). Methods: In a patient with severe LV dysfunction undergoing emergency CABG after AMI, we applied an elastance based method. Measurements of the elastances were accomplished using a single-beat noninvasive approach 3. Conventional invasive and non invasive hemodynamic measurements (HR, BP, CI, Scv02) were also recorded. All measurements were performed at baseline (after induction of anaesthesia), and after any cardio-vasoactive treatment in order to evaluate the response. Results: Elastance measurement at baseline showed ventricular arterial uncoupling (2.42) mainly due to Ees depression (Ees 0.56 mmHg/ml, Ea 1.34 mmHg/ml). Inotrope support (Levosimendan 0.5 mcg/kg/min) was started which improved VAC (from 2.42 to 1.6) after 2 hours. Due to persistent hypotension, a vasoconstrictor was applied (Norepinephrine 0.1-0.3 mcg/kg/min) resulting in a sudden Ea rise and further decoupling (2.08). Norepinephrine was withdrawn and Esmolol 5-10 mcg/kg/ min was introduced to reduce Ea, which led to HR reduction and restored VAC (from 2.08 to 1.31) (fig.1). Conclusion: We reported the application of a functional elastance based hemodynamic approach in order to rapidly diagnose the determinants of hemodynamic alteration. In our opinion this pathophysiological method applied in the theatre, as well as already reported at bedside in the critical care setting, offers a better understanding of hemodynamic alteration and a more accurate representation of cardiac interaction with the vasculature leading to more accurate therapeutic approach. Further investigation is needed to test such approach in larger series. (Figuer Presented).