Dynamic Arterial Elastance During Experimental Endotoxic Septic Shock: A Potential Marker of Cardiovascular Efficiency

Abstract

Dynamic arterial elastance (Ea dyn ), the ratio between pulse pressure variation (PPV) and stroke volume variation (SVV), has been suggested as a dynamic parameter relating pressure and flow. We aimed to determine the effects of endotoxic septic shock and hemodynamic resuscitation on Ea dyn in an experimental study in 18 New Zealand rabbits. Animals received placebo (SHAM, n = 6) or intravenous lipopolysaccharide (E. Coli 055:B5, 1 mg⋅kg – 1 ) with or without (EDX-R, n = 6; EDX, n = 6) hemodynamic resuscitation (fluid bolus of 20 ml⋅kg – 1 and norepinephrine for restoring mean arterial pressure). Continuous arterial pressure and aortic blood flow measurements were obtained simultaneously. Cardiovascular efficiency was evaluated by the oscillatory power fraction [%Osc: oscillatory work/left ventricular (LV) total work] and the energy efficiency ratio (EER = LV total work/cardiac output). Ea dyn increased in septic animals (from 0.73 to 1.70; p = 0.012) and dropped after hemodynamic resuscitation. Ea dyn was related with the %Osc and EER [estimates: −0.101 (−0.137 to −0.064) and −9.494 (−11.964 to −7.024); p < 0.001, respectively]. So, the higher the Ea dyn, the better the cardiovascular efficiency (lower %Osc and EER). Sepsis resulted in a reduced %Osc and EER, reflecting a better cardiovascular efficiency that was tracked by Ea dyn . Ea dyn could be a potential index of cardiovascular efficiency during septic shock.

Hemodynamic effects of different fluid volumes for a fluid challenge in septic shock patients

“…Nevertheless, the AUC of 0.74 is at the marginal value to be regarded as a good predictor. This potential correlation between Ea and preload responsiveness was likely not by chance, since a recent study has explored the possibility of dynamic arterial elastance as a potential marker of cardiovascular efficiency [32] . Moreover, the previous experimental study suggested that aortic wall edema caused by sepsis could contribute to a persistent elevation in aortic characteristic impedance leading to an impaired arterial load and ventriculoarterial decoupling [33] .…”

“…This potential correlation between Ea and preload responsiveness was likely not by chance, since a recent study has explored the possibility of dynamic arterial elastance as a potential marker of cardiovascular efficiency. [32] Moreover, the previous experimental study suggested that aortic wall edema caused by sepsis could contribute to a persistent elevation in aortic characteristic impedance leading to an impaired arterial load and ventriculoarterial decoupling. [33] Whether an Ea decrease after FC indicates a better optimization of the arterial load and left ventricular workload match needs further study.…”

Unveiling the Significance of Dynamic Arterial Elastance: An Insightful Approach to Assessing Arterial Load in an Endotoxin Shock Model

“…This finding indicates that the impact of our endotoxin infusion protocol on PPV and SVV was relatively minimal. Second, EaDyn is associated with variables related to cardiac performance that we did not evaluate in the present study (22,23), and it needs to be evaluated because the changes in continuous and pulsatile components of arterial load could increase or decrease myocardial oxygen consumption. Third, we did not evaluate the Zc and inertance of the Windkessel mode.…”

“…The main differences between our study and these previous studies are the animal models used and the method of SVV measurement. In our study, we used a swine model of endotoxin shock and measured SVV using calibrated pulse contour analysis, while the other studies used a rabbit model of endotoxin shock (22), a swine model of changes in preload, afterload, and contractility (3), and a rabbit model of changes in preload and afterload (23). In addition, the SVV in our study was measured using a different method than in previous studies, which used Doppler esophageal or conductance catheter measurements.…”

“…Systemic vascular resistance and MAP represent the steady components, while Cart, Zc, and wave reflections represent the pulsatile components (19). Alterations in the steady and pulsatile components of the arterial load can decrease cardiac performance (2,22). Therefore, it is necessary to have some variable that allows characterizing the arterial load.…”