Abstract
Dynamic arterial elastance (Eadyn), 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 Eadyn 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). Eadyn increased in septic animals (from 0.73 to 1.70; p = 0.012) and dropped after hemodynamic resuscitation. Eadyn 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 Eadyn, 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 Eadyn. Eadyn could be a potential index of cardiovascular efficiency during septic shock.
Highlights
Variations in left ventricular (LV), stroke volume (SV), and arterial pulse pressure (PP) are closely related to changes in intrathoracic pressure during respiration (Pinsky, 1997)
The infusion of LPS resulted in a hyperdynamic hemodynamic profile with a progressive increase in Cardiac output (CO) secondary to a positive chronotropic response, a significant reduction in mean arterial pressure (35%), and a decreased arterial load (Table 1)
All experimental groups showed a significant decrease in the evolution of arterial load, the group and time interaction analysis showed that the changes in C and characteristic impedance (Zc) were more pronounced in the endotoxic group without hemodynamic resuscitation (EDX)
Summary
Variations in left ventricular (LV), stroke volume (SV), and arterial pulse pressure (PP) are closely related to changes in intrathoracic pressure during respiration (Pinsky, 1997). The magnitude of these changes has been used to define preloaddependency (Pinsky, 2012). Since the change in arterial PP for a change in SV has the dimension of elastance, the ratio between the PP variation (PPV) and SV variation (SVV) has been described as dynamic arterial elastance (Eadyn) This parameter has been proposed as a functional measure of the arterial load (Monge Garcia et al, 2014). Eadyn could be considered as a composite index reflecting the interaction between both arterial and cardiac factors and potentially providing valuable information regarding cardiovascular performance and ventriculo-arterial coupling
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