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Endotoxin Activity Assay for the Detection of Whole Blood Endotoxemia in Critically Ill Patients
Published on: June 24, 2019
Loading conditions rather than contractility primarily determine biventricular ejection fraction in endotoxic shock
Manuel Ignacio Monge García1, Brennan Schneider2, George Ma2
1M. Ignacio Monge García: Critical Care and Emergency Department, Hospital Universitario de Puerto Real, Puerto Real, Spain.
Summary
Ejection fraction (EF) in sepsis is load-dependent. Hemodynamic factors like arterial elastance and volume, not contractility, primarily determine left ventricular EF in endotoxic shock.
Area of Science:
- Cardiovascular Physiology
- Critical Care Medicine
- Hemodynamics
Background:
- Ejection fraction (EF) is a standard metric for cardiac function assessment in sepsis.
- However, EF is significantly influenced by loading conditions, potentially masking intrinsic myocardial contractility.
- Understanding the determinants of EF in sepsis is crucial for accurate cardiac assessment.
Purpose of the Study:
- To quantify the contribution of various hemodynamic determinants to left ventricular EF (LVEF) and right ventricular EF (RVEF) in a porcine model of endotoxic shock.
- To investigate whether loading conditions or intrinsic contractility are the primary drivers of EF during sepsis.
Main Methods:
- A porcine model of endotoxic shock was utilized, with animals instrumented with biventricular conductance catheters.
- Hemodynamic parameters including effective arterial elastance (Ea), end-systolic elastance (Ees), end-diastolic volume (EDV), and heart rate (HR) were measured across four stages: baseline, shock, resuscitation, and norepinephrine infusion.
- Centering within clusters linear mixed models were employed to determine the relative importance of six candidate determinants on LVEF and RVEF.
Main Results:
- For LVEF, effective arterial elastance (Ea), end-diastolic volume (EDV), and end-systolic elastance (Ees) were the dominant determinants, explaining 77% of the variance.
- Heart rate (HR) negatively impacted LVEF, while it positively affected RVEF.
- Loading conditions (Ea, EDV) were identified as primary determinants of LVEF, overriding intrinsic contractility (Ees) in this endotoxic shock model.
Conclusions:
- In endotoxic shock, hemodynamic loading conditions, specifically arterial elastance and ventricular volumes, are the principal determinants of LVEF, not intrinsic contractility.
- The findings highlight the load-dependent nature of EF, emphasizing the need for careful interpretation in septic states.
- Similar determinant hierarchies were observed for RVEF, albeit with distinct profiles and greater uncertainty.
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