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Viscoelastic energy index and pulmonary resilience in mechanically ventilated patients: a Bayesian longitudinal
Aurio Fajardo-Campoverdi1, Adrián Gallardo2, Antuani Baptistella3
1University of La Frontera, Chile.
Objective:
The cyclical energy load imposed by the mechanical ventilator can influence mechanical efficiency and may be associated with an increased risk of lung injury. This study proposes the Viscoelastic Energy Index (VEI) and relative resilience, which incorporate biophysical, mathematical and geometric principles, to analyse the association between VEI and relative resilience with ARDS severity and ICU mortality.
Design:
International, multicentre, retrospective study; quantitative analysis of pressure-volume curves to estimate energy delivered, dissipated, and recovered per ventilatory cycle. Bayesian modelling used to assess associations and perform subgroup analyses.
Setting:
4 intensive care units across 4 Latin American countries PATIENTS: Adults who received invasive mechanical ventilation in volume-controlled mode, with (mild and moderate/severe ARDS) and without ARDS.
Main Variables Of Interest:
VEI and relative resilience, ARDS severity, ICU mortality.
Results:
High respiratory rate, elevated driving pressure and flow, lower compliance and reduced functional residual capacity were associated with lower VEI. In patients with moderate-severe ARDS, a higher VEI was associated with lower ICU mortality (posterior probability 89.6%). As VEI increased, dissipated energy rose marginally while relative resilience increased from 0.93 to 0.97, indicating improved initial mechanical efficiency. Hysteresis decreased progressively and the relative proportion of elastic and resistive components remained stable, suggesting energetic tolerance without structural overload.
Conclusions:
A higher VEI is associated with greater resilience and lower mortality in patients with ARDS. Prospective studies are needed to confirm these findings.
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