In:
Critical Care Medicine, Ovid Technologies (Wolters Kluwer Health), Vol. 45, No. 4 ( 2017-04), p. 679-686
Kurzfassung:
Lung-protective mechanical ventilation aims to prevent alveolar collapse and overdistension, but reliable bedside methods to quantify them are lacking. We propose a quantitative descriptor of the shape of local pressure-volume curves derived from electrical impedance tomography, for computing maps that highlight the presence and location of regions of presumed tidal recruitment (i.e., elastance decrease during inflation, pressure-volume curve with upward curvature) or overdistension (i.e., elastance increase during inflation, downward curvature). Design: Secondary analysis of experimental cohort study. Setting: University research facility. Subjects: Twelve mechanically ventilated pigs. Interventions: After induction of acute respiratory distress syndrome by hydrochloric acid instillation, animals underwent a decremental positive end-expiratory pressure titration (steps of 2 cm H 2 O starting from ≥ 26 cm H 2 O). Measurements and Main Results: Electrical impedance tomography-derived maps were computed at each positive end-expiratory pressure-titration step, and whole-lung CT taken every second steps. Airway flow and pressure were recorded to compute driving pressure and elastance. Significant correlations between electrical impedance tomography-derived maps and positive end-expiratory pressure indicate that, expectedly, tidal recruitment increases in dependent regions with decreasing positive end-expiratory pressure ( p 〈 0.001) and suggest that overdistension increases both at high and low positive end-expiratory pressures in nondependent regions ( p 〈 0.027), supporting the idea of two different scenarios of overdistension occurrence. Significant correlations with CT measurements were observed: electrical impedance tomography-derived tidal recruitment with poorly aerated regions ( r = 0.43; p 〈 0.001); electrical impedance tomography-derived overdistension with nonaerated regions at lower positive end-expiratory pressures and with hyperaerated regions at higher positive end-expiratory pressures ( r ≥ 0.72; p 〈 0.003). Even for positive end-expiratory pressure levels minimizing global elastance and driving pressure, electrical impedance tomography-derived maps showed nonnegligible regions of presumed overdistension and tidal recruitment. Conclusions: Electrical impedance tomography-derived maps of pressure-volume curve shapes allow to detect regions in which elastance changes during inflation. This could promote individualized mechanical ventilation by minimizing the probability of local tidal recruitment and/or overdistension. Electrical impedance tomography-derived maps might become clinically feasible and relevant, being simpler than currently available alternative approaches.
Materialart:
Online-Ressource
ISSN:
0090-3493
DOI:
10.1097/CCM.0000000000002233
Sprache:
Englisch
Verlag:
Ovid Technologies (Wolters Kluwer Health)
Publikationsdatum:
2017
ZDB Id:
2034247-0
