Electric impedance tomography to predict weaning and extubation failure

Abstract

Introduction: Early assessment of weaning failure and prediction of extubation failure are crucial for management of invasively ventilated patients.

Aim: Evaluating whether changes in end-expiratory lung impedance (dEELI) and tidal impedance variation (TIV) by electrical impedance tomography (EIT) may predict weaning failure early in the course of the spontaneous breathing trial (SBT) and extubation failure soon after tube removal.

Methods: Multicentre study planning enrolment of 80 invasively ventilated ICU patients. dEELI and TIV are computed averaging 5 consecutive minutes during mechanical ventilation (baseline), at SBT initiation (SBT_0) and end (SBT_30), immediately (SB_0) and 30 minutes after extubation (SB_30). Data comparisons are made between subgroups stratified for weaning and extubation outcome.

Results: So far, we enrolled 46 patients. Compared to baseline, patients (n=11) failing SBT, as opposed to those succeeding, show dEELI significantly more negative at SBT_0 (-281 [-1048; -119] vs. -126 [-241; 18] ml, p=0.015) and SBT_30 (-279 [-1396; -156] vs. -73 [-247; 116] ml, p=0.008). No significant loss of dEELI (p= 0.172 at SB_30) was observed in the patients who failed extubation(n=14), compared to those who succeeded (n=21). TIV was no significantly different in any comparisons.

Conclusions: While changes in TIV are unhelpful for assessing the risk of both weaning and extubation failure, early fall of dEELI occurs in patients failing SBT, as opposed to those succeeding. The values of dEELI are not significantly different between the patients failing extubation and those succeeding, despite a trend toward a greater reduction in the formers, which makes necessary achieving the planned sample size.