Lung aeration and ventilation after percutaneous tracheotomy measured by electrical impedance tomography in non-hypoxemic critically ill patients: a prospective observational study

Abstract

BackgroundPercutaneous dilatational tracheotomy (PDT) may lead to transient impairment of pulmonary function due to suboptimal ventilation, loss of positive end-expiratory pressure (PEEP) and repetitive suction maneuvers during the procedure. Possible changes in regional lung aeration were investigated using electrical impedance tomography (EIT), an increasingly implied instrument for bedside monitoring of pulmonary aeration.MethodsWith local ethics committee approval, after obtaining written informed consent 29 patients scheduled for elective PDT under bronchoscopic control were studied during mechanical ventilation in supine position. Anesthetized patients were monitored with a 16-electrode EIT monitor for 2 min at four time points: (a) before and (b) after initiation of neuromuscular blockade (NMB), (c) after dilatational tracheostomy (PDT) and (d) after a standardized recruitment maneuver (RM) following surgery, respectively. Possible changes in lung aeration were detected by changes in end-expiratory lung impedance (Δ EELI). Global and regional ventilation was characterized by analysis of tidal impedance variation.ResultsWhile NMB had no detectable effect on EELI, PDT led to significantly reduced EELI in dorsal lung regions as compared to baseline, suggesting reduced regional aeration. This effect could be reversed by a standardized RM. Mean delta EELI from baseline (SE) was: NMB − 47 ± 62; PDT − 490 ± 180; RM − 89 ± 176, values shown as arbitrary units (a.u.). Analysis of regional tidal impedance variation, a robust measure of regional ventilation, did not show significant changes in ventilation distribution.ConclusionThough changes of EELI might suggest temporary loss of aeration in dorsal lung regions, PDT does not lead to significant changes in either regional ventilation distribution or oxygenation.

Assessment of the Effect of Recruitment Maneuver on Lung Aeration Through Imaging Analysis in Invasively Ventilated Patients: A Systematic Review

“…In two studies, there was a high concern regarding applicability of population selection. These two studies included a highly selective population, i.e., patients after cardiac surgery (Longo et al, 2017) or patients who underwent tracheostomy (Eichler et al, 2018).…”

“…Only one study addressed the prediction of response to RM in patients in the operating room. A decreasing pattern of endexpiratory lung impedance (EELI) evaluated with EIT was found to be related to the amount of re-aerated lung tissue (Eichler et al, 2018; Table 3).…”

“…Anterior located consolidations (Bouhemad et al, 2011;Tang et al, 2017) Crater-like sub-pleural consolidations (Rode et al, 2012) EIT Predominant ventilation in non-dependent areas (Zhao et al, 2019) Decreasing pattern of EELI (delta EELI >10% or EELI index <1; Eronia et al, 2017;Eichler et al, 2018) CT Not aerated tissue (>-100 HU) >25-30% of total lung tissue (Gattinoni et al, 2006;Chiumello et al, 2016) Non-focal lung morphology (Nieszkowska et al, 2004;Constantin et al, 2010) Homogeneous cephalo-caudal distribution of 40-50% non-aeration area (Caironi et al, 2010) Opening and closing lung tissue (141 ± 81 g; Caironi et al, 2010) opened, but frequently only at very high airway pressures (Cressoni et al, 2017). Borges et al found opening pressures of 60 cmH 2 O in patients with ARDS to be common, with coexistence of areas opening at lower and higher pressures in the majority of patients (Borges et al, 2006).…”

DeepEIT: Deep Image Prior Enabled Electrical Impedance Tomography

“…The spatial resolution of EIT is still limited by the intrinsic ill-posed nature. Improving EIT image resolution is critical for a variety of applications, such as lung monitoring [16], [17] and brain imaging [18]. For the past decades, various efforts † are devoted to exploiting NNs to improve EIT image quality.…”