Prone Positioning Decreases Inhomogeneity and Improves Dorsal Compliance in Invasively Ventilated Spontaneously Breathing COVID-19 Patients—A Study Using Electrical Impedance Tomography

Abstract

Background: We studied prone positioning effects on lung aeration in spontaneously breathing invasively ventilated patients with coronavirus disease 2019 (COVID-19). Methods: changes in lung aeration were studied prospectively by electrical impedance tomography (EIT) from before to after placing the patient prone, and back to supine. Mixed effect models with a random intercept and only fixed effects were used to evaluate changes in lung aeration. Results: fifteen spontaneously breathing invasively ventilated patients were enrolled, and remained prone for a median of 19 [17 to 21] hours. At 16 h the global inhomogeneity index was lower. At 2 h, there were neither changes in dorsal nor in ventral compliance; after 16 h, only dorsal compliance (βFe +18.9 [95% Confidence interval (CI): 9.1 to 28.8]) and dorsal end-expiratory lung impedance (EELI) were increased (βFe, +252 [95% CI: 13 to 496]); at 2 and 16 h, dorsal silent spaces was unchanged (βFe, –4.6 [95% CI: –12.3 to +3.2]). The observed changes induced by prone positioning disappeared after turning patients back to supine. Conclusions: in this cohort of spontaneously breathing invasively ventilated COVID-19 patients, prone positioning decreased inhomogeneity, increased lung volumes, and improved dorsal compliance.

Prone Positioning for Patients With COVID-19–Induced Acute Hypoxemic Respiratory Failure: Flipping the Script

“…Moreover, the variability of tidal impedance can be affected by body position and respiratory efforts. 60 To date, 7 prospective studies 22,59,[61][62][63][64][65] on 10À25 intubated subjects with COVID-19 have investigated lung aeration and ventilation during PP, assessed by EIT and/or CT (Table 2). Unlike APP for non-intubated subjects, intubated subjects in most studies were found to have significant increase of lung aeration in dorsal regions and decreased aeration in ventral regions, as shown in Table 2 and Figure 2.…”

“…Pierrakos et al 65 assessed the change in ventilation using EIT in 15 subjects with COVID-19 who underwent PP for a median of 19 h. Notably, this is the only study where subjects had spontaneous breathing activity. The authors reported a significant improvement of aeration in dorsal regions and a non-significant decrease in the incidence of pendelluft phenomenon from 46% to 35%.…”

“…The authors reported a significant improvement of aeration in dorsal regions and a non-significant decrease in the incidence of pendelluft phenomenon from 46% to 35%. 65 Ventilation/perfusion match. Despite the mechanisms of alveolar recruitment shown in the aforementioned studies, it should be recognized that the potential for lung recruitment varied widely among individuals.…”