Differentiating Phenotypes of Coronavirus Disease-2019 Pneumonia by Electric Impedance Tomography

Abstract

Introduction: Coronavirus disease-2019 (COVID-19) pneumonia has different phenotypes. Selecting the patient individualized and optimal respirator settings for the ventilated patient is a challenging process. Electric impedance tomography (EIT) is a real-time, radiation-free functional imaging technique that can aid clinicians in differentiating the "low" (L-) and "high" (H-) phenotypes of COVID-19 pneumonia described previously.

Methods: Two patients ("A" and "B") underwent a stepwise positive end-expiratory pressure (PEEP) recruitment by 3 cmH2O of steps from PEEP 10 to 25 and back to 10 cmH2O during a pressure control ventilation of 15 cmH2O. Recruitment maneuvers were performed under continuous EIT recording on a daily basis until patients required controlled ventilation mode.

Results: Patients "A" and "B" had a 7- and 12-day long trial, respectively. At the daily baseline, patient "A" had significantly higher compliance: mean ± SD = 53 ± 7 vs. 38 ± 5 ml/cmH2O (p < 0.001) and a significantly higher physiological dead space according to the Bohr-Enghoff equation than patient "B": mean ± SD = 52 ± 4 vs. 45 ± 6% (p = 0.018). Following recruitment maneuvers, patient "A" had a significantly higher cumulative collapse ratio detected by EIT than patient "B": mean ± SD = 0.40 ± 0.08 vs. 0.29 ± 0.08 (p = 0.007). In patient "A," there was a significant linear regression between the cumulative collapse ratios at the end of the recruitment maneuvers (R 2 = 0.824, p = 0.005) by moving forward in days, while not for patient "B" (R 2 = 0.329, p = 0.5).

Conclusion: Patient "B" was recognized as H-phenotype with high elastance, low compliance, higher recruitability, and low ventilation-to-perfusion ratio; meanwhile patient "A" was identified as the L-phenotype with low elastance, high compliance, and lower recruitability. Observation by EIT was not just able to differentiate the two phenotypes, but it also could follow the transition from L- to H-type within patient "A."

Clinical trial registration: www.ClinicalTrials.gov, identifier: NCT04360837.

Keywords: Coronavirus-COVID-19; acute lung injury; compliance; electric impedance tomography; recruitment maneuver.

Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2022 Lovas, Chen, Molnár, Benyó, Szlávecz, Hawchar, Krüger-Ziolek and Möller.

Figures

Figure 1

Computed tomography (CT) scans of patients (A) and (B). (A) Multifocal, subpleural, bilateral ground glass opacities with subpleural traction in the dorsal regions. (B) Multifocal, subpleural, bilateral ground glass opacities, crazy paving dominantly on the left side, consolidation in the right basal region.

Figure 2

Compliance at baseline and following positive end-expiratory pressure (PEEP) trial. Cstat, compliance. Solid line, significant difference within a patient. Dashed line, significant difference between patients. Box plots represent mean, ± SD and 5th-95th percentile, p < 0.05.

Figure 3

(A,B) Alteration in compliance by moving forward in days. Cstat, compliance. Bars represent mean and ± SD. *significant difference as compared to day 1, p < 0.05.

Figure 4

(A,B) Cumulative collapse ratio following PEEP trial.

Figure 5

Pixel overdistension and collapse images on each day with patients (A,B) at top PEEP 25 and final PEEP 10 cmH2O and optimal PEEP levels. PEEP, positive end-expiratory pressure.