Predictors of Pneumothorax/Pneumomediastinum in Mechanically Ventilated COVID-19 Patients

Abstract

Objective: To determine the incidence, predictors, and outcome of pneumothorax (PNX)/pneumomediastinum (PMD) in coronavirus disease 2019 (COVID-19) acute respiratory distress syndrome (ARDS).

Design: Observational study.

Setting: Tertiary-care university hospital.

Participants: One hundred sixteen consecutive critically ill, invasively ventilated patients with COVID-19 ARDS.

Interventions: The authors collected demographic, mechanical ventilation, imaging, laboratory, and outcome data. Primary outcome was the incidence of PNX/PMD. Multiple logistic regression analyses were performed to identify predictors of PNX/PMD.

Measurements and main results: PNX/PMD occurred in a total of 28 patients (24.1%), with 22 patients developing PNX (19.0%) and 13 developing PMD (11.2%). Mean time to development of PNX/PMD was 14 ± 11 days from intubation. The authors found no significant difference in mechanical ventilation parameters between patients who developed PNX/PMD and those who did not. Mechanical ventilation parameters were within recommended limits for protective ventilation in both groups. Ninety-five percent of patients with PNX/PMD had the Macklin effect (linear collections of air contiguous to the bronchovascular sheaths) on a baseline computed tomography scan, and tended to have a higher lung involvement at intensive care unit (ICU) admission (Radiographic Assessment of Lung Edema score 32.2 ± 13.4 v 18.7 ± 9.8 in patients without PNX/PMD, p = 0.08). Time from symptom onset to intubation and time from total bilirubin on day two after ICU admission were the only independent predictors of PNX/PMD. Mortality was 60.7% in patients who developed PNX/PMD versus 38.6% in those who did not (p = 0.04).

Conclusion: PNX/PMD occurs frequently in COVID-19 patients with ARDS requiring mechanical ventilation, and is associated with increased mortality. Development of PNX/PMD seems to occur despite use of protective mechanical ventilation and has a radiologic predictor sign.

Keywords: COVID-19; Macklin effect; SARS-CoV-2; acute respiratory distress syndrome; barotrauma; mechanical ventilation; pneumothorax.

Fig 1

Study flow chart with radiologic findings. Abbreviations: ARDS, acute respiratory distress syndrome; COVID-19, coronavirus disease 2019; CT, computed tomography; ICU, intensive care unit; IMV, invasive mechanical ventilation; PNX/PMD, pneumothorax/pneumomediastinum.

Fig 2

Lung parenchyma window axial computed tomography scans of 3 patients with severe acute respiratory syndrome coronavirus 2-associated pneumonia presenting Macklin effect (arrows) in association with pneumothorax (A), early pneumomediastinum (B), and full-blown pneumomediastinum along with subcutaneous emphysema (C).