(1151) Pneumomediastinum in COVID-19 Pneumonia: A Result of Frequent Imaging, Not Ventilator Barotrauma?

Introduction: Incidental pneumomediastinum (PM) is classically considered to be relatively benign. In the setting of infection with the SARS-CoV-2 coronavirus, PM has been suggested to be caused by aggressive ventilator settings and is associated with increased mortality. PM is diagnosed by radiographic exams including chest x-ray and computed tomography of the chest. The goal of this study was to evaluate whether the increased rate of PM in COVID-19 patients is a result of frequent imaging rather than high ventilator settings.

Methods: This study was a single-institution retrospective review of patients hospitalized with COVID-19 requiring mechanical ventilation from January 1, 2020, to June 30, 2022. Patients with a diagnosis of PM were identified and matched to non-PM patients within this cohort by age, sex, and Charleson Comorbidity Index. Data collected for these patients included demographics, radiologic studies, and clinical outcomes. Mortality, ventilator exposure and settings, and frequency of thoracic imaging were compared between groups. Categorical variables were compared using Chi-squared tests or Fishers exact tests. Continuous variables were compared using t-tests or Wilcoxon rank sum tests depending on distribution.

Results: A total of 456 patient charts were reviewed. Fifty patients were noted to have PM (11%). There was no difference in intubation length or positive end-expiratory pressure (PEEP) settings between groups. Patients with PM underwent thoracic imaging during admission than patients without PM (0.90 vs 0.41 images per patient day, p<.0001). Focusing on the imaging performed prior to PM diagnosis, patients with PM had a significantly higher frequency of imaging at 0.85 images per patient day (p <.0001). Patients with PM had increased 30-day mortality (58% vs 32%, p=.0092).

Conclusions: A more severely ill group of COVID-19 patients, as evidenced by significantly higher mortality, is diagnosed with PM. Duration of ventilation and PEEP settings were not higher in patients with PM, but these patients did undergo significantly more imaging prior to diagnosis and throughout admission. The findings presented here suggest that the detection of PM may be an artifact of increased imaging in these sicker patients rather than a clinical factor contributing to their clinical course.