"Pneumomediastinum: A marker of severity in Covid-19 disease"

Abstract

Objective: The goal of this study was to look at the incidence, risk factors, clinical characteristics, and radiological aspects of COVID-19 patients who developed pneumomediastinum and compare these features between those who died and those who survived.

Materials and methods: This retrospective observational study included COVID-19 patients having pneumomediastinum on CT from May 2020 to May 2021 in a COVID-19 care hospital. 1st wave patients were considered between the period of May 2020 to January 2021 and those in the second wave between February 2021 to May 2021. The clinical details were analyzed by a consultant intensivist and CT scans were read by a team of 6 resident radiologists and 5 experienced radiologists. Demographic data, co-morbidities, clinical parameters, hemodynamic markers, radiological involvement and associated complications were analyzed.

Results: During the study period, 10,605 COVID-19 patients were admitted to our hospital of which 5689 underwent CT scan. 66 patients were detected to have pneumomediastinum on CT; 26 of them in the first wave and 40 in the second wave. Out of 66, 28 patients were admitted to ICU, 9 during the first wave and 18 during the second wave. The overall incidence of developing pneumomediastinum was 1.16%. Incidence in the 1st wave was 1.0% and in the 2nd wave was 1.29%. The overall mortality rate in admitted COVID-19 patients was 12.83% while it was 43.9% in COVID-19 patients who developed pneumomediastinum. Incidence of pneumomediastinum and pneumothorax was high in patients with extensive parenchymal involvement. 59/66 (89%) cases of pneumomediastinum had severe CT score on imaging.

Conclusion: We conclude that pneumomediastinum is a marker of poor prognosis. Timely diagnosis of interstitial emphysema or pneumomediastinum will aid in planning early protective ventilation strategies and timely intervention of complications.

Keywords: Barotrauma; COVID-19; Macklin effect; Pneumomediastinum; Pneumothorax.

Fig. 1

Coronal reformatted (A), Sagittal reformatted (B) and axial (C and D) CT images in lung window showing the presence of Macklin effect i. e air dissection along the peribronchovascular sheaths (marked by white arrow).

Fig. 2

Flowchart showing distribution of admitted COVID- 19 patients in both the waves.

Fig. 3

Distribution of co-morbidity.

Fig. 4

Cystic lung pathologies in COVID-19 patients predisposing to pneumomediastinum. A: Axial CT image in lung window showing the presence of multiple small lung parenchymal cysts (marked by white arrow). B: Axial CT image in lung window showing the presence of an emphysematous bulla in the right lower lobe (marked by white arrow). C, D: Case of Autosomal dominant polycystic kidney disease showing C: Presence of lung cysts in axial CT image in lung window (marked by white arrow). D: Multiple hepatic and renal cysts in axial CT image in soft tissue window (marked by white arrow).

Fig. 5

Segmental distribution of subcutaneous and mediastinal emphysema. Axial (A, C, D) and Sagittal reformatted (B) CT images in lung window showing A: Subcutaneous emphysema in the neck region (long arrow) and epidural pneumorrhachis (short arrow), B: Tension pneumomediastinum (marked by white arrow)., C: Subcutaneous emphysema in the chest wall (marked by white arrow), D: Subcutaneous emphysema in the abdominal wall (marked by white arrow).

Fig. 6

KM curve showing cumulative survival against the duration between PM to the death.

Fig. 7

Overview of “Mortality rates”. A) In admitted COVID-19 patients B) In those admitted COVID-19 patients who developed pneumomediastinum.