Pneumomediastinum in COVID-19: Interplay Between Infection, Inflammation and Ventilation - a Case Series

Abstract

Introduction: Pneumomediastinum is a rare clinical finding defined by air occupying a potential space in the mediastinum. Bilateral pulmonary opacities including consolidations and ground glass opacifications are some of the radiological manifestations of COVID-19 infection. There has been recent sporadic reports of pneumomediastinum in patients with COVID-19. Spontaneous or primary pneumomediastinum generally occurs when no underlying factors can be identified. Secondary pneumomediastinum occurs due to traumatic causes or non-traumatic respiratory diseases or infections. In this case series, we report seven patients with COVID-19 who developed secondary pneumomediastinum and also discuss the lung protective strategies. Case Description: We present this case series in a table format. Seven patients ages 45-77 (63.7+/-) were included. Reverse transcription polymerase chain reaction (RT-PCR) of SARS-CoV-2 nucleic acid was positive and chest X-ray performed in the Emergency Department showed bilateral subpleural opacities in all. All patients required supplemental oxygen and were transferred from medical floor to the Intensive Care Unit due to worsening respiratory distress. Patients were treated according to individual medical requirements and institutional standard of care. None of the patients had any history of smoking or pneumothorax. Five patients presented with constitutional and respiratory symptoms. Six patients (Patients 1, 3-7) were treated with non-invasive ventilation (BiPAP) prior to diagnosis of pneumomediastinum. Two patients (Patients 4, 7) required intubation and mechanical ventilation. Interestingly, patient 2 had pneumomediastinum on admission. Patient 6 developed both pneumomediastinum and pneumothorax (PTX). Five patients developed pneumomediastinum on noninvasive ventilation. BiPAP pressure varied and these patient s IPAP/EPAP values were in the range of 12-18/6-12. Patient 7 developed pneumomediastinum while mechanically ventilated on pressure control mode. Pneumomediastinum for patients 1-7 was managed conservatively. Patient 4 had pneumomediastinum and pneumothorax and so a chest tube was placed. Pneumomediastinum resolved in patients 3-7. Patients 1,2, and 4 died of multi-organ failure. Discussion: Pneumomediastinum has several known causes including trauma of the trachea or esophagus and positive pressure ventilation associated barotrauma. Viral pneumonia has rarely been associated with pneumomediastinum, but inflammatory lung parenchyma damage may also cause alveolar rupture. We postulate that the patients in this case series suffered pneumomediastinum secondary to SARS CoV-2-related inflammatory lung damage which lowered the threshold for non-invasive positive pressure ventilation-mediated barotrauma. Weaning patients off BiPAP to high flow system or intubation and mechanical ventilation should be considered as a potential strategy. Finally, more studies are needed regarding occurrence of pneumomediastinum in COVID-19 to understand the mechanism and prognostic value.