Early in the COVID-19 pandemic, a significant series of patients with severe pneumonia were recorded with spontaneous pneumomediastinum (SP), however most of these patients were already receiving invasive mechanical ventilation (IMV) at the time of diagnosis. To determine if IMV produced pneumomediastinum, researchers conducted a retrospective multicenter observational study assessing the prevalence and consequences of SP in severe COVID-19 with pneumonia prior to any IMV.
After a median of 6 days [4-12] in the intensive care unit, 21 out of 549 patients (4%) who were getting non-invasive breathing support developed an SP. There was not a significant difference in the percentage of patients who needed IMV. Non-invasive ventilation was used more frequently in SP patients (n=11; 52% vs. n=150; 28%; P=0.02), however the time to tracheal intubation was longer in SP patients (6 days [5-13] vs. 2 days [1-4]; P=0.00002). There were persistent signs of severe lung disease and respiratory failure in the 21 patients who developed an SP, and the ROX index was lower in the day before the SP occurred than it was on admission to the ICU (3.94 [3.15–5.55] vs. 3.25 [2.73–4.02]; P=0.1), which may highlight potential indirect signals of Patient-self-inflicted lung injury (P-SILI).
SP without IMV was not rare in this set of critically ill COVID-19 patients, impacting 4% of patients. In comparison to controls, they were given vasopressors more frequently and spent more time in the intensive care unit. The delayed use of IMV and the change in the ROX index between the day of ICU admission and the day before SP highlight a putative pathophysiological mechanism carried out by P-SILI associated with protracted respiratory failure.