Risk factors and outcomes of pneumomediastinum in COVID-19

<bold>Background:</bold> An increased incidence of pneumomediastinum (PNM) has been observed in patients hospitalized with COVID-19 pneumonia. We aimed to identify risk factors for PNM in COVID-19 and investigate the impact of PNM on clinical outcomes. <bold>Methods:</bold> In this multicentre retrospective case-control study, we included 139 consecutive patients with COVID-19 pneumonia and PNM hospitalized from March to July 2020 at ten centres, and a control group of 153 consecutive inpatients with COVID-19 pneumonia and respiratory failure who did not develop PNM during the same period. Clinical, laboratory and radiological characteristics, respiratory support, and outcomes were collected and compared between the two groups. Risk factors of PNM were assessed by multivariable analysis. <bold>Results:</bold> Lung involvement ≥75%, consolidations, BMI <22 kg/m², CRP >150 mg/L, D-dimer >3000 ng/mL FEUs, and smoking exposure >20 pack-year were independently correlated with the occurrence of PNM. Patients with PNM had a longer hospital stay (mean ± SD 31.2 ± 20.2 days vs 19.6 ± 14.2, p<0.001), higher intubation rate (73/139, 52.5% vs 27/153, 17.6%, p <0.001), and in-hospital mortality (68/139, 48.9% vs 36/153, 23.5%, p<0.001) compared to controls. Maximum FiO₂ delivered was 80.4 ± 16.8% in the PNM group and 66.4 ± 19.6% in the no-PNM group, p<0.001. Invasive or non-invasive respiratory support was given to 135/139 (97.1%) PNM patients and 117/153 (76.5%) no-PNM patients, p<0.001. <bold>Conclusion:</bold> Extensive lung parenchyma involvement, consolidations, low BMI, high inflammatory markers, and tobacco exposure are associated with a greater risk of PNM in COVID-19 pneumonia. This complication significantly worsens the outcomes.