Hypocapnia as a predictor of the need for non-invasive mechanical ventilation in subjects with SARS-CoV-2 related pneumonia

SARS-CoV-2 related pneumonia is characterized by moderate-to severe hypoxemia often associated with hypocapnia the prog-nostic role of which is poorely documented. Our aim in the present study was to evaluate if hypocapnia can predict the need for NonInvasive Mechanical Ventilation (NIMV) in this setting. We prospectively studied 52 subjects with moderate-severe SARS-CoV-2 related pneumonia. All the following data were collected at admission to the Emergency Department and processed by unuvariate and multivariate analysis: clinical and laboratory data, blood gas analysis in room air and lung ultrasound. A total of 33 out of 52 subjects (63.4%) underwent NIMV. At univariate analysis PaCO2 was inversely associated to the need for NIMV (OR 0.82, CI 95% 0.689-0.976, p 0.025). At multivariate analysis PaCO2 predicted the need for NIMV independently from age, gen-der, number of comorbidities, d-dimer, CRP, PaO2 and LUS SCORE (OR 0.838, CI 95% 0.710-0.988, p .035). Our data suggest that hypocapnia could be an early predictor of clinical worsening in these patients independently from other known predictors of unfavourable outcome, reflecting the occurrence of a deep and fre-quent respiratory pattern possibly related to the generation of excessive transpulmonary pressure swings leading to a Self-Induced Lung Injury (P-SILI). Further studies are needed for vali-dating these data on greater populations.