Fig. 1

Patient recruitment flowchart. Abbreviation ICU, intensive care unit. ^aPatients discharged from the ICU after non-invasive ventilation or intubation for COVID-19 pneumonia. ^bThirty-one patients had oxygen therapy at home; 24 had severe chronic obstructive pulmonary disease Gold stage 3 or 4; 9 had known chronic diffuse interstitial lung disease. ^cRecent thoracic trauma, pneumothorax, unstable spine or pelvis fractures. ^dSix patients had respiratory frequency > 40/min on screening; two showed excessive use of accessory respiratory muscles as judged by the clinician in charge; one had an indication for non-invasive ventilation for acute pulmonary oedema. ^eThree patients had chronic neuromuscular disease; one had an intestinal occlusive syndrome on screening; one had no social insurance