Application of average volume assured pressure support (AVAPS) and ultrasound assessment in COVID-19 infection: real-life observation

BACKGROUND: ARDS in COVID-19 patients admitted to Emergency Departments (ED) is characterized by reduced diaphragm motility and increased work of breathing (WOB) by accessory respiratory muscles. Reduced perfusion of compliant lungs as consequence of vascular abnormalities has been highlighted as possible explanation of typical hypoxemia. Non-invasive mechanical ventilation (NIMV) has been proposed to treat ARDS. AVAPS is a hybrid modality of NIMV combining features of pressure and volume ventilation. METHODS: we enrolled 38 patients with COVID-19 ARDS to whom we applied NIMV with AVAPS modality. We assessed Tidal Volume (TV), diaphragm excursion (DE) and PaO2/FiO2 before starting NIMV and after three (T3) and six hours (T6) of ventilation. RESULTS: Admissions to ICU were avoided in 68% of our patients. TV (627±147.6 vs. 747.1±226 mL, P<0.00005) and DE (21.8±5.4 vs. 17.9±6.1 mm, P<0.00005) already improved after three hours of AVAPS. TV (521.5±120 mL, P<0.00005), DE (25.8±6.9 mm, P<0.00005) and PaO2/FiO2 (197.3±75.3 vs. 158±67.7, P<0.005) significantly improved in our cohort of patients after six hours. CONCLUSIONS: NIMV with AVAPS modality can be confidently used in the clinical management of COVID-19 patients with ARDS, since AVAPS has positive effects on ventilation-perfusion matching and WOB. We recommend low PEEP value and ultrasound assessment of diaphragm motility and lung characteristics, although further studies are needed to individuate clinical features of NIMV best-responder patients.