RT Journal Article SR Electronic T1 Quantitative Computed Tomography and Response to Pronation in COVID-19 ARDS JF Respiratory Care FD American Association for Respiratory Care SP 1380 OP 1391 DO 10.4187/respcare.11625 VO 69 IS 11 A1 Zadek, Francesco A1 Berta, Luca A1 Zorzi, Giulia A1 Ubiali, Stefania A1 Bonaiti, Amos A1 Tundo, Giulia A1 Brunoni, Beatrice A1 Marrazzo, Francesco A1 Giudici, Riccardo A1 Rossi, Anna A1 Rizzetto, Francesco A1 Bernasconi, Davide Paolo A1 Vanzulli, Angelo A1 Colombo, Paola Enrica A1 Fumagalli, Roberto A1 Torresin, Alberto A1 Langer, Thomas YR 2024 UL http://rc.rcjournal.com/content/69/11/1380.abstract AB BACKGROUND: The use of prone position (PP) has been widespread during the COVID-19 pandemic. Whereas it has demonstrated benefits, including improved oxygenation and lung aeration, the factors influencing the response in terms of gas exchange to PP remain unclear. In particular, the association between baseline quantitative computed tomography (CT) scan results and gas exchange response to PP in invasively ventilated subjects with COVID-19 ARDS is unknown. The present study aimed to compare baseline quantitative CT results between subjects responding to PP in terms of oxygenation or CO2 clearance and those who did not.METHODS: This was a single-center, retrospective observational study including critically ill, invasively ventilated subjects with COVID-19–related ARDS admitted to the ICUs of Niguarda Hospital between March 2020–November 2021. Blood gas samples were collected before and after PP. Subjects in whom the PaO2/FIO2 increase was ≥ 20 mm Hg after PP were defined as oxygen responders. CO2 responders were defined when the ventilatory ratio (VR) decreased during PP. Automated quantitative CT analyses were performed to obtain tissue mass and density of the lungs.RESULTS: One hundred twenty-five subjects were enrolled, of which 116 (93%) were O2 responders and 51 (41%) CO2 responders. No difference in quantitative CT characteristics and oxygen were observed between responders and non-responders (tissue mass 1,532 ± 396 g vs 1,654 ± 304 g, P = .28; density −544 ± 109 HU vs −562 ± 58 HU P = .42). Similar findings were observed when dividing the population according to CO2 response (tissue mass 1,551 ± 412 g vs 1,534 ± 377 g, P = .89; density −545 ± 123 HU vs −546 ± 94 HU, P = .99).CONCLUSIONS: Most subjects with COVID-19–related ARDS improved their oxygenation at the first pronation cycle. The study suggests that baseline quantitative CT scan data were not associated with the response to PP in oxygenation or CO2 in mechanically ventilated subjects with COVID-19–related ARDS.