Static compliance and driving pressure are associated with ICU mortality in intubated COVID-19 ARDS
Authors: Boscolo Annalisa , Sella Nicolò , Lorenzoni Giulia , Pettenuzzo Tommaso , Pasin Laura , Pretto Chiara , Tocco Martina , Tamburini Enrico , De Cassai Alessandro , Rosi Paolo , Polati Enrico , Donadello Katia , Gottin Leonardo , De Rosa Silvia , Baratto Fabio , Toffoletto Fabio , Ranieri V. Marco , Gregori Dario , Navalesi Paolo ,   COVID-19 VENETO ICU Network, Valeri Ilaria , Andreatta Giulio , Gandolfi Leonardo , Gadaldi Alessandra , Brumana Nicolò , Forin Edoardo , Correale Christelle , Pesenti Elisa , Fregolent Davide , Pirelli Pier Francesco , Marchesin Davide , Perona Matteo , Franchetti Nicola , Della Paolera Michele , Simoni Caterina , Falcioni Tatiana , Tresin Alessandra , Schiavolin Chiara , Schiavi Aldo , Vathi Sonila , Sartori Daria , Sorgato Alice , Pistollato Elisa , Linassi Federico , Serra Eugenio , Pittarello Demetrio , Tiberio Ivo , Bond Ottavia , Michieletto Elisa , Muraro Luisa , Peralta Arianna , Persona Paolo , Petranzan Enrico , Zarantonello Francesco , Graziano Alessandro , Piasentini Eleonora , Bernardi Lorenzo , Pianon Roberto , Badii Flavio , Bosco Enrico , Agostini Moreno , Farnia Antonio , Peta Mario , Calò Mauro Antonio , Meggiolaro Marco , Lazzari Francesco , Martinello Ivan , Fullin Giorgio , Papaccio Francesco , Bonato Alfeo , Sgarabotto Camilla , Montacciani Francesco , Alessandra Parnigotto , Gagliardi Giuseppe , Ferraro Gioconda , Ongaro Luigi , Baiocchi Marco , Danzi Vinicio , Zanatta Paolo , Marchiotto Simonetta , Bassanini Silvia , Zamperini Massimo , Daroui Ivan 
Published: July 2021

Abstract
Background
Pathophysiological features of coronavirus disease 2019-associated acute respiratory distress syndrome (COVID-19 ARDS) were indicated to be somewhat different from those described in nonCOVID-19 ARDS, because of relatively preserved compliance of the respiratory system despite marked hypoxemia. We aim ascertaining whether respiratory system static compliance (Crs), driving pressure (DP), and tidal volume normalized for ideal body weight (VT/kg IBW) at the 1st day of controlled mechanical ventilation are associated with intensive care unit (ICU) mortality in COVID-19 ARDS.

Methods
Observational multicenter cohort study. All consecutive COVID-19 adult patients admitted to 25 ICUs belonging to the COVID-19 VENETO ICU network (February 28th–April 28th, 2020), who received controlled mechanical ventilation, were screened. Only patients fulfilling ARDS criteria and with complete records of Crs, DP and VT/kg IBW within the 1st day of controlled mechanical ventilation were included. Crs, DP and VT/kg IBW were collected in sedated, paralyzed and supine patients.

Results
A total of 704 COVID-19 patients were screened and 241 enrolled. Seventy-one patients (29%) died in ICU. The logistic regression analysis showed that: (1) Crs was not linearly associated with ICU mortality (p value for nonlinearity = 0.01), with a greater risk of death for values < 48 ml/cmH2O; (2) the association between DP and ICU mortality was linear (p value for nonlinearity = 0.68), and increasing DP from 10 to 14 cmH2O caused significant higher odds of in-ICU death (OR 1.45, 95% CI 1.06–1.99); (3) VT/kg IBW was not associated with a significant increase of the risk of death (OR 0.92, 95% CI 0.55–1.52). Multivariable analysis confirmed these findings.

Conclusions
Crs < 48 ml/cmH2O was associated with ICU mortality, while DP was linearly associated with mortality. DP should be kept as low as possible, even in the case of relatively preserved Crs, irrespective of VT/kg IBW, to reduce the risk of death.