• Jose Dianti, Samira Fard, Jenna Wong, ChanTimothy C YTCYDepartment of Mechanical and Industrial Engineering, University of Toronto, Toronto, Canada., Lorenzo Del Sorbo, Eddy Fan, AmatoMarcelo B PassosMBPHeart Institute (Incor), Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil., John Granton, Lisa Burry, W Darlene Reid, Binghao Zhang, Damian Ratano, Shaf Keshavjee, Arthur S Slutsky, Laurent J Brochard, Niall D Ferguson, and Ewan C Goligher.
• Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada.
• Crit Care. 2022 Aug 29; 26 (1): 259259.

BackgroundInsufficient or excessive respiratory effort during acute hypoxemic respiratory failure (AHRF) increases the risk of lung and diaphragm injury. We sought to establish whether respiratory effort can be optimized to achieve lung- and diaphragm-protective (LDP) targets (esophageal pressure swing - 3 to - 8 cm H2O; dynamic transpulmonary driving pressure ≤ 15 cm H2O) during AHRF.MethodsIn patients with early AHRF, spontaneous breathing was initiated as soon as passive ventilation was not deemed mandatory. Inspiratory pressure, sedation, positive end-expiratory pressure (PEEP), and sweep gas flow (in patients receiving veno-venous extracorporeal membrane oxygenation (VV-ECMO)) were systematically titrated to achieve LDP targets. Additionally, partial neuromuscular blockade (pNMBA) was administered in patients with refractory excessive respiratory effort.ResultsOf 30 patients enrolled, most had severe AHRF; 16 required VV-ECMO. Respiratory effort was absent in all at enrolment. After initiating spontaneous breathing, most exhibited high respiratory effort and only 6/30 met LDP targets. After titrating ventilation, sedation, and sweep gas flow, LDP targets were achieved in 20/30. LDP targets were more likely to be achieved in patients on VV-ECMO (median OR 10, 95% CrI 2, 81) and at the PEEP level associated with improved dynamic compliance (median OR 33, 95% CrI 5, 898). Administration of pNMBA to patients with refractory excessive effort was well-tolerated and effectively achieved LDP targets.ConclusionRespiratory effort is frequently absent  under deep sedation but becomes excessive when spontaneous breathing is permitted in patients with moderate or severe AHRF. Systematically titrating ventilation and sedation can optimize respiratory effort for lung and diaphragm protection in most patients. VV-ECMO can greatly facilitate the delivery of a LDP strategy.Trial RegistrationThis trial was registered in Clinicaltrials.gov in August 2018 (NCT03612583).© 2022. The Author(s).

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