TY - JOUR T1 - Late Breaking Abstract - Positive end-expiratory pressure affects geometry and function of the human diaphragm JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/13993003.congress-2020.3719 VL - 56 IS - suppl 64 SP - 3719 AU - Diana Jansen AU - Annnemijn H. Jonkman AU - Heder J. De Vries AU - J. Tim Marcus AU - Coen A. C. Ottenheijm AU - Leo M. A. Heunks Y1 - 2020/09/07 UR - http://erj.ersjournals.com/content/56/suppl_64/3719.abstract N2 - Background and Aims: Positive end-expiratory pressure (PEEP) is routinely applied in mechanically ventilated patients to improve gas exchange and respiratory mechanics by increasing end-expiratory lung volume. In a recent study in rats, we demonstrated that PEEP causes diaphragm remodeling, especially longitudinal muscle atrophy. The effects of PEEP on the human diaphragm are unknown. Our aim was to investigate the acute in vivo effects of PEEP on human diaphragm geometry and function, as this is a prerequisite for diaphragm remodeling.Methods: Healthy volunteers (n=19) were non-invasively ventilated with PEEP 2, 5, 10 and 15 cmH2O. MRI was performed to investigate PEEP-induced changes in diaphragm geometry. Subjects were instrumented with nasogastric catheters to measure diaphragm neuromechanical efficiency at different PEEP levels. To confirm findings of healthy subjects, dynamic diaphragm MRI was performed in an invasively ventilated patient.Results: Increasing PEEP from 2 to 15 cmH2O resulted in a caudal diaphragm displacement (19 [14-26] mm, P<0.001), muscle shortening in the zones of apposition (20.6% anterior and 32.7% posterior, P<0.001), increase in diaphragm thickness (28.3 [4.9-42.3] %, P=0.002) and reduction in neuromechanical efficiency (48% [37.6-56.6], P<0.001). MRI data confirmed PEEP-induced changes in diaphragm geometry in the invasively ventilated patient.Conclusion: PEEP leads to a caudal displacement of the diaphragm with concomitant muscle shortening and thickening in the zones of apposition, leading to a reduction in diaphragm contractile function. These findings suggest that conditions required to develop longitudinal atrophy in the human diaphragm are present with the application of PEEP.FootnotesCite this article as: European Respiratory Journal 2020; 56: Suppl. 64, 3719.This abstract was presented at the 2020 ERS International Congress, in session “Respiratory viruses in the "pre COVID-19" era”.This is an ERS International Congress abstract. No full-text version is available. Further material to accompany this abstract may be available at www.ers-education.org (ERS member access only). ER -