Airway opening pressure in an obese ARDS patient: just the start of airway recruitment

Respiratory mechanics data at PEEP 5 and 16 cmH2O PEEP 5 cmH2O PEEP 16 cmH2O PIP, cmH2O 33 33 Pplat, cmH2O 29 29 PEEPTOT, cmH2O 15 18 PEEPI, cmH2O 10 2 ΔP, cmH2O 14 11 VT, mL 300 300 Pes,ei, cmH2O 25 25 Pes,ee, cmH2O 20 20 CTOT, mL/cmH2O 21 27 Cw, mL/cmH2O 60 60 Clung, mL/cmH2O 33 50 Lung volume,ee, mL 713 730 Lung volume,ei, mL 995 1011 ΔEELV, mL – 16 Abbreviations: Clung lung compliance, CTOT Respiratory system compliance (total), Cw chest wall compliance (chest wall), EELV End-expiratory lung volume, Lung volume, ee End-expiratory lung volume, Lung volume, ei End-inspiratory lung volume, PEEPI Intrinsic PEEP, PEEPTOT Total PEEP, PIP Peak inspiratory pressure, Pplat Plateau pressure, ∆P Driving pressure, Pes,ee End-expiratory esophageal pressure, Pes,ei End-inspiratory esophageal pressure, VT Tidal volume Gas content volumes were calculated from computed tomography (CT) numbers analyzed from -1000 Hounsfield unit (HU) to 0 HU in each voxel [3]. By definition, this kind of measurement excludes any mechanical effect caused by the compliance of the ventilator circuit. [...]AOP can easily be identified as the sharp bend where the volume increases and exceeds the baseline by 4 ml, after an initial segment with increasing pressure, but no change in volume (Fig. 1). [...]we report the new finding that, at least in morbidly obese patients, PEEPTOT can be higher than AOP. Declarations Ethics approval and consent to participate This study was approved by the Jichi Medical University Hospital Bioethics Committee for Clinical Research, approval number A20-103.