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Autotitrating external positive end-expiratory airway pressure to abolish expiratory flow limitation during tidal breathing in patients with severe COPD: a physiological study

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Eui Sik Suh, Pasquale Pompilio, Swapna Mandal, Peter Hill, Georgios Kaltsakas, Patrick B. Murphy, Robert Romano, John Moxham, Raffaele Dellaca, Nicholas Hart

Original languageEnglish
Article number1902234
JournalThe European respiratory journal
Volume56
Issue number3
DOIs
Published1 Sep 2020

King's Authors

Abstract

Background: The optimal noninvasive application of external positive end-expiratory pressure (EPAP) to abolish tidal-breathing expiratory flow limitation (EFL T) and minimise intrinsic positive end-expiratory pressure (PEEP i) is challenging in COPD patients. We investigated whether auto-titrating EPAP, using the forced oscillation technique (FOT) to detect and abolish EFL T, would minimise PEEP i, work of breathing and neural respiratory drive (NRD) in patients with severe COPD. Methods: Patients with COPD with chronic respiratory failure underwent auto-titration of EPAP using a FOT-based algorithm that detected EFL T. Once optimal EPAP was identified, manual titration was performed to assess NRD (using diaphragm and parasternal intercostal muscle electromyography, EMG di and EMG para, respectively), transdiaphragmatic inspiratory pressure swings (ΔP di), transdiaphragmatic pressure–time product (PTP di) and PEEP i, between EPAP levels 2 cmH 2O below to 3 cmH 2O above optimal EPAP. Results: Of 10 patients enrolled (age 65±6 years; male 60%; body mass index 27.6±7.2 kg.m −2; forced expiratory volume in 1 s 28.4±8.3% predicted), eight had EFL T, and optimal EPAP was 9 (range 4–13) cmH 2O. NRD was reduced from baseline EPAP at 1 cmH 2O below optimal EPAP on EMG di and at optimal EPAP on EMG para. In addition, at optimal EPAP, PEEP i (0.80±1.27 cmH 2O versus 1.95± 1.70 cmH 2O; p<0.05) was reduced compared with baseline. PTP di (10.3±7.8 cmH 2O·s −1 versus 16.8±8.8 cmH 2O·s −1; p<0.05) and ΔP di (12.4±7.8 cmH 2O versus 18.2±5.1 cmH 2O; p<0.05) were reduced at optimal EPAP+1 cmH 2O compared with baseline. Conclusion: Autotitration of EPAP, using a FOT-based algorithm to abolish EFL T, minimises transdiaphragmatic pressure swings and NRD in patients with COPD and chronic respiratory failure.

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