Bilevel non-invasive ventilation during exercise reduces dynamic hyperinflation and improves cycle endurance time in severe to very severe COPD

Science and Research

BACKGROUND: During exercise, dynamic hyperinflation (DH), measured by a reduction in inspiratory capacity (IC), increases exertional dyspnoea and reduces functional capacity in many patients with severe COPD. While non-invasive ventilation (NIV) during exercise can improve exercise duration, the effect on DH is unclear. RESEARCH QUESTIONS: In people with COPD, resting hyperinflation, and evidence of DH during exercise: 1) does bilevel NIV during exercise reduce DH and increase endurance time compared to exercise with no NIV? and 2) does NIV with an individually titrated expiratory positive airway pressure (T-EPAP) reduce DH and increase exercise endurance time more than NIV with a standardised EPAP (S-EPAP) of 5cmH(2)O? STUDY DESIGN AND METHODS: A randomised crossover trial in which investigators and participants were blinded between NIV interventions was performed. Participants (N = 19, FEV(1) 1.02 ± 0.24 litres (39 ± 6% predicted)) completed three constant work rate endurance cycle tests in random order: no NIV; NIV with S-EPAP; and NIV with T-EPAP during exercise. Primary outcomes were isotime IC and exercise endurance time. Outcome measures from each intervention were compared at isotime and at end exercise using a linear mixed model analysis. RESULTS: Compared to no NIV, isotime IC and endurance time were greater with both NIV with S-EPAP (mean difference [95%CI] 0.19 [0.10 to 0.28] litres, 153 [24 to 280] seconds respectively) and T-EPAP (0.22 [0.13 to 0.32] litres, 145 [28 to 259] seconds respectively). There was no difference between NIV with S-EPAP and NIV with T-EPAP. INTERPRETATION: In people with COPD and DH during exercise, NIV during exercise reduced DH and increased cycle endurance time. A standardised EPAP of 5cmH(2)O was adequate to obtain these benefits.