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P67 Laryngeal Narrowing In Chronic Obstructive Pulmonary Disease (copd): A Mechanism For Generating Intrinsic Peep?
  1. M Baz1,
  2. GS Haji2,
  3. A Menzies-Gow2,
  4. RJ Tanner2,
  5. NS Hopkinson2,
  6. MI Polkey2,
  7. JH Hull2
  1. 1Universidad de La Republica, Montevideo, Uruguay
  2. 2NIHR Respiratory Biomedical Research Unit, Royal Brompton and Harefield NHS Foundation Trust and Imperial College, London, UK

Abstract

Introduction and rationale Patients with COPD often exhibit pursed lip breathing during exercise, a strategy to help overcome a rise in intrinsic PEEP secondary to dynamic hyperinflation. A similar role for laryngeal closure to optimise respiratory mechanics during exertion is postulated.

Objectives Assessment of laryngeal narrowing and its role in exercise intolerance and dynamic hyperinflation in COPD.

Methods and Measurements: We studied 30 age and sex matched subjects (n = 11 healthy, n = 8 mild to moderate COPD, n = 11 severe COPD). Baseline physiological characteristics and clinical status were assessed prior to an incremental maximal cardiopulmonary exercise test with continuous laryngoscopy. Laryngeal narrowing was calculated at the glottic and supra-glottic aperture at rest and peak exercise.

Results Expiratory laryngeal narrowing was pronounced in patients with COPD at rest and peak exercise and related to FEV 1 (r=-0.53, p < 0.05 and r=-0.70, p < 0.001 respectively). Glottic narrowing at peak exercise correlated with inspiratory duty cycle time (Ti/Ttot) (Figure), this was not seen at rest (r=-0.79, P < 0.0001 and r=-0.07, p = 0.77 respectively). Laryngeal closure at peak exercise inversely correlated with peak oxygen uptake (r=-0.68, p < 0.01).

Conclusion Dynamic laryngeal closure during expiration is prevalent in patients with COPD and is related to disease severity, respiratory duty cycle and exercise capacity.

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