Abnormal Activity of Neck Inspiratory Muscles during Sleep as a Prognostic Indicator in Chronic Obstructive Pulmonary Disease

Rationale: In patients with chronic obstructive pulmonary disease (COPD), increased activity of neck inspiratory muscles has been reported as a compensatory response to hyperinflation-related diaphragmatic dysfunction. The persistence of this activity during sleep could attenuate sleep-related hypoventilation and also negatively impact sleep and clinical outcomes.Objectives: To assess the persistence of neck-muscle activity during sleep in patients with COPD recovering from severe exacerbations (i.e., requiring hospitalization) and its impact on sleep quality and recurrence of exacerbations.Methods: Video polysomnography with neck-muscle EMG was performed in patients with COPD who were recovering from a severe exacerbation. The follow-up period lasted 6 months to record the next severe exacerbation.Measurements and Main Results: Twenty-nine patients were included in the study (median [25th-75th percentile] age, 71 [64-72] yr; 55% male; body mass index, 24 [21-29]; FEV1% predicted, 37 [29-45]; and BODE [body mass index, airflow obstruction, dyspnea, and exercise] index, 6 [5-7]). Twenty-six of these patients exhibited sleep-related neck-muscle activity, which was intermittent (limited to stage 3 sleep) in 17 and permanent throughout sleep in 9. α-Delta EEG activity during stage 3 sleep was observed in 87% of the patients. Compared with patients with no or intermittent neck-muscle activity, those with permanent neck-muscle activity showed more disrupted sleep, had experienced more exacerbations in the previous year, and suffered their next severe exacerbation earlier.Conclusions: Sleep-related neck-muscle activity occurs frequently in patients with COPD who are recovering from a severe exacerbation and seems to negatively affect sleep quality and prognosis; therefore, identification of this activity might improve COPD management after a severe exacerbation.