Mechanisms of orthopnoea in patients with advanced COPD.

Many patients with severe chronic obstructive pulmonary disease (COPD) report an unpleasant respiratory sensation at rest, which is further amplified by adoption of a supine position (orthopnoea). The mechanisms of this acute symptomatic deterioration are poorly understood.Sixteen patients with advanced COPD and a history of orthopnoea and 16 age- and sex-matched healthy controls underwent pulmonary function tests (PFTs) and detailed sensory-mechanical measurements including inspiratory neural drive (IND) assessed by diaphragm electromyography (EMGdi), oesophageal pressure (P es) and gastric pressure (P ga), in both sitting and supine positions.Patients had severe airflow obstruction (forced expiratory volume in 1 s (FEV1): 40±18% pred) and lung hyperinflation. Regardless of the position, patients had lower inspiratory capacity (IC) and higher IND for a given tidal volume (V T) (i.e. greater neuromechanical dissociation (NMD)), higher intensity of breathing discomfort, higher minute ventilation (V'E) and higher breathing frequency (f B) compared with controls (all p<0.05). For controls in a supine position, IC increased by 0.48 L versus sitting erect, with a small drop in V'E, mainly due to reduced f B (all p<0.05). By contrast, IC remained unaltered in patients with COPD, but dynamic lung compliance (C Ldyn) decreased (p<0.05) in the supine position. Breathing discomfort, inspiratory work of breathing (WOB), inspiratory effort, IND, NMD and neuroventilatory uncoupling all increased in COPD patients in the supine position (p<0.05), but not in the healthy controls. Orthopnoea was associated with acute changes in IND (r=0.65, p=0.01), neuroventilatory uncoupling (r=0.76, p=0.001) and NMD (r=0.73, p=0.002).In COPD, onset of orthopnoea coincided with an abrupt increase in elastic loading of the inspiratory muscles in recumbency, in association with increased IND and greater NMD of the respiratory system.

Impact of a Specialized Ambulatory Clinic on Refractory Breathlessness in Subjects With Advanced COPD.

BACKGROUND: Severe exertional dyspnea is a commonly reported symptom in patients with COPD, especially in the advanced stages. Our objective was to assess the preliminary impact of comprehensive, individualized management provided by a specialized tertiary center clinic on exertional dyspnea and patient-centered outcomes in patients with advanced COPD. METHODS: This retrospective analysis included 45 subjects with COPD who were evaluated in a newly established dyspnea clinic over 3 years. Those with severe exertional dyspnea (Medical Research Council dyspnea score of ≥4/5), despite optimal disease-targeted therapy were eligible for referral. We used the revised Edmonton Symptom Assessment System (ESAS-r) to assess symptoms. Responders were defined as those whose change from baseline to 2-months met the minimum clinically important difference of ≤-1 in ESAS-r score for shortness of breath. RESULTS: Subjects (mean ± SD age 70 ± 7 years) had an average FEV1 of 36 ± 18% predicted and a Medical Research Council dyspnea score of 4.7 ± 0.4. Responses to the intervention were variable and mean change in the ESAS-r score for shortness of breath in the total group was -0.32 ± 3.39, P = .53. Forty-seven percent of the subjects were identified as responders, and 42, 40, 40, and 33% met the minimum clinically important difference for improvement in ESAS-r scores for tiredness, anxiety, well-being, and depression, respectively. Responders had fewer emergency department annual visits in the 2 years after their first clinic visit compared with nonresponders (mean ± SD, 1.38 ± 1.63 vs 4.45 ± 5.52, P = .034). CONCLUSIONS: Although the impact of our specialized advanced dyspnea clinic was variable, as evaluated by the ESAS-r, it provided measurable additional clinically important benefit to almost half of the subjects with advanced COPD and severe refractory dyspnea.