PT  - JOURNAL ARTICLE
AU  - Daniel Langer
AU  - Casey Ciavaglia
AU  - Kathy Webb
AU  - J. Alberto Neder
AU  - Denis O'Donnell
TI  - Inspiratory muscle weakness in mildly- to moderately-hyperinflated patients with COPD
DP  - 2014 Sep 01
TA  - European Respiratory Journal
PG  - P3344
VI  - 44
IP  - Suppl 58
4099  - http://erj.ersjournals.com/content/44/Suppl_58/P3344.short
4100  - http://erj.ersjournals.com/content/44/Suppl_58/P3344.full
SO  - Eur Respir J2014 Sep 01; 44
AB  - It is unknown whether inspiratory muscle weakness might be present and related to exertional dyspnea in patients with COPD who are not severely hyperinflated. Clinically stable patients (n=300) underwent complete pulmonary function tests and a maximal incremental cycle exercise test. After excluding patients with severe hyperinflation (IC/TLC<0.25; n=72) we compared patients with reduced (Pi,max<60%pred; n=88) and preserved (Pi,max:≥60%pred; n=140) inspiratory muscle strength (Table).View this table:Characteristics of patients with reduced (Pi,max<60%pred), and preserved (Pi,max≥60%pred) inspiratory muscle strength.Thirty-nine percent of patients in this population had a Pi,max of less than 60% of the predicted normal value. After correcting for resting hyperinflation and other baseline differences (ANCOVA) patients with reduced Pi,max achieved lower peak work rates (W,max: 88±38 vs 76±31 Watt; p=0.004) and oxygen consumption (VO2,max: 1.5±0.6 vs 1.3±0,5 L/min; p=0.001), but higher ventilation-corrected dyspnea scores (0.105±0.052 vs 0.122±0.061; p=0.023). A higher proportion of patients with reduced Pi,max reported 'shallow breathing' at peak exercise (38% vs 20%; p=0.019). Inspiratory muscle weakness in COPD patients is prevalent even in those who are not severely hyperinflated. Inspiratory muscle weakness might contribute to dyspnea and exercise limitation in selected patients.