PURPOSE: The purpose of this study is to investigate how respiratory muscle strength correlates to cough capacity in patients with respiratory muscle weakness. MATERIALS AND METHODS: Forty-five patients with amyotrophic lateral sclerosis (ALS), 43 with cervical spinal cord injury (SCI), and 42 with Duchenne muscular dystrophy (DMD) were recruited. Pulmonary function tests including forced vital capacity (FVC) and respiratory muscle strength (maximal expiratory pressure, MEP; maximal inspiratory pressure, MIP) were performed. The correlation between respiratory muscle strength and cough capacity was analyzed. RESULTS: In the SCI group, FVC in a supine position (2,597 +/- 648 mL) was significantly higher than FVC in a sitting position (2,304 +/- 564 mL, p < 0.01). Conversely, in the ALS group, FVC sitting (1,370 +/- 604 mL) was significantly higher than in supine (1,168 +/- 599 mL, p < 0.01). In the DMD group, there was no statistically significant difference between FVC while sitting (1,342 +/- 506 mL) and FVC while supine (1,304 +/- 500 mL). In addition, the MEP and MIP of all three groups showed a significant correlation with peak cough flow (PCF) (p < 0.01, Pearson's correlation analysis). In the SCI group, MIP was more closely correlated with PCF, while in the ALS and DMD groups, MEP was more closely correlated with PCF (p < 0.01, multiple regression analysis). CONCLUSION: To generate cough flow, inspiratory muscle strength is significantly more important for SCI patients, while expiratory muscle function is significantly more important for ALS and DMD patients.
Adult ; Amyotrophic Lateral Sclerosis/*physiopathology ; Cough/*physiopathology ; Female ; Humans ; Inspiratory Capacity ; Male ; Middle Aged ; Muscle Strength/*physiology ; Muscle Weakness/pathology/*physiopathology ; Muscular Dystrophy, Duchenne/*physiopathology ; Respiratory Muscles/pathology/*physiopathology ; Spinal Cord Injuries/*physiopathology

OBJECTIVETo investigate the effects of inspiratory muscle training followed by non-invasive positive pressure ventilation in patients with severe chronic obstructive pulmonary disease (COPD).

METHODSThis investigator-initiated randomized, controlled trial recruited 88 patients with stable GOLD stage IV COPD, who were randomized into 4 equal groups to continue oxygen therapy (control group) or to receive inspiratory muscle training followed by non-invasive positive pressure ventilation (IMT-NPPV group), inspiratory muscle training only (IMT group), or noninvasive positive pressure ventilation only (NPPV group) for at least 8 weeks. The outcomes of the patients were assessed including the quality of life (SRI scores), maximum inspiratory pressure (MIP), maximum expiratory pressure (MEP), dyspnea (MRC scores), 6-min walking distance (6MWD) and lung function.

RESULTSs Compared to baseline values, SRI scores, 6MWT and MRC scores increased significantly after 8 weeks in IMT-NPPV, IMT and NPPV groups, and the improvements were significantly greater in IMT-NPPV group than in IMT and NPPV groups (P<0.05 for all). In IMT-NPPV and IMT groups, MIP and MEP increased significantly after the training (P<0.05), and the improvement was more prominent in IMT-NPPV group (P<0.05). No significant changes were found in pulmonary functions in the groups after 8 weeks of treatment (P>0.05).

CONCLUSIONInspiratory muscle training followed by non-invasive positive pressure ventilation, compared with inspiratory muscle training or non-invasive positive pressure ventilation alone, can better enhance the quality of life, strengthen the respiratory muscles, improve exercise tolerance and relieve the dyspnea in patients with COPD.

Dyspnea ; therapy ; Exercise Tolerance ; Humans ; Lung ; physiopathology ; Noninvasive Ventilation ; Physical Conditioning, Human ; Positive-Pressure Respiration ; Pulmonary Disease, Chronic Obstructive ; therapy ; Quality of Life ; Respiratory Muscles ; physiopathology

A reduction in diaphragm mobility has been identified in patients with chronic obstructive pulmonary disease (COPD) and has been associated with a decline in pulmonary function parameters. However, little information exists regarding the potential role of diaphragm mobility on hypercapnia in COPD. A new method of assessing the mobility of the diaphragm, using ultrasound, has recently been validated. The purpose of the present study was to investigate the relationship between diaphragm mobility and pulmonary function parameters, as well as that between arterial blood gas values and diaphragm mobility, in COPD patients. Thirty seven COPD patients were recruited for pulmonary function test, arterial blood gas analysis and diaphragm mobility using ultrasound to measure the craniocaudal displacement of the left branch of the portal vein. There were significant negative correlations between diaphragmatic mobility and PaCO2 (r = -0.373, P = 0.030). Diaphragmatic mobility correlated with airway obstruction (FEV1, r = 0.415, P = 0.011) and with ventilatory capacity (FVC, r = 0.302, P = 0.029; MVV, r = 0.481, P = 0.003). Diaphragmatic mobility also correlated significantly with pulmonary hyperinflation. No relationship was observed between diaphragm mobility and PaO2 (r = -0.028, P = 0.873). These findings support a possibility that the reduction in diaphragm mobility relates to hypercapnia in COPD patients.
Aged ; Airway Resistance/physiology ; Carbon Dioxide/blood/physiology ; Diaphragm/physiopathology/*ultrasonography ; Female ; Humans ; Hypercapnia/complications/*physiopathology ; Male ; Middle Aged ; Portal Vein ; Pulmonary Disease, Chronic Obstructive/complications/*physiopathology/ultrasonography ; Pulmonary Gas Exchange ; Respiratory Muscles/physiopathology