Maximal expiratory mouth pressure is a well established test that is used to assess expiratory muscle strength. However, low values are difficult to interpret, as they may result from technical difficulties in performing the test, particularly in patients with facial muscle weakness or bulbar dysfunction. We hypothesized that measuring the gastric pressure during a cough, a natural maneuver recruiting the expiratory muscles, might prove to be a useful additional test in the assessment of expiratory muscle function. Mouth expiratory and cough gastric pressures were measured in 99 healthy volunteers to obtain normal values and in 293 patients referred for respiratory muscle assessment to compare the two measurements. Between-occasion within-subject coefficient of variation, assessed in 24 healthy volunteers, was 10.3% for mouth pressure and 6.9% for cough. Mean +/- SD cough gastric pressure for normal males was 214.4 +/- 42.2 and 165.1 +/- 34.8 cm H2O for females. In 171 patients deemed weak by a low mouth expiratory pressure, 42% had a normal cough gastric pressure. In 105 patients deemed weak by a low cough gastric pressure, 5.7% had a normal expiratory mouth pressure. Low maximal expiratory mouth pressures do not always indicate expiratory muscle weakness. Cough gastric pressure provides a useful complementary test for the assessment of expiratory muscle strength.
Background: COPD is one of the major leading causes of morbidity and mortality worldwide and cigarette smoking is the major risk factor for the development of COPD. The earlier we can detect signs of incipient COPD, the earlier and with greater impact we can advise smokers to cease smoking. In a previous study, smokers 45-55 years old, were invited to perform spirometry. 57 smokers with normal lung function and pre-COPD were identified. Pre-COPD was defined as smokers having FEV% predicted 89-93 for males and 90-93 for females or FEF50 ≤60% predicted. Aim: To compare the occurrence of emphysematous lesions in smokers who had normal lung function and pre-COPD with smokers without pre-COPD by spirometry. Setting: Primary health care centre Brinken, Motala and University hospital in Linköping, Sweden. Method: The study group consisted of 59 smokers with a mean age of 55 years, of which 30 were smokers with normal lung function and pre-COPD and 29 were matched controls, who had normal lung function and no pre-COPD. The subjects performed new spirometry and High Resolution Computed Tomography (HRCT) 3-4 years after selection. Results: The cumulative incidence of COPD in all 59 subjects was 8,5% (5/59) and all were recruited smokers defined as having pre-COPD, 16,7%, (5/30). The presence of emphysema on HRCT was 43% (n = 13) in the group of smokers defined as having pre-COPD and 44% (n = 13) in the control group. Smokers with emphysema, identified on HRCT, had significantly lower BMI (p < 0.001). Conclusion: Emphysema at HRCT, is present before the lung function has deteriorated according to spirometric definitions of COPD. Smokers with emphysema had significantly lower BMI. Low body weight might be a consequence of incipient COPD not detectible by spirometry, primarily as a result of the systemic inflammation present in COPD or simply be a risk factor for developing COPD.
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