Differences in cardiopulmonary exercise test results by American Thoracic Society/European Respiratory Society-Global Initiative for Chronic Obstructive Lung Disease stage categories and gender.

BACKGROUND: The American Thoracic Society (ATS)/European Respiratory Society (ERS)-Global Initiative for Chronic Obstructive Lung Disease (GOLD) has developed a new staging system based on the degree of airflow obstruction. Its validity to predict exercise capacity as an outcome has not been extensively studied. We hypothesized that exercise performance measured by cardiopulmonary exercise test (CPET) results should decline significantly with each disease stage, independent of gender. METHODS: We examined 453 consecutive incremental CPET and pulmonary function tests performed in patients who had been referred to a single respiratory physiology laboratory in a tertiary care hospital. They were divided into a control group (normal lung function) and ATS/ERS-GOLD stages 1 to 4. We measured anthropometrics, peak work (in watts), peak oxygen uptake (in liters per kilogram per minute and percent predicted), breathing reserve (in percent predicted), and arterial blood gas response. We compared these results between different stages and genders. RESULTS: The mean (+/- SD) age for the entire group was 64 +/- 11 years, the mean FEV(1) was 66 +/- 28%, and the mean body mass index (BMI) was 27.2 +/- 5.82 kg/m(2). Patients in stage 4 were significantly younger (p < 0.001) and had a lower BMI (p < 0.02) compared to those in stages 1 to 3. There was a significant reduction in exercise capacity for patients at every stage except for those in stage 1, who had values similar to those of the control group. Women had better lung function and exercise capacity than men, but the difference disappeared when adjusted by COPD stages. CONCLUSIONS: The ATS/ERS-GOLD staging system can be used to indicate differences in exercise capacity in patients with COPD stages 2 to 4 and to normalize apparent gender disparities. The value of differentiating stage 1 patients requires further studies with different outcomes.

Deep breath reversal and exponential return of methacholine-induced obstruction in asthmatic and nonasthmatic subjects.

A deep breath (DB) during induced obstruction results in a transient reversal with a return to pre-DB levels in both asthmatic and nonasthmatic subjects. The time course of this transient recovery has been reported to be exponential by one group but linear by another group. In the present study, we estimated airway resistance (Raw) from measurements of respiratory system transfer impedance before and after a DB. Nine healthy subjects and nine asthmatic subjects were studied at their maximum response during a methacholine challenge. In all subjects, the DB resulted in a rapid decrease in Raw, which then returned to pre-DB levels. This recovery was well fit with a monoexponential function in both groups, and the time constant was significantly smaller in the asthmatic than the nonasthmatic subjects (11.6 +/- 5.0 and 35.1 +/- 15.9 s, respectively). Obstruction was completely reversed in the nonasthmatic subjects (pre- and postchallenge mean Raw immediately after the DB were 2.03 +/- 0.66 and 2.06 +/- 0.68 cmH2O.l-1.s, respectively), whereas in the asthmatic subjects complete reversal did not occur (2.29 +/- 0.78 and 4.84 +/- 2.64 cmH2O.l-1.s, respectively). Raw after the DB returned to postchallenge, pre-DB values in the nonasthmatic subjects (3.78 +/- 1.56 and 3.97 +/- 1.63 cmH2O.l-1.s, respectively), whereas in the asthmatic subjects it was higher but not significantly so (9.19 +/- 4.95 and 7.14 +/- 3.56 cmH2O.l-1.s, respectively). The monoexponential recovery suggests a first-order process such as airway wall-parenchymal tissue interdependence or renewed constriction of airway smooth muscle.

Electromyographic validation of the mouth pressure-time index: a noninvasive assessment of inspiratory muscle load.

The pressure-time index (PTI = Pmouth/Pi max x Ti/Ttot) has been validated by Ramonatxo (J. Appl. Physiol. 78 (1995) 646 and by Jabour (Am. Rev. Respir. Dis. 144 (1991) 531 as a noninvasive tool for the assessment of inspiratory muscles load. Nobody until now has evaluated the correlation between the PTI and diaphragmatic activity. Further, the PTI has not been compared with another measures of respiratory muscle load such as the transdiaphragmatic pressure index or TTdi. The purpose of our study was to test the hypothesis that the PTI measured at the mouth (PTIm) is a noninvasive reflection of TTdf and electromyographic activity of the diaphragm (EMGdf). We studied 6 patients with COPD and 5 normal individuals at rest and during a CO2 rebreathing trial and simultaneously measured PTIm, TTdi and EMGdi. The curves of PTIm and EMGdi follows the same trend during the CO2 rebreathing trial with strong and significant correlation between these parameters (r = 0.89 P < 0.05 and r = 0.82 P < 0.05 for PaCO2 of 45 and 53 mmHg respectively). We conclude that PTIm measured as Pmouth/Pi max x Ti/Ttot is an adequate noninvasive method that reflect not only the diaphragmatic activity but also the inspiratory muscles load.

Muscle strength and exercise kinetics in COPD patients with a normal fat-free mass index are comparable to control subjects.

STUDY OBJECTIVE: This study was designed to investigate the extent of clinical muscle dysfunction in stable patients with COPD who were attending an out-patient pulmonary clinic compared with that of age-matched control subjects without COPD. DESIGN AND SUBJECTS: Respiratory muscle and hand grip strength, steady-state O(2) kinetics, and body composition were measured in 32 patients with COPD (19 women) [mean (+/- SD) FEV(1), 38 +/- 11% predicted] and 36 age-matched control subjects (13 women). RESULTS: Measurements of handgrip force (mean, 97 +/- 32% vs 106 +/- 26% predicted, respectively), maximal expiratory pressure (mean, 57 +/- 33% vs 61 +/- 22% predicted, respectively), steady-state O(2) kinetics (mean tau, 72 +/- 34 s vs 78 +/- 37 s, respectively) and steady-state CO(2) kinetics (mean tau, 77 +/- 38 s vs 65 +/- 32 s, respectively) at submaximal exercise were similar in patients and control subjects. All the subjects, except for one female COPD patient, had a normal fat-free mass index (FFMI), although on average the FFMI was lower in male patients (19.8 +/- 2.8) than in male control subjects (23.0 +/- 2.8; p < 0.01). CONCLUSIONS: In patients with COPD who were attending a regular outpatient pulmonary clinic, there was no evidence of reduced upper extremity and expiratory muscle strength or prolonged O(2) and CO(2) kinetics during isowork submaximal cardiopulmonary exercise compared to healthy, age-matched control subjects. Also, a normal body composition was found in nearly all COPD patients. This argues against the existence of a clinically significant systemic myopathy in most stable patients with severe COPD and normal FFMI.

Cough and phlegm are important predictors of health status in smokers without COPD.

STUDY OBJECTIVES: The health-related quality of life of smokers without COPD and that of ex-smokers has not been defined. If abnormal, the role of small airways disease and that of cough and phlegm have never been evaluated. Therefore, the aim of the study was to explore whether the differences in quality of life between smokers and ex-smokers could be explained by cough and phlegm, differences in pulmonary function tests, or exercise capacity. DESIGN: Observational, prospective. SETTING: Pulmonary and Critical Care Division, COPD Center at St. Elizabeth's Medical Center. POPULATION: In 36 smokers, 21 ex-smokers (stopped smoking for > 20 years), 19 never-smokers with normal FVC and FEV(1) values, and 41 patients with COPD (FEV(1) 38 +/- 11% predicted [mean +/- SD]), the St. George's Respiratory Questionnaire (SGRQ), pulmonary function tests, and a 6-min walk distance (6MWD) were performed. RESULTS: The total SGRQ scores were worse in current smokers (15 +/- 15) than in ex-smokers (6 +/- 4) or never-smokers (4 +/- 3) [p < 0.05]. As expected, the worst score was seen in COPD (50 +/- 15). After correcting for cough and phlegm, the difference in SGRQ scores between smokers and ex-smokers disappeared. In current and ex-smokers, the SGRQ score was associated with the exposure to pack-years smoking history (r = 0.45, p < 0.01, and r = 0.83, p < 0.0001, respectively) but independent of lung function or exercise parameters (6MWD). CONCLUSIONS: In smokers without COPD, the abnormal SGRQ score is due to the noxious effect of cigarette smoke, resulting in cough and phlegm, independent of its physiologic effects.