Functional variables associated with the clinical grade of dyspnoea in coal miners with pneumoconiosis and mild bronchial obstruction.
OBJECTIVE
Dyspnoea is a common symptom in coal miners with pneumoconiosis. Among others, gas exchange disturbances due to airway obstruction or mismatch between ventilation and perfusion may be underlying mechanisms. The validation of dyspnoea by the degree of airway obstruction is controversial, because the extent of airway obstruction often does not correlate with the clinical grade of breathlessness.


METHODS
The association was investigated between breathlessness (self reported, on a six point scale) and indices of submaximal spiroergometry in 66 coal workers with radiographically confirmed pneumoconiosis (International Labour Organisation (ILO) grade of profusion > or =1/0, mean (SD) age 64 (5.5) years, mean (SD) forced expired volume in 1 second (FEV(1)) 77.5 (22.9) % predicted).


RESULTS
The clinical degree of breathlessness was independently associated with minute ventilation/oxygen consumption (VE/VO(2)) ratio (beta 0.423, 95% confidence interval (95% CI) 0.18 to 0.67, p=0.001) and smoking (beta 0.318, 95% CI 0.21 to 1.79, p=0.014) in a multiple linear regression analysis. The VE/VO(2) ratio (beta 0.556, 95% CI 0.20 to 0.90, p=0.003) was also the best predictor of breathlessness when only coal miners with airway obstruction (FEV(1) < 80% predicted) were analyzed.


CONCLUSIONS
The VE/VO(2) ratio as a measurement of mismatch between ventilation and perfusion predicted the clinical grade of breathlessness better than measurements of bronchial obstruction at rest in coal workers with pneumoconiosis.
Bauer
T T
TT
Berufsgenossen- schaftliche Kliniken Bergmannsheil, Abteilung für Pneumologie, Allergologie und Schlafmedizin, Medizinische Klinik und Poliklinik, Bürkle-de-la-Camp- Platz 1, D-44789 Bochum, Germany. torsten.bauer@ruhr-uni-bochum.de
Schultze-Werninghaus
G
G
Kollmeier
J
J
Weber
A
A
Eibel
R
R
Lemke
B
B
Schmidt
E W
EW
D000368:Aged; D001784:Blood Gas Analysis; D003031:Coal; D003371:Cough / Q000097:blood / Q000209:etiology / Q000503:physiopathology; D004417:Dyspnea / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D005080:Exercise Test; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D008906:Mining; D010991:Plethysmography; D011009:Pneumoconiosis / Q000097:blood / Q000150:complications / Q000503:physiopathology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000209:etiology / Q000503:physiopathology*; D012115:Residual Volume / Q000502:physiology; D012720:Severity of Illness Index; D012907:Smoking / Q000503:physiopathology; D013223:Statistics as Topic; D014692:Ventilation-Perfusion Ratio; D014797:Vital Capacity / Q000502:physiology
D003031:Coal