Incremental Exercise Testing in Pleuropulmonary Disease due to Inhalation of Inorganic Dusts: Physiologic Dead Space as the Most Sensitive Indicator.
Miller-A; Hailoo-W; Brown-LK
NIOSH 1990 Sep:503-507
A method was presented which correlated various commonly used lung function indices with a number of exercise variables in 43 patients undergoing maximal incremental exercise to evaluate likely pulmonary and/or pleural fibrosis due to the inhalation of inorganic dusts, which in 35 of the cases was asbestos (1332214). The results indicated that an abnormal diffusing capacity (D(L)) reading predicted excessive dead space ventilation often present at rest, and conversely, that this abnormality of gas exchange was frequently present even when D(L) was normal. Of the remaining eight patients, six were occupationally exposed to hard metal and two to beryllium (7440417). The patients demonstrated the full spectrum of disease from radiographically inapparent to minimal to advanced diffuse pulmonary fibrosis. Most complained of dyspnea. The ratio of dead space to tidal volume (V(D)/V(T)) was the most sensitive indicator of abnormality, being increased in 31 of 43 patients. Many of these had normal forced vital capacity (FVC) and/or D(L). FVC was as likely to be abnormal as D(L). Abnormality of one was not very likely to predict abnormality of the other, with roughly half the patients having an abnormal FVC also having a normal D(L). Alveolar/arterial differences for PO2 and ventilatory response during exercise were the least likely to be abnormal. Of the 31 patients with abnormal V(D)/V(T) at rest or exercise, this was manifested in the majority at rest. The authors state that exercise is not usually necessary to demonstrate this derangement of gas exchange.
Diagnostic-techniques; Physical-exercise; Respiratory-system-disorders; Dust-exposure; Lung-disease; Pulmonary-disorders; Pulmonary-function-tests; Lung-function;
DHHS (NIOSH) Publication No. 90-108
Asthma and Chronic Obstructive Pulmonary Disease; Disease and Injury; Respiratory-system-disorders;
Proceedings of the VIIth International Pneumoconioses Conference