Ventilatory Defect in Coal Workers with Simple Pneumoconiosis : Early Detection of Functional Abnormalities
Resource
高雄醫學科學雜誌 v.17 n.5 pp.245-252
Journal
高雄醫學科學雜誌,v.17
Journal Issue
n.5
Pages
245-252
Date Issued
2001
Date
2001
Author(s)
LIN, LIN-CHIH
YANG, SHIEH-CHING
LOW, KOK-WEE
Abstract
Airway obstruction is a prominent feature in coal workers' pneumoconiosis (CWP). However, many patients with CWP have even demonstrated a normal forced vital capacity(FVC) and forced expiratory volume in 1s(FEV1). The purpose of this study was to evaluate the ventilatory defect by spirometry and search for parameters, other than FVC and FEV1, suitable for early detection of pulmonary impairment in CWP. A sample of 227 coal miners was selected from the medical clinics of two teaching hospitals. Maximal expira-tory flow volume measurement and determination of functional residual capacity(FRC) and residual volume(RV) were carried out with an automated plethysmograph. The prevalence of airway obstruction(FEV1/FVC < 70%) in this sample of miners was 52. 9%(120/227).There was a progression of functional impairment with the transition from category 0 to categories 2 and 3, no matter what the miners smoking habits. All of the 107 non- obstructed miners had a normal FVC and FEV1. However, the mean values for FEF25-75%(mean forced expira- tory flow during the middle half of FVC) and Vmax50(maximal expiratory flow rate at 50% FVC) were abnormally low, and RV was already elevated, in those nonobstructed subjects with category 1 simple pneumoconiosis. A borderline abno- rmally elevated FRC in the miners with radiological ca- tegory 3 of CWP was also noted. We conclude that the Vmax50, FEF25-75%, and RV appeared to be the discriminative indices for detecting early ventilatory defect in non-obstructed patients with simple CWP. Further studies is still needed to clarify the cause of small airway dysfunction.
Subjects
coal workers' pneumoconiosis
airway obstruction
early detection
compensation