Monitoring of peak expiratory flow rates during occupational asthma treatment

The purpose of this study was to evaluate the effect of anti-inflammatory drug treatment on respiratory symptoms and lung function in twelve subjects with occupational asthma while at work. PEFR was monitored for four weeks and antiasthmatic drugs (salbutamol, chromolyn sodium and beclomethasone dipropionate) were administered for three weeks, starting after the first week of PEFR monitoring, in an unchanged working environment. After treatment five subjects became asymptomatic, six improved and one continued to have unchanged work-related asthmatic symptoms. There were only minor increases in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1) and mean forced expiratory flow during the middle half of FVC (FEF25-75). Bronchial reactivity was studied in eleven subjects: six worsened and five improved. PEFR at 0600 h increased by 9.4% in nine responders and decreased by 5.8% in three non-responders. After treatment diurnal variation (DV) in PEFR decreased by 28.4% in responders and 30.8% in non-responders, even if at the fourth week it was 1.75 higher in non-responders compared to responders. In conclusion, in this study a continuous treatment of occupational asthma with anti-inflammatory drugs minimized respiratory symptoms, slightly increased PEFR and greatly reduced DV in PEFR.