Clinical findings include cough, breathlessness, chest tightness with respiration, and wheezing. These symptoms may be mild, moderate, or severe, and be either intermittent or persistent. The chest exam may be normal, even during persistent asthma. A forced expiratory maneuver may uncover wheezing (106).

Although patients with asthma can have normal pulmonary function, persistent asthma usually has a reduction in FEVr An inhaled bronchodilator may allow confirmation of the reversibility of the reduced FEVj by 12% or greater, a diagnostic characteristic of asthma. Across-shift spirometry, when available, can provide objective evidence of occupational asthma. A greater than 10% fall in FEV1 across a work shift is suggestive of an asthmatic response (106). Monitoring at home or work with a peak expiratory flow rate

(PEFR) meter can substantiate a diagnosis of asthma by demonstrating an intra-day (a.m. to p.m.) variability in PEFR of 20% or greater. Attention should also be given to any work-related pattern of change in the PEFR.

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