Functional Assessment

This chapter is a review on the lung function tests that can be used to confirm occupational asthma (OA). This includes: baseline spirometry; assessment of nonspecific bronchial hyperresponsiveness (NSBH), principally by methacholine tests; serial measurements of peak expiratory flow (PEF) at work and away from work; and specific inhalation challenges (SICs) either in a laboratory or at the workplace. Detailed methodology on assessment of PEF is presented: number of recordings, plotting graphs of serial graphs, visual or objective analytical assessment of graphs. The validity and limitations of this type of assessment are discussed. Assessment of NSBH is also a key adjunct in the investigation of OA, first in confirming that asthma is present and, second, in determining that it is work-related. Occupational challenge tests are considered as the reference test. The authors outline various aspects of this objective testing: serial FEV1 assessment coupled to the assessment of NSBH and inflammation, delivery of occupational agents, methodology of exposure, interpretation, temporal patterns of reactions, overall validity, and limitations. The authors conclude that currently there are at least two options to confirm OA: SICs considered for long as the reference standard, though expensive and time consuming, and a combination of simpler, readily available, and less expensive diagnostic tools (assessment of NHBR, monitoring of PEF, immunological testing) that can be applied in combination and sequentially to achieve a high diagnostic accuracy.