Asthma Management in a ‘Clean’ Environment: 1. the Effect of Challenge with Foods and Chemicals on the Peak Flow Rate

Abstract

The standard 3-week inpatient regime in the Airedale Allergy Centre for investigation of chronic symptoms involves a 5-day fast, followed by three single-food challenge meals a day. Endpoint titration [1] is used to curtail adverse reactions, and to test inhalants and chemicals.In 19 consecutive asthmatics, the peak expiratory flow rate (PEF) was consistent after some of the 646 food challenges, but fell after others, and was usually restored bv endpoint titration using dilutions of an extract of the trigger food. Bronchoconstriction was provoked and relieved by different dilutions of some of the chemicals and chemical mixtures tested sublingually. Results are demonstrated on continuous PEF charts, each covering nine or more challenges over several days: individuals differed in the profile of foods and chemicals provoking bronchoconstriction.The overall distribution of the maximum change in the PEF after each food challenge in nine patients on no asthma medication in the ‘clean’ conditions differed from the expected best-fit normal distribution (p < -0001); changes of more than 20 l/min were unlikely to have occurred by chance. the PEF fell after all types of food, but there were differences (p < 0.05), with more frequent drops (often delayed) after meat, fish and grains. When the PEF remained low after repeated adverse reactions, recovery most frequently occurred after a fruit meal (p < 0.0001). Genuine increases in the PEF were also noted.