Eucapnic voluntary hyperventilation as a bronchoprovocation technique. Comparison with methacholine inhalation in...

Area of Science:

• Pulmonology
• Allergy and Immunology
• Respiratory Medicine

Background:

• Methacholine inhalation challenge (MIC) is the standard for nonspecific bronchoprovocation challenge (BPC) to assess airway hyperreactivity (AHR).
• Pharmacologic agents like MIC have limitations in epidemiologic studies, driving interest in physical stimuli.
• Eucapnic voluntary hyperventilation (EVH) with dry gas is a developing physical challenge for AHR assessment.

Purpose of the Study:

• To compare the sensitivity of EVH versus MIC in known asthmatics.
• To compare the quantitative responses between EVH and MIC.
• To correlate challenge responses with asthma symptoms, serum IgE, and eosinophil counts.

Main Methods:

• Prospective, randomized, crossover trial involving 16 subjects meeting the American Thoracic Society asthma definition.
• Subjects underwent both EVH and MIC.
• Data analyzed for test sensitivity, quantitative response correlation, and correlation with clinical/biochemical markers.

Main Results:

• EVH sensitivity was 75%, MIC sensitivity was 81%; one subject positive on each test only.
• Quantitative responses to EVH and MIC were correlated (r = -0.60, p = 0.01).
• EVH response correlated with asthma symptom severity (r = 0.62, p = 0.01), while MIC response correlated with serum IgE (r = -0.53, p = 0.04).

Conclusions:

• EVH is a sensitive measure of AHR in asthma and correlates well with symptom severity.
• EVH may be suitable for initial AHR assessment in asthma evaluation.
• EVH is potentially more physiologic, easier, and less expensive than MIC.