Methacholine inhalation challenge in young children: results of testing and follow-up.
The diagnosis of asthma is often difficult in young children because their symptoms may not be typical and pulmonary function testing cannot be performed by the patient. We therefore performed methacholine inhalation challenges (MIC) in 24 patients 1 to 5.8 years of age in whom the diagnosis of asthma was uncertain. These patients had histories of recurrent respiratory symptoms for a mean duration of 2.4 years (range = 0.5 to 5.1) in the absence of other systemic diseases. Testing was done by either the 5-breath technique or 1-min inhalation via face mask until wheezing or coughing and retractions developed or a maximum methacholine concentration of 5 to 25 mg/mL was reached. Eighteen MIC were positive and six negative. The mean provocative dose was 3.0 mg/mL (range = 0.6 to 10). No patients suffered serious or delayed reactions and all symptoms reversed with inhaled bronchodilators (BD). During the MIC, the progression of symptoms often mimicked progression of those observed in the past and was useful in teaching the parents. Patients were followed for 0.5 to 3.8 years (mean = 2.3). All patients with a positive MIC have continued to have recurrent respiratory symptoms and require regular or intermittent BD. Only one patient with a negative MIC at 5 mg/mL has recurrent respiratory symptoms and requires daily BD 3 years after the initial evaluation. We conclude that MIC can safely be performed in young children in whom the diagnosis of asthma is uncertain. A positive MIC in this context demonstrates increased bronchial reactivity and is supportive of a clinical diagnosis of asthma.(ABSTRACT TRUNCATED AT 250 WORDS)
Adinoff
A D
AD
National Jewish Center for Immunology and Respiratory Medicine, Denver, Colorado.
Schlosberg
R T
RT
Strunk
R C
RC
D001249:Asthma / Q000175:diagnosis*; D001985:Bronchial Provocation Tests; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D008297:Male; D008688:Methacholine Compounds
D008688:Methacholine Compounds