Methacholine airway hyperresponsiveness measured just after control of acute severe asthma

Myoung, Bo Hyun; Choi, Inseon S; Park, Seog Chea; Lim, Ho

Abstract

BACKGROUND
It has been shown that severe asthmatic attacks are related to airway hyperresponsiveness (AHR). However, there has been no study on AHR measured just after control of acute severe asthma.
OBJECTIVE
To determine the degree of AHR following acute severe asthma and to evaluate the safety of AHR measurement in patients just recovering from a severe attack. METHOD: In 23 consecutive asthma patients just recovering from a severe attack (10 severe, 13 near-fatal), all medications except inhaled or systemic steroids were withdrawn temporarily for more than each action time. Then a methacholine bronchoprovocation test was performed in patients with FEV1 > or = 75% of predicted or personal best value.
RESULTS
Mean duration required to control asthma was 5.6+/-3.6 days, and methacholine provo- cation test was performed at 12.6+/-5.2 hospital days. The patients showed significantly lower methacholine-PC20 (geometric mean: 0.54 vs 1.64 mg/ml, p<0.05) and steeper slope of dose-response curve (p<0.01) compared to 62 outpatients. Initial FEV1 (r=0.470, p<0.05) and the duration required to control asthma (r=-0.623, p<0.01) were significantly related to methacholine-PC20. However, only 9 patients (39.1%) showed severe AHR, which was not significantly different from outpatients (25.8%).
CONCLUSION
These results suggest that AHR is a risk factor of severe asthmatic attack and methacholine challenge just after control of acute asthma is relatively safe.