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Updated: Aug 14, 2026
Murine Model of Allergen Induced Asthma
Published on: May 14, 2012
Feasibility of shortened methacholine challenge in preschool children
J Kivastik1, A-M Gibson, R A Primhak
1Academic Unit of Child Health, University of Sheffield, Sheffield, UK.
Abstract:
The aim of our study was to assess the feasibility and safety of a recently suggested tripling-dose methacholine (Mch) challenge in preschool children. Fifty-seven children aged 3-6 years were studied. Mch challenge was carried out using a tidal breathing method, with concentrations of 0.22, 0.66, 2.0, 6.0, and 18.0 mg/ml, at 5-min intervals, given by a Pari Turbo Boy compressor and Pari LC Plus nebulizer, for 1 min only. Oxygen saturation (SaO(2)) was monitored during the challenge. The challenge was terminated if there was wheeze, SaO(2) below 91%, or persistent cough. This final Mch dose was considered the provocative concentration inducing audible wheeze (PCW). Nine healthy children, 17 with cough and 25 with wheeze, completed the study. Mean output from nebulizers (SD) in these 51 children was 0.30 (0.05) ml/min. Geometric means for PCW in these groups were 2.88, 2.58, and 1.28 mg/ml Mch, respectively. The wheezing children were significantly more hyperresponsive than the coughing children (P < 0.05). A tripling-dose Mch protocol is safe and practicable in children over 3 years of age. A further reduction in nebulized dose may be needed for a more discriminatory test.
Insights
A tripling-dose methacholine (Mch) challenge is safe and feasible for preschool children aged 3-6 years. This Mch test helps assess airway hyperresponsiveness in young children.
Area of Science:
- Pediatric Pulmonology
- Respiratory Medicine
- Clinical Trials
Background:
- Airway hyperresponsiveness (AHR) is a key feature of asthma.
- Assessing AHR in preschool children presents unique challenges.
- Standardized methacholine (Mch) challenge protocols are needed for this age group.
Purpose of the Study:
- To evaluate the safety and feasibility of a tripling-dose methacholine (Mch) challenge.
- To assess AHR in preschool children aged 3-6 years using a modified Mch protocol.
- To determine provocative concentrations of Mch causing wheeze (PCW) in different pediatric groups.
Main Methods:
- A prospective study involving 57 children aged 3-6 years.
- Methacholine (Mch) challenge administered via tidal breathing with increasing doses (0.22-18.0 mg/ml).
- Oxygen saturation (SaO2) monitored; challenge stopped for wheeze, SaO2 < 91%, or persistent cough.
Main Results:
- The tripling-dose Mch protocol was completed safely by 51 children.
- Geometric means for PCW were 2.88 mg/ml (healthy), 2.58 mg/ml (cough), and 1.28 mg/ml (wheeze).
- Children with wheeze showed significantly higher hyperresponsiveness compared to those with cough (P < 0.05).
Conclusions:
- A tripling-dose methacholine (Mch) challenge protocol is safe and practicable for children over 3 years.
- The Mch test can identify airway hyperresponsiveness in preschool children.
- Further dose adjustments may enhance the test's discriminatory power.
