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Published on: February 25, 2016
[Methacholine challenge in young children: measurement of resistance by interruption]
1Service de Physiologie, Hôpital, Robert Debré, Paris, France. nicole.beydon@rdb.aphp.fr
Insights
Resistance by interruption (Rint) effectively measures bronchoconstriction in children. A 35% increase in Rint can identify children who respond to methacholine challenge, aiding in diagnosing chronic cough.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
Background:
- Methacholine challenge is used to assess airway hyperresponsiveness.
- Accurate measurement of bronchoconstriction in young children is crucial for diagnosis.
Purpose of the Study:
- To evaluate the measurement of resistance by interruption (Rint) for assessing methacholine-induced bronchoconstriction.
- To establish a threshold for Rint increase to differentiate responders from non-responders in young children.
Main Methods:
- Forty-six children underwent methacholine challenge with Rint and transcutaneous oxygen tension measurements.
- Responders were defined by a ≥20% fall in oxygen tension.
- Baseline Rint and Rint increase during challenge were analyzed.
Main Results:
- Children studied had significantly higher baseline Rint compared to normal values.
- Forty-one children were responders, showing a significant Rint increase (p < 0.04).
- A 35% increase in Rint distinguished responders from non-responders.
Conclusions:
- Interrupter resistance significantly increases during bronchial provocation in responding young children.
- Rint measurement is a viable method to quantify bronchoconstriction degree in pediatric patients.
- A 35% Rint increase threshold aids in identifying responders with chronic cough.
Abstract:
The aims of this study were 1. To evaluate the measurement of resistance by interruption (Rint) of bronchoconstriction induced by inhalation of methacholine and 2. To determine a threshold of increase of resistance in young children to differentiate responders from non-responders. Forty-six children (mean age 5 [4.3-6.1] years) referred for methacholine challenge were tested by measurement of Rint and transcutaneous oxygen tension. A fall of 20% or more in oxygen tension from the baseline was used to define the responders. The children studied had a baseline Rint significantly higher than normal (0.84 [0.68-1.01] vs. 0.76 [0.60-0.90] kPa L(-1)s; p < 0.03). Forty-one children were responders and had an increase in Rint significantly different from the non-responders (p < 0/04). An increase in Rint of 35% distinguished responders from non-responders in young children with chronic cough. Interrupter resistance increases significantly during bronchial provocation in responding young children and may be used to measure the degree of bronchoconstriction.
