Methacholine challenge in young children as evaluated by spirometry and impulse oscillometry.
BACKGROUND
In young children, it is difficult to obtain a reproducible flow-volume curve throughout all stages of bronchial challenge. The forced oscillation technique (FOT) is especially established in paediatrics because this method does not require forced or maximal manoeuvres and is less cooperation-dependent than conventional spirometry.


OBJECTIVE
To evaluate the association of spirometric and impulse oscillometric (IOS) indices in a short protocol for methacholine provocation.


METHODS
The primary endpoint was the methacholine dose that caused a 20% decrease in FEV(1) (PD(-20)FEV(1)) compared to baseline. Changes in respiratory resistance (Rrs5) and reactance (Xrs5) acquired by IOS were compared with FEV(1).


RESULTS
Forty-eight children (5.3 ± 0.9 years) were challenged. The mean maximal reduction in FEV(1) was 29.8% ± 14.7 (p < 0.0001), the mean increase in Rsr5 was 55.3% ± 31.7, and the mean decrease in Xrs5 was 0.37 kPa s L(-1) ± 0.23 (p < 0.001). An increase in Rrs5 of 45.2% and a decrease in Xrs5 of 0.69 kPa s L(-1) showed the optimal combination of sensitivity and specificity to detect a 20% reduction in FEV(1) (0.72 and 0.73; 0.80 and 0.76, respectively), and the area under the ROC curve was 0.76 and 0.81, respectively (p < 0.005). In 28 patients with significant changes in FEV(1) and Rsr5, the PD(-20)FEV(1) was 0.48 mg methacholine ±0.59 and the PD(+40)Rrs5 was 0.28 mg methacholine ±0.45 (p = 0.03).


CONCLUSIONS
A short protocol for methacholine challenge testing is feasible in young children. IOS detected 70-80% of patients who responded in spirometry. During the challenge, the Rrs5 response preceded the FEV(1) response.
Department of Allergy, Pulmonology and Cystic Fibrosis Children's Hospital, Goethe-University, Theodor Stern Kai 7, 60590 Frankfurt, Germany. johannes.schulze@kgu.de
Johannes
J
Schulze
Hans-Juergen
HJ
Smith
Johannes
J
Fuchs
Eva
E
Herrmann
Melanie
M
Dressler
Markus A
MA
Rose
Stefan
S
Zielen
D000403:Airway Resistance / Q000502:physiology; D001249:Asthma / Q000175:diagnosis* / Q000503:physiopathology; D001985:Bronchial Provocation Tests / Q000379:methods*; D016085:Bronchoconstrictor Agents; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005240:Feasibility Studies; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D009991:Oscillometry / Q000379:methods; D013147:Spirometry / Q000379:methods; D014797:Vital Capacity / Q000502:physiology
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride