Actualización en la prueba de provocación bronquial con metacolina en el niño / Update in the bronchial challenge test with methacholine in children

This document updates the recommendations of the bronchial challenge test with methacholine in children. It is based primarily on the recommendations contained in the guide on the technical standard of the bronchial challenge test for methacholine from the European Society of Respiratory Diseases. The main change is the recommendation to use PD20 (methacholine dose that causes a 20% drop in FEV1) instead of PC20 (methacholine concentration that causes a 20% drop in FEV1), which allows for comparable results when different devices and different protocols are used.

Este documento actualiza las recomendaciones de la prueba de provocación bronquial con metacolina en niños. Se basa fundamentalmente en las recomendaciones contenidas en la guía sobre el estándar técnico de la prueba de provocación bronquial de metacolina de la Sociedad Europea de Enfermedades Respiratorias. El principal cambio es la recomendación de utilizar la PD20 (dosis de metacolina que provoca una caída de 20% del VEF1) en vez de PC20 (concentración de metacolina que provoca una caída del 20% en el VEF1), lo cual permite tener resultados comparables cuando se usan diferentes dispositivos y diferentes protocolos.

Airway Responsiveness to Inhaled Aspirin is Influenced by Airway Hyperresponsiveness in Asthmatic Patients

BACKGROUND/AIMS: Many patients with aspirin-induced asthma have severe methacholine airway hyperresponsiveness (AHR), suggesting a relationship between aspirin and methacholine in airway response. This study was performed to determine whether methacholine AHR affects the response of asthmatics to inhaled aspirin. METHODS: The clinical records of 207 asthmatic patients who underwent inhalation challenges with both aspirin and methacholine were reviewed retrospectively. An oral aspirin challenge was performed in patients with a negative inhalation response. The bronchial reactivity index (BRindex) was calculated from the percent decrease in lung function divided by the last dose of the stimulus. RESULTS: Forty-one (20.9%) and 14 (7.1%) patients showed a positive response to aspirin following an inhalation and oral challenge, respectively. Only 24.3 and 14.3% of the responders had a history of aspirin intolerance, respectively. The methacholine BRindex was significantly higher in the inhalation responders (1.46 +/- 0.02) than in the oral responders (1.36 +/- 0.03, p < 0.01) and in non-responders (n = 141, 1.37 +/- 0.01, p < 0.001). The aspirin BRindex was significantly correlated with the methacholine BRindex (r = 0.270, p < 0.001). Three of four patients who received the oral challenge, despite a positive inhalation test, showed negative responses to the oral challenge. Two of these patients had severe AHR. CONCLUSIONS: A considerable number of asthmatic patients with no history of aspirin intolerance responded to the inhalation aspirin challenge. The airway response to aspirin was significantly correlated with methacholine-AHR, and a false-positive response to aspirin inhalation test seemed to occur primarily in patients with severe AHR.

Bronchial response to methacholine inhalation challenge in families with and without asthma

This study included 140 subjects; 20 asthmatic patients, 60 as first degree relative to asthmatics and 60 from non-asthmatic families. The results showed that all asthmatic patients were highly responders to methacholine inhalation challenge with a PD20 FEV1 less than 600 ug. The responders in asthmatic families were seven cases, but in non- asthmatics families, only three cases responded to methacholine inhalation challenge. This indicated that bronchial hyperresponse to methacholine is not due to environmental factor alone, but a combination of both environmental and genetic factors are responsible for bronchial hyperreactivity

The role of the methacholine inhalation challenge in adult patients presenting with chronic cough.

One hundred and twenty two patients who were presenting with chronic persistent cough for more than 3-4 weeks were studied. Using anatomical and stepwise approach, we could identify the cause of chronic cough in 96% of the patients. The most common causes were due to postnasal drip syndrome (PND) (45%) and bronchial asthma (26%). We also demonstrated the important role of methacholine inhalation challenge in the diagnostic work up. The procedure could identify the patients who had bronchial hyperresponsiveness (BHR) in 52% of the cases. The severity degree of the BHR was classified into three levels. Mild or nonspecific BHR was defined as PC20 16-25 mg/ml. This could be found in many diseases such as PND and bronchiectasis. Moderate degree of BHR (PC20 8-16 mg/ml) was found in patients with PND and asthma. PC20 of less than 8 mg/ml was considered to be the most severe degree and it seemed to be specific for the diagnosis of asthma (positive predictive value 100%). Other condition that caused chronic cough were drug-induced, especially angiotensin-converting enzyme inhibitors, gastroesophageal reflux disease (GERD), idiopathic pulmonary fibrosis, subgottic cancer and idiopathic cough. These conditions may require invasive diagnostic work up, such as fiberoptic bronchoscopy and tissue biopsy. The treatment of chronic cough was according to the etiology. Thus, the patients presenting with chronic cough should be investigated to identify the cause, and it was not just only the administration of cough suppressant drugs in these patients.

Methacholine inhalation challenge in patients with chronic cough induced by angiotensin-converting enzyme inhibitors.

Angiotensin-converting enzyme inhibitors (ACEI) cause cough in some patients, but the mechanism of this side effect is not clear. Five patients (group I) who had developed chronic cough induced by ACEI were evaluated to determine the bronchial hyperreactivity (BHR) by challenge with methacholine inhalation using a reservoir method at Respiratory Unit, Chulalongkorn Hospital University. Five patients (group II) who did not experience coughing associated with ACEI were also challenged as controls. The results revealed that two patients (40%) in group I demonstrated BHR with the mean PC20 at 15 mg/ml of methacholine solution. On the other hand, none of the patients in group II disclosed BHR. We concluded that coughing during ACEI therapy may be due to an increased inflammatory state in the airway in some susceptible subjects.

Efectos sobre el valor de PC20 al emplear VEF1 mas alto o mas bajo para su cálculo / Effect on PC20 calculated using the highest or the lowest FEV1 value

Existe poca información en niños acerca de cual valor de VEF1, si el más alto o el más bajo, debe ser considerado para el cálculo de la PC20 de metacolina. Veinte niños asmáticos atópicos, previamente entrenados hasta alcanzar maniobras de capacidad vital forzada reproducibles, fueron estudiados para determinar si había diferencias en las PC20 de metacolina calculadas con los mayores o los menores valores de VEF1. Las diferencias entre las PC20 usando uno u otro valor de VEF1 no fueron estadísticamente significativas (ANOVA). Hubo una correlación significativa entre las PC20 calculadas con ambos métodos (r= 0,93, p< 0,05). El presente estudio demuestra que, en niños asmáticos entrenados hasta lograr maniobras de capacidad vital forzada reproducible, la PC20 puede ser determinada usando el valor más alto o más bajo de VEF1

Standardization of methacholine inhalation challenge by a reservoir method.

Standardization of methacholine inhalation challenge (MIC) by a reservoir method was performed at Respiratory Unit, Chulalongkorn Hospital. One hundred subjects, including 20 non-smoking healthy subjects, 20 patients with isolated chronic cough, 20 patients with isolated allergic rhinitis, 20 patients with stable chronic obstructive bronchitis, and 20 patients with mild bronchial asthma, were scheduled to perform the test. The aerosolized methacholine was produced by an atomized nebulizer of the Provocation test I (Pari-Starnberg) and the aerosol was kept in a reservoir bag. It was inhaled by each subject via a slow vital capacity. Increasing concentrations of methacholine (0, 0.5, 1, 5, 10, and 25 mg/ml were used. None of the healthy subjects had increased bronchial hyperresponsiveness (BHR). Sixty percent of patients with chronic cough, 60% of patients with allergic rhinitis, 95% of patients with chronic obstructive bronchitis, and 100% of patients with asthma were found to be positive in the MIC tests. No serious effect from methacholine during and after the tests was found. It was concluded that MIC can be easily performed by a reservoir with reproducible results to demonstrate BHR.