Can bronchodilator response predict bronchial response to methacholine in preschool coughers?

Abstract

The aim of the present study was to determine the relationship between bronchodilator response, assessed by interrupter resistance (Rint), and bronchial reactivity in preschool children with chronic cough. Thirty-eight children coughers (median age 5.0 years, range 2.8-6.4) were tested. Bronchodilator response was recorded within 4 months before methacholine challenge. Response to the latter was assessed using transcutaneous partial pressure of oxygen and Rint. Children were considered responders if a 20% fall in transcutaneous partial pressure of oxygen occurred during the bronchial challenge. Bronchodilator response was not different between responders (n = 24) and nonresponders (n = 14) [median (range) -0.11 (-0.44-0.09) vs. -0.08 (-0.21-0.10) kPa L(-1) sec; respectively]. However, none of the nonresponders had a bronchodilator response larger than -0.21 kPa L(-1) sec, this cutoff had a 100% positive and a 44% negative predictive value to predict a positive methacholine challenge. The relationship between bronchodilator response and bronchial methacholine responsiveness reached the limit of significance (P = 0.048). Furthermore, the magnitude of the bronchodilator response was correlated to the level of methacholine-induced level of bronchoconstriction (P = 0.01), and to the postchallenge bronchodilation (P = 0.04), all values expressed as % predicted. Moreover, the postbronchodilator Rint value obtained with preceding methacholine challenge was lower than the postbronchodilator value without preceding methacholine challenge in 71.4% (10/14) of the nonresponders and in only 33.3% (8/24) of the responders. Conclusions in preschool coughers bronchodilator response, assessed by the interrupter technique, was correlated to the bronchial responsiveness to methacholine. Non responders had a bronchodilator response not larger than -0.21 kPa L(-1) sec.

Bronchial hyperresponsiveness to methacholine/AMP and the bronchodilator response in asthmatic children

“…Several studies have shown that BDR is associated with histamine or methacholine responsiveness in both children and adults with asthma [7][8][9]. Similarly, we found a significant, albeit weak, correlation between BDR and methacholine PC20.…”

“…It has been suggested that BDR is the physiological opposite of bronchoconstrictor responsiveness [6,9], and, therefore, that bronchial challenge tests can be replaced by bronchodilator tests in subjects with airway obstruction. Several studies have shown that BDR is associated with histamine or methacholine responsiveness in both children and adults with asthma [7][8][9].…”

“…Indeed, provocation challenges, when contraindicated for reason of severe airway obstruction, have been replaced by bronchodilator tests. However, studies on the relationship between BHR to histamine or methacholine and BDR have yielded conflicting results; some found a significant correlation [7][8][9], whereas others did not [10,11]. Conversely, there is no information as to whether BDR correlates with BHR to indirect stimuli, such as AMP.…”

Assessment of Airway Bronchodilation by Spirometry Compared to Airway Obstruction in Young Children with Asthma

“…Our study used spirometry to demonstrate airway reversibility in young children. The ability to measure a response to BDR was previously shown by nonspirometric techniques, including force oscillation, specific resistance measured in the plethysmograph [ 18 , 19 ], and the Rint technique [ 20 ]. It is not surprising, therefore, that spirometry could also identify response to BDR in our tested children.…”

Bronchodilator response by interrupter technique to guide management of preschool wheeze

“…Interrupter resistance (Rint) has the advantages of being relatively easily measured using commercially available, handheld equipment, and of an extensive knowledge base of normal values and variability in preschool children 11–15. Although baseline Rint (like baseline spirometry) is not sufficiently sensitive for reliable diagnosis of asthma,16 BDR measured by Rint is able to separate preschool children with asthma from normal controls with reasonably good sensitivity and specificity,17 18 and is correlated with methacholine responsiveness in preschool children with chronic cough 19. Rint has also been able to delineate a dose-response curve to salbutamol in preschool children similar to that using forced expiratory volume in 1 second (FEV 1 ) in older children 20.…”