BRONCHOPROVOCATION WITH METHACHOLINE IN CHILDREN UNDER 2 YEARS OLD - A FOLLOW-UP-STUDY

Fifty-one wheezing babies (WB) under two years of age and 20 controls (C) within the same age range were submitted to a bronchial provocatio n test (BPT) with methacholine. The appearance of wheezing on pulmonar y auscultation was used to determine PCW (provocative concentration of methacholine causing wheezing). For all tests, methacholine diluted i n saline at increasing concentrations (0.025, 0.125, 0.25, 0.5, 1.0, 2 .5, 5.0 and 10.0 mg/ml) was delivered with O-2 (5 ml/min) via a face m ask. Solution was inhaled through the mouth and nose during two minute s of quiet tidal breathing via a nebulizer containing a 2 ml volume. N o collateral effects were observed, except for tachypnea and tachycard ia. There was a statistically significant difference between the PCW f or WB (2.3 mg/ml) and the PCW for C (9.2 mg/ml). A 5 mg/ml concentrati on of methacholine provides the dearest distinction between the WB and C groups. Indeed, we observed that 96% of WB and 25% of C demonstrate d PCW below this concentration. In the WB group, those with mild sympt oms had higher PCW values. When the BPT was repeated in 27 WB at an 8- month interval, statistically significant differences between the two PCV values were observed The highest PCW values were evidenced in the second BPT. The use of BPT with methacholine could establish PCW as a parameter of bronchial hyperreactivity in infants.