The Effect of Mouth Breathing on Exercise Induced Bronchoconstriction in Children

Background: Exercise induced bronchoconstriction (EIB) is a common finding in the pediatric population. Nose breathing is considered to decreases hyper-responsiveness of the airways. Therefore, nose clip (NC) is used during exercise challenge test (ECT) in adults to increase test sensitivity. Data on the need for NC during ECT in children is scarce. Our aim was to evaluate the effect of breathing with and without NC on EIB in children.

Methods: A prospective study evaluating two ECT’s with/without NC within a month period. Demographic, clinical data, Total Nasal Symptoms Score (TNSS) and Asthma Control Test (ACT) were recorded.

Results: Fifty-four children (mean age 16.7±1.2 y/o, 39% Female) were evaluated. Forty-four returned to visit 2 . At Visit 1 (with NC) baseline FEV1 was 92.8±11.0%pred and 27/44 (61%) had positive ECT (decline≥12% in FEV1) with mean FEV1 drop of 14.7±11.3%pred. At visit 2 ,8.7±7.7 days post visit 1 (without NC), baseline FEV1 was 88.9±11.3%pred (p<0.001), mean FEV1 drop was 9.0±10.1%pred (p<0.001) and only 14/44 (32%) had positive ECT. A total of 14/44 (32%) of children with a positive ECT with a NC turned negative without a NC.

Conclusions: Use of NC during ECT increase the rate of positive tests thus possibly improving the yield of EIB diagnosis in children. Optional physiologic mechanisms could be humidification and warming of the inhaled air through the nose cavity. The findings strengthen the recommendation of nasal blockage during ECT. Larger randomized studies are needed to unfold the full effect of nose breathing during exercise.