Cold air challenge in children with asthma

Abstract

A study was designed to determine the sensitivity and specificity of a cold air bronchial provocation test. A total of 18 children with asthma (mean age 12 years) and 18 normal children (mean age 14 years) were studied. The cold air challenge consisted of a 4 min period of isocapnic hyperventilation of subfreezing air (mean temperature -15 degrees C). In-Induced response in forced expiratory volume in 1 sec (FEV1) expressed as a percentage of predicted normal values was obtained at 4, 6, and 8 min post-challenge. The average response to the cold air was a 27% decrease of FEV1 in asthmatics, which was significantly different from that of the normal children, who showed no statistically significant drop. In both the asthmatic and normal groups, the maximal drop in FEV1 had occurred by the time measurements 4 min post-challenge had been made. At that time, the smallest overlap was observed between normal and asthmatic children. This suggests that the fourth minute post-challenge can be chosen as a cut-off time to distinguish normal from asthmatic children. Considering a decrease of FEV1 greater than 10% as a positive test, the sensitivity of the cold air challenge was 95% and the specificity was 89%.

Comparing methods for assessing bronchial responsiveness in children: single step cold air challenge, multiple step cold air challenge, and histamine provocation

“…Some paediatric groups have standardized a relatively simple SSCACh [1][2][3][4][5], whilst other authors have advocated a more complex multiple step approach [6]. The present study, as the first directly comparative evaluation of these two techniques, demonstrates that there is little reason for going through a time-consuming MSCACh protocol.…”

“…Several paediatric groups have advocated a single step approach, i.e. single step cold air challenge (SSCACh); after applying one dose of cold dry air hyperventilation, the subject's response is quantified in terms of lung function changes effected [1][2][3][4][5]. Other authors have developed a multiple step approach with progressively increasing levels of cold dry air hyperventilation, i.e.…”

Cold air challenge of airway reactivity in children: A correlation of transcutaneously measured oxygen tension and conventional lung functions

“…CACh has become a widely established method for measuring nonspecific airway reactivity in children .s- 9 The method stems from the finding that hyperventilation of cold, dry air is one of the major mechanisms for the development of exercise-induced bronchoc~nstriction.~"~~ The initially developed theory of increased respiratory heat loss as an explanation for CACh-induced airway obstruction has been challenged, and increased respiratory water loss with a transient hyperosmolarity of the respiratory mucosa put forward as an alternative hyp~thesis.~'-~' Be it due to a thermal or osmotic stimulus, CACh, i.e., the voluntary isocapnic hyperventilation of cold and dry air, induces ventilation-perfusion mismatching in a similar fashion as do other bronchial provocation methods. Our study documents a close correlation between the changes of Ptco, and the CAChinduced alterations of conventional PFTs.…”

Asthma outcomes: Pulmonary physiology

“…141–143 This wide range is due to the variability in the stringency of the criteria for the clinical diagnosis of asthma. The sensitivity is higher with cold air, compared with room air temperature.…”