Steinbrugger B, Eber E, Modl M, Weinhandl E, Zach M S
Pediatric Department, University of Graz, Austria.
Chest. 1995 Sep;108(3):741-5. doi: 10.1378/chest.108.3.741.
It has remained unclear whether bronchial responsiveness as measured by a single-step cold-dry air challenge (CACh) correlates closely to the responsiveness that is assessed by a routine pharmacologic challenge.
On 2 consecutive days, we performed a CACh and a histamine challenge in 128 symptom- and medication-free pediatric and adolescent asthma patients. The CACh consisted of 4 min of isocapnic hyperventilation of -10 degrees C, absolutely dry air; responsiveness was expressed by the induced change in FEV1 (delta FEV1). The histamine challenge consisted of sequential inhalations of incremental increases in concentrations of histamine; responsiveness was expressed by the concentration which caused a 20% fall of FEV1 (PC20).
Five children did not bronchoconstrict sufficiently in the histamine challenge for measuring a PC20 and were excluded from analysis. In the remaining 123, delta FEV1 (CACh) ranged from +5 to -73%, PC20 (histamine) from 0.05 to 7.2 mg/mL. There was a statistically significant correlation between delta FEV1 and PC20 (r = 0.54, p < 0.001), but also a considerable scatter of individual data points around the regression line. Fifty-two subjects were hyperresponsive by CACh and 114 by histamine criteria.
There is a relatively weak correlation between the results of these two challenges; thus, one cannot be substituted one for the other. Histamine appears as more sensitive in detecting airway hyperresponsiveness than CACh. The poor correlation between the responses to these two challenges can be explained by differences between the challenge protocols, or, alternatively, by differences between applied stimuli and activated mechanisms.
通过单步冷干空气激发试验（CACh）所测定的支气管反应性与通过常规药物激发试验所评估的反应性是否密切相关尚不清楚。
在连续两天，我们对128名无症状且未用药的儿童及青少年哮喘患者进行了CACh和组胺激发试验。CACh包括4分钟-10℃、绝对干燥空气的等碳酸通气；反应性通过FEV1的诱导变化（△FEV1）来表示。组胺激发试验包括依次吸入浓度递增的组胺；反应性通过导致FEV1下降20%的浓度（PC20）来表示。
5名儿童在组胺激发试验中支气管收缩不足，无法测量PC20，被排除在分析之外。在其余123名患者中，△FEV1（CACh）范围为+5%至-73%，PC20（组胺）范围为0.05至7.2mg/mL。△FEV1与PC20之间存在统计学显著相关性（r = 0.54，p < 0.001），但各个数据点在回归线周围也有相当大的离散度。根据CACh标准有52名受试者反应性过高，根据组胺标准有114名。
这两种激发试验的结果之间存在相对较弱的相关性；因此，两者不能相互替代。组胺在检测气道高反应性方面似乎比CACh更敏感。这两种激发试验反应之间的相关性较差可以通过激发试验方案的差异来解释，或者也可以通过所应用刺激和激活机制的差异来解释。
