Tahan M, Milot J, Boulet L P
Unité de Recherche, Centre de Pneumologie de l'Hôpital Laval, Université Laval, Québec, Canada.
Ann Allergy. 1994 Sep;73(3):247-51.
The influence of an allergen challenge on recumbency induced changes in airway responsiveness to methacholine was documented in seven nonsmoking subjects with stable mild asthma (3M, 4F).
All subjects spent four hours (8 to 12 AM) in the supine position before and 24 hours after an allergen challenge that induced a dual asthmatic response. FEV1 was measured hourly in the supine position and a methacholine challenge was done in the sitting position before and after each 4-hour period. None used bronchial antiinflammatory drugs before or during the study.
The mean maximal fall in FEV1 (+/- SEM) was 31.0 +/- 1.1% within one hour of the last allergen inhalation and 27.5 +/- 4.9% between two and eight hours later. Presupine/postsupine session FEV1 (%pred +/- SEM) was unchanged either at baseline or postallergen challenge sessions, with values of 89.3 +/- 2.7/88.3 +/- 5.1 and 86.6 +/- 4.2/87.4 +/- 5.7. Presupine/postsupine PC20 methacholine was slightly reduced but this did not reach statistical significance (P > .05), with a mean PC20 (mg/mL) of 0.83 +/- 1.44/0.52 +/- 1.46 (preallergen session); 0.55 +/- 1.44/0.39 +/- 1.37 (postallergen challenge session). This delta PC20 (baseline/post-session) did not differ between the two sessions (P > .05). The delta PC20 was not correlated with the magnitude of the late asthmatic response to allergen nor the postallergen increase in airway responsiveness.
We conclude that an acute allergen challenge does not significantly increase recumbency-induced changes in airway response to methacholine in patients with mild asthma. The possibility of a significant influence of pro-inflammatory stimuli on recumbency-induced changes in bronchomotor tone in more severe patients or if the stimulus is repeated should be further assessed.
在7名患有稳定轻度哮喘的非吸烟受试者（3名男性，4名女性）中记录了过敏原激发对卧位引起的气道对乙酰甲胆碱反应性变化的影响。
所有受试者在过敏原激发前和激发后24小时（上午8点至12点）仰卧4小时，该过敏原激发引发了双重哮喘反应。每小时测量一次仰卧位的第一秒用力呼气量（FEV1），并在每个4小时时间段前后在坐位进行乙酰甲胆碱激发试验。在研究前或研究期间，没有人使用支气管抗炎药物。
在最后一次吸入过敏原后1小时内，FEV1的平均最大下降（±标准误）为31.0±1.1%，在2至8小时后为27.5±4.9%。仰卧前/仰卧后时段的FEV1（预计值%±标准误）在基线或过敏原激发后时段均无变化，分别为89.3±2.7/88.3±5.1和86.6±4.2/87.4±5.7。仰卧前/仰卧后乙酰甲胆碱的激发浓度（PC20）略有降低，但未达到统计学意义（P>.05），平均PC20（mg/mL）为0.83±1.44/0.52±1.46（过敏原激发前时段）；0.55±1.44/0.39±1.37（过敏原激发后时段）。两个时段之间的PC20变化（基线/时段后）无差异（P>.05）。PC20变化与对过敏原的迟发性哮喘反应程度或过敏原激发后气道反应性增加无关。
我们得出结论，急性过敏原激发不会显著增加轻度哮喘患者卧位引起的气道对乙酰甲胆碱反应性的变化。对于更严重的患者，或者如果刺激重复，促炎刺激对卧位引起的支气管运动张力变化的显著影响的可能性应进一步评估。
