Malo J L, L'Archevêque J, Ghezzo H, Cartier A
Department of Chest Medicine, Hôpital du Sacré-Coeur, Montreal, Canada.
Chest. 1995 May;107(5):1370-4. doi: 10.1378/chest.107.5.1370.
The aim of this work was to compare the response to an inhaled beta 2-adrenergic agent in two situations: (1) spontaneous airway obstruction in asthmatic subjects who had withheld treatment with the medication for more than 12 hs; and (2) after methacholine-induced airway obstruction once airway caliber had recovered to the premethacholine test value.
Sixteen asthmatic subjects who showed a 20% or more improvement in FEV1 after inhaled beta 2-adrenergic agent (B2) (salbutamol, 200 micrograms) entered a double-blind crossover randomized trial in which the following tests were carried out: (1) FEV1 response after inhaling a placebo or active B2; (2) FEV1 response after inhaling a placebo or active B2 after a methacholine test that had induced a 20% or more reduction in FEV1, once FEV1 had recovered to the premethacholine value after inhaling salbutamol in an open fashion.
As expected, the mean percent improvement in FEV1 in the spontaneous airway obstruction situation was 21.7 +/- 8.5% after inhaling the active B2 and 2.2 +/- 1.8% after placebo B2 (p < 0.001). Following recovery after methacholine challenge, the FEV1 was slightly superior (mean difference of 146 mL) to the premethacholine value before inhaling the active or placebo B2. In this situation, the percent improvement in FEV1 after inhaling the active B2 was only 7.5 +/- 4.4% and not significantly different from after inhaling placebo B2 (4.9 +/- 5.4%). Consequently, the end FEV1 value after inhaling active B2 was significantly higher in a situation of spontaneous airway obstruction than after methacholine-induced airway obstruction (mean difference = 110 mL; p = 0.02).
After a methacholine test, the reversibility of an inhaled beta 2 agent is not significantly different from a placebo and is less satisfactory than in a situation of spontaneous airway obstruction. The mechanism for this needs to be explored but it is not secondary to persisting airway obstruction.
本研究旨在比较在两种情况下吸入β2肾上腺素能药物的反应：（1）哮喘患者在停用该药物治疗超过12小时后的自发性气道阻塞；（2）在乙酰甲胆碱诱导的气道阻塞后，气道口径恢复到乙酰甲胆碱试验前值时。
16名哮喘患者在吸入β2肾上腺素能药物（B2）（沙丁胺醇，200微克）后FEV1改善20%或更多，进入双盲交叉随机试验，进行以下测试：（1）吸入安慰剂或活性B2后的FEV1反应；（2）在乙酰甲胆碱试验使FEV1降低20%或更多后，吸入安慰剂或活性B2后的FEV1反应，在以开放方式吸入沙丁胺醇后FEV1恢复到乙酰甲胆碱试验前值时进行。
正如预期的那样，在自发性气道阻塞情况下，吸入活性B2后FEV1的平均改善百分比为21.7±8.5%，吸入安慰剂B2后为2.2±1.8%（p<0.001）。乙酰甲胆碱激发后恢复后，FEV1略高于吸入活性或安慰剂B2前的乙酰甲胆碱试验前值（平均差异为146毫升）。在这种情况下，吸入活性B2后FEV1的改善百分比仅为7.5±4.4%，与吸入安慰剂B2后（4.9±5.4%）无显著差异。因此，在自发性气道阻塞情况下吸入活性B2后的最终FEV1值显著高于乙酰甲胆碱诱导的气道阻塞后（平均差异=110毫升；p=0.02）。
乙酰甲胆碱试验后，吸入β2药物的可逆性与安慰剂无显著差异，且不如自发性气道阻塞情况令人满意。对此的机制需要进行探索，但并非继发于持续性气道阻塞。
