Allen Nathan D, Davis Beth E, Hurst Thomas S, Cockcroft Donald W
Royal University Hospital, Department of Physiology, Division of Respirology, Critical Care and Sleep Medicine, 103 Hospital Dr, Ellis Hall, Room 551, Saskatoon, SK, S7N 0W8 Canada.
Chest. 2005 Dec;128(6):4018-23. doi: 10.1378/chest.128.6.4018.
Two bronchoprovocation methods are widely used. Compared to the tidal breathing method, the dosimeter method delivers approximately half the dose and involves five deep inhalations. Both the lower dose and the bronchoprotective deep inhalations contribute to the lesser airway response of the dosimeter.
To determine the relative role of dose and deep inspiration in the difference between the two methods.
Subjects with asthma (n = 24) underwent three methacholine challenges: a dosimeter challenge, a 2-min tidal breathing challenge (twice the dose), and a modified 2-min tidal breathing challenge (twice the dose plus five deep inhalations).
The dosimeter method produced a nonsignificantly lower response than the modified tidal breathing method (p = 0.14). Both deep inhalation methods produced significantly less response than did the standard tidal breathing method (p = 0.011). In the 12 subjects with the most mild airway hyperresponsiveness (AHR), the differences between the deep inhalation method and the tidal breathing method were greater (p = 0.007). By contrast, deep inhalations produced no effect in the 12 subjects with greater AHR; the two tidal breathing methods produced identical results, while the dosimeter produced less response than either (p = 0.033). Six current asthmatics with mild airway responsiveness (tidal breathing method) had negative dosimeter methacholine challenge results.
In subjects with moderate airway responsiveness, the difference between the methods is due to the difference in dose, whereas in subjects with mild AHR, deep inhalations had a large effect overwhelming the dose effect and producing false-negative methacholine challenge results in 25% of the subjects.
两种支气管激发方法被广泛使用。与潮气呼吸法相比，剂量计法输送的剂量约为一半，且需要五次深呼吸。较低的剂量和具有支气管保护作用的深呼吸都导致剂量计法的气道反应较小。
确定剂量和深呼吸在两种方法差异中的相对作用。
哮喘患者（n = 24）接受三次乙酰甲胆碱激发试验：剂量计激发试验、2分钟潮气呼吸激发试验（剂量加倍）和改良的2分钟潮气呼吸激发试验（剂量加倍加五次深呼吸）。
剂量计法产生的反应略低于改良潮气呼吸法（p = 0.14）。两种深呼吸方法产生的反应均明显低于标准潮气呼吸法（p = 0.011）。在12例气道高反应性（AHR）最轻微的受试者中，深呼吸法与潮气呼吸法之间的差异更大（p = 0.007）。相比之下，深呼吸对12例AHR较高的受试者没有影响；两种潮气呼吸法产生相同的结果，而剂量计法产生的反应低于两者（p = 0.033）。六例当前哮喘且气道反应性轻度（潮气呼吸法）的患者剂量计乙酰甲胆碱激发试验结果为阴性。
在气道反应性中等的受试者中，方法之间的差异是由于剂量差异，而在轻度AHR的受试者中，深呼吸的影响很大，超过了剂量效应，并导致25%的受试者乙酰甲胆碱激发试验结果出现假阴性。
