Cardiorespiratory Research Laboratory, Department of Medicine, McMaster University, Hamilton, Ontario, Canada.
Ann Allergy Asthma Immunol. 2013 May;110(5):359-63. doi: 10.1016/j.anai.2013.02.014. Epub 2013 Mar 19.
The effect of particle size on methacholine provocation concentration causing a decrease in forced expiratory volume of 1 second (FEV1) of 20% (PC20) is debatable.
To evaluate the functional effects of 3 different particle size nebulizers on methacholine PC20.
Participants were randomly assigned to have 3 methacholine challenges on 3 separate days. Nebulizer mass median aerodynamic diameter (MMAD) was provided by manufacturers. The Wright nebulizer (MMAD, 1.0 μm), Aeroneb (MMAD, 3 μm), and Aeroneb (MMAD, 5 μm) were calibrated, and the nebulizer outputs were calculated to administer 0.26 mL of methacholine over 120, 112, and 83 seconds, respectively. After each inhalation, spirometry was performed and the test was terminated when the PC20 was achieved.
Eight nonsmoking patients with mild asthma (4 male and 4 female) completed the study. The mean (SD) age was 25 (13.9) years, and the mean (SD) baseline FEV1 was 88% (11.3%). Patients using the Aeroneb (MMAD, 5 μm) nebulizer had the lowest PC20 (bronchoconstricted at lowest methacholine concentration), with a PC20 geometric mean of 0.62 mg/mL compared with patients using the Aeroneb (MMAD, 3.0 μm), who had a PC20 of 1.76 mg/mL, and patients using the Wright nebulizer (MMAD, 1.0 μm), who had a PC20 of 6.32 mg/mL. There was a significant difference in PC20 across all particle sizes (P < .001). The pairwise differences revealed a P < .001 between 3 μm and 1 μm and between 5 μm and 1 μm and a P = .008 between 5 μm and 3 μm.
Our results reveal a variability in methacholine PC20 using 3 different nebulizers, despite adjusting the nebulizers' outputs. Our results are consistent with the previous reports, which recommended using larger particle size nebulizers in the assessment of airway hyperresponsiveness in asthma.
clinicaltrials.gov Identifier: NCT00529477.
关于粒径对乙酰甲胆碱激发浓度导致一秒用力呼气容积（FEV1）下降 20%（PC20）的影响存在争议。
评估 3 种不同粒径雾化器对乙酰甲胆碱 PC20 的功能影响。
参与者被随机分配在 3 个不同的日子接受 3 次乙酰甲胆碱挑战。制造商提供雾化器质量中值空气动力学直径（MMAD）。对 Wright 雾化器（MMAD，1.0μm）、Aeroneb（MMAD，3μm）和 Aeroneb（MMAD，5μm）进行校准，并计算出每个雾化器的输出量，以便在 120、112 和 83 秒内分别输送 0.26 毫升乙酰甲胆碱。每次吸入后进行肺活量测定，当达到 PC20 时停止试验。
8 名非吸烟轻度哮喘患者（4 名男性和 4 名女性）完成了研究。平均（标准差）年龄为 25（13.9）岁，平均（标准差）基础 FEV1 为 88%（11.3%）。使用 Aeroneb（MMAD，5μm）雾化器的患者 PC20 最低（支气管收缩的最低乙酰甲胆碱浓度最低），其 PC20 几何平均值为 0.62mg/mL，而使用 Aeroneb（MMAD，3.0μm）的患者 PC20 为 1.76mg/mL，使用 Wright 雾化器（MMAD，1.0μm）的患者 PC20 为 6.32mg/mL。所有粒径的 PC20 均有显著差异（P<.001）。两两比较显示，3μm 和 1μm 之间（P<.001）以及 5μm 和 1μm 之间（P<.001）存在差异，而 5μm 和 3μm 之间（P=.008）存在差异。
尽管调整了雾化器的输出量，但我们的结果显示使用 3 种不同的雾化器时，乙酰甲胆碱 PC20 存在差异。我们的结果与先前的报告一致，即建议在评估哮喘的气道高反应性时使用较大粒径的雾化器。
clinicaltrials.gov 标识符：NCT00529477。
