Prieto Luis, Ferrer Ana, Domenech Juan, Pérez-Francés Carmen
Sección de Alergología, Hospital Universitario Dr Peset, Valencia, Spain.
Ann Allergy Asthma Immunol. 2006 Aug;97(2):175-81. doi: 10.1016/S1081-1206(10)60009-9.
Recent data suggest that the tidal breathing method may produce methacholine provocation concentration that caused a decrease in forced expiratory volume in 1 second of 20% (PC20) values significantly lower than the dosimeter method; however, the effect of the challenge method on the shape of the concentration-response curve has not been investigated.
To determine the effect of the challenge method on sensitivity, reactivity, and maximal response to methacholine.
We measured airway responsiveness to methacholine using dosimeter and tidal breathing methods in 30 individuals with suspected asthma. Concentration-response curves were characterized by their PC20 (sensitivity), slope (reactivity), and, if possible, level of plateau.
Dosimeter PC20 values were significantly higher than tidal breathing values (geometric mean, 8.9 and 5.2 mg/mL, respectively); the mean difference in PC20 values obtained using each method was 0.78 doubling concentrations (P = .01). The mean slopes were 22.7%/log mg/mL using the tidal breathing method and 24.9%/log mg/mL using the dosimeter method; the mean difference in the slopes obtained using each method was -2.17%/log mg/mL (P = .18). In 10 individuals who showed a plateau with the 2 methacholine challenge tests, the mean level of plateau was 19.8% using the tidal breathing method and 19.5% using the dosimeter method; the mean difference in the plateau values obtained with each method was 0.3% (P = .87).
Although the tidal breathing method produces methacholine PC20 values significantly lower than the dosimeter method, both methods provide similar values for slope and level of plateau. These results suggest that the technical factors that affect methacholine sensitivity and the shape of the curve are different.
近期数据表明，潮气呼吸法所产生的乙酰甲胆碱激发浓度致使1秒用力呼气量降低20%（PC20）的值显著低于剂量仪法；然而，激发方法对浓度-反应曲线形状的影响尚未得到研究。
确定激发方法对乙酰甲胆碱敏感性、反应性及最大反应的影响。
我们对30名疑似哮喘患者使用剂量仪法和潮气呼吸法测量气道对乙酰甲胆碱的反应性。浓度-反应曲线通过其PC20（敏感性）、斜率（反应性）以及（若可能）平台水平来表征。
剂量仪法的PC20值显著高于潮气呼吸法的值（几何平均数分别为8.9和5.2毫克/毫升）；使用每种方法获得的PC20值的平均差异为0.78倍浓度（P = 0.01）。潮气呼吸法的平均斜率为22.7%/对数毫克/毫升，剂量仪法为24.9%/对数毫克/毫升；使用每种方法获得的斜率的平均差异为-2.17%/对数毫克/毫升（P = 0.18）。在10名在两次乙酰甲胆碱激发试验中出现平台的个体中，潮气呼吸法的平均平台水平为19.8%，剂量仪法为19.5%；使用每种方法获得的平台值的平均差异为0.3%（P = 0.87）。
尽管潮气呼吸法产生的乙酰甲胆碱PC20值显著低于剂量仪法，但两种方法在斜率和平台水平方面提供了相似的值。这些结果表明，影响乙酰甲胆碱敏感性和曲线形状的技术因素是不同的。
