Lougheed M Diane, Fisher Thomas, O'Donnell Denis E
Asthma Research Unit, Department of Medicine, Queen's University, 102 Stuart St, Kingston, ON, K7L 2V6, Canada.
Chest. 2006 Oct;130(4):1072-81. doi: 10.1378/chest.130.4.1072.
The objective of this study was to examine the relationship between respiratory symptom intensity and quality and dynamic lung hyperinflation (DH) during induced bronchoconstriction in asthma.
Subjects with asthma (n = 116) underwent baseline spirometry and lung volume measurement followed by high-dose methacholine challenge testing (MCT) [maximum decrease in FEV(1) of 50% from baseline]. Dyspnea intensity (Borg scale) was measured after each dose of methacholine. Qualitative descriptors of breathlessness and functional residual capacity (FRC) were measured at the doses nearest to the provocative concentration of methacholine causing a 20% fall in FEV (PC(20)) and at the highest dose of methacholine (maximum response).
FEV(1) decreased by 24.7 +/- 0.7% (mean +/- SEM) at the dose nearest to PC(20) and by 46.1 +/- 1.1% at maximum response. Inspiratory capacity decreased by 0.62 +/- 0.04 L at the dose nearest to PC(20) and 1.06 +/- 0.06 L at maximum response. The descriptor clusters "inspiratory difficulty," "chest tightness," "unsatisfied inspiration," and "work" were selected at the dose nearest to PC(20) but were more frequently selected at maximum response (p < 0.0001). Individuals who reported chest tightness at maximum response had greater airflow obstruction and higher FRC (percentage of predicted) than those who did not report chest tightness.
Four dominant qualities of dyspnea in asthma (inspiratory difficulty, chest tightness, unsatisfied inspiration, and work) were reported early in the course of MCT and evolved in parallel, becoming more prevalent at maximum response. Significant DH accompanied even mild bronchoconstriction during MCT in asthma, making it difficult to separate mechanisms of chest tightness from other dominant respiratory sensations.
本研究旨在探讨哮喘患者在诱发支气管收缩过程中呼吸症状的强度、性质与动态肺过度充气（DH）之间的关系。
116例哮喘患者接受基线肺量计检查和肺容积测量，随后进行高剂量乙酰甲胆碱激发试验（MCT）[第一秒用力呼气容积（FEV₁）自基线下降50%]。每次给予乙酰甲胆碱后测量呼吸困难强度（Borg量表）。在最接近使FEV下降20%的乙酰甲胆碱激发浓度（PC₂₀）的剂量以及乙酰甲胆碱最高剂量（最大反应）时，测量呼吸急促的定性描述指标和功能残气量（FRC）。
在最接近PC₂₀的剂量时，FEV₁下降了24.7±0.7%（均值±标准误），在最大反应时下降了46.1±1.1%。在最接近PC₂₀的剂量时，吸气容量下降了0.62±0.04L，在最大反应时下降了1.06±0.06L。在最接近PC₂₀的剂量时选择了“吸气困难”“胸闷”“吸气未满足感”和“做功”等描述指标簇，但在最大反应时更频繁地被选择（p<0.0001）。在最大反应时报告有胸闷的个体比未报告胸闷的个体有更严重的气流阻塞和更高的FRC（预测值百分比）。
在MCT过程早期就报告了哮喘患者呼吸困难的四种主要性质（吸气困难、胸闷、吸气未满足感和做功），且它们平行演变，在最大反应时更普遍。在哮喘患者MCT期间，即使是轻度支气管收缩也伴有显著的DH，使得难以将胸闷机制与其他主要呼吸感觉的机制区分开来。
