The mechanism for symptomatic improvement after bronchial thermoplasty (BT) is unclear, since spirometry reveals little or no change. In this study, the effects of BT on airway resistance were examined using two independent techniques. Eighteen consecutive patients, with severe asthma (57.6 ± 14.2 years) were evaluated by spirometry and plethysmography at three time points: (i) baseline, (ii) left lung treated but right lung untreated and (iii) 6 weeks after both lungs were treated with BT. At each assessment, total and specific airway resistance (Raw, sRaw) were measured. High resolution CT scans were undertaken at the first two assessments, and measurements of lobar volume, airway volume and airway resistance were made. The Asthma Control Questionnaire (ACQ) was administered at each assessment. The baseline ACQ score was 3.5 ± 0.9, and improved progressively to 1.8 ± 1.2 (p < 0.01). At baseline, severe airflow obstruction was observed, FEV1 44.8 ± 13.7% predicted, together with gas trapping, and elevated Raw at 342 ± 173%predicted. Following BT, significant improvements in Raw and sRaw were observed, as well as a reduction in Residual Volume, increase in Vital Capacity and no change in FEV1. The change in Raw correlated with the change in ACQ (r = 0.56, p < 0.05). CT scans demonstrated reduced airway volume at baseline, which correlated with the increased Raw determined by plethysmography (p = − 0.536, p = < 0.05). Following BT, the airway volume increased in the treated lung, and this was accompanied by a significant reduction in CT-determined local airway resistance. Symptomatic improvement after BT is mediated by increased airway volume and reduced airway resistance.

中文翻译：

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支气管热成形术可降低气道阻力


支气管热成形术 (BT) 后症状改善的机制尚不清楚，因为肺活量测定显示很少或没有变化。在这项研究中，使用两种独立的技术检查了 BT 对气道阻力的影响。连续 18 名严重哮喘患者（57.6 ± 14.2 岁）在三个时间点通过肺活量测定和体积描记法进行评估：(i) 基线、(ii) 左肺接受治疗但右肺未接受治疗以及 (iii) 双肺接受治疗后 6 周与英国电信。每次评估时，都会测量总气道阻力和特定气道阻力（Raw、sRaw）。在前两次评估中进行了高分辨率 CT 扫描，并测量了肺叶体积、气道体积和气道阻力。每次评估时均进行哮喘控制问卷（ACQ）。基线 ACQ 评分为 3.5 ± 0.9，并逐渐提高至 1.8 ± 1.2 (p < 0.01)。在基线时，观察到严重的气流阻塞，FEV1 预计为 44.8 ± 13.7%，并伴有气体滞留，Raw 升高为预计的 342 ± 173%。 BT 后，观察到 Raw 和 sRaw 显着改善，残气量减少，肺活量增加，FEV1 没有变化。 Raw 的变化与 ACQ 的变化相关（r = 0.56，p < 0.05）。 CT 扫描显示基线时气道容积减少，这与体积描记法确定的 Raw 增加相关（p = − 0.536，p = < 0.05）。 BT 治疗后，治疗肺部的气道容积增加，同时 CT 确定的局部气道阻力显着降低。 BT 后症状的改善是通过增加气道容量和减少气道阻力来实现的。