Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China.
Department of Pulmonary Function Test, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China.
Clinics (Sao Paulo). 2020 Oct 19;75:e1662. doi: 10.6061/clinics/2020/e1662. eCollection 2020.
To evaluate the quantitative changes and diagnostic performance of volumetric capnography (VCap) parameters in patients with cough variant asthma.
This cross-sectional study enrolled 31 patients with cough variant asthma and 30 patients with chronic cough without asthma between November 2010 and March 2012. VCap measurements were recorded at baseline, during the five steps of the histamine challenge, and after bronchodilation with salbutamol. They were then compared between the baseline and histamine challenge, and between the two groups. Receiver operating characteristic curve analysis was performed for different VCap measurements.
The slope of phase III (dc\dv3) and the ratio of phase III slope to phase II slope (SR23%) decreased from baseline upon challenge with 1.1 mg histamine in cough variant asthma patients but increased in patients with chronic cough without asthma. Additionally, the change upon challenge with 1.1 mg histamine in dc\dv3 from baseline (S6-S1dc\dv3) in cough variant asthma patients had the largest area under the curve (AUC) (0.814, 95% CI: 0.697-0.931; p<0.001). The AUC for change upon challenge with 1.1 mg histamine in SR23% from baseline was 0.755 (95%CI: 0.632-0.878; p<0.001). At a cutoff of 19.8, S6-S1 dc\dv3 had a sensitivity of 74.2% and specificity of 90.0% and at a cutoff of 40.7, S6-S1 SR23% had a sensitivity of 48.4% and specificity of 96.7%.
Patients with cough variant asthma exhibit distinct VCap responses for dead space parameters upon challenge with histamine in comparison to patients with chronic cough. VCap parameters like phase III slope and phase III/phase II slope ratio could be used to aid the diagnosis of cough variant asthma.
评估容积二氧化碳图（VCap）参数在咳嗽变异性哮喘患者中的定量变化和诊断性能。
本横断面研究纳入了 2010 年 11 月至 2012 年 3 月期间 31 例咳嗽变异性哮喘患者和 30 例无哮喘慢性咳嗽患者。在基础状态、组胺激发的五个阶段以及沙丁胺醇支气管扩张后记录 VCap 测量值。然后将其与基础状态和组胺激发进行比较，并在两组之间进行比较。对不同 VCap 测量值进行受试者工作特征曲线分析。
在咳嗽变异性哮喘患者中，第 III 相（dc\dv3）斜率和第 III 相斜率与第 II 相斜率的比值（SR23%）在 1.1mg 组胺激发后从基础值下降，但在无哮喘慢性咳嗽患者中增加。此外，咳嗽变异性哮喘患者在 1.1mg 组胺激发后基线时 dc\dv3 的变化（S6-S1dc\dv3）具有最大的曲线下面积（AUC）（0.814，95%CI：0.697-0.931；p<0.001）。SR23%从基线激发变化的 AUC 为 0.755（95%CI：0.632-0.878；p<0.001）。在截止值为 19.8 时，S6-S1 dc\dv3 的灵敏度为 74.2%，特异性为 90.0%，在截止值为 40.7 时，S6-S1 SR23%的灵敏度为 48.4%，特异性为 96.7%。
与慢性咳嗽患者相比，咳嗽变异性哮喘患者在接受组胺激发时表现出明显的 VCap 死腔参数反应。VCap 参数，如第 III 相斜率和第 III 相/第 II 相斜率比值，可用于辅助咳嗽变异性哮喘的诊断。
