脉冲振荡法测定呼吸阻抗评估哮喘患者运动反应

Respiratory impedance assessed with impulse oscillometry in measuring exercise response of asthmatic patients

目的 应用脉冲振荡法测定运动激发前后健康志愿者和哮喘患者呼吸阻抗的改变 ,探讨运动激发和脉冲振荡法在支气管哮喘诊断中的意义。方法 健康对照组和哮喘组各 14例 ,应用脉冲振荡仪测定呼吸阻抗基础值 ,随后进行踏车运动激发试验 ,夹鼻经口呼吸室内空气 ,递增负荷 ,在 3～ 4min内使心率达到最大预计值 90 %并维持 6min ,运动结束后l、5、10、15和 2 0min重复测定呼吸阻抗。结果 哮喘患者运动后周围气道阻力比中央气道阻力明显增高 ,共振频率右移。呼吸总阻抗在第 5～ 10min达到峰值。哮喘患者R5 -R2 0变化值均≥ 0 .0 32kPa/L·s(对照组均值与 2个标准差之和 ) ,对照组均低于该值。6 4.3 %患者呼吸总阻抗变化值≥ 0 .12 7kPa/L·s(对照组均值与 2个标准差之和 ) ,对照组均低于该值。71.4%患者X5变化率≥ 41% (对照组均值与 2个标准差之和 ) ,对照组均低于该变化率。 5 7.1%患者运动后在潮气量 -呼吸总阻抗图中出现气体陷闭环 ,而对照组均无该变化。结论 运动激发前后应用脉冲振荡法测定呼吸阻抗能反映哮喘患者运动激发前后气道阻力的变化 ,且不需用力呼气 ,比较简便。运动试验作为临床诊断哮喘的方法和评估药物疗效的手段 。

Objective Approximately 80%～90% of asthma sufferers experience exercise induced bronchoconstriction. The response is assessed with spirometry (FEV 1) traditionally. Because the patients usually have shortness of breath after exercise challenge, the measurement with FEV 1 may be not accurate. Impulse oscillometry (IOS) is a new technique for measuring respiratory impedance that does not require maximal inspiration and force expiration. Respiratory impedance was assessed with IOS for pathophysiology of exerciseinduced asthma. Methods Respiratory impedance measured with IOS (MasterScreen, Jeager, Germany) in 14 healthy volunteers and 14 asthmatics was as baseline value at first. The procedure of exercise challenge with an ergometer (Corival 300 Gould Co) increased heart rate to 90% of predicted maximum values in 3～4 min and maintained for 6 min. After the challenge, measurement with IOS was made immediately at 5min intervals for 5 times. Results The maximal increase of respiratory impedance occurred at 5～10 min after exercise and the increment magnitude of peripheral resistance ( 99.6 %) was more than that of central resistance ( 13.5 %) in asthmatics. During challenge,the subject's nose was clipped breathing room air through mouth.After challenge, R5, R5-R20, Zrespir, resonance frequency (Fres) and X5 from patients changed significantly. The increment of R5-R20 from all asthmatics≥ 0.032 kPa/L·s(2s beyond the mean response of nonasthmatics). The change ratio of X5 from 71.4 % asthmatics ≥41% (2s beyond the mean response of nonasthmatics). Air trapping was expressed in V TZrespir graph in 57.1 % patients. Conclusion The main site of airflow obstruction was in small airways in asthmatics after exercise challenge. The general acceptance of IOS method was good among the asthmatic patients. The airway response of exercise challenge may be assessed more accurately with IOS,which dose not require a maximal inspiration and forced expiration.