Hammo A H, Weinberger M M
University of Iowa Hospitals & Clinics, Iowa City, USA.
Ann Allergy Asthma Immunol. 1999 Jun;82(6):574-8. doi: 10.1016/S1081-1206(10)63169-9.
Exercise-induced asthma is common and generally responds well to an inhaled beta2 agonist.
We examined the physiologic changes in airflow and gas exchange that occurred during standardized treadmill exercise in patients previously diagnosed with exercise-induced asthma whose histories appeared atypical or where conventional treatment, including an inhaled beta2 agonist, was ineffective.
During a 1-year period 32 patients, aged 8 to 18, met these criteria. All had been previously diagnosed as having exercise-induced asthma. Exercise consisted of treadmill running at a time when the patients had received no inhaled beta2 agonist, cromolyn, or nedocromil for at least 4 hours. Spirometry was done before and at 2, 5, 10, and 15 minutes after exercise; oxygen saturation was monitored by pulse oximetry; and end-tidal CO2 was monitored with nasal cannula.
Despite their previous diagnoses of exercise-induced asthma, 11 patients who described chest tightness during exercise had decreases in FEV1 less than 15% with all but one of those less than 10% (mean decrease 5.6%) but demonstrated decreases in end-tidal CO2 greater than in all of the other 21 patients (mean 23.2 versus 9.8%, P < .01). Only 4 patients had unequivocal evidence for bronchospasm with cough and wheezing accompanying chest tightness in association with decreases in FEV1 from 18 to 22%. Seventeen patients had neither their symptoms reproduced nor physiologic abnormalities.
These data show that chest discomfort perceived as dyspnea during vigorous exercise may be associated with hypocapnia from hyperventilation without bronchospasm in children and adolescents previously misdiagnosed and treated as having exercise-induced asthma.
运动诱发性哮喘很常见，通常对吸入性β2激动剂反应良好。
我们研究了在标准化跑步机运动期间，先前被诊断为运动诱发性哮喘但病史不典型或包括吸入性β2激动剂在内的传统治疗无效的患者气流和气体交换的生理变化。
在1年期间，32名年龄在8至18岁的患者符合这些标准。所有患者先前均被诊断为运动诱发性哮喘。运动包括在患者至少4小时未接受吸入性β2激动剂、色甘酸钠或奈多罗米的情况下进行跑步机跑步。在运动前以及运动后2、5、10和15分钟进行肺活量测定；通过脉搏血氧饱和度仪监测血氧饱和度；并用鼻导管监测呼气末二氧化碳。
尽管先前诊断为运动诱发性哮喘，但11名在运动期间描述有胸部紧绷感的患者，其第一秒用力呼气量（FEV1）下降小于15%，除1名患者外其余均小于10%（平均下降5.6%），但呼气末二氧化碳下降幅度大于其他21名患者（分别为23.2%和9.8%，P<.01）。只有4名患者有明确的支气管痉挛证据，伴有咳嗽、喘息及胸部紧绷感，同时FEV1下降18%至22%。17名患者既没有再现症状，也没有生理异常。
这些数据表明，在先前被误诊并当作运动诱发性哮喘治疗的儿童和青少年中，剧烈运动期间被感知为呼吸困难的胸部不适可能与无支气管痉挛的过度通气引起的低碳酸血症有关。
