[1] Capital Med Univ, Beijing Chao Yang Hosp, Dept Emergency Med, 8 Workers Stadium South Rd, Beijing 100020, Peoples R China
[2] Capital Med Univ, Beijing Shijitan Hosp, Dept Allergy, Beijing, Peoples R China
[3] Capital Med Univ, Beijing Chao Yang Hosp, Dept Resp & Crit Care Med, Beijing, Peoples R China