Rao Devika R, Gaffin Jonathan M, Baxi Sachin N, Sheehan William J, Hoffman Elaine B, Phipatanakul Wanda
Division of Respiratory Diseases, Boston Children's Hospital, 300 Longwood Ave., Boston, MA 02215, USA.
J Asthma. 2012 Aug;49(6):586-92. doi: 10.3109/02770903.2012.690481. Epub 2012 Jun 28.
The forced expiratory volume in 1 second (FEV(1)) felt to be an objective measure of airway obstruction is often normal in asthmatic children. The forced expiratory flow between 25% and 75% of vital capacity (FEF(25-75)) reflects small airway patency and has been found to be reduced in children with asthma. The aim of this study was to determine whether FEF(25-75) is associated with increased childhood asthma severity and morbidity in the setting of a normal FEV(1), and to determine whether bronchodilator responsiveness (BDR) as defined by FEF(25-75) identifies more childhood asthmatics than does BDR defined by FEV(1).
The Boston Children's Hospital Pulmonary Function Test database was queried and the most recent spirometry result was retrieved for 744 children diagnosed with asthma between 10 and 18 years of age between October 2000 and October 2010. Electronic medical records in the 1 year prior and the 1 year following the date of spirometry were examined for asthma severity (mild, moderate, or severe) and morbidity outcomes for the three age, race, and gender-matched subgroups: Group A (n = 35) had a normal FEV(1), FEV(1)/forced vital capacity (FVC), and FEF(25-75); Group B (n = 36) had solely a diminished FEV(1)/FVC; and Group C (n = 37) had a normal FEV(1), low FEV(1)/FVC, and low FEF(25-75). Morbidity outcomes analyzed included the presence of hospitalization, emergency department visit, intensive care unit admission, asthma exacerbation, and systemic steroid use.
Subjects with a low FEF(25-75) (Group C) had nearly 3 times the odds ratio (OR) (OR = 2.8, p < .01) of systemic corticosteroid use and 6 times the OR of asthma exacerbations (OR = 6.3, p > .01) compared with those who had normal spirometry (Group A). Using FEF(25-75) to define BDR identified 53% more subjects with asthma than did using a definition based on FEV(1).
A low FEF(25-75) in the setting of a normal FEV(1) is associated with increased asthma severity, systemic steroid use, and asthma exacerbations in children. In addition, using the percent change in FEF(25-75) from baseline may be helpful in identifying BDR in asthmatic children with a normal FEV(1).
1秒用力呼气容积（FEV₁）常被视为气道阻塞的客观指标，但在哮喘儿童中往往正常。肺活量25%至75%之间的用力呼气流量（FEF₂₅₋₇₅）反映小气道通畅情况，已发现哮喘儿童的该指标降低。本研究的目的是确定在FEV₁正常的情况下，FEF₂₅₋₇₅是否与儿童哮喘严重程度增加及发病率升高相关，以及确定以FEF₂₅₋₇₅定义的支气管舒张反应性（BDR）是否比以FEV₁定义的BDR能识别出更多的儿童哮喘患者。
查询波士顿儿童医院肺功能测试数据库，获取2000年10月至2010年10月期间诊断为哮喘的744名10至18岁儿童的最新肺量计检查结果。检查肺量计检查日期前1年和后1年的电子病历，了解三个年龄、种族和性别匹配亚组的哮喘严重程度（轻度、中度或重度）和发病情况：A组（n = 35）的FEV₁、FEV₁/用力肺活量（FVC）和FEF₂₅₋₇₅正常；B组（n = 36）仅FEV₁/FVC降低；C组（n = 37）的FEV₁正常、FEV₁/FVC低且FEF₂₅₋₇₅低。分析的发病情况包括住院、急诊就诊就诊、重症监护病房入院、哮喘发作和全身使用类固醇。
与肺量计检查正常的受试者（A组）相比，FEF₂₅₋₇₅低的受试者（C组）全身使用皮质类固醇的比值比（OR）近3倍（OR = 2.8，p <.01），哮喘发作的OR为6倍（OR = 6.3，p >.01）。用FEF₂₅₋₇₅定义BDR识别出的哮喘患者比用基于FEV₁定义的多53%。
在FEV₁正常的情况下，FEF₂₅₋₇₅低与儿童哮喘严重程度增加、全身使用类固醇及哮喘发作增多相关。此外，使用FEF₂₅₋₇₅相对于基线的变化百分比可能有助于识别FEV₁正常的哮喘儿童的BDR。
