Miller Albert, Palecki Agnes
Pulmonary Division, Department of Medicine, St Vincent Catholic Medical Centers-Queens Division, Mary Immaculate Hospital, Jamaica, NY 11432, USA.
Respir Med. 2007 Feb;101(2):272-6. doi: 10.1016/j.rmed.2006.05.008. Epub 2006 Jun 22.
Patients with asthma have intermittent or persistent airflow obstruction, most often manifested spirometrically by reduced forced expiratory volume in 1s (FEV(1)) and FEV(1)/vital capacity (VC) ratio. In some patients, the VC may be reduced by air trapping, with an increase in functional residual capacity (FRC) and residual volume (RV) (pseudorestriction). We have reported 12 asthmatic patients with reduced VC and no increase in RV, i.e., a true restrictive impairment [Gill et al. True restrictive impairment in bronchial asthma. Am J Respir Crit Care Med 1999:159:A652].
To confirm previous observations of true restrictive impairment (not attributable to air trapping) in patients with asthma, and to estimate its frequency in an asthmatic population.
Review of pulmonary function tests and clinical records of all post-pubertal patients diagnosed as asthma between January 2000 and September 2003 in a 184 bed inner city teaching hospital in Jamaica, Queens, New York. The clinical diagnosis of asthma was accepted when one or more of the following pulmonary function criteria were met: Positive bronchodilator response (BD), positive methacholine, repeated variability in spirometric values. Restriction was defined as decrease in total lung capacity (TLC) or decrease in VC with no increase in functional residual capacity (FRC) plus normal or high FEV(1)/FVC ratio. Patients with any clinical finding consistent with restriction, including a decreased diffusing capacity (DL) or obesity (BMI >30) were excluded.
A total of 100 of 413 (24%) patients with asthma had restriction; 21 of these met all exclusions (including DL and BMI) and 11 (of 46) patients with an increased BMI and normal DL normalized their FVC on BD therapy, demonstrating that their pre-BD restrictive impairment could not be attributed to obesity. Plethysmographic FRC was measured in 81 of the 100 patients with restriction and was increased in only seven.
True restrictive impairment was noted in at least 32 of 413 asthmatics (8%), consistent with previous observations in asthma and reactive airways dysfunction syndrome. This finding is not widely recognized and should not preclude the diagnosis of asthma, BD testing or appropriate therapy for asthma.
哮喘患者存在间歇性或持续性气流受限，多数情况下通过肺量计检查表现为1秒用力呼气容积（FEV₁）降低以及FEV₁/肺活量（VC）比值降低。在一些患者中，VC可能因气体潴留而降低，同时功能残气量（FRC）和残气量（RV）增加（假性受限）。我们曾报道过12例VC降低且RV未增加的哮喘患者，即真正的限制性损害[吉尔等人。支气管哮喘中的真正限制性损害。《美国呼吸与危重症医学杂志》1999年：159：A652]。
证实先前关于哮喘患者存在真正的限制性损害（并非由气体潴留所致）的观察结果，并估计其在哮喘人群中的发生率。
回顾纽约皇后区牙买加市一家拥有184张床位的市中心教学医院在2000年1月至2003年9月期间诊断为哮喘的所有青春期后患者的肺功能检查和临床记录。当满足以下一项或多项肺功能标准时，接受哮喘的临床诊断：支气管扩张剂反应阳性（BD）、乙酰甲胆碱激发试验阳性、肺量计值反复波动。限制性损害定义为肺总量（TLC）降低或VC降低且功能残气量（FRC）未增加，同时FEV₁/FVC比值正常或升高。排除任何与限制性损害一致的临床发现的患者，包括弥散功能降低（DL）或肥胖（体重指数>30）。
413例哮喘患者中有共100例（24%）存在限制性损害；其中21例符合所有排除标准（包括DL和体重指数），46例体重指数增加且DL正常的患者中有11例在接受BD治疗后FVC恢复正常，表明其BD治疗前的限制性损害并非由肥胖所致。在100例存在限制性损害的患者中，81例进行了体描法FRC测量，其中仅7例FRC增加。
413例哮喘患者中至少有32例（8%）存在真正的限制性损害，这与先前在哮喘和反应性气道功能障碍综合征中的观察结果一致。这一发现尚未得到广泛认可，且不应排除哮喘的诊断、BD检测或哮喘的适当治疗。
