Holguin Fernando, Cribbs Sushma, Fitzpatrick Anne M, Ingram Roland H, Jackson Andrew C
Asthma Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
J Asthma. 2010 Feb;47(1):55-60. doi: 10.3109/02770900903318330.
Asthma is characterized by the loss of a deep breath (DB)-induced bronchodilation and bronchoprotection. Obesity causes lung restriction and increases airway resistance, which may further worsen the capacity of a DB to induce bronchodilation; however, whether increasing BMI impairs the bronchodilatory response to a DB in asthmatics is unknown.
The population consisted of 99 subjects, 87 with moderate to severe persistent asthma and 12 obese control subjects. Using transfer impedance we derived airway resistance (Raw). Participants breathed for 1 minute and took a slow DB followed by passive exhalation to functional residual capacity (FRC) and tidal breathing for another minute.
After a DB, obese asthmatics had the largest percent increase in Raw (median 9.8% interquartile range [IQR] 3.1-15.1), compared with overweight (6.5% IQR -1.3, 12.1) and lean (0.7% IQR -3, 7.9) asthmatics and obese controls (2.5% IQR -.6, 11) (p for trend = 0.008). The association between the percent increase in Raw after a DB and BMI as a continuous variable was significant (p = 0.02).
In obese, moderate to severe and poorly controlled asthmatics, a DB results in increased Raw. This phenomenon was not observed in leaner asthmatics of similar severity or in obese control subjects.
哮喘的特征是深呼吸（DB）诱导的支气管舒张和支气管保护作用丧失。肥胖会导致肺受限并增加气道阻力，这可能会进一步加重DB诱导支气管舒张的能力；然而，体重指数（BMI）增加是否会损害哮喘患者对DB的支气管舒张反应尚不清楚。
研究人群包括99名受试者，其中87名患有中度至重度持续性哮喘，12名肥胖对照受试者。使用传输阻抗我们得出气道阻力（Raw）。参与者呼吸1分钟，进行一次缓慢的DB，然后被动呼气至功能残气量（FRC），再进行1分钟的潮气呼吸。
与超重（6.5%，四分位间距[IQR]-1.3，12.1）、瘦（0.7%，IQR-3，7.9）哮喘患者和肥胖对照者（2.5%，IQR-.6，11）相比，肥胖哮喘患者在DB后Raw的增加百分比最大（中位数9.8%，IQR 3.1-15.1）（趋势p=0.008）。DB后Raw增加百分比与作为连续变量的BMI之间的关联具有显著性（p=0.02）。
在肥胖、中度至重度且控制不佳的哮喘患者中，DB会导致Raw增加。在类似严重程度的较瘦哮喘患者或肥胖对照受试者中未观察到这种现象。
