Black Lauren D, Henderson Angela C, Atileh Haytham, Israel Elliot, Ingenito Edward P, Lutchen Kenneth R
Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA.
J Appl Physiol (1985). 2004 May;96(5):1808-14. doi: 10.1152/japplphysiol.01170.2003. Epub 2004 Feb 6.
Measures of airway resistance (Raw) during deep inspiration (DI) suggest that asthmatic subjects possess stiffer, more reactive airway smooth muscle. There is evidence that one can enhance airway reactivity in healthy lungs by prohibiting DI for an extended period. The present study had two goals. First, we determined whether the maximum dilation capacity of asthmatic subjects depended on the rate of the DI. Second, we investigated whether the enhanced reactivity in healthy humans might derive from additional mechanisms not present in asthmatic subjects. For the first goal, we tracked Raw in seven healthy and seven asthmatic subjects during a noncoached DI, a DI with a 5- to 10-s breath hold at total lung capacity, and a rapid DI. We found that the minimum resistance achieved at total lung capacity was independent of the manner in which the DI was performed. For the second goal, we tracked the rate of return of Raw after a DI as well as dynamic lung elastance before and after the DI, at baseline and after bronchial challenge. A drop in lung elastance post-DI would indicate reopening of lung regions and/or reduced heterogeneities. The data show that constricted healthy but not asthmatic subjects produce longer lasting residual dilation. Hence, a portion of the enhanced reactivity in a healthy subject's response to prohibition of DIs is likely due to airway closure and/or atelectasis that can be ablated with a DI. We conclude that preventing DIs does not ensure that healthy subjects will transition entirely to an asthmatic-like hyperreactive lung state.
深吸气（DI）期间气道阻力（Raw）的测量结果表明，哮喘患者的气道平滑肌更僵硬、反应性更强。有证据表明，长时间禁止深吸气可增强健康肺部的气道反应性。本研究有两个目标。首先，我们确定哮喘患者的最大扩张能力是否取决于深吸气的速率。其次，我们研究了健康人增强的反应性是否可能源于哮喘患者不存在的其他机制。对于第一个目标，我们在无指导的深吸气、在肺总量时屏气5至10秒的深吸气以及快速深吸气过程中，对7名健康受试者和7名哮喘患者的气道阻力进行了跟踪。我们发现，在肺总量时达到的最小阻力与深吸气的执行方式无关。对于第二个目标，我们在基线和支气管激发后，跟踪了深吸气后气道阻力的恢复速率以及深吸气前后的动态肺弹性。深吸气后肺弹性下降表明肺区域重新开放和/或异质性降低。数据显示，健康但非哮喘受试者出现收缩时会产生持续时间更长的残余扩张。因此，健康受试者对禁止深吸气反应中增强的反应性部分可能是由于气道关闭和/或肺不张，而深吸气可以消除这些情况。我们得出结论，防止深吸气并不能确保健康受试者会完全转变为类似哮喘的高反应性肺状态。
