Pulmonary Division, Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada.
Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Edmonton, Alberta, Canada.
BMJ Open Respir Res. 2023 Dec 22;10(1):e001791. doi: 10.1136/bmjresp-2023-001791.
Individuals with asthma breathe at higher operating lung volumes during exercise compared with healthy individuals, which contributes to increased exertional dyspnoea. In health, females are more likely to develop exertional dyspnoea than males at a given workload or ventilation, and therefore, it is possible that females with asthma may develop disproportional dyspnoea on exertion. The purpose of this study was to compare operating lung volume and dyspnoea responses during exercise in females with and without asthma.
Sixteen female controls and 16 females with asthma were recruited for the study along with 16 male controls and 16 males with asthma as a comparison group. Asthma was confirmed using American Thoracic Society criteria. Participants completed a cycle ergometry cardiopulmonary exercise test to volitional exhaustion. Inspiratory capacity manoeuvres were performed to estimate inspiratory reserve volume (IRV) and dyspnoea was evaluated using the Modified Borg Scale.
Females with asthma exhibited elevated dyspnoea during submaximal exercise compared with female controls (p<0.05). Females with asthma obtained a similar IRV and dyspnoea at peak exercise compared with healthy females despite lower ventilatory demand, suggesting mechanical constraint to tidal volume (V) expansion. V-inflection point was observed at significantly lower ventilation and O in females with asthma compared with female controls. Forced expired volume in 1 s was significantly associated with V-inflection point in females with asthma (R=0.401; p<0.01) but not female controls (R=0.002; p=0.88).
These results suggest that females with asthma are more prone to experience exertional dyspnoea, secondary to dynamic mechanical constraints during submaximal exercise when compared with females without asthma.
与健康个体相比，哮喘患者在运动时以更高的肺功能残气量（operating lung volume）进行呼吸，这导致运动性呼吸困难加重。在健康人群中，女性在给定的工作量或通气量下比男性更容易出现运动性呼吸困难，因此，哮喘女性在运动时可能会出现不成比例的呼吸困难。本研究的目的是比较哮喘女性与非哮喘女性在运动时的肺功能残气量和呼吸困难反应。
本研究纳入了 16 名哮喘女性、16 名非哮喘女性、16 名哮喘男性和 16 名非哮喘男性作为对照组。哮喘通过美国胸科学会标准确诊。参与者完成了一项至力竭的心肺运动测试，以评估呼吸储备量（IRV）并采用改良 Borg 量表评估呼吸困难。
与非哮喘女性相比，哮喘女性在亚极量运动时表现出更高的呼吸困难（p<0.05）。尽管通气需求较低，但哮喘女性在达到峰值运动时与健康女性具有相似的 IRV 和呼吸困难，这表明存在机械性限制潮气量（V）扩张。与非哮喘女性相比，哮喘女性的 V 拐点出现在显著较低的通气和 O 水平。在哮喘女性中，用力呼气 1 秒量（FEV1）与 V 拐点显著相关（R=0.401；p<0.01），而非哮喘女性则不相关（R=0.002；p=0.88）。
这些结果表明，与非哮喘女性相比，哮喘女性在亚极量运动时更容易出现运动性呼吸困难，这可能是由于动态机械限制所致。
