By airway surface liquid, we mean a thin fluid continuum consisting of the airway lining layer and the alveolar lining layer, which not only serves as a protective barrier against foreign particles but also contributes to maintaining normal respiratory mechanics. In recent years, measurements of the rheological properties of airway surface liquid have attracted considerable clinical attention due to new advances in microrheology instruments and methods. This article reviews the clinical relevance of measurements of airway surface liquid viscoelasticity and surface tension from four main aspects: maintaining the stability of the airways and alveoli, preventing ventilator-induced lung injury, optimizing surfactant replacement therapy for respiratory syndrome distress, and characterizing the barrier properties of airway mucus to improve drug and gene delivery. Primary measuring techniques and methods suitable for determining the viscoelasticity and surface tension of airway surface liquid are then introduced with respect to principles, advantages and limitations. Cone and plate viscometers and particle tracking microrheometers are the most commonly used instruments for measuring the bulk viscosity and microviscosity of airway surface liquid, respectively, and pendant drop methods are particularly suitable for the measurement of airway surface liquid surface tension in vitro. Currently, in vivo and in situ measurements of the viscoelasticity and surface tension of the airway surface liquid in humans still presents many challenges.

中文翻译：

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气道表面液的流变学和表面张力的测定：临床相关性和测量技术的综述。

气道表面液体是指由气道内衬层和肺泡内衬层组成的稀薄的流体连续体，它不仅可作为防护异物的屏障，而且有助于维持正常的呼吸力学。近年来，由于微流变仪和方法的新进展，对气道表面液流变特性的测量已引起相当大的临床关注。本文从四个主要方面回顾了测量气道表面液体粘弹性和表面张力的临床意义：维护气道和肺泡的稳定性，预防呼吸机诱发的肺损伤，优化用于呼吸综合征的窘迫的表面活性剂替代疗法，并表征气道粘液的屏障特性，以改善药物和基因的传递。然后针对原理，优点和局限性，介绍适用于确定气道表面液体粘弹性和表面张力的主要测量技术和方法。锥板粘度计和颗粒跟踪微流变仪是分别用于测量气道表面液的体积粘度和微粘度的最常用仪器，悬滴法尤其适用于体外测量气道表面液的表面张力。目前，人体中气道表面液体的粘弹性和表面张力的体内和原位测量仍然提出了许多挑战。然后针对原理，优点和局限性，介绍适用于确定气道表面液体粘弹性和表面张力的主要测量技术和方法。锥板粘度计和颗粒跟踪微流变仪是分别用于测量气道表面液体的体积粘度和微粘度的最常用仪器，悬滴法特别适用于体外测量气道表面液体的表面张力。目前，人体中气道表面液体的粘弹性和表面张力的体内和原位测量仍然提出许多挑战。然后针对原理，优点和局限性，介绍适用于确定气道表面液体粘弹性和表面张力的主要测量技术和方法。锥板粘度计和颗粒跟踪微流变仪是分别用于测量气道表面液体的体积粘度和微粘度的最常用仪器，悬滴法特别适用于体外测量气道表面液体的表面张力。目前，人体中气道表面液体的粘弹性和表面张力的体内和原位测量仍然提出了许多挑战。锥板粘度计和颗粒跟踪微流变仪是分别用于测量气道表面液的体积粘度和微粘度的最常用仪器，悬滴法尤其适用于体外测量气道表面液的表面张力。目前，人体中气道表面液体的粘弹性和表面张力的体内和原位测量仍然提出了许多挑战。锥板粘度计和颗粒跟踪微流变仪是分别用于测量气道表面液体的体积粘度和微粘度的最常用仪器，悬滴法特别适用于体外测量气道表面液体的表面张力。目前，人体中气道表面液体的粘弹性和表面张力的体内和原位测量仍然提出许多挑战。