Kirkness Jason P, Christenson Hugo K, Wheatley John R, Amis Terence C
Ludwig Engel Centre for Respiratory Research, Westmead Hospital and University of Sydney, NSW, Australia.
Physiol Meas. 2005 Oct;26(5):677-88. doi: 10.1088/0967-3334/26/5/009. Epub 2005 Jun 13.
Upper airway luminal patency is influenced by a number of factors including: intraluminal air pressure, upper airway dilator muscle activity, surrounding extraluminal tissue pressure and surface tension acting within the liquid layer lining the upper airway. In this study we examine the performance characteristics for the 'pull-off' force method for measuring the surface tension (gamma) of liquids. This method is then used to examine the gamma of the liquid lining the oro-pharynx in awake human subjects. The gamma of UAL samples (approximately 0.2 microL) obtained from the posterior pharyngeal wall was quantified using the pull-off force technique in which gamma is measured as the force required to separate two curved silica discs bridged by the liquid sample. Pull-off force measurement was not influenced by sample volumes or under different temperature or humidity conditions. The coefficients of variation for repeated measurements using the pull-off force technique for the three standard liquids ranged from 1.2% to 5.6%. The pull-off method tended to give slightly lower values than the Wihelmy balance method with the mean difference being 2.4 +/- 1.8 mN m(-1). For the group, the gamma of saliva was 59.2 +/- 0.6 mN m(-1) (CV 4.9 +/- 0.9%) for five measurements of a single sample. There was no significant relationship between the measured gamma values for five subjects measured on five separate days and the day of collection of the sample for any of the subjects or the group as a whole (both p > 0.6). There was no significant difference (p = 0.53, ANOVA) between the gamma values for samples obtained from under the tongue (61.6 +/- 1.7 mN m(-1)), at the oral surface of the soft palate (56.1 +/- 3.2 mN m(-1)) and from the posterior oro-pharyngeal wall (58.1 +/- 2.4 mN m(-1)). The pull-off force method provides adequate reproducibility to be able to measure the gamma of UAL. In healthy humans the gamma of UAL is similar to that of saliva.
上气道管腔通畅性受多种因素影响，包括：管腔内气压、上气道扩张肌活动、周围管腔外组织压力以及作用于上气道内衬液层内的表面张力。在本研究中，我们检测了用于测量液体表面张力（γ）的“拉脱”力法的性能特征。然后使用该方法检测清醒人类受试者口咽内衬液体的γ。从咽后壁获取的上气道液体（UAL）样本（约0.2微升）的γ，采用拉脱力技术进行定量，其中γ被测量为分离由液体样本桥接的两个弯曲硅胶盘所需的力。拉脱力测量不受样本体积影响，也不受不同温度或湿度条件影响。使用拉脱力技术对三种标准液体进行重复测量的变异系数在1.2%至5.6%之间。拉脱法得到的值往往比威尔海姆天平法略低，平均差值为2.4±1.8 mN m⁻¹。对于该组，单个样本五次测量的唾液γ为59.2±0.6 mN m⁻¹（CV 4.9±0.9%）。在五个不同日期对五名受试者测量的γ值与任何受试者或整个组样本采集日之间均无显著关系（两者p>0.6）。从舌下（61.6±1.7 mN m⁻¹）、软腭口腔表面（56.1±3.2 mN m⁻¹）和口咽后壁（58.1±2.4 mN m⁻¹）获取的样本γ值之间无显著差异（p = 0.53，方差分析）。拉脱力法具有足够的重现性，能够测量UAL的γ。在健康人类中，UAL的γ与唾液的γ相似。
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