Brengelmann G L, Savage M
J Appl Physiol (1985). 1986 Sep;61(3):1210-6. doi: 10.1152/jappl.1986.61.3.1210.
Strain gauges employed in plethysmography for determination of limb blood flow tend to counter the expansion of the limb during venous occlusion. Traditionally a mechanical calibration is performed in situ to compensate for tissue compressibility. Greenfield, Whitney, and Mowbray stated that, otherwise, large errors would result (Br. Med. Bull. 19: 101-109, 1963). Nonetheless, not all of the recent reports on skin blood flow in humans have been based on a calibration procedure that corrects for tissue compressibility. To evaluate the significance of this problem, we developed a new strain-gauge holder that made possible frequent, reproducible, stretching of a single-strand Whitney gauge in situ. We compared the apparent sensitivity thus obtained to electrical or bench mechanical determinations. We independently determined tissue compressibility by recording limb circumference as tension in a circumferential tube was varied. Both techniques showed that tissue compressibility is a small source of error (5%) and that compressibility decreases during occlusion. Therefore the cumbersome holder and potential artifacts associated with the traditional technique need not be tolerated. We also investigated the consequences of nonuniform tension distribution and temperature changes; practical considerations for dealing with these are discussed.
用于测定肢体血流量的体积描记术中所使用的应变计往往会抵抗静脉阻塞期间肢体的扩张。传统上，会在原位进行机械校准以补偿组织的可压缩性。格林菲尔德、惠特尼和莫布雷指出，否则会导致很大的误差（《英国医学公报》19: 101 - 109, 1963）。然而，并非所有近期关于人体皮肤血流量的报告都基于校正组织可压缩性的校准程序。为了评估这个问题的重要性，我们开发了一种新的应变计固定器，它能够在原位对单股惠特尼应变计进行频繁、可重复的拉伸。我们将由此获得的表观灵敏度与电学或台式机械测定结果进行了比较。我们通过记录随着圆周管中的张力变化时肢体周长，独立测定了组织的可压缩性。两种技术均表明，组织可压缩性是一个较小的误差来源（5%），并且在阻塞过程中可压缩性会降低。因此，与传统技术相关的麻烦的固定器和潜在的假象无需忍受。我们还研究了张力分布不均匀和温度变化的后果；讨论了处理这些问题的实际考虑因素。
