Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, USA.
Ann Biomed Eng. 2010 Dec;38(12):3649-63. doi: 10.1007/s10439-010-0120-5. Epub 2010 Jul 13.
Gas bubble motion in a blood vessel causes temporal and spatial gradients of shear stress at the cell surface lining the vessel wall as the bubble approaches the cell, moves over it and passes it by. Rapid reversals occur in the sign of the shear stress imparted to the cell surface during this motion. These may result in injury to the cell. The presence of a soluble surfactant in the bulk medium reduces the level of the shear stress gradients imparted to the cell surface as compared to an equivalent surfactant-free system and is an important therapeutic aid. This is particularly true for a very small vessel. In this study, we analyze various physical and chemical properties of any given soluble surfactant to ascertain the relative significance of the property of the surfactant on the reduction in the level of the shear stress gradients imparted to the cell surface in such a vessel. While adsorption, desorption, and maximum possible monolayer interface surfactant concentration significantly impact the shear stress levels, physical properties such as the bulk or surface diffusivity do not appear to have large effects. At a given diameter, surfactants with k(a)/(k(d)d>O(10)⁻⁵ and Γ(∞)/C(0)d>9.5 x 10⁻⁴ are noted to be preferable from the point of view of an increased gap size between the bubble and vessel wall, and a corresponding reduction in the shear stress level imparted to an endothelial cell. The shear stress characteristics of nearly occluding bubbles, in contrast with smaller sized bubbles under identical conditions, are most affected by the introduction of a surfactant in regard to shear stress levels. These observations could form a basis for choosing surfactants in treating gas embolism related illnesses.
气泡在血管中运动时，会在靠近细胞、经过细胞和远离细胞的过程中，在血管壁衬里细胞表面产生暂时的和空间的切变应力梯度。在这种运动过程中，作用于细胞表面的切变应力的符号会迅速反转。这可能导致细胞损伤。在大量介质中存在可溶表面活性剂会降低作用于细胞表面的切变应力梯度水平，与等效的无表面活性剂系统相比，这是一种重要的治疗辅助手段。对于非常小的血管尤其如此。在这项研究中，我们分析了给定的可溶表面活性剂的各种物理和化学性质，以确定表面活性剂的性质对降低此类血管中作用于细胞表面的切变应力梯度水平的相对重要性。虽然吸附、解吸和最大可能单层界面表面活性剂浓度对切变应力水平有显著影响，但物理性质如体相或表面扩散似乎没有太大影响。在给定的直径下，k(a)/(k(d)d>O(10)⁻⁵和Γ(∞)/C(0)d>9.5 x 10⁻⁴的表面活性剂被认为是优选的，因为气泡和血管壁之间的间隙尺寸增加，以及作用于内皮细胞的切变应力水平相应降低。与相同条件下较小尺寸的气泡相比，几乎闭塞气泡的切变应力特性在引入表面活性剂方面受切变应力水平的影响最大。这些观察结果可以为治疗与气体栓塞相关的疾病选择表面活性剂提供依据。
