Yap Choon Hwai, Lai Chang Quan, Loh Ivan Guang Hui, Ong Thaddaeus Zhongren
Department of Biomedical Engineering, National University of Singapore, Singapore.
Department of Mechanical Engineering, National University of Singapore, Singapore.
Artif Organs. 2017 Feb;41(2):178-185. doi: 10.1111/aor.12731. Epub 2016 Sep 22.
Roller pumps are widely used in many medical procedures including cardiopulmonary bypass, left/right ventricular assist, and hemodialysis. However, to date, the problem of the roller pumping mechanism causing significant hemolysis remains unresolved. It has been shown that with under-occlusion of the roller pump, hemolysis can be reduced, but significant reduction of the mean flow rate also takes place due to backflow through the under-occlusion. We performed an investigation of the flow dynamics of an under-occluded roller pump which featured significantly higher amount of under-occlusion than previously investigated. Our results showed that the mean flow rate produced by the pump has a strong, nonlinear dependence on pumping frequency. Mean flow rate generally increases with the pumping frequency and the degree of maximum occlusion except at certain frequencies where sharp reductions were observed. These frequencies coincide with the fundamental frequency of the system and its harmonics, bearing resemblance to the impedance pump, suggesting that the drastically under-occluded roller pump is a unique device that employs the pumping mechanisms of both roller pumping and impedance pumping. At the appropriate frequencies, this under-occluded roller pump could sustain sufficiently high flow rates for clinical uses. Blood damage potential of the under-occluded roller pump was compared to a fully occluded roller pump via the assay of free-plasma hemoglobin, and it was found that the under-occlusion reduced hemolysis by about half for any given flow rate. The drastically under-occluded roller pumping reported in this study, therefore, has the potential of being translated into an improved clinical blood pump.
滚压泵广泛应用于许多医疗程序，包括体外循环、左/右心室辅助和血液透析。然而，迄今为止，滚压泵机制导致严重溶血的问题仍未得到解决。研究表明，当滚压泵未完全闭塞时，溶血可以减少，但由于未完全闭塞处的回流，平均流速也会显著降低。我们对一种未完全闭塞的滚压泵的流动动力学进行了研究，该泵的未完全闭塞程度比之前研究的要高得多。我们的结果表明，该泵产生的平均流速对泵浦频率有很强的非线性依赖性。平均流速通常随着泵浦频率和最大闭塞程度的增加而增加，但在某些频率处会出现急剧下降。这些频率与系统的基频及其谐波一致，类似于阻抗泵，这表明严重未完全闭塞的滚压泵是一种独特的装置，它采用了滚压泵和阻抗泵的泵浦机制。在适当的频率下，这种未完全闭塞的滚压泵可以维持足够高的流速用于临床。通过检测游离血浆血红蛋白，将未完全闭塞的滚压泵的血液损伤潜力与完全闭塞的滚压泵进行了比较，发现在任何给定流速下，未完全闭塞可使溶血减少约一半。因此，本研究中报道的严重未完全闭塞的滚压泵有潜力转化为一种改进的临床血泵。
