Gourlay Terence, Samartzis Ioannis, Taylor Kenneth M
Department of Cardiac Surgery, NHLI, Imperial College London, Faculty of Medicine, Hammersmith Hospital, London, UK.
Perfusion. 2003 Apr;18(2):87-93. doi: 10.1191/0267659103pf648oa.
Modern cardiopulmonary bypass (CPB) systems are getting smaller, both in terms of the exposed surface area of biomaterials and the priming volume. In a series of studies utilizing a rat recirculation model, we demonstrated that the magnitude of the inflammatory response seen under these conditions is proportional to the surface area of exposed material, a finding that supports the use of miniature systems in terms of moderating the inflammatory response. However, the second impact of miniature perfusion systems, the reduced priming volume with concomitant reduction in haemodilution, was not investigated with reference to inflammation. The present study was designed to determine whether this change in CPB haematocrit profile has any effect on the inflammatory response. In common with previous studies by this group, we employed the expression of the integrin CD11b on neutrophils as a marker of neutrophil activation, and hence the inflammatory response, in a rat recirculation biomaterial testing model, containing di-(2-ethyl-hexyl)-phthalate plasticized polyvinyl chloride of the type commonly employed in CPB circuits. The results demonstrated that neutrophil activation is influenced by haemodilution. We studied five groups of animals, each with different mean induced haematocrit: Group 1 (41.3 +/- 1.27%); Group 2 (30.93 +/- 2.85%); Group 3 (24.83 +/- 1.36%); Group 4 (20.60 +/- 3.47%); Group 5 (20.48 +/- 1.31%). Groups 1 and 5 animals were controls, neither of which underwent the period of recirculation. Rather, these controls were employed to isolate the noncontact effect of haemodilution on CD11b expression. We found that there were differences in per cent change in CD11b expression from start to end of the recirculation period between Group 1 (109.54 +/- 49.53%), Group 2 (189.1 +/- 18.68%), Group 3 (224.28 +/- 43.97), Group 4 (368.97 +/- 24.28%) and Group 5 (127 +/- 57.8%). There were intergroup statistically significant differences (p < 0.05). These results confirm that there is a relationship between haematocrit level and biomaterial contact-mediated activation of neutrophils. Furthermore, these studies confirm that haemodilution alone has no effect on neutrophil activation. One possible explanation for this outcome is that with higher levels of haemodilution, neutrophils have a greater opportunity to contact surface 'receptor' sites on the biomaterial, resulting in more neutrophil activation. Whatever the mechanism, these data tend to support the modern trend towards lower circuit surface area and higher haematocrit.
现代体外循环（CPB）系统在生物材料的暴露表面积和预充量方面都越来越小。在一系列利用大鼠再循环模型的研究中，我们证明了在这些条件下观察到的炎症反应程度与暴露材料的表面积成正比，这一发现支持了使用微型系统来减轻炎症反应。然而，微型灌注系统的第二个影响，即预充量减少以及随之而来的血液稀释减少，并未针对炎症进行研究。本研究旨在确定CPB血细胞比容曲线的这种变化是否对炎症反应有任何影响。与该研究小组之前的研究一样，我们在包含CPB回路中常用的邻苯二甲酸二（2-乙基己基）酯增塑聚氯乙烯的大鼠再循环生物材料测试模型中，采用中性粒细胞上整合素CD11b的表达作为中性粒细胞活化的标志物，从而作为炎症反应的标志物。结果表明，中性粒细胞活化受血液稀释的影响。我们研究了五组动物，每组具有不同的平均诱导血细胞比容：第1组（41.3±1.27%）；第2组（30.93±2.85%）；第3组（24.83±1.36%）；第4组（20.60±3.47%）；第5组（20.48±1.31%）。第1组和第5组动物为对照组，两组均未经历再循环期。相反，这些对照组用于分离血液稀释对CD11b表达的非接触效应。我们发现，第1组（109.54±49.53%）、第2组（189.1±18.68%）、第3组（224.28±43.97）、第4组（368.97±24.28%）和第5组（127±57.8%）在再循环期开始到结束时CD11b表达的变化百分比存在差异。组间存在统计学显著差异（p<0.05）。这些结果证实血细胞比容水平与生物材料接触介导的中性粒细胞活化之间存在关联。此外，这些研究证实单纯的血液稀释对中性粒细胞活化没有影响。这一结果的一个可能解释是，随着血液稀释程度的增加，中性粒细胞有更多机会接触生物材料表面的“受体”位点，从而导致更多的中性粒细胞活化。无论机制如何，这些数据倾向于支持降低回路表面积和提高血细胞比容的现代趋势。
