Hendrix Rik H J, Ganushchak Yuri M, Weerwind Patrick W
Department of Extra-Corporeal Circulation, Maastricht University Medical Centre, Maastricht, The Netherlands.
Artif Organs. 2018 Jun;42(6):611-619. doi: 10.1111/aor.13084. Epub 2018 Feb 23.
Design of contemporary oxygenators requires better understanding of the influence of hydrodynamic patterns on gas exchange. A decrease in blood path width or an increase in intraoxygenator turbulence for instance, might increase gas transfer efficiency but it will increase shear stress as well. The aim of this clinical study was to examine the association between shear stress and oxygen and carbon dioxide transfer in different contemporary oxygenators during cardiopulmonary bypass (CPB). The effect of additional parameters related to gas transfer efficiency, that is, blood flow, gas flow, sweep gas oxygen fraction (FiO ), hemoglobin concentration, the amount of hemoglobin pumped through the oxygenator per minute-Qhb, and shunt fraction were contemplated as well. Data from 50 adult patients who underwent elective CPB for coronary artery bypass grafting or aortic valve replacement were retrospectively analyzed. Data included five different oxygenator types with an integrated arterial filter. Relationships were determined using Pearson bivariate correlation analysis and scatterplots with LOESS curves. In the Capiox FX25, Fusion, Inspire 8F, Paragon, and Quadrox-i groups, mean blood flows were 4.8 ± 0.9, 5.3 ± 0.7, 4.9 ± 0.7, 5.0 ± 0.6, and 5.7 ± 0.6 L/min, respectively. The mean O transfer/m membrane surface area was 44 ± 14, 51 ± 9, 60 ± 10, 63 ± 14, and 77 ± 18, respectively, whereas the mean CO transfer/m was 26 ± 14, 60 ± 22, 73 ± 29, 74 ± 19, and 96 ± 20, respectively. Associations between oxygen transfer/m and shear stress differed per oxygenator, depending on oxygenator design and the level of shear stress (r = 0.249, r = 0.562, r = 0.402, r = 0.465, and r = 0.275 for Capiox FX25, Fusion, Inspire 8F, Paragon, and Quadrox-i, respectively, P < 0.001 for all). Similar associations were noted between CO transfer/m and shear stress (r = 0.303, r = 0.439, r = 0.540, r = 0.392, and r = 0.538 for Capiox FX25, Fusion, Inspire 8F, Paragon, and Quadrox-i, respectively, P < 0.001 for all). In addition, O transfer/m was strongly correlated with FiO (r = 0.633, P < 0.001), blood flow (r = 0.529, P < 0.001), and Qhb (r = 0.589, P < 0.001). CO transfer/m in contrast was predominately correlated to sweep gas flow (r = 0.567, P < 0.001). The design-dependent relationship between shear stress and gas transfer revealed that every oxygenator has an optimal range of blood flow and thus shear stress at which gas transfer is most efficient. Gas transfer is further affected by factors influencing the O or CO concentration gradient between the blood and the gas compartment.
当代氧合器的设计需要更好地理解流体动力学模式对气体交换的影响。例如，血液路径宽度减小或氧合器内湍流增加可能会提高气体传输效率，但也会增加剪切应力。本临床研究的目的是探讨在体外循环（CPB）期间不同当代氧合器中剪切应力与氧气和二氧化碳传输之间的关联。还考虑了与气体传输效率相关的其他参数的影响，即血流量、气体流量、吹扫气氧分数（FiO）、血红蛋白浓度、每分钟通过氧合器泵入的血红蛋白量-Qhb以及分流分数。对50例接受择期CPB进行冠状动脉搭桥术或主动脉瓣置换术的成年患者的数据进行了回顾性分析。数据包括五种不同类型且带有集成动脉过滤器的氧合器。使用Pearson双变量相关性分析以及带有局部加权散点平滑法（LOESS）曲线的散点图来确定关系。在Capiox FX25、Fusion、Inspire 8F、Paragon和Quadrox-i组中，平均血流量分别为4.8±0.9、5.3±0.7、4.9±0.7、5.0±0.6和5.7±0.6 L/分钟。每平方米膜表面积的平均氧气传输量分别为44±14、51±9、60±10、63±14和77±18，而每平方米的平均二氧化碳传输量分别为26±14、60±22、73±29、74±19和96±20。每平方米氧气传输量与剪切应力之间的关联因氧合器而异，这取决于氧合器设计和剪切应力水平（Capiox FX25、Fusion、Inspire 8F、Paragon和Quadrox-i的r分别为0.249、0.562、0.402、0.465和0.275，所有P均<0.001）。在二氧化碳传输量与剪切应力之间也观察到类似的关联（Capiox FX25、Fusion、Inspire 8F、Paragon和Quadrox-i的r分别为0.303、0.439、0.540、0.392和0.538，所有P均<0.001）。此外，每平方米氧气传输量与FiO（r = 0.633，P < 0.001）、血流量（r = 0.529，P < 0.001）和Qhb（r = 0.589，P < 0.001）密切相关。相比之下，每平方米二氧化碳传输量主要与吹扫气体流量相关（r = 0.567，P < 0.001）。剪切应力与气体传输之间的设计依赖性关系表明，每个氧合器都有一个最佳的血流量范围，因此也有一个最佳的剪切应力范围，在此范围内气体传输效率最高。气体传输还受到影响血液与气体腔室之间氧气或二氧化碳浓度梯度的因素的进一步影响。
