Department of Surgery, University of Michigan, Ann Arbor, USA.
ASAIO J. 2012 Jul-Aug;58(4):426-31. doi: 10.1097/MAT.0b013e318256bb36.
Recent thoracic artificial lung (TAL) prototypes have impedances lower than the natural lung. With these devices, proximal pulmonary artery (PA) to distal PA TAL attachment may be possible in patients without right ventricular dysfunction. This study examined the relationship between pulmonary system impedance and cardiac output (CO) to create TAL design constraints. A circuit with adjustable resistance and compliance (C) was attached in a PA-PA fashion with the pulmonary circulation of seven sheep with chronic pulmonary hypertension. The pulmonary system zeroth harmonic impedance modulus (Z(0)) was increased by 1, 2.5, and 4 mmHg/(L/min) above baseline. At each Z(0), C was set to 0, 0.34, and 2.1 ml/mmHg. The change in pulmonary system zeroth and first harmonic impedance moduli (ΔZ(0) and ΔZ(1)), the percent change in CO (%ΔCO), and the inlet and outlet anastomoses resistances were calculated for each situation. Results indicate that ΔZ(0) (p < 0.001) but not ΔZ(1) (p = 0.5) had a significant effect on %ΔCO and that %ΔCO = -7.45*ΔZ(0) (R(2) = 0.57). Inlet and outlet anastomoses resistances averaged 0.77 ± 0.16 and 0.10 ± 0.19 mmHg/(L/min), respectively, and the relationship between %ΔCO and TAL resistance, R(T), in mmHg/(L/min) was determined to be %ΔCO = -(7.45f)×(R(T) + 0.87), in which f = the fraction of CO through the TAL. Thus, newer TAL designs can limit %ΔCO to less than 10% if f < 0.75.
最近的胸人工肺（TAL）原型的阻抗低于自然肺。有了这些设备，在没有右心室功能障碍的患者中，近端肺动脉（PA）到远端 PA TAL 附着可能成为可能。本研究检查了肺系统阻抗与心输出量（CO）之间的关系，以创建 TAL 设计约束。在七只患有慢性肺动脉高压的绵羊的肺循环中，以 PA-PA 方式连接了一个具有可调电阻和顺应性（C）的电路。肺系统零阶谐波阻抗模（Z(0)）比基线增加 1、2.5 和 4mmHg/（L/min）。在每个 Z(0)，C 设置为 0、0.34 和 2.1ml/mmHg。计算了肺系统零阶和一阶谐波阻抗模的变化（ΔZ(0)和ΔZ(1)）、CO 的百分比变化（%ΔCO）以及入口和出口吻合口阻力。结果表明，ΔZ(0)（p<0.001）但不是ΔZ(1)（p=0.5）对%ΔCO 有显著影响，并且%ΔCO=-7.45ΔZ(0)（R(2)=0.57）。入口和出口吻合口阻力平均为 0.77±0.16 和 0.10±0.19mmHg/（L/min），并且%ΔCO 与 TAL 阻力，R(T)，在 mmHg/（L/min）之间的关系被确定为%ΔCO=-(7.45f)(R(T)+0.87)，其中 f=通过 TAL 的 CO 分数。因此，如果 f<0.75，新型 TAL 设计可以将%ΔCO 限制在 10%以下。
