Studies of Extracorporeal Membrane Oxygenation (ECMO) for Neonatal Acute Respiratory Failure

传统的带滚柱泵的ECMO回路并不总是没有严重的机械问题，如静脉破裂、空气栓塞、动脉破裂。研制了一种新型、安全、实用的带自动血泵的ECMO电路。我们的新生儿ECMO电路准备了65ml，包括带有4 mm球阀的血泵和一个0.5平方米的膜式氧合器。我们的儿科ECMO回路预置了120毫升的6 mm瓣膜和0.8平方米的膜式氧合器。该泵可以根据其充注量自动改变输出，因此不会产生过大的负压。我们的ECMO电路已经在模拟循环系统上进行了广泛的测试，并在狗身上使用。在模拟循环系统上连续行驶21天，没有遇到机械故障。体外循环流量随静脉回流而自动变化，但在动脉压变化时保持恒定。我们在50只狗身上研究了使用我们的自动血泵的ECMO对血流动力学的影响。在VA-ECMO期间，平均肺动脉压和右室压下降。当流量增加超过50ml/kg/min时，主动脉收缩压比左心室收缩压下降更明显。高旁路流量时，左、右室舒张内压均升高。综上所述，我们的自动ECMO电路是治疗小婴儿急性呼吸衰竭的一种安全有效的装置，但由于VA-ECMO流量可能对心脏有不良影响，因此应尽量减少VA-ECMO流量。

Conventional ECMO circuits with a roller pump are not always free from serious mechanical problems like venous collapse, air embolism, burst of the arterial line. A new, safer, and more practical ECMO circuit with an automatic blood pump was developed. Our neonatal ECMO circuit primed 65 ml consisted of blood pumps with 4 mm ball valves and a membrane oxygenator of 0.5 sq.m. Our pediatric ECMO circuit primed 120 ml with 6 mm valves and a membrane oxygenator of 0.8 sq.m. The pump could change output automatically in response to its filling and thereby did not produce excessive negative pressure.Our ECMO circuits had been extensively tested on a mock circulation system and used on dogs. No mechanical problem had been encountered in continuous driving on the mock circulation system for 21 days. Bypass flow changed automatically in response to venous return, but remained constant against changes in arterial pressure.Effect of ECMO using our automatic blood pumps on hemodynamics was studied on 50 dogs. During VA-ECMO mean pulmonary arterial pressure and right ventricular pressure decreased. When the flow increased more than 50 ml/kg/min, the aortic systolic pressure tended to decrease more significantly than the systolic left ventricular pressure. The endodiastric pressure in both right and left ventricles elevated at high bypass flow. These findings indicated that VA-ECMO of high frow caused ventricular strain.In conclusion, our automatic ECMO circuit is a safe and useful device treating small infants with acute respiratory failure but VA-ECMO flow should be kept as little as possible because of possible ill effects on the heart.