Perfusion
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The use of extracorporeal life support (ECLS) is considered in children who (1) have an acute life-threatening heart or lung disease, (2) are normal before the illness and are likely to be normal if they survive, and (3) have an 80% chance of death. Our use of a constrained vortex pump (CVP) offers a number of potential advantages compared to a roller pump. ⋯ Since May 1989 at the Royal Children's Hospital, Melbourne, Australia, we have provided ECLS to 30 neonates (20 of whom survived) and 22 children (eight of whom survived). ECLS is a useful technique for supporting patients who are unable to be adequately ventilated or oxygenated or who have an inadequate cardiac output.
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Femoro-femoral bypass is an established technique in the armamentarium of cardiac surgeons, but poor venous drainage usually restricts the flow rate that can be achieved. We describe a technique whereby full flow ( greater than 2.41 l/min/m 2 femoro-femoral bypass) can be achieved with a 17 F arterial and a single 21 F venous cannula placed percutaneously or via a cut-down. Transoesophageal echo is used to position the tip of the venous cannula accurately in the right atrium. The circuit includes a centrifugal pump on the venous side, pumping into a reservoir; a conventional roller pump delivers blood through the arterial cannula. A parallel arrangement allows the centrifugal pump to be excluded from the circuit at any stage. The system allows flow rates over 2.4 l/min/m 2 despite the size of the venous cannula; without the centrifugal pump working maximal flow rates are under 1.5 l/min/m 2. The right side of the heart is totally decompressed and there is no need to add volume or vasopressors to maintain the desired full flow rate. Once the chest is open, perfusion may continue as before or gravity drainage can be utilized after stopping the centrifugal pump; venous return may be augmented by placing additional cannulae. If desired, slowing drainage by the centrifugal pump temporarily permits the blind placement of a coronary sinus cannula without entraining air.(ABSTRACT TRUNCATED AT 250 WORDS)
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The present experiment examined the capacity of the Carmeda Bioactive Surface to prevent clot formation in an ECMO circuit designed for neonatal use. The Terumo Capiox oxygenator was used in the seven experiments. Mongrel dogs were perfused with veno-arterial bypass at a low flow rate of 200 ml/min. ⋯ With a very low heparin infusion (10 IUxkg -1xh -1) extracorporeal blood flow could be maintained despite some clots forming in the oxygenator. With a small bolus injection of heparin (20 IU/kg) and a low continuous heparin infusion (20 IUxkg -1xh -1) the ECMO circuit showed negligible clotting. With better haemodynamic design of the device in combination with a thrombo-resistant surface, it may be possible to decrease the need for blood heparinization in the neonatal ECMO circuit.
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Randomized Controlled Trial Clinical Trial
Clinical experience with heparin-coated cardiopulmonary bypass circuits.
The extensive area of contact between blood and synthetic surfaces during cardiopulmonary bypass results in the activation of the kallikrein, the complement and the clotting and fibrinolytic systems. This results in white cell activation and a whole body inflammatory response. Pulmonary neutrophil sequestration is also known to occur during cardiopulmonary bypass and has been associated with pulmonary damage. ⋯ The preliminary results suggest a reduction in pulmonary neutrophil sequestration (p greater than 0.05) and the generation of thrombin antithrombin complexes (p less than 0.05). Retinal microembolism was not significantly different in the two groups nor was the postoperative blood loss. Thus, heparin-coated cardiopulmonary bypass circuits do not reduce pulmonary neutrophil sequestration, retinal microembolism or postoperative blood loss.