ASAIO transactions / American Society for Artificial Internal Organs
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The authors designed and tested a 14F outside diameter thin-walled double lumen catheter (DLC) for neonatal venovenous (VV) extracorporeal membrane oxygenation (ECMO). In vitro tests with water and dye solution showed capacity of the drainage lumen was 1,096 ml/min at 100 cm siphon, and pressure drop across the perfusion lumen was 300 mmHg at 500 ml/min flow. ⋯ Typical oxygen transport in four dogs was 25 cc/min at 400 ml/min flow. This catheter is well suited for clinical VV ECMO in neonates.
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To determine changes in blood flow to different organs during extracorporeal membrane oxygenation (ECMO), the authors performed venoarterial ECMO in four young lambs for 71-96 hr (Group 1). Macroaggregated albumin microspheres labeled with technetium 99m were injected through the perfusion cannula before termination of ECMO to determine percent of blood flow by measuring radioactivity from the microspheres lodged in specific organs. The control group (Group 2) consisted of three animals not on bypass; injections were made through a catheter placed in the left ventricle. ⋯ Contrary to observations in rabbits, cerebral perfusion did not decrease in the bypass group despite ligation of the carotid artery and the external jugular vein. There were no statistically significant differences between the two groups in the relative blood flow to other organs. The authors conclude that ECMO may significantly alter myocardial and renal perfusion, with minimal effects to other organs.
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Improvements in percutaneous coronary angioplasty (PTCA) have broadened the scope of this therapy to higher risk patients. The authors used an extracorporeal membrane oxygenator (ECMO) system during seven PTCA procedures to provide rapid, safe, cardiopulmonary support for high-risk patients. Six patients underwent femoral cutdown and placement of arteriovenous cannulae before PTCA; one patient was cannulated percutaneously. ⋯ One patient died of retroperitoneal hemorrhage unrelated to the ECMO cannulation site. Six patients survived. This system can be rapidly deployed while providing satisfactory cardiopulmonary support.
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A simple, colorimetric protamine titration method was developed for rapid and precise estimation of the protamine dose required for clinical heparin reversal. The method employs azure A dye as the titration indicator, and has replaced the time consuming clotting assay in the conventional protamine titration method with a rapid colorimetric assay. ⋯ In a similar manner, the colorimetric assay can also be employed with a heparin titration procedure to quickly assess the heparin dose required for protamine reversal. This would allow physicians to exercise a quick and accurate heparin back-titration to patients who are overdosed with protamine.
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The need for a portable extracorporeal support system that can be rapidly initiated for various types of cardiopulmonary failure is well known. The authors report on a system consisting of 3/8 inch tubing, a Sci-Med membrane oxygenator, Omnitherm heat exchanger, Biomedicus or Sarns centrifugal pump, portable battery, and oxygen tanks. The system is mounted on a cart for easy mobility and can be primed in 5-10 min. ⋯ There were six survivors (elective PTCA support, three patients; cardiac arrest during catheterization, three patients). Complications included bleeding (15 patients), deep venous thrombosis (three patients), and pump failure (one patient). A portable ECMO system has been developed that allows rapid institution of circulatory support.