ASAIO transactions / American Society for Artificial Internal Organs
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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.
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After satisfactory development and testing of a polyurethane 14 Fr double lumen catheter, we used this device for venovenous extracorporeal life support in neonates who had respiratory failure. This catheter was designed for single site cannulation of the internal jugular vein, thereby sparing the carotid artery from ligation. Cannulation was successful in 17 of 21 neonates, with 15 successful venovenous runs, whereas 2 of the 17 patients were converted to venoarterial bypass because of inadequate support. ⋯ All 15 patients survived, and exploration of the cannulation site for bleeding was required in three patients. Preoxygenator pressure, recirculation of oxygenated blood, and hemolysis were all within acceptable levels during each run. Venovenous extracorporeal life support with the double lumen catheter can replace venoarterial access in most cases of neonatal respiratory failure.
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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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To perform low blood flow extracorporeal CO2 removal (ECCO2R), the authors developed a device for extracorporeal circulation (ECC) equipped with a dialyzer for the elimination of CO2 as bicarbonate. The major problem with this method was the decrease in blood pH. To control blood pH and clarify the limit of CO2 elimination using this method, a study with apneic dogs was performed. ⋯ The CO2 was converted to bicarbonate using systemic infusion of trihydroxy-methylamino methane (THAM), and the generated bicarbonate was removed by hemodialysis. Blood flow rate in the ECC was 15 ml/kg/min, and the duration of ECC was 5 hr. During ECC, the hemodynamic parameters of the dogs were stable, and the PaCO2 remained at about 90 mmHg with a PaO2 above 350 mmHg; CO2 elimination from the airway was negligible.