Perfusion
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To evaluate the use of extracorporeal membrane oxygenation (ECMO) in patients with Gram-negative or viral sepsis, a survey of ECMO centres comprising the Extracorporeal Life Support Organization was conducted. Data collected from neonatal and paediatric intensive care units included patient demographics, indicators of infection, presence of cardiac instability and respiratory criteria for ECMO. One-hundred-and-seven patients with documented sepsis were divided into survivors and nonsurvivors. ⋯ Although survival is less in septic infants than in infants with traditional respiratory failure placed on ECMO, sepsis should not be a contraindication to the use of ECMO. The parents should be informed of the chances of survival with each type of sepsis or respiratory infection (if known), so that a truly informed decision can be made by the parents. We feel that the additional information regarding Gram-negative and viral sepsis should assist the clinician in this goal.
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Some clinicians place patients in the Trendelenburg position during aortic unclamping to decrease the incidence of microscopic cerebral air embolism. Experimental studies have shown that use of the Trendelenburg position does not prevent air emboli from reaching the brain. Nevertheless, the position can decrease the velocity at which bubbles approach the brain, giving more time for nitrogen in the bubbles to be absorbed. ⋯ The result holds for all usual conditions of CPB. We conclude that absorption does not affect the disposition of air introduced into the arterial circulation. Use of the Trendelenburg position cannot decrease neurologic injury from cerebral air embolism by permitting greater bubble absorption.
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To ascertain current anticoagulation management during neonatal extracorporeal membrane oxygenation (ECMO), a telephone survey was undertaken of all active ECMO (n = 81, 100% response rate) centres in the USA. Hospital policies regarding federal regulations governing laboratory tests [Clinical Laboratory Improvement Amendment (CLIA) 1988] were determined along with specific patient anticoagulation strategies and use of specific activated coagulation time (ACT) equipment. More than 90% of the respondents use the Hemochron device (International Technidyne Corp, Edison, NJ, USA) while the remaining centres use the Hemotec device (Medtronic Hemotec, Inc, Englewood, CO, USA). ⋯ Four out of five respondents reported that heparin dosages were dictated strictly by ACT results, and 63% will temporarily stop heparin administration for high ACT results, bleeding and/or surgery. Approximately one-third of the centres perform proficiency testing of the equipment in compliance with CLIA 1988. In conclusion, there appears to be no consensus regarding commitment to a QC programme among active ECMO centres.
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Comparative Study
Differences in blood activation related to roller/centrifugal pumps and heparin-coated/uncoated surfaces in a cardiopulmonary bypass model circuit.
An in vitro model cardiopulmonary bypass (CPB) circuit consisting ot tubing, oxygenator and venous reservoirs with either a roller or a centrifugal pump, and with either heparin-coated (Carmeda Bioactive Surface, CBAS) or uncoated surfaces, was studied with respect to 'blood activation', using small-scale-based blood volume (450 + 500 ml). Sixteen circuits were tested in each pump group, eight with and eight without heparin-coated surfaces, by circulating heparinized fresh human blood for 72 hours at 30 degrees C. Blood plasma, sampled at defined intervals, was analysed for haemolysis (lactate dehydrogenase and potassium), complement activation (C3bc and C5b-9 (TCC)), complement lytic inhibitors (vitronectin and clusterin), coagulation activation (fibrinopeptide A), granulocyte (lactoferrin and myeloperoxidase) and platelet (beta-thromboglobulin) activation and contaminating endotoxin. ⋯ The two pump types did not differ with respect to these parameters, but the roller pump caused significantly higher increases in plasma LDH and potassium and significantly greater reductions in clusterin and vitronectin than the centrifugal pump. Endotoxin concentration was low at the start and after 24 hours in all groups. These results confirm that heparin-coated CPB surfaces reduce blood activation, and suggest that centrifugal pumps cause less haemolysis and less reduction in lytic complement inhibitors than roller pumps.