ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Extracorporeal membrane oxygenation (ECMO) is widely used in the treatment of respiratory and cardiovascular failure in neonatal patients. The authors present a case of a child with hemoglobin SS disease who was treated with ECMO after acute chest syndrome and acute respiratory distress syndrome developed. They also present data from the Extracorporeal Life Support Organization on this use of ECMO from other centers. ⋯ Patients who might benefit include those with poor ventilation secondary to mucous plugging and barotrauma. The best success with these patients might be anticipated from venoarterial ECMO. Patients with severe cardiac or neurologic deterioration may constitute a group less likely to survive.
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Comparative Study
Clinical heparin coated cardiopulmonary bypass: reduction of systemic heparin requirements for redo cardiac surgery.
The authors compared blood loss, transfusion requirements, and heparin doses for reoperative cardiac surgery using either: a) a Duraflow (Baxter Corporation, Irvine, CA) heparin coated cardiopulmonary bypass (CPB) system or b) standard CPB. Twenty patients underwent redo cardiac surgery while supported with heparin coated CPB, and 17 patients underwent redo cardiac surgery with standard CPB. The following data are presented as mean +/- standard deviation. ⋯ Despite the reduced dose of heparin, the mean activated clotting time in the heparin coated group was similar to the mean activated clotting time of the standard CPB group (577 +/- 98 sec versus 612 +/- 117 sec, p = ns). In conclusion, heparin coated CPB without reduced activated clotting time does not reduce transfusion requirements or blood loss in reoperative cardiac surgery. The heparin coated CPB system allows maintenance of the activated clotting time level despite reduced heparin doses.
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The ability to monitor the match between systemic oxygen delivery and consumption using mixed venous oxygen saturation is an important component of management of critically ill patients. Mixed venous oxygen saturation is a particularly useful parameter in circumstances where systemic oxygen delivery is significantly compromised, such as the acute respiratory distress syndrome. With the advent of venovenous extracorporeal life support (ECLS) in the treatment of this condition, however, accurate measurement of true mixed venous oxygen saturation has not been available, because of this artificial elevation of venous oxygen content. ⋯ The formula has been used in an in vitro model, simulating venovenous ECLS and native venous saturation ranging from 20-72%, with a resulting correlation coefficient between calculated and measured saturation of 0.983 and a gamma intercept of 0.7. Using this new mathematical model, previously unobtainable information about the match of oxygen delivery and consumption in venovenous ECLS is now available. This information will facilitate optimal management of oxygen kinetics in patients during venovenous extracorporeal support.
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Comparative Study
A matched pairs analysis of venoarterial and venovenous extracorporeal life support in neonatal respiratory failure.
It has been suggested that venovenous (VV) extracorporeal life support (ECLS) confers a survival advantage over venoarterial (VA) ECLS. These results have been confounded by differences in patient populations. In this study, a matched pairs comparison of survival and complication rates in neonatal respiratory failure patients managed with VA or VV ECLS was performed. ⋯ Survival is not significantly greater with VV ECLS when patients are matched for degree of respiratory and hemodynamic failure. Hemolysis and cannula kinking are more common with VV ECLS. There is no identified difference in the incidence of intracranial hemorrhage.
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Experimental and clinical use of the intravascular oxygenator (IVOX), an intravenacaval gas exchange device, in acute respiratory failure yielded a CO2 transfer of 40-70 ml/min (approximately 30% of adult CO2 production) at normocapnia. Although significant, this rate of CO2 removal is not clinically useful. To maximize CO2 transfer, given the same gas exchange properties and structure design of the IVOX, the authors analyzed the effects of permissive hypercapnia (stepwise increase in arterial blood pCO2 up to 100 mmHg) and active blood mixing (with an intraaortic balloon pump) on different sizes of IVOX (sizes 7, 8, and 9 mm, surface area 0.21, 0.32, and 0.41 m2, respectively) using a previously established ex vivo circuit to model the human vena cava. ⋯ A 0.42 m2 surface area is associated with an O2 transfer of 80 ml/min without and 107 ml/min with active blood mixing. It is concluded that CO2 removal by IVOX alone is limited by insufficient surface area and the resistance in the blood-surface boundary layer. The combination of permissive hypercapnia, adequate blood flow, and active blood mixing can substantially improve CO2 removal and can therefore achieve clinically significant CO2 removal by intravenacaval gas exchange devices during severe respiratory failure.