ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Because acute liver cell failure is associated with an exceedingly high mortality, liver support has been proposed since the 1950s to improve patient outcome. Early devices, including hemodialysis, hemofiltration, exchange transfusion, plasmapheresis, hemoperfusion, plasma and cross-hemodialysis or cross-circulation, appeared inefficient. Meanwhile, documented results of extracorporeal liver perfusion (ECLP) suggested its superiority over conventional treatment. ⋯ To give the deciding vote and avoid previous pitfalls, trials need to be developed with a larger number of patients based upon statistically significant models with the following characteristics: 1) comprehensive understanding of the acute liver cell failure mechanisms, 2) world wide classification of conditions that require liver support, and 3) a clear definition of treatment success pending patients to LT or recovery without transplantation. There has not yet been conclusive evidence to support the benefits of extracorporeal liver support. We are still waiting for the deciding vote.
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The first intravascular oxygenator and carbon dioxide (CO2) removal device (IVOX), conceived by Mortensen, was capable of removing 30% of CO2 production of an adult at normocapnia with a measurable reduction in ventilator requirements. Through studies of mathematical modeling, an ex vivo venovenous bypass circuit to model the human vena cava, animal models of severe smoke inhalation injury, and patients with acute respiratory failure, the practice of permissive hypercapnia has been established to enhance CO2 removal by IVOX. By allowing the blood pCO2 to rise gradually, the CO2 excretion by IVOX can be linearly increased in a 1:1 relationship. ⋯ Increased surface area with more fibers and enhanced mixing by increased fiber crimping in new prototypes of IVOX significantly increased CO2 removal. Other groups have used alternative designs to address the limited performance of intravascular gas exchange devices. With improved design and patient management, clinically meaningful gas exchange and reduction in mechanical ventilatory support may be achieved during treatment of severe respiratory failure.