Critical care clinics
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Nanobiotechnology is the assembling of biological molecules into nanodimension complexes. This has been used for the preparation of polyhemoglobin formed by the assembling of hemoglobin molecules into a soluble nanodimension complex. New generations of this approach include the nanobiotechnological assembly of hemoglobin, catalase, and superoxide dismutase into a soluble nanodimension complex. ⋯ Another recent novel approach is the assembling of hemoglobin and fibrinogen into a soluble nanodimension polyhemoglobin-fibrinogen complex that acts as an oxygen carrier with platelet-like activity. This is potentially useful in cases of extensive blood loss requiring massive replacement using blood substitutes, resulting in the need for the replacement of platelets and clotting factors. A further step is the preparation of nanodimension artificial red blood cells that contain hemoglobin and all the enzymes present in red blood cells.
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Critical care clinics · Apr 2009
Randomized Controlled Trial Multicenter StudyThe USA Multicenter Prehosptial Hemoglobin-based Oxygen Carrier Resuscitation Trial: scientific rationale, study design, and results.
Human polymerized hemoglobin (PolyHeme) is a universally compatible oxygen carrier developed for use when red blood cells are unavailable and oxygen-carrying replacement is needed to treat life-threatening anemia. This multicenter phase III trial assessed survival of patients resuscitated with a hemoglobin-based oxygen carrier starting at the scene of injury. ⋯ Although there were more adverse events in the PolyHeme group compared with control patients receiving blood, the observed safety profile is acceptable for the intended population. The benefit-to-risk ratio of PolyHeme is favorable when blood is needed but is not available or an option.
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Critical care clinics · Apr 2009
Review Comparative StudyComparison of Hemoglobin-based oxygen carriers to stored human red blood cells.
Since the inception of allogeneic blood transfusion, the search for an alternative to the use of stored packed red blood cells has been underway. Over the last 10 years, modified hemoglobin solutions in the form of hemoglobin-based oxygen carriers (HBOCs) have made significant strides toward becoming clinically available and useful. Although HBOCs are not yet ready for regular use in the clinical arena, this may change in the near future as HBOC products continue to improve and as the elucidation of the mechanisms of any adverse effects becomes clearer. In the mean time, we must further the development of alternative strategies for the "hemoglobin bridge" so desperately needed by many critically ill patients.
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Critical care clinics · Apr 2009
ReviewOxygen therapeutics: perfluorocarbons and blood substitute safety.
Current demands over the blood supply in developed and developing nations will compound over time. Red cell substitutes have a promising value proposition for transfusion services, because they hold the promise of increasing the availability of blood products and removing donor and contamination safety risks. In this article, the authors note that existing products suffer from critical shortcomings such as vasoactivity; they also point out that substitutes not based on human blood introduce potentially more complex safety hurdles. The authors discuss the attributes of an ideal blood substitute, and the mechanism and current status of perfluorocarbons; they also review the shortcomings of all oxygen therapeutic products in development today.
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Critical care clinics · Apr 2009
ReviewPotential uses of hemoglobin-based oxygen carriers in critical care medicine.
Hemoglobin-based oxygen carriers (HBOCs) were initially developed to provide an alternative to blood transfusion. With the realization that hemoglobin solutions not only are red blood cell substitutes but also have a number of additional properties, including hemodynamic effects related to their oncotic and nitric oxide-scavenging effects, the broader concept of "hemoglobin therapeutics" was born. Promising effects on oxygen transport and the microcirculation need to be confirmed, and the results of studies with newer, second-generation HBOCs are eagerly awaited. In the meantime, possible adverse effects need to be carefully evaluated before HBOCs can be widely used in the ICU, emergency room, or prehospital setting.