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==Clinical trials of blood substitutes==
==Clinical trials of blood substitutes==

Since blood transfusions are often most critically needed in trauma situations, where obtaining [[informed consent]] is either difficult, impossible, or a barrier to providing lifesaving care, the ethics of clinical trials for these products are difficult. In the United States, these trials are performed under a specific exemption from requirements for informed consent.<ref>[http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=50.24 FDA > CDRH > CFR Title 21 Database Search]</ref>


Nominally, the community where blood substitutes will be used in clinical trials is informed, and wristbands or other clear markers are distributed so that a person can "opt out" of the trial. The concept that a person could be involved in experimentation on humans without consent is controversial.<ref>[http://mesh.medill.northwestern.edu/mnschicago/archives/2006/08/results_of_cont.html Medill News Service : Chicago - Results of controversial blood substitute trial crucial for Northfield Labs]</ref>
Nominally, the community where blood substitutes will be used in clinical trials is informed, and wristbands or other clear markers are distributed so that a person can "opt out" of the trial. The concept that a person could be involved in experimentation on humans without consent is controversial.<ref>[http://mesh.medill.northwestern.edu/mnschicago/archives/2006/08/results_of_cont.html Medill News Service : Chicago - Results of controversial blood substitute trial crucial for Northfield Labs]</ref>
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In 2008, blood substitute production was halted temporarily when the [[Journal of the American Medical Association]] studied outcomes of transfusions given to trauma patients without proper consent<ref>Davis, R. (2008, April 28). Study: Blood substitute increases risk of death. Retrieved December 2, 2010, http://www.usatoday.com/news/health/2008-04-28-fake-blood-risks_N.htm</ref>. The products yielded a 30% increase in the risk of death and about a three-fold chance of having a heart attack of for the recipients. More than 3,711 patients were tested in sixteen studies using five types of artificial blood<ref>Stein, R. (2008, April 29). FDA Faulted for Approving Studies of Artificial Blood. Retrieved December 2, 2010, http://www.washingtonpost.com/wp-dyn/content/article/2008/04/28/AR2008042801025.html</ref>. The FDA permits artificial blood transfusions to occur across its nation without informed consent under a special rule. [[Public Citizen]] sued the [[FDA]] to attain information on the duration of these studies which were found to have been conducted from 1998 until 2007.
In 2008, blood substitute production was halted temporarily when the [[Journal of the American Medical Association]] studied outcomes of transfusions given to trauma patients without proper consent<ref>Davis, R. (2008, April 28). Study: Blood substitute increases risk of death. Retrieved December 2, 2010, http://www.usatoday.com/news/health/2008-04-28-fake-blood-risks_N.htm</ref>. The products yielded a 30% increase in the risk of death and about a three-fold chance of having a heart attack of for the recipients. More than 3,711 patients were tested in sixteen studies using five types of artificial blood<ref>Stein, R. (2008, April 29). FDA Faulted for Approving Studies of Artificial Blood. Retrieved December 2, 2010, http://www.washingtonpost.com/wp-dyn/content/article/2008/04/28/AR2008042801025.html</ref>. [[Public Citizen]] sued the [[FDA]] to attain information on the duration of these studies which were found to have been conducted from 1998 until 2007.The FDA permits artificial blood transfusions across its nation without informed consent under a special exemption from requirements of informed consent during traumatic care.<ref>[http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=50.24 FDA > CDRH > CFR Title 21 Database Search]</ref>




Revision as of 16:39, 3 December 2010

A Blood substitute (also called artificial blood or blood surrogates) is a substance used to mimic and function blood. Although it contains no blood components such as red blood cells, white blood cells, platelets or plasma, it removes carbon dioxide and transfers oxygen throughout the body until bone marrow is capable of producing more red blood cells[1]. The main categories of blood substitutes are hemoglobin-based oxygen carriers (HBOCs) and perfluorocarbon-based oxygen carriers (PFBOCs)[2].

History

After William Harvey discovered blood pathways in 1616, many people tried to use fluids such as beer, urine, milk, and animal blood as blood substitute[3].The demand for more blood substitutes began during the Vietnam War as wounded soldiers were unable to be treated at hospitals due to blood shortages.


Major worldwide blood shortages have led scientists to synthesize and test artificial blood[4]. Infected blood is a major problem for many countries.Each year 10-15 million units of blood are transfused without being tested first for HIV and hepatitis[5].The largest cause of new HIV infections in Nigeria comes from transfused blood.


Volume expanders

Main article: Volume expander

A volume expander is a type of blood substitute that has the function of providing volume for the circulatory system. It may be used for fluid replacement.

Volume expanders are widely available and are used in both hospitals and first response situations by paramedics and emergency medical technicians.

There are two main types of volume expanders; crystalloids and colloids. Crystalloids are aqueous solutions of mineral salts or other water-soluble molecules. Colloids contain larger insoluble molecules, such as gelatin; blood itself is a colloid.

Oxygen-carrying substitutes

Main article: Oxygen-carrying blood substitute

The use of oxygen-carrying blood substitutes is often called oxygen therapeutics.

The initial goal of oxygen carrying blood substitutes is merely to mimic blood's oxygen transport capacity. There is additional longer range research on true artificial red and white blood cells which could theoretically compose a blood substitute with higher fidelity to human blood.

Unfortunately, oxygen transport (one function that distinguishes real blood from other volume expanders) has been very difficult to reproduce. Oxygen therapeutics are in clinical trials in the U.S. and Europe, Hemopure is available in South Africa.

Examples: Hemopure, Oxycyte, Oxygent, PolyHeme and Perftoran. Oxygen therapeutics are in turn broken into two categories based on transport mechanism: perfluorocarbon based, and hemoglobin based.

Clinical trials of blood substitutes

Nominally, the community where blood substitutes will be used in clinical trials is informed, and wristbands or other clear markers are distributed so that a person can "opt out" of the trial. The concept that a person could be involved in experimentation on humans without consent is controversial.[6]


In 2007, scientists from the chemistry department of the University of Sheffield created artificial blood from plastic[7]. Unlike donated blood which has a shelf life of 35 days, this blood lasted for additional days without needing refrigeration. This blood was developed for five years so that it could be condensed into a paste form at room temperature and only required water to return to its liquid state. This plasticized blood mimicked hemoglobin because it held iron and could bind to oxygen.


In 2008, blood substitute production was halted temporarily when the Journal of the American Medical Association studied outcomes of transfusions given to trauma patients without proper consent[8]. The products yielded a 30% increase in the risk of death and about a three-fold chance of having a heart attack of for the recipients. More than 3,711 patients were tested in sixteen studies using five types of artificial blood[9]. Public Citizen sued the FDA to attain information on the duration of these studies which were found to have been conducted from 1998 until 2007.The FDA permits artificial blood transfusions across its nation without informed consent under a special exemption from requirements of informed consent during traumatic care.[10]


Scientists from the experimental arm of the Pentagon of United States of America began creating artificial blood to transport blood to remote areas and transfuse blood to wounded soldiers more quickly in 2010[11]. The blood is made from the hematopoietic stem cells removed from umbilical cord between the mother and fetus of humans after birth using a method called blood pharming. Pharming has been used in the past on animals and plants to create medical substances in large quantities. Each cord can produce approximately 20 units of blood or three blood transfusions. The blood is being produced for the Defense Advanced Research Projects Agency by Arteriocyte. The Food and Drug Administration has examined and approved the safety of this blood from previously submitted O-negative blood. Using this particular artificial blood will reduce the costs per unit of blood from $5,000 to equal or less than $1,000[12]. This blood will also serve as a blood donor to all blood types. Pharmed blood may be used in human trials in 2013.

See also

References

  1. ^ Schimmeyer, S. (2002, November 1). illumin: article: The Search for a Blood Substitute. Retrieved December 2, 2010, http://illumin.usc.edu/article.php?articleID=62
  2. ^ Brown University Division of Biology and Medicine. (2006). History. Retrieved December 3, 2010, http://biomed.brown.edu/Courses/BI108/2006-108websites/group09artificialblood/Pages/history.htm
  3. ^ Brown University Division of Biology and Medicine. (2006). History. Retrieved December 3, 2010, http://biomed.brown.edu/Courses/BI108/2006-108websites/group09artificialblood/Pages/history.htm
  4. ^ Schimmeyer, S. (2002, November 1). illumin: article: The Search for a Blood Substitute. Retrieved December 2, 2010, http://illumin.usc.edu/article.php?articleID=62
  5. ^ Brown University Division of Biology and Medicine. (2006). Home Page. Retrieved December 3, 2010, http://biomed.brown.edu/Courses/BI108/2006-108websites/group09artificialblood/index.htm
  6. ^ Medill News Service : Chicago - Results of controversial blood substitute trial crucial for Northfield Labs
  7. ^ University Of Sheffield (2007, May 14). Scientists Develop Artificial Blood. ScienceDaily. Retrieved December 2, 2010, http://www.sciencedaily.com¬ /releases/2007/05/070512113724.htm
  8. ^ Davis, R. (2008, April 28). Study: Blood substitute increases risk of death. Retrieved December 2, 2010, http://www.usatoday.com/news/health/2008-04-28-fake-blood-risks_N.htm
  9. ^ Stein, R. (2008, April 29). FDA Faulted for Approving Studies of Artificial Blood. Retrieved December 2, 2010, http://www.washingtonpost.com/wp-dyn/content/article/2008/04/28/AR2008042801025.html
  10. ^ FDA > CDRH > CFR Title 21 Database Search
  11. ^ Edwards, L. (July 13, 2010). Artificial blood developed for the battlefield. Retrieved November 30, 2010 http://www.physorg.com/news198221258.html
  12. ^ Edwards, L. (July 13, 2010). Artificial blood developed for the battlefield. Retrieved November 30, 2010 http://www.physorg.com/news198221258.html
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