Prevent blood clots during Therapeutic Hypothermia

Blood clots during therapeutic hypothermia may be prevented by the use of temperature dependent drug:

Therapeutic Hypothermia, a medical treatment which helps in lowering the patient’s body temperature also helps in reducing the risk of ischemic injury to the tissue following a period of insufficient blood flow. Sometimes insufficient blood flow is seen due to cardiac arrest or due the occlusion of artery by an embolism, as observed in the case of strokes. Therapeutic Hypothermia may be caused due to invasive means, in which a catheter is placed in the inferior vena cava via femoral vein, or through non-invasive means, usually employing chilled water blankets in direct contact with the patient’s skin.

It is been observed that patients those who were at a risk for ischemic brain injuries showed better results when treated with therapeutic hypothermia. In order to prevent blood clotting during therapeutic hypothermia, scientist have come up with a fresh drug that can be charged at cool temperature and turned off at warm ones, as per the research demonstrated at the American Heart Association’s Arteriosclerosis, Thrombosis, and Vascular Biology Annual Conference 2010.

Karlheinz Peter, M.D., Ph.D., added “we employed biotechnology to create a modern intelligent drug” also a leading author of the study and associate director of Baker IDI Heart & Diabetes Institute in Melbourne, Australia. He also added “This drug is tailored for preventing clots during therapeutic hypothermia and for minimizing bleeding problems especially after rewarming”.

The use of therapeutic hypothermia by doctors is mainly observed when heart temporarily stops pumping either spontaneously (as in the case of cardiac arrest) or during cardiovascular surgery. In order to carry out this procedure in a systematic manner, doctor suppresses patients internal body temperature, as it prevent organ injury as well as brain damage, by reducing metabolic rate and oxygen requirements.

It has been observed that new drugs works best only at cooler temperature by inhibiting the activity of platelets, cells that bind together to stop bleeding. Researchers, in Mouse and Human blood samples, clearly demonstrated that the experimental drug bound to the platelets and prevent them from clumping together at cool temperature (22º C or 71.6º F). It is also been observed that as soon as the researchers increased the temperature from cooler to normal (37º C or 98.6º F), the anti-platelet action is stopped.

Peter shared “Our idea was to develop a reagent that is highly active at the moment it is really needed ─ when patients are at low temperature ─ and that loses its function when it is no longer needed ─ when patients are rewarmed,”.

Peter along with his partners at Baker and Emory University in Atlanta, Ga., used recombinant DNA technology to fuse temperature-depended protein with protein that inhibits platelets activity. The first part of this new protein is similar to the protein elastin, that gives skin and other organs their flexibility and is known to change shape in response to temperature changes. The second part, antibody portion of this combined protein inhibits platelet activity by blocking the receptors that normally enable these cells to clot together to heal an injury.

Since decades, healthcare practitioner are familiar with therapeutic hypothermia’s benefits, but its usage in cardiac patience is considered as a recent development. In the year 1950, doctors started using this treatment for cardiac surgery, including valve and bypass surgery. Basically, therapeutic hypothermia is used during surgical repair of structure cardiac defects in infants, adults, and children. Hence, cardiac hypothermic surgery is associated with a substantial risk of clotting.

In order to get rid of this serious ailment, “anti-clotting drug” is considered as a standard part of therapeutic hypothermia. The main pull back for current anti-clotting medicine continues even after body temperature is increases to normal level, sometimes leads to excessive post-surgical bleeding, said researchers. More specifically, the new combined protein not only prevent blood clot formation during cooling but also also prevent bleeding problems after rewarming.

After detailed clinical studies, the American Heart Association in October 2002 demanded that therapeutic hypothermia should also be used to treat patients suffering from cardiac arrest. In order to lower the patient’s internal body temperature, doctors make use of cooling blankets, ice packs, or other substances. By the use of above mentioned therapy doctors can increase the survival rate and decrease long term disability, though there may be a chance of blood clot.

To prove that the novel temperature-dependent drug also protects patients suffering from this type of hypothermia used for the protection of the brain in patients after cardiocirculatory arrest, further detailed studies required to determine the level of platelets inhibition at temperatures such as 32º C to 34ºC (89.6 º F to 93.2 º F), said peter.

Co-contributors are: Denijal Topcic, Ph.D.; Carolyn A. Haller, Ph.D; Wookhyun Kim, Ph.D.; Andreas Straub, M.D.; Fu Jia, M.D.; and Elliot L. Chaikof, M.D., Ph.D. Author disclosures are on the abstract.

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