Emergency treatment of cardiac arrest generally involves manual artificial breathing to facilitate oxygen circulation to the brain, as well as chemical and electrical induction of the heart to reinstate its normal beating. Such emergency procedures mainly aim to provide a way to reoxygenate the brain and to save it from further irreversible damage. Consequently, reoxygenation also generates free radicals that are responsible in creating a post-resuscitation syndrome, which is characterized by necrosis of different tissues of the patient.
The observation that tissues survive at particular hypothermic settings has been evaluated as a promising emergency treatment for cardiac arrest (http://www.rnweb.com/rnweb/article/articleDetail.jsp?id=158218). Hypothermia involves subjecting the body of an individual in a temperature that is below the normal physiologic temperature. The effect of hypothermia in protecting the brain from severe and irreversible damage during the non-oxygenated state of cardiac arrest is currently being evaluated, after successful results in dog models. Several investigations have been conducted on the direct and immediate positive effect of hypothermia in cardiac arrest patients.
A prospective clinical trial involving the use mild resuscitative cerebral hypothermia in 27 cardiac arrest patients for at least 24 hours showed that hypothermia treatment is reliable and safe (Zeiner et al., 2000). The procedure involved cooling of the entire body, including the head, resulting in a lowering of body temperature within 62 minutes after commencement of hypothermia treatment.
It is interesting to note that no further complications associated with the cardiac arrest were observed after the application of hypothermia treatment. In a separate investigation, 55% of cardiac arrest patients treated with hypothermia was observed to show positive responses to the treatment, as well as a decrease in the mortality rate 6 months after hypothermia treatment, suggesting that hypothermia treatment favors the prevents deleterious brain damage and death among cardiac arrest patients (HACASG, 2002).
However, there are also certain issues with regards to the application of hypothermia in cardiac arrest patients that remains unclear and doubtful. One of these includes the inclusion and exclusion criteria that will determine whether a particular patient will benefit from such treatment (Skowronski, 2005). This comment is mainly based on the need for personalized treatment of patients because of the recent observation of inter-individual variations in the response to specific treatments.
Such observation explains subtle yet significant differences that should be addressed during medication, diagnosis and testing of patients for any type of illness. With regards to cardiac arrest emergency treatments, it is of prime importance that a patients unique physiological, genetic, metabolic and cardiac profile be determined first before subjecting him to hypothermic conditions. However, this profiling may also pose to be a hindrance during emergency treatment because the survival of the cardiac arrest patient mainly depends on the speed of administration of the treatment to the patient.
Specific risks have already been identified to be associated with hypothermia treatment of cardiac arrest patients (http://www.sca-aware.org/sca-treatment.php#treatment3). The exposure of the patient to cold temperatures at a prolonged duration may cause bleeding or hemorrhage in specific organs of the patients because the cold temperature slows down the blot clotting capability of the platelets. In addition, a cardiac patient treated with hypothermia may suffer from infection because the immune system is also inhibited by prolonged cold temperatures.
An alternative treatment that is parallel to hypothermia has been proposed to be as effective as hypothermia, and possibly much safer than the more radical hypothermic exposure of the cardiac patient to low temperature levels. The alternative treatment involves intravenous introduction of ice-cold fluid to the patient using automated cooling equipment (Bernard, 2005). Such settings provide the healthcare personnel complete control over the temperature of the intravenous fluid, which plays a vital role in the emergency treatment of the cardiac arrest patients.
Until sufficient clinical investigatory information has been collected from comprehensive and comparative studies on the risks and benefits of hypothermia treatment on cardiac arrest patients, it is imperative that healthcare personnel be cautious in administering such rapid and radical treatment to cardiac arrest patients.
There have been active requests from the medical research field that such investigations will provide a better understanding of the mechanisms and pathophysiological routes that are involved in the exposure of the body, most specifically the brain and the rest of the central nervous system, to cold temperature during those critical non-oxygenated states (Bernard, 2004).
Bernard (2004): Therapeutic hypothermia after cardiac arrest: Hypothermia is now standard care for some types of cardiac arrest. Med. J. Austral. 181(9):468-469.
Bernard SA (2005): Hypothermia improves outcome from cardiac arrest. Crit. Care Resusc. 7:325-327.
Hypothermia After Cardiac Arrest Study Group (HACASG) (2002): Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest. N. Engl. J. Med. 346(8):549-556.
Skowronski GA (2005): Therapeutic hypothermia after cardiac arrest- Not so fast. Crit. Care Resusc. 7:322-324.
Zeiner A, Holzer M, Sterz F, Behringer W, Scho¨rkhuber W, Mu¨llner M, Frass M, Siostrzonek P, Ratheiser K, Kaff A and Laggner AN (2000): Mild resuscitative hypothermia to improve neurological outcome after cardiac arrest: A clinical feasibility trial. Stroke 31:86-94.
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