Therapeutic Hypothermia (Th): Literature Review

Therapeutic hypothermia (TH): Literature review Therapeutic hypothermia (TH) is a form of medical treatment designed for severe and traumatic medical situations, such as resuscitating patients with cardiac conditions as well as treating traumatic brain injuries resulting from impact and/or stroke. This paper will provide a literary review of various types of recent studies on the efficacy of the TH technique. Therapeutic hypothermia: Literature review of evidence, tools, and results The need for improved, immediate treatment of cardiac patients has long been manifest to the medical community.

According to Eisenburger et al. (2001) in the study "Therapeutic hypothermia after cardiac arrest: Current opinion in critical care" resuscitation of cardiac patients is required in more than "190 people per day in the United States and 50 to 66 per 100,000 per year in Europe" (Eisenburger 2001: 184). TH is often cited as a potentially useful technique to improve survival rates of cardiac patients. However, most studies of therapeutic hypothermia have been relatively small. A study by Tran et al.

(2010) entitled "Use of mild therapeutic hypothermia to treat cardiac arrest" involved only a comparison of 77 patients from four different Australian hospitals. Tran (2010) concluded that the use of TH on cardiac patients could improve both short-term neurologic recovery and long-term survival. Tran justified the limited size of the research population because of the study's diversity of cardiac patients, although he did note that further study was required.

The fact that the procedure "decreases energy use and oxygen consumption in the brain and heart and glucose consumption during the early stages of cardiac arrest" and showed improved outcomes suggests that the technique could be valuable (Tran et al. 2010). Hovdenes, J. et al. (2007)'s study, "Therapeutic hypothermia after out-of-hospital cardiac arrest: experiences with patients treated with percutaneous coronary intervention and cardiogenic shock" also supported the use of therapeutic hypothermia.

This study involved 50 patients at a Norwegian hospital and, regardless of whether the therapy was administered at a local or referring hospital, neurological and survival outcomes were improved in patients that received TH. Another Scandinavian study, by Oksanen et al. (2007) in Finnish intensive care units was even more promising. Instead of comparing the improvement of a small population to the general population, Oksanen (2007) conducted a larger, cross-sectional study, comparing the improvement rates at 20 hospitals that used TH, a total of 407 affected cardiac patients that received the treatment.

"The proportion of cardiac arrest patients treated with TH had increased from 4% in 2002 to 28% in 2005. The incidence of cardiac arrest patients admitted to ICUs was 15/100,000 inhabitants/year. The use of TH varied in different areas of the country from 3.4 to 5.0/100,000 inhabitants/year. in-hospital mortality of TH patients was 32.7% and increased from 13.2% in age group" (Oksanen 2007: 866).

In the Oksanen study, younger patients treated with TH had a significantly better survival rate: the larger numbers in this study and the meticulous demographic data allowed for a more refined conclusion than some other TH studies. However, this study merely demonstrated a correlation between the increased use of TH and improved outcome rates of cardiac patients at the hospitals in question, rather than demonstrated a clear cause-and-effect relationship. Literature reviews of TH studies on wider populations of patients have been less promising. Sayre et al.

(2010) in the Ohio Department of Public Safety study "Effect of pre-hospital therapeutic hypothermia on neurologic outcome following sudden cardiac arrest" conducted a review of 450 resuscitations in medical literature. Sayre et al. (2010) found that TH caused neither a negative -- nor a positive -- improvement in patient survival or neurological improvement.

The one positive finding for advocates of the technique is that the Sayre study does validate TH safety, a finding also confirmed by an implementation study by Busch (2006) "Rapid implementation of therapeutic hypothermia in comatose out-of-hospital cardiac arrest survivors." This study found that a simple, external cooling protocol could be implemented easily "overnight in any system already treating post-resuscitation patients" and had an 89% success rate in reaching optimal temperature -- however, only 27 patients made up the study (Busch 2006: 1277).

A more recent, 2009 study by Castren (2009) "Scandinavian clinical practice guidelines for therapeutic hypothermia and post-resuscitation care after cardiac arrest" found the TH technique ineffective because even experienced physicians were unaware of "optimal target temperature, duration of cooling and rewarming time" and were only able "to predict the clinical outcome correctly in only 52% of the patients" (Castren 2009: 280). Supporters of the therapy admit that a lack of knowledge and training has made widespread implementation of TH problematic. In one Canadian study by Kenneday, J. et al.

(2010),"The use of induced hypothermia after cardiac arrest: a survey of Canadian emergency physicians," only one half of Canadian physicians were found to have used TH in practice. Poor training rather than ineffectiveness of the technique was blamed. Controversy regarding the effectiveness of TH in regarding brain injuries is even more controversial. A study by Marion, et al. (1997) "Treatment of Traumatic Brain Injury with moderate hypothermia" of 82 patients concluded, based upon neurological recovery rates of 82 patients with similar injuries that hypothermia may limits metabolic processes that can exacerbate TBI.

But a 2010 study of stroke patients by Hemmen, "Intravenous thrombolysis plus hypothermia for acute treatment of ischemic stroke (ICTuS-L)" found little improvement. Conclusion: Nursing strategy recommendations and importance of using a theoretical model The larger studies of TH tend to be less conclusive regarding the technique's effectiveness. This should not be surprising, given that, because of the limited available test population, a tightly-controlled experimental study can be difficult to conduct.

The absence of comparative longitudinal data and very large population studies of patients with or without TH treatment may also be partially due to a lack of physician training in the technique and thus its lack of implementation. To date, the most sweeping review of the data has been that of Sayre (2010) who found neither help nor harm were conveyed by the therapy's use.