The Relationship Between Therapeutic Hypothermia on Neurological Outcome and Survival Rate in Patients After Cardiac Arrest

Title: The relationship between therapeutic hypothermia on neurological outcome and survival rate in patients after cardiac arrest

Complete neurological recovery after cardiac arrest is uncommon as decent cerebral recoveries were only seen in 11%-48% of cases (Holzer & Behringer 2008). Successful resuscitation after cardiac arrest may lead to harmful chemical processes resulting in delayed necrosis and programmed brain cell death (Holzer & Behringer 2008). These effects results from perfusion failure and re-oxygenation damage the neuronal tissues. Therapeutic hypothermia (TH) which is the inducement of body temperature ranges below normal homoeothermic levels by cooling to 32-34oC for 24 hours, is able to improve neuronal injury (Testori et al. 2011). TH decreases neuronal cell death by preventing lipid peroxidation and reduce oxygen requirements without affecting blood flow hence, improving the survival rate of these individuals (Holzer & Behringer 2008). This work will focus on the relationship between TH on neurological and subsequently survival improvement in cardiac arrest survivors through evidence of its effectiveness in various survivor groups. Five article summaries are included. Articles 1 and 2 examine the effects of TH on neurological outcomes. Articles 3 and 4 investigate the neurological outcome after TH specifically in ventricular fibrillation (VF) and non-VF induced cardiac arrest. Article 5 predicts clinical factors in improving neurological outcome in patients treated with TH. Ratings of each article were conducted with 10 being the most relevant for literature review.

Therapeutic hypothermia improves the neurological outcome in cardiac arrest survivors. More research on the effects of TH on survival rate is required as contradictory survival outcomes were observed in studies conducted by Bro-Jeppesen et al. (2009) and Testori et al. (2011). Further work regarding this topic is required in developed countries specifically in Europe where the incidences of cardiac arrest are relatively high (Bro-Jeppesen et al. 2009). The proposed research question is the effects of therapeutic hypothermia on neurological outcome and survival rate in individuals after cardiac arrest in Europe.

Title of primary article 1

The impact of therapeutic hypothermia on neurological function and quality of life after cardiac arrest

The incidence of cardiac arrest in Copenhagen is high with only a survival rate of 6% after 30 days. Bro-Jeppesen et al. (2009) conducted a research to investigate the neurological implications of therapeutic hypothermia (TH) and survival of comatose patients of out-of-hospital-cardiac-arrest (OHCA). 79 individuals receiving TH (intervention group) were compared with 77 non-TH patients from OHCA (control group) through the assessment of Cerebral Performance Category (CPC) and Mini Mental State Examination (MMSE). The results showed that 97% of patients in the intervention group had CPC 1 or 2, showing no or minor cognitive incapacity compared to 71% from the control group. As for the MMSE, the mean score of the intervention group was 28.5±1.2 compared to 27.9±2.9 in the control group with 30 as the maximum score and a score of <24 indicating reduced cognitive function. The survival rate after 30 months was 57% from the intervention group and 56% from the control group. In conclusion, TH improves the cerebral performance and cognitive function of OHCA patients but has no significant effect on the survival rate.

Rating: 8/10. The article has relevant information and clear statistical results.

Title of primary article 2

Long-term neurological outcome after cardiac arrest and therapeutic hypothermia

Cardiac arrest which cuts the supply of oxygen to the brain results in brain tissue damage. Cronberg et al. (2009) conducted a research to study the neurological conditions after cardiac arrest in patients treated with therapeutic hypothermia (TH). 43 patients who received TH from three hospitals were tested for cognitive function after six months using methods such as the Cerebral Performance Category (CPC) and the Frontal Lobe Assessment Battery (FAB). The results showed that none of the patients were suffering in a vegetative condition as 96% of individuals had a score of 1-2 on CPC with no or minor cerebral disability and only one patient needing full-time assistance. One patient suffered from seizures while another suffered from myclonic jerks, which reduced over time. Furthermore, 37.5% of the individuals had frontal lobe impairment while one-third had fair to serious memory problems. Minor depression and anxiety as well as the occurrence of insomnia on a recurring basis were also reported. In conclusion, minor cerebral impairment is seen in TH treated patients after cardiac arrest but have little effect on the daily