Therapeutic Hypothermia Kristi Valdez RN,BSN,CCRN NUR 5200 Introduction to Graduate Nursing

Question Does the effect of therapeutic hypothermia improve mortality and neurological outcomes in cardiac arrest patients compared to normothermia?

Background 300,000 deaths occur annually from cardiac arrest Mortality rate in out of hospital cardiac arrest is more than 90% Of the patients that reach the hospital after cardiac arrest, only 11-48% will have favorable neurological outcome (Laird,2009) Many patients are left in a vegetative state.

Effects of Cardiac Arrest When cerebral perfusion and oxygen delivery stop during cardiac arrest, the oxygen stores are depleted within 20 seconds. As a result electrolyte imbalances, cellular edema, and cell death occur. After ROSC occur, reperfusion injury occurs. This process can last 24-48 hrs. (McKean, 2009, pg. 344) Brain has a small amount of oxygen stores. EEG would show a flat line to patients connected. After oxygen is depleted, the brain turns to anaerobic metabolism. Glucose, ATP are gone within 5 minutes if return of blood flow is not obtained. With reperfusion injury there is a release of free radicals, catecholamine's, cytokines which lead to mitochondria damage and cell death.

Definition of Therapeutic Hypothermia Controlled Induced hypothermia

Effects of Therapeutic Hypothermia Decreasing the cerebral metabolic rate decreases cerebral oxygen consumption Reduces disruptions in the blood-brain barrier and prevents premature cell death AHA recommends patients be cooled to 32-34 degrees Celsius for 12-24 hours. The patient is then rewarmed slowly at 0.5 degrees Celsius per hour (McKean, 2009,pg. 345,352) Cerebral metabolic rate is decreased by 6-7% for each 1 degree Celsius drop in body temperature. It decreases chemical reactions, and decreased neutrophil and macrophil production which reduces the inflammatory response. The goal is to begin induction of hypothermia and achieve target temperature as soon as possible after ROSC-even within 4-6 hrs. The goal should be reach target temperature with 2 hrs. Target is 36.5 degrees Celsius.

Patient Selection Inclusion criteria: 18 yrs. and older GCS < 8 after ROSC Less than 6 hours from ROSC and start of cooling SBP>90 mm/hg Intubated with Mechanical ventilation Exclusion criteria: Preexisting bleeding or coagulopathy Trauma Recent major surgery Known systemic infection/sepsis

Types of hypothermia treatments Non-invasive hypothermia Invasive hypothermia Ice packs Fans Cooling blankets Iced intravenous fluids Intravascular catheters

Current Evidence Author Sample Research Methodology Findings Bernard (1997) 22 adult patients Prospective Study Good neurological outcome : 11/22 in hypothermia 3/22 in normalthermia Yanagawa (1998) 28 adult patients Prospective study Survival: 7/13 in hypothermia 5/15 in normalthermia Good neurological outcome: 3/13 in hypothermia 1/15 in normalthermia (Collins, Samsworth,2008, pg. 146)

Current Evidence Author Sample Research Methodology Findings Bernard (2002) 77 adult patients RCT Survival: 21/43 in hypothermia 11/34 in normalthermia Good neurological outcome: 21/43 in hypothermia 9/34 in normothermia HACA study group (2002) 275 adult patients 6 month mortality: 41% in hypothermia, 55% in normalthermia Good neurological outcome: 55% in hypothermia 39% in normalthermia (Collins, Samsworth,2008, pg. 146)

Conclusion After reviewing current evidence, therapeutic hypothermia does improve neurological and mortality outcomes compared to normalthermia.

References Calver, P., Braungardt, T., Kupchik, N., Cutler, C., & Jensen, A. (2005). The big chill: improving the odds after cardiac arrest. Rn, 68(5), Laird, P. (2009). Induced hypothermia for neuroprotection following cardiac arrest: a review of the literature. Internet Journal Of Advanced Nursing Practice, 10(2), 4. McKean, S. (2009). Induced Moderate Hypothermia After Cardiac Arrest. AACN Advanced Critical Care, 20, 343-355. Retrieved from www.aacn.org Collins, T., & Samworth, P. (2008). Therapeutic hypothermia following cardiac arrest: a review of the evidence. Nursing In Critical Care, 13(3), 144-151. Zeitzer, M. (2005). Inducing hypothermia to decrease neurological deficit: literature review. Journal Of Advanced Nursing, 52(2), 189-199. doi:10.1111/j.1365-2648.2005.03574.x Clumpner, M., & Mobley, J. (2008). Raising the dead: prehospital hypothermia for cardiac arrest victims may improve neurological outcome and survival to discharge. EMS Magazine, 37(9), 52-60.