Code ICE: Therapeutic Hypothermia

Case Study:

Paramedics are dispatched for a 60-year-old male who is in cardiac arrest. Upon arrival, they initiate ACLS protocol, performing CPR, endotracheal intubation and gaining IV access to administer fluid and cardiac medications. On the cardiac monitor, the patient is in ventricular fibrillation. The automated external defibrillator is used successfully. Upon reassessment, the patient is found in sinus bradycardia with signs of S-T segment elevation myocardial infarction (STEMI) and now has a palpable pulse.

 

Analysis:
At the point of defibrillation, the patient probably had been without a pulse and apneic for at least 15 minutes. However, this is a minimal estimate of the time needed for EMS to be dispatched, arrive at the patient’s side and attempt to resuscitate a patient experiencing an out-of-hospital cardiac arrest (OHCA). During the patient’s “down time” his vital organs were not being perfused. Although the patient experienced return of spontaneous circulation (ROSC), damage has already been done and he may have sustained serious, lasting effects related to the lack of perfusion.
Approximately 30 of 100 cardiac arrest patients may experience ROSC; however, of those 30 survivors, only five will survive to hospital discharge.1 Less than 10% of those surviving will return to normal functioning, suffering from cognitive disabilities associated with anoxic brain injury.With such devastatingly poor statistics, optimal post-resuscitation care is key to improved patient outcomes.

Therapeutic hypothermia (TH), a.k.a. Code ICE, is gaining recognition among EMS and emergency departments worldwide as efficacious post-resuscitation therapy that promotes positive post-arrest outcomes, changing the lives of patients revived from cardiac arrest.

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Gaining Popularity

TH is one of the latest interventions aimed at promoting improved outcomes in post-cardiac arrest patients.

The primary goal of TH is to preserve brain function in the wake of post-resuscitation syndrome, a process in which the resurgence of oxygen to the previously anoxic brain triggers the release of damaging chemicals, such as free radicals.By lowering the body temperature, brain ischemia is decreased and neurological outcomes are improved.4

Once the post-arrest patient is cardiovascularly stabilized, they are assessed for TH eligibility based on stringent inclusion/exclusion criteria. If qualified, the patient’s core temperature is lowered to 32ø C to 34ø C and maintained at this reduced temperature for 12-24 hours.3
The lowering of the body temperature can be accomplished by a variety of methods, depending on the medical environment, ranging from simple ice packs to cold intravenous fluids via intravascular catheter.3
Studies dating back to the 1950’s have shown that TH notably improved survival rates and patient’s quality of life post-arrest.2 A Cochrane meta-analysis based on five TH studies determined that compared with standard normothermia post-arrest care, TH improves the rate of survival to hospital discharge and neurological outcomes in patients who experience ROSC.1
With evidence to support its efficacy, TH is slowly becoming more prevalent in post-arrest care from the field to the ED and on to the critical care setting.

In the Field

EMS providers are the first to provide medical care to OHCA patients. It is the pre-hospital setting where advanced resuscitation techniques may truly impact the patient outcomes.5
Recently, increased focus has been placed on improving the post-resuscitation care that EMS is able to perform when patients experience ROSC, incorporating more advanced and innovative interventions such as TH.
EMS administrators, such as the Maryland Institute for Emergency Medical Services Systems (MIEMSS), have formulated protocols that allow providers to initiate TH in the field. The protocols identify basic inclusion criteria that the patient must satisfy to qualify for TH, which includes: 18 years of age or older, ROSC, comatose state, and cardiovascular stability with a systolic blood pressure greater than 90 mmHg.4
Once it is determined by EMS that the patient is qualified for TH, the providers initiate TH using one of two methods. If resources allow, the patient may be cooled by rapidly infusing lactated ringers solution that has been cooled to approximately 4ø C.4
However, some EMS agencies do not have access to cooled IV fluid. The simpler, cheaper and more readily accessible option for initiating TH protocol in the field is applying cold packs bilaterally to the highly vascular neck, axilla, and femoral groin areas.4
One of the most critical inclusion criteria listed in TH protocol is the ability of the destination hospital to maintain TH after receiving the patient.4 The core temperature must be maintained within the therapeutic range and slowly re-warmed to prevent complications.
The TH process requires extensive training for both ED and intensive care unit staff to execute this intervention successfully. MIEMSS has designated several hospitals throughout Maryland that qualify as Cardiac Intervention Centers (CIC’s), with local hospitals often bypassed to reap the benefits of the advanced care.

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At the Hospital

Hospitals designated as Cardiac Intervention Centers (CIC) have the ability to intervene in cardiac emergencies, which also includes maintaining TH for ROSC patients.6
These patients are typically handed over to ED staff who stabilize the patient and initiate a more sustainable method of TH, depending on the method utilized by EMS. Since this patient is in a very critical state after having been revived from cardiac arrest, they are soon transferred to an ICU where they can be closely monitored.

The sedated, cooled patient must be monitored closely by experienced ICU nursing staff for the 24-hour maintenance period with frequent re-assessment of the patient.5 Temperature monitoring is crucial during this period, as overcooling can cause fatal dysrhythmias.7 A bladder probe is often utilized to closely monitor core temperature and any fluctuations.8The maintenance phase is also the time in which various rare, but serious complications can occur including: hyperglycemia, increased risk for infection, electrolyte imbalances and shivering.8

A very important role of the ICU nurse is that of rewarming the patient, as most patient deaths after TH occur in the rewarming phase.8 Rewarming begins 24 hours after the target temperature is reached and should be done slowly over a period of approximately 12 hours, provided no complications are encountered.5 Methods include passive rewarming by simply removing the cooling method, but may also include active rewarming using warmed blankets.8

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Costs & Benefits

Resuscitation and care of a patient who experiences ROSC is not only financially demanding, but demands many highly trained staff members who are dedicated to a single, critical patient.7
That’s particularly the case for many EMS agencies as such advanced care poses a financial constraint, with limited budgets preventing them from purchasing the temperature-regulated IV fluid coolers needed to adequately perform TH.
The commitment is not possible for all hospitals either, and considering the importance of maintenance of TH once initiated, it could be detrimental for a patient to be transported to an unprepared facility.
Although the literature supports an increased survival rate in patients receiving TH, the medical community has yet to widely accept and implement it.6
But although it is financially burdensome, and although a team effort is required between both pre-hospital and in-hospital providers, the reality is that TH can save lives of patients with previously desolate odds of return to normal life.1
Early TH intervention by EMS personnel and continuity of high quality care by transporting to a CIC is critical in further proving that “Code ICE” promotes improved outcomes for post-arrest patients.
Courtney Utberg is a senior nursing student and Dorothea McDowell Winter is associate professor of nursing, both at Salisbury University in Maryland.

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