Cooling Targerting Temperature Management Use

• Learn the history of targeting temperature management (TTM) as a method of lowering physiological stress after cardiac arrest and improving neurological outcomes.
• Know the common goals of targeting temperature management and other potential clinical applications, such as hypoxic-ischemic encephalopathy or stroke.
• Understand the risks associated with targeting temperature management including rebound hyperthermia or increased risk of infection.

One of the primary determinants of survival and long-term functional health post-cardiac arrest is cardiopulmonary resuscitation (CPR) and an external defibrillator for a shockable rhythm. Targeted temperature was once one of the main therapeutic strategies for improving neurological outcomes in post-resuscitation care, but recent clinical trials have muted the days of aggressive cooling because of the higher incidence of systemic complications.

The History of Targeting Temperature Management

Targeted temperature management (TTM) refers to therapeutic hypothermia or protective hypothermia and was first mentioned by Hippocrates (circa 450 B.C.), who advised his troops to pack wounded soldiers in the snow. In modern medicine, the primary goal of TTM was to reduce and support a patient’s body temperature (between 32°C and 36°C) for 24-48 hours post cardiac arrest. The temperature range and duration of cooling varied depending on the patient’s condition and the prevailing clinical guidelines.

Implementing TTM included conventional cooling techniques, surface cooling systems, and intravascular cooling systems through a central venous catheter. The landmark 2002 Hypothermia After Cardiac Arrest (HACA) study found that unconscious adult patients with spontaneous circulation after out-of-hospital cardiac arrest because of ventricular fibrillation had better long-term survival and neurological outcomes when cooled to 32-34°C for 24 hours compared to those receiving standard care at normothermia.

A 2013 Targeted Temperature Management (TTM) trial compared two different temperature targets (33°C versus 36°C) in unconscious survivors of out-of-hospital cardiac arrest and found no significant variance between the two groups in terms of survival or neurological outcomes. This study suggested fever prevention as a primary benefit rather than the specifics of target temperature.

The Goal of Targeting Temperature Management

The goal of TTM was to decrease cellular metabolism and oxygen demand physiological stress that compromised oxygen supply. The reduction in oxygen demand can decrease ischemic and reperfusion injury in the brain and other organs and offer neuroprotective effects by reducing harmful substances produced during stress, minimizing inflammation, and decreasing intracranial pressure.

After resuscitation, the body undergoes reperfusion, leading to a cascade of metabolic and cellular events that can cause significant physiologic harm. Gradual rewarming prevents complications, including rebound hyperthermia and further brain injury.

Reperfusion injuries refer to tissue damage caused when blood supply returns to the tissue after a period of ischemia. TTM may have applications in other clinical scenarios, including traumatic brain injury, stroke, and neonatal hypoxic-ischemic encephalopathy. In neonates with hypoxic-ischemic encephalopathy, several studies have shown improved survival and neurological outcomes with TTM.

The 2014 HYPERION (Targeted Temperature Management for Cardiac Arrest with non-shockable rhythm) study showed that in patients with coma, moderate hypothermia improved neurological outcomes at 90 days compared with targeted normothermia.

Overall research suggests that outcomes and health-related quality of life did not improve from hypothermia and in patients suffering out-of-hospital cardiac arrest, induced hypothermia did not lead to lower mortality.

The TTM2 trial, published in 2021 modified the guidelines of the first TTM study (2002) and harmonized that temperature management to normothermia might be necessary for improved patient outcomes.

What Nurses Need to Know About Targeting Temperature Management

Today TTM still exists, and intensive care nurses (ICU) are at the forefront of administering direct patient care, managing potential complications, and ensuring optimal patient outcomes through the coordination of the healthcare team.

The ICU nurse’s role includes initiating TTM through a cooling device, patient monitoring, and observing the patient’s vital signs. Nurses should also note the patient’s neurologic status and potential side effects, including shivering, which can increase oxygen demand. Physiological changes such as coagulopathy, cardiac arrhythmias, and impaired immune response can increase the risk of infections.

The following list contains additional responsibilities a nurse should take on when caring for a patient undergoing targeting temperature management:

• Manage the rewarming protocol (0.25°C to 0.5°C per hour) to prevent rebound hyperthermia.
• Electrolyte Management: Hypothermia can lead to electrolyte imbalances.
• Offer the patient comfort and support, such as managing sedation and analgesics or providing skin care.
• Communicate with the patient’s family (explaining TTM, its benefits, and potential risks).

The Bottom Line

TTM is not without risk. Beyond the intensive care resources consumed during cooling, potential complications include the risk of infection, coagulopathy, suppression of the immune system, and electrolyte imbalances.

Though research supports TTM in response to specific circumstances, ongoing studies continue to refine its application within the optimal patient populations, timing, duration, and effective target temperatures. In the hospital setting, TTM should be part of a comprehensive post-resuscitation care bundle, which includes hemodynamic optimization, seizure management, and glucose control.

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