Cooling Techniques for Hyperthermia

Indications

Indications for cooling include any signs of heat-related illness in an elevated body temperature. Previously, heat-related illness has been defined as a core body temperature greater than 40 C. However, any elevation above normal body temperature in a symptomatic patient is an indication to consider cooling. The objective is to rapidly decrease the temperature below 40 C, with the final goal of reaching a normal range (36 C to 38 C). It is important to note if the patient's other vital signs, like hemodynamic instability, indicate severe heat stroke, in which case, rapid cooling is the most crucial intervention to stabilize the patient.[2]

Contraindications

The only absolute contraindication to cooling is a normal or low body temperature. Hyperthermia in a patient may be a sign of sepsis, toxic ingestion, withdrawal, or another etiology, in which case disease-specific treatment should not be overlooked. Care should be taken to prioritize usual resuscitation and emergent management of airway, breathing, and circulation.

Equipment

There are several cooling methods available in the emergency department with standard equipment, such as:

• Cooling blanket
• Cold saline
• Ice packs
• Cool water bath
• Foley catheter
• Sheets/towels.

Additional equipment that may be useful includes a spray bottle and a fan.

Personnel

A single provider can perform all of the cooling techniques described in this article. However, additional personnel will allow for faster cooling utilizing parallel interventions.

Preparation

In preparation, the patient should be exposed completely, and intravenous access established. When available, placing the patient on a cardiac monitor is recommended. Additionally, an intra-cavitary thermometer may be placed to monitor core body temperature closely. Commonly, esophageal, rectal, and bladder probes are used.

Technique or Treatment

Continuous application of cold water to the skin can be achieved by either sponging the patient or using a spray bottle. Placing a fan to blow directly on the patient while also spraying or sponging will increase the rate of evaporation and, thereby, will more rapidly decrease body temperature. Another option is to submerge a sheet in cold water, wring it out, and then wrap the patient in the damp sheet. This can be changed and re-submerged when it is no longer cool. The downside of these methods is that they require continuous reapplication of the water and ice to maintain efficacy (see Graphic. Cooling Techniques for Hyperthermia).

Another option is to apply ice packs to the patient. The areas most effective in cooling core temperature are the groin, axillae, neck, and torso. Cold saline can be infused with care to monitor for resultant shivering. If the patient has a Foley catheter, it can also irrigate the bladder with cold saline. More frequent ice pack changes and reapplication of cold water will allow for more rapid cooling.[3][4]

One of the most effective cooling methods is a water bath with water at 90 F (26.7 C). Colder temperatures may cause shivering.

Complications

Overall, cooling is a useful intervention that has few complications. The patient's vital signs must be monitored closely during the cooling process. As mentioned, patients should be monitored for shivering and hindering cooling efforts. Critically ill patients may further decompensate during cooling. Additionally, if a patient's body temperature drops below normal (36 C), they will be at risk for the sequelae of hypothermia, including arrhythmias and coagulopathy. An important organ to monitor during the cooling process is the skin. It is susceptible to damage from prolonged exposure to ice. Covering ice packs with a towel or sheet and regularly adjusting the application site will mitigate this risk.[5][6][7][8]

Clinical Significance

Decreasing core body temperature is the most critical intervention in managing heat-related illness and heat stroke. Cooling may also be an adjunct to the usual therapies for numerous conditions that may cause secondary hyperthermia. The techniques described are easy, simple, and effective ways of cooling a patient in the emergency department. They require little training and can be performed by an individual provider. Additionally, they are applicable in many environments. Rapidly identifying patients benefitting from this intervention is the key to effective management.[9][10]

Enhancing Healthcare Team Outcomes

Hyperthermia is not an uncommon presentation to the emergency room. Some of these patients may require systemic cooling to prevent neurological damage. Decreasing core body temperature is the most critical intervention in managing heat-related illness and heat stroke. The cooling is best done with an interprofessional team that includes a neurologist, internist, emergency department physician, and ICU nurses

Cooling may also be an adjunct to the usual therapies for numerous conditions that may cause secondary hyperthermia. Rapidly identifying patients benefitting from this intervention is the key to effective management.[9][10]

The outcomes in most patients who are promptly treated are good.