EMS Methods to Cool a Patient in the Field

Indications

Indications for cooling include any signs of heat-related illness in the presence of elevated body temperature. Previously, heat-related illness has been defined as core body temperature greater than 40 degrees 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 degrees C, with the final goal of reaching the normal range (36 degrees C to 38 degrees C). It is important to note the patient's other vital signs, as hemodynamic instability indicates 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 normal or low body temperature. Hyperthermia in a patient may be a sign of sepsis, toxic ingestion, or withdrawal, or another etiology, in which case disease-specific treatment should not be overlooked. Care should be taken to prioritize the usual resuscitation and emergent management of airway, breathing, and circulation.

Equipment

Several cooling methods utilize standard equipment, such as:

• Cold saline
• Ice packs
• Sheets/towels

Additional equipment that may be useful includes:

• Cooling blankets
• Spray bottle
• Fan
• A pool, such as an inflatable children's pool

Personnel

All of the cooling techniques described in this article can be performed by a single provider. However, additional personnel will allow for faster cooling utilizing parallel interventions.

Preparation

Make sure to take the patient's vital signs and ensure no immediate airway compromise prior to cooling. The patient should be completely exposed, and intravenous (IV) access obtained.

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 the patient, will increase the rate of evaporation, and thereby more rapidly decrease body temperature. Another option is to submerge a sheet in cold water and then wring it out and wrap the patient in the damp sheet. This sheet 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. [2]

Another option is to apply ice packs to the patient. The areas that are 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. More frequent ice pack changes and reapplication of cold water will allow for more rapid cooling.[3]

If a pool is available, then ice water immersion should be performed. Fill the pool with water and ice. Place the patient in the pool, taking care to submerge the torso to the groin and axillae preferentially to the extremities. Frequently recheck the patient's vital signs and monitor mental status. When the temperature is below 40 degrees C, removed the patient from the pool.[4]

Complications

Overall, cooling is a benign 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, which will hinder cooling efforts. Critically ill patients may further decompensate during cooling. Additionally, if a patient's body temperature drops below normal (36 degrees C), they will be at risk for the sequelae of hypothermia. 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 site of application will mitigate this risk.[5]

If the patient was submerged in ice water, make sure to continue to monitor for hypothermia, and wrap the patient in blankets so as not to leave them exposed.[6][7][8]

Clinical Significance

In managing heat-related illness and heat stroke, decreasing core body temperature is the most critical intervention. The techniques described are easy, simple, and effective ways of cooling a patient in the field. They require little training and can be performed by an individual provider. Additionally, they are applicable in many environments. Rapidly identifying patients who would benefit from this intervention is the key to effective management.

Enhancing Healthcare Team Outcomes

EMS will frequently encounter patients with hyperthermia. While cooling the patient can take place via various methods, it is vital to transport the patient to the ED ASAP. The management of hyperthermia is best done under controlled settings by an interprofessional team approach, including nurse practitioner, emergency department physician, internist, and specialty-trained nursing staff, all working collaboratively to achieve optimal patient outcomes. [Level V] If there is a delay in transport, hyperthermia can induce seizures that tend to affect outcomes adversely.