Cooling Techniques for Hyperthermia

Indications

Indications for cooling include any signs of heat-related illness in the presence of an elevated body temperature. Historically, heat-related illness has been defined as a core temperature exceeding 40 °C. However, any temperature above normal in a symptomatic patient without another identifiable cause warrants consideration of cooling interventions. The immediate objective is to reduce core temperature below 39 °C, with the ultimate goal of achieving the normal range of 36 °C to 38 °C. Assessment for severe heat stroke should include evaluation of hemodynamic stability to guide the urgency and intensity of rapid cooling.[7]

Contraindications

The only absolute contraindication to cooling is a normal or low body temperature. Hyperthermia may reflect sepsis, toxic ingestion, withdrawal, or another underlying etiology, and disease-specific treatment should not be overlooked. Clinicians should prioritize standard resuscitation measures, emergent management of airway, breathing, and circulation, and medical management guided by a broad differential diagnosis.

Equipment

Several cooling methods are available in the emergency department using standard equipment, including the following:

• Cooling blankets
• Cold intravenous saline
• Ice packs
• Cool water immersion or bath
• Foley catheter irrigation
• Sheets or towels
• Waterproof body bags

Additional equipment that may facilitate cooling includes a spray bottle and a fan.

Personnel

A single provider can perform all cooling techniques described in this activity. However, additional personnel facilitate more rapid cooling by enabling parallel interventions.

For example, the physician should assess the patient for the spectrum of heat-related illness, determine the need for external cooling, and evaluate for coexisting injuries or comorbidities. Departmental technicians can prepare and set up equipment, including temperature monitoring devices, vital sign monitors, ice, body bags, and other required supplies. Nursing staff can assist with patient positioning and continuous monitoring of vital signs, with particular attention to core temperature. Environmental or nutrition support personnel can facilitate the timely delivery of ice and other necessary supplies on a patient-by-patient basis.

Preparation

During preparation, the patient should be fully exposed, and intravenous access should be established. The team should assess for external signs of trauma. Continuous cardiac monitoring is recommended when available. Core body temperature should be closely monitored using an intracavitary thermometer, with esophageal, rectal, or bladder probes commonly employed.

Technique or Treatment

The cold-water immersion method cools the patient at an approximate rate of 0.13 °C per minute. The procedure begins by placing the patient in a waterproof body bag. Ice is added first, followed by water to create an ice slurry. The bag may then be secured up to the patient’s chest. The lower extremities may be submerged initially if the bag is too small to accommodate the entire body, with extremities exposed as needed to allow other medical interventions. The bag may be drained by cutting the inferior portion once the patient’s core temperature reaches the target of 39 °C, and the patient is positioned in reverse Trendelenburg.

Evaporative cooling reduces core temperature at an approximate rate of 0.05 °C per minute and involves continuous application of cold water to the skin using sponging or a spray bottle. A fan should be directed at the patient while spraying or sponging to enhance evaporation and accelerate cooling. Alternatively, a sheet may be submerged in ice water, wrung out, and wrapped around the patient. The sheet should be replaced and resubmerged when it loses its cooling effect.

Ice packs may also be applied to the groin, axillae, neck, and torso, which are most effective in lowering core temperature. Cold saline may be infused with caution to monitor for induced shivering. A Foley catheter may be used for bladder irrigation with cold saline. Frequent replacement of ice packs and repeated application of cold water facilitate more rapid cooling.[8][9]

These methods require continuous reapplication of water and ice to maintain efficacy (see Image. Cooling Techniques for Hyperthermia). Monitoring of core temperature is essential to guide ongoing reapplication and prevent overcooling.

Complications

Cooling is a critical intervention for heat-related illness and is associated with few complications. Vital signs must be monitored closely throughout the cooling process. Core body temperature and the presence of shivering should be continuously assessed, as shivering can impede effective cooling. Critically ill patients may further decompensate during intervention. Core temperatures below normal (36 °C) put patients at risk for hypothermia-related complications, including arrhythmias and coagulopathy. Skin integrity should also be monitored, as prolonged exposure to ice can cause tissue damage. Covering ice packs with a towel or sheet and regularly repositioning them mitigates this risk.[10][11][12][13]

Clinical Significance

Rapid reduction of core body temperature is the most critical intervention in managing heat-related illness and heat stroke. Cooling may also serve as an adjunct to standard therapies for conditions that cause secondary hyperthermia. The techniques described are straightforward, effective, and easily implemented in the emergency department. These approaches require minimal training and may be performed by a single provider. The methods are applicable across a variety of clinical environments. Timely identification of patients who will benefit from cooling is essential for effective management.[14]

Enhancing Healthcare Team Outcomes

Hyperthermia can present frequently in certain regions to the emergency department. Some patients may require systemic cooling to prevent neurological injury. Rapid reduction of core body temperature remains the most critical intervention in managing heat-related illness and heat stroke. Optimal cooling is achieved through an interprofessional approach involving neurologists, internists, emergency physicians, and critical care nurses.

Cooling may also serve as an adjunct to standard therapies for conditions causing secondary hyperthermia. Timely identification of patients who will benefit from cooling interventions is essential for effective management.