Surface cooling is typically the fastest way to begin cooling, though it can be the most difficult to regulate. The most basic way to cool a patient is to use numerous ice packs applied to the head, neck, torso, and limbs. This method is cheap, uses materials quickly available in most emergency departments, and is intuitive to most staff. However, accurate temperature regulation can be difficult when using ice packs alone. Several commercially available tools, such as cooling blankets and gel pads, can be used to achieve surface cooling.

Cooling blankets will typically cover much of the patient’s body; water circulates through the blanket for conductive temperature regulation. The major advantages of cooling blanket systems are their low cost and quickness of application. One drawback of these systems is they reduce access to the patient for nursing care and for procedures like cardiopulmonary resuscitation and defibrillation. Further, there is a risk of thermal injury from inadvertent punctures of the blanket.

Gel pad systems cover less of the body and provide easier access to the patient for procedures and nursing care. Gel pads can be more effective than blankets in achieving and maintaining temperatures in the desired range because they are applied directly to the body. However, gel pads can be more time consuming to apply than blankets, especially on obese patients. Some gel pad systems reduce the risk of thermal injury from pad punctures by using negative pressure to pull water through the pads. Initial and recurrent costs tend to be much higher for gel pad systems than for blankets.

Surface cooling systems in general have the advantage of being noninvasive and quickly applicable to the patient. They have the disadvantage of requiring a separate mechanism of core-temperature monitoring, such as a Foley or nasogastric tube equipped with a thermometer or repeated rectal temperatures. In addition, speed of cooling and ability to maintain temperature within the desired range can vary widely for the different systems.

Core cooling techniques employ more invasive methods to reach and maintain hypothermia. Thermometer-equipped nasogastric tubes can be used to infuse cooled oral fluids and monitor esophageal temperature, though the risk of aspiration makes this less desirable. Cooled intravenous fluids can be infused by peripheral lines or standard central lines, though a separate temperature monitoring mechanism is needed.

Some commercially available intravenous cooling catheters (either made of metal or containing balloons filled with cold saline) also have built-in thermometers for temperature monitoring. The advantage of these systems is that because nearly all patients requiring cooling also will require a central line and invasive temperature monitoring, these needs can be met with a single catheter, and there is no external barrier impeding physical access to the patient for other procedures. The main drawbacks of intravenous cooling catheter systems are high cost and invasiveness.