The protocol for Cold Injuries:Cold Injury
Let’s break it down!
Cold weather injuries remain a constant threat to soldiers operating in austere environments. In 2018-2019, the military had the highest recorded number of cold-weather injuries among the past 5 seasons, with frostbite accounting for most injuries. The crude overall incidence rate of cold injury for all active component service members in 2018–2019 was 36.5 per 100,000 people. Due to the adverse impact on operations and the high financial costs of treatment and disability, it’s important that we understand how to prevent and treat these injuries.
Cold injuries are divided into three main categories:
- Non-freezing injuries
- Freezing injuries
Non-Freezing Cold Injuries
These are generally the milder forms of cold-weather injuries caused by extended exposure to temperatures less than 15°C (59°F) without tissue freezing. This can be further subdivided into the following:
- Frostnip: Mildest form affecting the nose, hands, ears, and feet. Frostnip is a form of self-limited cold-induced paresthesia that reverses upon rewarming.
- Chilblains: Inflamed skin and soft tissue lesions. Chilblain is a chronic process caused by damage to capillaries
- Trench Foot: Caused by damp cold conditions; leads to nerve, vascular, and soft tissue injuries. If not treated, can lead to gangrene and necessitate amputation
Freezing Cold Injuries
Involves the actual freezing of the affected body part. The severity is determined by which layers of tissue are affected, much like burn injuries. It’s broken down into the following degrees:
- 1st degree: epidermis
- 2nd degree: dermis
- 3rd degree: subcutaneous tissue
- 4th degree: deeper tissues
Refers to a systemic lowering of the body’s core temperature, further broken down by severity into the following classes:
- Severe Hypothermia (HT-III or IV): Temperature less than 28°C (82°F):
- Associated with hemodynamic instability or cardiac arrest, coma mimicking brain death.
- Treated with ECLS. Alternatively, use invasive rewarming.
- Moderate Hypothermia (HT-II): Temperature between 28-32°C (82-89°F):
- Associated with dysrhythmias, change in mental status.
- Use active external rewarming.
- Mild Hypothermia (HT-I): Temperature between 32-35°C (89-95°F):
- Associated with shivering, cold diuresis, amnesia, ataxia.
- Remove from cold and use passive rewarming.
Non-Freezing Cold Injury
Symptoms of these injuries are typically mild; frostnip will cause a sort of burning, itching, numbing sensation that frequently goes away after rewarming. No permanent damage is done. Chilblains are slightly worse in that they cause more of a blistering effect from an abnormal vascular response to long-periods of cold weather, often not appearing until after the area is rewarmed.
Trench foot is unique in that it has less to do with cold temperatures and more to do with continuous exposure to moisture. It presents with pain and burning sensations, but also with hyper hydrated and wrinkled plantar surfaces. This is a classic picture of trench foot:
Freezing Injury (frostbite)
Superficial frostbite can look similar to frostnip or chilblains, but deep frostbite will have a white, waxy look or even a gray, ashy appearance. Patients often describe severe pain at first but then transitions into being painless. The video below shows a case of deep frostbite on the feet:
Hypothermia can begin as profuse shivering and poor coordination, but then quickly transition into neurological deficits that make the patient appear to be in a drunken stupor. When severe hypothermia kicks in, the patient may stop feeling cold, lose consciousness, and develop lethal cardiac arrhythmias. The video below shows how damaging hypothermia can be:
Non-freezing cold injuries don’t require excessive measures. The patient should be removed from the environment (if ambulatory) and gradually rewarmed. Rubbing may cause further tissue damage and rapid rewarming may increase pain and edema and is thought to increase the metabolic demands of injured skin.
Keeping the patient’s hands and feet dry by replacing wet clothing is essential. Also, the patient will likely be in substantial pain so NSAIDs are warranted. No narcotics should be needed.
Severe chilblains or trench foot roughly warrants the same treatment, although further wound care may be necessary.
Most of this is fairly obvious, but I’ll hit on a few of the main points:
If thawed, refreezing will most likely result in amputation
It’s well documented that refreezing a limb with frostbite is actually worse in terms of cellular damage and tissue inflammation than just keeping the limb frozen. That’s why if the patient is unable to be removed from the environment or refreezing is likely to occur for whatever reason, the only action you should take is to protect the tissue from further injury via dry Kerlix and separating the digits with a dressing to prevent them becoming stuck together.
Once thawing has occurred, expect intense pain requiring narcotic use
Many patients will often go on for long periods of time with frostbite due to the painless nature of it. However, the rewarming process is remarkably painful, which may require Morphine or Fentanyl from the Pain Management protocol.
Warm water immersion
Regardless of whether or not the frostbite is superficial or deep, warm water immersion (at a temperature of 98.6 to 102.2°F) is the most ideal. This process will take approximately 30 minutes, but it should be done until the tissue has thawed out and become soft. Dry heat from hand warmers, MRE heaters, and other devices are difficult to regulate so they should be avoided if possible
The ultimate treatment goal for hypothermia is to rewarm the patient until you have achieved a normal core temperature, which generally involves removing them from the environment, keeping them dry, and providing passive/active rewarming. However, there are a few extra points to remember:
If moderate/severe, do not feed or exercise the patient
Those in moderate/severe hypothermia will likely have an altered mental status, so feeding them may increase the risk of aspiration. Exercising the patient may be beneficial for mildly hypothermic patients by generating heat through motor movements, but for severely hypothermic patients it may actually be harmful because muscle perfusion will only divert warm blood away from the patient’s core.
If IV fluids are indicated, administer glucose-containing IV fluids warmed at 101.6 degrees or 1 amp of D50.
Hypothermia patients are frequently dehydrated so IV fluids are often indicated. In addition, patients who prove to be very difficult to rewarm may actually be suffering from hypoglycemia, which can cause profound hypothermia. You can knock out two birds with one stone by administering a dextrose solution such as D5W, D10, or an amp of D50. For fluid warming strategies, see Fluid Warmer
If unconscious, avoid sudden movements…
The worst cases of hypothermia tend to cause funky things to happen to the heart. They can become profoundly bradycardic (HR < 60) and are often confused for being in cardiac arrest due to the inability to detect a strong pulse. These patients are extremely sensitive to sudden movements, which may cause ventricular fibrillation. While loading these patients, you should always be prepared to provide cardiac or ventilatory support.
Most cases of non-freezing cold injuries can be managed conservatively, but those that cause the patient to become non-ambulatory (ex. trench foot or severe chilblains) will obviously require evacuation from the environment. Priority evacuation for frostbite is necessary as they will potentially need excessive wound care and treatment for potential infections. Hypothermia patients may require additional rewarming tools, as seen in the videos above. They are also at a significant risk of cardiac issues, which will be near impossible for the average line medic to fix without ACLS capabilities. Thus, Urgent evacuation is highly warranted.
Good luck out there!
- EMRAP Corependium: Frostbite and Nonfreezing cold injury
- Health.mil: Frostbite
- UpToDate: Nonfreezing cold water (trench foot) and warm water immersion injuries
- UpToDate: Frostbite Emergencies
- Advanced Tactical Paramedic Protocols Handbook. 10th ed., Breakaway Media LLC, 2016.