Understanding Freezing Injuries

The cold weather has certainly arrived and with it comes an increased risk of cold-related injury. While it is important to keep in mind that cold-related injury can occur in just about any month of the year depending on the conditions, January - March is the most critical time to be vigilant. In the spirit of a healthy and safe winter season, let us review two common conditions: “frostbite” and the less familiar “frostnip”.

What is frostnip and how does it differ from frostbite?

Frostnip is a mild cold-induced condition consisting of pallor of the affected area with associated tingling or mild pain. The key with frostnip is that it is quickly reversible with rewarming.

Frostbite, on the other hand, is the result of tissue injury due to freezing and rewarming. In addition to direct injury to the tissue cells, small blood vessels feeding the tissues are likely damaged causing resultant inflammation, blood clotting, and subsequent poor blood supply to the tissues.

Frostbite most commonly affects the head, hands, and feet. It can occur extremely quickly (within seconds to minutes) when touching icy metal surfaces or in high wind or high altitude conditions.

The degree of frostbite can be difficult to determine by visual inspection at the outset of the injury event and can range anywhere from superficial skin involvement to deep injury to muscle and bone. Early signs of frostbite may be challenging to identify in darker skin tones. Patients typically report cold, numbness, and clumsiness of the affected area. The skin is typically discolored and may be hard or waxy to the touch. Blistering may be evident if the area has begun thawing.

What are the risk factors for frostnip and frostbite?

Risk factors include activities or occupations with increased cold exposure including military, outdoor winter athletics, the elderly, the homeless, and those who abuse drugs and alcohol. Exhaustion, dehydration, and malnutrition may result in decreased ability to respond to cold conditions.

What can you do to prevent cold weather injury?

Adequate layered clothing for the conditions is key. A good base layer should have properties to wick moisture away from the body. Avoid layering too tightly; layers should be somewhat loose to allow air to warm between the layers.  The top layer should be impervious to wind. Be sure your face is also covered. Excessive sweating of the hands and feet can lead to frostbite so gloves and socks should also have moisture-wicking capabilities.

What is the treatment for frostbite?

If you believe you have suffered frostbite you must seek emergency medical attention right away. In the interim, be sure to remove wet and constrictive clothing and protect the affected area against wind. Do not rub the area as it can cause further injury. If possible, immobilize and elevate the area. 

Use caution when considering rewarming before presentation to the hospital. Do not warm the affected area if you believe that it may be subject to refreezing as that will likely cause severe damage. Rewarming can be quite painful. If you do choose to begin the process of reheating while en route to the hospital, gently immerse the affected area in warm, body-temperature water. Do NOT use hot water and do not use dry heat.