Frostnip, Frostbite, and Mild Hypothermia

Presentation

Frostnip occurs when skin surfaces, such as the tip of the nose and ears, are exposed to an environment cold enough to freeze the epidermis. These prominent exposed surfaces become blanched and develop paresthesia and numbness but remain pliable. As they are rewarmed, they become hyperemic and are usually very painful. Pernio (chilblains) is an inflammatory skin injury caused by exposure to cold (often repeatedly) above the freezing point and may be idiopathic or secondary to connective tissue disease or cryoglobulinemia.

Superficial frostbite can be either a partial-thickness or a full-thickness freezing of the dermis. The frozen surfaces appear white or mottled, feel doughy or hard, and are insensitive. With rewarming, these areas become erythematous and edematous, with severe pain ( Fig. 171.1 ). Blistering occurs within 24 to 48 hours with deeper partial-thickness frostbite.

Patients who have core body temperatures between 32 and 35 °C are considered to suffer from mild hypothermia and may demonstrate tachypnea, tachycardia, dysarthria, and shivering.