Cold injuries
Cold injuries: Excerpt from Handbook of Diseases
Overexposure to cold air or water causes cold injuries. They occur in two major forms: localized injuries (such as frostbite) and systemic injuries (such as hypothermia). Untreated or improperly treated frostbite can lead to gangrene and may necessitate amputation; severe hypothermia can be fatal.
The risk of serious cold injuries, especially hypothermia, is increased by youth, lack of insulating body fat, wet or inadequate clothing, old age, drug abuse, cardiac disease, smoking, fatigue, hunger and depletion of caloric reserves, and excessive alcohol intake (which draws blood into the capillaries and away from body organs).
Causes
The specific causes of frostbite and hypothermia vary.
Frostbite
Localized cold injuries occur when ice crystals form in the tissues and expand extracellular spaces. With compression of the tissue cell, the cell membrane ruptures, interrupting enzymatic and metabolic activities. Increased capillary permeability accompanies the release of histamine, resulting in aggregation of red blood cells and microvascular occlusion. Frostbite results from prolonged exposure to dry temperatures far below freezing.
Hypothermia
Chemical changes result from hypothermia that slow the functions of most major organ systems, such as decreased renal blood flow and decreased glomerular filtration. Hypothermia results from cold-water near-drowning and prolonged exposure to cold temperatures.
Signs and symptoms
Both frostbite and hypothermia produce distinctive signs and symptoms.
Frostbite
Two types of frostbite can occur: superficial or deep. Superficial frostbite affects skin and subcutaneous tissue, especially of the face, ears, extremities, and other exposed body areas. Although it may go unnoticed at first, upon returning to a warm place, frostbite produces burning, tingling, numbness, swelling, and a mottled, blue-gray skin color.
Deep frostbite extends beyond subcutaneous tissue and usually affects the hands or feet. The skin becomes white until it’s thawed; then it turns purplish blue. Deep frostbite also produces pain, skin blisters, tissue necrosis, and gangrene.
Hypothermia
Indications of hypothermia (a core body temperature below 95° F [35 C]) vary with severity.
❑ Mild hypothermia produces a temperature of 89.6° to 95° F (32° to 35° C), severe shivering, slurred speech, and amnesia.
❑ Moderate hypothermia results in a temperature of 86° to 89.6° F (30° to 32° C), unresponsiveness or confusion, muscle rigidity, peripheral cyanosis and, with improper rewarming, signs of shock.
❑ Severe hypothermia produces a core temperature of 77° to 86° F (25° to 30° C), with loss of deep tendon reflexes and ventricular fibrillation. The patient may appear dead, with no palpable pulse or audible heart sounds. His pupils may dilate, and he’ll appear to be in a state of rigor mortis. A temperature drop below 77° F (25° C) causes cardiopulmonary arrest and death.
Diagnosis
A history of severe and prolonged exposure to cold may make this diagnosis obvious. Nevertheless, hypothermia can be overlooked if outdoor temperatures are above freezing or if the patient is comatose.
Treatment
With a localized cold injury, treatment consists of rewarming the injured part, supportive measures and, in severe cases, a fasciotomy to increase circulation by lowering edematous tissue pressure. However, if gangrene occurs, amputation may be necessary.
With hypothermia, therapy consists of immediate resuscitative measures, careful monitoring, and gradual rewarming of the body.
Frostbite
❑ Remove constrictive clothing and jewelry. Slowly rewarm the affected part in tepid water (about 100° to 108° F [37.8° to 42.2° C]). Give the patient warm fluids to drink.
❑ When the affected part begins to rewarm, the patient will feel pain, so administer an analgesic. Check for a pulse. If the injury is on the foot, place cotton or gauze sponges between the toes to prevent maceration. Instruct the patient not to walk.
Clinical tip When treating a patient with frostbite, never rub the injured area. This aggravates tissue damage. Also, be careful not to rupture any blebs.
❑ If the injury has caused an open skin wound, give an antibiotic and tetanus prophylaxis.
❑ Early surgical intervention isn’t indicated unless wet gangrene or severe infection of the eschar develops.
Clinical tip Prevent refreezing of thawed tissues because significant tissue damage may occur. Also, it’s impossible to assess the depth of frostbite injury in the early stages.
Hypothermia
❑ If the patient has no pulse or respirations, begin cardiopulmonary resuscitation (CPR) immediately and, if necessary, continue it for 2 to 3 hours. (Remember: Hypothermia helps protect the brain from anoxia, which normally accompanies prolonged cardiopulmonary arrest. Therefore, even after the patient has been unresponsive for a long time, resuscitation may be possible, especially after cold-water near-drownings.) Perform CPR until the patient is adequately rewarmed.
❑ Move the patient to a warm area, remove wet clothing, and keep him dry. If he’s conscious, give warm fluids with high sugar content, such as tea with sugar. If the patient’s core temperature is above 89.6° F (32° C), use external warming techniques. Bathe him in water that’s 104° F (40° C), cover him with a heating blanket set at 97.9° to 99.9° F (36.6° to 37.7° C), and cautiously apply hot water bottles at 104° F (40° C) to groin and axillae, guarding against burns.
❑ If the patient’s core temperature is below 89.6° F (32° C), use internal and external warming methods. Rewarm his body core and surface 1° to 2° F (0.5° to 1.1° C) per hour concurrently. (If you rewarm the surface first, rewarming shock could cause potentially fatal ventricular fibrillation.)
❑ To warm inhalations, provide oxygen heated to 107.6° to 114.8° F (42° to 46° C). Infuse I.V. solutions that have been warmed to 98.6° F (37° C), and perform nasogastric lavage with normal saline solution that has been warmed to the same temperature.
❑ The patient may need peritoneal lavage, using normal saline solution (full or half strength) warmed to 104° to 113° F (40° to 45° C). If the patient has severe hypothermia, he may need heart and lung bypass at controlled temperatures and thoracotomy with a direct cardiac warm-saline bath. Avoid using central venous catheters in patients with severe hypothermia to prevent arrhythmias.
Clinical tip Consider administering antibodies if sepsis is the suspected cause of the hypothermia. Consider giving a steroid only if adrenal suppression or insufficiency is suspected to be the precipitating cause of the hypothermia.
Special considerations
❑ Before discharging a patient with frostbite, tell him about possible long-term effects: increased sensitivity to cold, burning and tingling, and increased sweating. Warn against smoking; this causes vasoconstriction and slows healing.
❑ During treatment for hypothermia, monitor arterial blood gas values, intake and output, central venous pressure, temperature, and cardiac and neurologic status every half hour. Monitor laboratory results, such as complete blood count, blood urea nitrogen and electrolyte levels, and prothrombin and partial thromboplastin times.
age alert If the patient is a child, suspect neglect or abuse; make sure a thorough patient history is performed.
❑ If the patient developed a cold injury because of inadequate clothing or housing, refer him to a community social service agency.
❑ To help prevent future cold injuries, tell the patient to wear mittens (not gloves); windproof, water-resistant, many-layered clothing; two pairs of socks (cotton next to the skin, then wool); and a scarf and a hat that cover the ears (to avoid substantial heat loss through the head).
❑ Advise the patient not to drink alcohol or smoke and to get adequate food and rest before prolonged exposure to cold.
❑ Caution the patient to find shelter early or increase physical activity if caught in a severe snowstorm.
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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