Frostbite: Difference between revisions
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===Blisters and dressings=== | ===Blisters and dressings=== | ||
*Blisters containing clear or milky fluid should be debrided and covered in aloe vera, a potent anti-prostaglandin agent, every 6 h. | |||
*Splinting, elevating, and wrapping the affected part in a loose, protective dressing should follow the administration of the aloe vera cream. | |||
*Padding should be put between the patient’s toes if affected. | |||
*Haemorrhagic blisters should be left intact to prevent desiccation of the underlying tissue. If they restrict movement they can be drained with their roofs left on. | |||
===Antibiotics=== | ===Antibiotics=== | ||
===Tetanus toxoid=== | ===Tetanus toxoid=== |
Revision as of 19:49, 4 September 2020
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Jaspinder Kaur, MBBS[2]
Synonyms and keywords:
Overview
Frostbite (congelatio in medical terminology) is a freezing, cold thermal injury, which occurs on being exposed to temperatures below their freezing point (typically −0.55°C, but can occur as high as 2°C) for a sustained period of time. It is a condition that has far-reaching consequences in terms of functional morbidity to a population that are often young, fit and healthy prior to sustaining thermal injury. Currently, the presentation of frostbite is increasing within the civilian population, particularly among those who partake in winter sports such as skiing, hiking, mountain and ice climbing. The outdoors is more accessible, and individuals with limited experience/inadequate preparation and protection are highly susceptible to it. Vagrancy, homelessness, industrial injury and malfunctioning or misuse of equipment using NO or CO2 have also been held responsible. Cutaneous circulation plays an important role in thermoregulation by varying blood flow through peripheral structures in order to maintain core body temperature, which is essential for survival. In a cold environment, maximal vasoconstriction in hands and feet is reached when their temperature drops to 15° C. This is followed by local protective cycles of vasodilation if cooling persist, but leads to progressive local ischemia if exposure continues. However, thawing restores blood flow and induces congestion, inflammation and thrombosis in the injured endothelium, which may prompt erythrocyte extravasation due to failure of the vessel wall. According to the depth of the skin damage, necrosis can be so severe that it results in spontaneous or surgical amputation. Frostbite can result in a wide spectrum of injury, ranging from complete resolution without significant sequelae to major limb amputation and its functional consequences. Timely pre-hospital and definitive hospital management are important to minimize final tissue loss and maximize functionality of the affected limb. Once in the hospital setting, the best outcomes will be achieved for the patient when a multidisciplinary approach is utilized. Either intravenous iloprost or thrombolysis with rTPA should be considered in all patients who present within 24 h of sustaining an appropriately severe injury and if the facility is capable of appropriate administration and monitoring. Both treatments should be started as soon as it is practical to gain maximal benefit. Bone scanning is helpful to ascertain deep tissue injury and response to therapy. However, surgeons should not rush to early amputation; if managed correctly in the first few days, significant tissue can be salvaged, which is very important to the final functional outcome. Prevention with education, behaviour modification, following workplace guidelines, and appropriate use of modern equipment in most adventurous tourist destinations is important to reduce frostbite incidence. Once frostbite injury has occurred, little can be done to reverse the changes. Hence, a great preventive care should be taken to avoid its incidence.
Historical Perspective
- 5,000 years ago: An earliest evidence of frostbite was documented among pre-Columbian mummy discovered in the Andes.
- 218 BC: Hannibal lost nearly half his army of 46,000 to frostbite injuries over a two week period of crossing the Southern Alps to reach Italy.
- 1778: Dr. James Thatcher reported that Washington lost 10% of his army to cold-related tissue casualties during the winter times of the Revolutionary War.
- 1812–1813: Baron Dominique Jean Larrey, Surgeon-in-Chief to Napoleon's Army, reported the first systematic medical observations of frostbite during the ill-fated invasion of Moscow during the Fall season, and the subsequent retreat in a harsh Russian winter. He noted the deleterious effects of the freeze–thaw–refreeze cycle by identifing the debilitating effects of daily refreezing that occurred with bonfire thawing and subsequent marching in frigid conditions. He further stated that warming was beneficial; however, not by using the excessive heat of fires. Hence, he concluded the friction massage with snow or ice which results in slow rewarming is an optimal therapeutic standard of care for frostbite in military medicine and practiced for more than 100 years.
- 1930:During World War II, both German and Russian troops moved to a philosophy of rapid rewarming based on work conducted at the Kirov Institute.
- 1941–1942: German troops sustained an estimated 250,000 frostbite injuries in the attempt to take over Moscow; and hence, constitutes the largest reported number of related frostbite injuries in history. Moreover, it was reported that the German army alone performed more than 15,000 amputations for cold related injuries on the Russian front during the winter season.
- 1960: Mills published the first major clinical experience with rapid rewarming and included a concept of total care for frostbite with his report.
Classification
- Frostbite has been divided into 4 tiers or “degrees” of injury, historically following the classification scheme for thermal burn injury. These classifications are based on acute physical findings and advanced imaging after rewarming. These categories can be difficult to assess in the field and before rewarming, since the still-frozen tissue is hard, pale, and anesthetic. An alternate 2-tiered classification which is more appropriate for field use has also been suggested; both of them are elaborated in Table 1.
Level of damage based on two tier | Level of damage based on four tier | Clinical characteristics |
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Superficial damage | First degree | Partial-thickness skin freezing, erythema and hyperemia, mild edema, no blisters or necrosis, occasional skin desquamation and cold sensitivity (5–10 days later). |
Superficial damage | Second degree | Full-thickness skin freezing, erythema, substantial edema, superficial blisters containing clear or milky fluid, desquamation and black eschar formed within two to three weeks. The sequelae include paresthesia, hyperhidrosis, and persistent or transient cold sensitivity. |
Deep damage | Third degree | Skin and subcutaneous tissue freezing, blue or black appearance, substantial edema, hemorrhagic blisters with some necrosis, blue-grey discolouration, deep burning pain on rewarming, thick gangrenous eschar formation, and the sequelae of trophic ulceration and severe cold sensitivity |
Deep damage | Fourth degree | Freezing extending through subcutaneous tissue into muscle, tendon, and bone; deep red and mottled appearance with eventual gangrene; minimal edema; extensive necrosis; eventually dry, black and mummified |
Table 2: Classification scheme for the severity of frostbite injury
Frostbite injuries of the extremity | Grade 1 | Grade 2 | Grade 3 | Grade 4 |
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Extent of initial lesion at day 0 after rewarming | Absence of initial lesion | Initial lesion on distal phalanx | Initial lesion on intermediary (and) proximal phalanx | Initial lesion on carpal/tarsal |
Bone scanning at day 2 | Useless | Hypofixation of radiotracer uptake area | Absence of radiotracer uptake on the digit | Absence of radiotracer uptake area on the carpal/tarsal region |
Blisters at day 2 | Absence of blisters | Clear blisters | Haemorrhagic blisters on the digit | Haemorrhagic blisters over carpal/tarsal region |
Prognosis at day 2 | No amputation; No sequelae | Tissue amputation; Fingernail sequelae | Bone amputation of digit; Functional sequelae | Bone amputation of the limb; +/− systemic involvement; +/− sepsis functional sequelae |
Pathophysiology
- Normal skin blood flow is about 250 ml/min, however; the flow drops to less than 20-50 ml/min during frostbite. As the temperature drops to below 0 degrees Centigrade, blood flow ceases especially in the slower venous system before the arterial system. Depending on the extent of the exposure and subsequent cellular damage proposed to be occurring in the four phases, injuries may be reversible or irreversible. In majority of the cases, recovery from frostbite can take 5-30 days, depending upon the extent of damage.
- Normal physiological response to the cold environment:
- Aim: To conserve the internal body core temperature and the viability of the extremities.
- Peripheral vasoconstriction: It is caused by sympathetic stimulation and catecholamine release which reduces the heat loss.
- Shivering: It is a muscular activity which maintenance or augment the body heat; however, it cannot be sustained for more than a few hours because of the depletion of glycogen, which is the source of heat during shivering.
- Hunting reaction: It protects the extremities by the process of irregular, 5 to 10-minute cycles of alternating vasoconstriction and vasodilation against excessive sustained vasoconstriction with minimal loss of internal body temperature.
- However, this mechanism fails when the body is exposed to cold of a magnitude or a duration that threatens the internal body temperature because the disruption of body core temperature is more deleterious than peripheral vasoconstriction, conservation of core temperature takes precedence over rewarming of the extremities, and the hunting response is replaced by continuous and more intense vasoconstriction that promotes frostbite by means of ice crystal formation, cellular dehydration, and thrombosis of the microvasculature.
- Four pathophysiological phases: Frostbite occurs in four interconnected progressive processes dependent on the rate and duration of freezing, rate of rewarming, and anatomic extent of exposure.
- Prefreeze phase: The tissue cooling leads to local vasoconstriction and ischemia, with the resulting neuronal effects of hyperesthesia and paresthesia.
- Freeze thaw phase: The recognized changes during freezing are (1) extracellular ice formation, (2) intracellular ice formation, (3) cell dehydration and crenation, (4) abnormal electrolyte concentrations due to altered oncotic pressures, and (5) perturbations in lipid–protein complexes. However, the body initially responds to tissue freezing with alternating cycles of vasodilation and vasoconstriction (the “hunting reaction”) which lead to cycles of partial thawing and a prothrombotic microenvironment. With rewarming, ice crystals melt and injured endothelium promotes edema. Epidermal blisters form, and free radical formation continues the insult. Elaboration of inflammatory mediators, prostaglandins, and thromboxanes induces vasoconstriction and causes the vascular stasis period.
- Vascular stasis phase: The persistence of the local vasoconstriction causes hypoxia and acidotic damage to the endothelium, and promotes coagulation and interstitial edema. The vascular endothelium is particularly susceptible. Seventy-two hours after freezing and thawing, the endothelium may be completely obliterated and replaced by fibrin deposition. Investigators also have observed electron microscopic evidence of perivascular fluid extravasation and endothelial swelling and lysis.
- Ischemic phase: Finally, hypoxia, endothelial injury, and local thrombosis lead to the late ischemic phase, in which inflammatory mediators such as prostaglandins, thromboxanes, bradykinins, and histamine trigger additional vasoconstriction, platelet aggregation, and vessel thrombosis. Because these inflammatory mediators peak during rewarming, cycles of refreezing and rewarming can worsen the extent of tissue loss. Therefore, an initial frostbite treatment is targeted at restoring perfusion to the affected limb(s) and limiting tissue loss after rewarming.
Differentiating Frostbite from other Diseases
- Various types of cold injury can mimic each other which are categorized into hypothermia, tissue-freezing injury (frostbite), non–tissue-freezing injury (frostnip, trenchfoot, chilblain, or pernio) in the following Table.
Differential disease | Clinical characteristics |
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Hypothermia |
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Cutaneous burns |
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Cold Urticaria |
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Raynaud phenomenon |
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Frostnip |
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Chilblains (Pernio or Perniosis) |
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Immersion foot (trench foot) |
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Epidemiology and Demographics
- Age: Although the elderly and young children are potentially at high risk from sustaining frostbite injury; however, the published epidemiological studies showed that frostbite is uncommon in these age groups and instead tends to affect adults between the ages of 30–49 years.
- Anatomic location: The feet and the hands account for 90% of injuries reported. Other includes the face (nose, chin, earlobes, cheeks and lips), buttocks/perineum (from sitting on metal seats) and penis (joggers).
- A 12 year study into the inpatient frostbite injuries conducted in Saskatchewan, Canada revealed the incidence of predisposing factors: Alcohol consumption (46%), psychiatric illness (17%), vehicular failure (19%), and drug misuse (4%).
- Alcohol: It causes heat loss through peripheral vasodilatation and deranged judgement which may lead the victim not to seek adequate shelter and further turns to a more severe injury.
Risk Factors
- Various behavioural, physiological and mechanical factors play an important roles in increasing the likelihood of its development and the extent of the damage.
Table: Factors that increase risk for frostbite
Behavioural factors | Physiological factors | Mechanical factors |
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Complications and late sequelae
- Most common: Complex regional pain syndrome and arthritis
- Late or chronic sequelae (70%): Infection, increased cold sensitivity, hyperhydrosis, numbness, skin pigmentation, abnormalities of the nails, joint stiffness, and premature closure of physeal growth plate.
- Frostbite Arthropathy: The acral or exposed areas, including the fingers, toes, nose, and ears, are predominantly affected. Immediately after exposure, the diagnosis of frostbite can be made by the characteristic appearance of swollen, red fingers or toes. Although, the history of cold exposure should be obvious; however, the parents may not have been aware of the increased susceptibility of the very young child to cold injury. Conversely, vasomotor changes suggesting Raynaud's phenomenon may persist for months; and might delay the diagnosis. In the growing child, frostbite produces a characteristic stunting of growth of the small bones and acro-osteolysis. Moreover, secondary symptoms of osteoarthritis may develop in early adulthood.
Prognosis
- Favourable prognostic factors: Retained sensation, normal skin colour, and clear rather than cloudy fluid in the blisters, if present. Early formation of edema and clear blisters that extend to the tips of the digits are a good sign.
- Poor prognostic factors: Non-blanching cyanosis, firm skin, lack of edema, and small, proximal, dark haemorrhagic vesicles indicates damage to the subdermal vascular plexus.
- However, no prognostic features are entirely predictive; and weeks or months may pass before the demarcation between viable and non-viable tissue becomes clear.
- Hence, patients should avoid cold exposure for up to a year after the initial injury.
Diagnosis
Clinical Symptoms
- Severity of symptoms is usually related to the severity of injury.
- Initial presenting complaint: Initially, most patients describe a cold numbness with accompanying sensory loss. The extremity will feel cold to the touch and patients often complain that it feels clumsy, ‘‘like a block of wood’’. Thawing and reperfusion are often accompanied by intense pain.
- At 2-3 days: A throbbing pain begins after rewarming and may persist for weeks or months, even after the tissue becomes demarcated.
- At a week: A residual tingling sensation begins which is probably due to an ischemic neuritis. However, a variation in onset of symptoms exists with some never noticing pain especially among diabetics with previous neuropathic damage.
- In victims without tissue loss, symptoms usually subside within 1 month; whereas with tissue loss, disablement may exceed 6 months.Usually frostbite victims experience some degree of sensory loss for at least 4 years after injury, perhaps indefinitely.
- Aggravating factor: Symptoms gets exacerbated by a warm environment.
- Other sensory deficits: Spontaneous burning and electric current-like sensations.
Clinical Signs
- Frostbite is a clinical diagnosis.
- However, in the initial physical examination, most injuries appear similar, making it difficult to determine the severity until after rewarming.
- The extent of the freezing and tissue loss may not be apparent for 4 to 5 days.
- Frostbite injuries can be classified as either superficial or deep.
- Superficial injuries: It may appear as either a numb central white plaque with surrounding erythema, or as blisters filled with clear or milky fluid with surrounding erythema and edema.
- Deep injuries: It is characterized by either hemorrhagic blisters that develop into a black eschar in 2 weeks or by complete tissue loss and necrosis. Final tissue demarcation may take 3 to 4 weeks to establish. Note the appearance of the skin, sensation to pinprick, and whether the vesicles are clear or hemorrhagic. Identify signs of dehydration, hypothermia, altitude effects (pulmonary edema), and exhaustion.
- Rewarming injuries: During rewarming, edema may start to appear within 3-5 hours and may last 7 days. Blisters tend to appear within 4-24 hours. Presence of eschar will be obvious at 10-15 days and mummification with a line of demarcation may develop in 3-8 weeks.
Diagnostic modality
- The primary role of imaging in frostbite injuries is to help define the precise severity, depth, and extent of tissue injury to better direct nonsurgical and surgical treatment. Imaging also plays an important role in monitoring response to frostbite treatment.
- Table elaborates the different imaging modality used for Frostbite
Diagnostic test | Characteristics |
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Radiographs |
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Digital subtraction angiography (DSA) |
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Multiphase bone scintigraphy |
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SPECT/CT |
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- Other miscellaneous tests: Infrared thermography, laser Doppler studies, digital plethysmography and magnetic resonance imaging/ magnetic resonance angiography.
Treatment
- Treatment of frostbite can be divided into three phases: prethaw field care phase, immediate hospital care phase, and postthaw phase.
Field Treatment
- If a body part is frozen in the field, the frozen tissue should be protected from further damage with the following measures:
- The patient should be moved out of the wind, provided with shelter and be given warm fluids.
- Remove boots (but consider problems of replacement if swelling occurs), and replace wet gloves and socks with dry ones. Warm the cold extremity by placing it in a companion's armpit or groin for 10 min and then replace the boots/gloves. Rubbing the affected part is not recommended because of the potential for worsening direct tissue injury.
- If sensation returns, the patient may mitigate risks (e.g. add a layer and change to warmer or dryer socks or boots) and continue to walk. If there is no return of sensation, the injured should go to the nearest warm shelter (hut or base camp) and seek medical treatment. If at high altitude (>4,000 m), supplementary oxygen should be considered.
- Aspirin 75 mg can be given for its rheologic effect. Ibuprofen 12 mg/kg/day divided into two daily doses (maximum of 2,400 mg/day) should be given for its prostaglandin effect.
- Field rewarming should only be attempted if there is no further risk of refreezing. Tissue that thaws then refreezes results in more extensive injury.
- The decision to thaw the frostbitten tissue in the field commits to a course of action that may involve pain control, maintaining warm water baths at a constant temperature, protecting tissue from further injury during rewarming and eventual transport.
- In extreme circumstances, it may be better to let a casualty walk on a frozen limb to safety rather than risk refreezing.
Immediate hospital care
- The standard approach to the initial treatment of frostbite is the strategy originally outlined by McCauley and Heggers as mentioned below:
- Admit frostbite patient to specialist unit if possible
- Evaluate for hypothermia, concomitant injury, or complicating problems
- On admission, rapidly rewarm the affected areas in warm water at 37–39uC (99–102uF) for 15–30 mins or until thawing is complete
- Debride clear or white blisters and apply topical aloe vera (Dermaide aloe) every 6 h
- Leave haemorrhagic blisters intact and apply topical aloe vera every 6 h
- Splint and elevate the extremity
- Administer antitetanus prophylaxis (toxoid or immunoglobulin (Ig))
- Analgesia: opiate (intravenously or intramuscularly) as indicated
- Administer ibuprofen 400 mg orally every 12 h
- Administer benzyl penicillin 500 000 U every 6 h for 48–72 h
- Administer daily hydrotherapy in 40uC water for 30–45 mins. Do not towel dry affected tissue.
- Prohibit smoking
Fluids
- Rehydration can be provided orally or intravenously depending upon severity and ability of the patient to accept oral fluids.
- High altitude increases the risk of dehydration. If the patient is also hypothermic, dehydration may be compounded by cold diuresis due to suppression of antidiuretic hormone which necessitates correction with warmed intravenous fluids.
Rewarming
- Hypothermia and concomitant injury should be thoroughly evaluated.
- Systemic hypothermia should be corrected to a core temperature of 34°C before frostbite management is attempted.
- Rewarming should be carried out in a whirlpool (recirculating water) with a mild antibacterial agent (povidone-iodine or chlorhexidine).
- The State of Alaska Cold-injury Guidelines recommend a lower temperature waterbath of 37–39°C which decreases the pain for the patient while only slightly slowing rewarming.
- The time period recommended for rewarming varies from 15–30 mins up to 1 h.
- Rewarming should continue until a red/purple colour appears and the extremity becomes pliable.
- Active motion during the rewarming period is beneficial but care should be taken to prevent the extremity from touching the sides of the whirlpool.
- It is important to provide good analgesic cover and is likely to include narcotic medication.
Blisters and dressings
- Blisters containing clear or milky fluid should be debrided and covered in aloe vera, a potent anti-prostaglandin agent, every 6 h.
- Splinting, elevating, and wrapping the affected part in a loose, protective dressing should follow the administration of the aloe vera cream.
- Padding should be put between the patient’s toes if affected.
- Haemorrhagic blisters should be left intact to prevent desiccation of the underlying tissue. If they restrict movement they can be drained with their roofs left on.
Antibiotics
Tetanus toxoid
Analgesia and NSAIDs
Definitive treatment
- Angiography and thrombolysis
- Vasodilators: Iloprost
Surgery
Tissue protection
Adjuvant therapies
- Hyperbaric oxygen therapy
- Sympathectomy
Telemedicine
Primary Prevention
- As in many instances, it can be prevented so the key is deterrence and patient education.
- Risk modification including proper clothing, access to shelter, and maintaining hydration and nutrition are vital for protection against frostbite.
- Patients should be advised to carry extra clothing supplies if they are into winter sports and avoid tight restrictive clothing.
- Emollients, although traditionally believed in Nordic countries to prevent frostbite, do not have protective effects in preventing frostbite and should be discouraged.
- Advise against the use of alcohol, illicit drugs, and tobacco.
- For those with medical problems, it is important to ensure that their health is stable before venturing on an outdoors trip during winter.
- Prolonged exposure to freezing or cold temperatures may cause serious health problems so if signs related to it are observed, call for emergency help.
- The Occupational Safety and Health Act (OSHA) Cold Stress Card provides a reference guide and recommendations to combat and prevent many illnesses and injuries. Available in English and Spanish, this laminated fold-up card is free to employers, workers and the public.
- Tips include how to protect workers:
- Recognize the environmental and workplace conditions that may be dangerous.
- Learn the signs and symptoms of cold-induced illnesses and injuries and what to do to help workers.
- Train workers about cold-induced illnesses and injuries.
- Encourage workers to wear proper clothing for cold, wet and windy conditions, including layers that can be adjusted to changing conditions.
- Be sure workers in extreme conditions take a frequent short break in warm dry shelters to allow their bodies to warm up.
- Try to schedule work for the warmest part of the day.
- Avoid exhaustion or fatigue because energy is needed to keep muscles warm.
- Use the buddy system - work in pairs so that one worker can recognize danger signs.
- Drink warm, sweet beverages (sugar water, sports-type drinks) and avoid drinks with caffeine (coffee, tea, sodas or hot chocolate) or alcohol.
- Eat warm, high-calorie foods such as hot pasta dishes.
- Remember, workers face increased risks when they take certain medications, are in poor physical condition or suffer from illnesses such as diabetes, hypertension or cardiovascular disease.
References
Related Chapters
Template:Consequences of external causes cs:Omrzliny de:Erfrierung eo:Frostiĝo he:כוויית קור it:Congelamento lt:Nušalimas nl:Bevriezing (medisch) fi:Paleltuma sv:Köldskada