By: M.A Jafari MD EM Specialist Shahid Sadoughi Hospital

Transcription

1 By: M.A Jafari MD EM Specialist Shahid Sadoughi Hospital

2 Cold weather was an important factor in second world war.

3 Factors Influencing the Likelihood of Cold Injuries Temperature, Cold acclimatization, Duration of exposure, Alcohol use, Wetness, Use of protective ointments, wind, Constrictive clothing, Contact with cold objects or liquids 2 to 3 seconds metal touching < 15 C = Frostbite Gender, Raynaud phenomenon, Peripheral vascular diseases, Age, Diabetes, Race, Peripheral neuropathies,

4 Nonfreezing Cold Injuries: -Trench foot and immersion foot -Chilblains or pernio -Panniculitis -Cold urticaria Freezing Injuries: -frostbite

5 It was diagnosed among World War I troops confined in trenches filled with standing cold water Immersion foot is a more severe variant of trench foot seen in downed pilots and shipwrecked sailors exposed for extended periods in life rafts Nowadays, trench foot is occasionally seen in workers, in victims of shipwreck, in those in military training, and in persons who have been camping Pathophysiology: Prolonged cooling accelerated by wet conditions: lower the skin temperature, which leads to vasoconstriction, red cell and thrombocyte plugging, tissue edema, and nerve and small-vessel injury

6 Clinical Features: Early symptoms: tingling to numbness of the affected tissues. On initial examination: the foot is pale, mottled, anesthetic, pulseless, and immobile After rewarming: A hyperemic phase, edema and possibly bullae formation Hyperhidrosis and cold sensitivity are common late features Treatment: Supportive, but vasodilator drugs may be tried Feet should be kept clean, warm, dryly bandaged, elevated, and closely monitored for early signs of infection Oral prostaglandins: PGE1 (Limaprost) 20mcg TDS Nifedipine 20 mg TDS

7 Caused by long-term, intermittent exposure to damp, nonfreezing ambient temperatures The most common areas affected by chilblains are the hands, ears, lower legs, and feet Early symptoms: tingling to numbness of the affected tissues. The cutaneous manifestations: localized edema, erythema, cyanosis, plaques, nodules, and, in rare cases, ulcerations, vesicles, and bullae Chilblains is primarily a disease of women and children Raynaud phenomenon and other immunologic abnormalities are at greatest risk.

8 Rewarming may result in the formation of tender blue nodules, which may persist for several days Management: is supportive The affected skin should be rewarmed, gently bandaged, and elevated Some European studies support: Nifedipine, 20 milligrams PO TDS Pentoxifylline, 400 milligrams PO TDS, or an analog of PGE1, limaprost, 20 mcg PO TDS Topical corticosteroids (0.025% fluocinolone cream) and even a brief burst of oral corticosteroids, such as prednisone, have been shown to be useful.

9 Panniculitis is characterized by mild degrees of necrosis of the subcutaneous fat tissue that develops during prolonged exposure to temperatures just above freezing It is observed in children and on the thighs and buttocks of young women involved in equestrian activities During resolution of the mild inflammation, adipose fibrosis may result in cosmetic defects, such as unevenness of the skin There is no effective treatment for the injury

10 Cold urticaria is a distinctive example of hypersensitivity to cold air or water, which in rare cases may lead to fatal anaphylaxis Cold urticaria has been associated with increased affinity of Ig E to mast cells and viral infections, but most cases are idiopathic The diagnosis can be confirmed with the cold water test during follow-up Cold urticaria is treated similarly to urticarial lesions from other causes Antihistamines are recommended for acute cases (ketotifen)

11 Pathophysiology: The affected areas: head (31% to 39.1% of cases), hands (20% to 27.9%), and feet (15% to 24.9%). As the skin T drops to 14 C (57.2 F), the basal skin blood flow falls from 200 to 500 ml/min to 20 to 50 ml/min Hunting reaction or hunting response: As cooling to 10 C (50 F), cutaneous blood flow becomes negligible, with occurrence of 5-10 min cycles of vasodilatation and vasoconstriction As T fall well below 0 C (32 F), ice crystals form in the extracellular space causing increased osmosis, thus pulling fluid from the intracellular space. This results in cellular dehydration and hyperosmolarity. The intracellular sodium concentration may increase 10-fold Then intracellular ice crystals form, producing structural damage to the cell

12 After thawing, the damaged endothelium-lined capillaries allow leakage of fluid into the interstitium, intracellular swelling occurs, and oxygen-free radicals are generated Three zones of frostbite: The zone of coagulation: is the most severe and is usually distal, and the damage is irreversible. The zone of hyperemia: is the most superficial, is typically proximal, has the least cellular damage, and generally recovers without treatment in <10 days. The zone of stasis: is the middle ground and is characterized by severe, but possibly reversible, cell damage. It is this middle zone for which treatment may have benefit if the circulation in the frozen area can be restored

13 1st degree(frostnip): Partial skin freezing, erythema, mild edema, lack of blisters, and occasional skin desquamation several days later. Prognosis is excellent. 2nd degree: Full-thickness skin freezing, substantial edema, erythema, and formation of clear blisters. Prognosis is good. 3rd degree: Extends into the subdermal plexus, Hemorrhagic blisters, feels like a "block of wood, Prognosis is often poor. 4th degree: Extension into subcutaneous tissues, muscle, bone, and tendon. There is little edema. The skin is mottled, with cyanosis.prognosis is extremely poor.

14 Second-degree frostbite in the hand with blisters

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21 Prehospital Care: Prevention of further cold injury, In mild and conscious cases, warm drinks can be administered Dry heat may cause further injury and should be avoided Thawing should not, until the risk of refreezing is eliminated Frozen extremities should be immobilized, elevated, and handled gently Locally applied creams should not be used in the field

22 Rapid rewarming: Immersion in or application of water at 40 C 42 C until affected area is pliable and erythematous(20-30min). Parenteral narcotics for pain management Debride clear blisters ( PG & TXA 2 ). leave hemorrhagic blisters intact. Topical aloe vera cream every 6 h (arachidonic acid cascade). Affected digits should be separated with cotton and wrapped with sterile, dry gauze. Elevation of the involved extremities helps decrease edema and pain.

23 Infection prophylaxis: Penicillin G, 500,000 units IV every 6 hours for 48 to 72 hours Topical bacitracin may be as good as or better than IV penicillin(complicate the concurrent use of aloe vera) Tetanus immunization status should be assessed, because frostbite is considered a tetanus-prone wound Ibuprofen, 12 milligrams/kg/d PO, in divided doses (arachidonic acid cascade ) Extensive and prolonged physical therapy is usually required

24 Hypothermia Definition: body core T <35 o C (95 o F). Mild Hypothermia: (32-35 o C) excitation stage. Shivering, tachycardia, elevated BP. T<32 o C: -shivering ceases. -HR, BP, C.O & RR fall. -Mentation slows. -Loss of cough & gag reflex=> aspiration. -Impaired renal concentrating ability=> Cold diuresis resulting dehydration.

25 ECG Changes in Hypothermia T inversion. PR, QRS, QT prolongation. Muscle tremor artifact. Osborne J wave. Dysrhythmias: -Sinus tachycardia. -AF or Flutter. -AV block. -VF. -Sinus bradycardia. -Nodal rhythms. -PVC. -Asystole.

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27 ED Care & Disposition Mild Hypothermia: Passive rewarming: remove from cold area + insulating blankets.

28 ED Care & Disposition More Severe Hypothermia: ABC & initial resuscitation. Pulse oximetry, cardiac monitoring & continued core T monitoring. If no cardiovascular instability: active external warming.( radiant heat, warmed blankets, warm water immersion) Warmed IV fluids + warmed humidified O 2.

29 ED Care & Disposition More Severe Hypothermia: If cardiovascular instability is present: more aggressive active core rewarming (gastric, peritoneal, & pleural lavage with 42 o C fluid.)

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