Lecture №25 Thermal injuries (сo)

7/31/2019 Lecture 25 Thermal injuries (o)

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2) The depth of injury:partial- and full-thickness burns. Partial-thickness

burns (first- and second-degree) damage variable amounts of the dermis

and dermal appendages. Full-thickness (third-degree) burns result in

complete epidermal and dermal destruction.

Partial thickness burninvolves the outer layer of the skin and may extend to

the dermis (first and second degree burns):

blistering

the skin is red and moist

painful to touch

sensation is intact

First degree burn

Partial thickness burn is further subdivided into superficial and deeppartial-

thickness injury. The clinical differentiation is difficult (by the time of

healing, laser doppler flowmetry).

superficial partial-thickness burn should heal within 2 weeks (minimal

cosmetic and functional consequence).

deep partial-thickness wound (cosmetic deformity and disturbance of

function) takes 3 weeks to reepithelize. In this case skin grafting will

improve the outcome and is preferred approach in this depth of injury.

Second degree burn

Partial-thickness burn

Burned buttocks in a child (scold)


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Full-thickness wound

leathery

white or charred

dry

insensate.

All dermis is destroyed. During healing a contraction occurs decreasing the areabut leading to poor cosmetic results and joint stiffness.

Except for small surface area wounds, full-thickness wound should be eitherexcised and closed primary or grafted with the patients skin.

Third degree burn

Types of wound

Thermal burnresults in superficial area of coagulation necrosis.

temperature

duration of exposure

thickness of tissue

blood supply of the tissue

Chemical burnscause denaturation of proteins.

The degree of injury depends on:

time of exposure

Types of wound

strength of the agent

solubility of the agent in tissue

Alkali tends to penetrate deeper into tissue then does an acid.

Ingestion of chemical agentleads to esophageal injury (laterconsequences include development of strictures). Besidelocal effects of chemicals they also may exert systemiceffects (especially phenol, mustard gas). Phenol burns canbe treated with lipophylic solvents such as polyethyleneglycol or glicerol.

Types of wound

Electric injury:the surface injury is often not indicative of the extend of injury.In the local area of injury a subcutaneus tissue, muscle, and bone may bedamaged. Electrical current passes through the path of least resistance betweenthe entrance and exit point (nerves and blood vessels)

.initiated immediately (ECG monitoring).

Fluid resuscitation as in burned patients.


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Nephron structure. Myoglobinuric renal failure. Renalbiopsy of a patient who hadrhabdomyolysis and myoglobinuricARD. Coarse eosino hilic casts of

At the small point of contact the skin is charred. It may overlie extensive areasof devitalized muscles: liberation of mioglobin ARF (if an adequate UO isnot maintained).

myoglobin are evident in the tubularlumen.

Edema formation in injured tissue beneath fascia may increase musclecompartment pressure and compromise blood supply. Fasciotomyshould beperformed.

Fasciotomy. The anterior and lateral compartments are decompressed through a

lateral incision. The skin incision is placed just anterior to the fibula and the skin

is undermined anteriorly and posteriorly to expose these two separate

compartments. The incision on the medial side of the leg opens the superficial

posterior compartment. At a deeper plane, the deep compartment is then released.

Etiology: aldehydes, carbon monoxide and cyanide. Pathology: erythema, edema,blistering, ulceration, erosion, and sloughing in the airway endobronchial cast andobstruction of the bronchioles obstruction and accumulation of the necrotic debris (dueto injury of the mucocilliary transport mechanism) poor ventilation and ground forinfection (70% within a week of injury).

Inhalation injury

Pathologic response of the lung

to inhalation of smoke.

Inhalation injury

Diagnosis:based on the history, signs and symptoms.

Assume inhalatory injury in:

injury in closed space

has burns above the clavicle

s nge ng o nasa v r ssae

hoarseness

carbonaceous sputum


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Inhalation injury management

Airway evaluation (at emergency department) using flexiblebronchoscopy. It confirms diagnosis and helps to insert an

endobronchial tube if necessary (tube is passed over thebronchoscope before the endoscopy).

Therapy is not specific (the injury is not quantified by testing - X-ray, respiratory testsare not helpful)

aggressive pulmonary toilet use of mucolytics

early identification and treatment of infection

Inhalation injury management

prop y ax s w t s not use

steroids are of no benefit and are potentially harmful.

Nasotracheal suctioning to clear the

upper airway. If frequent suctioning

is required a soft rubber

nasopharyngeal trumpet may be

placed to minimize trauma.

Prehospital and emergency room care

Scene of the injury remove the patient from heat extinguish burning cloth

remove from electrical contact ice or cold water soaks to decrease ain burns less than 25% of TBSA ,

and reduce tissue heat content (if applied within 10 minutes after injury).

Cardiopulmonary function - CPR., i.v. line is necessary at patients withcardiac irregularity, massive blood loss (coexisting trauma), and if thetransport takes longer 30 min .

Inhalation injury:

Carbon monoxide poisoning (closed space injury) - administration of 100%oxygen.

An endotracheal tube (airway protection) is needed to patients with severeinhalation injury.

Patient with burns more than 30%, those of the extreme of age and those withthe significant preexisting disease should by cared for in burn centers.

Resuscitation

i.v. fluid replenishment through venous cannulation

nasogastric tube to decompress the dilated stomach

patients are wrapped in clean sheets or blankets resuscitative fluids should be warmed

burn-injured extremities should by elevated above the level of theheart.


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Resuscitation

The first 24h: crystalloid solutions. The amount is based on the patientresponse to resuscitation.

Administered solutions should maintain a normal: BP HR

UO (1ml/kg/h or 30-50ml/kg). maintenance of mean arterial pressure at 60mmHg (requires IAL)

measurement of blood lactate levels (requires IAL)

Goodwin formula: 3ml/kg per percent of the body surface area is burned.

Parkland formula: 4ml of LR/ kg / % of burn surface.

e secon : co o -conta n ng so ut ons

Evaporative loss (25+% of burned area) multiplied by total body surface areain square meters (100%). This formula is used for fluid replacement at thefollowing days.

Initial wound care

Burned area small blisters are left intact larger blisters and full-thickness burns: debridement and topical agent.

Chemical injury irrigation (normal saline or tap water) for as long as 6h.

Prophylaxis against wound infectionSystemic antimicrobial prophylaxis is not used (only if infection has

occur).

Commonly used topical agents: silver sulfadiazine (prophylaxis against infection but not for therapy) aqueous solution of silver mefenide acetate.

Surgical wound care

Excision and closure of wounds (is best done when the patient has beenstabilized and within 3 to 4 days after injury) using:

a) tangential excisionuntil viable tissue (preferred);

b) excision of the wound to the level of fascia(for deep full-thickness and infected).The cosmetic results are poor and lymphatic drainage is impaired .

Consider the skin donor sites at patients with deep partial and full-thickness burnsmore than 40% bod the re uire skin raftin .

Autograft (for ultimate closure).a) sufficient donor sites - split-thickness autograft or full-thickness graft.

b) donor sites are limited - autograft can be expanded (mashing device).

Cuttong a split skin graft. The graft is taken from normal thigh skinCuttong a split skin graft. The graft is taken from normal thigh skin


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Full-thickness burn wounds covered by mesh grafts. Mashing increases

the area of the skin grafts and allows blood and exudate to escape thus

minimizing hematomaTemporary coverage with biological or manufactured dressing

Temporary skin substitutes

allograft skin from cadavers (free of jaundice, cutaneus malignancy and viraldisease).

synthetic membranes (Biobrand, Silastic).

autologus keratinocytes skin substitutes: Integra artificial skin, Alloderm (that is a human dermis with

nonantigenic matrix provides a scaffold for a new dermis on which a thinepidermal graft may be placed.

Pigskin, Biograne, TransCyte, etc.

Allograft can be used no longer than 7 days

Circumferential burns

A full-thickness burn injury possesses a risk of compressionand compromise of blood flow:

elevate extremity to reduce edema

evaluated hourly for signs of vascular compromise (pallor,pain, parastesia, paralysis, pulse)

Doppler examination

An escharotomy is an incision done through the eschar.

If escharotomy does not restore blood flow a fasciotomy is required.Preferred sites for escharotomy incisions (dashed lines). The solid portions of

the lines demonstrate the importance of extending the incision across joints in

areas of full-thickness burns.


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Tetanus prophylaxis

Evaluate patient's immunization status.

Burned atients who have under one revious activeimmunization within 5 years of the time of injury requireno further prophylaxis.

Patients who have received their most recent boosterinjection more than 5 years before injure should beadministered a booster dose of toxoid.

Patients who have not undergone prior immunization or

w t out story o mmun zat on s ou e g ven -units of human antitetanus globulin at one site and initialimmunizing dose of toxoid administered at another site.

Prognosis

Risk scoring system in which one point is given for each of

burn size greater than 40% of TBSA

age greater then 60 years

presence o n a atory n ury

Mortality rate 0,3% with no risk factors

3% with one risk factor

33 % with two risk factors

90% three factors

The system does not consider preexisting pathology, stratification of age andextend of injury.

Later consequences

Burn scar contracture and hypertrophic scarring. Especially dangerous at the

joint area.

The treatment of hypertrophic scars withpressure garment. A typical example

of active hypertrophic scaring following a full-thickness scald. Pressure

garments were worn continuously for 14 months and the scar matured with

reduced contracture formation.

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Z-plastyis used to relief scar contractureMethods of releasing burn scar contractures. The fish-tail incision and

graft method of releasing broad contractures.

Frostbite

Pathology:

, ,

cellular dehydration, and microvascular occlusion.

Epidemiology: poor clothing during winter months

acute alcoholism

psychiatric illness

Classification (depth of frostbite) and clinical presentation.

First degree: hyperemia ant edema;

Second degree: hyperemia ant edema with vesicle formation (partial-, .

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Third degree: necrosis of entire skin thickness, formed vesicles mach smaller

than those with second degree frostbite.

Fourth degree: full-thickness necrosis of the skin and extends into underlying

muscle and bone.

After thawing Mild injury : capillary flow restores. Area is red and warm with throbbing

pain (arterial pulsation), sensation and motor function return. Largevesicles appear within few hours, are filled with straw-colored fluid. Mostof these changes resolve in 1 to 2 weeks with little or no tissue loss.

Severe frostbite: ca illar flow is never restored arteriovenous shuntinthe injured area is cold and deep red. A patient is still able to move thedistal parts. Extensive edema may persists for months. Eventually thenonviable skin and deep structures demarcate and mummify.

Most cases of frostbite are between the two extremes described.

Determination of tissue viability is impossible during the first severalweeks following injury and often can be made only after gangrenoustissue has demarcated and sloughed.

Treatment

remove constricting clothes

wrap in warm blankets

rewarming (40 C0 20 to 30 minutes).

Local care

Prevention of infection

vesicles are left intact (not leaking or infected)

bed rest

wounds are exposed to the air

foot cradle

lamb's wool is inserted between affected digits

cleansed daily with an AB solution in a whirlpool bath use of pressure dressing is contraindicated.

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Surgery must be delayed until clear demarcation. (may require several weeks)

Wet gangrene requires immediate surgical removal of the source of sepsis.

Tetanus prophylaxis is based on the patient's prior immunization status. Antibiotics are indicated when infection is evident.

In the rare situations in which a large volume of tissue has been frozen massivefluid loss may require i.v. fluid resuscitation.

Chronic postfrostbite sequelae: hyperhidrosis, paresthesias, cool extremities,n v y, an ma. urg a v n gm n ym a run

provides long-term relief.

The Alaskan algorithm for treatment of frostbite.

Lecture №25 Thermal injuries (сo)

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