Acute Burn

8/10/2019 Acute Burn

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ACUTE BURNDr. Mgs. Roni Saleh, SpB-

SpBP(K)


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I. Phatophysiology

A. The severity of the burn is determinedby temperatur and length of exposure tothe heat source.

B. Skin has a large water conten; therefore,it overheats slowly and cools slowly.

C. Heat continues to penetrate deepertissue layers even after the external heat

source is removed. Immediate coolingmay reduce underlying tissuetemperature, but it has a limted role inlarge burns because it may reduce the

patients core temperature.


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I. Pathophysiology (Contd)

D. Three areas of injury1. Central zone of coagulation: Nonviable,

irreversibly injured tissue.

2. Middle zone of stasis: Initially characterizedby dilated blood vessels and capillarydiffusion. After 24 to 28 hours, dilatedcapillaries become occluded, with resultingconversion of this zone of tissue tocoagulation. Injury in this zone may bereversible with appropriate treatment(cooling, fluid resuscitation, critical care).

3. Outer zone of hyperemia: Composedmostly of viable, edematous tissue.


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I. Pathophysiology (Contd)

E. Progressive changes in microcirculation1. There is an initial, sudden decrease in blood

flow.

2. Arteriolar vasodilation follows.

3. Increase capillary permeability leads toederma formation, which is greatest at 8 to12 hours.

4. Endogenous mediators (histamine, serotonin,

kinins) increase capillary permeability,leaking protein into the intersitial space.

5. Hypoproteinemia decreases intravascularoncotic pressure, resulting in a shift of fluidinto the interstitium (i.e., third spacing)


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II. Initial management

A. History

1. Identity the source: Hot liquid,chemicals, flame, superheated

air/steam, explosion, etc.

2. Duration and location of exposure:Closed space; potential for smoke

inhalation3. Concomitant drug or alcohol ingestion

4. Associated injury mechanism:Esplosion, jump/fall, motor vehicle

crash, etc.


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II. Initial Management (Contd)

B. Airway and breathing1. Early intubation

a. Frequently necessary to prevent airway

obstruction due to progressive airwayedema.

b. Most patients with extensive (>50%)burns requre intubation

c. Use humidified oxygen.

2. Chest and abdominal wall burns canseverely limit chest wall excursion andimpair ventilation. Escharotomies maybe necessary


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C. Circulation1. Intravenous access: Ideally, several peripheral large-

bore intravenous lines should be place throughnonburned tissue. Central lines are the next bestoption.

2. Intravenous fluid administrationa. Isotonic salt solutions are used for resuscitation and

maintenance.b. Glucose should be avoided. Burn patients are frequently

glucose intolerant and hyperglycemic due to the stressresponse. The resulting osmotic diuresis can lead tospuriously high urine output.

D. Disability : A rapid, thorough baselineneurologic examination should be performed.This is especially important in the setting ofblunt trauma, head injury, carbon monoxideexposure, and/or the need for sedation.


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E. Initial wound care1. Stop the burning process

a. Flame burns: smoldering or burning materials must be extinguished andremoved, since they can retain heat and exacerbate the burn injury.Irrigate the wounds with normal saline if any foreign material remains.

b. Chemical burns: Remove all clothing and begin gentle, copious irrigationwith warm normal saline. Avoid the use of neutralizing solutions.

2. Cover: Clean, dry, nonadherent dressings are used to protect thewound and prevent hypothermia.3. Analgesia.4. Tetanus prophylaxis.5. Prophylactic intravenous antibiotics are notindicated.6. Criteria for admission to a burn center.

a. If 10 to 40 years old: Greater than 15% total body surface area (TBSA)

second-degree burns or greater than 3%. TBSA third-degree burnsshould be treated on an inpatient basis.b. If younger than 10 years or older than 40 years: Greater than 10% TBSA

second-or third-degree burns.c. Burns involving the face, hands feet and/or perineumd. Circumferential extremity burns.e. Electrical burns


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III. Inhalation Injury

A. Etiology1. Chemical irritants in smoke affect the distal

airways, resulting in an intense inflammatoryresponse, which can lead to adult respiratory

distress syndrome (ARDS) and/or systemicinflammatory response syndrome (SIRS).

2. Direct thermal injury: inhalation ofsuperheated air or water vapor can cause athermal burn to the airway mucosa.

3. Oropharyngeal and supraglottic edemacaused by thermal injury can progress toairway obstruction


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III. Inhalation Injury (Contd)

B. Evaluation1. Maintain a high index of suspicion.2. Signs and symptoms

a. History of burn in a closed space

b. Presence of facial burns and/or oral carbondeposits.c. Singed facial hair/nares, hoarseness, or wheezing.d. Unconsciousness.

3. Nasopharyngoscopy: Can be used to directly

evaluate the larynx and vocal cords forinjury.4. Bronchoscopy: Via the endotracheal tube, if

symptoms warrant.


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III. Inhalation Injury (Contd)

C. Treatment1. Intubation, mechanical ventilation

a. Early intubation is essential. Patients withinhalation injury often present as conscious, awake,and comfortable initially. Upper airway edema can

progress rapidly to complete airway obstruction.b. Ventilator management goals: Maximize

oxygenation while avoiding oxygen toxicity (keepFiO2


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III. Inhalation Injury (Contd)D. Carbon Monoxide (CO) poisoning

1. CO is generated by fire. When inhaled and absorbed, itpreferentially binds with hemoglobin, displacing oxygen andblocking oxygen binding sites, causing a substantialreduction in oxygen delivery.

2. Signs and symptomsa. Pulse oximetry is unreliableb. Cherry red skinc. Hypoxemiad. Mental status changes or a history of a loss of consciousnesse. Persistent acidosis in the presence of normovolemia

3. CO levela. May be normal or minimally elevated, even with significant

exposure.b. 20% to 40% Associated with severe neurologic symptoms.c. Greater than 60% Commonly fatal

4. Treatmenta. 100% oxygen administration: Displaces CO from hemoglobinb. Hyperbaric therapy: Consider if the patient is at risk for CO

exposure and has mental status changes


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IV. Burn Wound Assessment

A. Area

1. Patients palm is approximately 1 %ofTBSA

2. Adult: Rule of 9s

a. Arm, anterior/posterior legs, head = 9%each.

b. Anterior/posterior torso = 18% each

3. Children: The head has aproportionately larger surface area.


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(Contd)

B. Depth: Initial estimates may beinaccurate, since the depth of theburn can progress over time.

1. Superficial first degree

a. Example: sunburn

b. Confined to the epidermis

c. Skin: Mildly erythematousd. Pain: Resolves in 48 to 72 hours

e. No scarring


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(Contd)


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(Contd)


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(Contd)2. Partial Thickness-second degree

a. Entire epidermis and variable thickness of dermisb. Skin: painful, red, edematous, blisteredc. Superficial: Dermal appendages intact; heals in less than

3 weeks, usually with minimal to no scarringd. Deep: less pain, heals in weeks to months with scarringe. The most important distinction is between superficial and

deep partial-thickness burns, since excision and graftingis performed for deep partial-thickness burns, since andusually not for superficial partial-thickness injuries.

3. Full thickness third degreea. The epidermis and dermis are destroyed, no dermal

appendages remain, and there is no possibility ofspontaneous regeneration.b. Skin: Not painful. It has a leathery, waxy, charred

appearance with thrombosis of vessels.


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V. Fluid Resuscitation

A. No formula uniformly predicts fluidrequirements accurately for everypatient. The physician must repeatedly

assess each patients ongoingfluidrequirement to maintain anadequate circulatory volume. Allresuscitative endpoints (e.g., physical

examination, distalperfusion, urineoutput, central wedge pressure) areimportant.


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V. Fluid Resuscitation (Contd)

B. Modified Brooke (Parkland) formula1. First 24 hours requirement = 4 cc %TBSA X

patients weight (kg).2. Administer half of the above volume during

the first 8 hours (calculated from the time of

injury, not the time of hospital admission),and the other half over the next 16 hours.

3. The adequacy of resuscitation is best judgedby hourly urine output (30-50 cc/hr in adults,or 1 mL/kg/hr in children).

4. High-voltage electrical burns or deep tissueburns: There is a high risk for myoglobin-induced acute tubular necrosis.

a. Maintain urine output at 2 mg/kg/hr.b. Alkalinize the urine: add bicarbonate to intravenous

fluid (50 mEq/L).c. Monitor urine myoglobin levels


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V. Fluid Resuscitation (Contd)

C. Colloid administration : Notrecommended in the first 24 hoursafter a burn. Increased capillary

leak causes the colloid to becometrapped in the interstitial space,increasing third spacing and edema.

D. Hyponatremia and hyperkalemiaare common: Follow serialelectrolyte levels.


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VI. Burn Wound Care

A. Infection1. Bronchopneumonia is the leading

cause of death.

2. Burn wound sepsis, septicthromboplebitis, and bacterialendocarditis are also commoninfections in the burn patient.

3. Pseudomonas, Enterococcus, andmethicillin-resistant staphylococusarethe main offending organisms.


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VI. Burn Wound Care (Contd)

B. Topical antimicrobial agents

1. Silvadene (1% silver sulfadiazine)

a. Widely available.

b. Broad gram-negative and gram-positivecoverage.

c. Moderate wound penetration

d. Can damage the cornea

e. May cause leukopenia


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2. Sulfamylon (10% mafenide acetate)

a. Broad-Spectrum coverage

b. Excellent wound penetration

c. The best topical agent for exposedcartilage (e.g., the ear and nose).

d. Painful

e. Can cause acidosis due to carbonic

anhydrase inhibition. Its use should beavoided in burns greater than 20% TBSA.


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3. Silver nitrate (0.5% solution)

a. Broad-spectrum coverage.

b. Poor eschar penetration

c. Costly, messyd. Can cause hyponatremia

4. Bacitracin zinc ointment

a. Effective against gram-positive organisms

only.

b. Does not penetrate burn eschar

c. Commonly used for facial burns


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C. Excision and grafting1. Tangential burn wound excision and skin graft coverage is

performed following hemodynamic stabilization, oftenbeginning within 2 to 4 days of injury.

2. Tangential excisiona. Thin-layer sequential excision of all nonviable tissue until a

viable tissue level is reachedb. Skin grafting on fat can be tenuous due to its poor blood supply

and difficulty in delineating a healthy level.c. Delayed grafting

1) Performed in cases of inadequate donor sites for graft harvest2) Cover wounds first with cadaveric allograft or a nonbiologic dressing

to protect against fluid losses and burn wound infection.

d. Operative blood loss can be considerable. The recommendedlimit for excision in a single session is approximately 10 % to20% TBSA or less than 10 units of packed red blood cellstrasfusion.


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3. Grafting techniquesa. Graft thickness: Generally 12 to 14/1000th inch.

The thinner the graft, the more likely the take, butmore significant is the degree of secondarycontraction. Use 16 to 20/1000th-inch thickness

for the face, if possibe.b. Meshing : Usually at a 1:1.5 ratio. Meshing the

graft increases the surface area that can becovered, and can decrease hematoma and seromacollection beneath the graft. Higher mesh ratioscan be used, as necessary (e.g., 1:2, 1:3, or 1:4).

c. Unmeshed sheet grafts are typically used oncosmetic or functional areas, such as the face,breast, and hands.


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4. Graft failurea. Inadequate wound debridement prior to

graft application is the primary cause.

b. Infection

c. Seroma, hematoma

d. Lack of moisture

e. Shear: Improper padding, dressing, orpatient positioning.

f. Poor nutritional or overall physiologicstatus (e.g., poor visceral protein levels orsepsis).


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VII. Circumferential Burns

A. Circumferential burns: Result in limited ability forexpansion of tissues with edema. This can causesupraphysiologic pressures to develop, causing tissueischemia and necrosis.

B. Physical signs are often obscured by the burn injury ortissue edema. Doppler examination is unreliable in

estimating tissue perfusion.C. Burned extremities should be elevated.D. Escharotomy: incision of burned skin to relieve

constriction.1. Electrocautery incision is the method of choice, and can be

performed at bedside because the burned skin is anesthetic.

2. Arms and legs: Medial and lateral incisions; may includedigits.

3. Chest and upper abdomen: Bilateral midaxillary releases canbe connected with a horizontal incision to form an H.


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VII. Circumferential Burns (Contd)


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VIII. Burns of The Face, Eyes, And

EarsA. The central face has deeper skin appendages, resulting in

a greater healing capacity.B. Use unmeshed sheet grafts, applied by aesthetic units.C. Attempt to perform facial grafting less than 2 weeks from

the time of injury to decrease scarring.

D. Eyes: Lid edema usually protects the eyes in the earlystages. As edema subsides and wound contractionoccurs, keratitis and corneal abrasion are common risks.Temporary tarsorrhaphy and/or surgical release may berequired.

E. Ears: Twice per day sulfamylon application is thetreatment of choice. Avoid any external pressure to theear. Supurative chondritis requires urgent debridement.


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IX. Burns of The Hands and Feet

A. Always perform a complete hand examination.B. Maintain a low threshold for escharotomies and

fasciotomies, as these procedures save extremities.C. Superficial burns: Elevation, topical antimicrobials, and

passive range of motion for each joint twice per day.

D. Appropriate splinting is crucial to prevent contractures.E. Deep partial- and full-thickness burns: Early excision and

sheet g rafting are preferred. Immobilize for 5 days, thenstart occupational therapy

F. Palmar skin is thick. Only 20% of palmar burnsultimately require resurfacing. A conservative approach is

recommended to preserve thick fascial attachments.G. Burns of the feet are managed similarly to hand burns.


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XI. Nutrition

A. A hypermetabolic response is common with all largeburns.1. The metabolic rate is proportionalto the size of the burn, up

to 60% TBSA, remaining constant thereafter.2. This response begins soon after injury, reaching a plateau

by the end of the first week. Most burns of more than 30%TBSA require intensive nutritional support until wound

healing is complete.3. Energy expenditure is unpredictable.4. Harris-Benedict equation

a. 24-hour caloric requirement = (25 kcal X kg body weight) + (40kcal x %TBSA)

b. Frequently undercalculates the real metabolic needs.

B. Protein: 2.5 to 3 g/kg per day are recommended. Inchildren, requirements are 3 to 4 g/kg per dayC. Intestinal feeding should be performed early.D. Prealbumin levels are drawn to monitor adequate

nutrional progress in patients with large burns.


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XII. Electrical Injuries

A. Low-voltage injuries can be locally destructivewithout systemic sequelae

B. High-voltage injuries (>1,000 volts): Can resultin extensive internal destruction.

1. Entrance and exit wounds: Usually less than 10% to15% TBSA.

2. Deep tissue injury is cause by the passage of currentthrough tissue. The damage is analogous to amassive crush injury with intact skin

3. Injury is proportional to tissue resistance: bone >muscle > nerve.

4. A full trauma workup is paramount. Associated injuriesfrom a fall or tetanic contraction of muscles(paravertebral) are common.


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XII. Electrical Injuries (Contd)

C. Significant cardiac damage is extremelyrare. Cardiac monitoring should beinstituted during the first 24 to 48 hours.

D. Muscle damage

1. Should be suspected with myoglobinuriaand/or pigmenturia.

2. Maintain a high urine output.3. Apply Sulfamylon for eschar penetration4. Compartment syndrome.

a. Continually reevaluate the peripheral circulation.b. Measure compartment pressures with a Stryker

instrument or arterial line setup with a large-boreneedle (normal: 30 mmHg).

c.

Fasciotomy: Perform in the operating room


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XIII. Chemical Burns

A. Usually deeper than they appear.B. Injury is due to a chemical reaction rather than thermal

injury.C. In general, dilution, not neutralization, is the key to

management.D. Specific agents.

1. Hydrofluoric acida. Liquefaction necrosis in subcutaneous tissue and deeper .b. 10% calcium gluconate: Infiltrate subcutaneously after topical

dilution with water if pain persists. It is also available as atopical gel.

2. Phenola. Poorly soluble in water.

b. Has an analgesic effect.c. Some systemic absorption is possible, causing arrhythmias.d. Wash with polyethylene glycol if available.

3. White phosphorusa. Chemical and thermal burnsb. Copper sulfate: Facilitates removal of the particles (following

copious water lavage).


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Pearls

1. Use formulas only as a guide to fluidreplacement. Monitor fluid status on an ongoingbasis via urine output and other measures.

2. Be wary of inhalation injury and have a low

threshold for early endotracheal intubation.3. Have a low threshold for obtaining an

ophthalmologic evaluation for burns involvingthe face.

4. Watch for myoglobinuria and reanl failure inelectrical burns.

5. Look for circumferential burns and considerearly escharotomies.


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Acute Burn

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