Download Electrical burns

Pathophysiology of the burn wound
• Skin biology
• Pathophysiologic changes with thermal injury
Skin biology
Epidermis
• Multifunctionality:
– Barrier function
– UV protection
– Immune responses
• Five keratinocyte layers
– Stratum basalis (regenerative), stratum spinosum, stratum
granulosum, stratum lucidum, stratum corneum (barrier function)
• Melanocytes
– Produce melanin for ultraviolet protection
• Langerhans cells
– BM derived antigen presenting cells with phagocytic capability
• Sensory nerves
Skin biology
Basement membrane
• Basement membrane
– Connects epidermis to dermis via epidermal
projections
• Keratinocyte-derived collagen VII anchoring fibrils
anchor epidermis to dermis
– Following epithelialization, fibril formation may
take weeks to months to mature with increased
risk for shearing and blistering
– Rete ridges and dermal papillae also
contribute to epidermal-dermal adhesion
Skin biology
Dermis
• Heterogeneous layer of skin with multiple functions:
– Mesenchymal elasticity and durability
– Vascularity
– Immunity
• Two basic layers separated by a vascular plexus
– Superficial papillary dermis
– Deep reticular dermis
Pathophysiologic changes of
thermal injury
– Jackson’s zones of Injury
• Zone of coagulation (center of wound)
• Zone of stasis (‘at risk’ for conversion)
• Zone of hyperemia (outer periphery)
Jackson’s 3 zones of injury on an ankle burn: (a) the zone of
coagulation; (b) the zone of stasis, and (c) the zone of hyperemia.
Assessment of burn depth
1st-degree burn
• Superficial burn
– Epidermis only
– Heals in 3–4 days
– e.g. sunburn
Assessment of burn depth
2nd-degree burn
• Superficial dermal burn
– extends into the papillary dermis
– pink/moist wound, hypersensitive and blanching
– heals in 2–3 weeks
– e.g. scald burn or flash burn
• Deep dermal burn
– extends into reticular dermis
– pale/dry wound, decreased sensation, and sluggish capillary refill
– if not healed by 3 weeks grafting usually indicated
– e.g. grease burn, flash burn, prolonged scald exposure
Lower extremity burn having components of a superficial
dermal burn (a) with a wet, pink and moist appearance, as well as a
deeper
dermal burn; (b) with mottled pink and white areas.
Assessment of burn depth
≥ 3rd-degree burn
• Full thickness burn
– Extends through the skin to the SQ or deeper
– Black or charred, leathery, insensate
– Excise and graft early to reduce risk of infection and
scarring
– e.g. flame burns, contact burns
Deep contact burn in an elderly patient who was unconscious
next to a space heater. Arrows denote the imprints of the space heater
grill on his lateral thigh.
Assessment of burn depth
Adjuncts to clinical judgment
• Experienced burn surgeon 46–67% accurate in
determining which burns will heal on PBD 1
• Additional techniques proposed to identify nonhealing wounds:
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laser Doppler imaging
thermography
MRI
biopsy
ultrasound
light reflectance
• No technique has proven superior to serial exams
Mechanisms of thermal injury
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Flash and flame burns
Scalds
Contact burns
Chemical burns
Electrical burns
Mechanisms of thermal injury
Flash and flame burns
• Responsible for more than half of burn injuries
• Etiology
– House fires
– Outdoor fires with use of accelerants
• propane, gasoline, and kerosene
• 28% related to alcohol use
• Flash burn
• Typically superficial to partial dermal burns with
preservation of skin covered by clothing
• Flame burn
– Typically deep dermal or full thickness burns
• Inhalation injury likely with gasoline fire and/or house fire
Mechanisms of thermal injury
Scalds
• Second most common burn injury-related admission
• Depth of scald injury depends on
– Water temperature (>110ºF)
– Duration of contact
• consistency of liquid (i.e. soup vs coffee vs grease)
– Skin thickness
• based on age and anatomical location
• Clothed areas may have deeper burns due to retention of
heat and longer contact with skin
– e.g. diapers or socks
• Other sources of scald burns
– Grease/oil
• typically deep dermal or full thickness burns
Mechanisms of thermal injury
Contact burns
• Typically small areas due to hot metal, plastic, glass or
coals
• Burn depth related to
– Temperature of material
– Duration of contact
– Patient-related disabilities (e.g. neuropathy)
• Commonly responsible for pediatric palm burns
• Grafting of palm can lead to life-long disability and timing
of surgery is controversial
– Early grafting restores function quickly but destroys unique
palmar nerve endings and palmar fasciocutaneous ligaments
Mechanisms of thermal injury
Chemical burns
• Acids cause tanning with impermeable barrier limiting deep
penetration
– e.g. cleaning solvents
– Hydrofluoric acid burns unique in need for calcium treatment
• Topical
• Intravenous – for life-threatening hypocalcemia
• Intra-arterial – for comfort and hypocalcemia
• Alkalis combine with lipids (saponification) and dissolve tissue
– e.g. cement or drain openers
• Etiologies
– Work-related
– Assault
– Improper use of household products and harsh solvents
• Progressive damage diluted with copious H20 irrigation
– 15–20 minutes
– pH test of skin until neutral
– Attempts to neutralize causes exothermic reaction and thermal injury
Mechanisms of thermal injury
Electrical burns
• Due to very high intensity localized heat as body becomes an
‘accidental’ resistor
• High voltage injuries (>1000 volts)
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many work-related
deep tissue necrosis
arrhythmia (typically atrial fibrillation)
cognitive deficits
acute and delayed neuromuscular degeneration
• carpal tunnel injuries
• compartment syndromes
• early surgical intervention indicated for acidosis ± signs of
rhabdomyolysis or deterioration of neuro-sensorimotor exam
– cataract formation
• Low voltage injuries (<440 volts)
– Typically small deep burns at contact points with rare systemic injury,
– Classic pediatric injury involves oral commissure with risk of delayed
oral artery bleed
Criteria for transfer of a burn
patient to a burn center
• Second-degree burns greater than 10% total body surface area
• (TBSA)
• • Third-degree burns
• • Burns that involve the face, hands, feet, genitalia, perineum, and
• major joints
• • Chemical burns
• • Electrical burns including lightning injuries
• • Any burn with concomitant trauma in which the burn injuries
• pose the greatest risk to the patient
• • Inhalation injury
• • Patients with pre-existing medical disorders that could complicate
• management, prolong recovery, or affect mortality
• • Hospitals without qualified personnel or equipment for the care of
• critically burned children.
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Guidelines for referral to a burn center
Partial-thickness burns greater than 10% TBSA
Burns involving the face, hands, feet, genitalia, perineum, or
major joints
Third-degree burns in any age group
Electrical burns, including lightning injury
Chemical burns
Inhalation injury
Burn injury in patients with complicated pre-existing
medical disorders
Patients with burns and concomitant trauma in which
the burn is the greatest risk. If the trauma is the greater
immediate risk, the patient may be stabilized in a trauma
center before transfer to a burn center.
Burned children in hospitals without qualified personnel for
the care of children
Burn injury in patients who will require special social,
emotional, or rehabilitative intervention