Burns Flashcards
Function of the skin
- Protect from infection
- Senses (pain, touch, temp)
- Fluid control
- Temp regulation
- Insulation from trauma
Electrical burns
- Electrical contact with the skin (live electrical currents, lightning)
- Low voltage (damage only to point of contact and damage depends on exposure time)
- High voltage (damage runs full course and usually results in subdermal damage)
- Greatest heat at points of resistance (entrance and exit, dry skin, muscle & bone) & greatest damage with smaller points of contact
- Results in vascular & nervous damage, immobilisation of muscle
Chemical burns
Skin exposure to a corrosive substance
Acids: forms thick insoluble mass upon contact & causes coagulative necrosis that limits burn damage
Alkalis: destroys tissue by liquefactive necrosis therefore deeper penetration
Radiation burn
From transmission of radiation energy (nuclear, UV, visible, heat, sound, XR)
Thermal burns
Exposure to heat > 40C that causes protein coagulation and thrombosis (flames, scalds (liquids), vapours, contact)
* Flame most common in adults & result in the most deaths (many die from asphyxiation or CO poisoning before treatment)
* Scalds most common in children
Inhalation injury
Associated with thermal burns from fires
* Inhalation of toxic substances (cyanide, hydrogen sulfide)
* CO poisoning from burning carbon products (binds Hb and prevents O2 binding)
* Airway burn (upper airway structures absorb heat from steam and prevent damage to lower airway) - singed facial hair, black sputum, airway obstruction, stridor
Jackons theory of thermal wounds
Zone of coagulation: maximum damage, necrotic/dead tissue, clotted blood & thrombosed vessels
Zone of stasis: hypoperfused tissue at risk of ischemia
Zone of hyperemia: hyperperfused tissue, most salvagable
Superficial/1st degree
- Epidermal damage only e.g. sunburn
- Red, tender, pain, no blistering
- Heals within a few days, no scarring
Superficial partial/2nd degree
- Epidermis and superficial dermis damage
- Red, very painful, blisters
- Heal spontaneously within a few weeks without scarring
Deep partial/2nd degree
- Epidermis and deep dermis damage
- White/blotchy, less painful, no blisters
- Heal after 3-4 weeks and may scar depending on time taken for re-epithelialisation
Full thickness/3rd degree
- Entire dermis & subdermal tissue
- White/brown/black, eschar, lethery
- Do not heal spontaneously and may require surgical debridement and skin grafts, scarring will happen
Systemic pathophysiology
TBSA > 30% = systemic inflammatory response
* Inflammatory mediators lead to increased vascular permeability, causing fluid to shift into interstitial space
* Peripheral vasodilation also occurs
* These both cause major fluid loss, hypovolemia, decreased perfusion
* Perfusion is worsened by release of catecholamines, vasopressin and angiotensin which causes vasoconstriction of arteries supplying organs
* Respiratory distress from bronchospasms, pulmonary oedema & inhalation injury
* Hypothermia from disturbed thermoregulation, evaporative water loss from burned skin, cooling during treatment and cold resus fluids
* Inflammatory mediators and E imbalances from fluid shifts cause cardiac dysfunction & decreased contractility
Hypermetabolic phase
* surge of catecholamines, cortisol, glucocorticoids
* Increased metabolism, CO, HR, O2 requirements
* Insulin resistance & glucose production
* Protein breakdown & skeletal muscle wastage
* Immunosuppression & delayed wound healing
*
Clinical manifestations
- Pain
- Local damage (blisters etc)
- Burnt hair, black sputum
- Dyspnoea, hoarseness, wheezing/stridor
- Peripheral oedema
- Oliguria/AKI
- Reduced LOC
- Signs of hypovolemia (HoTN, tachy then brady)
- Arrythmia, chest pain
- Hypothermia
- Infection (local, pneumonia, UTI, sepsis)
TBSA Assessment
Wallaces rule of 9 (adults): divides sections into 9% for head, 9% each arm, 18% chest, 18% back, 18% each leg, 1% genitalia, 1% palms
Lund & browder (paeds): allows for changes in proportion in children e.g. head is proportionately larger & legs smaller (chart for each age)
NB: superficial burns not included
Patient Assessment
Airway: assess patency, signs of inhalation injury (burnt hair, sputum, stridor, inflammation), assess need to O2 tx & intubation
Breathing: full respiratory assessment, consider escharotomy for circumferential burns to allow chest expansion
Circulation: monitor HR & rhythm (ECG), BP (SBP >90, MAP > 65mmHg), SaO2, CRT, IV access & IDC insertion, commence fluid therapy, tranfusion if needed
Disability: GCS, NVO (circumferential burns compromise circulation/compartment syndrome), DVT prophylaxis, IV analgesia
Exposure: remove non-adherent clothing, assess for other injuries, estimate TBSA, wound care
Treatment
- Airway patency (intubation)
- Oxygenation
- Fluid resuscitation & IDC insertion
- Wound care & surgical debridement
- Analgesia
- Nutritional therapy - NGT: to aspirate fluid & air to prevent aspiration, nutritional feeding early to diminish hypermetabolic response & prevent bacterial translocation from gut (sepsis)
- Electrolyte management
Fluid resuscitation
Parkland formula: 4ml x TBSA x weight (kg) = 1/2 over 8 hours, 1/2 over 16
* Crystalloids (CSL) or colloids (albumin, gelofusin)
* Strict monitoring of UO to 0.5-0.5ml/kg/h to assess for signs of over resusciation and respiratory collapse
Primary purpose is to restore circulating blood volume lost during fluid shifts, in order to maintain organ and tissue perfusion
Escharotomy
- Circumferential burns increase interstitial pressure and compromise circulation & cause ischemia & compartment syndrome
- Indicated when there is a loss of doppler pulses & NV despite elevation & fluid resus
- Escharotomy is the surgical incision through burnt skin to release oedematous tissue & pressure, restoring circulation
Silver nitrate/Acticoat
- Very popular cream/dressing used in burns that are contaminated, infected, deep or full thickness, minor burns with large surface area
- Broad spectrum antibacterial activity by disrupting bacterial components (DNA) and metabolism, killing microorganisms
- Acticoat is lined with a soluble silver film that maintains silver ions in a wound for up to 5 days (kills bacteria & allows for less dressing changes)
- Can cause allergies and skin irritation
Complication - infection
- Common in wounds with coagulated proteins and microbial nutrients
- S&S: spreading erythema, warmth, tender, slough, deepening, purulence, discoloration, fever
Treatment: swab for culture, PO antibiotics that cover staph aureus & strep pyogenes, possibly surgical excision, topical AB (if not invasive infection), systemic AB if confirmed infection & sensitivities
Prevention: regular wound assessment (colour, odour, exudate), aseptic technique, debridement, antimicrobial dressings
Complication - Contractures
- Burn scar matures, thickens and tightens, preventing full range of movement
- Mediated by myofibroblasts that full wound edges together, however in excess this can cause contractures
Prevention
* Splits on the joint to keep it straight
* PT involvement to provide ROM exercises to keep limbs flexible
* Encourage early movement and independence
Vancomycin
Route: IV, PO
Class: glycopeptide AB
Mechanism: inhibits cell wall synthesis of gram+ bacteria including MRSA
Effect: eliminates systemic infection from the body, improves wound healing
Half-life: 6 hours
SE: abdominal pain, diarrhoea, dizziness, blurred vision, flushing, bloating
Oxycodone IR (oxynorm)
Route: PO
Class: opioid agonist
Mechanism: binds to opioid receptors (mu, but also k & d) which produces an analgesic and sedative effect
Effect: analgesia from moderate to severe pain
Half-life: 3h
SE: constipation, cramps, drowsiness, resp depression, euphoria, chills/sweats
