Burns and ARDS Flashcards
How to calculate the surface area of a burn?
Wallace rule of nines
Face and neck anterior - 4.5%
Head and neck posterior - 4.5%
Thorax anterior - 9%
Thorax posterior - 9%
Abdomen anterior - 9%
Abdomen posterior - 9%
whole arm - 9%
anterior leg - 9%
posterior leg - 9%
groin - 1%
Calculating burn surface area in children
In children, because of the relatively larger head and smaller legs, the wallace rule of 9 underestimates the TBSA burned if applied directly without adjustment.
Head of children = 18%, legs 14% adujucted with age.
Lund Browder chart is more accurate, age adjusted.
Management of a Burn victim
ATLS approach
A - airway: look for signs of airway burns and inhalation injury as this may cause airway oedema. If this were the case I woud consider intubation.
B - Breathing: Ensure adequate ventilation, tracheal or pulmonary burns can affect gas exchange. Full thickness chest wall burns can impair chest expansion for which an escharotomy would need to be considered
C - 2 large bore cannulae (reliable venous access) inserted in the ACF and fluid resus started for all adults with TBA% >15% or children >10%. Amount of fluid required over 24hours calculated using parkland formula, 50% of the volume given in first 8 hours sicne the time of injury. Aiming for a urine output of >0.5ml/kg/hour, increasing rate of fluid if needed to achieve this. Catheterise for monitoring.
D - ensure thermoregulation, check glucose, AVPU
E - expose to ensure no further injuries and all source of burn has been removed.
Wy are colloids not given in burns?
in the first 24hours after a burn, there is increased capillary permeability. Therefore colloids can pass to the extravascular space, increasing the oncotic pressure and encourage paradoxical third-spacing
How would you assess the adequacy of fluid therapy
Clinical parameters
- urine output
- CRT
- peripheral warmth
- central VP and fluid response
- core temperature
- haematocrit
Complications of burns?
Burns shock - hypovolaemia due to plasma loss. Hypotension, tachycardia, increased sVR.
sepsis
ARDS
Renal failure (myoglobinaemia)
Constricting circumferential burns - limb iscahemia, ventilatory problems
Electrolyte disturbance - hypo/hypernatraemia, hyperkalaemia, hypocalcaemia
coagulopathy - DIC and hypothermia
Haemolysis
Key differences of management of electrical burns
High veolcity burns are often associated with deep tissue injury and muscle damage even if skin appears ok. There is therefore a higher risk of rhabdomyolysis and AKI.
Would calculate fluid requirement using the parkland formula. But aim for 1ml/kg/hour urine output (higher) to prevent renal damage from myoglobinuria.
Montior CK level
Consider alkalinsation of urine with bicarbonate
If established rhabdomyolysis and shock despite fluid resus, consider mannitol as an osmotic diuretic to protect kidneys.
What type of fluid are you giving a burns patient
Hartmann’s solution
Children are at risk of hypoglycaemia so often dextrose runs alongside
monitor for electrolyte abnomalities, especially hyperkalaemia.
Superficial burn appearance, involvement and healing
Appearance:
Red, dry skin.
No blisters.
Painful (due to inflammation, the dermis is intact).
Erythema with blanching (capillary refill normal).
Involvement: Only the epidermis (outer skin layer).
Healing: Typically heals in 3–5 days with no scarring
(mild sunburn is a classic example)
Superficial Partial Thickness burn Appearance, involvement and healing
Appearance:
Moist, pink to red, weeping surface.
Blisters or intact blistered skin.
Painful (due to involvement of the dermis).
Sensory: Centrally painful but outer areas may still be sensitive due to nerve involvement.
Capillary refill is still good (indicating some blood supply is intact).
Involvement: Affects epidermis and part of the dermis.
Healing: Can heal in 7–21 days, rarely scars, but may have some pigmentation changes.
Deep Partial Thickness Burns appearance, involvement, healing
Appearance:
Mottled red, white, or pale.
Texture: May feel waxy, skin may look dry.
Blisters may be thick or ruptured.
Blanching: Reduced or absent (blood flow is compromised in deeper dermis).
Sensory: Insensate or reduced sensation because deeper nerve endings are damaged.
Involvement: Affects epidermis and deep dermis (including sweat glands, hair follicles).
Healing: May take 21+ days, scarring is common, potential for contracture or abnormal healing.
Full Thickness Burn appearance, involvement and healing
Appearance:
White, charred, leathery, or dark brown/black.
Dry, cracked, and hard.
No blisters because the dermis is completely destroyed.
Sensory: Completely insensate — no response to touch or pain because the nerve endings are destroyed.
Involvement: Affects the epidermis, dermis, and may involve subcutaneous tissue, muscle, and bone.
Healing: Does not heal spontaneously; requires grafting or surgical intervention.
Fourth degree burn
Appearance:
Charred appearance, blackened tissue.
Eschar (thick leathery covering).
Involves deep tissue structures, possibly bone or muscle.
Involvement: Full-thickness destruction extending through the skin layers into muscle and/or bone.
Healing: Requires surgical intervention (e.g., amputation, grafting, or debridement).
Sensory: Completely insensate
How to assess burn depth in clinical practise
Clinical Appearance:
The classic descriptors of red, white, mottled, or leathery will guide you, but don’t rely solely on appearance.
Blister Formation:
Blisters tend to appear in partial-thickness burns, and their size and appearance can tell you whether it’s superficial or deep.
Large, thick, or ruptured blisters suggest a deep partial-thickness burn.
Pain Response:
Pain: Burns that involve the epidermis or superficial dermis will be painful.
Insensate: Full-thickness burns are insensate because nerve endings are destroyed.
Capillary Refill (Blanching):
Blanching indicates good blood flow, suggesting a more superficial burn.
If blanching is absent (in deeper burns), it suggests compromised blood flow, as seen in deep partial-thickness or full-thickness burns.
Touch and Texture:
Waxy, leathery, or hard texture: Typical for full-thickness burns.
Moist, pink, or red: Partial-thickness.
Use of Tools:
Laser Doppler or thermal imaging (in specialized centers) may be used to help assess burn depth in uncertain cases.
Burn depths summary
Superficial - arythema, no blisters, painful
Superficial partial thickness - blisters, painful, normal CRT
Deep partial thickness - thick or ruptures blisters, dry, waxy, reduced pain sensation
Full thickness - white, leathery, insensate
Definitiona dn characterisation of ARDS
diffuse alveolar damage and lung capillary endothelial injury. causes acute respiratory failure.
- hypoxaemia
- descreased lung compliance
- diffuse pulmonary infiltrates on CXR
- normal pulmonary artery wedge pressure (<18mmHg)
- Pao2/fi02 <26.6
what is Pa02
amount of oxygen dissolved in the blood reflects how well the lungs are delivering oxygen to the tissues
normal = 80-100 mmHg which is 11kPa
PaO2/FiO2
ratio of the partial pressure of arterial oxygen to fraction of inspired oxygen. determine the degree of problems with oxygen transfer in the lungs by comparing the oxygen level in the blood with what is breathed
Pathophysiology of ARDS
two phases
acute:
- widespread destruction of capillary endothelium, extravasation of protein rich fluid, interstitial oedema.
- release of cytokines and neutrophils (pro-inflamamtory cytokines are IL-1, 6 and TNF alpha)
- damage of alveolar basement membrane meaning fluid seeps inot the lungs casuing a v/q mismatch
chronic
- fibroplroliferation and organisation of lung tssue
- if the ARDS dosesnt reolve this will result in disordered collagen and extensive lung scarrung
conditions associated with ARDS
more than 50% of cases due to:
sepsis
diffuse pulmonary infections
gastric aspiration
mechanical trauma (head injury)
otherwise:
pulmonar contuson
near-drowning
fat embolism
burns
ionising radiation
hypersensitivity
inhalation injury
TRALI
DIC
pancreatitis
cardiopulonary bypass
what is the berlin cirteria
categorises ARDS into mild moderate and severe based on Pa02/Fio2 ratio and gives an associated mortality score 27,32,45% respectuvely
Management of ARDS
Patients should be managed on ITU.
Ventilation, steroid therapy, sepsis management, fluid management and other supportive care needs to be considered.
Respiratory support:
PEEP to prevent premature aveolar closure
prone positioning has been shown to be beneficial
Steorids:
low dose steroid theraoy is associated with improve morbidity and mortality
sepsis: treat according to cultures or with empirical abx if no source found
fluid:
ensure adequate fluid replacement. take care not to overload. monitor BP and UO. In ITU can use a swan ganz catheter to monitor PCWP.
consider inotropes such as dobutamine if circulatory failure despite hydration.
if there is overload consider IV furosemide
Supportive cares:
nutrition, ideally enterally
peptic ulcer prevention
VTE prevention
long-term sequelae of ARDS
impaired gas-exchage - impaired perfusion. V/Q mismatch
pulmonary hypettension
reduced lung compliance
ARDSNet protocol
The ARDSNet protocol is a lung-protective ventilation strategy that uses low tidal volumes (6 mL/kg of IBW), limited plateau pressures (<30 cm H2O), appropriate PEEP, and permissive hypercapnia to minimize ventilator-induced lung injury while ensuring sufficient oxygenation and ventilation.
This protocol is foundational in the ICU management of ARDS and is associated with improved outcomes
