Thread: Burns

Burns

Pathophysiology

* Burn = Coagulative destruction of the skin or mucous membrane
* Caused by heat, chemical or irradiation
* Thermal damage occurs above 48 ºC
* Extent of necrosis is related to temperature and duration of contact
* Burns can result in:
o Increased capillary permeability and fluid loss
o Hypovolaemia and shock
o Increased plasma viscosity and microthrombosis formation
o Haemoglobinuria and renal damage
o Increased metabolic rate and energy metabolism

Assessment

* Initial assessment should be by ATLS principles
* Good early management is required to prevent morbidity or mortality

Airway

* Look for signs of inhalation injury
* Facial burns, soot in nostrils or sputum

Breathing

* Be aware of carbon monoxide poisoning
* Patient may appear 'pink' with a normal pulse oximeter reading

Circulation

* The fluid loss from a burn is significant
* It can result in hypovolaemic shock and acute renal failure

Assessment of extent

Body surface area (BSA) involved can be estimated from

* Lund & Browder chart
* Wallace rule of nine

Area % BSA
Head 9
Each upper limb 9
Each lower limb 18
Front of trunk 18
Back of trunk 18
Perineum 1

* Palm of hand approximates to 1% BSA

Burn depth

* Ability of skin to repair depends on depth of burn
* Burns can be classified as:
o Superficial burns
o Partial thickness burns
o Full-thickness burns

Superficial burns

* Needs to be differentiated from erythema
* Epidermis and papillae only are involved
* Results in red serum0filled blisters
* Skin blanches on pressure
* Burn is painful and sensitive
* Healing occurs in 10 days with no scarring

Partial-thickness burns

* Epidermis is lost with varying degrees of dermis
* Burn is usually coloured pink and white
* May or may not blanche on pressure
* Variable degrees of reduced sensation may be present
* Epithelial cells are present in hair follicles and sweat glands
* Results in regeneration and spread
* Healing occurs in 14 days
* Some depigmentation of scar may occur
* May require skin grafting

Full-thickness burns

* Both epidermis and dermis are destroyed
* Burn appears white and does not blanche
* Sensation is absent
* Without grafting healing occurs from edge of wound

Fluid replacement

To assess fluid requirement need to identify

* Time of injury
* Patient weight
* Percent BSA involved

Intravenous fluid replacement needed for burns

* >10% BSA in child
* >15% BSA in adult

Fluid replacement formulae
Muir & Barclay formula

* = weight (Kg) x BSA / 2 per period
* Provide volume requirement in colloid to be given in first 4 hours
* This volume should be repeated
o Every 4 hours for the first 12 hours
o Every 6 hours between 12 and 24 hours
o Every 12 hours between 24 and 36 hours

ATLS formula

* = weight (kg) x %BSA x (2-4)
* Gives total volume (in ml) to be infused in first 24 hours

Criteria for referral to burns unit

* > 10% BSA in child
* > 15% BSA in adult
* Inhalation injuries
* Burns involving the airway
* Electrical burns
* Chemical burns
* Special areas - eyes, face, hands

Escharotomy

* Deep circumferential burns of torso can impair respiration
* In a limb can reduce distal vasculature
* In both situations escharotomies should be considered
* No anaesthetic is required
* Burn should be incised into subcutaneous fat
* Release of underlying soft tissue should be ensured
* On chest should be performed bilaterally in anterior axillary line
* Bleeding may be significant and transfusion may be required

Special situations
Respiratory burns

* Smoke inhalations should be suspected if:
o Explosion in enclosed environment
o Flame burns to the face
o Soot in mouth or nostrils
o Hoarseness or stridor
* Intubation may be required
* Blood carboxyhaemoglobin levels can give indication of extent of lung injury

Electrical burns

* Most electrical burns are flash burns and are superficial
* Do not occur by electrical conduction
* Flash from an electrical burn can reach 4000 ºC
* Low-tension burns are usually small but full thickness
* High-tension burns usually have an entry and exit wound
* Current passes along path of least resistance (e.g. blood vessels, fascia, muscle)
* Extent of tissue destruction can often be underestimated
* High-tension burns can be associated with cardiac arrhythmias
* Myonecrosis and myoglobinuria can also occur

Chemical burns

* Commonest acids involved are hydrochloric, hydrofluoric and sulphuric
* Acid burns may penetrate deeply down to bone
* First aid treatment involves liberal irrigation with running water
* Calcium gluconate may be useful in hydrofluoric acid burns
* Commonest alkalis are sodium hydroxide and cement
* Again can cause deep-dermal or full-thickness burns

It's nicely given in LB.
But much lengthy.
anyone have better notes?

good post man simple n eay