Our skin is the largest organ in the human body, making up 8% of our body mass.
Let’s take a quick look at the function and structure of skin before discussing burns:
🏗️ Structure of skin
Skin differs depending on the location in the body. There are different types of skin such as thin, hairy/hirsute, or glabrous skin (thick skin seen on the palms, soles, flexor surface of the fingers).
There are 3 layers to skin:
Epidermis
Most superficial layer made up of keratinocytes that undergo maturation.
Itself is made up of 5 layers:
- Stratum basale
- Stratum spinosum
- Stratum granulosum
- Stratum lucidum
- Stratum corneum
Other cells include melanocytes, Langerhans cells (APC dendritic cell), Merkel cells (mechanoreceptor cell).
It secretes glycolipids to prevent water evaporation through our skin and also to prevent water seeping into the tissues.
Hypodermis/subcutaneous tissue
Lies deep to the dermis. Its job is is to store adipose tissue and insulate deeper structures.
👏 Functions of the skin
The skin acts as a barrier between the environment and the body. It protects against microbial invasion, mechanical, chemical, osmotic, thermal and UV damage.
Other functions include:
- Vitamin D synthesis
- Thermoregulation
- Psychosexual communication
- Sensory organ for pain, touch, temperature etc.
Dermis
Lies deep to the epidermis and is connected through tight junctions. It has 2 layers, a papillary layer more superficially and a reticular layer that is deeper.
It contains multiple cells such as fibroblasts, mast cells, hair follicles, sebaceous glands, sweat glands (may be eccrine or apocrine [in axillary and genital regions]).
A burn is defined as an injury caused by exposure to heat, chemicals, electrical energy, radiation. It not only affects the skin, although this is most common, but also affects the airways, lungs, muscles, bones or internal organs.
A scald differs as this is an injury caused by hot liquids or steam.
Smoke inhalation causes bronchospasm, increased mucous production and increased airway perfusion. This increase in blood flow causes pulmonary oedema as there is transvascular fluid shifts. This leads to rapid respiratory distress.
These may result from exposure to acidic, alkaline or petroleum substances. Alkali burns tend to be more serious than acid burns as they lead to deeper damage with irreversible protein and tissue injury.
The mechanism for this is that acids cause tissue coagulation and collagen shrinking (coagulative necrosis) which acts as a barrier for further penetration. However, alkali substances cause hydrophilic and lipophilic degeneration (liquifactive) which breaks down cell membranes and allows further penetration into the cells.
They often appear less severe, although they cause very severe damage underneath the skin surface. This is because the electricity travels along the path of least resistance and the skin provides the most resistance (followed by bone) while nerves, muscle and blood have the least resistance.
Rhabdomyolysis occurs leading to myoglobin release and AKI consequentially.
There is great risk of cardiac damage if the path the electricity travels traverses the heart.
🔢 Classification
We can classify burns on the extent, complexity, depth of the burn.
Extent of burn
We can use Wallace’s rule of lines in adults:
- Head and neck - 9%
- Anterior portion of arms - 4.5% each (9% total)
- Posterior portion of arms - 4.5% each (9% total)
- Anterior portion of legs - 9% each (18% total)
- Posterior portion of legs - 9% each (18% total)
- Anterior thorax - 9%
- Posterior thorax - 9%
- Anterior abdomen - 9%
In children, a Lund and Browder chart is used.
Complexity of burn
We can classify them as non-complex or complex.
- Non-complex burns (minor burns)
A partial thickness burn affecting:
→ <15% of the total body surface area in adults
→ <10% of the total body surface area in children over 1 years old
→ <5% of the total body surface area in children under 1 years old
It also needs to affect a non-critical area
- Complex burns (major burns)
A complex burn is a burn that:
- Affects critical areas
- Affects >15% in adults, >10% in children, >5% in children under 1%.
- Is a chemical burn
- Is an electrical burn
Critical areas are face, hands, feet, perineum, genitals, burns crossing joints, or circumferential burns.
Depth of burn
We used to classify burns by degree (1st - 4th) but now the terms we use have changed (superficial epidermal burn → full thickness burn).
Old term | New term | Appearance |
1st degree | Superficial epidermal burn | Red, painful |
2nd degree superficial | Partial thickness (superficial dermal) burn | Pale pink, painful, blistered |
2nd degree deep | Partial thickness (deep dermal) burn | White ± non-blanching erythema, reduced sensation |
3rd degree | Full thickness burn (reaching subcutaneous layer) | White/black/brown, no pain, no blisters |
4th degree | Full thickness burn (reaching muscle and bone) |
🚨 Complications
Early complications
- Respiratory distress - due to smoke inhalation or if there is a circumferential chest burn.
- Poisoning - due to inhalation of noxious gases released by burning.
- Hypovolaemic shock - due to fluid loss.
- Hypothermia
- Wound infection & sepsis
- Toxic shock syndrome
- Arrhythmia
- Vascular problems
- AKI
- Limb loss
- Death
Late complications
- Wound infection & sepsis
- Chronic neuropathic pain
- Scarring
- Contractures
- Mental impact
- Sleep disorders
🧰 Management
The management depends on the complexity and type of burn sustained:
ABCDE assessment is necessary. It is also necessary to wear PPE to prevent any contamination.
🔥 Thermal burns
- ICE the burn (not literally):
- Irrigate the burn within the first 20 mins with cool water (not ice cold) for 20-30 mins. Ice cold water causes vasoconstriction which is not desirable.
- Clingfilm the burn.
- Elevate the burnt area to reduce risk of oedema.
Also offer analgesia.
Non-complex thermal burns can be managed in primary care while complex thermal burns can be referred to the ED.
⚡ Electrical burns
Low-voltage sources (such as domestic electrical supplies [220-240V]) should be switched off and the person should be removed from the electrical source with a non-conductive material. High-voltage sources (1000V) should not even be approached.
Immediate referral to ED is necessary.
⚗️ Chemical burns
Remove any of the chemical residue and irrigate with water for 1 hour.
Acid burns are coagulative while alkali burns are liquifactive. Therefore alkali burns are more serious concerns.
Immediate referral to ED is necessary.
💨 Inhalation burns
There are currently no guidelines to guide decision making for inhalation injuries but a couple of things need to occur:
- Rapid and safe extraction of the patient from the scene.
- Once clear of the fire (very important), high flow humidified oxygen should be given immediately. The high flow 100% oxygen reduces the half-life of carbon monoxide (CO) and all inhalation injuries should be presumed to have concomitant CO poisoning as this is responsible for most deaths.
- Thromboprophylaxis should also be provided.
- Fluids should be considered (based on urine output and haemodynamic parameters) but are not always needed and there is a risk of over-replacement which can lead to pulmonary oedema.
They usually heal within 2 weeks:
- Superficial epidermal burns
- Analgesia
- Emollients
- Superficial dermal burns
- Cleanse wound
- Leave blister intact
- Apply non-adherent dressing
- Avoid topical creams
- Review in 24 hours for infection and wound progression.
Adhere to the immediate first-aid as described above.
- IV fluids should be given. They are calculated with the Parkland formula:
- Fluid volume = TBSA of burn % x weight (kg) x 4
- The Modified Parkland formula is the same but multiplied by 3.
- Fluid volume = TBSA of burn % x weight (kg) x 3
- The first half is administered in the first 8 hours and the other half in the next 16 hours.
- Urinary catheter to be inserted
- Analgesia
- Transfer the patient to the complex burns unit
- Excision of burn & skin grafting may be needed.
For circumferential burns of a limb/torso:
- Escharotomy to remove the burnt tissue. This prevents compartment syndrome in limbs and improves ventilation of the torso.
Despite the risk of sepsis, prophylactic antibiotics has no supporting evidence in burn patients.
- Aged <5 or >60 years old
- Critical area burns
- Full thickness burns
- >10%TBSA in adults >16 years old
- >5% in children aged <16 years old
- Chemical, electrical and inhalation burns
- Suspected non-accidental injury in children
- Any complex burn