Burns can be a very challenging presentation to manage, although the spectrum of injury can be very variable. These notes will focus more on the critically ill/severely burned patient. Much of them will also focus on the management of thermal and flame type burns, which are more common, with more specific discussion of less common burns e.g. chemical, elsewhere.
A burn is defined as “an injury to tissues occurring from exposure to heat, cold, chemicals, friction or radiation”.
Burns may occur from several different sources:
The tissue injury that occurs from the burn leads to an inflammatory response, which can be significant in large burns with lots of cellular damage. This is similar to other SIRS pathology, with increased production of a number of pro-inflammatory mediators with their well recognised systemic effects:
Increased vascular permeability
Initial decrease in cardiac output and increase in SVR
Hypermetabolic state (up to 2-3 times baseline) with catabolic state
There are a number of different adverse effects arising from the subsequent loss of skin function that occurs from significant burns.
Increased insensible fluid losses
Loss of protective dermal barrier function
Inhalational injury is an important factor in major burns and is covered in more detail here.
A lot of important information can be gained from the presentation. This may radically alter a management strategy. Key things that can be obtained include:
Other trauma - the burn may be part of a larger trauma mechanism
The type of burn - these may be managed very differently
Risk factors for specific additional features - e.g. risk of inhalational injury.
Mechanism of injury As much detail about this should be obtained:
Mechanism of trauma
As part of other trauma? e.g. RTC
Potential injuries from escaping fire? e.g. jumping out of window
Location of trauma
Inside house vs outside?
Nature of burning material? - toxicity risk
Medical Background This may need to be obtained early.
Sources There may be a need to obtain history from sources other than the patient about the nature of the events. Consider the paramedics, fire crews, relatives, coworkers (e.g. if industrial).
Prior to assessment, it is important to remember that personal protection may be more relevant in these cases than in some other presentation. Chemical burns are particularly relevant from this perspective.
In general, assessment will be guided by the severity of the burn. Minor, peripheral burns may be reviewed on a history, examination, investigation pattern. More serious injuries are best approached using that as for a major trauma i.e. an A to E assessment, preferably in parallel as part of a team.
Airway and Cervical spine protection & Breathing It is important to remember that burns may be in addition to, and even masking, other traumatic injuries. Cervical spine precautions are therefore essential to consider. High flow oxygen should be administered to almost all of these patients initial, as there is a significant risk of hypoxia in this cohort.
The assessment of inhalational injuries is covered in more detail here. Consideration will need to be given to:
Inhalational thermal injury - usually upper airway
Inhalational non-thermal injury - usually lower airway
Systemic toxicity e.g. CO, cyanide
Additional features of respiratory assessment should consider:
Encircling deep thoracic burns - may restrict ventilation
Blast injuries - may result in pneumothoraces
Circulation This should involve a standard assessment of CVS stability. Large bore IV access should be obtained - this may be more difficult if there have been significant burns to usual cannulation sites. Ideally IV access should be through intact skin (potentially not always feasible initially).
Hypovolaemia from burns does not occur very early (i.e. during the initial presentation). In cases of early CVS compromise, consideration should primarily be given to other trauma as the cause e.g. haemorrhage.
Disability This should be carefully assessed. An altered conscious level can point to important differentials e.g. traumatic brain injury, systemic poisoning. A gross neurological exam may also help in this regard. There may be overlap with CNS acting drugs and the cause of the fire e.g. alcohol.
Pain should be effectively and promptly treated.
Exposure This is a crucial step. Full assessment of the extent of cutaneous burn should be made at this time (see below) - this includes the back, which may require log rolling. The patients clothes will need to be fully removed, taking care as some adhesion to skin may occur with significant burns (in this case cut around the adherent parts). Jewellery (rings, watches) should be removed early, as swelling may lead to problems.
Patients must be kept warm, as temperature homeostasis is severely compromised in major burns, and treatment (cooling the burns) can rapidly drop core temperatures.
Secondary Survey After the initial primary survey, a careful secondary survey is essential to identify other potentially important features.
This has two main components:
Extent of burn - described by total body surface area (TBSA)
Depth of burn
Extent of Burn There are several methods for estimating the TBSA that has been burned:
The rule of nines
The 1% rule
Mersey burns app
Lund and Browder chart
Serial halving method
The rule of nines is a relatively simple method that can allow decent estimations of TBSA in the case of relatively large burns. It works by allocating 9% (or factors of) patches of skin to different parts of the body:
Head and neck - 9%
Upper limb - 9% each
Lower limb - 18% each
Front of trunk - 18%
Back of trunk - 18%
Genitalia - 1%
Using these as guides, estimates can be made when there isn’t complete burn of an area e.g. half an upper limb is burned, so the TBSA is about 4.5%. Due to the different proportions in children, different values are used. Similar problems may arise from the different body shapes of adults e.g. obese patients.
The 1% rule is useful for assessing smaller areas of burn. It states that the palmar surface of the patient’s hand, including the digits with the fingers spread apart, is equivalent to 1% of the TBSA. This is less accurate in patients with a higher BMI.
The Mersey Burns app is a very useful tool for calculating the TBSA (as well as other aspects of burns management). https://merseyburns.com/ The app allows the area that is burnt to be coloured in on a chart, and will then calculate the TBSA.
Challenges with ascertaining the extent of the burn may also include the fact that some features of the burn may be dynamic. Blisters may develop, or erythema may improve, changing the proportion of skin that should be included in the TBSA calculation.
Depth of Burn The severity of the burn, in relation to its depth, is another essential part of the assessment. Burns can be described as:
Partial - superficial and deep
Superficial burns only involve the epidermis. It is essentially equivalent to sunburn.
Partial burns are divided into superficial partial, which involve the epidermis and the upper layers of the dermis, or superficial deep, which extend into the deeper layers of the dermis.
Deep burns include all layers of the dermis and may include the underlying tissue. These are classically described as painless (because of the destruction of skin nociceptors) but pain may still be present in nearby tissue that doesn’t have deep burns.
First Aid Whilst not necessarily the first thing that comes to mind in critical care, this is an essential component of the management of burns. The priority is cooling of the burn. This stops further thermal injury occurring, reduces the developing inflammatory response, and can provide symptomatic relief. This can have benefits up to 2 hours after the initial injury.
Key steps are:
Remove any burning material
Cool running water if possible
Cool compresses if difficult e.g. truncal burns
Cool for 10-20 minutes minimum
Ideally the water should be clean and cool rather than cold. Ice should be avoided as it can cause further thermal injury.
Fluid Therapy This is a key component of burns management, as patients will experience significant fluid shifts due to:
Loss of skin integrity
Third space shifts due to inflammatory process
Whilst there will initially be compensation, several hours after the burn insult these losses will start to become significant and lead to increasing compromise. In general, the patients who will be unable to compensate with oral fluids are:
Adult patients with TBSA burns > 15%
Children with TBSA burns > 10%
This can be difficult to assess. The most common approach is to calculate the fluid requirements. The most common formula is the Parkland Formula: Total fluid requirement for 24h after burn = 4ml x weight x %TBSA burn.
Half of this is given over the first 8 hours. The fluid that should be used is a balanced crystalloid e.g Hartmann’s solution. Small children e.g. under 30kg, may need larger volumes due to their higher surface area compared to body mass.
Tetanus It is important to consider tetanus status in patients with significant burns. Prophylaxis may be required in some cases.
Secondary Infection Patients will be at increased risk of secondary bacterial infections. Special care needs to be taken with further hospital care to minimise these risks. This may include:
Strict aseptic technique for invasive procedures
Routine line changes
Critical Care All the other tenets of good critical care practice continue to be essential in these patients to avoid complications.
In adults, burns relating to fire are the most common cause. In children, scalding injuries are more prevalent. Around 140,000 new burn injuries present to A&E each year in England and Wales.
Risk factors for mortality include:
Increasing age (notably > 50 years)
Increasing TBSA burn % (notably > 40%)
Depth of burn
Delayed resuscitation (> 2 hours post insult)
Overall inpatient mortality for burns is about 14%.
These are very varied, and can arise from the burn pathology itself or as a complication of subsequent treatment.