KEY NOTES CHAPTER 8: BURNS - Epidemiology, Diagnosis, Inhalation Injury, Resuscitation, Nutrition, Sepsis. Flashcards
How do you classify burns?
Aetiology
- Thermal
- Chemical
- Electrical
- Cold Injury
- Radiation
Depth
- Superficial
- SPT
- DD
- FT
Resus (>15% adult, 10% child)
What is the incidence of burn injuries in UK?
250,000 injuries 300 deaths 50% TBSA - 10% mortality (50% 25yrs ago) 80-90% TBSA - <50% mortality (90% 10yrs ago) Improvements attributable to: - resuscitation. - surgical techniques. - sepsis management. - nutritional and metabolic support.
Thermal burns aetiology
scalds - hot liquids or gases
contact
flame
flash
Factors affecting survival in burns
TBSA Depth Age Inhalation injury Co-existing polytrauma Co-morbidities
What are the systemic effects of burn injury?
- with >25-30% TBSA, local inflammatory mediators (TNF, IL’s, interferon) overspill into systemic circulation.
- early excision and closure limits systemic inflammation.
Organ systems affected include - hypovolaemia myocardial depression - pulmonary oedema - renal impairment - hepatic dysfunction - catabolism - immunosuppression - loss of protective gut function - psychological effects
What are the different methods of estimating TBSA?
hand ~ 0.8% TBSA
Wallace’s rule of 9’s
Lund and Browder charts
Escharotomy
DD and FT burns are inelastic and can worsen constriction with fluid resuscitation
Escharotomy begin and end in unburnt/SPT skin
Limbs: mid-axial line
Chest: mid-axillary lines, chevron incision parallel to costal margin
Inhalation injury history
confined space unconscious in fire hoarse weak voice brassy cough restlessness SOB
Inhalation injury signs
soot in mouth and nose singed facial and nasal hairs deep burns for face, neck, upper body carbonaceous sputum swollen upper airway stridor, dyspnoea, hypoxia, pulmonary oedema
Inhalation injury investigations
CXR
ABG
COHb
Fibre-optic bronchoscopy - soot below vocal cords, hyperaemia, mucosal oedema and ulceration.
How do you classify inhalation injuries?
Supraglottic - caused by heat.
Subglottic - caused by products of combustion.
What occurs in subglottic inhalation injuries?
Bronchospasm, inflammation, increased secretions
- leading to atelectasis, ARDS, pneumonia
- VP mismatch
- decreased lung compliance
- increased airways resistance
How is respiratory failure treated?
humidified O2 nebulisers - heparin (prevent cast formation) - salbutamol - NAC (mucolytic) chest physio non-invasive ventilation with PEEP intubation, ventilation and bronchial lavage with dilute sodium bicarb
What is the treatment for CO poisoning?
100% O2, non-rebreathing mask (1/2 life 40mins, 250mins if breathing room air).
>25-30% - should intubate.
persistent metabolic acidosis - consider cyanide poisoning.
What are the benefits of tracheostomy?
Easier for toileting and lavage Improved weaning by reducing - dead space - airway resistance - work of breathing - sedation requirements
What are the complications of tracheostomy?
Bleeding Accidental decannulation Swallowing dysfunction Tracheal ulceration and granulation tissue T-O fistula Tracheal stenosis Tracheomalacia
What are the complications of inhalation injury?
Complications of mechanical ventilation: barotrauma and pneumothorax. Can be avoided by - pressure controlled ventilation - high ventilation rate - small tidal volumes - inverse ratio ventilation - physiological PEEP - lower target O2 sats of 92% - permissive hypercapnia and respiratory acidosis
Longterm
- ARDS
- MODS (multi-organ dysfunction syndrome)
- fibrosis ->emphysema, bronchiectasis
What are the goals of fluid resuscitation?
- Restore circulating volume.
- Preserve tissue perfusion.
- Avoid ischaemic extension of burn wound.
Parkland formula
4ml/kg/TBSA in 1st 24hrs (50% in 1st 8hrs).
Hartmanns solution contains Na, Cl, lactate, K, Ca.
What does overuse of crystalloid cause and what crystalloid sparing strategies are there?
Burns oedema drives burns shock, increased total body sodium and risk of abdominal compartment syndrome.
Muir and Barclay formula - resus with HAS
0.5ml/kg/% burn per time period.
3x 4hrs, 2x 6hrs, 1x 12hrs.
When may more resuscitation fluid be required?
- Paediatric burns
- Delayed resus
- Large burns
- Deep burns
- Inhalation injury
- Co-existing polytrauma
- Electrical burns, myoglobinuria
- Petrol burns
What end-points may be measured to determine adequacy of fluid resuscitation?
- Urine output (0.5-1ml/kg/hr adults, 1-1.5 children)
- PR, BP, CRT, RR.
- Core-peripheral temperature gradient.
- Urine osmolality.
- ABG - lactate and base excess.
- Tranoesophageal doppler to identify patients for inotropes/vasopressors (noradrenaline and dobutamine - but may worsen hypoperfusion and cause extension of burns).
What factors need to be considered for paediatric fluid resuscitation?
They have different TBSA proportions and reduced physiological reserves.
Maintenance fluids is required (per 24hrs):
- 100ml/kg for 1st 10kg,
- 50ml/kg for 2nd 10kg,
- 20ml /kg for remainder of body weight.
What are the complications of under-resuscitation?
Hypovolaemia. Shock. Renal failure. Ischaemia-reperfusion injury. MODS. Deepening of burn wounds.
