Derm - Burns

Question 1

Describe the pathophysiology of major burns.

Answer 1

Can be divided into 3 pathological processes which can exacerbate each other:
1. SIRS - activation of inflammation, vascular permeability and oedema.
2. Inhalation lung injury - ARDS, airway obstruction.
3. Hypermetabolic state - increased protein catabolism, increased gluconeogenesis, decreased proteins synthesis - leading to immune suppression, poor wound healing, infection risk.

Question 2

How is burn severity estimated?

Answer 2

1. Burn area (%TBSA):
   - Lund-Browder charts
   - Rule of nines
   - patient palms (=1%) area.
2. Burn depth:
   - Superficial - involves epidermis only, red and painful but no blistering.
   - Partial-thinkness - painful and with blistering
   - Full-thickness - all skin layers involved, painless, white

Question 3

What are the management priorities in a patient presenting with major burns?

Answer 3

Resusitation using ATLS A-E approach:
Airway and ventilatory management with c-spine control:
- facial burns
- carbonaceous sputum
- singed nasal or facial hair
- oropharyngeal oedema
- stridor
- hoarseness
- low GCS
- neck burns
- ventilatory failure
- uncut ETT >7.5
- Lung protective ventilation
Circulation
- establish wide bore IV access and commence fluid resuscitation as per Parklands formula (4ml/kg x %TSBA burns)/24 hrs - half given in the first 8 hrs.
Disability:- Analgesia
Exposure:
- avoid hypothermia
- consider early surgical management for circumferential burns
- establish history of circumstances (enclosed, blast, chemicals, CPR etc).

Question 4

What is inhalation injury and how is it managed?

Answer 4

Inhalation injury is the exposure to smoke for a prolonged period of time.It is particularly associated with entrapment in an enclosed space and carries a significant increased mortality.It has two main mechanisms of injury:
1. Thermal injury - causing swelling and oedema to upper airway
2. Chemical irritation - acid or alkaline compounds released from burning material cause epithelial and capillary damage. - causes severe tracheobronchitis, loss of mucociliary clearance and loss of surfactant.- ARDS picture
Managed with:- early bronchoscopy and BAL- LPV +/- ECMO

Question 5

What is burn shock?

Answer 5

A combination of hypovolaemia, distributive and cariogenic shock seen in a major burn, which is refractory to fluid resuscitation.

Question 6

When should infection be treated in major burns patients?

Answer 6

Difficult to differentiate infection from SIRS and hypermetabolism.
American Burn Association:
Documented infection and 3 from:
- temp <36.5 or > 39
- Need for minute volume >12L/min
- HR >110
- Glucose >12.8 in non-diabetic
- Intolerance of enteral feed for >24hrs
- Platelet count <100

Question 7

How does carbon monoxide poisoning present and what is the management?

Answer 7

Carbon monoxide has much higher affinity for haemoglobin than oxygen. This cause a tissue and cellular hypoxia by:
- shifting oxygen-dissociation curve to the left
- inhibiting mitochondrial cytochrome oxidase.

Presents with:
- Neurological features: Headaches, confusion, coma, seizures
- GI features: Nausea and vomiting
- cherry
-red skin

Investigate by checking HbCO on co-oximetry:
- normal is <1% (smokers <5%)

Management is:
- 100% O2
- IPPV if HbCO >25%
- hyperbaric (3atm) oxygen therapy (if HbCO >40%, pregnant and HbCO >15% or coma)

Question 8

How does cyanide poisoning present and what is the management?

Answer 8

Cyanide inhibits mitochondrial cytochrome oxidase causing cellular hypoxia and forcing anaerobic metabolism.

Presents with:
- Neurology: Dizziness, psychomotor agitation, loss of consciousness
- Respiratory: breathlessness

Investigations:
- very high ScvO2
- lactic acidosis
- cyanide levels (take >3hrs to come back)

Management:
- Supportive therapy inc 100% O2 or IPPV
- chelators: tydroxycobalamin, dicobalte edetate, sodium thiosulphate

Question 9

What are the criteria for referral to a burns centre?

Answer 9

1. Age <5 or >60
2. Comorbidities affecting healing
3. Site: face, hands, feet, perineum, neck, circumferential or full thickness burns
4. Inhalation injury
5. Mechanism: chemical, ionising radiation, high pressure steam, electrical injury, cold injury, hydrofluoric acid injury, NAI

Question 10

What are the potential complications of a major burns patient?

Answer 10

1. Respiratory - airway occlusion, ARDS
2. CVS - arrhythmias, cardiac failure, vasoplegia
3. Neurological - pain, compartment syndrome
4. Renal - AKI, abdominal compartment syndrome, rhabdo
5. GI - hypermetabolism, stress ulcers
6. Haematological - VTE
7. Infective - soft tissue infection, pneumonia, line-related, MDR
8. MSK - contracture, amputation
9. Iatrogenic - over-resuscitation oedema, VAP.
10. Psychological impact.

Question 11

What is severe burn?

Answer 11

> 20% TBSA
Associated inhalation injury
Associated trauma
Chemical burn
High voltage electrical burn

Question 12

How can we prognosticate in burns patients?

Answer 12

Revised baux Score
Age + TBSA (+17 if inhalation)