Jerome's Notes

Burns

temperatures >40°C cause skin burns

Aetiology

Depth

· Location

— Thick vs thin skin

· Temp @ location

· Duration of exposure

Type

1.       Thermal

2.       Electrical

Electrical flash burns: There is no conduction of current and so superficial burns

Contact burns due to ignition of clothing

Conductive burns due to passage of current from entry to exit point

The injury is determined by voltage, type of current and path of current.

The damage is the result of differential tissue resistance. Skin has low resistance and so relatively little damage. Underlying muscle, bone, nerve and vessels have much greater resistance and so damage.

· Areas of injury

— Nervous system

Immediate LOC, peripheral & spinal cord paralysis

Delayed Can take up to 3 yrs to evolve

Seizures, paralysis, headaches, depression, transverse myelitis, aphasia

— Bone

# 2° to tetanic contraction / falls

— Muscles & vessel

Muscle damage & necrosis

Rhabdomyolysis ± ATN

Compartment syndrome

Vessel thrombosis ® delayed necrosis (up to 10/7)

— Cardiopulmonary

Arrest Cardiac & respiratory (brain stem)

Arrythmia

Myocardial damage need 11-30,000 V

— Ocular

Cataract fromation

Management principles

Assess for other injuries caused by fall/LOC/tetanic muscle contraction.

· A – Airway management with cervical spine control

· B –

· C – monitoring and treatment of cardiac arrhythmia. More common in those who are acidotic or hyperkalaemic

· D – through neurological examination

· Extent of injury greater than suggested by BSA burn. Administer fluid to maintain UO >100ml/Hr

· Monitor ECG and electrolytes for hyperkalemia for arrythmia

· If a limb is swollen then check for fractures then prompt fasciotomy

· Necrotic tissue is debrided following conservative principles to save limb

· If evidence of myoglobinuria then: Alkalinize urine by adding 50mmol of Sodium · Barcarbonate to each 1L of fluid and maintain urine pH >7. Give mannitol 1g/Kg to maintain UO and act as a free-radical scavenger.

3.       Chemical

· Alkali or acid

· Acid

— more severe injury

— coagulation necrosis

— eschar formation

· Alkali

— more destructive

— liquefaction necrosis

— no eschar

Remove all clothing and shoes

Brush of all chemical powder before irrigation

After brushing off powder immediate and prolonged irrigation with water for 30 minutes with acid and 60 minutes with alkali

Phenolic acid must be irrigated with glycerol as it is not water soluble.

Physiology

· Microvascular and coagulation rxn in the surrounding tissue dermis

Increasing extend of injury

Larger injury can cause systematic response from this rxn due to loss of dermisàvasoactive mediatorsàinflammatory response or infection

--> Fluid loss from burn (partial>full)àodema

· Generalised oedema 2° capillary leak – increased microvascular permeability occurs within minutes to hours after injury

· Hypermetabolic status

Initial decrease in cardiac output and the metabolic rate output (ebb) in the first 12-36 hours from interstitial odema

Then doubling cardiac with ensuring circulatory hyperdynamism (flow). Accelerated gluconeogenesis, insulin resistance, and increased protein catabolism accompany this response.

— Full > partial

· Haemorrhage from other injuries

Mechanism of inhalational injury

· Heat damage to upper airway causing edema and obstruction

· CO poisoning

· Cyanide poisoning – cyanide gas released from burning of synthetic materials. Suspect whenever the CO level excess 10%.

· Inhalation of toxic smoke

Identification of inhalational injury

· Hoarseness of stridor

· Burns to face or oral mucosa

· Burns in an enclosed area

· Burns >50%

· Exposure to super-heated steam.

Vessel changes

· Full thickness

— Deep coagulation necrosis obliterates bv (? basal membrane)

· Partial thickness

— Hyperaemia & vasodilatation

· Cytokine mediated change in vessel permeability

— Systemic effects can ® SIRS

Zones

· Necrosis: Central coagulation of protein and cell death

· Surrounding stasis with decreased microvascular blood flow – tissue which is potentially dead depending on adequate perfusion, infection and desiccation.

· Peripheral hyperaemia

Evaluation

Extent

· Rule of nines – only second and third degree burns are included when determining the need and volume of fluid resuscitation.

— front and back of arm 9%

— front of leg 9%; back of leg 9%

— head front and back together 9%

— anterior torso 18%

— posterior torso including buttock 18%

— Perineum 1%

v In a child hand = 1%

Depth

Burn wounds deepen over 48-96 hours so a better idea of which areas need grafting comes with time.

The ability to visually determine a burn that will heal from dressing or not in the first day is poor (50% correct); the accuracy of clinical prediction improves to 90% on day 3-7 post burn.

· Superficial – epidermis only – first degree

— red, painful (like sunburn)

— Epidermis only

— will heal in 5-10 days without scarring

· Partial thickness of dermis (can be divided into superficial and deep partial thickness burns) – second degree

— blanch, painful, blistering, desiccation of skin occurs

—   Epidermis and some dermis – some epidermal skin appendages remain from which epidermis regenerates.

—   For superficial burns healing occurs quickly (2-3 weeks) with minimal scarring or pigmentation change; for deeper partial thickness burns healing is slower (3-4 weeks with hypertrophic scarring and unstable epidermis).

— Will declare themselves in a week.

— Depending on depth may need grafting

— Healing without grafting 2-6/52

· Full thickness – third degree

— white, insensitive, leathery texture, waxy

— Unless <2cm in diameter these burns require grafting for healing.

Initial Mx

A

· early intubation with burns to mouth, neck

· danger signs of

— soot @ back of mouth / round nose

— facial / neck swelling

— stridor

—   carbonaceous sputum

—   The classic physical signs have a poor predictive value in excluding or assuring the diagnosis of inhilational injury.

—   Brochoscopy is a reliable means of diagnosing inhilational injury: carbonaceous material, erythema, ulceration of mucosa and edema below the level of the true vocal cords suggest inhalational injury.

—   Bronchoscopy occasionally produces false negative results in the hypo-perfused and hypovolumaemic patient. Here ¹³³Xe gas inhalation scan may be useful.

—   Mild inhalational injury is treated with humidified oxygen-enriched air and chest physiotherapy.

—   Severe injury requires ET intubation and regular pulmonary toilet.

—   Patients at risk should be started on 100% O2, carboxyHB levels checked and flexible bronchoscopy performed. Inhalational adrenaline treatment can be given. An ET tube is threaded over the bronchoscope and the patient intubated if erythema, oedema or blackened sputum is found

B

· risk of LRT burns – injury to lower airway caused by chemical irritants associated with combustion and closed space burns.

· warning of pulmonary oedema

· Ix

— CXR

— ABG

— Carboxyhaemoglobin levels for fires

· CO poisoning

— Pa02 & Sa02 may be normal

— Metabolic acidosis

— Assume CO exposure in ptys with burns in confined spaces

— Clinical

Headache, N&V, mental disturbances, cherry red lips

— Check Carboxy Hb level

³ 10% 100% O2

³ 20% IPPV 100% O2

— t1/2 CO

250 min room air

60min 100% O2; 45 min with 100% O2 and PEEP and 25 min in hyperbaric chamber

C

· Will require IV fluids if >12-15% burns

· 2 large bore cannulae in upper limbs avoiding full thickness burns

· NGT

· U+Es, FBC, Xmatch

· 1L of plasmalyte stat if evidence of shock

— p>120 BP<100

— 20ml/kg in children

· catheterize for >15% burns

D

· Drugs

— IV narcotics titrated against pain

— Tetanus prn

E

· Escharotomy circumfrential burns of limbs or trunk

— may require division down to including deep fascia to prevent tourniquet
- sites:

· Excision of certain chemical burns

— phosporus, chromic acid

Admissions

· ³ 10% burn

· burns to face, neck, perineum, hands, feet

· significant smoke inhalation (do CO-Hb levels)

· pain requiring narcotics

· threat of Non-accidental injury or self harm

Post-resuscitation

Fluids/Electolytes

First 24 hours

· IV fluids & IDUC for burns >15%

· Parkland formula 4 ml x kg x % burn (resuscitation)

— give 1/2 of deficit + maintenance in first 8hrs (from time of burn)

— give 1/2 of deficit + maintenance in next 16hrs

Or Children 3ml x kg x % burn for the lst 24 hour

the same principle applied for administration

the 0.5ml x kg x % burn for 2^nd 24 hour resuscitation fluid + normal maintaince

· Fluid is Ringer’s lactate

· risk of hyperkalaemia

· adjust as per clinical progress

· Q4H biochemistry with burns > 20%

· risk of tubular blockage with haemoglobinuria/myoglobinuria

— maintain U/O @

0.5 – 1.0 ml/kg adults

1ml/kg in children

2.0 ml/kg neonates

— If UO ¯ then ­ rate do not bolus (risk of excessive tissue odema)

· 50ml of whole blood is required for each 1% BSA burn. Half in first four hours and remained in next 20 hours.

Second 24 hours

· Usually 5% albumin in normal saline is administered to aid correction of plasma volume deficit. This is required only with burns >30%BSA. This volume is infused at a constant rate over the second 24 hours. 5% Dextrose is administered to maintain urine output at 0.5-1ml/Kg/hr once the first 24 hours has elapsed.

· 30-50 % BSA: 0.3ml/kg/%BSA

· 50-70 % BSA 0.4ml/kg/%BSA

· >70 % BSA: 0.5ml/kg/%BSA

Respiration

· risk of ARDS

— Rx with ventilation and PEEP

— avoid sux (hyperkalaemia))

· ABG may show metabolic/respiratory acidosis

Dressings

Inital

· Initial wound care is a sterile sheet or surgical drape. Cling wrap can be used initially

Definitive wound care need not occur in the first 24 hours.

· Keep the environment to >90degrees F.

Escharotomy

· Circumfernetial full-thickness burns may impair the circulation of the underlying limb.

Oedema beneath the eschar impairs the circulation to underlying and distal tissues

· Circumferential truncal burns may impair chest wall movement and ventilation.

How do you assess the need for escharotomy in a circumferential burn?

· Repeated assessment in intervals of no less than one hour

· Progressive decrease of absence of pulsitile flow in the palmar arch and digital vessels with CW Doppler.

· Deep tissue pain, cyanosis, parasthesia, slow cap refill are hard to assess in the burnt limb

· The escharotomy is performed in OT without local or general anesthesia

· Incise first the mid-lateral aspect of the limb through the entire length of eschar.

· If pulsitile flow is not detected in 5 minutes then repeat on the mid-medial aspect of the limb.

· Incise just the eschar.

· Tuncal escharotomy: falling O2, rising CO2 or airways pressures (in the ventilated patient) and tachyponea and restlessness (in the spontaneously breathing patient) can all be indications of need for truncal escharotomy

· Bilateral mid-axillary incisions are performed and joined in the middle at the lower border of the costal margin. Transverse incisions at the upper sternal border and epigastrum can be added if the eschar extends on the abdomen.

Burn debridement

· Wound excision is required in deep partial thickness and full thickness burns

· This can be performed within 24 hours for small/moderate size burns (30%) but may be delayed for 4-10 days in the unstable frail or septic patient.

· Prompt burn wound excision and skin grafting reduces the length of hospital stay and period of rehabilitation

· Use a pneumatic dermatome to tangentially excise tissue to reach the deeper viable tissue.

· A: superficial partial thickness: Pass the pneumatic dermatome once to expose viable dermis with punctuate capillary bleeding

· B: Deep partial thickness: sequential passes of the dermatome are required to excise deeper burn wounds.

· C: Deeper burns can be excised with a scalpel down to the level of the deep fascia – a technique which reduces blood loss.

· Excise no more than 20% BSA in each theatre visit as this corresponds to circulating blood volume loss or 2 hours operating.

Blood transfusion is routinely required

· Wound coverage is generally best achieved with autologous SSG.

· SSG are harvested to a thickness of 0.008-.012 inches: the thinner the greater the take rate and the better the donor site recovery but the worse the recipient site cosmesis.

· Meshing at a ration of 1:1.5  to 1:4 is used. Mesh ratios greater than 1:4 required prolonged time for healing. The greater the mesh ratio the greater the take rate but the slower the healing.

· The excised wounds should be immediately covered with autologous skin if available

· If donor sites are insufficient then cadaver skin (human allograft), pig skin (procine xenograft) or biosynthetic products can be used (integra, transcyte or biobrane) can be used. Cultured autologous keratinocytes are being evaluated.

· The biological dressings prevent wound dessication, limit bacterial ingrowth, reduce evaporative water and heat losses, improve healing quality, reduce wound oedema, and promote wound regeneration.  

· These biological dressings provide wound coverage whilst donor site heals before donor site re-harvest can occur.

Definitive wound dressing

· Goals: aid healing and prevent wound infection which leads to sepsis.

· Patient is cleaned and showered. Residual damaged dermis and epidermis is removed and extent of burn is mapped with Lund and Browder chart.

· Superficial burns do not require dressing

· Some partial thickness and full-thickness burns to face and hands do not require dressings

· Typical dressing: Topical SSD (sulfa allergy, neutropenia, resistance of clostridia and certain gram negative bacteria), Adaptic, fluffed dry gauze (Velban) and elastic gauze Kerlix.

· Dressing changes should be performed when the dressing is soaked with excessive exudates or fluid.

· Other topical agents include sulfamylon (better penetration of eschar), silver-nitrate (Good antibacterial spectrum but requires continuous moistening and stains)

· Dressed areas should be monitored for signs of locally invasive infection (erythema or oedema of wound, black discolouration, separation of eschar, haemorrhagic discolouration of fat) and systemic infection (pyrexia, tachycardia and acidosis).

· Infecting organisms are initially gram positive (Staph or step) and then gram negative (kelsiella, proteus, coliforms, pseudomonas).

· Daily swabs can be taken from second degree burns. However this does not reliably differentiate infection from colonization.

· Biopsy from burn if colony count >10⁵ bacteria/g tissue indicates invasive wound infection.

· Biopsy from tissue adjacent to burn is most reliable means of differentiating infection from colonization. If viable bacterial are found in adjacent viable tissue systemic antibiotic treatment is used often combined with sub-eschar antibiotic c lysis with a 20G spinal needle. The infected eschar is then excised and should be covered with an allograft or biological dressing to avoid wasting autograft skin on infected wound.

Anti-biotics: Vancomycin for early infections; Cipro or Gentamicin for infections after 7 days.

Antibiotics

· Tet tox

· systemic prophylaxis breeds resistance

· Culture every 48hrs

· if bug cultured then treat for only 4-5 days to prevent superinfection

Nutrition

· >20% burns consider feeding

Curreri formula: {25kCal × weight (Kg)} + {40kCal × % BSA burn}

Protein requirement is increased to 3g protein/Kg/Day

Metabolic requirements are increased in proportion to the size of burn, infection and environmental temperature.

Calorific requirements can be minimized by controlling infection, avoiding hypothermia and pain.

—   enteral preferable within 6hrs – most often naso-duodenal route.

—   If enteral feeding is not possible due to ileus or gastroparesis, Parenteral supplementation.

Recovery

· Wound contracture - physio

· Body image

· Psychological/Emotional support - support group

Risk of death from burn injury

· Three risk factors can be identified which weigh equally on risk of death:

l   %BSA >40%

l   age >60 years

l   inhalational injury

As the presence of these risk factors increases so the mortality increases:

0 risk factors – 0.3%;

1 risk factor 3%;

2 risk factors 33%;

3 risk factors 90%.

· If age + % BSA exceeds 100 then mortality will be 50%.