title: Burns tags: #burns #FFICM #trauma notebook: ð-FFICM

source: [[eLfH]] category: [[trauma]]

Anaesthesia and Intensive Care for Major Burns

Around 140,000 burns/year attend ED in England and Wales. ¹
10% of these are admitted to hospital. ¹
~1/3 of those admitted to hospital need a regional adult burns unit (rest should be managed by plastics if admitted) ¹
14% of hospitalised burn patients die ¹
Most common hospital managed burns are scalds ⁷
A major burn is any burn > 20% BSA ⁷

Risk Factors for Death

Older age
Higher Burned Surface Area
Inhalational Injury (1/4 die) - Inhalational Injury increases risk of death by >3 times. ⁷
Chronic Disease ¹

Burn Pathology

There are three areas to a burn. From inward to outward.

Coagulation
Stasis
Hyperaemia

Coagulation - The point nearest to heat, gets maximum damage, immediate cell death from necrosis and cellular protein coagulation

Stasis - The next point out. Not damaged enough for immediate cell death, but decreased perfusion and increased inflammation, risk of cell death. This bit can be salvageable if early reatment.

Hyperaemia - More vasodilation, shouldn't usually die

Types of Burns

Thermal
Electrical
Chemical
Radiation

Thermal:

Flame
Scald
Contact
Flash

Electrical:

Low Voltage
High Voltage
Electrical

Chemical:

Acids - Coagulate and Necrose Superficial Tissue ⁷
Alkalis - More damaging, reacting with fats causing necrosis, they can keep injuring after agent removed ⁷
Organic Compounds - Dissolving lipid membranes ⁷

All chemical burns need lots of irrigation with water and referral to burns centre. ⁷

Sometimes chemical burns need surgical excision of wounds. ⁷

Radiation:

UV Light
Ionising Radiation

Degrees of Burns

First Degree:

Superficial, epidermal level

Will be bright red and heal within 7 days

Will have fast cap refill and sensation

Second Degree:

Partial Thickness, epidermal and dermal level

Can be split into superficial dermal (blistering), mid dermal (dark pink), and deep dermal (blotchy red)

Third Degree:

Full thickness, going into subcutaneous tissue, looks white and leathery.

Fluid Leak

Starling

Fluid going from capillaries to tissues is controlled by Landis-Starling

Fluid Movement due to filtration across capillary endothelium depends on the balange between hydrostatic pressure gradiant and oncotic pressure gradient. ⁵

In addition you need to consider reflection coefficient and filtration coefficient.

The reflection coefficient is to do with the oncotic pressure gradient. Its how permeable the capillary wall is to protein. The leakier the capillary the lower the reflection coeffiecient. ⁶

The filtration coeffiecient effects the hydrostatic pressure gradient. It's how permeable the capillary wall is to water, and what the area for water transfer is. The leakier the capillary the higher the filtration coeffecient. ⁵

The 4 Starling Forces are:

Hydrostatic Pressure - Capillary - Pc
Hydrostatic Pressire - Interstitium - Pi
Oncotic Pressure - Capillary - pc
Oncotic Pressure - Interstitium - pi

The filtration coefficient is Kf

The reflection coefficient is Ï

The hydrostatic pressure gradient is Pc - Pi

The oncotic pressure gradient is pc - pi

To adjust for leakiness the pressure gradients become:

Flow of Fluid = Kf[(Pc-Pi)-Ï(pc-pi)]

I don't get why filtration coefficient affects both bits, but reflection coefficient only affects second bit.

Fluid Leak in Burns

So here the starling equation shifts as you:

Decrease oncotic reflection coefficient. Leakier to protein due to histamine releace
Increased capillary hydrostatic pressure. I asssume from increased blood supply to affected area
Decreased interstitial hydrostatic pressure. Denaturation of collagen/burned tissue.
Decrease capillary oncotic pressure, as the proteins have leaked out.
Increased interstitial oncotic, as stuff coming from capillaries, and stuff leaking out from burned cells into interstitium

Initial Assessment/Resus

Aims of assessment:

Understand type/extent/depth of burn
Likelihood of inhalation injury
Likelihood of other injuries
PMH ¹

Assess like other trauma patients (C-ABC), a Burns patient is also a TRAUMA patient ¹ ²

Handover with ATMIST:

Age
Time
Mechanism
Injuries
Signs
Treatment ²

Airway Management

Give burn patients 100% O2 through trauma mask
Assess if airway compromised
If airway compromised early it's usually due to GCS not burn ¹

Consider Intubating:

Stridor
Hypoxia
Hypercapnia
GCS < 8
Deep Facial Burns
Full Thickness Neck Burns
Oropharyngeal Oedema ¹

Intubation early is usually easy enough as no swelling yet. ¹

Intubate with uncut size 8 or above (so you can scope later) ¹

Sux? Don't use after 24hrs post burn until up to a year (high risk of hyperkalaemia) ¹

Why does sux cause hyperkalaemia? - Release of K from Extrajunctional Acetylcholine Receptors (AChRs that aren't at the neuromuscular junction ¹

Signs of Airway Burns:

Singed Hairs
Hoarse Voice
Brassy Cough
Sooty Sputum
Stridor
Facial Burns
Tongue/Lip Oedema
Reactive Airway ²

Inhalation Injury

Inhalation injury is the aspiration of:

Superheated Gases
Steam
Hot Liquids
Noxious Products of Incomplete Combustion ¹

You don't see it in flash burns usually, it's more in enclosed burns ¹

Three Types

Above Larynx: Upper Airway Thermal Injury
- Pharynx and Epiglottis with significant thermal injury
- Swells dramatically
- Looks like inspiratory stridor, Voice Change, Swollen Uvula ¹
Below Larynx: Lower Airway Thermal Injury
- Sloughing of airway epithelium
- Mucus Secretion
- Inflamation
- Atelectasis
- Airway Obstruction
- Looks like dysapnoea, coughing, wheezing, secretions +++
- On bronchoscopy is soot, oedema, erythema, heamorrhage, ulceration
- You can wash out with bronchial lavage (1.4% bicarb) to neutralize acid and remove soot ¹
Injury as Result of Noxious Gases
- Carbon Monoxide
- Cyanide ¹

Carbon Monoxide Poisoning

Consider in any unconscious patient and burns in enclosed spaces ¹

Clinically looks like: Coma, N+V, Headache, Low BP, Seizures ¹

Pathology is inhaled carbon monoxide creats carboxyhaemoglobin (HbCO), this shifts oxygen dissociation curve to left, results in tissue hypoxia and metabolic acidosis. ¹

Another problem is HbO2 and HBCO look the same on pulse oximetry, so oxygen saturations is overestimated. ¹

Use ABGs ¹

Treat with 100% oxygen. Speeds clear out of CO from 4 hrs to 1 hr. Hyperbaric O2 speeds clear out to 30mins. ¹

So hyperbaric more faff for 1/2hr sake. Maybe useful for: ¹

Pregnant
Comatose
HbCO > 40%
Patients not getting better with usual treatment ¹

Ventilate patients with HbCO > 25-30% ¹

Cyanide Poisoning

Consider in patients with persistent lactic acidosis ¹

Treat with high flow oxygen and correction of acidosis. Specific antidotes include hydroxocobalamin. ⁷

Breathing

Burns can impair breathing by:

Mechanical Restriction (Deep Circumferential Burns of Chest)
- Managed with Escharotomies of chest
Blast Injuries (Penetrating Trauma, Lung Contusions) ¹

Circulation

Place IV cannulae through unburnt skin if possible ¹

Usually groins spared from burns so consider femoral cannulation ¹

Patients shouldn't be immediately hypotensive from a burn. ¹

Consider bleeding from other injuries! ¹

Disability

Assess as usual ¹

Reasons for Reduced Conscous:

Hypotension (Hypovolaemia)
Head Injury
Noxious Gas Poisoning
Hypoxia
Hypoglycaemia
Medical Conditions ²

Exposure

Remove any jewellery/watches (there will be swelling later) ¹

Examine front and back to get estimate burn area/find other injuries ¹

Burn Areas can need cooling up to 3hrs after injury, through irrigation with cold water. ²

Keep covered as much as possible, burnt patients get cold easily ¹

Cover Burn Areas loosely with clingfilm. It helps pain and infection. ²

Estimating Burn Surface Area

Lund-Browder Chart
Rule of Nines (good for adults) ¹

Adult Area	Percentage
Head	9%
Chest	18%
Back	18%
Arms	9% each
Legs	18% each
Perineum	1% ¹

Child Area	Percentage
Head	18% (double of adults)
Chest	18%
Back	18%
Arms	9% each
Legs	13.5% each (3/4 of adults)
Perineum	1% ¹

Children are assumed to have adult proportions by age 10. From age one up, remove 1% from head and add it to lower limps. ³

Erythema doesn't count, needs to be partial or full thickness to count. ²

Remember the 1% rule, that the patients hand = 1% of patients BSA. ³

If it's less than 1% of body then measure in mm ³

Another way is called Serial Halving, it's taught to Armed Forces. It's about as good as rule of nines to work out who needs to go where. ³

Serial Halving:

Is burn more than half of TBSA? If yes will need highest level of burn care
Is burn 25-50% of TBSA - If less than 50% ignore the unaffected half. Does the burn cover more than half of the affected half? If yes will need IV fluids and specialist burn care.
If no to all those things then may still IV fluids but may not need specialist centre. ³

Serial Halving is useful for triage only, as it can sometimes over simplify. ³

Complex Burns To Refer

Extremes of Age <5/>60
Face/Hands/Feet/Perineum
Flexures of Joints
Circumferential Burns (Neck/Torso/Limbs)
Inhalational Injury
Chemical Burns
Radiation Burns
High Pressure Burns
Non Accidental Injuries
10%+ BSA
Significant Comorbidities
Associated Crush/Fracture/Head/Penetrating Injuries ¹

Fluids

Give fluids if burns are >15% BSA or >10% if smoke inhalation ¹

Use Parkland Formula: 4ml /kg / %burnsurfaceare = First 24hr requirement ¹

Parkland was created in Dallas in 1960s ⁴

Give half in first 8 and half in next 16 ¹

Use Hartmanns ¹

Urine Output Target 0.5ml/kg/hr ¹

Burns can cause rhabdomyolysis ⁷

Analgesia

Full Thickness is Painless but no-one has just full thickness. ¹

Give IV morphine titrated to response ¹

Anaesthesia and Surgery

This needs to be done by an MDT approach in burns unit. ¹

The questions are when to debride, when to perform escharotomy. ¹

Escharotomy

Needed when full thickness circumferential burn, causing ischaemia and compression of compartment. ¹

If >40mmHg in compartment then decompress ¹

Anaesthesia

Placing stickers for ECG can be difficult, can get around with subcut needles attached to crocodile clips ¹

Placing pulse ox can be difficult, can get around with pulse ox on nose/lips/tongue ¹

You need art line for major excisions. Consider cardiac output monitor. ¹

Blood loss to be expected. 50-100ml per % area excised. Plus patients will be thrombocytopaenic and coagulopathic. ¹

There will be a SIRS response. ¹

Critical Care Managment

In first two days after resus for major burns, there will be hypermetabolic, immunosuppresed, SIRS state ¹

Fluid Resus/Electrolyes

You want to avoid end-organ ischaemia as always, use the Parkland formula as a guide. ¹

Use invasive monitoring. ¹

Fluid Creep can result in complications for burns patients with: ¹

Excessive Oedema at Burns
Abdominal Compartment Syndrome
Unburned Limbs Neeeding Fasciotomies
Pulmonary Oedema and Prolonged Ventilation ¹
Elevated intraocular pressure - orbital compartment syndrome! ⁴

Other electrolyte issues: ¹

Low Potassium/Phosphate/Calcium/Magnesium ¹

Burn Shock is a combination of hypovolaemic, distributive, and cardiogenic shock - refractory to iv fluids ¹

Mechanical Ventilation

Use usual lung protective strategies ¹

No point for prophylactic steroids/antibiotics ¹

Inhalation injury consider: Tracheal Intubation, Aggressive Pulmonary Toilet, Bronchodilator Therapy, Bronchoscopic Lavage ¹

Hypothermia

When you have a large burn your baseline temperature increases to 38.5, so if your core temp is 37 you're hypothermic ¹

Keep in a warmed room, with warmed air, warmed blankets, and warmed fluids ¹

This will keep warm and minimise the basal metabolic rate ¹

Metabolic/Nutrition

Your basal metabolic rate will go up. It will go up in bigger burns and with more infection. It will peak at one week. It can stay for 2 years. ¹

Early feeding improves survival in burn patients. ¹

They have high protein and high carb needs. To minimise muscle loss, improve immunity, minimise infections. ¹

Infections

Is a major cause of mortality in major burns. ¹

It's hard to work out who is infected and who is just prolonged SIRS from burns. ¹

Modify your infective criteria to:

Temp > 39
HR > 110
RR > 25
Hyperglycaemia
Thrombocytopaenia (<100 - 3 days after resus)
Gut Failure > 24hr ¹

Possible Future Therapies?

Haemofiltration to remove cytokines?
Vitamin C to scavenge free radicals?

Psychological Care/Rehab

You need:

Physios
Psychologists
Nurses
Councillors
OTs ¹

Basically the same as for any critical illness! ¹