Burns Flashcards
Burns are classified according to
1) Depth
2) Extent of skin and tissue destruction
3) Total body surface area involved (TBSA)
Burn Classifications (Degrees)
Partial Thickness
1st degree
- Involve skin and epidermis only
- These will heal spontaneously
2nd Degree
- Skin, epidermis, and dermis involved
- May or may not need grafting
3rd Degree
- Skin, epidermis, dermis, and SQ tissue involved
- Definitely needs grafting
4th Degree
- Skin, epidermis, dermis, SQ tissue, and muscle involved
Rule of Nines
Head = 9% TBSA Upper extremities = 18% TBSA Trunk = 36% TBSA Lower extremities = 36% TBSA Pediatrics are an exception to this rule (look at the image in lecture)
What burns are considered major burns?
Full thickness > 10% TBSA Partial thickness > 25% TBSA OR Partial thickness > 20% in these cases: - Extremes of age - Burns of hands, feet, perineum - Inhalational, chemical, electrical burns - This is because these burns are associated with co-existing disease
What does the national burn registry say about burns and mortality?
If the age of the patient + the TBSA is > 115, the expected mortality is > 80%
In closed-spaced thermal injuries, what are we worried about?
Airway injury
In open, accidental burn injuries, what are we worried about?
These are often associated with multiple co-existing injuries (like from an MVA where the car caught on fire or something)
Electrocution may lead to
- Severe fracture
- Skeletal injury
- Hematoma
- Visceral injury
- Cardiac injury
- Superpowers
Initial treatment of the burn patient should involve
The ABCs! Just like any other trauma.
Don’t forget to look for co-existing traumas.
Airway management in the burn patient
- ALWAYS be thinking about upper airway injury if the burn occurred in a closed space or if the patient is unconscious
- Diagnosis of airway injury is based on H&P –> knowing how the injury occurred and by DVL or fiberoptic bronchoscopy)
- Damage to soft tissues of the respiratory tract and trachea can make intubation difficult
- Thermal injury followed by aggressive fluid resuscitation can make glottic edema worse
- Give 100% O2 via FM
- ETT is indicated if massive burn, stridor, rest distress, hypoxia/hypercarbia, altered LOC, or pt is likely going to deteriorate
- AFO under topical anesthesia is safest approach for adults
- Pediatrics have narrow airways, and thus low threshold for intubation
S/S that would suggest upper airway damage to you
- Facial burns
- Singed facial hair
- Hoarseness / dysphonia
- Cough
- Soot in mouth or nose
- Difficulty swallowing
- CXR (will be normal initially, but later will show pulmonary edema or infiltration)
Lower airway involvement may result in
decreased surfactant, decreased mucociliary function, mucosal necrosis and ulceration, tissue sloughing.
Tissue sloughing will result in bronchial obstruction, air trapping, and pneumonia!
When may ARDS, pneumonia, and PE develop post-burn?
ARDS = 1-5 days post-burn
Pneumonia and pulmonary edema may occur > 5 days post-burn
What sort of tests should be ordered if inhalation injury is suspected?
DVL and bronchoscopic exams, CXR, ABGs, PFTs
How would you treat hypoxia in burn patients?
PEEP Airway humidification (airways may be dried out from injury --> desiccation leads to poor diffusion across membranes) Bronchial suctioning / lavage Bronchodilators Antibiotics Chest PT Nitic oxide (NO)
Smoke inhalation injury
This is just damage from the smoke alone. Not thermal injury.
- Occurs with face/neck burns and fires in closed spaces
- Chemical pneumonitis occurs –> similar picture to aspiration of gastric contents
- Pts will have a “honeymoon period” –> CXR looks good for the first 48 hours. Misleading because then they may still develop pneumonitis when you think they’re in the clear.
- Decreased PaO2 on RA is first sign of smoke inhalation injury
- Increased sputum production (ciliary cells trying to get that shit out of there)
- Pt may have rales or wheezing
Hypoxia in burn patients with inhalational injury
First 36 hours = high risk of pulmonary edema secondary to pre-intubation bronchial obstruction
Days 2-5 = Expect atelectasis, bronchopneumonia, maximum airway edema 2/2 sloughing of airway mucosa and thick secretions, distal airway obstruction
> 5 days = nosocomial pneumonia, high metabolism respiratory failure, and ARDS
Restrictive disease pattern may result from
Circumferential burns of chest and upper abdomen. Restriction begins to occur as eschar contracts and hardens.
This is often found with smoke inhalation
CO poisoning
CO has affinity for Hgb __ times more than O2
200x more
CO causes a shift of the dissociation curve to the
LEFT
This impairs the ability of O2 to unload from Hgb to the tissues
CO interferes with
Mitochondrial function
- -> Uncouples oxidative phosphoylation
- -> Reduces ATP production
- -> Results in metabolic acidosis
Effect of CO on the heart
May act as a myocardial toxin and prevent the survival of cardiac arrest
Management of CO toxicity patients
- O2 sats may look normal, but remember that they can’t unload the O2 to the tissues!
- Respiratory effort is often normal
- May have cherry-red coloration of blood, but this may not be present if CO 30% and the pt is hemodynamically and neurologically stable
Cough level > ___% is not compatible with life
60%
Levels of CO toxicity and associated s/s
60% = DEATH
How do burn patients get cyanide toxicity?
CN is often produced as synthetic materials burn
CN toxicity and the burn patient
- Pts will get metabolic acidosis
- Altered LOC with agitation and confusion or coma
- CV depression / arrhythmia risk
- Diagnosis is confirmed with blood levels > 0.2mg/L
- Death occurs with CN levels > 1.0mg/L
- CN has a half-life of 60 minutes
- The treatment of choice is O2!
- Other treatments include amyl nitrate, sodium nitrate, and thiosulfate
Systemic results of burns include
Immune suppression, hypermetabolism, protein catabolism, sepsis, and MSOF
Mediators released locally (from minor burns)
Histamine Prostaglandins Bradykinin NO Serotonin Supstance P
Mediators released systemically (from major burns)
Cytokines (interleukins and TNF)
Endotoxins
NO
Metabolism in the burn patient
- Increased metabolic rate proportional to TBSA burned (can double in a TBSA of 50%)
- Increase in core body temp reflects the increase in metabolic rate
- Loss of skin results in loss of vasoactivity, piloerection, and insulation functions
- High evaporative fluid losses (carries heat with it)
- Increased caloric consumption
Daily evaporative fluid loss in burn patients
4000mL/m2
Effect of anesthesia on body temperature in burn patients
Causes vasodilation and decrease in metabolic rate, both of which result in hypothermia
CV stressors after burn injury
- Severe decrease in CO for the FIRST 24 hours
- Circulating LMW myocardial depressant factor
- Third spacing results in hypovolemia, which intense vasoconstriction as compensation
- Hemolysis of erythrocytes
- Increased metabolic demands but decreased O2 supply
- Hyperdynamic state results AFTER 24 hours –> high output CHF –> see increased BP, HR, and CO 2X normal
- HTN seen can be SEVERE
Other end organ complications seen with severe burn injuries
GI
- Ileus, ulceration, and cholecystitis
Renal
- Decreased GFR, RBF 2/2 hypovolemia and decreased CO
- Loss of Ca, K, and Mg
- Retention of Na and H2O (trying to stay euvolemic with all these evaporative losses!)
Endocrine
- CATECHOLAMINE RELEASE
- Increased corticotropin, ADH, renin, angiotensin, aldosterone, glucagon, +/- insulin, hyperglycemia (at risk for nonketotic hyperosmolar coma, esp if on TPN)
Blood and Coagulation
- Increased viscosity (high evaporative loss)
- Increase in clotting factors (fibrinogen, V, and VIII, fibrin split products
- At risk for developing DIC
- Hct usually goes down 2/2 hemolysis
Response to catecholamines in burn patients is
reduced
Hypovolemic shock is often accompanied by
cardiogenic shock
Edema in burn patients
Increased microvascular permeability results in proteins filling the interstitial space
Edema formation stops at 18-24 hours as long as adequate fluid resuscitation has occurred
Loss of fluid from the vascular compartment in the first 24 hours =
4mL/kg for each 1% of TBSA burned
Fluid maintenance for those with TBSA
150% of normal maintenance rate
Risks associated with overdoing your fluid resuscitation
Can worsen airway edema, increase chest wall restriction, and contribute to abdominal compartment syndrome
Types of fluids to use
First 24 hours = crystalloids only
> 24 hours, consider 5% albumin if plasma proteins are highly diluted.
Remember that edema should correct itself within 18-24 hours if the pt is adequately fluid resuscitated. This is probably d/t repair of the microvasculature. In the first 24 hours, giving albumin will leak out and probably worsen edema. So we wait on albumin until > 24 hours.
Doses for fluid resuscitation
Albumin 5% (after first 24 hours)
0.3 - 0.5 mL/kg Dose in this range based on extent of burn
Parkland Formulation
4ml / kg / % burned (Give in first 24 hours)
Modified Brooke Formula
2mL/kg/% burned (Give in first 24 hours)
Give 50% of volume in first 8 hours
25% in second 8
Another 25% in the third 8
This is very similar to our fluid deficit replacement!
Goals of fluid resuscitation in burns
UO 0.5-1 mL/kg/hr
HR 80-140 (consider age)
MAP > 60
Base deficit
If perfusion and UO is still poor despite adequate fluids, what else can you do?
Low dose dopamine
5mcg/kg/min
Electrolyte abnormalities in burn patients
Hyper or hyponatremia
Altered iCa, Mg, and K+
Anesthesia for echarotomies
These are performed multiple times, especially from days 2-14 after burn injury
- Maintain Hct (often need transfusions)
- Coagulopathy
- Temperature (fluid warmer and bair)
- Fluids and electrolyte correction
- Hypermetabolic states means higher O2 requirement, ventilation, and nutrition requirements
- Risk of GI ileum (aspiration risk)
Monitors: May be difficult to place d/t extensive burns providing limited access
- Need large bore IV access (may need to place in abnormal places)
- Increase the room temp to 28-32 degrees
- Minimize blood loss (topical/SQ epi, only address 15-20% TBSA per procedure, use tourniquets
- Treat complications of massive transfusion (coagulopathy and hypocalcemia)
Pharmacology changes in burn patients
- HIGH opioid requirement (ideal anesthetic choice is isoflurane with large dose opioid)
- Serial debridements calls for ketamine or regional via indwelling catheter
Muscle relaxants
- In first 24 hours, there is normal response to all paralytics
- Avoid sux 24 hours to 1 year post-burn injury
- Resistance to most NDMRs in burns > 30% TBSA
