Burns

Question 1

What are the four basic etiologic categories of burns?

Answer 1

Thermal, chemical, electrical, radiation

Question 2

What are the three ways heat is transferred to the tissues with thermal burns?

Answer 2

Convection: airborne heat transfer.
Conduction: direct transfer with a hot object.
Radiation: from electromagnetic energy.

Question 3

What are the classifications of burn depth?

Answer 3

First degree: only epidermis, dermis intact, no scarring.
Second degree: extension to dermis.
Third degree: extension to subcutaneous tissues.
Fourth degree: extension to muscle or fascia.
Fifth degree: Extension to bone.

Alternatively burns can be classified as partial thickness (first and second degree) or full thickness (third degree).

Question 4

At what temperature do partial and full thickness burns occur?

Answer 4

Failure of cell membrane sodium pump occurs at 40 degrees, partial thickness burn at 60 degrees for 1 second, full thickness at 70 degrees for 1 second.

Question 5

What is the rule of nines when assessing burn surface area?

Answer 5

Division of the body into regions that are multiples of 9%.

Head and neck: 9%
Each forelimb: 9%
Each hindlimb: 18%
Dorsal trunk: 18%
Ventral trunk: 18%

Question 6

What is the calculation for total surface area burn using a veterinary burn card (size of a credit card)?

Answer 6

%TBSA burn = (number of cards x 0.45)/meters squared

Note: meters squared is based off body weight conversion chart.

Question 7

What are the three regions/zones recognized after thermal burning of the tissue?

Answer 7

Zone of coagulation: inner zone, no viable tissue remains.

Zone of stasis: region of decreased perfusion due to red blood cell damage and decreased vascular luminal diameter due to increased interstitial pressure from capillary leakage. Tissues are vulnerable to progression to necrosis with further injury.

Zone of hyperemia: primary area of the inflammatory response to the burn, characterized by vasodilation, edema, influx of inflammatory cells.

Question 8

List 8 body systems that are systemically affected by a thermal burn injury.

Answer 8

1. Pulmonary system
2. Cardiovascular system
3. GI system
4. Renal system
5. Hematopoietic system
6. Immune system
7. Neurologic system
8. Metabolic and endocrine system

Question 9

Is the majority of pulmonary disease following thermal burn injury secondary to thermal or toxic damage?

Answer 9

Toxic damage. Particularly carbon monoxide inhalation.

Question 10

What are the three mechanisms by which carbon monoxide exerts toxic effects?

Answer 10

1. Preferentially binding to hemoglobin.
2. Carboxyhemaglobin formation resulting in a leftward shift of the oxyhemaglobin dissociation curve.
3. Binding of carbon monoxide with myoglobin reducing oxygen availability to muscle.

Question 11

What are some pathologic changes in the lungs that occur secondary to thermal burn injury?

Answer 11

Accumulation of fluid, mucus and neutrophils in the airways secondary to increased vascular permeability, pulmonary edema, atelectasis, decreased alveolar ventilation, decreased lung compliance. These result in acute respiratory distress syndrome.

Question 12

What are the two factors that contribute to hypovolemia following serious thermal burn injury (>25% total body surface area)?

Answer 12

Evtravasation (systemic response to burn injury with 30% loss of plasma volume) and evaporation (fluid losses from a burn are 3 - 20 times greater than that from intact skin).

Hypovolemia and hyperviscosity result in hypoperfusion and thrombosis leading to tissue hypoxia and metabolic acidosis.

Question 13

What effect do large burns have on the myocardium?

Answer 13

Decreased left ventricular contractility due to ionic derangements secondary to endotoxin and cytokine release (increased myocyte calcium and cytoplasmic sodium), direct myocardial damage and decreased cardiac output from carbon monoxide intoxication.

Question 14

What are the effects of a large thermal burn on the GI system?

Answer 14

Compromised GI barrier function with translocation of gut bacteria and endotoxins. Impaired GI motility and hepatic function.

Question 15

What are the effects of a large thermal burn on the renal system?

Answer 15

Can cause acute polyuric renal failure. Associated with a high mortality rate. Caused by numerous factors, including; hypotension, hypoalbuminemia, hemoglobinemia, myoglobinemia, sepsis, use of nephrotoxic antibiotics.

Question 16

What are the effects of a large thermal burn on the RBCs?

Answer 16

Burn anemia is the result of loss of RBCs (10% of circulating RBCs can be trapped in burn, intravascular hemolysis secondary to membrane damage), and decreased erythropoiesis.

Question 17

What are the effects of a large thermal burn on the immune system?

Answer 17

Negative effects on lymphocyte production and function, induction of hyperinflammatory macrophage and neutrophil phenotypes.

Question 18

What are the effects of a large thermal burn on the neurologic system?

Answer 18

Hyperalgesic state, massive sympathetic discharge, role of peripheral nociceptors on the local inflammatory response (substance P is involved in increasing vascular permeability and pulmonary edema).

Question 19

What are the effects of a large thermal burn on the metabolic and endocrine systems?

Answer 19

Hypo and then hypermetabolic state (increase in energy expenditure by 100%, hypothalamic set point is increased by 1.1 to 2.2 degrees, increased protein catabolism, increased gluconeogenesis and relative insulin resistance).

Question 20

What is the optimum temperature for cold water in immediate thermal burn injury first aid?

Answer 20

15 degrees. Cooling with ice is contraindicated (no improvement over control subjects).

Question 21

What is burn shock and how is it treated?

Answer 21

Generalized cardiovascular collapse associated with severe burn. Should be treated with fluid resuscitation (maintain urine output between 1-2 ml/kg/hr).

Question 22

Why is it postulated that Lactated ringers, hetastarch and dextran-40 should be avoided in the immediate post-burn period?

Answer 22

D-lactate in Lactated ringers is proposed to increase neutrophil activation. This is also seen with hetastarch and dextran-40.

Question 23

What are some clinical signs that might suggest inhalation injury in burns patients?

Answer 23

Hypoxia, crackles, rales and wheezes are often only seen in the most severely affected patients.

May present with tachycardia, tachypnea, hypothermia, and pink mucous membranes.

Question 24

How is inhalation injury treated following thermal burn?

Answer 24

Nebulization, coupage (every 4 hours), bronchoscopic lavage, oxygen therapy (displaces carbon monoxide from hemoglobin, spares the respiratory muscles from fatigue), bronchodilators (to reduce bronchospasm and improve mucus clearance), antimicrobials (pneumonia common sequelae of inhalation damage).

Question 25

How does oxygen therapy affect the half life of carbon monoxide?

Answer 25

An FiO2 of 40% decreases the half life from 4 hours to 1 hour. Hyperbaric oxygen therapy decreases the half life to 30 minutes.

Question 26

What bronchodilators have been used in the treatment of burn patients?

Answer 26

Aerosolized epinephrine, aerosolized N-acetylcysteine (use is controversial as although a powerful mucolytic is also a respiratory tract irritant).

Question 27

What are the three classifications of burn pain?

Answer 27

Procedural pain (most intense), background pain, breakthrough pain.

Can also be classified based on temporal classifications: acute phase (initial debridement), healing phase (until the wound is reepithelialized), rehabilitation phase (months to years).

Question 28

How can breakthrough burn pain be addressed?

Answer 28

Shortening the dosing interval of opioids, use of a CRI, increasing the dose.

Question 29

Is persistent hyperglycemia in burn patients associated with increased mortality?

Answer 29

Yes

Question 30

What are some treatment strategies to minimize the hyperglycemia and hypercatabolic state associated with severe thermal burn injury?

Answer 30

Keep patient warm, cover wounds to prevent heat and evaporative loss, ensure adequate analgesia to reduce catecholamine release, carbohydrate and protein (approximately twice normal requirement) supplementation +/- insulin and alpha adrenergic antagonist therapy (i.e. propanolol).

Question 31

What are some methods for burn debridement?

Answer 31

Surgical debridement (layered or tangential), ultrasonic debridement, hydrosurgical debridement, autolytic debridement.

Question 32

What is the application of cerium nitrate in large burn treatment?

Answer 32

Used in instances where immediate surgical debridement is not possible. Forms a hard, impermeable eschar at the burn surface, reducing the risk of infection and sepsis. Subsequent escharectomy shows an underlying healthy wound bed.

Question 33

What is Joule’s law as it relates to electrical burns, and what is its clinical significance?

Answer 33

Indicates that energy delivery to tissue is proportional to the resistance, duration of exposure and amperage (J = I(squared)RT.
Higher resistance tissues such as bone may be more severely affected. This may not be externally noticeable.

Question 34

What are the three mechanisms by which frostbite causes tissue damage?

Answer 34

Tissue freezing, hypoxia, release of inflammatory mediators.

Question 35

What temperature of water should be used in initial first aid for frostbite injury?

Answer 35

Immersion in tepid or lukewarm water at 40 to 42 degrees.