Burns Flashcards
What are the four basic etiologic categories of burns?
Thermal, chemical, electrical, radiation
What are the three ways heat is transferred to the tissues with thermal burns?
Convection: airborne heat transfer.
Conduction: direct transfer with a hot object.
Radiation: from electromagnetic energy.
What are the classifications of burn depth?
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).
At what temperature do partial and full thickness burns occur?
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.
What is the rule of nines when assessing burn surface area?
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%
What is the calculation for total surface area burn using a veterinary burn card (size of a credit card)?
%TBSA burn = (number of cards x 0.45)/meters squared
Note: meters squared is based off body weight conversion chart.
What are the three regions/zones recognized after thermal burning of the tissue?
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.
List 8 body systems that are systemically affected by a thermal burn injury.
- Pulmonary system
- Cardiovascular system
- GI system
- Renal system
- Hematopoietic system
- Immune system
- Neurologic system
- Metabolic and endocrine system
Is the majority of pulmonary disease following thermal burn injury secondary to thermal or toxic damage?
Toxic damage. Particularly carbon monoxide inhalation.
What are the three mechanisms by which carbon monoxide exerts toxic effects?
- Preferentially binding to hemoglobin.
- Carboxyhemaglobin formation resulting in a leftward shift of the oxyhemaglobin dissociation curve.
- Binding of carbon monoxide with myoglobin reducing oxygen availability to muscle.
What are some pathologic changes in the lungs that occur secondary to thermal burn injury?
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.
What are the two factors that contribute to hypovolemia following serious thermal burn injury (>25% total body surface area)?
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.
What effect do large burns have on the myocardium?
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.
What are the effects of a large thermal burn on the GI system?
Compromised GI barrier function with translocation of gut bacteria and endotoxins. Impaired GI motility and hepatic function.
What are the effects of a large thermal burn on the renal system?
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.
What are the effects of a large thermal burn on the RBCs?
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.
What are the effects of a large thermal burn on the immune system?
Negative effects on lymphocyte production and function, induction of hyperinflammatory macrophage and neutrophil phenotypes.
What are the effects of a large thermal burn on the neurologic system?
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).
What are the effects of a large thermal burn on the metabolic and endocrine systems?
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).
What is the optimum temperature for cold water in immediate thermal burn injury first aid?
15 degrees. Cooling with ice is contraindicated (no improvement over control subjects).
What is burn shock and how is it treated?
Generalized cardiovascular collapse associated with severe burn. Should be treated with fluid resuscitation (maintain urine output between 1-2 ml/kg/hr).
Why is it postulated that Lactated ringers, hetastarch and dextran-40 should be avoided in the immediate post-burn period?
D-lactate in Lactated ringers is proposed to increase neutrophil activation. This is also seen with hetastarch and dextran-40.
What are some clinical signs that might suggest inhalation injury in burns patients?
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.
How is inhalation injury treated following thermal burn?
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).
