Chapter 76 - Burns Flashcards

1
Q

how do you calculate the total body surface area in burns?

A

Rule of 9’s

Head/neck - 9%

RUE - 9%

LUE - 9%

RLE - 18%

LLE - 18%

Front of body - 18%

Back of body - 18%

genitals - 1 %

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2
Q

What are the pathophysiologic effects of major burns on cardiac, resp, heme/coagulation, renal, immune, and metabolism system?

A

Burns - associated with systemic release of inflammatory mediators: histamine, bradykinin, vasoactive amines, and interleukins –> affect all systems.

1) Cardiac

  • Early - hypovolemic shock
    • inflam mediators -> inc capillary permeability -> third space -> intravascular depletion
  • CO decreased, SVR increased
    • 2/2 circulating mediators
  • Late (24-48hr later) - SIRS
    • CO increased, SVR decreased

2) Lungs

  • direct injury - upper airway swelling, smoke inhalation injury
  • indirect injury - pulm edema & pulm HTN 2/2 leaky capillary membrane in lungs

3) Kidneys
* AKI 2/2 decrease renal blood flow 2/2 hypovolemia and increase R-A-A = systemic vasoconstriction
4) heme/coag
* DIC (activated by inflamm mediators)
5) hypermetabolism
* increase metabolic rate, increase O2 utilization, increase Co2 production, impaired thermoregulation

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3
Q

What fluid would you use and how much would you want to transfuse for an adult burn patient? (parkland formula)

A
  • LR = fluid of choice since it most closely resembles human plasma

Parkland Formula

  • 4 ml / kg / % TBSA burned
  • half of fluid administered in first 8 hours
  • remaining half given over next 16 hours
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4
Q

for initial resucitation, would you use colloid or crystalloid?

A
  • burn injury is associated with large inflammatory mediator release, causing permeable capillary membranes –> edema and third spacing
  • Do NOT give colloids in first 24 hours, not more effective in restoring volume than crystalloids in this time frame
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5
Q

What is a possible complication of fluid resuscitation in a burn patient?

A
  • burn patients are intravascularly depleted 2/2 third space losses and evaporation of fluids, as well as bleeding.
  • they have leaky capillaries from systemic inflammatory mediator release
  • fluids can worsen interstital edema:
    • increase abdominal compart pressure
    • increase orbtial pressure
    • increase extremitiy compartment pressure
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6
Q

How do you diagnose smoke inhalation injury?

A

Clinical features + bronch

Clinical features

  • facial burn
  • singed nasal hairs
  • carbonaceous sputum
  • hoarseness
  • respiratory distress

FOB = Gold Standard

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7
Q

what are the anesthestic concerns with smoke inhalation injury, how do you manage it?

A

Smoke

  • casues swelling of upper airway, can quickly lead to airway obstruction
  • damages respiratory tract and alveoli –> bronchospasm, edema, mucous membrane ulceration

Mgmt

  • goal - maintain airway patency, maximize gas exchange
  • Secure Airway - protection and/or resp failure
  • Mech Vent
    • ​​lungs are damaged from smoke injury –> minimize barotrauma using ARDS protocol
    • consider permissive hypercapnia to minimize airway pressure
    • PaO2 > 60 is acceptable -> reduce O2 toxicity
  • supportive care
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8
Q

Pathophys of CO?

A

CO Pathophys

  • higher affinity for HgB than O2
  • 1) displaces O2 from HgB
    • decrease oxygen-carrying capacity of HgB
  • 2) shifts O2-HgB dissociation curve to left
    • reduces unloading of O2 to tissues
  • 3) binds to cytochrome oxidase and impairs activity of intracellular enzymes
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9
Q

Dx and TX of CO poisioning?

A

DX:

  • measure carboxyhemoglobin levels
  • cooximeter - measure oxyhemo and carboxy hemo
    • normal pulse ox cannot differentiate betwen oxy and carboxy -> normal SaO2

Tx:

  • supplemental O2
  • 100% FiO2 = eliminates CO 60-90 min
  • hyperbaric O2 = eliminates CO even faster
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10
Q

Discuss Cyanide toxicity pathophys and tx

A

CN toxicity

  • inhibits cytochrome oxidase in mitochondria –> prevents them from using O2 –> prevents ability to generate ATP.
  • Metabolic Acidosis and increased SVO2

Tx:

  • supplemental oxygen
  • hemodynamic support
  • give meds that bind to cyanide and eliminate from body (meds that compete for cyanide to prevent it from binding to cytochrome oxidase)
    • ​sodium thiosulfate
    • amyl nitrate
    • cyanocobalamin
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11
Q

patient comes with severe burn 5 hours ago, how would you assess his airway and how would you intubate this patient? How would you intubate a peds burn patient?

A

1) H&P

  • emergent intubation required?
    • Respiratory distress, stridor, hypoxemia/hypercarbia
    • If yes -> RSI
  • airway exam, pre-existing airway abnormalities, prior intubation history, history of head/neck surgery
  • pre-op FOB of nasopharyngeal airway to look at structures, look for edema and impending airway obstruction

Airway

  • no airway abnormalitiy –> RSI
  • abnormal airway or stable upper airway obstruction –> Awake FOB
  • Peds pts are not cooperative –> inhaled induction with nonpungent voltaile - sevo. intubate with DL, glidescope, asleep FOB, etc..
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12
Q

Patient had a severe burn injury 5 hours ago, you plan to do RSI, would you use succinylcholine?

A
  • Burn injuries are associated with upregulation of extrajunctional nicotinic cholinergic receptors at NMJ
  • SUX places pt at risk for hyperkalemic cardiac arrest
  • **Safe to use SUX within first 24 hours after burn injury**
    • AVOID SUX THEREAFTER
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13
Q

A patient with a burn injury 4 days ago comes to the OR for exicsion and grafting. Explain the surgical management of burns and appropiate timing of surgery.

A

Overview

  • burns produce eschar formation –> nidus for inflammation and infection –> leads to sepsis

Timing of surgery

  • Early exicision and grafting (2-5 days after burn injury) –> shown benefits in terms of survival, incidence of sepsis, length of hospitalization
    • day 1-2 fluid resucictate and optimze for surgery

Surgery

  • excision of eschar until healthy wound bed developos.
  • autograft from donor site used to cover wound
  • major bleeding associated with autograft sites and exicision of eschar.
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14
Q

patient comes to your OR after suffering burn injury 4 days ago. He is fluid resusciated pre-operatively in the unit, is intubated as well. His burn wound is 40% of total body surface area (TBSA). What are your anesthetic considerations?

A

1) Airway
* if patient is intubated, how was the intubation performed
2) Muscle relaxants

  • burn associated with upreg of extrajunc AcH recep at NMJ
  • avoid SUX 24 hours after burn injury
  • use NMBD –> large doses required due to decreased sensitivity from inc of extrajunc AcH recep

3) Blood Loss

  • rapid and massive blood loss
  • major fluid shifts associated with large burn surgery
  • blood products readily available, constant commun with surgical team

4) Hypothermia

  • skin barrier is destroyed –> lose heat and water
  • hypothermia –> negative effects such as coagulation, inc hypermetabolism, inc O2 consumption
  • Inc room temp, monitor core temp, IV fluid warmer, forced air warming devices
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