Burn Anesthesia 848th FST

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Burn Anesthesia848th FST
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Burns and the FST

• Burn patients will need increased fluid therapy
  and repeated debriedments
• Increases demands on personnel and supplies
• The treatment and evacuation of burns is a key
  concern in pre-deployment planning

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Burns and the FST

• Increased use of vehicles sets stage for burn
  injuries by fuel and ammunition fires
• Aviation and armor troops are at greater risk
• Burns from closed vehicles (e.g. tanks, APC,
  etc.) increase the possibility for severe
  inhalational injuries
• Need for aggressive airway management

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Primary Survey

• ABCs of burn resuscitation
• Airway
• Breathing
• Circulation

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Airway and Breathing

• Early intubation required to treat 4 causes of
  respiratory dysfunction
• 1. CO poisoning
• 2. Upper airway edema
• 3. Subglottic thermal and chemical burns
• 4. Chest wall restriction

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CO Poisoning

• Results of combustion of synthetic materials
• Leading cause of death associated with fires
• Causes tissue hypoxia due to
• Binds to Hgb 200x more readily than O2 in alveoli
• Creates a leftward shift of oxygen Hgb
  dissociation curve
• Impairs O2 unloading at tissue level

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CO Poisoning

• Signs and Symptoms
• 1. High index of suspicion (most important)
• 2. Headache, SOB, N/V, angina, tachypnea
• 3. Cherry red appearance of mucous
  membranes and nailbeds
• 4. Persistent metabolic acidosis with
  adequate volume resuscitation and CO

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CO Poisoning

• Treatment
• Early intubation and ventilation with 100 FiO2
• O2 displaces CO from Hgb 50 for every 20-30 min.
  of 100 FiO2

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CO Poisoning

• Other
• Normal COHgb lt7
• Coma COHgbgt50
• Standard 2 wave pulse Ox will give a false high
  reading

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Upper Airway Edema

• Most pronounced first 8 hrs. postburn
• All supraglottic tissues may be affected

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Upper Airway Edema

• Signs and symptoms
• High level of suspicion
• Hoarseness
• Facial burns
• Soot in nasal or oral secretions
• Persistent cough
• Wheezing

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Upper Airway Edema

• Treatment
• Early intubation before edema makes it impossible
• Humidified O2 to help clear secretions
• Bronchodilators to manage bronchospasm
• Elevate HOB 20-30 degrees
• Decrease head and neck edema

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Subglottic Thermal and Chemical Burns

• Thermal burns
• Rare except in cases of inhalation of steam and
  explosive gases
• Amount of injury R/T temperature of inhaled gases

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Subglottic Thermal and Chemical Burns

• Chemical burns
• Dangers not only from local irritation but from
  systemic poisoning too
• Agents stink (e.g. chlorine, ammonia, sulfur)
• Short exposure can cause much pulm. damage

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Subglottic Thermal and Chemical Burns

• Signs and symptoms
• Bronchspasm
• Edema of the airways
• Decreased pulmonary compliance
• Poor mucociliary clearance
• Airway plugging secondary to sloughing
• Atelectasis
• Infection
• Pulmonary edema
• Myocardial irritation

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Subglottic Thermal and Chemical Burns

• Treatment
• Early intubation and mechanical ventilation with
  PEEP
• Corticosteriods
• Pulmonary toilet
• Humidified O2
• Antibiotics not necessarily useful

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Chest Wall Restriction

• Found mostly with circumferential 3rd degree
  burns
• Loss of elasticity incr. work of breathing
  required to maintain FRC and Vt.
• Symptoms may incr. 10-12 hrs postburn secondary
  to maximum edema formation
• Further compressing thoracic volumes

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Chest Wall Restriction

• Treatment
• Ventilation and mechanical ventilation
• Escharotomies

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Airway and Breathing Summary

• Early intubation and ventilation are the rule of
  the day
• Humidified O2, bronchodilators, and
  corticosteriods may be usefulATBs may not
• Distal airway burns are seen within 12-24 hrs and
  resemble pulm edema
• Other reasons for intubation include
• Difficulty clearing secretions
• Protecting the comatose pt. from aspiration
• Compromise from strictures from circumferetial
  chest burns

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Primary Survey--Circulation

• Burn victims have incr. capillary permeability in
  all burned areas resulting in an intravascular
  fluid shift into interstitial space
• Results are
• Hyponatremia
• Hypoprotienemia
• Interstitial edema

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Circulation

• Much confusion regarding fluid replacement
  guidelines!!
• All burn victims require large volumes of
  Na-containing fluid because of tissue edema
• Up to ½ of infused crystalloid lost to
  interstitial space
• Peak of 3rd spacing occurs at 6-12 hrs postburn
  as the capillary barrier begins to regain its
  integrity
• Delay in resuscitation can incr. fluid
  requirements by 30

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Circulation

• Hypertonic solutions
• 180-300 meq Na/L
• Mobilize intracelluler fluids into vascular space
  by incr. the osmotic gradient
• Should not allow Na.160 meq/dl

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Circulation

• Benefit of LR vs. NS for resuscitation
• LR lower Na and higher pH
• Closer to physiologic levels
• Metabolized lactate has a buffering effect on met
  acidosis associated with burns
• Plasmalyte is more closely physiologic, but incr.
  

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Circulation

• Parkland formula for fluid resuscitation
• 4 ml/kg x BSA 24 hour burn fluids
• ½ in fist 8 hrs postburn
• ½ in next 16 hrs

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Circulation

• Colloidal solutions
• Albumin
• Plasma protein that contribute to oncotic
  pressure
• 50 remains intravascular as opposed to 20-30
  crystalloid
• After 24 hrs, can use to test capillary leak
• If incr. U/O, some resolution of capillary leak
• Give 0.5-1 ml/kg per age burn
• Complications
• Pulmonary edema
• Renal dysfunction secondary to decr. GFR

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Circulation

• Dextran 40
• Polymerized, high MW glucose chain
• Twice oncotic pressure of albumin
• Incr. microcirculatory flowreduces RBC
  aggregation
• Decr. Edema formation in nonburned tissue
• Complications
• When stopped, rapid loss of fluid back into the
  interstitium if capillary leak present

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Circulation

• Pediatric considerations
• Proportionately higher BSAlarge head and small
  legs
• Higher weight- based resuscitation values as well
  as maintenance requirements.
• Parkland maintenance
• Titrate fluid to 1cc/kg/hr in kids

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Circulation

• Pediatric considerations
• Kids have low glycogen storesmay result in life
  threatening hypoglycemia
• Change from LR to D5LR after initial
  resuscitation
• Accu checks Q 4-6 during hypermetabolic state
• Venous access may be difficult
• Saphaneous vein cutdown or interosseous line

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Circulation

• Over resuscitation
• Results in
• Pulmonary edema
• 3rd spacing of tissues of chestescharotomies
• Prolonged ventilation
• Source of morbiditymonitor U/O closely
• Burns of lt15-20 w/o inhalation injury
• Lacks systemic inflammatory response
• Can rehydrate orally

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Secondary Survey

• IV access
• Lg. boreaway from burn site
• Swelling can dislodge IV
• Consider central linemay need U/S to help
  visualize IJ
• Femoral line not recommendedincr. infection

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Secondary Survey

• Foley to monitor fluid resuscitation
• NG/OG to decompress stomach
• Consider enteral tube feed
• Evaluate peripheral pulses
• Initially lowunder resuscitation
• Latermay below from compartment syndrome
• Low threshold for escharotomies or fasciotomies

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Secondary Survey

• Vital signs
• HR and BP difficult to interpret secondary
  hypermetabolic state
• Incr. catecholamines can support BP in spite of
  under resuscitation
• Art line may not be useful secondary to vasospasm
  from incr. catechols
• BP cuff limited B/C of peripheral edema
• Incr. HR may be from pain/anxiety or fluid
  depletion
• Therefore, following trend more useful than
  single reading

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Secondary Survey

• Anesthesia considerations
• Airway management
• Same or burn pt. who has not sustained inhalation
  injury
• Face and neck contractures awake intubation
• ATB cream on face may make mask application
  difficult

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Secondary Survey

• Pharmacology
• Potency of induction agents unchangedselection
  based on CV status preop
• Suxxcan cause incr. K related to incr. ACH
  receptors
• Avoid 8-10 hrs postburn until all grafts
  completely healed
• Treatment for incr. KCa, NaHCO3, hyperventilate,
  glucose/insulin

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Secondary Survey

• Pharmacologycontd
• Burn gt40 BSANDMR incr. 2-5x
• Incr. ACH receptors?
• Anticurare effect of plasma of burn pt.?
• Benzosrapid redistribution from brain to other
  tissues from hypermetabolic state-- decr.
  Efficacy
• Narcsno change in effecthowever, pt. rapidly
  develops tolerance
• Gasesused safely without change in efficacy

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Questions
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Questions
Ed Alexander, MAJ