Anesthesia for Burns

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Anesthesia for Burns Thermal Injuries

• Brad Metzenbacher
• Jeremy Orwin

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Thermal Injury
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Overview

• Anatomy Physiology
• Pathophysiology
• Pharmacology
• Anesthetic Technique Management
• Management of Complications

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Anatomy Physiology
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Anatomy Physiology of the Skin
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Functions of the Skin

• Largest organ of body
• Sensory organ
• Thermoregulation
• Prevents the loss of body fluids
• Protective barrier against microorganisms

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Structures of the Airway
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Pathophysiology
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Types of Thermal Injuries

• Thermal
• Flame
• Steam
• Scald
• Electrical
• Chemical
• Inhalation

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Thermal Injuries

• 1st Degree
• 2nd Degree
• 3rd Degree
• 4th Degree
• Frostbite

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Structure of the Skin
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Classification of Burn DepthFirst-Degree

• Firstdegree
• Superficial (sunburn)
• Erythema, pain, absence of blisters
• Consists of epidermal damage alone
• Heals within 3 to 6 days

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Classification of Burn DepthSecond-Degree

• Second-degree
• Involves
• Entire epidermal layer
• Part of underlying dermis
• Mottled and red, painful, swelling and blisters
• Healing in 10 to 21 days

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Classification of Burn DepthSecond-Degree

• Superficial partial-thickness
• Usually quite painful
• Erythemetous with blebs and bullae
• Even air motion across skin hurts
• Deep partial-thickness
• Sensation impaired to a variable degree

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Classification of Burn DepthSecond-Degree
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Classification of Burn DepthThird-Degree

• Third-degree (Full thickness)
• Destruction of all epidermal and dermal elements
• Burn into subcutaneous fat or deeper
• Skin is charred and leathery (woody)
• Pearly-white sheen / waxy
• Generally not painful (nerve endings are dead)

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Classification of Burn DepthThird-Degree
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Classification of Burn DepthFourth-Degree

• Fourth-degree
• Full-thickness
• Extending into muscle, tendons or bones
• Typically involves appendage
• Black and dry
• No pain

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Electrical Burns

• Similar to thermal burns
• True extent of the damage is often hidden
• Entry / exit wound
• best ? worst conductors nerve, blood, muscle,
  skin, tendon, fat, bone
• Clinical Findings
• Hyperkalemia
• Acidosis
• Myoglobinuria is common
• Maintain high u/o to avoid renal damage
• Peripheral neuropathies or spinal cord deficits
• Cataract formation
• Cardiac dysrhythmias up to 48o post injury

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Chemical Burns

• Caused by strong acid or alkaline solution
• Damage continues until the substance is removed
  or neutralized
• May take time to take effect may continue to
  penetrate 24-48hrs
• Full-thickness burns appear superficial
• Flush with copious amounts of water
• Specific Antidotes
• Hydrofluoric Acid ? 10 Calcium Gluconate
• Phenols ? polyethylene glycol methylated
  spirits
• Phosphorus ? 1 copper sulfate identifies
  residual phosphorus

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Inhalation Burns

• Smoke inhalation
• Heat inhalation injury
• Asphyxiation
• Carbon monoxide(CO) poisoning
• Toxic gas inhalation

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Carbon Monoxide Poisoning

• CO combines w/ Hgb ? Carboxyhemoglobin (COHb)
• 200 xs more affinity for Hgb
• Direct myocardial depression
• S S
• Headache, irritibility
• Respiratory failure, myocardial ischemia
• Seizures, coma, death
• Treatment 100 O2 (reduces CO half-life from
  4hrs to 40min)
• SpO2 will read falsely high
• ABGs must have co-oximetry to determine true O2
  saturation

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Frostbite

• Local freezing of tissue
• Ice formation in the extracellular space
• Appears waxy / white
• Extent of damage may be hidden for days to weeks
• Numbness Pain (upon thawing)
• Upon thawing
• Severe hyperemia, edema, blistering
• RBC Platelet dumping circulatory stasis /
  ischemia (gangrene)
• Treatment
• Rapid re-warming decreases extent of the damage
• Emersion in warm water

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Stages of Thermal Injuries

• 1st Stage Edema
• 2nd Stage Diuresis

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1st Stage Edema

• First 24 hours
• Fluid leak vascular space ? interstitial space
• ? osmotic pressure
• ? capillary permeability
• Vasoactive substances released
• ? interstitial edema and intravascular
  hypovolemia occurs

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1st Stage Cont

• Burns gt30 BSA cause capillary changes in both
  burned and non-burned tissue
• Burned tissue edema
• Direct thermal injury to endothelial cells and ?
  burn tissue osmolarity
• Non-burn tissue edema
• Severe hypoproteinemia
• Small wound
• Edema greatest 8-12 hrs post injury
• Large wound
• Edema greatest 18-24 hrs post injury

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2nd Stage Diuresis

• 24-36 hours after burn, fluid and electrolytes
  begin to remobilize back into intravascular space
• Capillary seal reestablishes
• Diuresis occurs due to ? GFR in response to ?
  intravascular volume
• May see hypernatremia and hypokalemia
• Cardiac output may ? 200-300 normal
• ? O2 consumption

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Impact on Systems

• Immune System
• Alters immune cells ability to function
• ? killing power of neutrophils
• Macrophages and lymphocytes do not work well
• Hematologic System
• Destruction of RBCs
• Hemoglobinuria
• ? Hgb level ? viscosity
• ? WBC level
• Coagulation altered

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Impact on Systems

• Cellular Response
• ? tissue oxygen tension
• Na and H2O shift into cell ? intracellular
  swelling
• Possible cell death
• ? K level intravascularly
• ? O2 level
• Anaerobic metabolism begins
• ? Lactic acid levels
• Metabolic acidosis occurs

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Impact on Systems

• Endocrine System
• Massive release of catecholamines, glucagon,
  ACTH, ADH, Renin, Angiotensin, Aldosterone
• Hyperglycemia
• Neurological System
• ? cerebral perfusion
• Cerebral edema occurs from Na shifts
• Carbon monoxide or associated head injury may
  cause neuro changes

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Impact on Systems

• GI System
• Slow peristalsis and possible ileus
• ? HCL acid secretion from stress response
• Narcotics for pain management further slow
  peristalsis
• Hepatic System
• Decreased hepatic synthesis
• Decreased metabolic function

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Impact on Systems

• Renal System
• ?RBF GFR
• Activation of RAS
• Release of ADH
• retain water Na
• lose of K, Ca, Mg
• ARF
• Acute Tubular Necrosis 2o hemoglobinuria
  myoglobinuria d/t hemolysis tissue necrosis
• Maintain high u/o (2ml/kg/hr) w/ fluids / osmotic
  diuretics

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Impact on Systems

• CV System (first 24 hrs)
• Activation of CNS system and catecholamine
  release
• Tachycardia
• Vasoconstriction
• During early phase
• Classic S/S of compensated shock
• Dramatic decrease in cardiac output
• Volume loss and decreased venous return
• ? preload
• ? cardiac filling pressure
• ? CVP and PCWP
• After 24hrs increased blood flow to tissues, HTN

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Impact on Systems

• Respiratory System
• Upper airway injury
• Involves all of airway to level of true vocal
  cords
• Initially due to inflammation from heat of
  inspired smoke
• Exacerbated by accumulation of excess
  interstitial fluid
• Major airway injuries
• Involves trachea and bronchi
• Parenchymal injury
• Involves entire respiratory tract down to, and
  including, alveolar membrane
• Commonly lethal within first few hours after
  injury due to profound bronchospasms and hypoxia

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Impact on Systems

• Respiratory System Cont
• 0-24hrs
• Edema
• Obstruction
• Carbon Monoxide Poisoning
• 2-5 Days
• May develop ARDS
• Signs Symptoms
• Stridor / Hoarseness / Facial burns /
  Singed nasal hairs / Carbonaceous sputum /
  Impaired level of consciousness
• S/S of deteriorating ABGs increasing
  respiratory distress

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Estimation of Burned Area
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Rule of 9s

• Head and neck9
• Each arm..9
• Each leg..18
• Anterior trunk..18
• Posterior trunk18
• Perineum...1

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Lund and Browder

• Designed for children
• Larger heads
• Adjustments based on growth

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Pharmacology
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Induction Medications
Remember medications may be more potent and
have a prolonged effect in the burn patient.
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Muscle Relaxants

• Anectine safe in the 1st 24hrs (afterwhich
  hyperkalemia may be a problem up to a year or the
  burn is healed)
• Non-depolarizers burn patients tend to be
  resistant to the effects of non-depolarizing
  muscle relaxants
• May need 2-5 xs the normal dose!!!

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Anesthetic Technique Management
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Preoperative Evaluation Testing

• Initial evaluation of the burn patient
• Time of the injury
• Type (electrical / chemical), depth, extent of
  burn
• Airway / pulmonary damage
• Age, allergies, medications
• Associated trauma
• Co-existing medical conditions
• Anesthetic history

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Preoperative Testing

• Diagnostic Testing
• ABG (w/ co-oximetry) ? acid-base balance
• Electrolytes ? imbalances (hyperkalemia)
• Serial Hct ? ongoing blood loss or erythrocyte
  destruction / volume status
• Coagulation Profile ? rule out a bleeding
  diathesis
• Urine Myoglobin (electrical injuries or pigmented
  u/o)
• CXR

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Anesthetic Technique Management

• Preop Meds
• Provide adequate analgesia
• Fluids
• Establish Adequate Vascular Access
• Consider Invasive Monitoring
• Airway Management
• Consider Alternatives to Direct Laryngoscopy
• Awake FOB

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Anesthetic Technique Management

• Ventilation
• Increased minute ventilation
• increased metabolic rate
• Fluids Blood
• Anticipate rapid, large blood loss
• Evaluate coagulation status
• Temperature Regulation
• Increase ambient temperature
• Warm IV fluids

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Anesthetic Technique Management

• Anesthetic Drugs
• Include opioids
• Consider effects of increased circulating
  catecholamines
• Muscle Relaxants
• Avoid Anectine
• Anticipate resistance to nondepolarizing muscle
  relaxants
• Postoperative
• Anticipate increased analgesic requirements

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Management of Complications
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General Concerns

• Compromised Airway
• Hypovolemia
• Compromised Vascular Access
• Interaction of Anesthetic Agents
• Pain

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Thermal Injuries

• General Management
• Stop the burning
• Supportive care
• Oxygen (intubation)
• Fluid replacement
• Electrolyte management
• Escharotomies / Fasciotomies
• Wear isolation materials with patient contact
• Do NOT institute broad spectrum antibiotics

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Inhalation Injury

• Supportive Care
• Maintain oxygenation
• Manage bronchospasms
• Fluid replacement
• Pulmonary toilet
• Intubation / tracheostomy
• Low volume, high PEEP

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Fluid Resuscitation

• Parkland formula
• 4cc X weight X burn
• ½ volume in first 8 hours
• Second ½ over last 16 hours
• Brooke formula
• 2cc X weight X burn
• ½ volume in first 8 hours
• Second ½ over last 16 hours
• Daily maintenance fluids

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Common Operations

• Decompression procedures
• escharotomies fasciotomies
• Burn excision skin grafting
• Reconstruction operations
• Supportive procedures
• tracheostomy, gastrostomy, vascular access

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Escharotomy

• A surgical incision of the eschar and superficial
  fascia in order to permit the cut edges to
  separate and restore blood flow to unburned
  tissue distal to the eschar.
• Circumferential burns (impede ventilation)
• Compartment syndrome (impede perfusion)
• Can be performed at the bedside / ED.

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Fasciotomy

• The fascia is thin connective tissue covering, or
  separating, the muscles and internal organs of
  the body.
• Usually done by a surgeon under general or
  regional anesthesia.
• An incision is made in the skin, and a small area
  of fascia is removed where it will best relieve
  pressure. Then the incision is closed.

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Review Anesthetic Management

• Preop Meds
• Provide adequate analgesia
• Fluids
• Establish Adequate Vascular Access
• Consider Invasive Monitoring
• Airway Management
• Consider Alternatives to Direct Laryngoscopy
• Awake FOB
• Ventilation
• Increased minute ventilation
• increased metabolic rate
• Fluids Blood
• Anticipate rapid, large blood loss
• Parkland Formula

• Temperature Regulation
• Increase ambient temperature
• Warm IV fluids
• Anesthetic Drugs
• Include opioids
• Consider effects of increased circulating
  catecholamines
• Muscle Relaxants
• Avoid Anectine
• Anticipate resistance to nondepolarizing muscle
  relaxants
• Postoperative
• Anticipate increased analgesic requirements

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Case Presentation

• 30 y/o male coming back to O.R. the day following
  initial injury for debridement of 2nd and 3rd
  degree burns of chest, arms, and face.
• History Patient was outdoors lighting barbeque.
  Coals were not lighting as anticipated so patient
  was spraying them with lighter fluid.
• Flames flashed back up stream of lighter fluid
  and in a panic the patient sprayed himself.
• He has been maintaining his own airway, however
  you notice that he is having stridor and oxygen
  saturations have slowly decreased over last 4
  hours.
• Additional medical history include mild
  hypertension - for which patient was on
  metoprolol 100 mg daily, borderline diabetes,
  obesity 125 kg, daily ETOH consumption of a 6
  pack of beer.

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Case Presentation

• Anesthetic considerations
• Health concerns
• Potential problems
• Fluid replacement
• Areas burned

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Case Presentation

• Anesthetic concerns
• New respiratory concern how should we manage
  this?
• Awake FOB
• What drugs should we use potential problems?
• No succs consider Roc/Nimbex at 2-5xs normal
  dose
• Avoid Des more irritating to airway
• Possibly use TIVA technique drugs?

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Case Presentation

• Health issues
• Fluid replacement
• Parkland formula 4 mL x 125 kg x 45 burned
• 22,500 mLs replace 1st half over 8 hours, 2nd
  half over next 16 hours
• Comorbidities
• Hypertension
• Diabetes
• Etoh consumption

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Questions?
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Questions for quiz

• What is the percentage of burned area for a 7 y/o
  with burns on the left side of the body, front
  and back?
• A) 34
• B) 43
• C) 29
• D) 51
• How much fluid should you give the first 8 hours
  to a 70 kg person burned over 25 of their body?
• A) 3000 mL
• B) 4000 mL
• C) 7000 mL
• D) 3500 mL
• Which relaxant should be avoided 24 hours
  following burn injury and why?
• Succinocholine, severe hyperkalemia
• What are the four types of burns a patient can
  receive?
• Thermal, Chemical, Electrical, Inhalation
• What is the major concern with anyone with facial
  burns?