Anesthesia for Burns Thermal Injuries by zbk75252

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									      Anesthesia
          for
Burns & Thermal Injuries




    Brad Metzenbacher
      Jeremy Orwin
Thermal Injury
               Overview
•   Anatomy & Physiology
•   Pathophysiology
•   Pharmacology
•   Anesthetic Technique & Management
•   Management of Complications
Anatomy & Physiology
Anatomy & Physiology of the Skin
       Functions of the Skin
• Largest organ of body
  – Sensory organ
  – Thermoregulation
  – Prevents the loss of body fluids
  – Protective barrier against microorganisms
Structures of the Airway
Pathophysiology
     Types of Thermal Injuries
• Thermal
     • Flame
     • Steam
     • Scald
• Electrical
• Chemical
• Inhalation
             Thermal Injuries
•   1st Degree
•   2nd Degree
•   3rd Degree
•   4th Degree
•   Frostbite
Structure of the Skin
     Classification of Burn Depth
            “First-Degree”
• First–degree
  • Superficial (sunburn)
  • Erythema, pain,
    absence of blisters
  • Consists of epidermal
    damage alone


• Heals within 3 to 6
  days
     Classification of Burn Depth
          “Second-Degree”
• Second-degree
  • Involves:
  • Entire epidermal layer
  • Part of underlying
    dermis
  • Mottled and red,
    painful, swelling and
    blisters

• Healing in 10 to 21
  days
    Classification of Burn Depth
         “Second-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
Classification of Burn Depth
     “Second-Degree”
    Classification of Burn Depth
            Third-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)
Classification of Burn Depth
        Third-Degree
   Classification of Burn Depth
          Fourth-Degree
• Fourth-degree
 • Full-thickness
 • Extending into muscle, tendons or
   bones
 • Typically involves appendage
 • Black and dry
 • No pain
                 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
               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
             Inhalation Burns
• Smoke inhalation
• Heat inhalation injury
• Asphyxiation
• Carbon monoxide
  (CO) poisoning
• Toxic gas inhalation
    Carbon Monoxide Poisoning
• CO combines w/ Hgb  Carboxyhemoglobin (COHb)
   – 200 x’s 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
                     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
Stages of Thermal Injuries

      1st Stage – Edema

     2nd Stage – Diuresis
           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
                 1st Stage Con’t
• Burns >30% 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
            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
            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
            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
          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
          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
          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
            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
           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
             Impact on Systems
• Respiratory System Con’t
   – 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
Estimation of Burned Area
                 Rule of 9’s
•   Head and neck…9%
•   Each arm………..9%
•   Each leg………..18%
•   Anterior trunk…..18%
•   Posterior trunk…18%
•   Perineum………...1%
         Lund and Browder
• Designed
  for children
• Larger heads
• Adjustments
  based on growth
Pharmacology
            Induction Medications
      Hemodynamics                             Medication
             Stable                          Propofol / STP
        Questionable                             Ketamine
           Unstable                             Etomidate
Remember – medications may be more potent and have a prolonged effect in
the burn patient.
           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 patient’s tend to
  be resistant to the effects of non-
  depolarizing muscle relaxants
     • May need 2-5 x’s the normal dose!!!
Anesthetic Technique &
     Management
 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
       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
 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
 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
 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
Management of
Complications
           General Concerns
•   Compromised Airway
•   Hypovolemia
•   Compromised Vascular Access
•   Interaction of Anesthetic Agents
•   Pain
            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
            Inhalation Injury
• Supportive Care
  – Maintain oxygenation
  – Manage bronchospasms
  – Fluid replacement
  – Pulmonary toilet
  – Intubation / tracheostomy
    • Low volume, high PEEP
              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
        Common Operations
• Decompression procedures
     • escharotomies & fasciotomies
• Burn excision & skin grafting
• Reconstruction operations
• Supportive procedures
     • tracheostomy, gastrostomy, vascular access
               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.
                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.
 Review – Anesthetic Management
• Preop Meds                           • Temperature Regulation
   – Provide adequate analgesia           – Increase ambient temperature
   – Fluids                               – Warm IV fluids
• Establish Adequate Vascular          • Anesthetic Drugs
  Access                                  – Include opioids
   – Consider Invasive Monitoring         – Consider effects of increased
• Airway Management                         circulating catecholamines
   – Consider Alternatives to Direct   • Muscle Relaxants
     Laryngoscopy                         – Avoid Anectine
       • Awake FOB                        – Anticipate resistance to
• Ventilation                               nondepolarizing muscle
   – Increased minute ventilation           relaxants
       • increased metabolic rate      • Postoperative
• Fluids & Blood                          – Anticipate increased analgesic
   – Anticipate rapid, large blood          requirements
     loss
   – Parkland Formula
                 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.
         Case Presentation
• Anesthetic considerations
  – Health concerns
  – Potential problems
  – Fluid replacement
  – Areas burned
         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 2-5x’s normal
      dose
    • Avoid Des – more irritating to airway
    • Possibly use TIVA technique – drugs?
          Case Presentation
• Health issues
  – Fluid replacement
    • Parkland formula – 4 mL x 125 kg x 45% burned
       – 22,500 mL’s – replace 1st half over 8 hours, 2nd half over
         next 16 hours
  – Comorbidities
    • Hypertension
    • Diabetes
    • Etoh consumption
Questions?
                      Questions for quiz
1.   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%

2.   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

3.   Which relaxant should be avoided 24 hours following burn injury and why?
         Succinocholine, severe hyperkalemia

4.   What are the four types of burns a patient can receive?
        Thermal, Chemical, Electrical, Inhalation

5.   What is the major concern with anyone with facial burns?
        Damage to airway structures creating a difficult intubation scenario

								
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