Burns- management and anesthetic considerations

Question 1

What are the phases seen after a burn injury?

What are the phases of treatment?

Answer 1

• Biphasic response
  
  • Burn shock develops 6-8 hours after injury
  • Hypermetabolic phase develops in several days to weeks
• Treatment in 3 phases:
  
  • 1) resuscitative
  • 2) debridement and grafting
  • 3) reconstructive

Question 2

What do the different organs/systems do during the early and later phases post burn injury? (table)

CV

urinary

GI

musculoskeletal

pulmonary

endocrine

immunologic

CNS

Answer 2

Question 3

Another table about the systemic response during the early phase vs the late phase.

CV

Pulm

renal

endocrine and metabolic

hepatic

hematologic

GI

neurologic

Answer 3

Question 4

What should you consider during initial airway assessment of a pt with burns?

Answer 4

• Consider liklihood of inhalation injury
• inspect the neck and oral cavity for overt issues
• Gold standard assessment: fiberoptic bronchoscopy
  
  • Chest x-ray is usually normal in early phase
• Early intubation when upper airway injury is suspected, do NOT wait for pt to decompensate

Question 5

Who is at risk for inhalation injury?

Answer 5

• Facial burns
• hoarseness
• evidence of smoke exposure
• other classical signs of inhalation injury

Question 6

What should you consider regarding airway management in a burn patient?

Answer 6

• Intubation will be easier if not delayed
• Awake, spontaneously breathing fiberoptic intubation if any airway abnormality is suspected
  
  • topical anesthesia plus hypnotic that preserves spontaneous ventilation (ketamine, dexmedetomidine)
  • use opioids and sedatives judiciously
• If there is no airway abnormality, RSI can be used, but NO SUCC after first 24 hours post injury
• Severe airway burns may require immediate surgical airway/trach
• Cuffed tubes are standard of care
• MUST have humidification–secretions are thick and tenacious, very likely to form mucous plug

Question 7

What is the initial management during the burn shock phase?

Answer 7

• This is a combination of distributive, hypovolemic, and cardiogenic shock
• Priorities: airway management and fluid resuscitation
• Fluid losses greatest in first 12 hours and stabilize at 24 hours
• Volume loss and edema
  
  • transudation of plasma proteins directly from wound bed
  • interstitial fluid shifts in unburned tissue secondary to capillary leak
• Crystalloids are fluid of choice in 1st 24 hours

Question 8

What can happen with over-resuscitation?

Answer 8

• over-resuscitation can lead to complicationsintraabdominal hypertension- is reversible
  
  • >12
• abdominal compartment syndrome- leads to organ damage
  
  • >20
• pleural and pericardial effusions
• pulmonary edema
• fasciotomy
• conversion of partial thickness to full thickness (think of the jackson burn zones)

Question 9

What is the Parkland fluid resuscitation formula?

Answer 9

• 4 ml/kg per percentage of TBSA burned in 1st 24 hours
  
  • half of calculated volume should be administered in first 8 hours
  • LR preferred

Question 10

What is the hypermetabolic phase?

Answer 10

• Develops over several days to weeks, changes can persist up to two years
• Caused by immense surge in catecholamines and corticosteroids (10-50x baseline)
• Persistent tachycardia, systemic hypertension, tachypnea, increased muscle protein degredation, insulin resistance, elevated core temp, liver dysfunction increased risk of infection
• Can lead to physical exhaustion and death without treatment

Question 11

What are the symptoms seen during hypermetabolic phase?

What are treatments?

Answer 11

• Symptoms
  
  • Persistent tachycardia
  • systemic hypertension
  • tachypnea
  • increased muscle protein degredation
  • insulin resistance
  • elevated core temp
  • liver dysfunction increased risk of infection
• Treatment:
  
  • early excision and grafting
  • warming strategies (burn or kept at 87-90 degrees)
  • nutritional support
  • insulin
  • beta blockers

Question 12

How is excision (escharotomies) and grafting done?

Answer 12

• Aggressively cut off dead tissue until they get to massive blood loss, then they lay epi soaked flaps over the bleeding area
  
  • Can have up to 2L blood loss in 15 minutes
• Surgery done every 2-3 days
• Early debridement preferred, often done in stages
  
  • started on 2nd day to 2nd week of unjury
• Blood loss can be significant.

Question 13

What are indications to suspend excision surgery?

Answer 13

• 20% of BSA excised (may extend this to larger area if pt is stable)
• time length of 2-3 hours
• temperature drop to 35 C
• blood loss requiring 10 units or mor PRBCs

Question 14

What should be included in preoperative evaluation?

(9)

Answer 14

• Age, weight
• Pre-existing co-morbidities
• review labs including acid/base
• airway assessment, vent settings
• TBSA burned, note inhalation injury and co-existing trauma
• Mechanism of injury (flame, explosion, chemical, electrical, scald) and time since injury
• Vascular access and adequacy of resuscitation (current fluid requirements, UOP, vasopressor requirements)
• Surgical plan
• review previous anesthetic records

Question 15

How long should burn patients be NPO?

Answer 15

• NPO after midnight is NOT appropriate for these patients!
• Adequate caloric intake is critical
• No need to d/c enteral feeds for intubated patient
  
  • unintubated patients can have feeds continue up to 4 hours before surgery
  • Once in OR, decompress NG tube/check residuals
• Parenteral feeds should be continued intraoperatively and do not use the specific line for them
• For procedure with unprotected airway like placing a trach, should adhere to more standard NPO guidelines

Question 16

How should you set up pre-operatively for a burn patient?

Answer 16

Question 17

What should you consider during induction of a burn patient?

Answer 17

• Need all standard monitors, may need to have ekg leads stapled to pt
• It is rare to see burn pt in first 24 hours, if you do, reduce dosage of induction agents d/t shock
• NO SUCC AFTER FIRST 24 HOURS
• Expect resistance to NDMB, will need higher/more frequent dosing
• May be unable to take off vent d/t required settings, if so , use TIVA

Question 18

What should you consider intraoperatively for a pt with burns?

(7)

Answer 18

• Arterial blood pressure required if >20-30% TBSA involved
• Accurate temperature monitoring essential/avoid hypothermia/actively warm patient and room
• Continue ICU infusions, including narcotics and O2 during transport
• Ensure ETT securement is infallible
  
  • may need to wire to teeth or screw into mandible
• Blood loss can be rapid and tremendous- need adequate product immediately available and checked in room
• Anticipate use of epi-soaked gauze–may see systemic effects
• pain control

Question 19

Why are the effects of neuromuscular blockers different in patients who have burns?

Answer 19

• Proliferation of extrajunctional nicotinic acetylcholine receptors
  
  • causes resistance to nondepolarizing muscle relaxants
  • increased sensitivity to depolarizing muscle relaxants (succ)
• Succ >24 hours post injury is PROHIBITED
  
  • potentially lethal hyperkalemic response
  • may persist for up to 18 months post injury
• Resistance to non-depolarizing muscle relaxants may develop within a week of burn injury
  
  • persist up to 1 year
  • 2-5x greater dose
  • Rocuronium in large doses up to 1.2 mg/kg can be used for RSI
  • Resistance does not prolong recovery times or alter efficacy of reversal agents

Question 20

What should you consider with ventilator management of a burn patient?

Answer 20

• Anticipate pulmonary compromise
  
  • RAD, laryngospasm, bronchospasm, ventilation-perfusion mismatch, decrease in pulmonary compliance , PNA, ALI, ARDS
• may need high FiO2 and frequent suctioning
• Lung protective ventilation
  
  • target TV 4-8 ml/kg
  • plateau pressure = 30 cm H2O
  • permissive hypercapnia up to pH of 7.2
• HFOV- may require TIVA