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ENT anaesthesia

Created: 27/6/2006
Updated: 11/1/2007
 

Management of airway fire in laser microlaryngoscopy. How can this be avoided?


Laser microlaryngoscopy

  • High energy laser (CO2 or Nd-YAG) used along side the ETT
  • 0.5%-1.5% incidence of airway fire
  • Usually laser igniting ETT or swabs

Minimizing risk 

  • Surgeon
    • Control of laser direction and operation
    • Non-reflective instruments
    • Moistened swabs
    • Copious sterile water on setup
    • Fire drill should be agreed or rehearsed
  • Choice of ETT
    • Metal tube: Mallinkrodt “Laser Flex”
    • Metal coated silicone tube: Xomed “Laser Shield”
    • Metal tape coating on regular tube
      • Flammability silicone < rubber < PVC
      • Toxic debris silicone > PVC > rubber
    • Cuff is still vulnerable
      • Fill with saline ± methylene blue
      • Second cuff on Laser Flex
      • Distal placement of cuff (out of sight)
      • ?Place moist swabs on wires above cuff
    • Metal can be ignited or cut by Nd-YAG laser
    • Consider jet ventilation or oscillator
  • Airway gases
    • Minimize use of oxidant gases
      • Minimal required FiO2
      • No N2O
      • Helium retards ignition
    • Air available for ventilation in case of fire
  • Maintenance
    • Immobility required: deep anaesthesia or paralysis
    • High level of vigilance for fire
    • Good communication with surgeon

Managing fire

  • Remove source of fire and extinguish with water
  • Stop ventilation, turn off O2
  • Mask ventilate with air, then 100% O2 once fire is extinguished
  • Laryngoscopy and rigid bronchoscopy to remove debris
  • Lavage and fibreoptic bronchoscopy if indicated by airway injury
  • Common pattern is worst injury at the surgical site and little distal injury
  • If severe injury
    • Maintain ventilation
    • Consider low tracheostomy
    • IV corticosteroids may be helpful
    • CXR, ABG with co-oximetry for smoke inhalation assessment

Outline management of anaesthesia for resection of pharyngeal pouch

  • Surgery
    • Elective, moderate risk
    • High risk of aspiration
    • Close to major structures in neck
  • Assessment
    • Routine plus
    • History
      • Dysphagia, regurgitation and aspiration of food
        • Positional or on waking
    • Examination
      • Complications of lesion
        • Malnutrition, pneumonia
    • Investigations
      • Imaging of pouch: contrast studies, CT
  • Preoperative
    • Premedication to reduce aspiration risk: H2 blocker
  • Monitoring
    • Routine plus
    • Arterial line, CVC
    • Epidural if thoracic incision
  • Induction
    • Rapid sequence induction with cricoid pressure
    • Pharynx may need to be suctioned
    • Avoid high-pressure mask ventilation
      • Risks distension ± rupture of pouch
    • Consider cervical plexus block if neck incision
  • Maintenance
    • Usually supine with head turned to side
    • If lateral, increased risk of pressure areas
    • No nasogastric before surgery
      • May pass into pouch
  • Emergence
    • Aim for extubation when awake
    • Usually do not require HDU care

Local anaesthetic for tonsillectomy

  • Anatomy
    • Tonsil innervated by branches of glossopharyngeal n. which runs along stylopharyngeus and anterior palatal arch
  • Technique
    • Initial topical anaesthesia to pharyngeal arches with lignocaine
    • Tongue depressed with spatula
    • Infiltration of posterior palatal arch, then anterior palatal arch (IX n.)
    • Tonsil grasped with forceps and drawn medially
    • Tonsillar attachment infiltrated
    • Careful aspiration at all points because of proximity of ICA
  • Local anaesthetic
    • Lignocaine 0.5% 10-15 ml each side

Kindly provided by Dr James Mitchell from his pharmacodynamics series


ArticleDate:20060627
SiteSection: Article
 

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