Nitrous oxide

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  • For minimal sedation or anxiolysis
  • It may be used as an adjunct with local anesthetics for more painful procedures


  • Older than 4 years and/or weighing greater than 15 kg
  • ASA Class 1 or 2
  • Sole Nitrous Oxide use examples include:
    • Peripheral or Central IV placement
    • Urinary catheter insertion
    • Intramuscular injections
    • Joint aspiration or injection
    • Lumbar puncture
    • Laceration repair
    • Abscess incision and drainage
    • Nail removal
    • Wound packing or dressing change
    • Foreign body removal
  • Nitrous Oxide + opioid or benzodiazepine examples include (smaller dosages should be used initially and titrated PRN)
    • Lumbar puncture
    • Laceration repair
    • Abscess incision and drainage
    • Foreign body removal
    • Simple or minimally displaced fracture reduction


  • Should NOT be coadministered with
  • Age less than 4 years and/or weight less than 15 kg
  • ASA Class 3 or above
  • Closed head injury, recent craniotomy, altered level of consciousness or suspicion of elevated intracranial pressure
  • Penetrating globe injury or recent eye surgery
  • Complex upper respiratory infection (obstructive sinusitis, bullous otitis media)
  • Maxillofacial injuries
  • Acute asthma, bullous emphysema or pneumonia
  • Pneumothorax or chest trauma
  • Pulmonary hypertension
  • Congenital heart disease
  • Bowel obstruction or ileus
  • Recent SCUBA diving, barotrauma or decompression illness
  • Pregnancy


  • Pre-sedation establishment of an IV is not required
  • General monitoring procedures shall be followed
  • Nitrous oxide administration should be limited to 30 minutes
  • Administer 100% oxygen for 2-5 minutes after discontinuing nitrous oxide or if nitrous oxide / oxygen administration is interrupted for > 30 seconds


  • Asphyxia, if oxygen is not given with the gas
    • Headache
    • Dizziness
    • Confusion
    • Syncope
    • Seizures
  • Chronic toxicity results from B12 inactivation
    • Megaloblastic anemia
    • Thrombocytopenia
    • Peripheral Neuropathy