II. Epidemiology

  1. Nitrous Abuse is common among (esp. dentists, Anesthesia professionals, as well as teens)

III. Preparations: Sources

  1. Nitrous Oxide is widely used in dental Anesthesia
  2. Used in food industry to generate foam
  3. Sold illegaly in 10 ml steel bulbs (Whippets)
    1. Abused by puncturing pressurized bulbs and releasing Nitrous Oxide into a balloon
    2. Gas is then inhaled from balloon

IV. Pathophysiology

  1. Acute use
    1. Stimulates Dopamine, GABA and NMDA receptors
    2. May stimulate endogenous Opioid release
  2. Chronic use
    1. Vitamin B12 oxidation and inactivation
      1. Vitamin B12 is a Cofactor in Methionine synthase
    2. Decreases production of Methionine and Tetrahydrofolate
      1. Results in Bone Marrow suppression, decreased DNA synthesis and myelin production
      2. Also impacts spinal cord degeneration (see below)

V. Pharmacokinetics

  1. Peak effect: 30 seconds
  2. Resolution: 5 minutes
  3. More than 90% of Nitrous Oxide is exhaled unchanged
  4. No significant toxic metabolites

VI. Symptoms: Desired Effects by Illicit Users

  1. Euphoria
  2. Dissociation
  3. Hallucinations
  4. Analgesia

VII. Labs

  1. Macrocytic Anemia
  2. Vitamin B12 Level decreased

VIII. Diagnostics

  1. Spinal MRI
    1. Central and dorsal spinal cord degeneration
  2. Nerve Conduction Studies
    1. Polyneuropathy

IX. Adverse Effects: Acute

  1. Hypoxia
  2. Nausea
  3. Light Headedness
  4. Trauma from Loss of Consciousness (i.e. falls)

X. Adverse Effects: Chronic

  1. Macrocytic Anemia
    1. Fatigue
    2. Weakness
    3. Syncope
  2. Neurologic effects (general)
    1. Delusions
    2. Unusual behavior
    3. Vitamin B12 Deficiency related effects
      1. Paresthesias
      2. Decreased proprioception
      3. Ataxia
      4. Hyperreflexia
      5. Urinary Incontinence
      6. Paralysis
  3. Nitrous Induced Subacute Combined Degeneration of the Spinal Cord
    1. Nitrous Oxide inhalation interferes with Vitamin B12 Metabolism
    2. Results in Vitamin B12 Deficiency with secondary long segmental changes involving the Posterior Columns
    3. See Pathophysiology as above

XI. Management

  1. Eliminate exposures
  2. Vitamin B12 Supplementation

XII. References

  1. Masom and Tomaszewksi (2019) Crit Dec Emerg Med 33(4):28

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