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Nitrogen Narcosis

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Other Names

  • Nitrogen Narcosis
  • Rapture of the Deep (as described by Jacques Cousteau)
  • Depth Intoxication
  • Narks
  • Inert gas narcosis
  • Martini effect


  • This page refers to the toxic effects of breathing nitrogen-containing gases at depth


  • First described by Albert Behnke in 1935[1]
    • Rare at depths less than 30 meters (100 ft) unless breathing non-standard air mixtures


  • Responsible for up to 9% of diving deaths[2]


  • General
    • Occurs as a result of inhalation of compressed nitrogen at depth
    • Generally manifests as intoxication and euphoria
    • Impaired judgement and euphoria can produce dangerous circumstances
    • The condition is reversible and resolves rapidly with ascent


  • Develops between 3-4ATM (99-132 feet)[1]
    • Sensitive divers may develop symptoms at 3 ATM
    • Other divers may not be affected until 6 ATM
  • Divers can develop "tolerance"[3]
    • Similar to alcohol consumption
    • Impairment remains despite tolerance
  • Other inert gases
    • Almost universally occurs with nitrogen
    • However, can also occur when other inert gases, such as neon, argon, krypton, and xenon
    • Note that helium does not cause inert gas narcosis, which is why it is used in deep diving

Risk Factors

  • Diving related[4]
    • Exertion during dive
    • Cold conditions
    • Alcohol consumption before dive
    • Diving to greater depth
    • Fatigue before diving
    • Apprehension before or during a dive

Differential Diagnosis

Differential Diagnosis Dive Medicine

Clinical Features

  • History
    • Onset is typically insidious
    • Early: euphoria, false sense of security, impaired judgement, diminished reaction times
    • Later: impaired concentration and memory, hallucinations, parasthesia
    • Final: lethargy, loss of consciousness (typically occurs at depths of 10-13 ATM or 333 to 429 feet)
  • Physical Exam
    • Symptoms typically resolve upon surfacing
    • Exam is often normal


  • Diagnosis is primarily clinical


  • There is no classification system


  • Ascent
    • Reduces the partial pressure of dissolved nitrogen
    • Symptoms will reverse within minutes of ascension to a shallower depth[5]
    • Typically no long term effects from this
    • If symptoms persist after ascent, consider broader differential diagnosis
  • Hospitalization is typically not required


  • See: Dive Medicine Prevention
  • Preventing nitrogen narcosis
    • Avoid diving to depths >100 feet
    • Use nitrogen free gas mixture (e.g. heliox)
    • Use mixture with reduced nitrogen content (e.g. Trimix = helium-nitrogen-oxygen)
    • Frequent check on diving companions

Rehab and Return to Play


  • Not applicable

Return to Play/ Work

Complications and Prognosis


  • Prognosis is very favorable if divers ascend upon recognition of the disease


  • Death/ drowning
    • Occurs due to impaired judgement at depth

See Also


  1. 1.0 1.1 Grover CA, Grover DH. Albert Behnke: nitrogen narcosis. J Emerg Med. 2014 Feb;46(2):225-7.
  2. Levett, D. Z. H., and I. L. Millar. "Bubble trouble: a review of diving physiology and disease." Postgraduate medical journal 84.997 (2008): 571-578.
  3. Unsworth, I. P. "Inert gas narcosis: An introduction." Postgraduate medical journal 42.488 (1966): 378.
  4. Spira, Alan. "Diving and marine medicine review part II: diving diseases." Journal of travel medicine 6.3 (1999): 180.
  5. Melamed, Yehuda, Avi Shupak, and Haim Bitterman. "Medical problems associated with underwater diving." New England Journal of Medicine 326.1 (1992): 30-35.
Created by:
John Kiel on 30 June 2019 23:02:49
Last edited:
25 July 2022 20:48:56