INDEX

    Decompression Sickness

    Environmental Injuries / Exposures

    Last Updated Feb 09, 2021
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    By Julian Marsden, Dave Zhu

    Context

    • Decompression sickness (DCS) occurs when a person breathing pressurized air rapidly goes from a high to lower pressure environment, facilitating the formation of bubbles in the tissues and/or vasculature.
    • DCS can occur in:
      • SCUBA divers.
      • Caisson workers (working in a pressurized container in an area under water).
      • Individuals flying at high altitude in an unpressurized aircraft, or sudden loss of cabin pressure.
      • Astronauts returning from spacewalks.
    • Signs and symptoms range from mild joint pain and localized cutaneous presentations to severe neurological changes, circulatory collapse, and death.
    • DCS may occur concurrently with other diving disorders such as arterial gas embolism, pneumothorax, drowning, or barotrauma.
    • Definitive treatment of DCS is prompt hyperbaric oxygen therapy, with delays leading to less successful outcomes (1).
    • Untreated severe DCS may result in permanent neurological deficits.

     

    2 Types of DCS exist:

    • Type 1 DCS
      • Mild symptoms.
      • Musculoskeletal: Joint pain, with extremities more commonly affected.
      • Cutaneous: Localized erythema and pruritus.
      • Lymphatic: Pain, lymphadenopathy, localized edema.
    • Type 2 DCS
      • Severe symptoms.
      • Neurologic: Paresthesia, ascending paralysis.
      • Vestibular: Vertigo, tinnitus, hearing loss.
      • Pulmonary: Cough, hemoptysis, dyspnea, substernal chest pain.
      • Cardiovascular collapse.

    Diagnostic Process

    Diagnosis is based on history and physical exam.

    Laboratory investigations

    Cannot rule in/out DCS, but may be helpful in determining the severity of DCS or finding differential diagnoses.

    • CBC.
    • CK, LDH, ALT, AST (Higher levels indicate higher severity of embolism).
    • Troponin.
    • Blood glucose.

    Imaging

    Cannot be used to rule in/out DCS.

    • Chest Xray should be obtained in patients with chest pain or dyspnea.
      • Untreated pneumothoraces are an absolute contraindication to hyperbaric oxygen therapy.
    • Head CT to rule out non-DCS causes of neurologic symptoms.
    • Limb x-rays are NOT useful in evaluating for DCS 6.

    History

    • Onset of symptoms usually occur within 1 hour, although onset past 12 hours is possible but with a low likelihood.
    • Dive profile:
      • Time.
      • Depth.
      • Number of dives done that day.
      • Type of breathing gas (e.g. Nitrox, trimix, heliox).
    • History of dive:
      • Dive computer data: Omitted/improper decompression.
      • Any difficulties encountered.
      • Rapid ascent.
      • Level of exertion.
      • Repetitive dives.

    Physical

    • Vital signs.
    • Neurological exam.
    • Features of Type 1 and 2 DCS listed above.

    Differential Diagnoses

    • Underlying cardiac or pulmonary disease.
    • Myocardial Infarction
    • Pulmonary embolism
    • Previous musculoskeletal injury.
    • Stroke.
    • Hypoglycemia.
    • Drowning/Near-drowning.

    Recommended Treatment

    100% Oxygen

    • Accelerate reabsorption of nitrogen bubbles.

    IV or oral hydration

    • Increase tissue perfusion.

    Hyperbaric oxygen therapy

    • Indicated in all symptomatic DCS.
    • Definitive treatment of DCS.
    • US Navy Treatment Table 6 is most commonly used.
    • Delay in receiving treatment of >12 hours decreases successful outcomes from 75% to 57%.
    • Patients with improved symptoms should still be evaluated for hyperbaric oxygen therapy due to a risk of relapse of symptoms.
    • View the EM Network Hyperbaric Oxygen Therapy Clinical Summary.
    • Divers Alert Network Emergency Hotline can be contacted (USA, 1-919-684-9111) 24 hours/day to assist in locating the nearest hyperbaric chamber worldwide.

    Positioning suggested for patients with arterial gas embolism

    • Supine, mild Trendelenburg, or
    • Durant’s maneuver:
    • Left lateral decubitus and Trendelenburg position.
    • However, long periods of Trendelenburg positioning or Durant’s maneuver may increase cerebral edema.

     

    Patients requiring air transport should fly in pressurized aircrafts, or in helicopters at altitudes less than 300 m.

    Aspirin, corticosteroids, and lidocaine are NOT recommended for DCS treatment due to unproven or conflicting efficacies.

    Quality Of Evidence?

    Justification

    Treatment of DCS with hyperbaric oxygen therapy is the definitive treatment and has high quality evidence.

    High

    Treatment of arterial gas embolism with Trendelenburg positioning or Durant’s maneuver has low quality evidence due to lack of studies.

    Low

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