Decompression sickness

Background
  • Also known as "the bends"
  • Dissolved nitrogen (and occasionally helium) comes out of solution and forms bubbles in blood and tissue
  • Occurs in rapid ascent in diving, and more rarely in military operations rapid ascent in high altitude aviation or hypobarics training

Clinical Features
  • Symptom typically start soon after surfacing
    • 42% in 1 hr, 60% in 3 hr, and 98% in 24 hr[1]
    • CNS cases present more rapidly – 56% within 10 mins[2]
    • Some symptoms can be delayed for days[3]

Type I (Pain only DCS)
  • Involves the joints and extremities, with constitutional symptoms
  • Usually only single joint is involved, most commonly:
    • Shoulder
    • Elbow
    • Knee
  • Skin and lymphatics
    • Pruritus, stinging, paresthesias, hot/cold sensations
    • Fine scarletiniform rash from nitrogen movement through sweat glands
    • Cutis marmorata - marbling rash, purplish-bluish discoloration, otherwise common and normal in infants
    • Pitting edema, peripheral swelling from lymphatic blockage

Type II (Serious DCS)
  • Some consider multiple joint involvement qualifies as Type II
  • Spinal cord involvement
    • Ascending paralysis
    • Signs often cannot be traced to single location in the cord (may have skip lesions)
  • Vestibular ("staggers") involvement
  • Pulmonary "chokes"

Type III (Type II + gas embolism)
  • Variety of stroke symptoms/signs
    • May spontaneously resolve

Differential Diagnosis

Scuba Diving Emergencies

Workup

Decompression sickness is a clinical diagnosis

  • Pain may be reduced by BP cuff inflation over the joint to 150-200 mmHg
  • In patients that are ambiguous or decompensated, consider additional workup without delaying definitive treatment
  • Other considerations
    • Fingerstick
    • CBC
    • Chem10
    • Lactate
    • PT/PTT
    • VBG (or ABG)
    • Ethanol level
    • Consider UDT

Management

Treatment based almost solely on case reports and series

  • ABCs/BLS/ACLS
  • Denitrogenation with 100% NRB regardless of SpO2, and continue 2 hours after symptom resolution
  • Keep supine, Trendelenburg not recommended[4]
  • Initiate IV crystalloid fluids, rate of 250 cc/hr for first few hours
  • Hyperbaric oxygen
    • Effective even in delayed cases
    • Immediate recompression for suspicion of Type 2 DCS, in consultation with hyperbarics specialist
    • Do not wait for recompression, but if delayed presentation, may recompress up to 14 days after symptom onset[5][6]
  • If due to high altitude aviation or hypobarics
    • Descend to ground level ASAP
  • Contact Divers Alert Network (DAN) Emergency Hotline at 1-919-684-2948[7]
    • Similar function as to poison control
  • If patient requires transport to another facility, consider ground transport, air transport at max of 1000 ft, or air transport with pressurization capability
    • O2 with tight fitting mask during flight
  • Consider adjuncts such as Lidocaine, Perfluorocarbon emulsions

Disposition
  • Hyperbaric chamber and admission

Prognosis
  • One study showed at an average of 6.1 yrs, almost 50% of patients had impairments[8]
    • These include impaired urination, defication, and sexual function

See Also


References
  1. Navy Department. US Navy Diving Manual. Revision 6. Vol 5: Diving Medicine and Recompression Chamber Operations. NAVSEA 0910-LP-106-0957. Washington, DC: Naval Sea Systems Command, 2008.
  2. Francis TJ, et al. Central nervous system decompression sickness: latency of 1070 human cases. Undersea Biomed Res. 1988; 15:403–417.
  3. Freiberger JJ, et al. The relative risk of decompression sickness during and after air travel following diving. Aviat Space Environ Med. 2002; 73:980–984.
  4. Moon RE, ry sl. Guidelines for treatment of decompression illness. Aviat Space Environ Med. 1997; 68:234–243.
  5. Marx et al. Rosen's Emergency Medicine - Concepts and Clinical Practice. 8th Ed. 2013. Ch 143. Pg. 1925.
  6. Edmonds C et al. Diving and Subaquatic Medicine, Fifth Edition. 2015. Decompression Sickness: Treatments. Pg 173.
  7. https://www.diversalertnetwork.org/medical/ Accessed 11/15/2018
  8. Vann RD, et al. Decompression illness. Lancet. 2011; 377(9760):153-164.
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