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==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<ref>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. </ref>
**CNS cases present more rapidly – 56% within 10 mins<ref>Francis TJ, et al. Central nervous system decompression sickness: latency of 1070 human cases. Undersea Biomed Res. 1988; 15:403–417.</ref>
**Some symptoms can be delayed for days<ref>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.</ref>

===Type I (Pain only DCS)===
*Involves the [[arthralgia|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)
***Limb weakness, paresthesias, or paralysis
***[[Urinary retention]], fecal incontinence, or [[priapism]]
*Vestibular ("staggers") involvement
**[[Vertigo]], [[hearing loss]], [[tinnitus]]
***Differentiated from inner ear barotrauma which usually occurs on descent
*Pulmonary "chokes"
**[[Cough]], [[hemoptysis]], [[dyspnea]], substernal [[chest pain]]

===Type III (Type II + [[Arterial gas embolism|gas embolism]])===
*Variety of [[stroke]] symptoms/signs
**May spontaneously resolve

==Differential Diagnosis==
{{Scuba diving DDX}}

==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<ref>Moon RE, ry sl. Guidelines for treatment of decompression illness. Aviat Space Environ Med. 1997; 68:234–243.</ref>
*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<ref>Marx et al. Rosen's Emergency Medicine - Concepts and Clinical Practice. 8th Ed. 2013. Ch 143. Pg. 1925.</ref><ref>Edmonds C et al. Diving and Subaquatic Medicine, Fifth Edition. 2015. Decompression Sickness: Treatments. Pg 173.</ref>
*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<ref>https://www.diversalertnetwork.org/medical/ Accessed 11/15/2018</ref>
**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<ref>Vann RD, et al. Decompression illness. Lancet. 2011; 377(9760):153-164.</ref>
**These include impaired urination, defication, and sexual function

==See Also==
*[[Scuba diving emergencies]]
*[[Arterial gas embolism]]

==External Links==


==References==
<references/>

[[Category:Environmental]]