| Decompression SicknessDescription - Also known as “caisson disease” or “the bends”
- Occurs most often in SCUBA diving, free diving, high altitude flying, and aerospace events
- Rapid decrease in environmental pressure causing inert gases (usually nitrogen) to form bubbles in tissues or to obstruct small blood vessels, causing symptoms
- Type I (mild):
- Musculoskeletal (70–85%): Mild joint pain that increases with time; most commonly shoulder or elbow pain
- Cutaneous (10–15%): Rash, pruritus, edema
- Type II (serious):
- Neurologic (10–15%): Headache, visual disturbance, paresthesias, paresis, paralysis, bladder or bowel incontinence, vertigo, memory loss, ataxia, seizures
- Pulmonary (2–5%): Nonproductive cough, wheezing, pharyngeal irritation, chest discomfort on inspiration, respiratory distress
- Death
ALERTPregnancy Considerations- A pregnant patient with decompression sickness is a priority, because the fetus may be affected and at greater risk for arterial gas emboli
- No contraindication to recompression therapy during pregnancy
 Epidemiology - Predominant age: 20–29 years (although there is a trend toward increased susceptibility with increase in age, especially over age 42)
- Predominant sex: Male (although no evidence suggests increased male susceptibility)
Incidence3.1/10,000 dives Prevalence< 1% even in high-density diving areas and areas of caisson work Risk Factors - Large pressure reduction (i.e. flying after diving)
- Multiple repetitive SCUBA dives or ascents to altitudes above 18,000 feet
- High rate of ascent or decompression
- Previous decompression injury
- Obesity
- Cold-water diving
- Poor physical conditioning
- Vigorous physical activity
- Dehydration
- Local injury
- Patent foramen ovale or any intracardiac right-to-left shunt (increased risk of neurologic symptoms)
GeneticsNo known genetic predisposition General Prevention - Travel by air after scuba diving should be restricted for 12 hours (after 1 dive per day) or 48 hours (after multiple dives or decompression).
- Chronic obstructive lung disease, cystic fibrosis, bronchiectasis, interstitial lung disease, or a history of thoracic surgery or prior pneumothorax should be absolute contraindications to diving.
- Intracardiac right-to-left shunts (e.g., patent foramen ovale, atrial septal defect, ventricular septal defect, patent ductus arteriosus, etc.) may be contraindications to diving.
- Follow decompression tables (Navy, National Association for Underwater Instructors [NAUI], Professional Association for Diving Instructors [PADI]) for diving to depth (>33 feet).
- Use dive computers that calculate nitrogen content of various tissues to estimate decompression limit.
- Breathing pure oxygen before exposure to a low barometric pressure environment (prebreathing) may decrease the risk of developing altitude decompression syndrome. (1)
- Pre-dive oral hydration may also reduce bubble formation. (2)
- Repeated dives and physical activity may have a protective effect. (3)
Pathophysiology - As divers descend to increased pressures, the solubility of nitrogen in tissues increases.
- As the diver ascends, this dissolved gas may come out of solution and form bubbles which can cause symptoms by blocking vessels, compressing tissue, or activating inflammatory cascades.
- Excess gas can be eliminated via respiration, so allowing for adequate breathing time is essential in disease prevention.
Etiology - Rapid ascent from diving (depth >33 feet)
- Rapid ascent/decompression in an airplane
- Tunnel work (caisson disease)
- Inadequate pressurization/denitrogenation when flying
- Flying to high altitude too soon after diving
Commonly Associated Conditions - Pulmonary barotrauma (pulmonary edema and hemorrhage; pneumomediastinum; pneumothorax; arterial gas embolism)
- Ear, sinus, or dental barotraumas
- Nitrogen narcosis
- Dysbaric osteonecrosis
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