Decompression sickness

Disease Description (Causes and Symptoms)

• Definition and causes: Diver’s disease (decompression sickness) is a condition in which inert gas dissolved in the body (mainly nitrogen), after exposure to a high-pressure underwater environment, separates into bubbles as pressure decreases during ascent, causing mechanical and chemical damage to blood vessels or tissues. Rapid ascent (rapid decompression), deep and prolonged dives, and repetitive dives are risk factors.
• Pathophysiology: When dissolved nitrogen forms bubbles, it causes microvascular obstruction, impaired blood flow, inflammatory responses, tissue ischemia, and neurological damage.
• Main symptoms: Skin symptoms (itching, rash, skin swelling/changes in skin tension), joint pain (especially in the shoulders and knees), tingling and numbness, dizziness, chest pain, shortness of breath, changes in consciousness, and paralysis (serious when the central nervous system is involved). Symptoms generally develop within minutes to 24 hours after diving.

Treatment Methods

• Initial emergency treatment (at the scene/during transport)
  • Immediately inhale 100% oxygen (maximize inspired oxygen).
  • Keep the patient stable and prevent excessive movement and physical exertion.
  • If possible, establish intravenous access and provide sufficient fluids (to maintain circulation).
  • Position: According to the provided reference materials, the left lateral decubitus position is recommended; however, actual treatment should follow the instructions of an emergency physician (some guidelines recommend a flat position, lying supine).
  • Transport the patient as quickly as possible to a facility capable of providing hyperbaric oxygen therapy (recompression therapy; hyperbaric oxygen therapy; HBOT).
• Definitive treatment
  • Recompression therapy (hyperbaric oxygen therapy): This is the standard treatment. The patient inhales 100% oxygen in a high-pressure environment to reduce bubble size and promote the redissolution of nitrogen into tissues. Repeated sessions may be necessary depending on the symptoms and severity (multiple treatments may be possible for neurological symptoms).
• Supportive treatment
  • Consider pain control, anti-inflammatory drugs, fluid therapy, anticoagulation if necessary (at the physician’s discretion), or supportive treatments such as steroids and dextran (depending on the treatment protocol and the patient’s condition).
  • Early rehabilitation in cases of neurological damage (physical therapy and occupational therapy).
• Precautions (during treatment and self-care)
  • If symptoms are suspected, visit a medical facility immediately, even if the symptoms are minor.
  • Do not attempt to dive again on your own as a treatment.
  • Medication for pain relief should be administered under a clinician’s judgment. Unwarranted use of painkillers may affect symptom assessment and the treatment plan, so caution is needed (the provided reference materials recommend treating this carefully).
  • Avoid flying (air travel) until symptoms have completely resolved and a physician has given permission (the recommended waiting period after severe/complex dives should be followed).

Checklist Before an Outpatient Visit (Including Example Questions)

• Items/materials to prepare
  • Record your recent diving history (when, depth, dive duration, ascent rate, whether a safety stop was performed, and whether there were repetitive dives).
  • Note the time symptoms began and how they have progressed (changes since onset).
  • List all medications currently being taken (including prescription drugs, over-the-counter drugs, and supplements).
  • Medical history (cardiopulmonary disease, cerebrovascular disease, diabetes, coagulation disorders, etc.) and any previous diving-related accidents.
  • If shortness of breath, chest pain, or neurological deficits (paralysis, sensory abnormalities, speech impairment) occur, visit an emergency room immediately.
• Things to tell the medical staff in advance when visiting an outpatient clinic (examples)
  • “When was your most recent dive, and how deep did you go?”
  • “When did the symptoms first appear, and how have they progressed?”
  • “Are you taking any medications regularly?”

Examples of General Questions to Ask the Doctor

• “Do I need hyperbaric oxygen therapy (HBOT) for my symptoms? How many treatment sessions are expected?”
• “What are the possible side effects and risks of the treatment?”
• “How long should I avoid diving or air travel?”
• “What lifestyle changes should I make to reduce the risk of recurrence?”

Examples of Disease-Specific Questions

• “Which factors in this dive (depth, time spent underwater, or repetitive diving) may have been particularly risky?”
• “If neurological symptoms (such as tingling or paralysis) remain, what is the likelihood of future recovery, and what will the rehabilitation plan be?”

Additional Information

• Most cases of diver’s disease respond well to early treatment (especially HBOT), and some symptoms, such as joint pain, may persist for several days to several weeks. Severe neurological damage may leave long-term sequelae, so early evaluation and treatment are important.
• Prevention: Follow decompression procedures as taught in diving training (ascend slowly and perform safety stops), allow sufficient intervals between repetitive dives, avoid diving when excessively overweight, dehydrated, or fatigued, and allow sufficient time before air travel (the recommended time varies depending on the type of dive).