Atrial fibrillation

1) Disease Description (Causes and Symptoms)

• Definition and pathophysiology: Decompression sickness (the bends, decompression illness) occurs when inert gas (primarily nitrogen) dissolved in tissues and blood separates into bubbles during rapid ascent from deep water or a sudden decrease in pressure, physically injuring blood vessels and tissues or obstructing blood flow. The bubbles cause microvascular obstruction, mechanical compression, inflammatory responses, and endothelial damage.
• Major causes and risk factors: Rapid ascent (insufficient decompression), deep and prolonged diving, repetitive diving, dehydration, excessive physical activity, air travel (taking off after diving), and increased risk in people with underlying cardiopulmonary disease or a cardiac interatrial shunt (e.g., a patent foramen ovale).
• Major symptoms: Joint pain (especially in the shoulders, knees, etc.), skin symptoms (itching, decreased skin turgor, rash, redness), numbness and tingling, dizziness and vertigo, chest pain and shortness of breath (pulmonary involvement), and neurological symptoms (motor paralysis, speech impairment, decreased consciousness), among others. Symptoms usually occur from immediately after diving to within 24 hours, but they may develop later.

2) Treatment Methods and Precautions

• First aid (at the scene/during transport)
  • Immediately administer 100% oxygen (maintain the highest possible concentration, whether via mask or nasal cannula).
  • Keep the person at rest and prohibit excessive movement or exertion (to prevent bubbles from moving or increasing).
  • The left lateral decubitus position (the Durant position: left lateral decubitus with the head slightly lowered) may help reduce the risk of venous bubbles moving into the systemic circulation.
  • Transport the person as quickly as possible to a facility capable of providing hyperbaric oxygen (recompression) therapy. Continue 100% oxygen during transport.
  • Fluid replacement (IV) is often recommended (to maintain circulation and improve blood flow).
• Standard treatment
  • Recompression therapy (hyperbaric oxygen therapy) is the primary and definitive treatment (using standard protocols such as US Navy Table 6). Early recompression is associated with a good prognosis.
  • Repeated treatments may be necessary, and multiple treatments, such as 20 sessions, may be required for severe neurological symptoms.
• Adjunctive therapy (in specific situations)
  • Adequate fluid administration and continued oxygen therapy.
  • Anticoagulants (e.g., heparin), blood-volume expanders (e.g., dextran), and steroids may be considered in some cases, but they are not standard treatments and require specialist judgment.
• Precautions for pain management
  • Nonspecific or indiscriminate administration of analgesics may interfere with symptom assessment and treatment decisions, so follow the clinician’s instructions. (Self-administering analgesics at the scene is not recommended—use only under specialist judgment.)
• Contraindications and precautions
  • Pulmonary function must be evaluated before recompression therapy (e.g., hyperbaric treatment may be contraindicated if pneumothorax is present).
  • If symptoms occur after diving, do not dive again for self-treatment.
  • Avoid air travel and exposure to high altitudes until recovery.
• Complications and prognosis
  • Most people respond well to early hyperbaric oxygen therapy, but some may have residual effects such as permanent neurological deficits, chronic fatigue, sensory disturbances, or osteonecrosis (diving-related bone necrosis).

3) Checklist Before an Outpatient Visit (Including Sample Questions)

• Items/information to prepare
  • Diving records (date/time of diving, maximum depth, dive duration, whether repetitive diving occurred, ascent rate, and whether safety stops were performed)
  • Time of symptom onset (how many minutes/hours after diving), symptom progression (patterns of worsening/improvement), and a current list of symptoms
  • List of medications being taken (prescription drugs, OTC medications, and supplements)
  • Medical history (cardiopulmonary disease, smoking, whether PFO has been diagnosed, and any previous history of decompression sickness)
  • Details of treatment provided at the scene or during transport (whether oxygen was administered, body position, etc.)
• Things to show the medical staff during the visit
  • Dive computer, if available, or a snapshot of the records
  • Notes documenting the symptoms (when they occurred and what you were doing)
• Preparation for testing and evaluation
  • Measurement of basic vital signs (respiration and oxygen saturation) and a physical neurological examination are necessary.
  • Blood tests and imaging studies are adjunctive (specific findings may be lacking).

4) Examples of General Questions to Ask the Doctor

• "Do my symptoms appear to be decompression sickness? Do I need immediate recompression therapy?"
• "What are the expected benefits and side effects of recompression therapy (hyperbaric oxygen therapy)?"
• "After this incident, when can I safely go diving again?"
• "If I am currently taking any medications, will they affect the treatment?"
• "How great is the risk that I will have residual effects (neurological damage)?"

5) Examples of Disease-Specific Questions

• "Given my diving profile (depth/duration/repetitive diving), what decompression procedures should I change to reduce the risk of recurrence?"
• "Could a right-to-left intracardiac shunt (e.g., a patent foramen ovale) affect the severity of decompression sickness, and if necessary, should I undergo PFO testing (such as echocardiography)?"

(Note: Diagnosis is primarily based on the clinical history and physical examination, and the treatment and plans for additional testing and management should be determined in consultation with the treating specialist.)