1.4 Decompression Sickness

• What is another name for decompression sickness?

  Bends
• What causes decompression sickness in divers?

  Nitrogen bubbles forming in body fluids
• How does the pressure change when a diver ascends to the surface?

  Pressure decreases from 5000 mm Hg to 760 mm Hg
• What happens to nitrogen gas when a diver ascends rapidly?

  Nitrogen escapes and forms bubbles
• What percentage of people with decompression sickness experience joint pain?

  85 to 90 percent
• What are the symptoms of decompression sickness?

  Joint pain, dizziness, paralysis, shortness of breath
• What is the term used for the nervous system symptoms in decompression sickness?

  Nervous system symptoms
• What is "the chokes" in decompression sickness?

  Shortness of breath due to lung capillary blockage
• How much nitrogen is eliminated in 1 hour if a diver ascends slowly?

  About two thirds
• What do decompression tables provide for divers?

  Procedures for safe decompression
• What is the decompression schedule for a diver at 190 feet for 60 minutes?

  10 min at 50 ft, 17 min at 40 ft
• Why is tank decompression important for treating decompression sickness?

  It allows gradual pressure reduction to prevent bubbles
• What is saturation diving?

  Divers live in a compression tank for extended periods
• Why is helium used in deep dives instead of nitrogen?

  It has lower narcotic effects than nitrogen
• What is the effect of helium on decompression sickness?

  It reduces the volume that dissolves in tissues
• What happens to airway resistance when using helium in deep dives?

  Airway resistance decreases due to low density
• What is the risk of high oxygen concentration at great depths?

  Oxygen toxicity can cause seizures
• At what depth does a 1 percent O2 mixture suffice for divers?

  700 feet
• What is the PO2 at 700 feet with a 21 percent O2 mixture?

  More than 4 atmospheres
• How does the pressure at 700 feet affect oxygen delivery?

  It increases the risk of oxygen toxicity