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Status of Research in Underwater Physiology, Prepared for the Office of Naval Research, Washington, D. C. by the Physiology Group, Panel on Underwater Swimmers, Committee on Undersea Warfare (1956) / Chapter Skim
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RESPIRATION
Pages 20-22

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From page 20...
... While tolerable limits for added dead space has been defined for resting conditions such as air or oxygen breathing at sea-level pressure and at altitude, these limits are not necessarily acceptable in underwater breathing apparatus either at rest or at work. Both added external dead space and an increase in the physiological dead space tend to decrease the effective pulmonary ventilation and may readily result in values which are prohibitively low.
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From page 21...
... If these changes in depth are extremely rapid and the respiratory movements normal, the net result in descent may approach that accomplished in breathholding; in ascent may resemble hyperventilation. If true breathholding is practiced, as in skin diving, the mass of air in the lungs remains constant, except for pulmonary exchange, and the lung volume varies inversely with depth; in this situation, effective pulmonary ventilation is essentially absent and man's performance is limited by individual tolerance to changes in lung volume and to partial pressures of oxygen and carbon dioxide in the lungs.
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From page 22...
... to increased ambient pressure. Therefore, a sound approach to the development of such equipment cannot be made until the physical and physiological aspects of diving are more firmly established.
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Key Terms

  • breathing resistance
  • pulmonary ventilation
  • underwater breathing
  • negative breathing
  • breathing equipment

  • resting conditions
  • breathing device
  • tidal volume
  • breathing apparatus
  • lung volume

  • tolerable limits
  • adequate pulmonary
  • appreciably increased
  • various gas
  • added external

  • respiratory spaces
  • ambient pressure
  • skin diving
  • external dead
  • thereby reduced

  • specific underwater
  • body temperature
  • compensatory response
  • prohibitively low
  • considerable amount

  • physiological dead
  • increased pressure
  • response impractical
  • displacing water
  • dioxide removal


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