What is Hyperventilation

Hyperventilation is the breathing response kicked off by chemical changes in the blood such as high CO2 or low oxygen level. It can also be set off by an acute panic attack or anxiety attack. It occurs mainly in out of shape, inexperienced divers or in divers with malfunctioning regulators. It can be managed simply by assisting the diver to the surface in a controlled fashion from behind, holding the regulator in the divers mouth. Since the diver is breathing, there’s little need to worry about pulmonary over pressure accidents from breath-holding. The diver blows off excessive quantities of CO2 thus lowering the serum calcium level, which can result in ‘tetany’ – a condition in which the muscles go into involuntary spasm. On the surface, the condition is managed quite well by rebreathing into a paper bag – thus elevating the CO2 level, the calcium level with a resultant return to normal of the neuromuscular activity.

What Causes Hyperventilation?

Hyperventilation is an unreasoning rapid breathing associated with psychological shortness of breath or feeling of smothering and is one of the symptom complex of a panic attack. It feeds on itself by producing a marked lowering of the pCO2 (carbon dioxide levels) with an associated drop of blood calcium levels resulting in tetany (spastic loss of muscle function). This results in a vicious cycle — pushing the diver into a peripheral narrowing and locked into panic driven behavior. Rapid breathing can also be caused by faulty equipment, causing a retention of CO2.

Peripheral Narrowing

Dr. Glen Egstrom, in “Stress and Scuba Diving”, states that peripheral narrowing causes such panic driven behavior by the diver with ineffective problem- solving, even in the highly trained individual.

What to Do?

The physical effects of hyperventilation can be solved nicely on the surface by rebreathing CO2 in a paper bag or other distensible sack. This is impossible at depth and hyperventilation becomes an emergency requiring a controlled assisted ascent, with the strong possibility that rescue will be needed on the surface, due to the ineffectual, inappropriate behavior caused by the focused peripheral narrowing of the panic attack.

Should the Diver Continue to Dive?

The diver should have an independent skilled technician check out his scuba gear, paying close attention to his regulator. If this is not a problem, the diver should ask himself:

  • Am I prepared to dive anymore? Scuba is fun, not a contest.
  • Are there any physical reasons which might have caused my over breathing? Did I have a cold, gastroenteritis, fatigue, hangover or was I terribly out of shape for the type of diving that I was doing?
  • Am I a “Dragooned” diver as Dr. Jeff Davis called the diver that was diving to please a friend or spouse? Is my training adequate for this type of diving or has it been a long time between diving trips?
  • Is the environment difficult, with high current, rough seas, cold water or bad weather?

All of these things can cause anxiety to start and, as has been noted, it can feed on itself and rapidly grow unmanageable. One should freely admit to pre-dive insecurity and get the dive guides to stay near you in order to assist if needed.


Ernest S. Campbell, M.D., FACS

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