Hypercapnia - Are You Diving High ?

Hypercapnia .... that sounds pretty serious. Yes it can be. Let's first define what this is and I will try to explain it. Definition: (also called hypercarbia) or excess carbon dioxide, can result from many causes. I will explain each to these.

1. BREATHING RATE, IMPROPER BREATHING

Most common cause when a diver fails to breath slow and deep. If he does then you have small tidal volume (amount of air inhaled and exhaled during normal breathing), and high proportion of dead air to fresh air in the alveoli. Carbon dioxide levels in the alveoli and bloodstream increase, causing headaches, confusion, and a further accelerated breathing until the divers slows down and resumes deep, slow breathes. If unchecked, this elevated increase in carbon dioxide can lead to loss of consciousness.

In closed and semi-closed scuba gear, ( rebreaters ) and full face mask, have been associated with hypercapnia due to large dead air space (portion of divers tidal volume that plays no direct part in air / gas exchange.) However, in open circuit scuba used in recreational diving, hypercapnia due to dead air space is rare, but can happen.

2. HEAVY WORK UNDERWATER

If diver attempts heavy work underwater, muscle tissues can produce carbon dioxide faster than the respiratory system can eliminate it. This increase in carbon dioxide causes the respiratory center to stimulate a higher breathing rate to get rid of this increase. Because of the denser air breathed at depth, this requires more effort by the diaphragm and other muscles to overcome resistance from turbulence. This additional effort furture increases carbon dioxide production, resulting in yet a higher demand for increased breathing. This cycle continues until the diver slows down or stops activity, after which, the respiratory system catches up with the body gas-exchange needs.

3. SKIP BREATHING

This is holding your breath while scuba diving in order to extend your air supply. In reality, this techniques leads to an increase in carbon dioxide in their circulatory system, until it actually stimulates faster breathing and therefore helps to deplete air supply faster.

4. AIR SUPPLY CONTAMINATION

Contaminated air is rare in recreational diving. But it is always a good idea to breathe from your regulator prior to the dive to ensure the air taste "fresh". Part of the BWRAF procedure. The symptoms are the same as for improper breathing.

Bottom line: Breathe at a slow, deep, and unlabored rate. This will keep you safe, and allow you more "air" time underwater.