The risk of hyperventilation in people in general is very common. Men, women, and children have all hyperventilated and it is a condition that is easily dealt with for those who are on dry land. Hyperventilating while diving is fairly common as well, particularly in divers who are inexperienced, those who are out of shape, and in divers whose regulator is malfunctioning. What is hyperventilation? It is simply a breathing response that is brought about by chemical changes in the blood. These chemical changes can be things such as low carbon dioxide levels and blood calcium levels can also drop. As the hyperventilation continues there is a progression of symptoms that occurs, including tingling in the fingers and around the mouth followed by headache and dizziness and, ultimately, hyperventilation can cause tetany, which is a condition in which the muscles will begin to spasm involuntarily.
So how does a diver begin to hyperventilate? This condition is generally brought on by a rapid breathing that is itself brought on by a panic in the diver. Maybe the diver psychologically feels short of breath or feels like they are smothering. Maybe the diver is in a situation in which they have become tangled or entrapped in something or they have lost their buddy and feel unsafe. A faulty regulator can also cause a diver to hyperventilate. Hyperventilation in and of itself is generally easy enough to treat when on dry land. Simply have the person who is hyperventilating breathe into a paper bag or other type of distensible bag will alleviate the condition quickly. The problem is when a diver begins to hyperventilate while underwater.
The diver who hyperventilates underwater is in an emergency situation and requires an assisted ascent. This is because unlike on land, where the hyperventilating person has an unlimited air supply, the diver has a limited air supply and can go through their cylinder of air very quickly, so quickly that they can turn 30 minutes of bottom time on a 19 m (60 foot) dive into five minutes of bottom time. Once the diver becomes low on air, which is due to hyperventilating, the diver becomes more stress and hyperventilates even more.
The early symptoms of hyperventilation, the tingling of the fingers and mouth, can easily be mistaken for symptoms of the bends, otherwise known as decompression sickness. If a diver is already hyperventilating and becomes stressed by this, it can make the situation far worse. If the diver has hyperventilated enough for tetany to set in, the diver often gets locked into a panicky cycle of hyperventilation and tetany. This cycle has been termed peripheral narrowing and can lead to the regulator falling out of the diver's mouth and to drowning. Tetany can come on for even the most experienced of divers and when a diver is assisted to the surface emergency medical help may be required.
A diver who has hyperventilated while diving might wonder if they can go back to diving once hyperventilation has stopped. The first thing that should happen is that a dive technician should check over all of the diver's equipment, especially the regulator. If this is all working fine, then the hyperventilation was not brought on by faulty equipment and this means that the diver must consider other possible causes. Maybe the diver is inexperienced and was just diving with friends or family as a tag along. Maybe the diver was diving in conditions for which they did not have adequate training. Maybe the diver was diving with a cold or other health condition, such as gastroenteritis, extreme fatigue, or even a hangover. Maybe the diver was just too out of shape, without the proper level of fitness for the dive conditions or maybe the diver simply hadn't been diving in a long time and was out of practice.
The diver has to consider all of these possibilities and has to also consider the diving conditions in terms of depth, strength of current, weather and water temperature, and rough water conditions in general. The diver also must consider whether or not they are prepared to dive anymore that day. After what happened, is the diver truly in any shape to get back in the water or would the diver just be risking another hyperventilation attack?
Divers can prevent hyperventilation by being fully prepared to dive in the conditions that are present at the time of the dive and at the skill level that the dive demands from the diver. Divers can also prevent hyperventilation by being fit enough to dive and by ensuring that they are in good health. Ultimately, the diver must be aware of their breathing. Avoid deep sighing breaths and short shallow breaths. Moderate-sized breaths are ideal. If a situation happens that may be an emergency, a diver must Stop-Breathe-Think-Act. In other words, stay calm and remember to breathe while you determine what to do about the situation. This will help you and other divers remain safe while under the water.