Dizziness is a common occurrence. Most people have an episode of dizziness at least once in their lives, even if it is just a head rush that comes on from getting up too fast. Dizziness is a feeling of lightheadedness that is generally caused by low blood pressure which is often low enough to cause reduced blood flow to the brain. Vertigo occurs when there is an abnormal stimulation of the balance mechanism that resides in the middle ear which often results in dizziness. While dizziness may not present much of a problem on dry land, a diver who experiences any form of dizziness while underwater may end up in serious trouble if the situation is not handled properly.
While there are many causes of dizziness, there are a few that are of particular concern when it comes to scuba diving. One such concern is hyperventilation which is a condition that is brought on by rapid breathing. It is not uncommon for a diver to hyperventilate and many divers are often unaware that they are doing so. When this happens there can result a low level of carbon dioxide in the blood and this can result in problems. The decreased levels of carbon dioxide cause the pH of the blood to rise, which in turn causes the restriction of the blood vessels that supply the brain with blood, leaving the brain short of oxygen and other important molecules. As the hyperventilation episode 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. In the worst case, a diver may experience a blackout. In order to stop hyperventilating or reduce the risk of hyperventilation, it is important for a diver to breathe slowly and deeply, even if he or she feels short of breath.
Vertigo can be brought on by a variety of situations. On descent, a diver can experience vertigo if they suffer a barotrauma to the inner ear. When a diver is ascending, the pressure changes in the two middle ears can be different, leaving the diver with dizziness and vertigo. This condition is called alternobaric vertigo and can be halted if a diver slows down the rate of the ascent allowing the two middle ears to reach a common pressure. Another situation in which vertigo can result is when the ears are exposed to different levels of cold temperatures. If one middle ear experiences a colder temperature than the other, say by lifting the dive suit hood on one side and exposing the ear to cold water, this difference in temperature between the two middle ears can result in the uneven stimulation of the balance mechanism, causing vertigo. If you are diving in cold water in a wetsuit, you may very well experience vertigo if proper measures are not taken to avoid it, but should not experience a problem diving in a dry suit because there is less of a chance of cold water getting into the ear. Finally, a viral infection can cause vertigo if it affects the balance mechanism of the middle ear. Labrynthitis is one such virus.
If the dizziness is not caused by hyperventilation or a middle ear imbalance, then it is possible that there is an abnormal heartbeat that is causing it. A rapid heartbeat or a heartbeat that is too slow can cause dizziness to occur. High blood pressure and low blood pressure are also known to cause dizziness and people who are on medication to lower the blood pressure may experience dizziness if the blood pressure drops too low.
In the end, if there is no obvious cause of low blood pressure, then an evaluation must be done to determine the cause of it. If the diver is otherwise healthy, then there is generally no problem with pressure on the ascent or descent or an issue with temperature. However, if there is an underlying cardiovascular problem it must be diagnosed and treated before the person can resume diving. If the inexperienced diver has frequent issues with hyperventilation, then diving with an experienced diver for a number of dives may help to relax them in the water.
No one wants to have their dive interrupted by a sense of dizziness or vertigo. If this does happen, then it is important to stay calm, breathe, and think about what might be causing it. If you are ascending or descending, then stop and let your ears pressurize properly. Pay attention to your breathing rate. Most cases of dizziness and vertigo can be easily taken care of by following these simple guidelines allowing you to dive safely and enjoy the very activity you love most – diving.