DCI is typically classified into two categories: Type I DCI and Type II DCI. Type I DCI is considered pain only and other mild symptoms, where Type II DCI is considered central nervous system involvement and very serious. Sometimes it’s very difficult to determine what type of DCI it is unless you’re professionally trained in diving medicine. However, it’s very important that you recognize DCI symptoms even if you’re not sure what category they fall under. Here is a breakdown of the symptoms you can expect for Type I and Type II DCI.
Decompression illness (DCI), also known as “the bends” or caisson disease, is a illness that occurs when bubbles form in your body’s tissues because of an excessive quantity of inert gas (nitrogen or helium) due to inadequate decompression following the exposure to increased pressure. During a dive, your body’s tissues absorb nitrogen or helium from your breathing gas in proportion to the surrounding pressure. As long as you remain at pressure (depth), the inert gas does not present any problems. If the pressure is reduced too quickly, from a rapid ascent for example, the inert gas can come out of solution and form bubbles in your body’s tissues and bloodstream. Once bubbles are formed they may or may not produce symptoms based on their eventual growth. When symptoms occur, they relate to the area in the body where the bubble is located.
DCI can occur as a result of violating no decompression limits and not properly decompressing during your ascent, ascending too rapidly on a no decompression dive, pushing dive tables to their limits, skipping or shortening decompression stops during a staged decompression dive, or pushing the limits on tables or dive computers when making repetitive dives. But, DCI can also occur even when you follow all of the recommended guidelines and safety factors.
Preventing DCI one hundred percent is not probable or realistic. DCI can occur even when you follow all of the guidelines and safety factors and your day to day body physiology can change, which can increase or decease your susceptibility of getting DCI.
There are a number of predisposing factors that can lead to decompression illness even when all of the appropriate guidelines and safety factors are followed. Some factors are at the mercy of the environment, such as water temperature and elevation. Other factors are physiological and pertain to each individual person, which can change from day to day and the techniques you use in the execution of your dive, ascent, and decompression.
If DCI does happen, proper treatment is very important. First aid for DCI is immediate administration of 100% oxygen either through a demand mask that cover’s the patient’s face and delivers oxygen when the patient breathes. If the patient cannot tolerate a demand mask, a nonbreatheable, free-flow mask can be used with a flow rate set to 15 liters per minute. Masks should seal to the patients face so that maximum O2 is delivered to the patient. Air leaks in the mask will dilute the O2 percentage inspired. Do not use less than 100% oxygen as a way to prolong oxygen supply. Divers Alert Network (DAN) offers a variety of oxygen kits for the diving community as well as training in their use.