Deconstructing Decompression Sickness

By Eric Douglas and Jenn Loder

One woman's firsthand account of DCS, with commentary from the DCS experts at the Divers Alert Network.

No one likes to admit they're bent. It means they've done something wrong. Errors in judgment and planning mistakes can lead to decompression sickness (DCS), but more often than not, it's a seemingly random event--the same dive profile you've done 10 times can lead to problems on the 11th, and you may never know why. What follows is the account of one woman, Jenn Loder, who suffered a DCS hit while on vacation in the Turks and Caicos. I'll pause her story periodically so my colleagues at the Divers Alert Network and I can shed some light on her experiences.

DCS briefly crossed my mind when my left shoulder started to ache at the end of my third day of diving, but I quickly dismissed it, thinking my overactive imagination was getting the better of me. After all, I was diving conservatively; I stayed well within my no-decompression limits, did my safety stops and ascended slowly. I chalked up the ache to bumping my shoulder or straining a muscle and headed for bed.

This is a classic case of denial. Divers often look for and find other reasons to explain the pain, numbness and tingling they're feeling, and though Jenn felt concerned enough to check her rescue manual, she looked for reasons why it couldn't be DCS rather than acting on the reasons that it could. In 14 percent of cases reviewed by Divers Alert Network, divers reported experiencing symptoms before their last dive, meaning they noticed something was wrong and still went back into the water, adding more nitrogen to their bodies and potentially making the situation much worse. "Divers don't call DAN because they have symptoms," says Joel Dovenbarger, vice president of DAN Medical Services. "They call us because the symptoms they have won't go away."

The next morning, thoughts of colorful reef fish, graceful rays and walls dropping off into forever filled my mind. I couldn't wait to get back on the boat and out on the reefs. But wait. That nagging ache in my shoulder was still there. Again, those pesky fears of DCS crept into my thoughts. I even went and checked my rescue diver manual to look for other likely symptoms: fatigue, chest pain, tingling. Nope, nope, nope. Again, I pushed the thoughts of DCS aside. I figured it couldn't be possible ... after all, I was a twenty-something in pretty good shape who didn't drink much or smoke at all–– what were the chances?

As the problem got significantly worse, Jenn made the right decision in recognizing the severity of the situation and informing the dive staff--before she got in the water. Dive crews are often the first responders in these cases, and though they're not medical professionals, they do have working knowledge of the symptoms. It's important to remember that there is no guaranteed diagnosis for decompression sickness--not even a doctor can give a 100- percent diagnosis--because the symptoms aren't always obvious. They can be confused with other injuries or medical conditions and easily written off as unrelated to diving.

The following are some of the most common symptoms reported to DAN, and the first three are by far the most common.

  • Numbness and tingling
  • Pain
  • Muscular weakness
  • Fatigue
  • Dizziness
  • Headache
  • Skin changes
  • Nausea
  • Vision problems
  • Mental changes
  • Unconsciousness
  • Bladder/bowel dysfunction
  • Coordination problems
  • Vertigo
  • Muscular problems
  • Hearing problems
  • Tinnitus
  • Having a combination of the above symptoms after you've recently gone diving (normally within a few hours) is about as clear-cut as it gets. If you feel unusual--divers often describe DCS symptoms as "something I've never felt before"--you're better safe than sorry. This "unusual sensation" phenomenon is most true when it comes to pain, as the pain from decompression sickness can feel different from the pain caused by exertion, bumping your arm or straining a muscle. For example, with a typical joint injury, keeping your limb still or supported will usually lessen the pain, but not with decompression sickness. Some divers describe it as a deep or boring feeling.

    One clue that your symptoms are dive-related is if you feel better while breathing pure oxygen, which helps remove nitrogen buildup from your system. These bubbles can deform body tissues and block blood flow. If you raise the oxygen content in your blood, more oxygen gets to the tissues surrounding the nitrogen bubbles and helps reduce injuries and prevent tissue damage.

    I was about 20 minutes out on the dive boat, soaking in the sunshine and speeding through the gentle waves when my left arm started tingling. Then my arm went numb from my shoulder down to my fingers. My mind was racing. At this point, I realized this was no ordinary arm injury. Even though I absolutely hated to fess up and deal with the embarrassment, I realized that getting in the water would be too risky. I described my symptoms to the dive leader and boat captain, and they immediately put me on pure oxygen and turned the boat around.

    Sitting there on the boat, my heart was pounding, my head racing, nitrogen bubbles were potentially blocking off blood flow to who-knows-what parts of my body. Despite my rescue training, it was overwhelming to realize that this was no practice run and could be a significant medical injury. As we sped toward the shore, a million things ran through my mind. Obviously, the dive operators were taking it seriously, and I couldn't decide whether to be embarrassed, terrified or relieved to be in capable hands. I did my best to avoid eye contact the entire ride back to shore. I was worried about my condition, but I was also mortified that I'd ruined the dive for everyone. It sounds like a silly concern considering the circumstances, but the social torture of being "that girl" was more awkward than a middle- school dance.

    When we reached land, the dive leader immediately took me to a local clinic (oxygen tank in tow) to speak with a doctor experienced in dive medicine. The doctor asked a series of questions about the nature of my symptoms including when they started, descriptions of the sensations I was experiencing and information about my dive profiles. He also performed some simple motor tests to determine if I still had all my movement capabilities, to find where the pain and tingling was located, and to establish if the sensation differed in my left and right arms. Ultimately, he decided that recompression in a hyperbaric chamber would be the best approach for treatment. Afterward, we'd see if the symptoms got better, which would indicate that DCS was definitely the cause.

    I then spent a very boring five-and-a-half hours in a hyperbaric chamber. During that long span in the chamber, known as a Table 6 on the U.S. Navy recompression tables, I went under pressure equal to 60 feet underwater while breathing pure oxygen, which treated damaged cells, speeding the healing process. The oxygen mask I had to wear looked like a fighter pilot hand-me-down and made me sound a lot like Darth Vader. For 25 minutes, I would breathe pure oxygen from the mask followed by a five-minute reprieve without it, so napping wasn't an option. The doctor regularly checked in over a speaker to monitor my symptoms in order to determine the length of the treatment. A tender, in my case the dive leader from my boat, stayed with me in the chamber in case of convulsions resulting from the high levels of oxygen (and as far as I can tell, to make me drink outrageous quantities of Gatorade). While we couldn't have engaging conversation, it was comforting to have someone stuck with me 60 feet under. Overall, the high pressure, small enclosure and huge oxygen mask made for a hot, sweaty and not particularly pleasant experience. Trust me, while the chamber pressure imitates being immersed in water, complete with the need to equalize your ears, there were no thrills on this very dry dive. Dr. Richard Moon, senior medical consultant to DAN, has compiled data from several years' worth of DAN statistics that shows early recognition and hyperbaric treatment could be twice as effective compared with treatment that's delayed 24 hours or more with "pain- only" or nonspecific symptoms of decompression illness. And with neurological symptoms, whether they're mild, like Jenn's, or more severe--paralysis, incontinence or mental status changes--hyperbaric treatment is at least 50 percent more effective when symptoms are recognized and treated within six hours, compared to those with a delay of 24 hours or more.

    The treatment was moderately painful, causing shooting electrical pains and tingles throughout my arm as tissue and nerve cells mended. As I lay in the chamber, thinking (since there isn't much else to do), it was hard to decide which feelings were real and which were caused by my churning imagination. When you start focusing on something hard enough and long enough knowing that your reported symptoms determine your treatment, it's hard to decipher the genuine from the imagined. It was a relief when I emerged from the chamber feeling much better. No tingling. No numbness. Not only was it comforting to discover that my symptoms had significantly improved, but it also validated that DCS was the correct diagnosis. That night and the following day I was still experiencing some periodic pains and tingles, and I wasn't allowed to fly back home until my DCS was resolved.

    I ended up taking two shorter rounds in the hyperbaric chamber, known as washout treatments, until my residual symptoms were almost completely gone. Two days after originally planned, and after a lot of hassle changing plane tickets, I was finally allowed to fly home. Luckily, I made it through relatively unscathed, not including the substantial hit to my ego.

    I left knowing that I would follow up my treatment with a dive specialist in Miami. Although I didn't have any reccurrence of major symptoms, I still had strange tingles and shooting pains every now and then, so after much discussion I decided to do another chamber treatment. After 10 cumulative hours in the chamber, I could think of about a billion things I would rather do, but one final washout treatment eliminated all of my symptoms for good. Minor symptoms, including numbness or even mild paralysis, may persist in some cases. It often takes time for divers to get complete resolution of their injuries after all hyperbaric treatments are finished. The body's natural healing process resolves many of the remaining, less-serious, symptoms. A parallel for this would be a traumatic injury where surgical repairs closed the wounds, but it takes time for the body to heal itself completely.

    The unanswered question of why this incident happened still looms in my mind. It's frustrating not to have definitive answers, and I have found that this is one of the most disconcerting aspects of dive medicine. There were other divers with profiles very similar to my own who were just fine, so what caused my DCS incident? The most likely answer is dehydration, but I'll never know for sure.

    Jenn's Advice

    Diving insurance is imperative. After much debate I, luckily, invested in dive insurance right before the trip. It saved me thousands and thousands of dollars, and ultimately provided peace of mind. Dive insurance is reasonably cheap, but if you end up using it, it's priceless.

    Dive conservatively. Following your computer or tables reduces your risk of decompression sickness but never eliminates it (after all, I was well within my computer limits).

    Stay hydrated! Dehydration is an important contributing factor to higher DCS risk. I thought that I was chugging down the fluids, but it's easy to lose track between fish sightings and sightseeing. Sun and bone-dry tank air can rapidly deplete a body's water content. Make hydration a priority in your dive plan. (Beer doesn't count!)

    Don't be too proud to listen to your body or stop a dive if you have ANY doubts. None of us wants to admit it. It's humbling, frustrating and downright embarrassing, but it's a far better choice in the long run. I hate to think what might have happened if I had ignored the signs and gotten back in the water.

    What to do if you think you have DCS Get on oxygen as soon as possible. It's your first line of defense and the only thing that'll help besides medical treatment.

    Call for help. While you're breathing in the pure stuff, call, or have someone else call, local emergency services and arrange immediate transportation to a medical facility for evaluation and treatment.

    * If you need advice, call DAN any time, 24 hours a day, 365 days a year. DAN's medical staff will help evaluate your symptoms and find you appropriate medical facilities and nearby recompression chambers. DAN Emergency Information Diving Emergencies +1-919-684-4DAN* DAN America (+1-919-684-4326) Collect EMERGENCY calls accepted

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