Incident Insight reprinted from Alert Diver magazine
By Marty McCafferty EMT-P DMT
>The diver was a 19-year-old woman in good physical condition. She denied any history of medical problems and did not take any medications regularly. She completed her confined-water training several weeks before with no problems and was now doing her open-water training dives.
>The dives took place in South Florida. The diver was accompanied by her father, a certified diver with fewer than 100 lifetime dives. On the first day the dives were uneventful, though the diver admitted to some anxiety related to being in open water and diving from a boat. None of the dives were deeper than 30 feet or longer than 40 minutes. She successfully performed all required skills and reported looking forward to completing her certification.
>On the second day the dives were at a different location. The boat was anchored over a 13-foot-deep sand bottom. The bottom sloped downward to the reef, which was at a maximum depth of 35 feet. After they entered the water and began heading toward the reef, the diver's father and other witnesses reported that the diver appeared to be having difficulty with her equipment. Exactly what was wrong was never clearly established. Her movements appeared erratic, and she seemed unaware of her buddy or other divers. Within moments she ascended quickly in an uncontrolled manner from 13 feet to the surface. Upon reaching the surface she appeared to struggle and did not establish positive buoyancy. Her father made a controlled ascent to the surface and was able to establish positive buoyancy for both of them. The diver had already abandoned her mask and regulator and was breathing rapidly. With aid from one of the dive guides, the pair returned to the boat.
>Aboard the boat the diver was shaking and continued breathing rapidly. The crew examined her, and she reported tingling in her hands, dizziness, and aches in both arms from the shoulders to the elbows. The crew placed her on oxygen via a demand valve. Since they were only 20 minutes from shore, the dive operator sent a small boat to take her and her father back to the dock. They were met by emergency medical technicians (EMTs), who continued oxygen administration at 12 liters per minute using a nonrebreather mask. The diver's symptoms did not change during the five-minute ride to the hospital.
>The attending physician performed a thorough neurological evaluation and did not note any deficits. The diver reported that the tingling in her hands was still present and also complained of a tingling sensation in her face. The aching in her arms had not improved, nor had the dizziness. Normal blood test results ruled out other potential causes for her symptoms, and a chest X-ray did not reveal any lung injuries or other abnormalities. Her breathing rate remained elevated, and she appeared quite distressed.
>The dive had been very shallow, and the risk of decompression sickness (DCS) was virtually nonexistent — even considering the rapid ascent. There were, however, few other good explanations for her symptoms. The doctor contacted the local hyperbaric physician for consultation. Although neither doctor believed her symptoms represented DCS, in the absence of another clear diagnosis they believed treating her in the chamber was the safest option. She was transported by ambulance to the hyperbaric facility, which was approximately 30 minutes away. The hyperbaric physician treated her with a U.S. Navy Treatment Table 6. The muscle aches resolved within the first 20 minutes at 60 feet. As she became less stressed and her breathing rate slowed to normal, all the tingling resolved as well. She was discharged approximately six hours later with no residual symptoms. In a phone call the next day she denied any return of symptoms, and no further treatment was deemed necessary.
>The dive profile as reported does not represent a risk of DCS. The dive was shallow, and witnesses stated that it did not last more than 10 minutes. It is highly unlikely that there was sufficient decompression stress to have precipitated DCS at the time of the rapid ascent. Furthermore, there would have been little to no residual nitrogen left from the previous day's dives. Whether the previous day's dives were contributory or not, however, will never be definitively established.
>The major concerns with a rapid ascent are a breath-hold leading to a lung-overexpansion injury and, potentially, an arterial gas embolism (AGE). Based on the diver's presentation and subsequent evaluation, her symptoms did not suggest an AGE. (AGE typically presents similar to a stroke.) Tingling sensations and muscle aches are among the many signs and symptoms of DCS, but it is unusual for tingling to be present in both hands with DCS. Aches and pain are also potential symptoms of DCS, but again these are more commonly seen in one arm and occur in major joints more often than in muscles. Although DCS was extremely unlikely, based on these symptoms it could not be completely ruled out.
>There is no medical imaging or lab test that can verify DCS. Tests and imaging are still useful, however, because DCS is most often diagnosed by ruling out other possibilities. In this woman's situation there was no clear explanation for her symptoms. Hyperventilation can produce tingling in the hands and face, and the doctor suspected that her struggling, especially at the surface, probably caused muscle fatigue that could explain the aches in her arms. Retrospectively, insufficient exposure, atypical symptoms and no objective findings exclude DCS as diagnosis. Some physicians, however, would rather err on the side of caution, and this doctor consulted with another physician trained in dive medicine. Probably the most compelling factor for considering chamber treatment in this situation was the fact that treatment constitutes a very low risk to the patient. Both physicians expressed the opinion that this was probably not DCS, but they wanted to act in the diver's best interest.
>The fact that the muscle aches improved with treatment seems to support the DCS diagnosis, but it does not necessarily do so. Breathing 100 percent oxygen at increased atmospheric pressure produces an anti-inflammatory effect — even aching or pain due to muscle fatigue would improve in the chamber. In this case, time or the placebo effect may have been the factors that most facilitated symptom resolution.
>Other physicians or facilities may have opted not to treat this diver in the chamber, which also would have been reasonable. Most physicians try to make decisions that are in the best interest of the patient. As always, DAN® is available to divers and health-care professionals to assist in the decision-making process.
>© Alert Diver — Q3 Summer 2016