So within 10mins of surfacing the diver is doubled over from acute pain in his abdomen. To me this reads as a typical description of a pneumothorax. The diver is exhibiting the tell-tale "guarding" while attempting to describe what he's feeling while hunched over. Is the pain truly in his abdomen or lower chest? Given the time frame <10min I'm leaning towards pneumothorax. Then the diver describes the pain spreading to other areas. Creeping "pain" is not associated with POIS or AGE. However having witnessed AGEs first hand, this may be a case where the diver attempts to explain the sensation or "ghost" feeling of an AGE as pain. The divers legs went numb a few minutes later; so now I'm really leaning towards AGE if I'm on the boat. However, AGE or DCS it doesn't really matter, he's exhibiting neurological symptoms and needs to be treated.
I can understand your thought process having come through the Navy pipeline myself. TSandM described the symptoms of pneumothorax in a previous post and I agree with her. A pneumo from pulmonary overinflation could be painless or it could present as thoracic pain, but I've seen pneumothoraces myself (though probably not as many as TSandM) and I've never seen one present as abdominal pain either. Of course if it's a tension pneumo you could also see decompensation all the way up to cardiac arrest.
When I went through dive school there was a sharp line drawn between AGE and DCS. We were still going to 165 for gas embolism and 60 for Type II, and the flow charts were completely different. There was no mention of bubble shunting, which from reading the dive profile and symptom description, is pretty high in the differential for the diver in this case. There's no way to tell for sure, of course, but the presentation of the case raises the index of suspicion.
Bubbles can be shunted through a hole or defect in the septum of the heart between the left and right atria, called an atrial septal defect. They can also be shunted through a patent foramen ovale, which is another type of defect in the atrial septum. The foramen ovale is present in utero and helps keep the fetal blood oxygenated. Typically it closes at birth but in some 30% of the population it remains open. In either case, there's basically communication between the left and right atrium. The pressure in the left atrium is only slightly higher than that in the right, and in some cases the pressure in the right atrium can actually exceed that in the left, resulting in what's known as right-to-left shunt.
Post-dive venous gas emboli, or so-called "silent bubbles", have been very well documented in divers. Most of the time these bubbles stay in the venous circulation - they come back to the right atrium, are pumped to the right ventricle and then to the lungs, where they are trapped, gradually reduced in size and eliminated. No harm no foul.
Under the right circumstances, however, bubbles in the right atrium can be shunted to the left atrium, where they're then pumped to the left ventricle, the aorta, and subsequently land in the arterial circulation. They can then theoretically go up the carotid arteries to the brain and cause AGE-like symptoms, into the spinal circulation and cause spinal symptoms, into the vestibular circulation and cause inner ear DCS, or potentially get down into the mesenteric circulation (the tissue that surrounds the intestines) and cause abdominal pain (classic "bends"). It's also been theorized that cutis marmorata (skin marbling) is a result of arterialized bubbles being trapped in the integumantary circulation.
Bubbles can also be shunted directly through the pulmonary circulation, especially during exercise. That's why they tell you not to go PT immediately after a dive or dive series with high decompression stress - you're likely to have venous gas emboli trapped in your lungs. If bubbles get through the pulmonary circulation they return to the left atrium via the pulmonary veins, then get sent to the left ventricle and can cause symptoms similar to those described above.
In either case, the symptoms present relatively rapidly, and so can be mistaken for AGE if you're going strictly by the ten minute rule. Differentiation between decompression sickness caused by shunted bubbles (sometimes called Type III DCS or simply decompression "illness") is, like you said, largely irrelevant because they're both treated the same way nowadays.
Incidentally, if a diver has an extremely high venous bubble load, say from a rapid ascent/omitted decompression, those bubbles could significantly impede the blood flow through the lungs. This results in impaired gas exchange and can lead to pulmonary edema and death. This is pulmonary DCS, or chokes.
Would you mind expanding on this? What is the textbook answer for diagnosing and treating this diver on the civilian side? The diver is exhibiting neurological symptoms of a potentially life threating diving related illness <10min after diving, why wouldn't you press him immediately?
I also dive in a civilian capacity, so I welcome any knowledge that might make me more attentive to contributing causes in others.
Usually, if it looks like a duck, etc, it's a duck. Of course the index of suspicion for DCS in this diver is high, but other medical problems also need to be ruled out. If this diver had a coagulation issue, for example, he could have thrown some microclots which would have caused similar symptoms. There are also cases in the literature of carotid artery dissection being mistaken for gas embolism. A lot depends on the diver's age and underlying medical conditions.
I was sup-ing a SCUBA dive in San Diego harbor once and one of my divers (an older guy but still a Navy diver) came up coughing up pink frothy sputum. My dive school brain was thinking, "POIS". We got him in the boat and zipped him over to the tender (forget which one) but they didn't treat him. They did an x-ray and saw pulmonary edema. Years later after working here for a while, I put two and two together and figured that this guy had likely suffered from some sort of immersion-related pulmonary edema, possibly (speculating here) complicated by age-related subclinical cardiac issues.
This my primary issue with the treatment course of this diver. For us, it is procedure that once a diver suffering a diving related illness is administered O2 they will undergo a recompression treatment. The reason being is that the application of O2 of masks and alleviates symptoms without most effectively treating the underlying issue. Further, accurate diagnosis and tracking of the symptoms can no longer be done. Case and point, the diver was administered O2 for two hours and felt better, predictably the next day the symptoms returned. The medical professionals treating him obviously suspected AGE & DCS enough to administer O2, mask symptoms, and not fully treat him?
Thanks for reading. Looking forward to your guys thoughts on this.
The fact that his symptoms were relieved by O2 definitely points toward some sort of bubble injury. I'm very reluctant to armchair judge a physician in the Bahamas while sitting at my desk in North Carolina because I didn't see the diver myself and there's often more to the story than meets the eye here on Scubaboard. Still, I agree with this statement and I'd be interested to hear the physician's rationale for not treating this diver in a chamber.
