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  1. Duke Dive Medicine

    Vertigo And Tinnitus

    Hi @Eastwest , is there a question here? Best regards, DDM
  2. Duke Dive Medicine

    Question Isolated subcutaneous emphysema?

    Re the pressure of diving and its influence on subcutaneous emphysema, good question. The difference between the subq emphysema that you've seen in the ED and an event that occurs while diving is the reduction in ambient pressure on ascent, which will cause any pockets of subcutaneous air to...
  3. Duke Dive Medicine

    Question Isolated subcutaneous emphysema?

    Hi @SeaMarie , Subcutaneous emphysema from diving would have most likely arisen from some kind of pulmonary barotrauma. How experienced a diver are you? What were the diving conditions like? Depth? Sea conditions/waves? Do you recall holding your breath at any point in the dive? Small...
  4. Duke Dive Medicine

    Question Deserved DCS hit even with deco cleared due to high exertion during the dive?

    PFO is associated with sudden-onset severe neurological DCS, inner ear DCS and cutis marmorata (skin marbling). Given the OP's description of symptoms and onset time, a PFO test would not be indicated. Best regards, DDM
  5. Duke Dive Medicine

    Empty Tanks???

    Hi David, High-pressure cylinders can be extremely dangerous and are not something to experiment with if you don't know exactly what you're doing. There are a lot of great scuba shops in San Diego that I'm sure would be happy to help you verify that they're empty. Best regards, DDM
  6. Duke Dive Medicine

    Why doesn't oxygen cause decompression sickness?

    Some fine detail points to add to this. First, this is a strictly theoretical discussion. For all practical purposes, divers will not have O2 bubbles in their blood. However, should a diver manage to survive breathing O2 at a high enough partial pressure to potentially produce bubbles on...
  7. Duke Dive Medicine

    Diving after pneumothorax

    Hi @stevel97 , What was the illness, and what does your pulmonologist think caused the pneumothorax? Best regards, DDM
  8. Duke Dive Medicine

    Why doesn't oxygen cause decompression sickness?

    Thanks @rjack321 for the photo. This is similar to the hoods we use. We also have Scott aviator double-hose O2 masks for the rare claustrophobic patient who doesn't tolerate the hood. Best regards, DDM
  9. Duke Dive Medicine

    Why doesn't oxygen cause decompression sickness?

    Thanks for that callout. Mechanical damage is probably a bit of an oversimplification. The damage is subtle - the lining of the blood vessels is disturbed by the bubble to the point that the inflammatory cascade mentioned by @Dr Simon Mitchell is activated. This can lead to capillary leakage...
  10. Duke Dive Medicine

    Why doesn't oxygen cause decompression sickness?

    I think you're getting at arterial oxygen content, which is a function of hemoglobin level, O2 saturation (percentage of hemoglobin taken up by O2, normally 95-100%), and arterial partial pressure of O2. The answer to the question I think you're asking is, in a healthy individual, arterial...
  11. Duke Dive Medicine

    Why doesn't oxygen cause decompression sickness?

    That's a big if as noted above. A more likely scenario might be a combat diver on a 100% O2 CCR who experiences a gas embolism. An oxygen bubble would resolve much faster, but depending on size and duration, could also cause an inflammatory reaction that could in turn lead to neurological...
  12. Duke Dive Medicine

    Why doesn't oxygen cause decompression sickness?

    As noted above, most oxygen is carried by hemoglobin in red blood cells at sea level, where the inspired partial pressure of oxygen is .21 ATA. Still, there is a small amount of oxygen dissolved in the plasma at this pressure; a normal arterial pO2 value is 85-100 mmHg. Divers breathe O2 at...
  13. Duke Dive Medicine

    Calcium Score and Fitness to Dive

    Weird. Sorry about the technical glitch, glad you got an appointment! Best regards, DDM
  14. Duke Dive Medicine

    Calcium Score and Fitness to Dive

    Hi @ljwillia , What was the indication for the coronary calcium score test? Given the information you've provided, it looks like your husband has multiple risk factors for a cardiac event and I'd strongly recommend he be evaluated by a diving physician. Richmond isn't far from Durham, we're...
  15. Duke Dive Medicine

    Studies on outcomes of omitted decompression - how badly do you get bent for x minutes of skipped deco, aka how risky is a dive?

    That's a really interesting insight. It seems like you're recognizing the possibility of becoming complacent, which could lead to drift from a good safety mindset and safe diving procedures. And, I basically just said the same thing that @crofrog wrote while I was typing this :wink:
  16. Duke Dive Medicine

    Studies on outcomes of omitted decompression - how badly do you get bent for x minutes of skipped deco, aka how risky is a dive?

    Any empiric study of significant omitted decompression on humans would be unethical. There are animal models that purposely omit large amounts of decompression, but those studies are mostly to examine the pathophysiology of DCS. And, some of those animals don't get bent despite the...
  17. Duke Dive Medicine

    Question Deserved DCS hit even with deco cleared due to high exertion during the dive?

    Lymphatic DCS causes generalized swelling in the area drained by the affected lymph vessels. Swelling can be a symptom of extreme dehydration, but in a young, otherwise healthy person that seems unlikely. As noted by @arkstorm above, dehydration is not the lurking villain that some people make...
  18. Duke Dive Medicine

    Question Deserved DCS hit even with deco cleared due to high exertion during the dive?

    You may never be able to pin down an exact cause of this DCS event, assuming it's DCS. Decompression algorithms are not iso-risk, that is, the probability of DCS for any given decompression algorithm increases with increasing depth and bottom time. Specific to this dive, heavy work and cold on...
  19. Duke Dive Medicine

    DCS recovery and next steps advice

    Great question. Frank ischemia with a very large bubble load, possibly. The more common mechanism of injury of DCS is a relatively short period of reduced blood flow followed by an inflammatory reaction at the capillary level. This is harder to detect on MRI. Best regards, DDM
  20. Duke Dive Medicine

    Dive medical post Pulmonary Embolism

    Just a point of clarification on this. The mechanism of injury in pulmonary embolism is that the clot breaks loose, usually from an extremity, travels through the venous circulation and the right side of the heart, then to the pulmonary arteries. The clot then may obstruct blood flow through...
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