Aspirin and diving

[Dr Deco]

Hello WaterDawg:

As you have read, the blood is not really “thinned,” that is, made less viscous. As for the change in surface tension, I doubt much of a change with aspirin. There is not really any evidence that surface tension changes among divers nor that it has any relationship to susceptibility to DCS. That is more a pet theory of mine (and a few others), but there is not any proof other than the Walder study of 1948 which people do not seem to be able to replicate. :06:

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology :1book:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[pescador775]

HOWEVER...in actual and experimental DCS, where bubbles form directly within the spinal cord, these areas have been noted to become hemorrhagic (i.e., bleed), which would make DCS worse, and moreso if the blood doesn't clot normally. This was seen quite clearly on slides of post-mortem specimens

"would" and not "could"? So, is this an assumption or a fact? Are you suggesting a buildup of pressure in the cord? Just how typical would you say that the particular exposure models were? Moderate or severe? Did the discussion move to post bends effects such as immune reactions which could lead to inflammation, long term damage and how that might be modified by steroids or non steroidal meds like aspirin? To your knowledge has fish oil concentrate (EPA, DHA) ever been investigated in regard to suppression of long term effects? (Fish oil is a known anti- inflammatory).
TIA
Pesky

 

[ScubaDadMiami]

As was pointed out, aspirin and other NSAID's decrease/prevent platelets from clumping together, starting clot formation. Aspirin's effects are permanent (platelets live ~10 days in the blood, meaning about 10% turnover/d) which is why aspirin can be given every other day to prevent clots; diclofenac, and the many other non aspirin NSAIDs affect the platelets only as long as the drug is in the system--8 or so hours for ibuprofen, greater than 24 hrs for piroxicam, most others in between.
That said, Aspirin doesn't "thin" the blood per se, it only prevents the "thickness" that occurs with clotting. (And the pressure on bubbles is hydrostatic related to depth, not because blood is "thick" or "thin"). As the inflammatory effects of bubbles in vessels may lead to platelet aggregation, aspirin may help prevent some of the effects of DCS.
HOWEVER...in actual and experimental DCS, where bubbles form directly within the spinal cord, these areas have been noted to become hemorrhagic (i.e., bleed), which would make DCS worse, and moreso if the blood doesn't clot normally. This was seen quite clearly on slides of post-mortem specimens I just saw at a DAN conference. Thus there wasn't a lot of enthusiasm for recommending Aspirin as a DCS preventive. Yes it might help prevent some manifestations of DCS, but it might make some (especially serious CNS DCS) worse.
After diving, especially if several hours have passed without obvious DCS, aspirin and NSAIDs would seem generally safe.

As usual, this is meant as a general discussion, not specific medical advice, nor is a doctor-patient relationship implied.

I wonder if this would change if the diver were on a daily regimen of 81 milligram aspirin (and had been for some time prior) as opposed to taking it only before diving. Was there any mention of this?

 

[pescador775]

In lieu of further info I need to do some follow up elsewhere. In the meantime my spidey sense says this: They gave the animals a severe to fatal case of bends complicated with bleeding at certain nodes. The non control animals were given aspirin which increased the bleeding. Test results presented with the following comment, "see, the aspirin killed them".

If DAN is interested in the other 95% of bends susceptibilities then they are on the right track. I say 'susceptibility' because if ASA (aspirin) actually does prevent some cases it cannot be called a 'case' at all if it doesn't happen.

Recently, it has been reported that some individuals are 'aspirin resistant'. This is FYI and pertains to those who take ASA for heart issues.

I wonder if this would change if the diver were on a daily regimen of 81 milligram aspirin (and had been for some time prior) as opposed to taking it only before diving. Was there any mention of this?

 

[kelpdiver]

Wow, 10 months after posting, it's a hot topic, but my recall of the details of the talks are fuzzy. And I apologize if I've missed comments in other related threads; I haven't been on this board very often.
Pescador, whoa! These weren't studies testing aspirin and no one was blaming aspirin for DCS. I'll retract my "would" and say "could," but if my spinal cord was looking like those I saw, I would prefer not to have aspirin on board because it COULD make the bleeding worse. (On the other hand, if I'd had a stroke or MI, I'd be taking aspirin, and diving conservatively, as I think the risks of having another vascular event would outweigh the risks of making spinal cord DCS worse than it already was.)
The animals presumably weren't on aspirin. I don't know how much anyone has studied the issue of use of ASA/NSAIDs/fish oil pre or post dive on development or outcome of CNS DCS. Perhaps Dr. Deco knows. Hard to do controlled studies like this on people. I know of one study treating dogs with mega-dose steroids after they developed spinal cord DCS, by the same Navy researcher (Francis) who (I think) helped formulate the notion of autochthonous CNS bubbles. They did worse than controls.
ScubaDad, I don't think it would matter if the ASA were taken daily or just once before diving--the anticoagulant effects would be similar.

 

[iainwilliams]

Hi Wendryn,

Just to add my 10 cents worth here.

When I am diving for several days in a row I always take 1 asprin tablet per day with food.

As stated, the asprin removes platlets which in turn will not accumulate around small nitrogen bubbles that form after several days of diving (asymtomatic bubbles). Asprin also has a anti inflammatory effect on the body, therefore, advantages could be found around joints and the like in inhibiting asymtomatic nitrogen bubbles from accumulating & growing in this area.

The downside is that should you have an accident, you will have dimminished platlets to assist with blood clotting of the wound. Furthermore, the asprin will mask mild symptoms of DCS, and can produce stomach lining upsets.

I always use anvil (trademark name) which is less harsh to the stomach lining.

Whether the use of asprin actually minimises DCS I do not know - all I know is what I have gleaned from others and have read. I have used anvil for years now with no side effects and I have not been bent, but I always err on the side of caution with my diving profiles and never lug heavy tanks after a dive or pull up anchors post dive - that is what the boat boy is for! Of interest is the placebo effect of a drug - I've been told it is as high as 30%!!

Hope this may help...............Iain