Blood pressure when diving

[boulderjohn]

Perhaps this could explain higher rates of heart attacks in scuba than in other sports? But only if you are cold. I am more interested in the effect of the higher pressures on the body at depth which is not much in the above test in a swimming pool at shallow depths.

Are there higher rates of heart attacks in scuba than in other sports? I have not seen those statistics.

If there is a higher rate (and there could be), another reason could be that scuba tends to attract an older population for several reasons. In my younger days, I was a basketball coach and player, a volleyball coach and player, a soccer coach and player, and a citizen ski racer. I don't do any of those activities any more, in large part because of the toll those activities took on my body. When I was planning for one of my knee surgeries, I asked the orthopedist when I could get back to full activity, and when she gave me a date in the fall, I said, "Great, because I have to register for the ski racing season by next week, and I wanted to be sure I would be ready." She asked, "You race on those knees?" I said, "Yes, I do." She said, "No, you don't."

My son was an avid soccer player playing in a number of adult leagues, but he has given it up for the same reason and is looking for a less punishing activity to replace it. For me, the less punishing activity I sought out as I aged was scuba. My aching knees loved the effortlessness of diving.

It is very possible that I may some day have a heart attack while diving. I did not have a heart attack while playing those other sports, but the reason would not have anything to do with those sports being less demanding of my heart functions.

 

[TSandM]

Bazzer, I seriously doubt that there is any difference with depth of immersion. Remember that the body is almost all water, and pressure equalizes across liquid essentially instantly. Blood pressure is the pressure added to the blood by cardiac contraction; it's the transmural pressure experienced by the blood vessels. There are changes in this from immersion, which is clear, but whether you are at 6 feet or 60, the transMURAL pressure will be the same unless something else (workload, temperature, or even anxiety) changes.

There are other studies on the Rubicon site which address hemodynamics in saturation divers, but I didn't think that was what you were interested in. You might spend some time searching there, if you want published studies. The site is linked in my sig line.

 

[Bazzer69]

Boulderjohn, I do not know the stats for heart attacks whilst diving, or for any other sport, but I recently completed my PADI OW and several times our instructor mentioned heart attacks as the leading cause for death whilst diving. I ask about BP not only about heart attacks but stroke as well. You can of course have either without high BP but you have a elevated risk of either if you do.
I guess no real studies have been done.


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---------- Post added July 10th, 2014 at 08:10 AM ----------

Ah ha, should have use the search function in the first place! http://www.scubaboard.com/forums/ba...44-how-does-diving-affect-blood-pressure.html


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[boulderjohn]

Boulderjohn, I do not know the stats for heart attacks whilst diving, or for any other sport, but I recently completed my PADI OW and several times our instructor mentioned heart attacks as the leading cause for death whilst diving. I ask about BP not only about heart attacks but stroke as well. You can of course have either without high BP but you have a elevated risk of either if you do.
I guess no real studies have been done.

Your instructor was correct in saying that heart attacks are the leading cause of death while scuba diving. That is true by far. I am also sure that heart attacks are the most common cause of death in golf, also by far.

That does not mean that there are a lot of heart attacks in either sport. It means there aren't many other things causing fatalities. The lesson is not that scuba is especially liable to create heart attacks; the lesson is that if you follow your training properly, scuba is pretty safe. The next leading cause of death in scuba, the one you need to be aware of while diving, is a sequence of events starting with running out of air without a buddy nearby. That's a situation you should look to avoid.

 

[TSandM]

That thread on blood pressure has almost no useful information. Even the study on hyperbaric chamber blood pressures is not relevant to diving, because the subjects were not immersed. The study I cited at least had the subjects compared between being underwater and being dry.

Elevated BP increases cardiac workload, to be sure -- if you have a critical lesion in one of your coronary arteries, a sudden, marked increase in workload may be enough to cause an arrhythmia or a plaque to rupture. (We do know that some MIs occur during sex, for example, when adrenaline is high, or when shoveling snow.). One hopes that people with critical stenoses like that have been diagnosed and warned to avoid exertion until the problem is addressed, but there are people out there with unrecognized coronary disease. However, they are risk from ANYTHING that raises blood pressure, including having an argument with their spouse

The increased risk of MI and stroke with elevated blood pressure, however, is a matter of CHRONIC elevation. When we talk about blood pressure as a risk factor, we are talking about the chronic disease of hypertension. If brief periods of elevated blood pressure were a risk factor for vascular disease, we'd see all our top athletes with high rates of MI and stroke, which is precisely the opposite of what happens.

So, if you have multiple risk factors for cardiac disease -- if you're a heavy smoker, diabetic, have chronic hypertension, sky-high cholesterol, are obese and unfit, or have a big family history for heart disease -- it's a good idea to get some kind of medical evaluation for your fitness to participate in ANY sport or physical activity. If you're a young, healthy individual with no known heart disease, I do not think you need to worry about elevating your lifetime risk for cardiac disease by undergoing transient elevations in blood pressure, such as appear to occur with diving.

 

[Bazzer69]

We'll, I'm going to avoid my spouse in the future. Diving and fly fishing are in my future! Oh, my doc says I'm fine to dive. And I don't shovel much snow down here in San Diego


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[Pao]

A little bit OT but the pathophysiology of heart attacks and most strokes is ischemia or lack of O2 in the tissues. Will the increased PO2 at depth have a protective effect? Although it is not acknowledged that nitrox increases exercise capacity there is a lot of anecdotal evidence that it does. Theoretically it is like exercising on supplemental O2 which can increase your exercise capacity.

 

[TSandM]

The pathophysiology of both MI and stroke is blockage of the blood vessels, so no, the increased ppO2 won't help. You would think it might buy time, since there's more dissolved oxygen in the blood on the downstream side of the obstruction, but in point of fact, virtually all the oxygen in the blood is carried by hemoglobin, which is 99% saturated at a ppO2 of .21 (in someone with normal lungs). Oxygen is very poorly soluble in plasma, and increasing the ppO2 doesn't increase the total oxygen in the blood by much at all.