Does diving influence blood pressure?

[ScottB]

Just something I've been wondering..

While actively diving, (or just being in a hyperbaric environment?), in general does blood pressure increase, decrease or remain the same? Both systolic and diastolic?

Only asking out of curiosity, does not effect my diving plans, I *have* been cleared by my doc to dive...

Well.. I'll stop over using smilies for this message

Thanks, take care,

 

[mislav]

I'm also interested to know the answer to this question.

I have a friend with a high blood pressure who might become a diver. I've never thought that there may be some health risks involved. Thanks for posting this and opening my eyes.

 

[ScottB]

Mislav,

There is a very good chance that your friend will be able to dive safely even with hypertension (high blood pressure).

http://www.scuba-doc.com/hyptdiv.htm discusses some of the issues of hypertension and diving..

I am not a doctor and recommend your friend seek assitance from a qualified doctor who dives or has experience with divers..

In light of this based on the information I have gained from scuba-doc, it appears that diving with controlled hypertension without major complications is within reasonable safety limits.

HOWEVER, concern *must* be taken regarding different medications used to treat hyptertension and diving.

I hope that helps you,
Take care,

 

[knotical]

Interesting question.

I’m neither a physician, nor physiologist, so take the following speculation with an extreme grain of salt:

Since we survive dives to significant increased pressures, obviously our hearts keep comfortably pushing blood around our bodies. And since liquids are essentially incompressible, the absolute pressure throughout our bodies must follow approximately the same as our surrounding pressure. It then follows that the differences in pressures (systolic, diastolic) would retain their relative differences at depth. Therefore if we measured 120/80 at the surface, then used a depth/pressure-compensated sphygmomanometer at depth, we’d still see 120/80. But if we measured absolute pressures, we’d see absolute numbers very close to the ambient for any particular depth.

I look forward to someone more knowledgeable correcting me.

 

[Gene_Hobbs]

While actively diving, (or just being in a hyperbaric environment?), in general does blood pressure increase, decrease or remain the same? Both systolic and diastolic?

Just a thought, but there can be a lot to your question... To quote Drs. Mebane and McIver, "Hypertension and diving present a problem without a simple answer" (Chapter 4, Fitness to Dive, Bennett and Elliott, 4th Edition). For example, a quick search in our repository for "immersion blood pressure" will give you 1524 results. And we are not even half way through entry of all the work that needs to be added. Take a look around and you might narrow your question some. <http://archive.rubicon-foundation.org/>

One of my favorites is work we are currently doing "123456789/3664". I will try to add an image of the table later today. PA Pressures have been fun to watch. We are still in need of volunteers if anyone wants to participate. <http://www.dukehealth.org/clinicaltrials/20050411132656655?subject=>

Take care,
G

 

[Gene_Hobbs]

Interesting question.

I’m neither a physician, nor physiologist, so take the following speculation with an extreme grain of salt:

Since we survive dives to significant increased pressures, obviously our hearts keep comfortably pushing blood around our bodies. And since liquids are essentially incompressible, the absolute pressure throughout our bodies must follow approximately the same as our surrounding pressure. It then follows that the differences in pressures (systolic, diastolic) would retain their relative differences at depth. Therefore if we measured 120/80 at the surface, then used a depth/pressure- compensated sphygmomanometer at depth, we’d still see 120/80. But if we measured absolute pressures, we’d see absolute numbers very close to the ambient for any particular depth.

Not a bad way to look at it... duration of exposure, temperature of water, work, etc. aside.

 

[ScottB]

Thank you knotical and Mr. Hobbs,

Mr Hobbs, I am looking through the archives now, however, I have attempted to simplify my question:

A person at the surface at restis under 1 atmosphere of pressure and their blood pressure is 120/70 mmHg (absolute) (roughly 2.32/1.35 psig, 17.02/16.05 psia)

Given the same person is 10 meters/33 feet underwater, *OR* in a hyperbaric chamber simulating a dive to 10m/33ft, at rest, therefore under 2 atmospheres of pressure, what would their theoretical blood pressure (absolute)..

Considering only the change in the ambient pressure.. I am *guessing* that effective blood pressure increase by 1 atmosphere, 14.7 pounds, 760mmHg for roughly each 10m/33ft of depth? A resulting resting bloodpressure of 880/830mmHg at 33 ft.. I bet my doctor would love to see that <grins>

So, am I a crackpot? =)

Takecare and thanks again,

 

[Gene_Hobbs]

So, am I a crackpot? =)

not at all, fun question really... It will be roughly the same for either case. Effects of immersion will lower blood volume over time (diuresis, respiratory loss, hypothermia, etc.) and you will see a HR and eventually BP response to those over time but for the most part, there should not be any noticeable change.

Changes to the body with immersion are pretty interesting... Especially when you think about changing pathology like say someone with congestive heart failure or some type of shunt.

Take care,
G