Beta Blockers

[InTheDrink]

I use beta blockers. I have typically avoided using these when diving as they lower blood pressure and I don't have any idea what effect that could have when diving. Any thoughts? What does low or lower blood pressure have when diving? On the surface it makes one's muscle's more tired doing things that would normally. And I am not looking for a psychological evalutation thx a mill. J

 

[Charlie99]

See Divers Alert Network article. DAN Divers Alert Network : Cardiovascular Medications and Diving

Beta blockers are not a good choice for a diver. Perhaps you can get your doctor to work with you on trying other types of medicines such as ACE inhibitors and/or calcium blockers and diuretics.

Commonly used to treat hypertension, beta blockers have a big drawback: they can reduce the heart’s capacity for exercise and therefore affect your exercise tolerance.

This could potentially cause problems if you needed to exert yourself, such as in assisting another diver with problems, or if you need to swim against a strong current.

Charlie Allen

 

[adurso]

What does low or lower blood pressure have when diving?

syncope: loss of consciousness

 

[TSandM]

It's not clear what you are using beta blockers for, that you can stop them when you are diving. Abrupt withdrawal of beta blockers, when you are using them regularly, can result in some nasty side effects, including very high blood pressure and very rapid heart rates.

Beta blockers are also used to control abnormal heart rhythms, in which case abrupt withdrawal is probably even more hazardous.

If you are maintained on beta blockers to control high blood pressure or for some other routine indication, and you do not experience excessively low heart rate or blood pressure while using them, it's unlikely you will experience those things underwater. Beta blockade can limit exercise tolerance, however, and as Charlie pointed out, that might put you at a disadvantage in certain stressful situations. Some people with healthy hearts can exercise heavily on beta blockers, though, so it's something that's worth experimenting with on land, to know what's likely to occur underwater.

For most indications, there are other medications which can be used, whose side effects are not as significant.

 

[InTheDrink]

MY heart is fine, I use them periodically for anxiety, or high stress situations like large presentations (which I find very stressful!). Normally I use them prior to an event, such as a presentation, but at the moment I take one daily for ongoing anxiety. I exercise when using them - I notice it's a lot more tiring.

Thanks for the feed back - I'll keep it simple and just avoid using them when diving.

John

 

[DocVikingo]

Hi JClynes,

Here's an edited piece on beta blockers and diving I wrote last year:


"Beta Blockers & Diving:

Interactions between beta-adrenergic antagonists and SCUBA reside both in the drug's intended and unintended effects.

As regards intended effects, beta-blockers interfere with the actions of adrenaline on beta receptors. Among other things, they slow nerve impulses traveling through the heart. As a result, the heart does not work as hard and arterial BP is decreased.

Now, this desired limitation in cardiac output may undesirably reduce exercise tolerance such that possible unexpected rigors of diving (e.g., very intense currents, a buddy rescue, a long surface swim in rough conditions) cannot be negotiated. It is for this reason diving medicine recommends that those taking beta-blockers be able to attain, or closely reach, 13 mets upon exercise stress testing without angina, shortness of breath, EKG abnormality or other worrisome event.

As regards unintended effects, otherwise termed adverse reactions or side effects, of concern to the diver is that this class of drug can cause cold hands and feet, vomiting, tiredness, dizziness/lightheadedness and anxiety. It obviously would not be good if sedative effects interacted with increased partial pressures of nitrogen to exaggerate narcosis, or if anxiety predisposed to diver panic. It is for this reason that, as with all drugs, a beta-blocker should be given an adequate topside trial to assess for problematic side effects before attempting SCUBA.

Finally, as regards the effects of the increased ambient pressures inherent in SCUBA on blood pressure, there seem to be none of significant concern. While some cardiac changes do occur with SCUBA, such as increased heart rate and decreased stroke volume, neither systolic nor diastolic BP appear to be meaningfully affected over the long run.

In conclusion, otherwise healthy and fit divers taking only a modest dose of a beta-blocker seem at very little additional risk due to the medication. Should there be issues, there is a wide variety of alternative classes of drugs to manage HBP."


Since you are "not looking for a psychological evaluation," no more will be said on the topic beyond that the diver with trait or state anxiety should be aware that these may predispose to diver panic and potentiate nitrogen narcosis.

Helpful?

DocVikingo

This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual and should not be construed as such.

 

[InTheDrink]

Hi DocVikingo,

Thanks for the very informative post. Didn't understand all of the terms but certainly got the gist. In any event, I don't see any reason to take them while diving if there can be any unwanted effects.

And as far as the psychological evaluation that we're not doing : as long as I'm not giving a presentation to a large audience underwater, I don't see myself as pre-disposed to panic and I've had opportunities to find out. On the contrary, under water is probably the one place my anxiety - or at least the kind of anxieties that require beta blockers - fully disappears. Out of curiousity - what is trait and state anxiety?

 

[Jay_SMART_Diver]

Beta Blockers lower blood pressure by decreasing the "squeeze" or force of the heart's contraction.

 

[DocVikingo]

My pleasure.

State anxiety is a transient response to more or less specific situations that are perceived as threatening, such a public speaking.

Trait anxiety is a generalized and enduring predisposition to respond with anxiety to a range of situations perceived as threatening. Those in this group tend be anxious more of the time.

Clearer?

Regards,

DocVikingo

 

[DocVikingo]

Beta Blockers lower blood pressure by decreasing the "squeeze" or force of the heart's contraction.

Hi Jay,

That description may be viewed as a bit simplistic.

This type of medication reduces the force of the heart's contraction, the amount of blood the heart pumps out with each contraction and lowers heart rate.

Regards,

DocVikingo