Dizzy Spells, etc.?

[cowboyneal]

You know sometimes when you stand up fast and you get that "rush" dizzy feeling - a friend of mine (yes, really a 'friend of mine" and not me...we're not talking STDs here...lol) gets those at depth (on and off, mostly off, but every once in a while) and he has (not underwater) passed out twice in his life from standing up quickly (not recently). He is paranoid when this happens at depth (of course) because what if he passes out from it down there? Any advice on the causes of this, or its prevention or whether or not there is a serious risk? I don't want to tell him he shouldn't dive, but, well, I don't want him to go kill himself either. Tanks!

CN

 

[TSandM]

The major cause of the lightheaded feeling upon standing is a failure of the compensatory mechanisms that redistribute blood in the body with posture change to react fast enough to standing. This is termed "orthostatic hypotension". It is more common in people who have fairly low blood pressure to begin with, and is also seen in cases of dehydration or other volume loss, and in conditions that impair the sympathetic nervous system (eg. under the effects of alpha blockers). It can also be seen as a symptom of adrenal or pituitary disease.

However, the posture change explanation is unlikely to hold sway in lightheadedness underwater, unless he only experiences these symptoms when changing from a horizontal posture to a vertical one.

Other causes of lightheadedness include anything that intereferes with circulation to the brain -- heart rhythm disturbances, volume depletion -- or oxygenation to the brain. The most likely and worrisome would be an arrhythmia, particularly if your friend is older (and by this, I mean out of his thirties!) It would be worth it, in my book, for him to go get a physical which will include orthostatic blood pressure measurements and an electrocardiogram, at the very least.

 

[cowboyneal]

No, the guy is a physical specimen...and goes evey year for a physical. Has 106/64 BP and a resting heart rate of 48!!!! Not on any medications, and no history of any illness...maybe dehydration? I'll tell him to ask his doc about the other test you mentioned...orthostatic blood pressure measurements...meanwhile, is there any strategy to employ? Let's say you get a dizzy spell underwater like this - is there any way to make sure you don't black out? (Short of sticking your self with a big pin....lol). Now I'm paranoid!

Tanks!

CN

 

[TSandM]

Unfortunately, without knowing the cause of the problem, it's not possible to recommend any reasonable intervention to solve it.

Just for the sake of information, "dizziness" comes in two distinct flavors. One is lightheadedness, the feeling that one might faint. This is often accompanied by tunnel vision, sweating and nausea. It's usually a symptom of inadequate blood flow to the brain, whether that's from volume depletion of some kind (dehydration, bleeding) or from lack of pumping (arrhythmia, heart failure). This is the kiind of "dizziness" you get from standing up too quickly.

The other is vertigo, which is a sensation of spinning (or as I put it, the vertical or horizontal hold on the room has gone out). Vertigo is most commonly an inner ear problem, and is well known to occur in divers. Strategies for managing vertigo are taught a little bit in OW, and more in Rescue.

Problems with vertigo while diving may well not require any medical evaluation. Problems with true lightheadedness or near-syncope underwater would worry me a lot and make me recommend a medical evaluation quite highly.

 

[mart1]

CO2 build-up?
Happens if for instance on the descent you work hard without breathing enough. I had this happen to me a lot, until I fugured out the cause.

 

[cowboyneal]

Thats what I thought C02 buildup as a doc I know mentioned that...hyperventilation or something...who knows? As long as its not me (hahaa)...

 

[DenverDiver]

An "old divemaster" in St Croix and I talked of this same thing...short dizzy spells, 20 seconds or so. He came to the conclusion (after years) it was the rum the night before, I took it a step further and focus on staying really hydrated through the dive day. Haven't seen the problem in years...Dave