Blacking out while diving

[TMHeimer]

I've got a bungee cord attached to my reg mouthpiece that goes around my head. Should I ever black out, there is a good chance I will still be breathing. I solo dive most of the time and at times use nitrox, so this is a lot cheaper than a full face mask. I figure it's a good idea even when with a buddy in case he doesn't see I'm unconcious--even if he does notice right away, I'm still not going to inhale any water. I never use it when DMing classes for obvious reasons. I didn't think 3 feet of bungee would cost $13.

Other posts have mentioned that there is no reason for a normal healthy person to blackout while on scuba. Years ago I read of a 38 year old former olympian female runner who was still in tip top shape suddenly die of a heart attack while jogging. I know the risk of that is very miniscual, but thus the bungee cord. Of course, I hope I never see a shark as well. There may be other rare reasons for passing out. When I was a kid I fainted twice. For some unknown reason you could have a gas imbalance while diving--like way too much CO2. Or something could scare the S*^t out of you.

 

[Nemrod]

What can cause a diver to blackout? I have been reading somewhere that it can happen in shallow water and deep water, and it's one of the the major reasons why you should never dive alone. Is blacking out a major concern for a diver?


thanks in advance

If you have occasional black outs aside from seeing a doctor right away that is reason enough alone to never scuba dive. There is nothing in normal scuba diving that would cause a healthy person to blackout.

I do not get stomach cramps when swimming after eating and I do not black out so I guess it is okay for me to solo dive since I have been doing so since I was 14 years old. I fly aircraft solo as well even on instruments.

N

 

[Sam Miller III]

no applicability to the modern diver

 

[GrumpyOldGuy]

Oxygen toxicity or CO poisoning are dive related risk that could cause a blackout. A buddy is probably not the best solution to prevent either, very likely it means 2 victims instead of 1 as buddies will tend to have tanks filled from the same source. There are good reasons to buddy up, this is not one of them. Oxygen levels and CO can be detected with the proper equipment before you dive if your fill station is questionable.

For some perverse reason, "experts" sometimes like to scare new divers with old yarns in order to get them to dive like they do.

 

[DaleC]

I'd be more concerned about blacking out while driving.

 

[R-balljunkie]

Oxygen toxicity or CO poisoning are dive related risk that could cause a blackout. they do.

Both of these are from pushing the limits. blend or exceeding NDL depths. gonzo stuff.
second is bad health. stroke. heart attack. other medical issues.....aside from this, you should be more than fine.

 

[kensuf]

Without knowing more specifics on any particular accident...

Usually when referring to "shallow water blackout" the victim is engaged in apnea (free diving). Basically the free diver did something (frequently hyperventilating) to reduce their CO2 levels enough that they can stay submerged at depth for an extended period of time, metabolizing O2 as they stay. While they are at depth, due to the hydrostatic pressure they are under, the PO2 is enough to keep them awake. As the free diver ascends the PO2 in their blood drops, and if it goes below ~0.16, they're probably going to take a nap.

For someone on scuba that blacked out while in shallow water on scuba, and with everything else being OK (good air, gear in working order, etc), I'd say look at other underlying physiological issues that may have been exacerbated by the mammalian diving reflex. Hypertension/diabetes/hypoglycemia/heart conditions come immediately to mind.

In deep water on scuba, CO2 buildup, overexertion, and narcosis come immediately to mind.

 

[FinnMom]

CO poisoning is not always from gonzo stuff, sometimes it from bad air, caused for example by a compressor whose intake was able to suck in exhaust gases. Testing tanks for CO seems to be something we're beginning to accept as a real & reasonable need.

__________________________


Another very uncommon reason for blackout on scuba gear could be from a drysuit neck seal that is too tight. Seriously, it can happen. From what i have read it can depress carotid artery supplying blood to the brain and decreasing blood supply (arterial blood carries i.e. supplies oxygen) and thereby causing blackout.

If you wonder why a diver might not notice a deteriating state of conciousness, it's a little easier to understand if you realize that diving frequently engages your attention very well, so minor symtoms /changes can go unnoticed. It's like having a headache/toothache that doesn't bother you until you go to bed and have nothing better to think about.

 

[GrumpyOldGuy]

Both of these are from pushing the limits. blend or exceeding NDL depths. gonzo stuff.
second is bad health. stroke. heart attack. other medical issues.....aside from this, you should be more than fine.

No, CO is beyond the control of a normal diver and undetectable unless you have specialized equipment. It is introduced though the compressor systems used to fill the tanks. You either trust the people maintaining the system or buy a CO detector.

I agree though, health issues are much more likely cause of blackouts, diving or topside.

Oops - Finn Mom beat me to the punch...

 

[Nemrod]

I'd be more concerned about blacking out while driving.

Yeah, me too. I do not get this fabrication, and that is what it is, a premise that people just black out. If you have epilepsy or some other condition that is a contradiction to diving and certainly true that a few people could have such a contradiction and not know it but, that said, healthy people do not just black out randomly.

You can worry about a meteor hitting you too. Let's see, I think I have blacked out maybe three times in my life, all were the result of a high speed impact with something more solid than me, most recently, four years ago when I smacked the ground at 30 MPH as a result of being attacked by friendly pit bulls while riding my bicycle fast in an effort to get to the first episode of Shark Week.

Yeah, uh, I do not just go around blacking out so y'all can leave me out of your black out fantasy. And if this is some sort of back door swipe at solo SCUBA, try harder, this one will not work as a reason not to solo dive.

N