CO2 hit?

[rongoodman]

So I was doing the scenarios today for PADI Rescue Diver and came to the last one--unresponsive, non-breathing victim on the surface, at least 10 minutes from shore. Do one minute of rescue breathing and then head for the exit ASAP. I was pushing the victim, his knees against my shoulders, using a snorkel. About half way back I had to quit, out of breath, suit constricting my neck and breathing, starting to feel very unhappy, if not panicing yet. Rested for a while, same scenario again, except this time I used my regulator. No problem, other than some fatigue in my legs from finning so hard. I'm guessing the problem the first time was CO2 build up from working hard and breathing through the snorkel. Does that sound reasonable? (I hear, and contribute to, a fair amount of grumbling about PADI, but with a good instructor, Rescue Diver is a great course!)

 

[sharkattack]

Any headache? Just sounds like you were overworked. Were you holding your breath or taking half breaths?

 

[Pearldiver07]

I wouldn't call it a CO2 hit so much as CO2 build up. This will cause you to be winded much more quickly.

When you're exerting very hard (like this scenario) using a snorkel isn't the best. Your dead space is considerably larger, considering you're having to exchange air through both your breathing space AND the snorkel.

This will, in itself, contribute to a rise in CO2. I strongly suggest that if you're working that hard on the surface that you use your reg. It shortens the linear distance of the dead space, and I found actually allows me to inhale with less effort than a snorkel.

 

[scubaren]

This was happening to me with the snorkel. I cut three inches off of the top and it happens less. (I am using a Scubapro Shotgun 2 snorkel and read about cutting it down from others who have had the same problem.) It is still high enough that it is out of the water. In the event that water is extremely rough and enters my snorkel I will just switch to the reg.

 

[Ken abucs]

HMMM... this sounds like an opportunity for a new invention. How about a snorkel with a traditional purge valve in the bottom, and a one way valve in the up tube, that way when you exhale, it goes out the purge valve, and the up tube always contains fresh air. Now someone just need to figure out how you would clear such a beast.

 

[rongoodman]

I will definitely be using my regulator for such scenarios on the surface in the future, if I have one available. It was pretty sobering to think of having those symptoms 70' down, with possibly a few other issues going on.

 

[String]

Id say use the reg.

Then again, i dont carry a snorkel anyway

 

[TSandM]

I think pearldiver nailed it.

This is one of the reasons I think not liking snorkeling is not necessarily a good indicate that one won't like scuba. I don't like the obligatory higher respiratory rate you have to use through a snorkel to keep your CO2 the same. I always feel a little short of breath when snorkeling. None of that on a regulator, because there's no increased dead space.

 

[rawls]

Sounds like there could have also been a carotid-sinus reflex issue considering the constriction on the neck of your wetsuit. The receptor is telling your brain your blood pressure is too high so slow down the heart rate. The heart is therefore not pumping as much blood to your body and your respiratory rate will increase to try to find more oxygen. Just a consideration...If your wetsuit was constricting your neck it may be a good consideration to buy a better fitting wetsuit. Wearing one that constricts your neck could prove deadly.

 

[rongoodman]

The wetsuit fits OK--the constricted feeling was only there when I was working hard and using the snorkel. No problem doing the same thing on the regulator.