how to "pad" my stops

[Hellvet]

I am looking to "pad" my stops as i have just been diagnosed with a PFO. I have been allowed back in the water with limits(20m max, 1 dive/day, richest nitrox mix on air tables, slow ascents).
I am not sure whether to just spend slightly longer at each depth - i.e. if i am supposed to do 1min at 9m and 3 min at 6m according to tables then do 3@9m, and 5@6m, or whether to add stops in in addition to those asked for by tables or computer at different depths e.g at say 12m, etc etc.
I generally add a 3min safety stop at 6m, and plan to continue to do this, but am unsure whether i would benefit more from adding in deeper stops, or by extending the stops i would already been doing.
I am not planning on doing a lot of deco diving, but will probably add deco to my non-deco dives, to add a safety margin, so would appreciate any advice. I will probably not be doing any diving until i have seen Dr Wilmshurst anyway, but am interested in the principle...

Helen

[Mark Chase]

Surely medical advice needed here, as doesn’t a PFO shunt gas across to the wrong side of the hart causing unavoidable bends. I thought this was caused but sudden strain or coughing or something as benign as that?

Ignoring the PFO as I don’t know much about it.....


What sort of diving are we talking about?

The most important thing in say 35m max Nitrox deco is to do the ascent from 10m to 6m very slowly as between 10m and the surface is the area for massive bubble growth. From 6m to the surface normally takes me 4 -5 min's. On a 30m dive I start thinking about pausing / stopping on a no deco dive around 15m. I would say of equal importance is to get off nitrogen and think about 100% 02 as the gas of choice from 6m up. Stay on the surface on 02 and breath 02 climbing the ladder then sit and chill out on the boat breathing 02 until your breathing rate is normal and take your main kit off breathing 02 then come off the gas.

If your feeling tired after so called normal diving with normal deco than this should help. Even if no deco diving a 3ltr of 02 is worth having if your pushing anywhere near NDL's and just run your back gas tables and let the 100% pad it for you.


ATB

Mark Chase

[Gavin Smith]

Given the thhat you are going to be diving as rich Nitrox as possible on air tables at less than 20m I think you are going to have plenty of safety factors built in.

If you include a longer safety stop (how long can you bear to hand around the 3-6m mark) then there is little else you can do in reality except switching to something really rich I would have thought.

Good luck!

Gavin

[MATTBIN]

I'm guessing as I'm no doc, but 20m max on Nitrox isnt going to get you into deco unless you either breath very light or take masses of gas and that's why they suggested these limits, they dont want you going into deco territory.

[Edit] Just realised as a ldy diver you probably do breath very light (damn blast) so you might well get into deco even on a 12L cylinder.
[Edit]

Ean 40 (from my Suunto) gives about 80 mins at 21mtrs NDL.
Air tables give about 40mins NDL, I'd stick with that air limit and avoid deco completely.

I would pad the 3min stop at 5/6 mtrs to 5mins and ascend very slowly.

Matt

[chrisch]

One thing to consider is the valsalva manouvre - try to avoid this and equalise by swallowing with the tongue at the top of the mouth. Valsalva causes shunts!!

PS swallowing too much air is bad as well BTW....

Hope you get it all sorted soon.

Chris

[NotDeadYet]

It's called the Frenzel technique, there's a few websites which describe it, try a search for Canadian freediver Eric Fattah, his site has a good description of it. You shouldn't actually swallow any air with it, you are using the tongue as a piston to push air into the ears. It is quite difficult to learn.

I'm no medic but I'd doubt padding stops will negate the effects of a shunt opening.

[Chris Bone]

I'm no doc either but belive a v.slow accent or very frequent stops might help more than longer stops. I think the problem with PFO is that small bubble in the venous blood strean shunt via the PFO into the artirial blood stream instead of being filtered by the lungs. So it follows that by reducing small bubbles in the venous blood stream the chance of DCI can be reduced.

[Foggy]

Again I'm no Doc,

but all the above seems good advice. Also spend some time on the surface before climbing into the boat (tell the skipper and others this is what you plan); hand off as much kit as possible before getting back onto the boat (an understanding buddy helps); use boats with lifts; stay on O2 as long as possible (take advice on how long )

Do NOT deny any symptoms, tell everyone

Hope that helps, dive safe

Paul

[Hellvet]

Thanks for the opinions so far - don't worry - i'm not going to sea dive anyway before i see Dr Wilmshurst next week, but i'm just trying to see if there is any theory behind these opinions as to "padding" my stops, cos if i can keep diving till i get it fixed i obviously want to minimise the risks of getting bent!

In answer to a previous question i am currently a BSAC ocean diver with a no stop dive limit and a depth limit to 20m, plus a medical certificate restriction to 20m, nitrox on air tables, slow ascents, and 1dive/day. The DDRC set these limits and have assumed a shunt when setting them. I am training as a Sports diver, but am not going to do any of the training which involves exertion, until cleared to do so!

I have been recommended by various people to do things such as no exertion after diving, avoid carrying kit, breathe nitrox for as long as possible on the surface, don't push dive times, don't get cold, and pad my stops.

No-one seems to want to give me any theory as to how and why to pad my stops though, other than saying its a good idea - my feeling is that i would stay as long as possible at my "ordinary" stops, extending their length rather than adding extra stops at deeper depth, but i'm not sure why or if this is any better than adding in deep stops?!

I know i will continue to off-gas at the surface, and better if i continue to breathe nitrox, but am just wondering if its better to add a few deeper stops to assist with off gassing by giving a less steep bubble gradient on the ascent, by slowing the ascent, or to increase the time spent off gassing at each depth.

I am not going to dive in the sea until i see Dr Wilmshurst anyway as its only another week, and i'm ok waiting now i can at least dive in the pool! Hopefully he'll have some advice as to whether one is better than the other...

Thanks anyway,
Helen

[Paul Oliver]

The time on the surface before getting out of the water and maintaining the use of a rich nitrox during the ladder climb and for the first 5 min on the boat are big factors in helping you here.

Also very important to stay hydrated - use an isotonic drink, try something like this one:-

http://www.harris-active.co.uk/isostarframe.htm

Try adding a 3 min stop at 3m, makes me feel a lot better

Mild fining actions while doing the safety stops also help off gassing (keep the blood moving )

HTH