Bends on Heliox..

Padowan · 4th August 2005, 08:59

Following on from another discussion about He and N2 bends and the treatment thereof, I have a question.

When diving trimix, if you get a bend, it might be a He bend, it might be a N2 bend, it could be a bit of both. Now, in the case of a N2 bend, going onto Oxygen makes sense as you are now maximising the N2 gradient across the lungs. For a purely Helium bend O2 does not seem to make sense for the same reason as you will have the same He gradient across the lungs whether you breathe O2 or air as the He content in air is negligible. But perhaps if you're diving Trimix, and you reckon it's a He bend, you might have an N2 bend too, so perhaps going onto O2 is a wise precautionary measure, and it will have the benefit of speeding up the offgas of the residual N2 loading.

So, now you're diving on Heliox, there is no N2. If you have a bend, it is only gonna be a He bend, so does going onto O2 make sence, as in my mind, you will get no more offgas benefit breathing O2, than you will just breathing air.

Is O2 prescribed for bends for another reason other than maximising the N2 gradient across the lungs?

What are peoples thoughts, and please explain.
* All of the above is talking about treatment on the boat, not in a pot where we can recompress bubbles.

PeteS · 4th August 2005, 09:42

Well in my humble opinion......

The tissues that had the bubble suffered trauma. The O2 will help them to heal. High pressure O2 helps them to heal quicker. So recompression days after the event can still be beneficial.

Only my opinion......

Scuba_Vixen · 4th August 2005, 09:45

It's not about maximizing the inert gas gradient that O2 is used for DCS treatment.

You already had wayyy too much gradient, that's why you're fricken' bent.

Bubbles impeed blood flow and hence O2 that the cells need to stay healthy. Any way you can get O2 thru your body is a good thing. Blood flow is the vehicle that transports all that nasty inert gas back out of you.

Breathing O2 also creates a higher partial pressure deficit than an inspired mix with some inert component.

With an inert component, what goes in has to come back out. Since O2 is metabolised, and the resulting CO2 has a lower partial pressure than the O2 did, it's that partial pressure deficit that makes room for the gas bubbles to come out.

Ther'e's sure to be a more complete and detailed answer coming from some one, but that's a start.

Darlene

lizardland · 4th August 2005, 13:05

As everyone says, there are many more mechanisms other than just a gas gradient at issue. HBO treatment has many, many benefits.

pchanning · 4th August 2005, 16:22

Whilst o2 is a vasoconstrictor, it: "refreshes the parts other gases cannot reach". A bit like Heineken IIRC

The difference is o2, unlike Heineken, seems to do it straight off.

Barrie Law · 4th August 2005, 16:23

During some deeper dives on Heliox I have felt slightly 'off' for no reason and going on the 02 on the boat for a few minutes has cleared things, If you had a Bend after diving Heliox you would have to follow the standard guidelines for a Bend and get of to the pot I would suspect you will be treated as if you had dived Trimix by the chamber staff, I am not aware of any specific Heliox recompression tables.

Cheers

ROB DAVIE · 5th August 2005, 00:27

"Bubble Trouble" as Dick Rutkowski termed it, is still bubble trouble.

Your two most important responses are (1) squeeze the bubbles back down to a smaller size, so they won't cause so much trouble, and (2) increase both oxygen fraction (100%) and pressure, so as to get as much O2 into the blood and therefore out to the tissues as possible.

In the pot it is easy. Put an O2 hat or mask on the patient. Run 100% O2 into that, and press him down to 60 fsw with air in the chamber. A dry, resting patient can tolerate higher PO2's, and if he or she convulses, a simple temporary removal of the mask or hat will stop it in moments.

Cheers!

Rob Davie
DMT

Barrie Law · 5th August 2005, 00:37

Rob
Do you have any info on the number of divers who have been bent on Heliox?

Cheers

ROB DAVIE · 5th August 2005, 01:00

Barrie,

DAN might have some figures on that and possibly Dick Rutkowski. I don't happen to have any sources for numbers on that. Sorry.

Barrie Law · 5th August 2005, 02:20

Rob
No problem, I was just curious about the incident rate with Heliox.
I will try DAN as you suggest.

Cheers

4th August 2005, 08:59	#1 (permalink)
Padowan Proper Boffin Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: Kent, UK. Posts: 518	Bends on Heliox.. Following on from another discussion about He and N2 bends and the treatment thereof, I have a question. When diving trimix, if you get a bend, it might be a He bend, it might be a N2 bend, it could be a bit of both. Now, in the case of a N2 bend, going onto Oxygen makes sense as you are now maximising the N2 gradient across the lungs. For a purely Helium bend O2 does not seem to make sense for the same reason as you will have the same He gradient across the lungs whether you breathe O2 or air as the He content in air is negligible. But perhaps if you're diving Trimix, and you reckon it's a He bend, you might have an N2 bend too, so perhaps going onto O2 is a wise precautionary measure, and it will have the benefit of speeding up the offgas of the residual N2 loading. So, now you're diving on Heliox, there is no N2. If you have a bend, it is only gonna be a He bend, so does going onto O2 make sence, as in my mind, you will get no more offgas benefit breathing O2, than you will just breathing air. Is O2 prescribed for bends for another reason other than maximising the N2 gradient across the lungs? What are peoples thoughts, and please explain. * All of the above is talking about treatment on the boat, not in a pot where we can recompress bubbles. __________________ Padowan The future's bright, the future's Yellow .....for now padowan.net - Latest Video: Scapa Flow Rebreather Diving
(Online)

4th August 2005, 09:42	#2 (permalink)
PeteS Consent Issued! Current Rebreather/s: Inspiration Classic Inspiration Vision Other Rebreather/s: Join Date: Jun 2005 Location: New Zealand Posts: 533	Well in my humble opinion...... The tissues that had the bubble suffered trauma. The O2 will help them to heal. High pressure O2 helps them to heal quicker. So recompression days after the event can still be beneficial. Only my opinion...... __________________ Pete S. http://www.steggle.co.nz Every silver lining has a cloud
(Online)

4th August 2005, 09:45	#3 (permalink)
Scuba_Vixen e/mCCR Dolphin Pilot Current Rebreather/s: Other CCR Home Build Other Rebreather/s: Other CCR Home Build Join Date: May 2005 Location: St. Croix USVI Posts: 557	It's not about maximizing the inert gas gradient that O2 is used for DCS treatment. You already had wayyy too much gradient, that's why you're fricken' bent. Bubbles impeed blood flow and hence O2 that the cells need to stay healthy. Any way you can get O2 thru your body is a good thing. Blood flow is the vehicle that transports all that nasty inert gas back out of you. Breathing O2 also creates a higher partial pressure deficit than an inspired mix with some inert component. With an inert component, what goes in has to come back out. Since O2 is metabolised, and the resulting CO2 has a lower partial pressure than the O2 did, it's that partial pressure deficit that makes room for the gas bubbles to come out. Ther'e's sure to be a more complete and detailed answer coming from some one, but that's a start. Darlene
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4th August 2005, 13:05	#4 (permalink)
lizardland Yak Current Rebreather/s: MK 15.X Home Build Other Rebreather/s: Classic Kiss Home Build Join Date: Mar 2005 Location: North... Posts: 1,304	As everyone says, there are many more mechanisms other than just a gas gradient at issue. HBO treatment has many, many benefits.
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4th August 2005, 16:22	#5 (permalink)
pchanning PFO free :) Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: fixed! Posts: 454	An Idiots Guide... Whilst o2 is a vasoconstrictor, it: "refreshes the parts other gases cannot reach". A bit like Heineken IIRC The difference is o2, unlike Heineken, seems to do it straight off. __________________ Cheers Paul The key to enlightenment... is survival.
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4th August 2005, 16:23	#6 (permalink)
Barrie Law RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jun 2005 Location: Ireland Posts: 459	Bends on Heliox.. During some deeper dives on Heliox I have felt slightly 'off' for no reason and going on the 02 on the boat for a few minutes has cleared things, If you had a Bend after diving Heliox you would have to follow the standard guidelines for a Bend and get of to the pot I would suspect you will be treated as if you had dived Trimix by the chamber staff, I am not aware of any specific Heliox recompression tables. Cheers __________________ Barrie Law Rebreather World Store Supplying the Rebreather World Tel:US +19548403892 Fax:US+19543333792 Tel:EU+442071930496 Fax:EU+442077606344 Mobile+353876880628 Skype:barrielaw Email: barrie@rebreatherworldstore.com
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5th August 2005, 00:27	#7 (permalink)
ROB DAVIE Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: HOUSTON, REPUBLIC OF TEJAS Posts: 1,120	"Bubble Trouble" as Dick Rutkowski termed it, is still bubble trouble. Your two most important responses are (1) squeeze the bubbles back down to a smaller size, so they won't cause so much trouble, and (2) increase both oxygen fraction (100%) and pressure, so as to get as much O2 into the blood and therefore out to the tissues as possible. In the pot it is easy. Put an O2 hat or mask on the patient. Run 100% O2 into that, and press him down to 60 fsw with air in the chamber. A dry, resting patient can tolerate higher PO2's, and if he or she convulses, a simple temporary removal of the mask or hat will stop it in moments. Cheers! Rob Davie DMT __________________ [SIZE=2]"CC Rebreathers will become a viable part of tech diving [U]WHEN PIGS FLY[/U]!!"--GI3[/SIZE]
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5th August 2005, 00:37	#8 (permalink)
Barrie Law RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jun 2005 Location: Ireland Posts: 459	Bends on Heliox.. Rob Do you have any info on the number of divers who have been bent on Heliox? Cheers __________________ Barrie Law Rebreather World Store Supplying the Rebreather World Tel:US +19548403892 Fax:US+19543333792 Tel:EU+442071930496 Fax:EU+442077606344 Mobile+353876880628 Skype:barrielaw Email: barrie@rebreatherworldstore.com
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5th August 2005, 01:00	#9 (permalink)
ROB DAVIE Administrator Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Feb 2005 Location: HOUSTON, REPUBLIC OF TEJAS Posts: 1,120	Barrie, DAN might have some figures on that and possibly Dick Rutkowski. I don't happen to have any sources for numbers on that. Sorry.
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5th August 2005, 02:20	#10 (permalink)
Barrie Law RebreatherWorld Sponsor Current Rebreather/s: Inspiration Classic Other Rebreather/s: Join Date: Jun 2005 Location: Ireland Posts: 459	Bends on Heliox.. Rob No problem, I was just curious about the incident rate with Heliox. I will try DAN as you suggest. Cheers __________________ Barrie Law Rebreather World Store Supplying the Rebreather World Tel:US +19548403892 Fax:US+19543333792 Tel:EU+442071930496 Fax:EU+442077606344 Mobile+353876880628 Skype:barrielaw Email: barrie@rebreatherworldstore.com
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