Breaks

Drmike · 7th June 2006, 04:03

Quote: (Originally Posted by Steve)

I’m preparing a dive plan for a quite deep and therefore quite a long dive. Without getting bogged down in the actual dive plan there is a deco (time) need for a setpoint of 1.3 or 1.4 and as a result the CNS clock hits about 300%.

Assuming that on this dive one could easily be on a setpoint of 1.4 for 9 hours what are peoples theories on ‘air breaks’? When I say air breaks I am referring to the concept of taking a break from typically breathing 100% O2 for extended periods. I’m thinking about transferring that line of reasoning to a whole CCR dive.

To my non medically trained brain it seems reasonable that if we should take an air break when breathing O2 for long periods then there still exists a need to have a break from a pO2 of 1.4 after a certain amount of time. If this is the case, what should the break schedule look like?

I dont bother with breaks if the setpoint is 1.3.

No theory behind it- Its just what Ive always done.

On the 191m dive 8 hours of deco, around 6 hours was spent at 1.3, no air breaks.

It made very little difference decoing out at 1.3 or 1.4 for this dive so I chose the lower setpoint so as to have less of a problem with it.

But like I said I have no facts to back it up.

**Steve** · 7th June 2006, 04:15

Any irritation of the lungs on that dive Mike? I get a bit of a dry cough after 3 hours. AB tells me that sorb may have a part to play as well as the O2.

Drmike · 7th June 2006, 06:23

Quote: (Originally Posted by Steve)

Any irritation of the lungs on that dive Mike? I get a bit of a dry cough after 3 hours. AB tells me that sorb may have a part to play as well as the O2.

None at all.

I find if I do any more than an hour on 1.6 I can feel it, but on long hangs on 1.3 Ive never felt any irritation.

Hardly scientific though.

abowie · 7th June 2006, 08:57

Quote: (Originally Posted by Steve)

Any irritation of the lungs on that dive Mike? I get a bit of a dry cough after 3 hours. AB tells me that sorb may have a part to play as well as the O2.

To expand on this.

In anaesthesia we use HME filters that are effective enough to remove virus sized particles from circuit gas. I honestly don't know how much fine particulate sorb actually ends up in your lungs diving a Rebreather but I'd bet that it is more than none. Sorb in your eye hurts (done that). Sorb on your bronchial mucosa will undoubtable make you cough even in very small amounts.

The other likely culprits that may irritate your lungs would be nebulised water (you'll always get some even on an Rebreather), other "crud" from inside your loop, and of course O2 toxicity effects on your lungs.

7th June 2006, 04:03	#11 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,322	Re: Breaks Quote: (Originally Posted by Steve) I’m preparing a dive plan for a quite deep and therefore quite a long dive. Without getting bogged down in the actual dive plan there is a deco (time) need for a setpoint of 1.3 or 1.4 and as a result the CNS clock hits about 300%. Assuming that on this dive one could easily be on a setpoint of 1.4 for 9 hours what are peoples theories on ‘air breaks’? When I say air breaks I am referring to the concept of taking a break from typically breathing 100% O2 for extended periods. I’m thinking about transferring that line of reasoning to a whole CCR dive. To my non medically trained brain it seems reasonable that if we should take an air break when breathing O2 for long periods then there still exists a need to have a break from a pO2 of 1.4 after a certain amount of time. If this is the case, what should the break schedule look like? I dont bother with breaks if the setpoint is 1.3. No theory behind it- Its just what Ive always done. On the 191m dive 8 hours of deco, around 6 hours was spent at 1.3, no air breaks. It made very little difference decoing out at 1.3 or 1.4 for this dive so I chose the lower setpoint so as to have less of a problem with it. But like I said I have no facts to back it up. __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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7th June 2006, 04:15	#12 (permalink)
Steve Ladies bring a plate Current Rebreather/s: Megalodon Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Sport Kiss Classic Kiss MK 15.X Home Build Join Date: Feb 2005 Location: Perth - Australia Posts: 1,116	Re: Breaks Any irritation of the lungs on that dive Mike? I get a bit of a dry cough after 3 hours. AB tells me that sorb may have a part to play as well as the O2. __________________ WARNING: I contain occasional coarse language, extreme sexual references, nudity, and adult themes, which may offend some people - Usually churchy types.
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7th June 2006, 06:23	#13 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,322	Re: Breaks Quote: (Originally Posted by Steve) Any irritation of the lungs on that dive Mike? I get a bit of a dry cough after 3 hours. AB tells me that sorb may have a part to play as well as the O2. None at all. I find if I do any more than an hour on 1.6 I can feel it, but on long hangs on 1.3 Ive never felt any irritation. Hardly scientific though. __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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7th June 2006, 08:57	#14 (permalink)
abowie Fighting Girl Current Rebreather/s: Sport Kiss Other Rebreather/s: Join Date: May 2005 Location: Land of Oz Posts: 574	Re: Breaks Quote: (Originally Posted by Steve) Any irritation of the lungs on that dive Mike? I get a bit of a dry cough after 3 hours. AB tells me that sorb may have a part to play as well as the O2. To expand on this. In anaesthesia we use HME filters that are effective enough to remove virus sized particles from circuit gas. I honestly don't know how much fine particulate sorb actually ends up in your lungs diving a Rebreather but I'd bet that it is more than none. Sorb in your eye hurts (done that). Sorb on your bronchial mucosa will undoubtable make you cough even in very small amounts. The other likely culprits that may irritate your lungs would be nebulised water (you'll always get some even on an Rebreather), other "crud" from inside your loop, and of course O2 toxicity effects on your lungs. __________________ Andrew Bowie Rebreather-friendly Buddy
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