CO2 Levels

[Phil C]

Anyone done any end tidal CO2 measurements for inhale and exhale dives?

Also interested in any experience other divers may have had in physiological responses to high CO2 eg tremor.

Phil C

 

[watts]

We did lots of o2 full lung and frc sampling with seb in 05 finding that most divers had higher 02 after frcs in exhaled breath after dive. Havnt done co2 samples though.I think Eric has done so.
During full exhale statics I get co2 tremors and twitches alot.

 

[efattah]

I used to have an accurate capnograph. Usually my contraction threshold was around 6.0 to 7.0% CO2. I noticed tremors would start around 9.0% and CO2 narcosis would start around 9.5%-10%. The highest I ever withstood was 11% and felt a CO2 blackout was imminent.

 

[Phil C]

Hi Eric,

Sounds like the kind of data I was looking for.

With the Capnograph are you measuring end tidal CO2?

How long after the commencement of tremors did you manage to continue the hold?

How long did the tremors take to stop after you started respiring again?

Did you ever try monitoring the C02 on an exhale - if so, how did you carry out the measurement? eg forced exhale after holding on passive?

Phil C

Phil

 

[efattah]

Hi Eric,

Sounds like the kind of data I was looking for.
With the Capnograph are you measuring end tidal CO2?
How long after the commencement of tremors did you manage to continue the hold?
How long did the tremors take to stop after you started respiring again?
Did you ever try monitoring the C02 on an exhale - if so, how did you carry out the measurement? eg forced exhale after holding on passive?
Phil C
Phil

I was measuring end tidal CO2.
During pure O2 statics, I can continue holding my breath long after the tremors begin. During air CO2 tables, tremors only occurred during the highest levels of CO2. During these tables I was not holding to the limit but doing 2 - 2.5 minute statics spaced by 1 breath. So I don't know how long I could hold the tremors for.
I didn't do any FRC CO2 measurements, the capnograph broke down before I started FRC experiments.

 

[hogphish]

I was measuring end tidal CO2.
During pure O2 statics, I can continue holding my breath long after the tremors begin. During air CO2 tables, tremors only occurred during the highest levels of CO2. During these tables I was not holding to the limit but doing 2 - 2.5 minute statics spaced by 1 breath. So I don't know how long I could hold the tremors for.
I didn't do any FRC CO2 measurements, the capnograph broke down before I started FRC experiments.

How do you get a meaningful end tidal co2 with an frc breathold. Your first post hold ventilation is an inspiration. I would like to see the results of an arterial line study. This would provide the best accuracy and most meaningful data.

 

[efattah]

How do you get a meaningful end tidal co2 with an frc breathold. Your first post hold ventilation is an inspiration. I would like to see the results of an arterial line study. This would provide the best accuracy and most meaningful data.

At FRC you can still exhale about three litres, more than enough for an end tidal CO2 measurement. Otherwise you can use a transcutaneous monitor.