End tidal CO2 Monitoring

[jar546]

When we intubate a patient (breathing tube in the trachea) we monitor the CO2 that is expelled (exhaled) from the patient. This measurement is one of the most critical items that are monitored while the patient is intubated.

Is there any type of CO2 monitoring device that has its own gauge or can be incorporated into a dive computer?

There are different methods for monitoring end tidal CO2 and I would think that since the technology has been available for decades above the water, it would be possible to achieve this level of accuracy and importance below the water with rebreathers.

 

[Garth]

That's a strong claim that end tidal CO2 is the most important. Who are you, what do you do? Anesthesiologist, CRNA?

 

[TSandM]

I would agree that end tidal CO2 is one of the most important parameters monitored during surgery. Inadequate ventilation leads to acidosis, which can affect cardiac function and raises adrenaline levels. Hyperventilation affects O2 offloading in the tissues.

I'm not a rebreather person, but I did hear a rumor a year or so ago that there was some unit that was going to be marketed with a CO2 sensing setup. I guess it's been difficult to make it small enough and waterproof. It would certainly add some safety to using a rebreather.

 

[lemon]

my understanding is that it has been challenging to develop a useful CO2 monitor that is affordable and works reliably in the moist, humid loop environment.

 

[jar546]

That's a strong claim that end tidal CO2 is the most important. Who are you, what do you do? Anesthesiologist, CRNA?

You may want to read my post again. Not what I said. Communication breakdown Garth!

 

[Garth]

I read it thanks.

 

[TSandM]

I had an interesting conversation with Mel Clark last night. She is a technical diver, rebreather instructor, and author of two textbooks on rebreather diving. I asked her about CO2 monitoring. Her answer was thought-provoking. She said that CO2 does not increase in a linear fashion as the scrubber ages; it remains constant until the sorb is almost exhausted, and then climbs quite steeply.

It was her position that a CO2 sensor would actually REDUCE safety, because people would push their time on their sorb, waiting until the CO2 began to go up.

I'm not entirely convinced, as I think that a CO2 monitor could be useful in some types of unpredicted malfunctions (and overbreathing the scrubber) but it was an interesting take on the question, I thought.

 

[sea2summit]

I had an interesting conversation with Mel Clark last night. She is a technical diver, rebreather instructor, and author of two textbooks on rebreather diving.

Three Would have made an intro at the BBQ if I would have known a fellow SB'r was there.

Anyway back on topic. I think even though you go from nothing to breakthrough on a scrubber I still think it would be useful. I know a CCR diver that took a hit in a cave and had a pretty rough exit even after bailing out because of the residual effects, maybe if he had a warning after one breath it would have allowed him to exit without risking the whole team due to breathing their gas and his. But as has been pointed out no one's been able to consistently show accurate detection in the humid environment:depressed:

 

[jar546]

I had an interesting conversation with Mel Clark last night. She is a technical diver, rebreather instructor, and author of two textbooks on rebreather diving. I asked her about CO2 monitoring. Her answer was thought-provoking. She said that CO2 does not increase in a linear fashion as the scrubber ages; it remains constant until the sorb is almost exhausted, and then climbs quite steeply.

It was her position that a CO2 sensor would actually REDUCE safety, because people would push their time on their sorb, waiting until the CO2 began to go up.

I'm not entirely convinced, as I think that a CO2 monitor could be useful in some types of unpredicted malfunctions (and overbreathing the scrubber) but it was an interesting take on the question, I thought.

You can't fix stupid but there are apparently some cases where the diver was unaware that his/her CO2 levels were too high with a bad result.

If someone wants to use a CO2 monitor to get more life out of a scrubber, you can't stop them but knowledge of this measurement can save a life.

 

[sea2summit]

You can't fix stupid but there are apparently some cases where the diver was unaware that his/her CO2 levels were too high with a bad result.

If someone wants to use a CO2 monitor to get more life out of a scrubber, you can't stop them but knowledge of this measurement can save a life.

At 300' no amount of CO2 is tolerable to a diver. "I" think Mel's point is you go from 0 CO2 in the loop to a near fatal/fatal amount in a breath or two, in which case an alarm would not give you adequate time to respond.

It's not about stretching scrubber at all it makes no sense to dive longer because you have the alarm because then you would just be planning to switch to OC which depending on gas would be much more expensive than the sorb. I guess you could argue temp sticks allow divers to stretch sorb but not an alarm.