Quiz - Physiology - Carbon Monoxide

Carbon monoxide in breathing air can lead to hypoxia because:

  • a. It causes involuntary hyperventilation

    Votes: 0 0.0%
  • b. hemoglobin bonds with CO 200 times more readily than with O2, which results in fewer red blood ..

    Votes: 73 97.3%
  • c. it has a strong oder and taste

    Votes: 0 0.0%
  • d. all the above are correct

    Votes: 2 2.7%

  • Total voters
    75

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Pedro Burrito

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We had an interesting discussion yesterday regarding CO. In light of that, here is another question from the PADI Dive Theory exam.

I will post a daily question from my exams to help newer divers and to encourage more experienced divers to interact gracefully and helpfully with the newer divers.

Reminder - this is a post in the Basic Forum and it is a green zone. Please be nice and on topic.

Thank you for your patience while we try to give people something to discuss other than Covid-19 and/or Politics. I will post the answer covered by the spoiler tag later today.
 
Hi Pedro,

Will you please describe different ways CO becomes present in a tank of breathing gas?

Specifically, are the questions below poor assumptions or good assumptions:
  1. used-up filters on the compressor system?
  2. poor placement of the compressor's intake?
  3. A new source of pollution next to the intake?
  4. PP blending with hydrocarbons present?
  5. A worn or malfunctioning compressor pump?

Can hydrocarbons in a tank, that is then partial pressure blended, cause CO in the tank?

If so, what is the chemical process that occurs to create the byproduct of CO?

How often is CO, either minor trace amounts, or critical amounts that could cause a medical intervention in tanks?

I know for many pros and self-described pros on SB, these are basic questions. I am prepared for their vitriol. I would like to review the ways CO enters a tank (yeah, I know, Google is my friend, that statement will be used I am sure).

Please don't link to a past thread. Those threads were yesterday. Pedro's thread is today's thread.

I generally know some of the answers, but I would like clarity and to review this info. I hope @DandyDon gets involved.

cheers,
m²v2
 
BTW, interesting article on CO levels in breathing gas in the latest (to reach my house) Alert Diver. Probably on the DAN web site too for you modern kids.
 
The answer is b. hemoglobin bonds with carbon monoxide 200 times more readily than with oxygen, which results in fewer red blood cells to transport oxygen.

Thank you for participating and look for the next question tomorrow. We have had some really interesting suggestions for better questions which we will ask soon.
 
Hi Pedro,

Will you please describe different ways CO becomes present in a tank of breathing gas?

Specifically, are the questions below poor assumptions or good assumptions:
  1. used-up filters on the compressor system?
  2. poor placement of the compressor's intake?
  3. A new source of pollution next to the intake?
  4. PP blending with hydrocarbons present?
  5. A worn or malfunctioning compressor pump?

Can hydrocarbons in a tank, that is then partial pressure blended, cause CO in the tank?

If so, what is the chemical process that occurs to create the byproduct of CO?

How often is CO, either minor trace amounts, or critical amounts that could cause a medical intervention in tanks?

I know for many pros and self-described pros on SB, these are basic questions. I am prepared for their vitriol. I would like to review the ways CO enters a tank (yeah, I know, Google is my friend, that statement will be used I am sure).

Please don't link to a past thread. Those threads were yesterday. Pedro's thread is today's thread.

I generally know some of the answers, but I would like clarity and to review this info. I hope @DandyDon gets involved.

cheers,
m²v2
I'm going to ask our CO expert, @DandyDon , to answer this please.
 
I don't recall this question being covered in my PADI OW or AOW course. However they were a year ago, so I might have just forgotten. This question is covered on some detail in Mark Powell's Deco for Divers, which I have been reading and re-reading over the last couple months. Interesting stuff :)

From what I have read, CO2 is primarily responsible for one of body's urge to breathe. One of the incorrect answers in the poll sounds it could be a symptom of breathing a gas with a high presence of CO2 (a). Is this true? And if so, what factors can cause a high partial pressure of CO2? I have heard of the following; are they true, and have I missed some important ones?
1) Skip-breathing (aka holding one's breath). Pausing after the inhale/exhale rather than breathing continuously can inhibit the body's ability to diffuse CO2 out through the lungs.
2) Shallow breathing. There is a volume of air that goes from our face (nose, sinuses, mouth, windpipe) down into the lungs. Whenever we breathe in, fresh gas comes in through the upper volume before reaching the lungs; conversely when we breathe out, the upper volume is exhausted before the gas in the lungs. However, gas exchange only occurs in the lungs, not the upper volume. When we breath shallowly, the upper volume may not be fully circulated out of the body, which inhibits the lungs' ability to exchange gas effectively. This is the dead space effect and can create lots of problems (O2 intake, CO2 and N2 exhaust).
3) Rebreathers with insufficient sorb. Rebreathers work by extracting ("scrubbing") CO2 from the gas we exhale, and inserting new O2, so that the gas will be safe to breathe. If the system is unable to scrub enough CO2, then it will build up over time, since we will exchange CO2 out of the lungs with each breath.
 
Hydrocarbons generating CO are normally found in the compressor oil being partially burned due to wear and failure of sealing surfaces.

While hydrocarbons in the tank can lead to partial combustion that could cause CO to be generated the main risk with partial pressure blending is the hydrocarbons would be a source of ignition for the oxygen present which could lend itself to ignition of things not normally considered fuel sources or "rapidly oxidize" things such as the tank itself. Oxygen fires tend be rapid and explosive in nature. That is why if partial pressure blending nitrox maintaining oxygen clean equipment and tanks is such a priority.
 
I don't recall this question being covered in my PADI OW or AOW course. However they were a year ago, so I might have just forgotten. This question is covered on some detail in Mark Powell's Deco for Divers, which I have been reading and re-reading over the last couple months. Interesting stuff :)

From what I have read, CO2 is primarily responsible for one of body's urge to breathe. One of the incorrect answers in the poll sounds it could be a symptom of breathing a gas with a high presence of CO2 (a). Is this true? And if so, what factors can cause a high partial pressure of CO2? I have heard of the following; are they true, and have I missed some important ones?
1) Skip-breathing (aka holding one's breath). Pausing after the inhale/exhale rather than breathing continuously can inhibit the body's ability to diffuse CO2 out through the lungs.
2) Shallow breathing. There is a volume of air that goes from our face (nose, sinuses, mouth, windpipe) down into the lungs. Whenever we breathe in, fresh gas comes in through the upper volume before reaching the lungs; conversely when we breathe out, the upper volume is exhausted before the gas in the lungs. However, gas exchange only occurs in the lungs, not the upper volume. When we breath shallowly, the upper volume may not be fully circulated out of the body, which inhibits the lungs' ability to exchange gas effectively. This is the dead space effect and can create lots of problems (O2 intake, CO2 and N2 exhaust).
3) Rebreathers with insufficient sorb. Rebreathers work by extracting ("scrubbing") CO2 from the gas we exhale, and inserting new O2, so that the gas will be safe to breathe. If the system is unable to scrub enough CO2, then it will build up over time, since we will exchange CO2 out of the lungs with each breath.
Hey just wanted to point out that CO2 and CO are not the same thing.

The excerpt you quoted is for CO2, not CO.
 
Hey just wanted to point out that CO2 and CO are not the same thing.

The excerpt you quoted is for CO2, not CO.
Right, thanks for pointing that out. Maybe I could have been more clear about that in my first post. One of the incorrect answers in the OP was "a. It causes involuntary hyperventilation". Which sounds like a CO2 issue to my ear.

This got me thinking about CO2 issues and hence the spooler tagged part of that post. On second thought, that's off topic and could probably use its own thread.
 
I am prepared for their vitriol.
And I'm prepared to take that out. :D :D :D

I've been poisoned twice. Both times I believe that it was from PPB in a dirty tank.
 
https://www.shearwater.com/products/swift/

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