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Thread: Hyperventilation Versus C02 lung retention.

  1. #1
    New Member Brett B Hemphill will become famous soon enough Brett B Hemphill will become famous soon enough Brett B Hemphill will become famous soon enough Brett B Hemphill will become famous soon enough Brett B Hemphill's Avatar
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    Hyperventilation Versus C02 lung retention.

    Ok time to play the devils advocate here.

    Iíve read and listened to a lot of the subject mater concerning C02 lung retention and the myriad of variables which may cause it.

    Iíve always believed it its nearly impossible hyperventilate on a OC demand valve, but based on normal ambient CCR breathing designs and what Iíve seen, isnít it possible that panicked short shallow breathing leading to hyperventilation may have been the cause in some re-breather fatalities.

    If this is a possibility is there a post mortem test that could be used to detect levels 02 and C02 in lung tissue and assess there value prior to death.

    All input welcome.

    TY:

    Brett B Hemphill


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    Re: Hyperventilation Versus C02 lung retention.

    Quote Originally Posted by Brett B Hemphill  View Original Post
    Ok time to play the devils advocate here.

    Iíve read and listened to a lot of the subject mater concerning C02 lung retention and the myriad of variables which may cause it.

    Iíve always believed it its nearly impossible hyperventilate on a OC demand valve, but based on normal ambient CCR breathing designs and what Iíve seen, isnít it possible that panicked short shallow breathing leading to hyperventilation may have been the cause in some re-breather fatalities.

    If this is a possibility is there a post mortem test that could be used to detect levels 02 and C02 in lung tissue and assess there value prior to death.

    All input welcome.

    TY:

    Brett B Hemphill

    Although I am pretty dumb in this area, it seems to me that short, shallow breathing would lead to CO2 retention from not clearing out the lungs.
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    Re: Hyperventilation Versus C02 lung retention.

    Quote Originally Posted by Brett B Hemphill  View Original Post
    Ok time to play the devils advocate here.

    Iíve read and listened to a lot of the subject mater concerning C02 lung retention and the myriad of variables which may cause it.

    Iíve always believed it its nearly impossible hyperventilate on a OC demand valve, but based on normal ambient CCR breathing designs and what Iíve seen, isnít it possible that panicked short shallow breathing leading to hyperventilation may have been the cause in some re-breather fatalities.

    If this is a possibility is there a post mortem test that could be used to detect levels 02 and C02 in lung tissue and assess there value prior to death.

    All input welcome.

    TY:

    Brett B Hemphill

    Everything is possible.
    This worlds atmosphere is not much different from either an OC demand valve
    nor a CCR.
    You may hyperventilate from both. It does not matter wether your metabolized CO2 vanishes into space, or into cat litter.

    Matthias

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    Re: Hyperventilation Versus C02 lung retention.

    Quote Originally Posted by Brett B Hemphill  View Original Post
    Ok time to play the devils advocate here.

    Iíve always believed it its nearly impossible hyperventilate on a OC demand valve, but based on normal ambient CCR breathing designs and what Iíve seen, isnít it possible that panicked short shallow breathing leading to hyperventilation may have been the cause in some re-breather fatalities.

    If this is a possibility is there a post mortem test that could be used to detect levels 02 and C02 in lung tissue and assess there value prior to death.
    The short answer is no. There is no post-mortem test that will reliably indicate pre-mortem levels of CO2. The same is true for O2.

    One reason (amongst many) is that the process of death is not instantaneous and metabolic processes do not become frozen when a person dies. In drowning, which is almost always the final common pathway in underwater accidents, all body tissues are deprived of oxygen and the means to rid themselves of CO2. So any derangements in O2 and/or CO2 that are the cause of the accident are completely swamped by the result, that is, tissue asphyxia.

    My feeling is that rebreather 'black box flight recorders' are probably the way forward.

    I am sure that you are correct in that short shallow breathing may lead to retained CO2. You may remember Simon Mitchell's excellent presentation in Marianna in May, which covered this pretty well.

    Andy


    Andy

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    Re: Hyperventilation Versus C02 lung retention.

    I think we're using the term hyperventilation incorrectly.

    Clinically, hyPERventilation provides INCREASED lung ventilation. This actually drops your blood levels of CO2. This is used in free diving to increase ones breath hold capacity, or in the ED we see this, and people develop tingling and sometimes pass out.

    What happens in RB diving is hyPOventilation. This is from not exchanging enough gas in the lungs from shallow breathing, or increased breathing resistance. This leads to CO2 retension, this downward spiral of fatigue and in the unfortunate case of David Shaw, death.

    Ventilation refers to gas movement. Fast, shallow breathing could cause hyPER or hyPOventilation.

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    Re: Hyperventilation Versus C02 lung retention.

    Quote Originally Posted by apitkin  View Original Post
    My feeling is that rebreather 'black box flight recorders' are probably the way forward.

    I am sure that you are correct in that short shallow breathing may lead to retained CO2. You may remember Simon Mitchell's excellent presentation in Marianna in May, which covered this pretty well.
    I have been very interested in the CO2 retention aspects of RB fatalities. I don't believe a black box will detect results of hyperventilation since the concentration of CO2 will appear in and near the DSV and black box information is likely to be gathered at the control unit. For instance a mushroom valve failure will short circuit the breathing loop resulting in high CO2 and low O2 in the affected breathing hose but not in the main section of the RB.
    The other issue with autopsy detection is it is my understanding most corpses will have a low blood O2 concentration due to the fact that they stopped breathing.
    Cheers,

    Dave....

    www.wedivebc.com

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    Re: Hyperventilation Versus C02 lung retention.

    Observation on CO2:

    This is just an example of a problem dive I had once.


    I was diving my KISS Classic in a volcano in Guatemala. The water temp was around 65 degrees and I was wearing a 5mm suit, and hood.

    On a typical dive as we were searching for Mayan artifacts, I became self aware that my breathing had increased and I was having a slight headache. Because of this I switched off the loop and onto OC. Of course the problem went away, thus I knew something was going on with the unit not scrubbing properly.

    Now this is where the real problem came in:

    I had already obtained over 45 minutes of required decompression. First thing I noticed when I switched to OC was the decreased breathing gas temperature. I than set down on a rock at 80 feet for my deep stop and switch my VR3 from CCR to OC air (the only bailout gas and diluent available in the volcano). BAM, my required deco climbed from 45 to over 70 minutes. Within 10 minutes, the cold diluent quickly gave me the shivers, so I decided I could never make 60 more minutes without freezing, so I went back on the loop and attempted to maintain the 1.2-1.3 PO2 until I hit 20 and could switch to oxygen. (the only other gas we had in the volcano). During the decompression I did notice that it helped if I squeezed the loop on exhalation and let it go in inhalation, making the gas go around the loop.

    Lucky for me I was side mounting an aluminum 80 of Oxygen and an aluminum 80 of air, no back mounted tanks available in a volcano. Thus I had plenty of gas to drain and flush the unit multiple times with air and then jack the O2 back up until I hit 20 feet.

    After exiting the dive and examining my equipment, I found I had broken a mushroom valve on the inhalation side, just as I had suspected.

    The main point about this is, during the dive, I noticed (without fancy gadgets) the change in my own personal breathing pattern because of the build up of CO2.
    Last edited by Curt Bowen; 26th November 2008 at 03:10.

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    Re: Hyperventilation Versus C02 lung retention.

    Quote Originally Posted by Curt Bowen  View Original Post
    Observation on CO2:

    This is just an example of a problem dive I had once.

    After exiting the dive and examining my equipment, I found I had broken a mushroom valve on the inhalation side, just as I had suspected.

    The main point about this is, during the dive, I noticed (without fancy gadgets) the change in my own personal breathing pattern because of the build up of CO2.
    Seems I had the same or very close experience....

    http://www.rebreatherworld.com/showthread.php?t=18229

    John

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    Re: Hyperventilation Versus C02 lung retention.

    Hyperventilation: A state in which there is an increased amount of air entering the pulmonary alveoli (increased alveolar ventilation), resulting in reduction of carbon dioxidetension and eventually leading to alkalosis. An increased depth and rate of breathing greater than demanded by the body needs; can causedizziness and tingling of the fingers and toes. Seizures, irregular heart beats, and (muscle spasms so severe that the muscle locks in a rigid position) can result from severe respiratory alkalosis. An increase in the rateor shallow breathing, which reducesthe concentration of co2in the arteries which can lead to dizzinessand if prolonged, loss of consciousness.

    Respiratory Alkalosis: An alkali imbalance in the body caused by a lower-than-normal level of carbon dioxide in the blood. In the lungs, oxygen from inhaled air is exchanged for carbon dioxide from the blood. This process takes place between the alveoli (tiny air pockets in the lungs) and the blood vessels that connect to them. When a person hyperventilates, this exchange of oxygen for carbon dioxide is speeded up, and the person exhales too much carbon dioxide. This lowered level of carbon dioxide causes the pH of the blood to increase, leading to alkalosis.

    Hypoventilation: An abnormal condition of the respiratory system, characterized by increased carbon dioxide arterial tension, and generalized decreased respiratory function. Eventualy leading to respiratory acidosis, hypoventilation occurs when the volume of air that enters the alveoli and takes part in gas exchanges is not adequate for the metabolic needs of the body.

    Respiratory Acidosis: A condition in which a build-up of carbon dioxide in the blood produces a shift in the body's pH balance and causes the body's system to become more acidic. This condition is brought about by a problem either involving the lungs and respiratory system or signals from the brain that control breathing.

    Respiratory acidosis is an acid imbalance in the body caused by a problem related to breathing. In the lungs, oxygen from inhaled air is exchanged for carbon dioxide from the blood. This process takes place between the alveoli (tiny air pockets in the lungs) and the blood vessels that connect to them. When this exchange of oxygen for carbon dioxide is impaired, the excess carbon dioxide forms an acid in the blood. The condition can be acute with a sudden onset, or it can develop gradually as lung function deteriorates.

    The most notable symptom will be slowed or difficult breathing. Headache, drowsiness, restlessness, tremor, and confusion may also occur. A rapid heart rate, changes in blood pressure, and swelling of blood vessels in the eyes may be noted upon examination. This condition can trigger the body to respond with symptoms of metabolic alkalosis, which may include cyanosis, a bluish or purplish discoloration of the skin due to inadequate oxygen intake. Severe cases of respiratory acidosis can lead to coma and death.

    Here is the question, although I completely believe that resistance of breathing is a primary factor in CO2 retention in the lung tissue, especially concerning forced exhalation.
    But I have to wonder if stressed rapid breathing and some possible initial hyperventilation may also be a possibility, or even a catalyst toward the eventual shallow short breathing which may cause the opposite which is CO2 retention?

    Just PonderingÖ
    Brett

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    50's research... still good stuff...

    Some of you might enjoy reading through these:

    Lanphier and Camporesi describe Lanphier's (1-4) work at NEDU to answer the question 'why don't divers breathe enough?'

    Quote Originally Posted by Lanphier and Camporesi. Chapter 5. Respiration and Exertion, In: The Physiology and Medicine of Diving
    1. Higher Inspired Oxygen (PiO2) at 4 ata (404 kPa) accounted for not more than 25% of the elevation in End Tidal CO2 (etCO2) above values found at the same work rate when breathing air just below the surface.
    2. Increased Work of Breathing accounted for most of the elevation of PACO2 (alveolar gas equation) in exposures above 1 ata (101 kPa), as indicated by the results when helium was substituted for nitrogen at 4 ata (404 kPa).
    3. Inadequate ventilatory response to exertion was indicated by the fact that, despite resting values in the normal range, PetCO2 rose markedly with exertion even when the divers breathed air at a depth of only a few feet.
    References:
    1. Lanphier. Nitrogen-Oxygen Mixture Physiology, Phases 1 and 2. NEDU Report 1955-07. RRR ID: 3326
    2. Lanphier, Lambertsen, and Funderburk. Nitrogen-Oxygen Mixture Physiology - Phase 3. End-Tidal Gas Sampling System. Carbon Dioxide Regulation in Divers. Carbon Dioxide Sensitivity Tests. NEDU Report 1956-02. RRR ID: 3327
    3. Lanphier. NITROGEN-OXYGEN MIXTURE PHYSIOLOGY. PHASE 4. CARBON DIOXIDE SENSITIVITY AS A POTENTIAL MEANS OF PERSONNEL SELECTION. PHASE 6: CARBON DIOXIDE REGULATION UNDER DIVING CONDITIONS NEDU Report 1958-07. RRR ID: 3362
    4. Lanphier. Nitrogen-Oxygen Mixture Physiology. Phase 5. Added Respiratory Dead Space (Value in Personnel Selection tests) (Physiological Effects Under Diving Conditions). NEDU Report 1956-05. RRR ID: 3809



    Please check this out!
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