Blood gas studies on free divers.

[Grubby]

But now we are digressing off topic.
Thanks to all those for advice and assistance.

 

[efattah]

Grubby,

Are you more interested in lactate or acidity in general (i.e. carbonic acid?) Personally I have exhaled 11% CO2 into a capnograph after extreme CO2 tables, but these same tables likely did not produce much lactic acid. On the other hand, ascents from deep dives where peripheral circulation is virtually absent can produce repeated leg failures on the ascent from lactic acid, and in some cases the acid can take 48 hours to be cleared (a sign of the immense acid produced).

 

[Grubby]

I'd like to have a look at both really. The lactate would be great to be able to quantify the degree to I which divers dive in a shocked state. The reality is that with the peripheral vasoconstriction that occurs we do perform in an shocked state.
Carbonic acid would be great to see just how much build up in our blood streams.

 

[sebastien murat]

Let's get it clear: we do not dive in a shocked state. The state is not pathological, in which there is failure of physiologic regulation. Instead, it is a full y regulated and coordinated condition.

 

[Ronnie]

Let's get it clear: we do not dive in a shocked state. The state is not pathological, in which there is failure of physiologic regulation. Instead, it is a full y regulated and coordinated condition.

I agree that shock is a misleading term to use. Deep divers do employ a low cardiac output mode but as you say, shock is a pathological physiological state.

 

[Grubby]

My humblest apologies, let me rephrase it: ... an underperfused state.
A shocked state doesn't necessarily mean that physiological regulation has been lost, in fact it is a result of physiological regulation that leads us into a state of shock. It is bodies way of maintaining vital perfusion as best as possible. By realizing that the vital organs are hypo-oxygenated and/or hypo-perfused, the body shunts blood towards the vital organs by means of peripheral vasoconstriction.
By virtue of the fact they freedivers can function in a hypo-oxygenated and hyper-capnic state means that there is some physiological derangement, however we just train our bodies to sustain that derangement for a certain period of time, after which the state returns to within normal physiological limits.

 

[sebastien murat]

Rights your are. Its interesting to note that in some animals these states are the 'normal' situation, e.g., hibernation for 8-9 months, diving 80-90% of the time. What I'm getting at with all this is, not to get locked down into conceptual/semantic constructs that limit one's a ability to see things clearly.

 

[Grubby]

Allow me to reattempt what I said in my previous post as I feel that I was not very good at communicating accurately what I was thinking.

The best definition of SHOCK is "an inadequate delivery of oxygen (and other vital substrates) to respiring cells" (and of course, the inadequate removal of the waste products of metabolism - hence importance of CO2 monitoring)

With the above definition in mind could it not be possible that divers do end up in a state of shock? Fair enough it's not from a traumatic injury that results in blood loss, or from a spinal injury or etc. Understandably the vital circulation is still intact however the circulation to non-vital organs is compromised.

As for the state being fully regulated, regulated yes, fully there might be a few individuals who can claim to be in full control of their MDR, however the majority of us can't. Yes, there are ways to turn it on a little quicker, but can we turn it off as quickly and at our whim whilst still diving to considerable depths? To a certain degree there is a retardation of physiological actions; despite our bodies wanting to breathe we have trained our bodies to go that little bit longer. Many of our actions result in pathological conditions that we continue to dive with and in some cases accept as indicators and signs of various stages of the breath hold.

There could be various causes of shock: hypovolaemia, sepsis, anaphylactic, neurogenic, cardiogenic and even increased intra-thoracic pressures could cause obstructive shock. I agree that the word "shock" does sound as if we are on the edge of death, however with the above definition in mind it's not such a stretch of the imagination.

Ladies and gentleman, I may be incorrect in my train of thought and open to correction. I might be clutching at straws, but I think it is a case of "a rose by any other name".

Sebastien, I do apologise if I irked you a bit with that comment, was not my intention.

 

[Grubby]

Thanks Sir, you are correct. One of my worst traits is my stubbornness and the ability to not let go of something.
Great discussion thanks for your input.

 

[sebastien murat]

Not at all irritated..your know how text doesn't capture nuances.
Clearly your are right in many ways. Ultimately, the hypoxic state must develop sufficiently slowly enough to mount defenses. And, indeed, a reversal of the DR during ascent (are greater than FRC) could be considered maladaptive if cannot conserve sufficient O2 to avert a BO. Moreover, chronic hypoxia is known to result in pathology.

 

[sebastien murat]

PS: peripheral vasoconstriction results in rapid cooling of non vital organs/tissues, thereby lowering their O2 consumption; the generally cold surrounding water accelerates the cooling process. Note: this is not a hypometabolic state but a normal condition, metabolism is at a new set-point.

 

[Grubby]

Indeed Sir, 100% correct. Inline with your research. Please could you get hold of some info for me at your convenience, it'll make some great bedtime reading.
Always keen to try understand a new concept everyday.
Thanks once again.

 

[Ronnie]

Allow me to reattempt what I said in my previous post as I feel that I was not very good at communicating accurately what I was thinking.

The best definition of SHOCK is "an inadequate delivery of oxygen (and other vital substrates) to respiring cells" (and of course, the inadequate removal of the waste products of metabolism - hence importance of CO2 monitoring)

With the above definition in mind could it not be possible that divers do end up in a state of shock? Fair enough it's not from a traumatic injury that results in blood loss, or from a spinal injury or etc. Understandably the vital circulation is still intact however the circulation to non-vital organs is compromised.

As for the state being fully regulated, regulated yes, fully there might be a few individuals who can claim to be in full control of their MDR, however the majority of us can't. Yes, there are ways to turn it on a little quicker, but can we turn it off as quickly and at our whim whilst still diving to considerable depths? To a certain degree there is a retardation of physiological actions; despite our bodies wanting to breathe we have trained our bodies to go that little bit longer. Many of our actions result in pathological conditions that we continue to dive with and in some cases accept as indicators and signs of various stages of the breath hold.

There could be various causes of shock: hypovolaemia, sepsis, anaphylactic, neurogenic, cardiogenic and even increased intra-thoracic pressures could cause obstructive shock. I agree that the word "shock" does sound as if we are on the edge of death, however with the above definition in mind it's not such a stretch of the imagination.

Ladies and gentleman, I may be incorrect in my train of thought and open to correction. I might be clutching at straws, but I think it is a case of "a rose by any other name".

Sebastien, I do apologise if I irked you a bit with that comment, was not my intention.

Yes, shock has been defined as respiratory failure at the cellular level. To be honest, I've never found that definition as particularly helpful. I have a quip when teaching, shock is what kills you - and given the cellular definition that's actually true.

Clinically, the term is rarely used in this way. Respiratory failure and its sequelae might be shock in a theoretical context, but when clinicians are trying to save the life of someone in respiratory arrest, they would find it unhelpful if someone started telling them that their patient was shocked.

Multicellular shock is more useful concept in the real world.

 

[Grubby]

Yes, shock has been defined as respiratory failure at the cellular level. To be honest, I've never found that definition as particularly helpful. I have a quip when teaching, shock is what kills you - and given the cellular definition that's actually true.

Clinically, the term is rarely used in this way. Respiratory failure and its sequelae might be shock in a theoretical context, but when clinicians are trying to save the life of someone in respiratory arrest, they would find it unhelpful if someone started telling them that their patient was shocked.

Multicellular shock is more useful concept in the real world.

Ronnie, you're 100% correct. Theoretical definitions are there to form a basis of understanding, practical application of that knowledge is totally different as I'm sure you will agree.
I have agree with Sebastien when he says it's a case of semantics, and I'll admit that I was the party being particularly focused on semantics.
All in all I feel that the physiology and the adaptations to the derangements that free divers develop is a really interesting topic, at least from a clinical point of view. These adaptations would also alter the emergency care of a free diver a little and I'd like to find out how and why so that I can get a better understanding for myself as both a paramedic and as a novice free diver.