Pulmonary Oedema incident

[Duke Dive Medicine]

John,

Arterial blood pressure would not be a very accurate measure of fluid redistribution. Dr. Smith discussed some effective measures above and as far as I know, nobody has tried it. This may be some low-hanging fruit for an aspiring researcher.

Best,
DDM

 

[InTheDrink]

Hi,

Indeed and like I say, the human mechanics are probably beyond me so anything I say is with reservation and humility. And probably stupidity to boot.

I'm so tempted to say what I think but it's probably wrong, misleading and certainly without anything but anecdotal value. I'm just very keen to assist in whatever way I can, including past and current experience, to help make this issue better understood and more easily preventable.

I see mistakes frequently that make me shudder as I feel 'this is asking for it'. Although so far they don't get it.

John

 

[Duke Dive Medicine]

John,

You're anything but stupid. You've assisted immeasurably by posting in detail about your incident, being honest and forthcoming with answers to questions, providing periodic updates, and helping spark a fantastic discussion about the topic. This is one of the best threads on SB thanks in a large part to you.

 

[peterbj7]

Where/who with do you dive, John? I was a w/e regular there until I moved across the Pond.

 

[InTheDrink]

Where/who with do you dive, John? I was a w/e regular there until I moved across the Pond.

I dive all over really. See my profile. I get to travel a fair amount. Who do I dive with? My buddies mainly: Tony Evans and Rachel Oates. They're now MOD 2/3 CCR and doing 100m+ dives. SimonTW is their main guiding light as an instructor and buddy for the bigger dives. He's an awesome dude who I 100% owe my life to. My buddies are now doing fun things finding new wrecks etc. but I'm left spending my time with lobsters and sharks. Not that awful really

We're probably not that well known round the circuit although I imagine Tony will be in time (although his trim is ****) as he's a very solid diver with a very clear mind. He's dived with a few 'names' but I can't recall them off hand.

John

---------- Post added December 19th, 2012 at 09:36 PM ----------

John,

You're anything but stupid. You've assisted immeasurably by posting in detail about your incident, being honest and forthcoming with answers to questions, providing periodic updates, and helping spark a fantastic discussion about the topic. This is one of the best threads on SB thanks in a large part to you.

Well that's very kind. Let me know if and how I can contribute.

 

[TSandM]

Interesting point about edema at the end of airplane flights. I had a vague memory that I had learned something about elevated aldosterone levels at altitude, but upon doing some research, it turns out that's wrong . . . in fact, acute exposure to high altitude has a diuretic effect. So I suspect the lower extremity edema due to flying is simply hydrostatic (due to the fact that the legs are below the heart, and immobile).

However, this raises an interesting question about whether, if the diuretic hormones are increased with decreased pressure and ppO2, are they reduced by increased pressure and ppO2? If that were the case, it might have something to do with why some of the cases of IPE have been seen on the later dives in a series. (Increased hormone levels coupled with diligent hydration efforts between dives could lead to volume overload.)

 

[retendokid]

I think we have to be careful when comparing hemodynamic changes in anesthetized surgical patients to those in divers.

Pressure is equally distributed in the body. Once an individual is immersed, the ambient pressure at which the immersion occurs has little bearing on fluid redistribution, e.g. the immersion-related fluid redistribution at 2 ATA will be essentially the same as that at 6 ATA.

Can you elaborate on how ambient pressure is a factor in dependent edema while flying?

Best,
DDM

DDM, thanks for the clarification..you are absolutely correct---cardiovascular/hemodynamic changes in anesthetized patients are different from divers or any other awake person (typically blunted from volatile agents and other sedatives). But my main point was that I'm always amazed at the capacity of the human body to redirect/relocate fluid under various conditions, even changes in body position, and its something we see real time during surgery through invasive monitoring. But again, thanks for reigning me in, as this discussion is about divers not patients.

Peripheral edema while flying is mostly dependent fluid collection, and the lack of muscle activity which plays a key role in lower extremity circulation, but reductions in cabin pressure (to approx 8000 ft) can lead to mild hypoxia due to reduce partial pressures of oxygen, abdominal distension/bloating 2ndary to expanded intestinal gas, and possibly even increased venous pooling. Hypoxia is a mechanism thought to disrupt capillary permeability and lead to extravasation of fluid, increased intrabdominal pressure can reduce venous preload worsening dependent edema, and some fascinating studies looking at negative pressure on regional blood flow suggest venous pooling. Of these, sitting with your legs down is still likely the greatest contributor by far.

John-thank you for your original post, and your curiosity in wanting to discover an explanation for your near miss. Without your courage to share your episode, as well as facilitating subsequent dialogue, none of us would be any the wiser. Its through fertile discussions like those of this thread that we have hope of better understanding the challenges facing divers.

 

[InTheDrink]

So my, absolute, probably throw away list of what to look at as yourself a diver:

BP starting point...plus any one or more of your favorites....
Anxiety
Task loading
Work (e.g. current)
WOB (including ADV)
Meds (especally beta blockers but not exclusively)
Dehydration (all the normal reasons why this is bad)

Having a bad day before may also be of interest. Ppl should be aware of warning signs, like rattling, wheezing, unusual cold, etc.

Ultimately when I look and read about different people that have had this, and the information I've got isn't great, is that keeping anxiety and work load down will keep you safe. Just my feeling, not a doctor or scientist. I think CCCR has special risks also.

Ultimately I presume that total cardio load - so add all my factors above together - is what will make your pulmonary capililliaries leak or not. But what do I know? Very little. But I suspect if the factors I mention above are controlled then maybe, for some/most groups of divers the risk can be managed. Like I say, as a novice but at the front end.


John

 

[peterbj7]

John - I really meant what operators/boats you use.

Can you tell me what MOD 2/3 CCR means? What agency uses that designation?

 

[InTheDrink]

John - I really meant what operators/boats you use.

Can you tell me what MOD 2/3 CCR means? What agency uses that designation?

For the few boat dives from here I've been out on the Buccaneer and the BSAC club.

Mod 2/3 - my understanding, which may well be flawed was that mod2 was normoxic trimix and 3 was hypoxic with some agencies. With PSAI I think there's no mod 2/3 distinction, maybe there's not with any agency. I only did Mod 1 so not sure about any of the above TBH.

---------- Post added December 20th, 2012 at 05:41 PM ----------

Oh and prob should mention its all out of Brighton where I live.