Equipment IPE and Regulator Adjustments

[SubSoul]

This was a year ago though, correct? Before the incident of pulmonary edema?

You mentioned in your first post that you were cleared to dive by two different physicians after the event. What did the providers who cleared you think caused the pulmonary edema?

Best regards,
DDM

They could not say if it was IPE or if I aspirated water. I vividly recall taking in a small amount of water through my mouthpiece so my assumption was aspiration. But they were the ones to introduce the possibility of IPE too. I believe that the report stated something along the lines of the pathology possibly being related to negative pulmonary pressure or aspirating a small amount of water while attempting to breath against a closed glotis under water.

Neither seemed apprehensive about me returning to dive other than advising me to start off with shallow dives and to avoid cold water. But I have chosen not to dive because the possibility of it being IPE is concerning to me.

My regulator was looked at and is working as it should. The only concern was that I had accidentally left the Venturi set to negative and the cracking pressure high. I guess I’m just trying to gauge my risk of a repeated incident if I return to diving. If the settings on my regulator could have possibly attributed to IPE?

 

[SubSoul]

Isn't a regulator supposed to work perfectly fine at all depths at any setting of those little knobs and switches?

That is my experience with my regulators anyway. I adjust the knob and open/close the switch for my own "comfort", but I've gone entire dives with them both "closed" and never had a problem.

That was my understanding although I always turn the Venturi to + and adjust the cracking pressure to were it feels best for me. It was brought to my attention after the accident that the -/high settings could have caused the breathing difficulties.

 

[grf88]

Another factor which I have not seen mentioned is overhydration that can increase the risk of IPE.

 

[lexvil]

Isn't a regulator supposed to work perfectly fine at all depths at any setting of those little knobs and switches?

That is my experience with my regulators anyway. I adjust the knob and open/close the switch for my own "comfort", but I've gone entire dives with them both "closed" and never had a problem.

No, if you can’t tell the difference the second stage needs tuning.

 

[jale]

Hi
You were unconscious at the bottom and your buddies took you to the surface. May be something happened during this phase.

 

[SubSoul]

Hi
You were unconscious at the bottom and your buddies took you to the surface. May be something happened during this phase.

Yes. What I remember is taking in a little water and the choking. But I felt like I couldn’t get any air in or cough anything out. Thankfully we were diving in a close group so I signaled for help and then went unconscious. The ascent was faster than ideal but still took 3 minutes so we didn’t “shoot” to the surface.

 

[grf88]

For those following this thread and who haven't seen SubSoul's edit then go to post 1 and read it as in adds a lot of additional information that may or may not be perntinent.

 

[BoltSnap]

Isn't a regulator supposed to work perfectly fine at all depths at any setting of those little knobs and switches?

No, re-read the posts above.

 

[CG43]

Hello

The European standard EN 250 specifies under 6.6 Regulators
A regulator with built-in adjustable sensitivity controls must be tested with minimum and maximum settings.
This means that in a complete breathing cycle, the work allways must not exceed 3 joules/L.
Settings: 62.5 L/min. (25 sinus strokes 2.5 L) at 6 bar .
That's a power of only 1,25W . It is hard to imagine that this low power can be a problem.

Additionally under 5.8 regulator
The breathing pressure peaks during inhalation and exhalation must be within + - 25mbar (25 cm water column).
If we add 25 cm possible difference between 2.stage and center lung , we have 50 cm water colum .
This is only a short-term peak, but it may not be really healthy anymore.

 

[Duke Dive Medicine]

Yes. What I remember is taking in a little water and the choking. But I felt like I couldn’t get any air in or cough anything out. Thankfully we were diving in a close group so I signaled for help and then went unconscious. The ascent was faster than ideal but still took 3 minutes so we didn’t “shoot” to the surface.

This is sounding more like the laryngospasm that @rsingler mentioned up-thread. It can happen post-extubation following surgery as he suggested, and it can also happen with water aspiration. In either case it can lead to negative pressure pulmonary edema (NPPE), so that alone could explain this event. I am not familiar with MTX regulators so can't speak to whether it's possible to dial one in far enough for inspiratory effort to have been a factor.

If immersion pulmonary edema was the precipitating event, you would have been able to move air but you would have felt short of breath. This too can lead to unconsciousness, but that isn't what you've described. I don't think it can be completely ruled out, but it seems less likely given all the information you've provided here.

I am a bit concerned about your mention of elevated troponin and demand ischemia, but if the physicians who examined you in person are confident of your cardiac health then I'd defer to them.

Just so it's not lost, your buddies deserve a lot of credit for making a safe and controlled rescue especially in the setting of laryngospasm, which can result in air trapping. The fact that you're able to tell your story here is a testament to their skill and level-headeness under extreme pressure.

Best regards,
DDM