Monoplace seizure

[miketsp]

Most mono's pressureize with o2. multi usually pressurize with air and use masks to devever o2

All the specs I checked give you the option and since O2 is more expensive than compressed air, mask usage is more economical.
This is an extract from one manufacturers site:

Mono (one), place (space); means a space for one. This particular one person chamber has many advantages. You will find installation and transport of this chamber easier. Because you do not want to tear down walls or doorways we made a space-saving 34" flange size using quick clamps for a shorter width so this chamber rolls through a 3' size opening. Our design requires less volume of gas to pressurize yet feels bigger as a low-profile gurney gives you more free space inside the chamber. Our stainless steel gurney makes patient transfer easy. This monoplace chamber can use oxygen or air for the increased atmospheric pressure. This chamber has two quick couplings for your oxygen or air supply. This allows patients to lay inside and breathe oxygen with or without a mask. If you want the chamber pressurized with air the patient will wear a mask or a hood for their oxygen; just connect your (70 psi or less) medical air source to the main flowmeter quick coupling. Connect your (70 psi or less) medical oxygen to the mask flowmeter quick coupling. Connect the supplied universal coupling exhaust line and vent it outdoors 8' or more above the ground. The six quick clamps can secure the hatch in 30 seconds and you are ready to pressurize.


From
http://www.oxytank.com/mono.htm

(very slow site)

 

[rmediver2002]

:11: How long did it take to flush the O2 low enough to stop the seizure? I know it depends on the size of the chamber, pressure (well that's usually 60 ft max in monoplace isn't it) and venting flow rates, but how long it took in chambers you worked with? Any head injuries from convulsing?

Most of the time we use "portable" dixie double locks (220 CF) to vent a chamber this size takes less than 10 seconds. (a mono placed would take even less)

I have not seen an O2 seizure, and in fact only know a couple people that have (the convulsion was in a large military system, no head injuries to the patient, the only noticable effect was fatigue). All systems I have worked (I would hope all systems treating patients) have established emergency protocols, swithing the patient to air is the established protocol for any symptom of CNS O2 toxicity.

I have seen twitching before during both treatments and surface decompression, but that is the only symptom I have encountered.

 

[LubaScuba]

Hmmm, it seems that you believe it is possible to achieve the venting flow rate to be rather science-fictional. How can you decrease a pressurized chamber atmosphere O2 percentage from 100% to 21% in only 10 seconds? Just imagine that you only need to replace the whole chamber atmosphere in 10 seconds which is even less than the actual volume needed to flush it as you are exhausting a 'nitrox' not the pure O2. Some monoplace chambers have as tiny maximum venting flows as 8.5CF (actual) per minute. Are you still saying you worked in a chamber that can flush in 10 seconds? Any new comments?

 

[Table6A]

flop, flop, flipity, flop, flop.......

sorry, feeling a little cynical today.

They would start an immediate assent, 60 fpm. and flush the chamber with air if they have that capability.

You would NOT begin your ascent during a O2 seizure. During the tonic phase, the patient is probably holding his/her breath. Switch to AIR at the first indication of an O2 hit as the O2 is the cause of the problem. You would then wait for the clonic phase to begin decompression. Only decompress while you can verify pt respiration. When in doubt, hold chamber pressure unless the physician orders otherwise (which I have never seen).

Any other view points?

 

[Table6A]

Best call JMHO Mono place should not be using O2 or mix in my opinion. BUT......I have never worked a Mono tube. Protocol would not allow 100%O2 @ >60fsw so....and it takes only seconds to flush a chamber.

Monoplace chambers are designed for 100% O2 (The ability to switch to AIR is usually an added feature). Also, most monoplace chambers are rated to 3 ATA (66 fsw).

L8R G8R

 

[Table6A]

Most mono's pressureize with o2. multi usually pressurize with air and use masks to devever o2

Correct. A gold star for babar!

 

[LubaScuba]

Switch to air??? You mean ask the unconscious patient to put air bibs on??? Or maybe to vent the chamber which would last a bit too long as previously mentioned. Clonic phase ascent? How fast would you go, as i can tell you that clonic phase breathing is far from how you want someone to breathe on ascent from 60ft. What about physical injuries from someone convulsing in such confinement? What i really wanted to question is the usage of the monoplace chambers at almost 3ATA oxygen which is normally the case in diving medicine. Lot of people who advocate monoplace chambers for treating DCI must have ignored the crucial difference between moderate O2 levels in non-DCI HBO treatments (where monoplaces just seem to work fine) and extremely high dosage of oxygen (!) needed to successfully treat DCI. Any thoughts?

 

[Snowbear]

:11: How long did it take to flush the O2 low enough to stop the seizure?

Seizures tend to be self-limiting, so it should not be necessary to remove the O2 to get it to stop. Besides that, breathing tends to stop for a short time during seizure. Also, the large amout of muscle action during a seizure tends to metabolize a lot of the O2 already in the person. Point is, there shouldn't be a huge rush to vent the O2 or to "ascend" the patient.

What's the big deal anyway?? It's my understanding that hyperoxic seizures are not that common in hyperbaric chambers and when they do occur, at least you know the patient isn't gonna drown. The probability of drowning when breathing resumes, not the seizure itself, is the primary reason hyperoxic seizures are such a serious concern for divers.

I thought the O2 concentration to the mask the patient breathes from could be adjusted to any percentage? Even if not, from others more knowledgable posters, it seems the O2 can be flushed from the chamber in 10 seconds if necessary.

 

[Table6A]

Switch to air??? You mean ask the unconscious patient to put air bibs on??? Or maybe to vent the chamber which would last a bit too long as previously mentioned. Clonic phase ascent? How fast would you go, as i can tell you that clonic phase breathing is far from how you want someone to breathe on ascent from 60ft. What about physical injuries from someone convulsing in such confinement? What i really wanted to question is the usage of the monoplace chambers at almost 3ATA oxygen which is normally the case in diving medicine. Lot of people who advocate monoplace chambers for treating DCI must have ignored the crucial difference between moderate O2 levels in non-DCI HBO treatments (where monoplaces just seem to work fine) and extremely high dosage of oxygen (!) needed to successfully treat DCI. Any thoughts?

My opinion:

1) The chamber operator (monoplace or multiplace) controls any and all breathing gases within the chamber. This includes AIR.

2) The chamber does not need to be brought to 20.9% O2 (AIR), though that is preferred. The seizure may subside at 60% O2 or 40% O2.

3) I prefer that a patient be brought to surface breathing normally, however, in the clinical setting, this is not a given.

4) Patients rarely have just one problem...people are more complex than that.

5) To ascend during the clonic phase, you only travel (slowly) a foot or two at a time while you are observing respirations. No respiration / no travel. (again...my opinion)

6) I always advise injured divers to seek a multiplace facility if available, however, there are times when monoplace is all you have...and yes, you can safely treat a DCI in the monoplace. It just wouldn't be my first choice.

7) Confinement is relative. My monoplaces are often confused for multiplace chambers. Not everyone has a tiny chamber. (Insert joke here ) My patients are in no more physical danger from convulsion in my chamber than anywhere else.

I hope that covered everything. I would not treat a DCI in a monoplace if a multiplace unit was available, but please remember time is a crucial factor. That said, I have treated DCI in the monoplace without difficulty.

Was this helpful at all?

~ Kip

 

[Table6A]

All the specs I checked give you the option and since O2 is more expensive than compressed air, mask usage is more economical.

We use liquid O2.

~ Kip