Oxygen Administration Skills- Did I miss something (like demand valves comin' back?)

[lamont]

I would like to say that I hope no one on here gets the impression that I am arrogant, egotistical or anything like that.

Yeah, comments like this don't make me think that at all:

If you want to argue pulmonary physiology and oxygen administration techniques, you picked the wrong person to do it with.

 

[Fly N Dive]

I am against both of them as I feel that the first one is simply too expensive for what it does (compared to what other options are available) and potentially wasteful of oxygen and the latter is dangerous because of the risk of barotrauma

why would a DEMAND valve be more wasteful???? as opposed to a constant flow???

i agree that the the positive presure units are very dangerous in the hands of anyone not properly trained to use it, part of the reason it isnt taught in the dan O2 course.

 

[Skip Parker]

why would a DEMAND valve be more wasteful???? as opposed to a constant flow???

Now, now. Don't let logic get in the way of a good DAN bashing!

 

[medic_diver45]

Yeah, comments like this don't make me think that at all:

I wouldn't pick an argument with a divemaster or tech diver about decompression cause he probably knows more about it than I do. I didn't mean that in a "don't f--- with me sort of" sense more of a "I deal with giving oxygen for a living, so I probably know it better than you do and I'm trying to teach you about it".

 

[medic_diver45]

why would a DEMAND valve be more wasteful???? as opposed to a constant flow???

i agree that the the positive presure units are very dangerous in the hands of anyone not properly trained to use it, part of the reason it isnt taught in the dan O2 course.

There MAY be situations where the demand valve wastes less O2 (calm patient who breathing nice and slow- which in real life happens very infrequently) than an NRB, but if your patient is breathing fast (which happens all the time) and the flow limit is 40 L per minute, your precious little O2 bottle is gonna last about 5 minutes. If you're patient is calm as us sitting here it MAY last 15 minutes with the demand valve (seeing as an average person, depending on size and metabolic rate at rest moves about 6-10 liters of air per minute when PERFECTLY HEALTHY AND NOT IN DISTRESS).

Now you can do the exact same thing, give the same concentration of oxygen with a non-rebreather and no matter how fast the patient breathes, you're only burning 15 l/min. Which buys you anywhere from 12 minutes for a C tank to 25 for a D tank. I'm just trying to get you to look at this from a logical standpoint hear. I know it's hard to look at something from a different viewpoint when you've been taught that only one way is correct....in emergency medicine there are few cases where there is only one "right" way to do something- there are often better, more effective, simpler or cheaper ways to do things, as is the case here.

This has less to do with DAN bashing- as I said I think they do a great job when it comes to specialized treatment guidelines and providing assistance when necessary, however when they are recommending a piece of equipment simply because of it's cost (ability to make a profit for them)- that's not acceptable in my book and I am trying to point it out.)


Wait, but the demand (Elder) valve is taught in the "advanced" O2 course isn't it? I've had like five people on this board tell me that it is taught in that course for ventilating persons who have stopped breathing. Can someone clarify this for me? But as far as the barotrauma thing is concerned, I've stated my case as best I can and I hope you will look at it and take it for what it is, a statement by a medical professional who deals with ventilation on a daily basis and walk away better educated and more cautious than you were before.

 

[BigJetDriver]

But as far as the barotrauma thing is concerned, I've stated my case as best I can and I hope you will look at it and take it for what it is, a statement by a medical professional who deals with ventilation on a daily basis and walk away better educated and more cautious than you were before.

Stephen,

I respect your background and training. I generally defer to folks who do the job at hand on a daily basis.

I will simply point out that, in training as a DMT at UTMB Galveston, we were taught the use of the MTV-100 (manually triggered resuscitaion valve) and several other similar types. All of the new ones that I know of have circuits limiting both the pressure and volume of their output. They are not without their contra-indications and limitations, but nothing in the realm of medicine is "risk free", is it? They are, however, acceptable for use here.

Cheers!

 

[medic_diver45]

Stephen,

They are, however, acceptable for use here.

They may be acceptable, but the point I was trying to make (after I got away from the barotrauma issue) was that there are simply safer, more cost effective ways of doing the same thing. That's all. The only contraindications for a non breather mask that I am aware of are:
-Lack of sufficient oxygen flow to vent carbon dioxide from the mask (but this happens with any sort of high-flow oxygen system)
-Persistent vomiting (but this is a relative contraindication to using the mask (and this rule would apply to demand valve too)- if the patient pukes, pull the mask off- Simple enough eh?

The other problems with a demand valve can include increased work of breathing (basically how hard you have to suck to pull in air). Now for a healthy person this shouldn't pose a problem, but for a critically ill patient with the deck already stacked against them (someone who has dropped a lung for instance) creating a negative pressure necessary (I'm assuming that they device is pressure triggered and not flow triggered) can be battle. Basically they have to work so hard to get O2, that they build up (or worsen) an oxygen deficit. In any case, patients can look like they are moving a lot of air (because of the visible signs of them working to breath) but be actually getting little or no air. This is what you see in patients with severe asthma attacks and collapsed lungs (pneumothoraces (sing. pneumothorax)). These patients would be hard pressed to be able to pull a breath from a demand valve (have someone sit on your chest while you try to breath through your regulator- not easy huh? Same basic idea.....the work of breathing is so great that the body can not make it work through the task at hand). This presentation of the apparent work of breathing can be confusing to medical professionals who are unfamiliar with it due to infrequent exposure to such patients (i.e. most nurses (those who don't work in critical care), family practice doctors, etc) so I would not expect (and can not demand) better from laypersons.

That's why my stance is what it is- that demand valve simply is too expensive and has too many risks involved with it's use (as outlined above and in previous postings) to be considered the optimal delivery method for oxygen to a critically ill patient. JMHO.....

 

[Skip Parker]

There are two common kinds of emergency oxygen delivery equipment: demand and constant-flow. While both systems are capable of delivering high percentages of oxygen, only the demand valve used with a tight-fitting mask can deliver 100 percent inspired oxygen.

The demand regulator system has many other benefits for divers. It's similar to a scuba system, so training is simplified. It's also the only system that delivers 100 percent oxygen, which gives the greatest nitrogen washout benefit. The demand system conserves oxygen better than the constant-flow system, and because the demand regulator is activated by the diver's inhalation and stops delivering oxygen when the injured diver exhales, it meets 100 percent of an injured diver's inspiratory (breathing) needs. Although the constant-flow system is not as efficient as the demand system, because its ability to deliver high percentages of inspired oxygen varies, it is still a viable system if used properly.​

From the horses mouth....​

 

[rjchandler]

To put together a fully stocked O2 kit (a stripped down version of what I have in my personal vehicle) you would need:

Oxygen (minimum of a "D" cylinder, preferably a "Jumbo D" or "E" would be better") Source: Welding supply company (that's where most ambulance services get theirs from) Cost: $40-60 depending on location

Oxygen regulator- $90-100 (you can buy them from medical supply catalogs; here's where I got mine www.buyemp.com

CPR Barrier Mask w/ O2 inlet- $15 or a Bag-valve-mask device $15

Non-rebreather mask- about $2.50 (always a good idea to carry at least two of them


TOTAL COST: about $200.00 tops, and that's if you include a bag to put all of it in (the one's designed to carry O2 run about $25.00 and up)

No need to waste several hundred dollars on an expensive outdated piece of equipment. You get just as high, if not higher, 02 concentrations from a NRB as you do an demand valve and it is much more comfortable for the patient.

Nice site - thanx

 

[medic_diver45]

From what horse's mouth? That's probably from the DAN manual or something...Show me an actual peer-reviewed article from an unbiased source and then I might believe that. The only journal article I can find that says these things can give 100% O2 states "The results showed that an acceptable Fio2 could be reliably achieved only with the continuously ventilated hood system" and the last time I checked, DAN doesn't stock those in the little kit they sell. Yes, under careful laboratory settings they probably can give 100% O2, but in the field (without a tube down the patient's throat) that's a pipe dream.

No system (unless the patient is intubated) is without leaks, unless you really force the mask down on a patient's face and even then they're probably not going to tolerate that. You'll have the same problem with a demand valve that you would have with a NRB. It's been documented in study after study. Even patient who are given O2 through a CPAP system (normally used to treat sleep apnea) which consists of a mask with a head strap system to keep a tight seal seldom get anything above 95% oxygen concentration in clinical practice due to unavoidable leaks in the system. No imagine what kind of leaks you'll get when you have half a pound of metal attached to the mask. Most people who hold masks against their own face don't seal it very tightly, and most people who seal a mask against other people's faces push too hard and cause more leaks than would otherwise occur (the trick to solve thisis to pull the patient's face into the mask by grasping the edge of the mandible, not the other way around). But like I said, if the patient is even semi-conscious they probably won't let you do this and will fight you every step of the way.



What comes out of the tank maybe 100% pure O's, but it get's diluted by leaks in the system; Here are some points from medical references that support this:

Egan's Fundamentals of Respiratory Therapy- p. 750
"Because it is a closed system, a leak free nonrebreathing mask with competent valves and enough flow (that is >12 L/min) to prevent bag collapse during inspiration can deliver 100% source gas (in this case Oxygen)." But as I said up there, leaks happen.....both in demand valve systems and NRB's.....it's just a matter of how much you want to pay to have those leaks I guess....


And as for the work of breathing statement I made earlier, here's support for that:
According to an article in the May 1994 issue of Anesthesiology: ".....reflects the reduced oxygen cost of breathing when the.....continuous flow system was used during weaning." Basically, demand valves increase the oxygen demand and work of breathing.

I have come to the realization that I am not going to convince you to even look at things from the medical grounded side of things. I feel that there is no point in wasting my breath any further and that I need only state that you have been warned on the risks and downsides of these devices. While they make not be dangerous, they are simply not the best choice out there. I know of no other way to demonstrate that to you. If it were me, I'd want a non-rebreather and if I am treating the patient they will get a non-rebreather; As I've said before, there are many ways to do something in medicine, but some of them are just more effective.

We should all be looking out for what is in the patient's best interest, because some day we may be the patient. I think financial reasons have clouded the judgement of the agency upon which you are relying for your information. Relying on only one source of information can be a dangerous thing in medicine.

Thank you for a stimulating conversation that has required me to remain on my toes.