# Nitronox. Why isn't it used anymore?



## bigbaldguy (Jul 4, 2012)

Does anyone have past or current experience using nitronox (A mix of nitrous oxide 50% and oxygen 50%) in an EMS system? From what I've seen online it seems like the perfect treatment for pain in the prehospital system. Low risk of side effects, very little risk of drug seekers calling 911 for it, also helps alleviate anxiety. I've also noticed that it seems to be less used by dentists lately as well. Is it still used in any EMS system?


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## CANDawg (Jul 4, 2012)

bigbaldguy said:


> Does anyone have past or current experience using nitronox (A mix of nitrous oxide 50% and oxygen 50%) in an EMS system? From what I've seen online it seems like the perfect treatment for pain in the prehospital system. Low risk of side effects, very little risk of drug seekers calling 911 for it, also helps alleviate anxiety. I've also noticed that it seems to be less used by dentists lately as well. Is it still used in any EMS system?



I know it's still in the protocols here for both general pain management and fractures/dislocations, but not sure on how widely it's used as opposed to Morphine/Fentanyl. Here it's a BLS drug though, so it might see some wider use.


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## Aidey (Jul 4, 2012)

I loved having it. It takes effect within a couple of breaths, so it was great to pop someone on that while working on getting the IV and giving them morphine. Also good for people allergic to morphine (all we carried) or who didn't like opiates and/or wanted to control how much medication they got. I'm not sure if that agency is still using it or not. 

As for why it isn't very common, the reason I hear is because it is almost impossible to account for. There isn't a very good way to track it and make sure no one is abusing it.


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## bigbaldguy (Jul 4, 2012)

I see a few places on google that have protocols written for it but nothing about it actually being in use anywhere. It's like mast trousers in Texas we have to know how to use them but nobody even carries them anymore, but unlike mast trousers I can't find anything on why it's not used.


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## the_negro_puppy (Jul 4, 2012)

We used to have it known as "entonox" now we just have methoxyflurane as a substitute.


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## jwk (Jul 4, 2012)

Maybe it has something to do with the health risks of long-term exposure to health care workers.  We scavenge waste anesthetic gases in the OR, and have frequent spot-checks to measure N2O concentration in the OR.  Unless you're using a closed system, there really is no way to scavenge the waste/exhaled gases.

MOF (methoxyflurane) is used almost exclusively in Australia and New Zealand as a method of self-administered pain control.  It's an anesthetic gas with a high incidence of renal toxicity.  It's use has been totally abandoned in the US - I don't think it's even commercially available here anymore.


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## Shishkabob (Jul 4, 2012)

I had it at my internship department, used it on many patients and loved it. 

However, due to the FDA, the Oxygen and Nitrogen must be bottled separately and thus cost much more.


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## bigbaldguy (Jul 4, 2012)

Linuss said:


> I had it at my internship department, used it on many patients and loved it.
> 
> However, due to the FDA, the Oxygen and Nitrogen must be bottled separately and thus cost much more.



Ahhh and there you have I bet. Cost issue?


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## bigbaldguy (Jul 4, 2012)

jwk said:


> Maybe it has something to do with the health risks of long-term exposure to health care workers.  We scavenge waste anesthetic gases in the OR, and have frequent spot-checks to measure N2O concentration in the OR.  Unless you're using a closed system, there really is no way to scavenge the waste/exhaled gases.
> 
> MOF (methoxyflurane) is used almost exclusively in Australia and New Zealand as a method of self-administered pain control.  It's an anesthetic gas with a high incidence of renal toxicity.  It's use has been totally abandoned in the US - I don't think it's even commercially available here anymore.



Good info. Thanks.


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## JakeEMTP (Jul 4, 2012)

Startup and maintenance costs high.

Bulky to store and may not be as easily carried to a rescue scene as morphine or fentanyl.

Risks to personnel unless a scavenger system used and ambulance is well vented. (already mentioned)

Patient must be able to self administer.

Long list of conditions (pneumothorax, COPD hx, chest trauma, head injuries, facial injuries, bowel obstruction, CHF) where it should NOT be used.


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## usalsfyre (Jul 5, 2012)

The number one reason is there's not a commercially available EMS friendly blender made anymore....


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## abckidsmom (Jul 5, 2012)

usalsfyre said:


> The number one reason is there's not a commercially available EMS friendly blender made anymore....



That department you used to work at is still using those antique blenders. When they get banged or dropped, everybody has a seizure cause they can't be replaced.


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## usalsfyre (Jul 5, 2012)

abckidsmom said:


> That department you used to work at is still using those antique blenders. When they get banged or dropped, everybody has a seizure cause they can't be replaced.



Those things were old when I worked there in 2004....


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## Tigger (Jul 5, 2012)

When I rode with St. John in Auckland (New Zealand) a coupe of weeks ago we gave one patient etonox. Patient was a 17 yo female who had sprained/possibly broken her ankle at a skating rink, no other complaints. Given this, the patient being hysterical, and the seven minute transport, the crew opted not to start and IV and use etenox along with PO liquid acetaminophen. In five minutes time 9/10 was reduced to 5/10 and patient was noticeably less anxious. I was fairly sold on it, it was in it's own D-tank sized cylinder that we just threw on the stretcher like you would oxygen when you get on scene. It had a mount right at the stretcher head so the patient could continue to use it during transport.

I was unaware of the potential for harm to providers however, obviously they do not see this as an issue down there. As with any drug, there are going to be contraindications so I don't see why that should stop its use.

A common theme on this board has been that the US EMS perspective on pain control is one of "all or nothing," and not everyone needs opiate based pain management. Perhaps entonox, with the proper delivery mechanism, could help fill this gap. It's a BLS drug in NZ too, the crew was shocked when I a) didn't know how to administer it and b) that we have ambulances in major urban areas that carry no more than pillows and cold packs for pain control.


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## the_negro_puppy (Jul 5, 2012)

jwk said:


> Maybe it has something to do with the health risks of long-term exposure to health care workers.  We scavenge waste anesthetic gases in the OR, and have frequent spot-checks to measure N2O concentration in the OR.  Unless you're using a closed system, there really is no way to scavenge the waste/exhaled gases.
> 
> MOF (methoxyflurane) is used almost exclusively in Australia and New Zealand as a method of self-administered pain control.  It's an anesthetic gas with a high incidence of renal toxicity.  It's use has been totally abandoned in the US - I don't think it's even commercially available here anymore.



The renal and hepatic toxicity from methoxyflurane was only found at high doses required for anaesthesia. The low dose levels given as inhaled analgesia have been found to be safe provided you are not using the drug regularly.


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## jwk (Jul 5, 2012)

the_negro_puppy said:


> The renal and hepatic toxicity from methoxyflurane was only found at high doses required for anaesthesia. The low dose levels given as inhaled analgesia have been found to be safe provided you are not using the drug regularly.



But in a litigious society like the US, that concern is more than enough to take it off the market.  Even 30 years ago, it's use had become very limited here, and I probably haven't seen it in 25 years.


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## mycrofft (Jul 5, 2012)

Nice article in Wikipedia:
http://en.wikipedia.org/wiki/Nitrous_oxide_and_oxygen

Federal OSHA standards:
http://www.osha.gov/SLTC/healthguidelines/nitrousoxide/recognition.html


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## Flight-LP (Jul 5, 2012)

bigbaldguy said:


> I see a few places on google that have protocols written for it but nothing about it actually being in use anywhere. It's like mast trousers in Texas we have to know how to use them but nobody even carries them anymore, but unlike mast trousers I can't find anything on why it's not used.



So I take it CCEMS no longer carries it? I loved the stuff! Simple and effective with minimal side effects.


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## bigbaldguy (Jul 5, 2012)

Flight-LP said:


> So I take it CCEMS no longer carries it? I loved the stuff! Simple and effective with minimal side effects.



Nope, haven't even heard of it mentioned. I'll have to ask next time I run across one of the old timers  Maybe I'll run into one while I'm taking the medic course.


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## 46Young (Jul 5, 2012)

IN Fentanyl is available. Entonox is not needed anymore.


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## Tigger (Jul 5, 2012)

46Young said:


> IN Fentanyl is available. Entonox is not needed anymore.



What about for the non-paramedics amongst us?


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## EpiEMS (Jul 5, 2012)

Tigger said:


> What about for the non-paramedics amongst us?



Agreed. For AEMTs, say - why not give them something analgesic other than the ice, splinting, and padding that we EMTs have?


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## Handsome Robb (Jul 5, 2012)

46Young said:


> IN Fentanyl is available. Entonox is not needed anymore.



I personally don't like IN fent. It has never worked whenever I've used it. 

Nitronox is awesome. We still have it for standbys with ILS staffing, not on the 911 units anymore though which is a shame. 

Our ALS ski patrollers carry it and use it pretty frequently and I always ask to use it to get the patient out of their ski jackets and what not so I can get an IV going. Works like a charm.


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## the_negro_puppy (Jul 5, 2012)

NVRob said:


> I personally don't like IN fent. It has never worked whenever I've used it.
> 
> Nitronox is awesome. We still have it for standbys with ILS staffing, not on the 911 units anymore though which is a shame.
> 
> Our ALS ski patrollers carry it and use it pretty frequently and I always ask to use it to get the patient out of their ski jackets and what not so I can get an IV going. Works like a charm.



Exactly. At the moment we can only give I.N fent to children. Our alternative (methoxyflurane) takes less than 5 seconds to prepare and works well if used properly, particularly with younger children who fear needles. Its great for stuff like fractured femur, get a quick hx give immediate inhaled analgesia while you obtain IV access and give Morphine. I can then be used in conjunction with morphine. I have had one patient with a fractured femur state he could not even feel his leg at all after 2 x 5mg  IV morphine + methoxy while we were applying a traction splint to his leg.


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## bigbaldguy (Jul 5, 2012)

Do gases like nitrous or methoxy have a synergetic effect on IV meds? If you give gas can you use less fent or morphine?


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## the_negro_puppy (Jul 6, 2012)

bigbaldguy said:


> Do gases like nitrous or methoxy have a synergetic effect on IV meds? If you give gas can you use less fent or morphine?



Yes it appears very much so. I am always cautious when using multiple types of analgesia. If you aggressively inhale penthrane in can virtually render you unconscious, bradycardic. People have to be watched when hey self administer it. At the start they dislike the taste but as soon as they get used to it they puff away more and more


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## MikeCivitello (Jul 6, 2012)

bigbaldguy said:


> Does anyone have past or current experience using nitronox (A mix of nitrous oxide 50% and oxygen 50%) in an EMS system? From what I've seen online it seems like the perfect treatment for pain in the prehospital system. Low risk of side effects, very little risk of drug seekers calling 911 for it, also helps alleviate anxiety. I've also noticed that it seems to be less used by dentists lately as well. Is it still used in any EMS system?



The main reason why you don't hear much about Nitronox is because the Nitronox device went out of production about 5 years ago - and there has been no one to service existing units.  The Nitronox device was owned by Matrx Medical - which gradually sold off various devices and business units over the years - including Nitronox.  Nitronox got bought and sold a few times over a few year period and eventually ended up with a company that was not interested in manufacturing or servicing the device.

As of last month this has changed.  Porter Instrument (Hatfield, PA) has aqcuired the rights to the Nitronox device and will begin manufacturing them again in the near future.  Disclaimer - I work for Porter.  I want to make sure I adhear to the forum rules - so not sure what I can/can't say beyond that.

I read through all of the posts and wanted to respond to some of the comments.  Hopefully this information is helpful.

Nitronox vs Entonox - Nitronox is a "device" (not a gas) that blends both 02 and N20 (from separate cylinders) at a 50% mixture "on-demand" through a demand valve.  Entonox is a "pre-mixed" gas of 50/50 02 and N20.  Enotonox is not FDA approved for use in the US. 

Nitrous Oxide use is absolutely widely used in Dental Offices.  Approximately 50% of all US dental offices use N20 to help with anxiety as well as offer Minimal Sedation.  About 95% of all Pediatric Dentists and Oral Surgeons use N20.  No dental offices in the US use Nitronox or similar system.  They use different types of systems that are continuous flow (not demand flow) and not patient self administered - but administered through a nasal hood breathing circuit that is on the patients nose at all times.  Basically the dentist controls both the flow rates and can adjust the percentage mixture from 0-70% N20.  Nitronox devices are demand flow, patient self administered (with full face mask or mouth piece), and fixed at 50%.

Occupational Exposure Issues - this is definitely an important issue and should never be ignored.  Here in the US NIOSH has suggested 25 ppm over an 8 hour time weighted average for safe exposure rates.  In other countries this is as high as 100 ppm and some countries do not monitor or suggest exposure safety rates at all.  When using any mixture of N20 in a closed space (dental office, OR, office setting, etc.) you absolutely have to be connected to a Vacuum or WAGD system/wall outlet for safe and effective scavenging of waste gas - and to vent the gas to the outside.  First Responders using something like Nitronox should have minimal exposure issues if using outside or if in an ambulance - as long as the ambulance is vented properly (open windows, vent system, fan, etc).  Also - keep in mind the length of time for exposure for a First Responder would be substantially lower than that compared to use in Dental or Hospital.  Dental and Hospital facilities are using a different type of N20 sedation device (continuous flow - not demand flow - which means more gas is flowing) - as well as for longer procedures - typically 30-60 minutes in length.  First Responders may be exposed for a 15 minute duration - with only periodic use as the patient is self administering with a demand valve system.  Maybe some of the people still using could chime in with experience on this and how they handle use inside the ambulance?  

Cost - "pre-mixed" gas will typically cost more than using a device to "blend/mix" the gas - so I wouldn't say this is a reason why use dropped off.  It had to do more with not having a device and somewhere to get devices serviced.  We have reps in Europe where Entonox and Kalinox are used widely - and that was at least what they informed us.  Obviously there is an up front cost of purchasing a device - but if properly cared for - they should last a long time.

Again - hope the information is helpful.

Mike Civitello


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## Tigger (Jul 6, 2012)

When I rode in NZ we didn't even open a window in the ambulance. It was a demand valve type system, I can't imagine that much gas actually "escaped" into the vial ambulance, especially given The short transport.


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## mycrofft (Jul 6, 2012)

Very few use nitrous in offices around here (Central California/Sacramento area).


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## medicasaurus (Jul 7, 2012)

We use Entonox regularly here in B.C. and it's even on the EMR list of medications (105hr course). We carry a pre-mixed D sized tank with a on-demand regulator and the ambulance has vents which must be active when administering the gas. Works well for most cases however there is a push at the Primary Care Paramedic level to have a injectable medication as another option.


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## Craig Alan Evans (Jul 7, 2012)

usalsfyre said:


> The number one reason is there's not a commercially available EMS friendly blender made anymore....



We have been using it for the past 20 years and this is definitely the no 1 reason you don't see it much. We are still using our original devices. We can't find parts for them anymore. We can't find anything else on the market that is feasible. Accountability is easy as we weigh the bottles each day. No gas is ever leaked into the patient compartment as it is self-administered through a demand valve so gas is only flowing when the patient is inhaling.  There is definitely a patient population this drug is very useful for, but since IN fentanyl I have used it much less. Also in my experience I have found it either works really well or not at all.


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## jwk (Jul 7, 2012)

Tigger said:


> When I rode in NZ we didn't even open a window in the ambulance. It was a demand valve type system, I can't imagine that much gas actually "escaped" into the vial ambulance, especially given The short transport.



Breathe in, breathe out - where do you think the "out" gas goes?


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## Tigger (Jul 7, 2012)

jwk said:


> Breathe in, breathe out - where do you think the "out" gas goes?



I got the idea that such exhalations contained a minimal amount of gas when compared to the volume of the ambulance. New Zealand's worker protection laws are far stronger than our own, if this was a significant problem I have hard time believing it would be ignored.


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## bigbaldguy (Jul 7, 2012)

As I understand it the newer EMS version of this device will have a scavenger circuit that will remove exhaled or leaked gas.

From the website

• Built In Scavenging Interface - The Nitronox unit comes complete with a gas collection ring, tubing and a patented scavenging interface for the safe, effective removal of exhaled nitrous oxide.

http://www.porterinstrument.com/product/dental/Nitronox Portable Kit


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## MikeCivitello (Jul 9, 2012)

jwk said:


> Breathe in, breathe out - where do you think the "out" gas goes?



JWK is correct.  N20 is not metabolized by the patient - so pretty much whatever they inhale - comes back out when they exhale.  

The key with the first responder device is room air exchange and venting when used inside the ambulance.  If you were in a closed room this would be an issue.  The actual use would only be for a short period of time - and with proper venting exposure should be minimal.  Keep in mind it is an 8 hr time weighted average that NIOSH is looking at.

N20 used in dental offices and hospitals will always have a scavenging line connected to a wall vacuum outlet or suction system - as they are exposed to higher concentrations of N20 as well as for longer durations of time.  They also don't have the ability to open a window or turn on a vent fan.


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## jwk (Jul 9, 2012)

Tigger said:


> I got the idea that such exhalations contained a minimal amount of gas when compared to the volume of the ambulance. New Zealand's worker protection laws are far stronger than our own, if this was a significant problem I have hard time believing it would be ignored.



And they still use methoxyflurane in Australia and New Zealand despite the significant dangers associated with it.


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## Tigger (Jul 9, 2012)

jwk said:


> And they still use methoxyflurane in Australia and New Zealand despite the significant dangers associated with it.



I was told that St. John New Zealand no longer carries it methoxyflurane and instead uses exclusively etenox.


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## MikeCivitello (Apr 17, 2013)

Just as a follow up to posts in this thread - the device is now available again in the U.S. - as of this week!


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## ThadeusJ (Apr 17, 2013)

Mike did a great summary of the current status of devices.  I have worked in hospitals where there is no scavenging and they use it in the ED when snapping shoulders back in place.  My understanding is that it is still used to a fair extent in the UK by pre-hospital services.


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## boerbull (Apr 18, 2013)

Here in the Netherlands almost every ambulance carries entonox, but not everybody uses it. We are only allowed to use it outside of the ambulance. Problem is that most medics here don’t believe it works because they have tried it and it doesn’t work. My experience is that it is great to use in combination with Fentanyl. It lowers the stress levels and allows the fentanyl to work better.
I’ll use it for kids. For adults I prefer to use a combination of midazolam and esketamine if I know that I’m going to hurt them. That will knock them out just long enough to prepare them for transport. After that I use fentanyl during transport.


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## frdude1000 (Apr 18, 2013)

We have learned about Nitronox in my AEMT class.  I think the main problem is practicality (two separate bottles) as well as exposure risk.  The back of an ambulance is not a well vented place...the medication is self administered and the pt. will drop the mask once they have had enough.


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## Handsome Robb (Apr 18, 2013)

frdude1000 said:


> We have learned about Nitronox in my AEMT class.  I think the main problem is practicality (two separate bottles) as well as exposure risk.  The back of an ambulance is not a well vented place...the medication is self administered and the pt. will drop the mask once they have had enough.



The issue is getting the mixers.

They really aren't bad to use, plug the pigtail into your onboard o2 and have them hold the mask, turn on the exhaust fan and you're fine.

It's a demand valve mask so when they drop it it doesn't continuously flow, only when you breathe and create a vacuum in front of the mask, much like a SCBA/SCUBA mask.


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## jwk (Apr 20, 2013)

boerbull said:


> Here in the Netherlands almost every ambulance carries entonox, but not everybody uses it. We are only allowed to use it outside of the ambulance. Problem is that most medics here don’t believe it works because they have tried it and it doesn’t work. My experience is that it is great to use in combination with Fentanyl. It lowers the stress levels and allows the fentanyl to work better.
> I’ll use it for kids. For adults I prefer to use a combination of midazolam and esketamine if I know that I’m going to hurt them. That will knock them out just long enough to prepare them for transport. After that I use fentanyl during transport.



N2O + narcotic is approaching general anesthesia.  Not really something I'd promote for use in the field.  As for the idea that "it doesn't work" - well, that's either because they don't know what they're doing or their expectations are unrealistic.  You cannot administer N2O and expect to get total pain relief.


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## jwk (Apr 20, 2013)

Robb said:


> It's a demand valve mask so when they drop it it doesn't continuously flow, only when you breathe and create a vacuum in front of the mask, much like a SCBA/SCUBA mask.



There is still the issue of waste gases, whether y'all want to admit it or not.  We have very high air circulation rates in the OR, but we still are very concerned about waste anesthetic gases, including N2O, and our biomedical engineering guys test at least monthly for waste gas concentrations in the room.


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## Handsome Robb (Apr 20, 2013)

jwk said:


> There is still the issue of waste gases, whether y'all want to admit it or not.  We have very high air circulation rates in the OR, but we still are very concerned about waste anesthetic gases, including N2O, and our biomedical engineering guys test at least monthly for waste gas concentrations in the room.



I agree it is a concern but with the windows open, the HVAC system running and the exhaust fan system running I'd be willing to bet that we circulate more air relative to the size of the room through the back of the rig than your OR.


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## Rialaigh (Apr 20, 2013)

plain and simple why it isn't used in the south anymore...no real good way to keep track of it, had lots of providers huffing it every now and then for kicks.


I loved it, it's a great drug, worked great on entrapments or people who had bad femur fractures that we had to get on backboards and move. Was easy to quickly medicate them while we grabbed the rest of our equipment and that way moving them (or extricating a limb) was much less of a painful experience. Once in the bus we would get a line and give them versed with some narcotic and they wouldn't remember a thing from any of it. Seriously though, best med ever for extricating hands and arms from rollers and stuff in industrial settings.


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## the_negro_puppy (Apr 20, 2013)

We used to have it and now have methoxyflurane instead.







Works reasonably well, quick to use. Works really well for injuries or pain not requiring narcs and is really good for serious pain as you can have the patient on it in 10 seconds, getting analgesia while you get iv access and push morphine which can take a few minutes.

This combined with morphine can provide high levels of analgesia, had a pt with a midshaft # femur tell me he couldn't feel his leg.


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## jwk (Apr 20, 2013)

the_negro_puppy said:


> We used to have it and now have methoxyflurane instead.
> 
> 
> 
> ...



And you're one of the few places in the world that have it commercially available.  It's not available anywhere in the US.


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## Clare (Apr 21, 2013)

Entonox is a single cylinder here and we also have methoxyflurane but I've never used it, I don't understand why we have both really to be honest


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## CANDawg (Apr 21, 2013)

Clare said:


> Entonox is a single cylinder here and we also have methoxyflurane but I've never used it, I don't understand why we have both really to be honest



Single cylinder here too. Invert it a few times, hook up the mask, and away you go. It's also in our BLS scope here, which means EMTs can not have morphine but still have a pain management protocol.


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## chaz90 (Apr 21, 2013)

I love the concept of having some non narcotic analgesia available. Oh well, maybe one day it'll make it's way to the US.


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## MikeCivitello (Apr 22, 2013)

I would agree with Robb.  Working in an OR setting - with a continuous flow system is much different than what the Nitronox system is intended for and how it would be used.  OR settings and dental offices use continuous flow systems - and typically for long durations.  The Nitronox system is a demand flow system (gas only flows when the patient inhales) - and for short durations. 

JWKs point should not be disregarded whatsoever though - there should be a concern for occupational exposure - and the operators should ensure that they do have good fresh air circulation or venting if in the back of the ambulance.  In the hospital and dental settings - they should always be connected to a Vacuum source to vent the exhaled gas out of the building.  

Also - with regard to occupational exposure safety - the issues of nitrous oxide use have more to do with chronic exposure day in and day out.  There are small dosimeter detection badges that can be worn and submitted to testing agencies to report back 8 hour time weighted averages.


Quote:
Originally Posted by jwk  
There is still the issue of waste gases, whether y'all want to admit it or not. We have very high air circulation rates in the OR, but we still are very concerned about waste anesthetic gases, including N2O, and our biomedical engineering guys test at least monthly for waste gas concentrations in the room. 



Robb said:


> I agree it is a concern but with the windows open, the HVAC system running and the exhaust fan system running I'd be willing to bet that we circulate more air relative to the size of the room through the back of the rig than your OR.


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## MikeCivitello (Apr 22, 2013)

frdude1000 said:


> We have learned about Nitronox in my AEMT class.  I think the main problem is practicality (two separate bottles) as well as exposure risk.  The back of an ambulance is not a well vented place...the medication is self administered and the pt. will drop the mask once they have had enough.



Do not most ambulances have windows that can be opened and exhaust fans?  Also keep in mind - it is not a continous flow where added concerns would be if the patient removes the mask from their face or drops it.  The valve is closed until the patient inhales and then closes again when they stop inhaling.  

On practicality - all you are connecting is a hose with quick connect to your existing oxygen source.  The Nitronox system has a small cylinder of N20 (about a 20-30 minute supply) already connected to it.  To start using the system - connect to oxgyen, turn the N20 valve to open, and hand the mask to the patient.


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## Carlos Danger (Apr 22, 2013)

Robb said:


> I agree it is a concern but with the windows open, the HVAC system running and the exhaust fan system running I'd be willing to bet that we circulate more air relative to the size of the room through the back of the rig than your OR.



In the OR, the anesthesia circuits scavenge 99% of the gas that the patient exhales, whereas in the ambulance, it is all exhaled directly into the cabin. So even if the ambulance does have better air circulation than the OR, there will be far more gas circulating in the cabin of the ambulance than there is in the OR. 

in addition, the ambulance cabin is a lot less square footage than most OR's, meaning the potential exists for much higher gas concentrations.

I assume that as long as the exhaust fans are working properly there would be no issue, but IME, exhaust fans are one of those items that are often neglected and poorly maintained. 

At the implementation of a nitrous protocol, it would be wise to have the ambulances checked at the highest flows you'll use, to be sure that concentrations don't exceed the 50ppm standard, and also make sure that the fans are continually maintained. If it's not already required by state law.


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## Rialaigh (Apr 22, 2013)

I'm fairly certain it is not an issue of exposure. I know down here in the southeast it was an issue of provider usage and abusage (that rhymes..hehe..) that led to it being taken off the ambulances. There is no way to regulate amount used. If I am not mistaken there was an ambulance crash where it was determined both providers were nicely buzzed that resulted in the death of someone. 

It's a medication that has abusable potential with no easy way to strictly regulate usage, its not coming back in the US...


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## JPINFV (Apr 22, 2013)

MikeCivitello said:


> I would agree with Robb.  Working in an OR setting - with a continuous flow system is much different than what the Nitronox system is intended for and how it would be used.  OR settings and dental offices use continuous flow systems - and typically for long durations.  The Nitronox system is a demand flow system (gas only flows when the patient inhales) - and for short durations.




There's a few other points in regards to OR use. the patient is intubated and in a closed loop ventilator system with the exhaust going through scrubbers on the anesthesia machine. It's also combined both with other IV medications as well as other inhaled medications since the concentration needed to obtain anesthesia is too high (50% of people will not respond to a surgical incision to a mean aveolar pressure of 104 cm H2O. The rest of the gases the hospital I rotated through for anesthesia was less than 10. Which brings me to the other big point. When used in the OR, the end tidal concentration is measured the same way as CO2 is measured.


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## jwk (Apr 22, 2013)

JPINFV said:


> There's a few other points in regards to OR use. the patient is intubated and in a closed loop ventilator system with the exhaust going through scrubbers on the anesthesia machine. It's also combined both with other IV medications as well as other inhaled medications since the concentration needed to obtain anesthesia is too high (50% of people will not respond to a surgical incision to a mean aveolar pressure of 104 cm H2O. The rest of the gases the hospital I rotated through for anesthesia was less than 10. Which brings me to the other big point. When used in the OR, the end tidal concentration is measured the same way as CO2 is measured.



Most modern anesthesia systems are _semi-closed_, not closed.  Believe it or not, there is a big difference between the two.  

We use CO2 absorbers that remove CO2 only - O2, N2O, and anesthetic vapors are recirculated.

The 50% not responding to a surgical stimulus is MAC, for minimum alveolar concentration.  MAC is measured in percent of expired gas, and the easiest way to think of it is as an ED50.  That's why N2O alone is not capable of producing a surgical level of anesthesia, since 104% N2O is not physically possible.

EtCO2 is routinely measured in mmHg, and although most monitors have the capability to change the units, mmHg is the standard.  N2O is expressed in % because it is mixed in specific ratios with other gases, although again, some monitors are able to change the units.  I've never seen anyone use any other measurement for N2O - it would be far too confusing.

Not trying to be too picky, but units of measure are critically important.


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## JPINFV (Apr 23, 2013)

Sorry... minimum... brain fart on the medium vs minimum and the units. 

No worries on being picky either... tis important.

I've only seen N2O used either near the end of cases since it's breathed off much quicker than sevo, or as a quick boost. However the vast majority of cases at the hospital I rotated through was ran using sevo, or rarely des.


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## Handsome Robb (Apr 23, 2013)

Halothane said:


> In the OR, the anesthesia circuits scavenge 99% of the gas that the patient exhales, whereas in the ambulance, it is all exhaled directly into the cabin. So even if the ambulance does have better air circulation than the OR, there will be far more gas circulating in the cabin of the ambulance than there is in the OR.
> 
> in addition, the ambulance cabin is a lot less square footage than most OR's, meaning the potential exists for much higher gas concentrations.
> 
> ...



You bring up good points. 

My only real argument against it is we've had nitronox on the units for some time up until the last few years when we couldn't get parts and I work for a reputable company and in my experience the address issues that are similar to the ones you bring up as far as using it in the units. 

I'm interested to see if it comes back now that a system is again readily available. We still have the protocol for it. I generally will "bum" it off our ALS ski patrollers while we're still on scene picking a patient up from them while we work on an IV and get some fentanyl or morphine on board, works like a dream especially in kids. Our MD is huge on pain management. I might have to bring this to his attention.


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## MikeCivitello (Apr 23, 2013)

JPINFV said:


> There's a few other points in regards to OR use. the patient is intubated and in a closed loop ventilator system with the exhaust going through scrubbers on the anesthesia machine. It's also combined both with other IV medications as well as other inhaled medications since the concentration needed to obtain anesthesia is too high (50% of people will not respond to a surgical incision to a mean aveolar pressure of 104 cm H2O. The rest of the gases the hospital I rotated through for anesthesia was less than 10. Which brings me to the other big point. When used in the OR, the end tidal concentration is measured the same way as CO2 is measured.



I should have been more specific in my post - I typed one thing and was thinking something else!  

None of our nitrous oxide and oxygen systems are used the OR.  Outside of dental (and other private practice specialties) our systems are typically used in Emergency Departments, Radiology, and Oncology - where they are doing procedural sedations with nitrous oxide and oxygen.  Procedures that 15-30 minutes in length.  Patients are not intubated and conscious.  Our systems are intended for pain management and minimal to moderate sedation.  Administration is often done with a full facemask - but some still use the dental nasal hoods.


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## TheLocalMedic (Apr 23, 2013)

Okay, researched around a bit and here's what I found about Nitronox...

Apparently NIOSH wants there to be no more than 25 ppm of nitrous oxide in ambient air that providers are breathing, and even with scrubbers and good ventilation, there can be upwards of 150 ppm circulating in the ambulance.  Granted, this isn't approaching a therapeutic level where you're worried about getting goofy, but NIOSH is more concerned about the effects of long-term exposure for providers.  

That being said, I think it's wonderful stuff.  I've have both given it to patients and received it myself (after a gnarly arm fracture) and think that it's highly effective.  I wouldn't be concerned about having it on board my ambulance, except the other issue to contend with is the high abuse potential...


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## MikeCivitello (Apr 24, 2013)

TheLocalMedic said:


> Okay, researched around a bit and here's what I found about Nitronox...
> 
> Apparently NIOSH wants there to be no more than 25 ppm of nitrous oxide in ambient air that providers are breathing, and even with scrubbers and good ventilation, there can be upwards of 150 ppm circulating in the ambulance.  Granted, this isn't approaching a therapeutic level where you're worried about getting goofy, but NIOSH is more concerned about the effects of long-term exposure for providers.
> 
> That being said, I think it's wonderful stuff.  I've have both given it to patients and received it myself (after a gnarly arm fracture) and think that it's highly effective.  I wouldn't be concerned about having it on board my ambulance, except the other issue to contend with is the high abuse potential...



TheLocalMedic - 

NIOSH guidelines for nitrous oxide use are 25ppm time weighted average (TWA) for the duration of exposure.  ACGIH has a 50ppm guideline over an 8 hour TWA (which is typically the TWA protocol followed). 

Use of N20 where there is venting or good air circulation will minimize if not eliminate any potential exposure.

Can you share or cite where you found the "150ppm circulating in an ambulance"?  I would be curious to read more about that and how it was measured and under what circumstances.  Was this a documented study or just written somewhere?  Also want to see what they are referencing with regard to "scrubbers" as such a thing for N20 does not exist.  If someone could invent that they would really have something!

Bottom line - you can minimize the exposure by using in a well vented area and you can monitor exposure by wearing dosimeter badges periodically.

You are absolultey correct - it is the day in and day out chronic exposure that is the main concern.  Particularly with "dental" applications - they are leaning over the patient and working in the mouth.  If the patient exhales through their mouth (instead of into the nasal hood) - it is going right in the dentists and assistants face....  

N20 has been used for over 100+ years with a very high safety record.


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## Av8or007 (May 21, 2013)

With the abuse risk, why not just treat the n2o as a narcotic and sign in in and out for each shift w the weight of the entronox cylinder recorded. Place a numbered tag on the cylinder that seals it until used on a call. The log would just contain the medics names, the tag number, the pre and post shift tank mass and a yes/no box for if it was used on a call.


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## TheLocalMedic (May 21, 2013)

Av8or007 said:


> With the abuse risk, why not just treat the n2o as a narcotic and sign in in and out for each shift w the weight of the entronox cylinder recorded. Place a numbered tag on the cylinder that seals it until used on a call. The log would just contain the medics names, the tag number, the pre and post shift tank mass and a yes/no box for if it was used on a call.



^^ This


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## Handsome Robb (May 21, 2013)

Av8or007 said:


> With the abuse risk, why not just treat the n2o as a narcotic and sign in in and out for each shift w the weight of the entronox cylinder recorded. Place a numbered tag on the cylinder that seals it until used on a call. The log would just contain the medics names, the tag number, the pre and post shift tank mass and a yes/no box for if it was used on a call.



I'm pretty sure that's how they used to do ours before it went away.


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## Clare (May 21, 2013)

We've successfully used entonox for nearly forty years with no problem so um yeah about the risk of people huffing it ...


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## Craig Alan Evans (Jun 27, 2013)

We have used it for close to 20 years now with great success.


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## Galveston CFRN (Nov 19, 2013)

*Low Tech solution to accidental crew inhalation of NO*

I'm sure this isn't original, but it hasn't been mentioned.....
Crew in the back of the bus dons NRB or Simple O2 masks coming from onboard regulators....Common sense would yield increased FiO2 and dilution will prevent potential NO effect on caregivers in cabin. Combined with good cabin ventilation this should be enough to satisfy any OSHA concerns....this might work with extended contact as well (as in conscious sedation procedures in ED)....It deserves a second look, as Nitronox remains a useful and mostly harmless adjunct in EMS/ED analgesia and anxiolysis (apologies for spelling/grammar if incorrect). Glad to see that there are folks that still believe in this as a useful tool in the box!! Best Regards....Layne in Galveston, TX


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