Nitrous Oxide and Anesthetics

I am little confused on the use of nitrous oxide.

  1. I have been reading Wikipedia. The different articles and different sections seem to be contradictory. Is it only an analgesic or can it also be used as an an anesthetic? Sometimes it calls it an anesthetic, and other times they say it is not strong enough to be one. Maybe this hinges on the definition of a “general anesthetic.” I was of the opinion that a general anesthetic knocks you out. Either you are or are not.

  2. It is commonly used in conjunction with with stronger anesthetics. If you have a stronger anesthetic, what is the purpose of the nitrous oxide? From Wikipedia:

“However, nitrous oxide was not found to be a strong enough anaesthetic for use in major surgery in hospital settings. Being a stronger and more potent anaesthetic, sulfuric ether was instead demonstrated and accepted for use in October 1846, along with chloroform in 1847.[8] When Joseph Thomas Clover invented the “gas-ether inhaler” in 1876, it however became a common practice at hospitals to initiate all anaesthetic treatments with a mild flow of nitrous oxide, and then gradually increase the anaesthesia with the stronger ether/chloroform. Clover’s gas-ether inhaler was designed to supply the patient with nitrous oxide and ether at the same time, with the exact mixture being controlled by the operator of the device. It remained in use by many hospitals until the 1930s.[14] Although hospitals today are using a more advanced anaesthetic machine, these machines still use the same principle launched with Clover’s gas-ether inhaler, to initiate the anaesthesia with nitrous oxide, before the administration of a more powerful anaesthetic.”

It’s not really a pain killer, it just makes you kind of wonky and, honestly, I think it makes life easier for the dentist since he can work in your mouth without you really paying attention (or gagging as much). Last time I had a wisdom tooth pulled, they used it more so they could get the Novocaine in a little easier. Next time I’ll opt to not have it. I really don’t mind needles and, as much as I liked NO in college, it’s one thing to go up and back down 15 seconds later, going WAAAAY up and staying there for 10 minutes is very different. I had them turn it off before they started pulling the tooth.

Here’s a nice professional review:

The big advantages of N2O are that it is the fastest known anesthetic, so it works really really fast, and it is among the safest, so you don’t have to worry too much about a little too much. Which, presumably, is one major reason dentists use it, so they don’t need to have a (very expensive) anesthesiologist on hand.

Its major drawback is that it isn’t possible to reliably and safely get people wholly sedated with it, meaning not just to the point of unconsciousness but to where they won’t react if you start cutting into them, which is probably connected with its safety – meaning, because it isn’t that potent, you can’t easily overdose on it.

I’ve heard one thing that dentists have to remember is that if they want to play around with it (after work) they need to NOT strap the mask on. That way if they pass out, the mask falls off. From time to time you’ll hear about a dentist accidentally killing himself that way.

Safe is a relative term. Last time I had it, my dentist gave me too much. I got nauseous and it really messed my head up for about a half hour after (and not in the ‘good’ nitrous way). I did not like it, but it passed. But it isn’t unsafe like normal anesthetics can be when over applied (coma, death, death-like symptoms).

Entonox (half oxygen and half nitrous oxide) is carried here by all paramedics for use as pain relief. It is also the pain relief of choice for women giving birth.

A few years ago I had a compound fracture of my tib and fib after being run over by a fork lift truck. I can tell you, from first hand experience, that it really does work. Of course the morphine kicked in after a while, but the gas and air worked a treat while they worked on me.

In my experience, I still had pain while on Nitrous - but I didn’t care. It caused a dissociative state in which my brain still registered pain but I had no emotional or physical reaction to it. The dentist asked me if I had pain when he poked my gums - and I did - but my answer was a giggle. He pulled my wisdom teeth and I didn’t care one whit while he was doing it.

urban legend, unless the flowmeter is messed up you can’t turn the N2O above 70% so you still have 30% O2 which is slightly more then atmospheric

Yes the two biggest benefits of N20 are that you loose track of time and you don’t care about things. Of course we always make sure we have anethesia using a local and just use the N2O to relax the patient.

I’ve noticed over the past 10 (20?) years or so, that hardly any dentists use nitrous oxide any more. (ETA: Even for more invasive procedures like root canals and abcess excisions :eek: ) When I asked a dentist once, he told me that there are strict regulations that there didn’t used to be, requiring much more training before a dentist is allowed to use it. (This is in California.) So most dentists just quite using it.

I had heard that using nitrous oxide could be a little bit dangerous, and some patients had suffered some lasting neurological damage because the dentists weren’t careful enough about the dosage or the mixture. That’s apparently what all the extra training and certification requirements were about.

Anybody know about this? rsat3acr?

Anyone have any idea the answer to my second question?

Why is it used in conjunction with other stronger anesthetics? This seems like taking a ibuprofen for pain along with a big dose of morphine. Just skip the ibuprofen.

Ibuprofen reduces swelling, morphine (or more likely hydrocodone) makes you wonky while the ibuprofen does it’s job.

Can’t speak for the CA rules but in TX I don’t think they are a big deal.

As for neurological damage, yes that can happen. I think it is very rare these days. Usually in long term exposure, so dental people are at greater risk than the patients. Don’t think it is a problem the flow meters won’t allow too much N2O and the masks all suction up the exhaled N2O from the patient. I think that the local anesthetic is probably more dangerous than N2O. Of course like all meds etc one must weigh the bad against the good.

Another issue is spontanious abortion in women. We don’t use it on pregnent patients of have preg. assistant administer it. Of course they used to give it to women in labor.

I’m very hard to numb fully. Using nitrous I don’t really mind the pain so much because I can concentrate on the floaty feeling from the gas.

And I really hate needles.

This is also discussed in the review I cited above. In brief, there are a number of desirable qualities in general anesthesia, to wit you want the patient to go to sleep quickly, be sufficiently numb that cutting into him does not wake him and does not even trigger autonomic evidence of distress (accelerated heart rate, blood pressure rise), has his voluntary muscles paralyzed so he doesn’t move around even randomly and cause the surgeon to cut this instead of that, and not remember anything when he wakes up. No one medication can do all of these things, so they use various combinations. The N2O fulfills the first requirement, putting the patient to sleep quickly and safely. Other anesthetics provide deep painkilling, so he won’t wake up even if you crack open his chest and cut his heart out or pieces of his liver. Others wipe out his memory, just in case something seeps in there. Still others will paralyze him, and some may reduce inflammation and swelling immediately afterward.

The actual mechanism of CNS anesthesia is not known, so we don’t even know if all “anesthetics” act in the same way. Mechanisms of analgesia (pain relief) are better understood, and we know they don’t all act the same way, and don’t have the same spectrum of effects. So I think it’s probably a mistake to think of “anesthetic” as just a one-dimensional line, with stronger to the right and weaker to the left. It’s more like each drug has its own three or four dimensions, and varying strength along them.