Nitrous oxide

RE: Nitrous oxide

svn — Wed, 20 Jul 2016 22:29:55 GMT

[quote user="Niall Taylor"]

[quote user="svn"]Sp02? Capnography is what you need if you are using N20![/quote]

Can you explain?

Niall

[/quote]

I'm too hot to think right now! I find Sp02 monitors to be compulsive liars, I can't remember why I have that stuck in my brain about capnograhy, could possibly be getting confused with the need to use it in rebreathing circuits with N20 - ask me again in winter :p

RE: Nitrous oxide

Niall Taylor — Wed, 20 Jul 2016 10:44:19 GMT

[quote user="svn"]Sp02? Capnography is what you need if you are using N20![/quote]

Can you explain?

Niall

RE: Nitrous oxide

svn — Wed, 13 Jul 2016 20:40:16 GMT

Sp02? Capnography is what you need if you are using N20! What circuits do you use?

RE: Nitrous oxide

svn — Wed, 13 Jul 2016 20:38:38 GMT

10 minutes off N20 is what I was taught in my first job, and at college, and is what I have always stuck to. Last 2-3 minutes off inhalant on pure O2 before disconnection and transferring to recovery

RE: Nitrous oxide

dachsie_4 — Wed, 13 Jul 2016 17:18:41 GMT

Thank you for the responses

RE: Nitrous oxide

Clive Ansell — Wed, 13 Jul 2016 11:41:30 GMT

One of my regular practices still uses nitrous oxide, and we normally turn off as the last few sutures are placed. It is often much less than 5 minutes, and sometimes even gets forgotten until the last minute - they use pulse oximetry and I have never yet seen a case where SpO2 levels drop significantly when nitrous is turned off.

RE: Nitrous oxide

Iain Richards — Wed, 13 Jul 2016 08:29:12 GMT

[quote user="dachsie_4"]

More pieces to the puzzle : according to nikki Grint a vet anaesthetist N2O disperses immediately when switched off and patient left on 100% oxygen (???) So when asked how long needs to be on oxygen for the reply was 5min. So if animal takes 5min to wake up once iso switched off, one can switch iso and N2O off at same time.

Regards

Monika

[/quote]I'd agree with that. N20 is so insoluble it diffuses into the alveoli faster than the other gases so its partial pressure rises fast, reducing the partial pressure of O2. By ensuring that the fresh gas flow of O2 is increased, you help increase the PP of O2 (so if 2 N20:1 O2, the FGF of O2 needs to rise to 3 - hence your 100% O2).

Yes, if your animal takes 5 min to wake up, all is well. But with isoflo and good analgesia and a quality RVN on the front end, it can be less than that.

RE: Nitrous oxide

dachsie_4 — Tue, 12 Jul 2016 23:06:30 GMT

Regards

Monika

RE: Nitrous oxide

dachsie_4 — Tue, 12 Jul 2016 21:46:12 GMT

I shall ask the nurse who ran the course and will get back to you

Monika

RE: Nitrous oxide

Chris Barker — Tue, 12 Jul 2016 20:50:04 GMT

We used to have an ex-hospital monitor which measured nitrous oxide in the exhaled breath. Suffice to say that five minutes of oxygen sans nitrous at the end of a procedure was sufficient to reduce the levels of nitrous in exhaled breath to negligible levels. Is it worth doing? S'pose the argument for doing so is first to reduce potential hypoxaemia as the nitrous floods out of the blood into the alveoli and second to prevent human exposure to exhaled nitrous in the recovery area.

RE: Nitrous oxide

Iain Richards — Tue, 12 Jul 2016 20:38:31 GMT

OK, curious. I'd like to know more please. It might be they are saying that the concept of diffusion hypoxia occurs but has less of an effect than previously thought. This might relate to better pulse oximeters showing saturation is normal. CAn you find out a bit more please (or let me know who did ht ecourse and I'll ask directly)

Iain

RE: Nitrous oxide

dachsie_4 — Tue, 12 Jul 2016 18:52:18 GMT

Thank you I have tried to look up as well and with my limited pubmed access could not find a satisfactory answer either. The question cropped up when one of our nurses came back from an anaesthetic cpd saying there's no need to wait at all? ??

Regards

Monika

RE: Nitrous oxide

Iain Richards — Tue, 12 Jul 2016 13:39:54 GMT

I'm not aware it's changed. About 5 minutes of increased oxygen. If I have a quiet surgery, I might look it up.

So - quiet surgery. No precise figure, but one report of children given entonox showed reported side effects gone within 5 minutes of ceasing inhalalation.