N2O & nausea

[turnupthevapor]

nitrous, ponv & nausea? I am looking to clear up a little issue in my mind. I think we will all agree that N2O if used for a long case will increase the risk of ponv (nnt 9 after 2 hrs of exposure). My question however, does adding an antiemetic somehow bring the risk back to the risk if you hadn't used the nitrous at all (as my associate swears by this). Question number two is is N2O worse than VA.

For example would y'all put the ponv risk as follows:

prop < VA < prop / n20 < n20/va

Or

prop < VA ~ prop / n20 < n20/va


Thanks in advance


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[deleted9493]

As the article in Anesthesiology's May issue pointed out, PONV seems to only be significantly increased after an hour's use of nitrous oxide. It would seem that the underlying mechanism there is from gassy distention of enclosed spaces (e.g. middle ear, small bowel). I wouldn't think that antiemetics would have a significant effect if there is nausea from an ongoing source of distention.

So yeah, in my mind, the answer to your categorization is dependent upon how long you're using it in the case. Usually my only uses for it are inhalation inductions, as a bridge to emergence, and during OB generals in which minimizing volatile is helpful for uterine contraction after placental delivery.

 

[Ignatius J]

Hudson, do you have a link to that article? I missed that one but want to share it with colleagues. That may change things for me on emergence. I've always avoided it.

 

[deleted9493]

Sure:
http://journals.lww.com/anesthesiol...xide_related_Postoperative_Nausea_and.22.aspx

 

[BLADEMDA]

Hudson, do you have a link to that article? I missed that one but want to share it with colleagues. That may change things for me on emergence. I've always avoided it.

Nitrous Oxide is fantastic for emergence. It allows one to practically turn off the vapor and has the added value of the second gas effect with wake-up as well.


http://www.ncbi.nlm.nih.gov/pubmed/21270630

 

[OB1🤙]

I partially agree. I think it's great for sevo (or iso) emergence.

Not necessary with desflurane though.

Nitrous Oxide is fantastic for emergence. It allows one to practically turn off the vapor and has the added value of the second gas effect with wake-up as well.


http://www.ncbi.nlm.nih.gov/pubmed/21270630

 

[Jay K]

My question however, does adding an antiemetic somehow bring the risk back to the risk if you hadn't used the nitrous at all (as my associate swears by this).

Unless contraindicated I regularly administer antiemetic prophylaxis to patients; Unless contraindicated I regularly administer N2O/VA.

If my patients consistently experienced PONV, I would not practice as I do. The PACU RN's would have certainly told me long ago, particularly since I poll them regularly.

 

[risnwb]

I partially agree. I think it's great for sevo (or iso) emergence.

Not necessary with desflurane though.

Definitely not necessary, but even though the des comes off quick, I find the nitrous wakeup is way smoother, esp it the patient is nice and narcotized...


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[BLADEMDA]

I'm not a big Nitrous Oxide Fan. I use it on kids and for emergence (last 30-45 minutes of a case). I too believe in Anti-emetic prophylaxis to EVERY patient presenting for surgery. I give MULTIPLE Anti-Emetic prophylaxis to those patients at risk of N/V or a history of N/V. For Severe N/V I give EVERYTHING on Formulary (for GA with Volatile agents) or consider TIVA/Regional whenever feasible.

 

[BLADEMDA]

What We Already Know about This Topic
• The inclusion of nitrous oxide as a component of inhalational
anesthesia has been observed to increase the likelihood of
postoperative nausea and vomiting
What This Article Tells Us That Is New
• Duration of exposure to nitrous oxide less than 1 h has little
effect on the rate of postoperative nausea and vomiting
• The risk ratio for postoperative nausea and vomiting increases
approximately 20% per hour after the first 45 min of exposure
to nitrous oxide


http://journals.lww.com/anesthesiol...xide_related_Postoperative_Nausea_and.22.aspx


I try to limit my Nitrous Oxide exposure for patients to 45 minutes or less.