Thoughts on nitrous

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sigrhoillusion

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What are everyone's thoughts on this drug? Not going to lie, I rarely if ever used it during residency outside of stat GA C-sections, and only really began using it in peds fellowship for the induction.

So supervising a total laryngectomy on a 74yo patient with a cardiac history. CRNA had him on a good amount of volatile but patient kept "moving" (I think it was more bucking do to the airway manipulation by the surgeon). Despite this apparent bucking this patient's BP which started in the 150/90s was hovering in the 80-90s systolics with MAPs dipping into the 60s. Added a remifentanyl infusion in the background to help try to blunt the stimuli, but CRNA said that he still occasionally was bucking. And again despite this his BP kept dipping. Oh and of course the surgeon was monitoring the patient, so for the first half of the surgery we couldn't use muscle relaxants. So the record (like a lot of ENT cases with varying amounts of stimuli throughout the case, looked like a rollercoaster ride)

So I get relieved for the day around 4pm and give my signout to the next anesthesiologist. And he looks at the record and says what's up with the waves. I tell him about the BP and the bucking. And he just says, "Why didn't you just start nitrous!?" the patient is clearly not anesthetized. He then goes on about how properly anesthetized patients don't move, and that when the surgeon was done monitoring and we were allowed to use muscle relaxants we were only covering up a light anesthetic and risked recall. While I do agree taht the incidence of recall is higher when relaxants are used, I highly doubt a 74yo patient who was on 2%+ of sevoflurane plus a remifentanyl infusion who had a low BP has any significant chance of recall. I felt the problem was the fact that surgeon was manipulating the airway and the MAC needle to blunt intubation is closer to 1.3...

So does anyone else think that this 74yo cardiac patient was lightly anesthetized or that the magical solution was turning on the nitrous? Forgot to mention that the CRNA was pregnant (not sure how much this facotrs into anything, but why risk it). I dunno, just never been a fan of nitrous, and it seems like more recent articles are showing that outcomes are poorer with its use. Just feeling a little bad, cause this anesthesiologist sort of dressed me down in front of a couple colleagues, as if I had never read about the miracle drug known as nitrous...

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I'm a senior resident and a huge fan and user of Nitrous Oxide. I completely agree with your management and doubt there was any recall. I don't think Nitrous would've been a miracle drug, especially if you had already started Remi and that wasn't helping. Nitrous has been proven safe in patients with cardiac disease undergoing noncardiac surgery (ENIGMA II trial), so it likely would have been safe from a cardiac perspective in this patient. It causes less hemodynamic effects than Sevo but I doubt it would've helped with bucking. Also, Nitrous is an oxidizer like Oxygen so running high Nitrous in a laryngectomy case would predispose the patient to airway fires when working around/in the airway.

I would've cranked up the Remi and started a Phenylephrine infusion to support BP PRN had I been in there.
 
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I'm not a huge fan of nitrous but it has it's uses. PONV risk tends to keep my away from it for the most part. Peds inductions I use it and old nearly dead people that need an anesthetic but can't tolerate much. The other time I use it is during c-sections that have less than perfect regional anesthesia and the baby isn't out yet, just give them a mask and ask them to take a few deep breaths (gets rid of pain but doesn't depress the baby).

For your original case I'd have really cranked up the remi dose as that is the type of case it is perfect for (hugely stimulating, not terribly painful afterwards). Deep narcotic anesthetic is nice for the hemodynamic stability. You weren't risking awareness with the patient moving given your regimen and I'm not sure why an anesthesiologist would claim that. That's like the surgeon telling me the patient is awake when they move during a case.
 
I'm not a huge fan of nitrous but it has it's uses. PONV risk tends to keep my away from it for the most part. Peds inductions I use it and old nearly dead people that need an anesthetic but can't tolerate much. The other time I use it is during c-sections that have less than perfect regional anesthesia and the baby isn't out yet, just give them a mask and ask them to take a few deep breaths (gets rid of pain but doesn't depress the baby).

For your original case I'd have really cranked up the remi dose as that is the type of case it is perfect for (hugely stimulating, not terribly painful afterwards). Deep narcotic anesthetic is nice for the hemodynamic stability. You weren't risking awareness with the patient moving given your regimen and I'm not sure why an anesthesiologist would claim that. That's like the surgeon telling me the patient is awake when they move during a case.

I think this guy is one of the older guys who doesn't know why anesthesia practice has changed at all over the past 20 years. I mean it's not like people were dying left and right back then (which truthfully they weren't) so why try to improve on our craft...? And I agree we did start going up on the remi. Then the surgeon was done monitoring so we started using the relaxant anyways.
 
I mostly use Nitrous at the end of a case for waking the patient up quickly. No increased risk of PONV when used for less than one hour.

http://www.ncbi.nlm.nih.gov/pubmed/24401771

BACKGROUND:
Inclusion of nitrous oxide in the gas mixture has been implicated in postoperative nausea and vomiting (PONV) in numerous studies. However, these studies have not examined whether duration of exposure was a significant covariate. This distinction might affect the future place of nitrous oxide in clinical practice.

METHODS:
PubMed listed journals reporting trials in which patients randomized to a nitrous oxide or nitrous oxide-free anesthetic for surgery were included, where the incidence of PONV within the first 24 postoperative hours and mean duration of anesthesia was reported. Meta-regression of the log risk ratio for PONV with nitrous oxide (lnRR PONVN2O) versus duration was performed.

RESULTS:
Twenty-nine studies in 27 articles met the inclusion criteria, randomizing 10,317 patients. There was a significant relationship between lnRR PONVN2O and duration (r = 0.51, P = 0.002). Risk ratio PONV increased 20% per hour of nitrous oxide after 45 min. The number needed to treat to prevent PONV by avoiding nitrous oxide was 128, 23, and 9 where duration was less than 1, 1 to 2, and over 2 h, respectively. The risk ratio for the overall effect of nitrous oxide on PONV was 1.21 (CIs, 1.04-1.40); P = 0.014.

CONCLUSIONS:
This duration-related effect may be via disturbance of methionine and folate metabolism. No clinically significant effect of nitrous oxide on the risk of PONV exists under an hour of exposure. Nitrous oxide-related PONV should not be seen as an impediment to its use in minor or ambulatory surgery.
 
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Your colleague is an unprofessional dip****. And no, lack of nitrous was not your problem.

That being said, I really like nitrous. I bet you more nitrous has been given to pts than all other anesthetic agents combined over the last 150yrs. I use for wakeups on the vast majority of my GETA's as a tool to get rid of the volatile. Keep it to less than 30-45mins at 60-65% and PONV is a non-issue. Longer than that and nausea starts to become a factor. I don't use it for maintenance for this reason.
 
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I mostly use Nitrous at the end of a case for waking the patient up quickly. No increased risk of PONV when used for less than one hour.

I agree a brief exposure to nitrous doesn't significantly increase PONV. Then again, you also don't need it to wake a patient up on a dime. Nitrous does have other deleterious effects beyond just PONV, though, so I tend to not use it much.
 
Your colleague is an unprofessional dip****. And no, lack of nitrous was not your problem.

That being said, I really like nitrous. I bet you more nitrous has been given to pts than all other anesthetic agents combined over the last 150yrs. I use for wakeups on the vast majority of my GETA's as a tool to get rid of the volatile. Keep it to less than 30-45mins at 60-65% and PONV is a non-issue. Longer than that and nausea starts to become a factor. I don't use it for maintenance for this reason.

Yea I don't think starting nitrous 3-4 hours into a possible 7 hour case was going to be a great solution either. Never really had an issue with wakeups not using nitrous either. That being said, now that I'm supervising i feel like wakeups can be a crapshoot since I'm not in the room the last 30 minutes trying to perfect it. The struggle is real... haha
 
Nitrous was not going to be the savior you were looking for. As others have said, you needed to jack up your remi and start a phenylephrine infusion. Very few people buck on .2+ of remi.
 
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What are everyone's thoughts on this drug? Not going to lie, I rarely if ever used it during residency outside of stat GA C-sections, and only really began using it in peds fellowship for the induction.

So supervising a total laryngectomy on a 74yo patient with a cardiac history. CRNA had him on a good amount of volatile but patient kept "moving" (I think it was more bucking do to the airway manipulation by the surgeon). Despite this apparent bucking this patient's BP which started in the 150/90s was hovering in the 80-90s systolics with MAPs dipping into the 60s. Added a remifentanyl infusion in the background to help try to blunt the stimuli, but CRNA said that he still occasionally was bucking. And again despite this his BP kept dipping. Oh and of course the surgeon was monitoring the patient, so for the first half of the surgery we couldn't use muscle relaxants. So the record (like a lot of ENT cases with varying amounts of stimuli throughout the case, looked like a rollercoaster ride)

So I get relieved for the day around 4pm and give my signout to the next anesthesiologist. And he looks at the record and says what's up with the waves. I tell him about the BP and the bucking. And he just says, "Why didn't you just start nitrous!?" the patient is clearly not anesthetized. He then goes on about how properly anesthetized patients don't move, and that when the surgeon was done monitoring and we were allowed to use muscle relaxants we were only covering up a light anesthetic and risked recall. While I do agree taht the incidence of recall is higher when relaxants are used, I highly doubt a 74yo patient who was on 2%+ of sevoflurane plus a remifentanyl infusion who had a low BP has any significant chance of recall. I felt the problem was the fact that surgeon was manipulating the airway and the MAC needle to blunt intubation is closer to 1.3...

So does anyone else think that this 74yo cardiac patient was lightly anesthetized or that the magical solution was turning on the nitrous? Forgot to mention that the CRNA was pregnant (not sure how much this facotrs into anything, but why risk it). I dunno, just never been a fan of nitrous, and it seems like more recent articles are showing that outcomes are poorer with its use. Just feeling a little bad, cause this anesthesiologist sort of dressed me down in front of a couple colleagues, as if I had never read about the miracle drug known as nitrous...

Neo drip.
Hyperventilate the guy to ETCO2 28-30.
Narcotize him (remi or morphine or dilaudid, whatever).
Precedex if available.

Your colleague was right in the sense that you have a patient who needs more anesthesia to meet the needs of the surgery, which would then require a neo drip. You dont determine an appropriate anesthetic depth for a particular case based on the old guys BP, you give enough anesthesia to meet the needs of the case and cover vasodilation with pressors.

I love using nitrous for lots of cases. Mainly ortho/ENT room, fast wake ups, I personally dont see PONV increased with antiemetics and 50/50 mix in oxygen. The beauty of nitrous is that its like remi in that it is a continuous analgesic that magically goes away when turned off. PAIN is whats making this guy move, your hypnotic component is probably ok. So cover it with either nitrous or more narcotic, and cover the resultant low bp that follows the analgesia with pressor.
 
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The analgesic properties of nitrous are abolished when given in combination with a volatile. There's a good paper out there that details the mechanism.
 
Neo drip.
Hyperventilate the guy to ETCO2 28-30.
Narcotize him (remi or morphine or dilaudid, whatever).
Precedex if available.

Your colleague was right in the sense that you have a patient who needs more anesthesia to meet the needs of the surgery, which would then require a neo drip. You dont determine an appropriate anesthetic depth for a particular case based on the old guys BP, you give enough anesthesia to meet the needs of the case and cover vasodilation with pressors.

I love using nitrous for lots of cases. Mainly ortho/ENT room, fast wake ups, I personally dont see PONV increased with antiemetics and 50/50 mix in oxygen. The beauty of nitrous is that its like remi in that it is a continuous analgesic that magically goes away when turned off. PAIN is whats making this guy move, your hypnotic component is probably ok. So cover it with either nitrous or more narcotic, and cover the resultant low bp that follows the analgesia with pressor.

To be fair, the bucking was mostly before adding the remi. After that, the only issue was trying to keep the pressures up. After numerous neo boluses a drip was started. My biggest question was on the nitrous and if this would have magically solved all the problem from the get go.

Do people find that using nitrous significantly improves BP issues. I remember giving lunches/breaks to co-workers in residency and they'd use that aa reason they were running nitrous during the case, but never felt it made that much of a difference.
 
To be fair, the bucking was mostly before adding the remi. After that, the only issue was trying to keep the pressures up. After numerous neo boluses a drip was started. My biggest question was on the nitrous and if this would have magically solved all the problem from the get go.

Do people find that using nitrous significantly improves BP issues. I remember giving lunches/breaks to co-workers in residency and they'd use that aa reason they were running nitrous during the case, but never felt it made that much of a difference.

Only makes a difference if you then cut the volatile by 1/2. Even then it's hit or miss.
 
I like nitrous and use it often. I think it has become underutilized due to fear of PONV. It is great for short, ambulatory, "LMA-type" cases. I also turn on the nitrous after a long case to get rid of the volatile. I use it in old people a lot because there is less hypotension and they don't get PONV. It's cheap.

A downside to nitrous is that it is probably one of the worst greenhouse gases out there.

I don't think nitrous would have prevented the bucking in it of itself. It does sound like the patient was under-anesthetized, so adding nitrous would have only helped in the sense that it would have gotten the patient deeper. Remi is a good choice for these types of cases and is one of the few uses that I can think of for remi. It sounds like it was a late in the day case, so the patient was probably a little dry. Get the patient deeper any way you see fit, give a bolus of fluid, and ride it out with a phenylephrine drip.
 
If I have old frail patients under GA that won't tolerate small amounts of sevo I'll add nitrous and put them on a whiff of volatile. Works well for BP issues and PONV is not much of a factor in these patients. No one has ever complained of awareness to date.
 
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Only makes a difference if you then cut the volatile by 1/2. Even then it's hit or miss.

This. We did quite a few big total laryngectomy/neckectomies with free flaps at my residency program and we often used nitrous along with remi to try and keep BPs up by cutting back on our volatile. Skeptical that adding nitrous to your 2% sevo was going to do anything for movement, though. Our surgeons would get very upset if we used even a little pressor as they felt it compromised their flap.
 
If I have old frail patients under GA that won't tolerate small amounts of sevo I'll add nitrous and put them on a whiff of volatile. Works well for BP issues and PONV is not much of a factor in these patients. No one has ever complained of awareness to date.

Agree 100%. Only time I ever use it is to spare giving volatile anesthetic to patients who are ancient and can't tolerate a concentration of volatile that will stop movement during surgery and prevent recall. I understand the rationale behind "fast wakeups" using nitrous, but the reality is that if you understand the pharmacokinetics of the other anesthetics you're using, you can wake patients up expeditiously without nitrous, regardless of how long the surgery is.

On a side note but somewhat related, I am convinced that 99.9% of slow wakeups are due to overly narcotizing patients during the case.
 
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To be fair, the bucking was mostly before adding the remi. After that, the only issue was trying to keep the pressures up. After numerous neo boluses a drip was started. My biggest question was on the nitrous and if this would have magically solved all the problem from the get go.

Do people find that using nitrous significantly improves BP issues. I remember giving lunches/breaks to co-workers in residency and they'd use that aa reason they were running nitrous during the case, but never felt it made that much of a difference.

I dont believe that 1 MAC of 50% nitrous plus sevo or 1 MAC of sevo alone has any difference on BP....IMO it makes your roller coaster record look less bumpy
 
I like nitrous and use it often. I think it has become underutilized due to fear of PONV. It is great for short, ambulatory, "LMA-type" cases. I also turn on the nitrous after a long case to get rid of the volatile. I use it in old people a lot because there is less hypotension and they don't get PONV. It's cheap.

A downside to nitrous is that it is probably one of the worst greenhouse gases out there.

I don't think nitrous would have prevented the bucking in it of itself. It does sound like the patient was under-anesthetized, so adding nitrous would have only helped in the sense that it would have gotten the patient deeper. Remi is a good choice for these types of cases and is one of the few uses that I can think of for remi. It sounds like it was a late in the day case, so the patient was probably a little dry. Get the patient deeper any way you see fit, give a bolus of fluid, and ride it out with a phenylephrine drip.

Agree. I use it a lot on ambulatory cases. Love it.
 
Agree 100%. Only time I ever use it is to spare giving volatile anesthetic to patients who are ancient and can't tolerate a concentration of volatile that will stop movement during surgery and prevent recall. I understand the rationale behind "fast wakeups" using nitrous, but the reality is that if you understand the pharmacokinetics of the other anesthetics you're using, you can wake patients up expeditiously without nitrous, regardless of how long the surgery is.

On a side note but somewhat related, I am convinced that 99.9% of slow wakeups are due to overly narcotizing patients during the case.
Totally agree. Too much opiate ... and for shorter cases, unnecessary midazolam.

The only times I've used nitrous in the last few years was for peds inductions, OB GA, and if a resident wanted to use it (which is fine). I just never felt it added much to my anesthetics.
 
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Lemme just point out that nitrous was being raised as a solution to this problem: I'm doing a head & neck case, I'm running only volatile, I can't use neuromuscular blockers, the BP is in the toilet, and the patient keeps bucking.

Nitrous.

As the solution to this problem.:rolleyes:
 
Midazolam is by far the most overused drug our Crna colleagues use. Anybody using remi in the bronch suites. Yesterday I had a 70 y/o in afib ef 25% 7.4/50/50 on 6l nasal cannula with bilateral bronchopulumonary pneumona in hypoxic/hypercapnic respiratory failure with an inr of 3.2. I thought remi would be great for case as any impairment of respiratory drive would send his physiology into severe failure. Remi??? Sorry for the threadjack.
 
Midazolam is by far the most overused drug our Crna colleagues use. Anybody using remi in the bronch suites. Yesterday I had a 70 y/o in afib ef 25% 7.4/50/50 on 6l nasal cannula with bilateral bronchopulumonary pneumona in hypoxic/hypercapnic respiratory failure with an inr of 3.2. I thought remi would be great for case as any impairment of respiratory drive would send his physiology into severe failure. Remi??? Sorry for the threadjack.

Precedex?
 
A downside to nitrous is that it is probably one of the worst greenhouse gases out there.

Agreed. But I believe Desflurane is worse on a kilogram per kg/CO2 produced basis. And it's hard to quantify nitrous solely from scavenger system within the OR, considering that it is also used in food industry and certain manufacturing facilities.


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