Opioid dosing under GA

[deleted875186]

This may seem a little basic, but I’m a resident and am curious how most people dose their opioids. I generally don’t give any long acting opioids for cases without significant post op pain. For cases where they’ll need post op analgesia, I usually dose some long acting opioids at the start of GA because I think it lets me use less fentanyl and smoothes out the hemodynamics. So long as it’s a modest dose, I haven’t had anyone yet that fails to breath by the end of the surgery. Do others do the same? I’ve had a lot of attendings that want to wait until the end of the case and titrate to respiratory rate.

---

Members don't see this ad.

 

[Psai]

Opioid free baby

 

[anbuitachi]

This may seem a little basic, but I’m a resident and am curious how most people dose their opioids. I generally don’t give any long acting opioids for cases without significant post op pain. For cases where they’ll need post op analgesia, I usually dose some long acting opioids at the start of GA because I think it lets me use less fentanyl and smoothes out the hemodynamics. So long as it’s a modest dose, I haven’t had anyone yet that fails to breath by the end of the surgery. Do others do the same? I’ve had a lot of attendings that want to wait until the end of the case and titrate to respiratory rate.

depends on the case. for painful cases usually 3-5 mcg/kg on induction. But usually for a skinny person like 250mcg fentanyl, then infusion of 3mcg/kg per hour.

some people like to dose 'longer' acting opioids in at the end for more post op control. however fentanyl has a long context sensitive half life if you reach an decent level, so to me that's enough. they pain is usually well controlled for hours after extubation

 

[Psai]

depends on the case. for painful cases usually 3-5 mcg/kg on induction. But usually for a skinny person like 250mcg fentanyl, then infusion of 3mcg/kg per hour.

some people like to dose 'longer' acting opioids in at the end for more post op control. however fentanyl has a long context sensitive half life if you reach an decent level, so to me that's enough. they pain is usually well controlled for hours after extubation

Jesus, no wonder we have an opioid shortage

 

[Hoya11]

This may seem a little basic, but I’m a resident and am curious how most people dose their opioids. I generally don’t give any long acting opioids for cases without significant post op pain. For cases where they’ll need post op analgesia, I usually dose some long acting opioids at the start of GA because I think it lets me use less fentanyl and smoothes out the hemodynamics. So long as it’s a modest dose, I haven’t had anyone yet that fails to breath by the end of the surgery. Do others do the same? I’ve had a lot of attendings that want to wait until the end of the case and titrate to respiratory rate.

I give either dilaudid or morphine upfront before incision, sometimes even before induction while they are being connected to monitors, a decent dose like 1mg of dilaudid or 5 of morphine, especially if its a painful 2+hr case, as you said it smooths the case out. i disagree about fentanyl drips and fentanyl having a lasting effect, i much prefer dilaudid or morphine once fentanyl is >200. i have medications that act the same as the fentanyl drip and i dont have to set up a pump/bag... much simpler. in the age of eras its taboo to talk about dilaudid and morphine but its the backbone of what we do, lots of underdosed people out there in the name of eras

Throughout a case, I try to make sure that my opiate coverage matches the stimulation.. Whether its dilaudid boluses, fentanyl or remi drip, cover them with the appropriate amount of opiate to match what is going on. If possible use respiratory rate, if not use BP/HR.

Sometimes I see lots of gas and beta blocker and 50 of fentanyl for a young patient in painful belly case.. why? "ill dose it at the end" well in the mean time i do believe bad stuff happens if you just let pain ensue and cover it up

 

[B-Bone]

depends on the case. for painful cases usually 3-5 mcg/kg on induction. But usually for a skinny person like 250mcg fentanyl, then infusion of 3mcg/kg per hour.

some people like to dose 'longer' acting opioids in at the end for more post op control. however fentanyl has a long context sensitive half life if you reach an decent level, so to me that's enough. they pain is usually well controlled for hours after extubation

so for a typical 8 hour academic big spine whack, a 100 kg dude would get 2700-2900 mcg fentanyl? A two hour lap chole on the same guy would get 900-1100 mcg fentanyl? I guess that's one way to do it...

 

[deleted875186]

Opioid free baby

Does opioid free work for you? I only find it’s feasible if doing some regional. For example, for a THA under GA, I find it cruel not to dose any long acting opioids, even with giving all this miltimodal stuff. I typically try and get at least 1 mg hydromorphone on board before waking up for average opioid naive person.

Do you find doing opioid free that your PACU nurses are giving lots of opioids, or they do ok in the PACU?

 

[coffeebythelake]

i use a small dose of opioid to blunt the sympathetic response to intubation (fentanyl 1-2 mcg/kg) i don't give opioids during the maintenance phase of the case, i prefer to deepen the anesthetic or give a short acting BB. patient is not conscious so they feel no pain. near the end of the case i give about 1/2 expected opioid requirements, then when they are breathing spontaneously titrate additional opioids based on MV.

 

[deleted171991]

I grew up in an era when one gave 2 mg of dilaudid upfront. I seldom do it anymore. Most of my cases get 100 mcg of fentany (that includes spines), very few up to 250. Most of my analgesia is non-opiate. That's the future, especially in an opiate-obsessed world.

I also keep in mind that pain is easier to prevent than to treat, so I will give opiates before things get out of control, just not the "huge" doses I used to. I am much more multimodal nowadays (but that's also my group's practice model).

Some PACU nurses are still a pain in the rear and give much more opiates than I do intraop, because they just don't want to learn new things, but I find that most don't need to.

 

[coffeebythelake]

I grew up in an era when one gave 2 mg of dilaudid upfront. I seldom do it anymore. Most of my cases get 100 mcg of fentanyl, very few up to 250. Most of my analgesia is non-opiate. That's the future, especially in an opiate-obsessed world.

I also keep in mind that pain is easier to prevent than to treat, so I will give opiates before things get out of control, just not the "huge" doses I used to.

so what do u do? oral tylenol, gabapentin, carb loading, ketamine, lidocaine, regional anesthesia, +/- toradol?

 

[Urzuz]

depends on the case. for painful cases usually 3-5 mcg/kg on induction. But usually for a skinny person like 250mcg fentanyl, then infusion of 3mcg/kg per hour.

some people like to dose 'longer' acting opioids in at the end for more post op control. however fentanyl has a long context sensitive half life if you reach an decent level, so to me that's enough. they pain is usually well controlled for hours after extubation

Christ. What is the ETCO2 of your patients when you extubate them?

 

[deleted171991]

so what do u do? oral tylenol, gabapentin, carb loading, ketamine, lidocaine, regional anesthesia, +/- toradol?

Most of that, minus the gabapentin, plus magnesium.

I am comfortable both with non-opiate and opiate-based analgesic regimens. When the shortage is over, I'll just do whatever is easier for that particular patient.

 

[anbuitachi]

so for a typical 8 hour academic big spine whack, a 100 kg dude would get 2700-2900 mcg fentanyl? A two hour lap chole on the same guy would get 900-1100 mcg fentanyl? I guess that's one way to do it...

Nah I dont do it for lap choles. I dont consider them to be very painful procedures. Obviously they could be but i dont treat them as such. and a 2 hr lap chole is pretty long.

For a whole day spine case, I usually add additional stuff on top of the opioids, so i actually don't use that much fentanyl. Usually Ketamine infusion on top of fentanyl for sure, and Pre op tylenol, gaba, +/- celebrex, occasionally IV methadone in the beginning, or the surgeon injects duramorph intrathecal. Probably close to 1.5-2mg fentanyl for the case. And I usually turn it off ~1 hr or so before the end of the case. Also i dont increase fentanyl linearly based on total body weight if its mostly from fat. If its a tall buff guy 100kg sure, if it's short BMI 45, i won't be doing 3mcg/kg. Context sensitive half life of fentanyl for a 8 hr infusion is 6 hours.. so they stay pretty comfortable in PACU

Christ. What is the ETCO2 of your patients when you extubate them?

I usually stop fentanyl like a hour before extubation for long cases. Extubate in the mid 50s ETCO2.

 

[B-Bone]

For a whole day spine case, I usually add additional stuff on top of the opioids, so i actually don't use that much fentanyl. Usually Ketamine infusion on top of fentanyl for sure, and Pre op tylenol, gaba, +/- celebrex, occasionally IV methadone in the beginning, or the surgeon injects duramorph intrathecal. Probably close to 1.5-2mg fentanyl for the case.

That sounds like a great anesthetic except for the 2000 mcg fentanyl. I use a very similar approach except I give maybe 100 mcg fentanyl up front and a mg or two of dilaudid at the end of the case. I just think that much fentanyl is a waste. The only times in my career where I measured fentanyl in MILLIGRAMS was back in the day doing hearts where we kept them asleep for 2-3 days afterwards. You're a resident, right? I can't believe someone is signing off on this. Is this the norm for everyone at your program (other residents/attendings)? Just curious.

 

[anbuitachi]

That sounds like a great anesthetic except for the 2000 mcg fentanyl. I use a very similar approach except I give maybe 100 mcg fentanyl up front and a mg or two of dilaudid at the end of the case. I just think that much fentanyl is a waste. The only times in my career where I measured fentanyl in MILLIGRAMS was back in the day doing hearts where we kept them asleep for 2-3 days afterwards. You're a resident, right? I can't believe someone is signing off on this. Is this the norm for everyone at your program (other residents/attendings)? Just curious.

A waste? Why a waste? Different people have different approaches here but people definitely do not have problems with it as far as I know. I think that's one of the beauties of anesthesiology. There are often many ways to do something, you experience them all and pick the one you think works best (when there's no significant evidence against you). Now it's not everyday that we get a 100kg muscular guy getting a 8+ hr spine surgery, so we still don't see 2mg that often. But i don't think its uncommon to see long spine cases getting 1500 or so of fentanyl. Maybe not when there is a national shortage Ha! Usually though fentanyl is a very cheap drug. We only do it for what we think are painful procedures, and are long too. So a 8 hr endovascular procedure isn't going to get 2mg of fentanyl. I used to give less fentanyl in long spines, but after I switched to more fentanyl, I've noticed that patients wake up better, and are more comfortable in the PACU. Now that I think about it, these 'painful' , long cases are actually not THAT common. It's mostly big spines, and big livers with coagulopathies. Otherwise there's usually some types of regional blocks to decrease fentanyl use

 

[deleted171991]

Fentanyl is probably the biggest contributor to PONV I know.

 

[anbuitachi]

Fentanyl is probably the biggest contributor to PONV I know.

True, but haven't really been an issue, since these people are getting ondansetron, dexamethasone, and hours of propofol.

 

[Psai]

Does opioid free work for you? I only find it’s feasible if doing some regional. For example, for a THA under GA, I find it cruel not to dose any long acting opioids, even with giving all this miltimodal stuff. I typically try and get at least 1 mg hydromorphone on board before waking up for average opioid naive person.

Do you find doing opioid free that your PACU nurses are giving lots of opioids, or they do ok in the PACU?

It is pretty case and patient dependent. But if you prime the patient beforehand, run some lido, ketamine, bblocker, tylenol, decadron, toradol, it seems that some patients can get through pacu without any opioid in our opioid friendly environment. Most people do end up getting a little by pacu, maybe 1or 2 of morphine or so before being discharged.

 

[Robotic Wis-Hipple]

I’ve never bought into this idea of using “X” mcg/kg of fentanyl for specific cases, I just don’t think the dose response of any drug let alone an opioid is that set in stone. People’s opioid tolerance, pain/noxious stimuli response, implication of said noxious stimuli, surgical skill/technique, and case duration are too varied to approach it that way imo.

I’m also not one to criminalize or scapegoat fentanyl as is the current trend, I still use it, but for a longer case I’d rather front load a longer acting opioid and ride the smoother hemodynamics.

I will say I think fentanyl’s context sensitive half time makes it a poor choice for infusion in general :/

Finally, for all the opioid free advocates (I’m sure some were a bit tongue in cheek) what is your answer to the weekly addition of adjuncts to the shortage lists? Are you blocking everything? Are your PACU’s and Surgeon/Primary teams following suit and dropping all their PCA’s or opioid “rescues”? It makes little sense to me despite the knowledge of things like hyperalgesia or higher incidence of opioid conditioning and subsequent addiction being blamed on opioid based surgical anesthesia to avoid opioid analgesics only to see the PACU give 2mg of dilaudid and/or the Pt to receive opioids for 48hrs postop.

Just like everything else, the dose makes the poison.

 

[Aether2000]

We minimize opioids for every case, typically using zero for most LMA cases, and 50-100mcg fentanyl for intubation cases since we do a large number of blocks. The use of higher intraoperative opioids is associated with a higher use of opioids postoperatively (Opioid-induced hyperalgesia in patients after surgery: a systematic review and a meta-analysis. - PubMed - NCBI).

 

[dhb]

We minimize opioids for every case, typically using zero for most LMA cases, and 50-100mcg fentanyl for intubation cases since we do a large number of blocks. The use of higher intraoperative opioids is associated with a higher use of opioids postoperatively (Opioid-induced hyperalgesia in patients after surgery: a systematic review and a meta-analysis. - PubMed - NCBI).

I've never understood the fentanyl for intubation, why not give esmolol if you really need it. I almost never give opiods on induction and i don't see a big difference.

 

[Aether2000]

Good point...

 

[anbuitachi]

I've never understood the fentanyl for intubation, why not give esmolol if you really need it. I almost never give opiods on induction and i don't see a big difference.

Well the fentanyl helps with more than just the intubation, it lasts into the surgery as well. You can bolus and run esmolol infusion for the surgery if you only care about hemodynamics. But fentanyl is more for anti nociception, and i think that's more than just bp/hr. i dont know of any studies yet comparing post op outcomes of esmolol vs fentanyl though

the nociceptors continue to work during general anesthesia if you dont target it, your brain is just comatosed so you dont perceive it. the question is does that have negative effects. it's like if you have a 5 day old baby who doesn't know anything, and he's going for a procedure, and all you give is roc, i imagine that changes outcomes

 

[Wolverines83]

I've never understood the fentanyl for intubation, why not give esmolol if you really need it. I almost never give opiods on induction and i don't see a big difference.

I usually pull out 100mcg for an ETT case. Give 50ish (or whatever, based on patient) as we're coming through the OR door. Kinda chills the patient out (especially if I don't want to be giving versed to some old lady), keeps hemodynamics reasonable during induction and then I have something on board for the initial incision. Works for me. I usually don't give that other 50 until the end of the case based on respiratory rate. Patients seem comfortable enough.

That being said, I've used esmolol too and it works great on induction but........I just like to use fentanyl. How's that for honesty?

 

[parcus]

Well the fentanyl helps with more than just the intubation, it lasts into the surgery as well. You can bolus and run esmolol infusion for the surgery if you only care about hemodynamics. But fentanyl is more for anti nociception, and i think that's more than just bp/hr. i dont know of any studies yet comparing post op outcomes of esmolol vs fentanyl though

the nociceptors continue to work during general anesthesia if you dont target it, your brain is just comatosed so you dont perceive it. the question is does that have negative effects. it's like if you have a 5 day old baby who doesn't know anything, and he's going for a procedure, and all you give is roc, i imagine that changes outcomes

Or maybe it just causes some downregulation of pain receptors while the patient is unconscious, hence some studies suggesting opioid hyperalgesia? I don't believe the propofol only induction would work well unless the doses were verythigh, the risk of running into a difficult airway and using more force resulting in awakening would be too high. That said, I wonder how people came up with the 2mg/kg of propofol and 3 mcg/kg of fentanyl, plenty of people seem to be using a lot less than that (even adjusting for age, etc) with success. It doesn't suppress reflexes all too well either, patients inevitably cough once tube is between vocal cords. I wonder if it was designed for suppressing reaction to laryngoscopy for intubations with no NMB.

 

[Psai]

I usually pull out 100mcg for an ETT case. Give 50ish (or whatever, based on patient) as we're coming through the OR door. Kinda chills the patient out (especially if I don't want to be giving versed to some old lady), keeps hemodynamics reasonable during induction and then I have something on board for the initial incision. Works for me. I usually don't give that other 50 until the end of the case based on respiratory rate. Patients seem comfortable enough.

That being said, I've used esmolol too and it works great on induction but........I just like to use fentanyl. How's that for honesty?

I am very similar except for big flaps and things like that where I take out extra fent. I take out a 250 just in case but usually use maybe 100 or so for most cases if I'm deciding the dose.

 

[anbuitachi]

Or maybe it just causes some downregulation of pain receptors while the patient is unconscious, hence some studies suggesting opioid hyperalgesia? I don't believe the propofol only induction would work well unless the doses were verythigh, the risk of running into a difficult airway and using more force resulting in awakening would be too high. That said, I wonder how people came up with the 2mg/kg of propofol and 3 mcg/kg of fentanyl, plenty of people seem to be using a lot less than that (even adjusting for age, etc) with success. It doesn't suppress reflexes all too well either, patients inevitably coughs once tube is between vocal cords. I wonder if it was designed for suppressing reaction to laryngoscopy for intubations with no NMB.

I think 3-5mcg/kg of fentanyl does a pretty good job at blunting reflexes. I think the issue is people often dont wait the 3-5 minutes after giving 3-5mcg/kg for the fentanyl to peak. Of course there are those outliers who will cough regardless

 

[coffeebythelake]

Most of that, minus the gabapentin, plus magnesium.

I am comfortable both with non-opiate and opiate-based analgesic regimens. When the shortage is over, I'll just do whatever is easier for that particular patient.

How much Mg do u use?

 

[DeadSpace]

I agree with the OP. Dosing with opioids seems to vary greatly depending on which attending I'm working with. I learned to do 50 mcg of Fent on induction and 50 mcg right before incision (for most people). Then yesterday I got accused of being cruel to the lap chole patient and a different attending pushed 250 mcg of Fent. Then you throw in the attending who is totally opioid-free and you have me just giving up on ever being right.

 

[deleted171991]

How much Mg do u use?

Typically about 1 g/hour.

 

[anbuitachi]

Typically about 1 mg/hour.

how about bolusing

 

[deleted171991]

how about bolusing

It's probably fine, as long as you don't do it too fast and watch the blood pressure, although I have never done it faster than 1 g/10 min.

 

[nimbus]

Then yesterday I got accused of being cruel to the lap chole patient and a different attending pushed 250 mcg of Fent.

I would suggest not doing this on your first PP lap chole

 

[zizzer]

My overall goal is to prevent nociceptor sensitization all along the pain pathway to avoid the wind-up phenonomon. I will use opioids to do this, but only to the extent that I am unable to use nonopioid alternatives. Obviously, regional anesthesia is great here, but even so it does not prevent peripheral nociceptor sensitization peripheral to the block, so systemic pharmacologic analgesia is still helpful. Here I just try to focus on all of the receptors that transmit pain and try to block them. I also try decreasing acute inflammation to decrease peripheral inflammation.

I usually use pre-operative acetaminophen 1g, and gabapentin (300mg if naive, 600mg if chronic user). I avoid oral/transdermal clonidine usually because I have enough intraoperative agents causing hypotension, but they would probably be good for healthier patients undergoing less risky surgeries. Dexmedetomidine might be a useful alternative as an alpha-2 agonist here, but cost is prohibitive. I use dexamethasone as an antiinflammatory agent: 8-10mg early on if I don't have other concerns about it. Pre-operative celecoxib is good if the patient's renal function is good, but make sure your surgeon isn't going to think it has antiplatelet action or something. I use lidocaine on induction and infusion for painful surgeries. Regarding NMDA antagonism, I'll use a ketamine loading dose followed by 30 minute interval boluses, N2O when possible, and Mg as off-pump boluses (just not wide-open to prevent hypotension). 15mg of ketorolac during closing when surgery is ok with it. After a good chunk of these interventions. It's also important to note that using some of these into the recovery phase is useful to as sensitization can happen post-operatively too.

After all or some of these, I'll use opioids to cover any intraoperative pain transmission that I feel is needed. If I have a good regional block, I won't use intraoperative opioids, but otherwise I'll usually use a modest dose of fentanyl on induction (<=100mcg) with intermittent boluses. For painful long cases I might do an infusion (not fentanyl because of context-sensitive half-life effect). I do use modest doses of longer acting opioids towards the end and/or postoperatively (morphine or hydromorphone).

For what it's worth, I'm a CA-1 and so much of this is based on reading with limited experience. I'm not an authority by any means, and often I don't get to do all this stuff because my attending has other preferences.

 

[dhb]

My overall goal is to prevent nociceptor sensitization all along the pain pathway to avoid the wind-up phenonomon. I will use opioids to do this, but only to the extent that I am unable to use nonopioid alternatives. Obviously, regional anesthesia is great here, but even so it does not prevent peripheral nociceptor sensitization peripheral to the block, so systemic pharmacologic analgesia is still helpful. Here I just try to focus on all of the receptors that transmit pain and try to block them. I also try decreasing acute inflammation to decrease peripheral inflammation.

I usually use pre-operative acetaminophen 1g, and gabapentin (300mg if naive, 600mg if chronic user). I avoid oral/transdermal clonidine usually because I have enough intraoperative agents causing hypotension, but they would probably be good for healthier patients undergoing less risky surgeries. Dexmedetomidine might be a useful alternative as an alpha-2 agonist here, but cost is prohibitive. I use dexamethasone as an antiinflammatory agent: 8-10mg early on if I don't have other concerns about it. Pre-operative celecoxib is good if the patient's renal function is good, but make sure your surgeon isn't going to think it has antiplatelet action or something. I use lidocaine on induction and infusion for painful surgeries. Regarding NMDA antagonism, I'll use a ketamine loading dose followed by 30 minute interval boluses, N2O when possible, and Mg as off-pump boluses (just not wide-open to prevent hypotension). 15mg of ketorolac during closing when surgery is ok with it. After a good chunk of these interventions. It's also important to note that using some of these into the recovery phase is useful to as sensitization can happen post-operatively too.

After all or some of these, I'll use opioids to cover any intraoperative pain transmission that I feel is needed. If I have a good regional block, I won't use intraoperative opioids, but otherwise I'll usually use a modest dose of fentanyl on induction (<=100mcg) with intermittent boluses. For painful long cases I might do an infusion (not fentanyl because of context-sensitive half-life effect). I do use modest doses of longer acting opioids towards the end and/or postoperatively (morphine or hydromorphone).

For what it's worth, I'm a CA-1 and so much of this is based on reading with limited experience. I'm not an authority by any means, and often I don't get to do all this stuff because my attending has other preferences.

Too much work!

I don't believe in all the wind up hypersensivity etc etc (see other thread about bad studies).

Maybe i've said this before but i simply think that if you saturate the patient opioid receptor per-operatively (with whatever agent) you are going to need more opioids and in larger doses post-operatively to get an effective response.
If you don't give any per-operatively then the effect of the morphine you give in PACU will be much more pronounced. Typically a laparotomy with a TAP block will receive 2-4mg of morphine in PACU.

 

[Ronin786]

How much Mg do u use?

50 mg/kg is a good number. There's a good review in Anesthesiology (Perioperative Systemic Magnesium to Minimize Postoperative Pain:A Meta-analysis of Randomized Controlled Trials | Anesthesiology | ASA Publications)

In all the studies they looked at, they didn't find any side effects including hypotension, arrhythmia or bradycardia. Only thing to keep in mind is it does potentiate NMB, but use it a few times and the train tracking of vitals is quite impressive IMO.