Low-dose ketamine and emergence

[Gator05]

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To the Jedi of anesthesia,

I've been trying some new things out for my run-of-the-mill cases. One of our newer attendings introduced PFK anesthesia, and as a corollary, expanded the use of low-dose (less than 50mg/case) ketamine.

As part of my new induction regimen, 1-2mg versed, ~25mg ketamine, 150-200mg propofol, sux/vec and tube/LMA. Maint with Sevo/Propofol or Sevo/N2O. Titrate narcotic based on hemodynamics (yes, bad idea, but I'm human), expected hourly requirement, etc.

End of the case is where things get interesting. We have PSVPro on our machines so it's rare not to have the patient spontaneously breathing throughout the remainder of the case. Agents off; by end of dressing <0.05 agent, N2O <10% ET and if propofol off >15-20 minutes (after running 50-100 mcg/kg/min for the case as an adjunct to spare inhalational).

Patient with a smile on their face, breathing regularyly and comfortably with appropriate gag to suction, but won't wake up. Pull tube while patient deep, patient rock stable hemodynamic/resp, to PACU. After ~20 minutes in PACU, patient opens their eyes, smiles and asks for food.

Any problem with extubating with only criterion of regular resps, oxygenating/ventilating well with appropriate gag? Anyone else using low-dose ketamine? Appreciate any tips.

 

[Noyac]

To the Jedi of anesthesia,

I've been trying some new things out for my run-of-the-mill cases. One of our newer attendings introduced PFK anesthesia, and as a corollary, expanded the use of low-dose (less than 50mg/case) ketamine.

As part of my new induction regimen, 1-2mg versed, ~25mg ketamine, 150-200mg propofol, sux/vec and tube/LMA. Maint with Sevo/Propofol or Sevo/N2O. Titrate narcotic based on hemodynamics (yes, bad idea, but I'm human), expected hourly requirement, etc.

End of the case is where things get interesting. We have PSVPro on our machines so it's rare not to have the patient spontaneously breathing throughout the remainder of the case. Agents off; by end of dressing <0.05 agent, N2O <10% ET and if propofol off >15-20 minutes (after running 50-100 mcg/kg/min for the case as an adjunct to spare inhalational).

Patient with a smile on their face, breathing regularyly and comfortably with appropriate gag to suction, but won't wake up. Pull tube while patient deep, patient rock stable hemodynamic/resp, to PACU. After ~20 minutes in PACU, patient opens their eyes, smiles and asks for food.

Any problem with extubating with only criterion of regular resps, oxygenating/ventilating well with appropriate gag? Anyone else using low-dose ketamine? Appreciate any tips.

It all sounds pretty routine for me. I don't know what more you want from them when waking them up. Mine do respond quite a bit earlier though. They are usually asking for something to eat b/4 leaving the room. I have them extubated while the skin sutures are going in. They can move themselves to the stretcher about 1/2 the time. the other 1/2 we move them b/c they just don't move fast enough for me. sometimes they go straight to a recliner in the OR and directly to phase II.

 

[Planktonmd]

To the Jedi of anesthesia,

I've been trying some new things out for my run-of-the-mill cases. One of our newer attendings introduced PFK anesthesia, and as a corollary, expanded the use of low-dose (less than 50mg/case) ketamine.

As part of my new induction regimen, 1-2mg versed, ~25mg ketamine, 150-200mg propofol, sux/vec and tube/LMA. Maint with Sevo/Propofol or Sevo/N2O. Titrate narcotic based on hemodynamics (yes, bad idea, but I'm human), expected hourly requirement, etc.

End of the case is where things get interesting. We have PSVPro on our machines so it's rare not to have the patient spontaneously breathing throughout the remainder of the case. Agents off; by end of dressing <0.05 agent, N2O <10% ET and if propofol off >15-20 minutes (after running 50-100 mcg/kg/min for the case as an adjunct to spare inhalational).

Patient with a smile on their face, breathing regularyly and comfortably with appropriate gag to suction, but won't wake up. Pull tube while patient deep, patient rock stable hemodynamic/resp, to PACU. After ~20 minutes in PACU, patient opens their eyes, smiles and asks for food.

Any problem with extubating with only criterion of regular resps, oxygenating/ventilating well with appropriate gag? Anyone else using low-dose ketamine? Appreciate any tips.

I guess your question is if it's ok to take the tube out before the patient pulls it out himself, and the answer is yes! (if you know what you are doing).
I know in residency they teach all these things about following command and lifting the head and all kinds of great things which are perfectly fine but might not be very practical in some situations.
On the other hand I think you are using way too many things: (Benzo + Narcotic + Propofol + Ketamine + Muscle realxant + Vapor + N2O), I think you can do exactly what you are trying to do with less polypharmacy (again if you know what you are doing), but that's just a personal opinion and since you are a resident it's actually great to try everything and play a little, eventually you will develop your own style.

 

[ZA_Gasman]

I quite like the idea of a little Ketamine. Especially in the light of its action in modulating pain pathways via the NMDA receptor. If it spares you some opioids, then why not? I've also taken to giving 2g Magnesium sulphate in the 1st bag of fluid (peri-induction) unless contra-indicated. I find that it has a good opiate sparing effect also (?NMDA receptor block?).

Have just read the original post more carefully - do I understand correctly Gator, that you run a Propofol infusion in addition to Nitrous AND gas? I appreciate that it may give you a more stable anaesthetic, but the cost implications must be prohibitive, especially if you're worried about Compound A and run Fresh gas >1.5L/min with Sevoflurane. We certainly don't have a departmental budget for such extravagant dopes.

Not saying I wouldn't like to try it though. I'll pass on the nitrous oxide though...

 

[sevoflurane]

Ketafol is great. At my institution we use 500mg of propofol into 100mg of ketamine at about 50-100mcg/kg/min. (after 100 or so of fentanyl before induction). Usually use low flow gases with some versed upfront +/- diazepam in my fluids just in case of delerious emergence. Ketamine has a long half-life compared to propofol so i turn off my pseudo-TIVA concoction about 15 minutes before the case ends (depending on the case). I can easily get rid of my agent because at low flows I likely have not saturated much fat (takes about an hour to get an end tidal of 0.7 iso and I never let it get above 0.8)
Propofol wears off quickly and ketamine is not much of a respiratory depressant, so getting them to wake up is almost never an issue. In my experience, I've yet to find a single person complaining of PONV.
All that said and done... I still like my patients cooperating before pulling a tube. Never had to re-intubate someone... in the PACU. I don't think I'd like it if I had to re-intubate my patient shortly after pulling the tube.- probably a newbee thing.

 

[sevoflurane]

I quite like the idea of a little Ketamine. Especially in the light of its action in modulating pain pathways via the NMDA receptor. If it spares you some opioids, then why not? I've also taken to giving 2g Magnesium sulphate in the 1st bag of fluid (peri-induction) unless contra-indicated. I find that it has a good opiate sparing effect also (?NMDA receptor block?).

Have just read the original post more carefully - do I understand correctly Gator, that you run a Propofol infusion in addition to Nitrous AND gas? I appreciate that it may give you a more stable anaesthetic, but the cost implications must be prohibitive, especially if you're worried about Compound A and run Fresh gas >1.5L/min with Sevoflurane. We certainly don't have a departmental budget for such extravagant dopes.

Not saying I wouldn't like to try it though. I'll pass on the nitrous oxide though...

Funny you say that... I have a friend who also likes to add a bit of mag to the mix. He also favors .1mg of clonidine into his fluids for selected cases as well as for breakthrough pain in opiod tolerant patients.

 

[Gator05]

Appreciate the points.

Point about the poly-pharmacy is well-taken. Usually, I use 1-2 versed, then ketamine. Then, maint with either propofol/nitrous, propofol/inhalational agent, or nitrous/agent. Most of these cases are >2 hours, so I figure the initial versed is at least waning if not off.

I've never mastered the triple-threat.

Does the Mg add anything if you're already using ketamine?

 

[ZA_Gasman]

Does the Mg add anything if you're already using ketamine?

Not sure. Will have to do some research. As far as I'm aware they act on different NDMA receptors. Mg also offers other benefits though, neuroprotection, ventricular stabilisation etc. I know a guy here who uses 1g of Mg intra-articularly after knee 'scopes and says he gets excellent analgesia.

I like it because it is cheap and has really minimal s/e apart from that pesky hypotension thing😛

Clonidine is also nice, some of the older guys around here use it as a premed - really whacks the pt though. The same guy mentioned above is also advocating running Dexmedetomidine intra and post op as a secondary analgesic - bit dodgy though as only licenced here for ICU sedation post Cardiac surgery - but i guess off-label use is the only way that the indications get expanded. ..

 

[sevoflurane]

Not sure. Will have to do some research. As far as I'm aware they act on different NDMA receptors. Mg also offers other benefits though, neuroprotection, ventricular stabilisation etc. I know a guy here who uses 1g of Mg intra-articularly after knee 'scopes and says he gets excellent analgesia.

I like it because it is cheap and has really minimal s/e apart from that pesky hypotension thing😛

Clonidine is also nice, some of the older guys around here use it as a premed - really whacks the pt though. The same guy mentioned above is also advocating running Dexmedetomidine intra and post op as a secondary analgesic - bit dodgy though as only licenced here for ICU sedation post Cardiac surgery - but i guess off-label use is the only way that the indications get expanded. ..

Today I was told..."dexmedatomidine 4mg = $2000" Sounds a bit pricy for everyday use.

 

[nimbus]

Today I was told..."dexmedatomidine 4mg = $2000" Sounds a bit pricy for everyday use.

You can get 200 mcg vials for about $50 plus or minus depending on your local contracts. Enough for most 2-3 hr cases.

 

[nimbus]

Patient with a smile on their face, breathing regularyly and comfortably with appropriate gag to suction, but won't wake up. Pull tube while patient deep, patient rock stable hemodynamic/resp, to PACU. After ~20 minutes in PACU, patient opens their eyes, smiles and asks for food.

Any problem with extubating with only criterion of regular resps, oxygenating/ventilating well with appropriate gag? Anyone else using low-dose ketamine? Appreciate any tips.

This reflects my experience too. Sometimes they sleep awhile after the procedure is finished, then wake up suddenly without lingering drowsiness/nausea/etc and in a good mood. For most cases, I just take them to PACU with the ETT or LMA in if they are still very sleepy. Why take a chance?

 

[Planktonmd]

This reflects my experience too. Sometimes they sleep awhile after the procedure is finished, then wake up suddenly without lingering drowsiness/nausea/etc and in a good mood. For most cases, I just take them to PACU with the ETT or LMA in if they are still very sleepy. Why take a chance?

Just curious: If you take them intubated to PACU who extubates them?

 

[ZA_Gasman]

Today I was told..."dexmedatomidine 4mg = $2000" Sounds a bit pricy for everyday use.

Yeah. Sorry forgot to mention he is in private practice - almost unlimited source of funds here (at the moment anyway) compared to my state sector job where Dex is certainly beyond the scope of routine use.

 

[nimbus]

Just curious: If you take them intubated to PACU who extubates them?

Pacu nurses. They do it all the time here. Makes for very short turnovers, even after big cases.