Ketafol recipes and experience

[fakin' the funk]

Wanted to see what the various ketafol fans out there are doing for their clinical situations they use it in, concentrations, doses, and experiences. (That oddly sounds like an erowid question, but I'm asking about clinical use)

It's very hard to find info on context sensitive half times for ketamine infusions. I think given that it's very lipophilic, short duration, and duration of boluses are determined by redistribution, i.e., like propofol, it's reasonable to run the two together and essentially treat ketamine's kinetics like propofol's.

In a few old posts, members have said they dilute ketamine to 1 mg/ml in their propofol bottle then just run the prop. If you are running propofol up to, say, 100 mcg/kg/min putting your ketamine at 10 mcg/kg/min (i.e. 0.6mg/kg/h), are you seeing a lot of delayed wakeups, delirium, or other untoward side effects upon wakeup? How long before case end do you shut it off? Any situations where you'd use more or less, or run them separately?

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[Ignatius J]

Wanted to see what the various ketafol fans out there are doing for their clinical situations they use it in, concentrations, doses, and experiences. (That oddly sounds like an erowid question, but I'm asking about clinical use)

It's very hard to find info on context sensitive half times for ketamine infusions. I think given that it's very lipophilic, short duration, and duration of boluses are determined by redistribution, i.e., like propofol, it's reasonable to run the two together and essentially treat ketamine's kinetics like propofol's.

In a few old posts, members have said they dilute ketamine to 1 mg/ml in their propofol bottle then just run the prop. If you are running propofol up to, say, 100 mcg/kg/min putting your ketamine at 10 mcg/kg/min (i.e. 0.6mg/kg/h), are you seeing a lot of delayed wakeups, delirium, or other untoward side effects upon wakeup? How long before case end do you shut it off? Any situations where you'd use more or less, or run them separately?

1cc of 50mg/ml Ketamine in a stick of Propofol. Run it based on the Propofol.

I liked it for endoscopy. Never had issues with emergences.

What type of cases are you talking about?

 

[pgg]

These days I prefer to pick a total dose of ketamine for a patient, usually 0.5 mg/kg or less, give it early in the infusion (or as an outright bolus prior to procedure start), then no more ketamine.

So if I decide that I'm going to do a D&C in a 70 kg woman, I might add 30 mg of ketamine to 10 mL of propofol, put that syringe on the pump first, run it in at 200 mcg/kg/min starting when we roll in the door, then 7 or 8 minutes later, by the time she's positioned and getting prepped, that syringe is done and I just replace it with plain propofol. Then no more ketamine. This works really well for other short cases that aren't real painful afterwards, like most endoscopy.

I used to put 1 mg/mL in the propofol and just run it for however long the case went, but I find I get more predictable results if I pick a dose of ketamine up front and then keep them asleep with propofol.


Someone at my current hospital presented a delayed emergence M&M a while ago after doing a long case under a ketafol TIVA. Total dose of ketamine was something ridiculous like 400 mg, but they just kept putting syringes with 2 mg/mL on the pump ...

 

[deleted171991]

If one runs propofol at p mcg/kg/min, and the same syringe contains k mg of ketamine per ml of propofol, one is also giving ketamine at 0.1*p*k mcg/kg/min = 0.006*p*k mg/kg/h.

For example, if the propofol rate is 200, and the ketamine concentration is 2 mg per ml of propofol, the ketamine rate is 2.4 mg/kg/h. For long cases... ouch! The best way to avoid delayed emergence seems to be to just keep ketamine at 1 mg (or less) per ml of propofol.

I use ketafol at 1 mg/ml exclusively in some BMI 50+ endoscopy patients with bad airways. Otherwise, not worth it, in my book (too much headache with wasting the ketamine).

 

[criticalelement]

If one runs propofol at p mcg/kg/min, and the same syringe contains k mg of ketamine per ml of propofol, one is also giving ketamine at 0.1*p*k mcg/kg/min = 0.006*p*k mg/kg/h.
).

what am i in math class.? geez. If i have to go through this i will forego the darn drug. WHich i do. Have NEVER used ketamine. And i recommend noone use it too

 

[BLADEMDA]

what am i in math class.? geez. If i have to go through this i will forego the darn drug. WHich i do. Have NEVER used ketamine. And i recommend noone use it too

I disagree completely with the above post. Ketamine is a great drug and is vastly underutilized by most Anesthesiologists. I encourage everyone to use Ketamine (low dose) for many situations:

1. Low EF- great induction agent with propofol (0.5 mg/kg propofol and 0.5 mg/kg ketamine)
2. Great sedative for ASA4 cases like EGD ( ketamine 20-30 mg IV bolus then mix the ketamine in with the propofol at 1 mg/ml)
3. Great for Chronic Pain Patients- Higher doses can be used here up to 200-250 mg over a 2 hour period
4. Neuromonitoring cases- Great to add the ketamine to the propofol
5. Awake Intubation- Glyco, Ketamine (30-50 mg), Precedex and Versed go a long way when given in COMBINATION/Synergism
6. Elderly Patients with Dementia- Regional with Ketafol may decrease morbidity and mortality


Some studies suggest Ketamine 0.3-0.5 mg/kg bolus followed by an infusion of 1-10 ug/kg/min as Ketamine has a redistribution half life of 10-15 minutes.
I usually just give bolus and mix the ketamine with the propofol at 1mg/ml of ketamine but the purists may want to know that some studies suggest infusions of 2-8 ug/kg/min of ketamine after the bolus.

My personal limit of Ketamine is in the 150-200 mg range over 2 hours (non Chronic pain patients). In addition., small bolus doses don't typically cause HTN or tachycardia even in critically ill patients or those with low EF (I've seen a brief hypertensive response only once after a 30 mg IV bolus of Ketamine out of several thousand patients and that was possibly because I gave the Ketamine BEFORE the Propofol)

Opioid Naive patients don't need more than 2-6 ug/kg/min of Ketamine while Opioid users (Chronic pain) may benefit from a higher infusion rate of 6-10 ug/kg/min. Personally, I stick with LOW DOSE ketamine in order to avoid any side-effects from the drug.

 

[BLADEMDA]

http://www.ncbi.nlm.nih.gov/pubmed/25231491


http://www.ncbi.nlm.nih.gov/pubmed/24848384


http://www.ncbi.nlm.nih.gov/pubmed/24635528


http://www.ncbi.nlm.nih.gov/pubmed/20693876

 

[Noyac]

what am i in math class.? geez. If i have to go through this i will forego the darn drug. WHich i do. Have NEVER used ketamine. And i recommend noone use it too

Really?
Your pulling our legs, right?
Can I suggest a new rule, whenever anyone makes a recommendation like the one above they must also give a reason. Otherwise, it's just wind.

 

[sleepallday]

Is anyone using or has used ketamine as the sole anesthetic for GA? If so, are you securing the airway? (i apologize in advance if I'm taking this thread too far off topic)

 

[criticalelement]

Really?
Your pulling our legs, right?

I am pulling your legs. I use ketamine all the time. Love the drug

 

[sevoflurane]

Is anyone using or has used ketamine as the sole anesthetic for GA? If so, are you securing the airway? (i apologize in advance if I'm taking this thread too far off topic)

Yes. IM ketamine for an eye exam for a pedi patient after an MVC and airbag deployment.

Worked exceptionally well.

 

[BLADEMDA]

Ketamine may also decrease the inflammatory response to surgery which is another reason to use it.

http://www.ncbi.nlm.nih.gov/pubmed/22826531

 

[sevoflurane]

Is anyone using or has used ketamine as the sole anesthetic for GA? If so, are you securing the airway? (i apologize in advance if I'm taking this thread too far off topic)

Did not secure the AW, but was ready to place an lma. Pedi patient kept spontaneous vent. and all he needed was NC. They used one of those clockwork orange eye opener thingy's... Ketamine is da bomb.

 

[BLADEMDA]

Is anyone using or has used ketamine as the sole anesthetic for GA? If so, are you securing the airway? (i apologize in advance if I'm taking this thread too far off topic)

Ketamine would be a poor choice as the sole anesthetic agent for a GA unless you were anesthetizing your ex-wife's lawyer.

Ketamine is best used along with other agents like Propofol, Precedex, Remifentanyl, Sufenta, Inhalational agents, etc. in order to minimize side-effects from giving high doses of the drug.

 

[BLADEMDA]

Ketamine is a NASTY drug when used as the sole anesthetic; here is a comment from the early 1970s:

To the Editor: Emergence from ketamine anaesthesia in the postoperative period may be associated with visual, auditory, proprioceptive and confusional illusions which may progress to delirium, t Droperidol 2 and benzodiazepines I can reduce or mitigate these reactions but there is no uniform agreement concerning their effectiveness. In this letter we present the results of a study, conducted to ascertain the effect of music on the emergence phenomena after ketamine anaesthesia. Eighty ASA-I patients aged 10-25 yr undergoing minor surgical procedures of less than 45 min under ketamine anaesthesia were randomly divided into two groups of 40. All the patients were given intravenous diazepam in the dose ofO.2 mg. kg-'. Headphones were applied to all the patients and music of the patient's choice was switched on in the study group five minutes before giving ketamine 2 mg.kg-I iv, while the control group received no music. Supplemental doses of ketamine I mg.kg -~ were given every ten minutes whenever required. Headphones were removed two hours after the last dose of ketamine. Two days after surgery the patients answered a questionnaire based on that of Garfield et al. 3 The incidence of dreams in the study group (23/40) was higher (P < 0.05) than that in the control group (12). However, none of the patients in the study group had unpleasant dreams with horror, while ten of the control group reported unpleasant experiences. More patients in the study group (32/40) opted to have a similar anaesthetic than in the control group (10/40) (P < 0.01) while ten patients in the control group and none in the study group refused to have a similar anaesthetic in future (P < 0.01 ). Thus although the addition of music with ketamine anaesthesia increases the incidence of emergence phenomena the quality of wakening is pleasant and more acceptable to patients. The reasons for the differences are not known but may be attributed to the modulation of sensory experiences by music

 

[sleepallday]

Did not secure the AW, but was ready to place an lma. Pedi patient kept spontaneous vent. and all he needed was NC. They used one of those clockwork orange eye opener thingy's... Ketamine is da bomb.

haha, nice. What dosage did you use? Bolus?

 

[sleepallday]

Ketamine would be a poor choice as the sole anesthetic agent for a GA unless you were anesthetizing your ex-wife's lawyer.

Ketamine is best used along with other agents like Propofol, Precedex, Remifentanyl, Sufenta, Inhalational agents, etc. in order to minimize side-effects from giving high doses of the drug.

I am aware. The reason I'm asking is that I may possibly go on a surgical mission later this year. And it seems that anesthesiologists only use ketamine and then let the kids breath spontaneously.

 

[sevoflurane]

haha, nice. What dosage did you use? Bolus?

This was years ago, but I want to say something like 8-10 mg/kg. You get surgical anesthesia for some time at those levels. This kid had pulled out his IV like 4-5 different times and was inconsolable. You could hear his screaming all over the ED... until I darted him. Quited right down and the Eye exam was done in 5 minutes. Optho...was like...

Worked like a charm.

 

[sevoflurane]

I am aware. The reason I'm asking is that I may possibly go on a surgical mission later this year. And it seems that anesthesiologists only use ketamine and then let the kids breath spontaneously.

Ketamine is huge on many mission trips. Cheap and extremely effective.

Lot's of regional on those trips as well. Place spinal... run to room next door and place another spinal... then take care of 2 patients at the same time. This set up happens all the time.

 

[sleepallday]

This was years ago, but I want to say something like 8-10 mg/kg. You get surgical anesthesia for some time at those levels. This kid had pulled out his IV like 4-5 different times and was inconsolable. You could hear his screaming all over the ED... until I darted him. Quited right down and the Eye exam was done in 5 minutes. Optho...was like...

Worked like a charm.

Ketamine is huge on many mission trips. Cheap and extremely effective.

Lot's of regional on those trips as well. Place spinal... run to room next door and place another spinal... then take care of 2 patients at the same time. This set up happens all the time.

Thanks for the tips. Gotta say, its pretty sweet to have a forum like this to get some solid info.

 

[sevoflurane]

I think there is a lot to be learned on some of these mission trips as many times it forces you to step outside of your comfort zone.
I hope you get the chance to go.

 

[BLADEMDA]

I am aware. The reason I'm asking is that I may possibly go on a surgical mission later this year. And it seems that anesthesiologists only use ketamine and then let the kids breath spontaneously.

Ketamine 2 mg/kg Iv for induction then ketamine 0.5-1 mg/kg IV every 10 minutes for maint. or an IV infusion of Ketamine 20-80 ug/kg/mim



Adult patients induced with ketamine augmented with IV diazepam may be maintained on ketamine given by slow microdrip infusion technique at a dose of 0.1 to 0.5 mg/min, augmented with diazepam 2 to 5 mg administered IV as needed. In many cases, 20 mg or less of IV diazepam total for combined induction and maintenance will suffice. However, slightly more diazepam may be required depending on the nature and duration of the operation, physical status of the patient, and other factors. The incidence of psychological manifestations during emergence, particularly dream-like observations and emergence delirium, may be reduced by this maintenance dosage program.

 

[BLADEMDA]

Ketamine Infusions:


http://rsdfoundation.org/en/Ketamine_Treatment.html

 

[epidural man]

I Agree with PGG -

Keep the total dose low. If running a prop-amine mix for long cases, stop putting ketamine in after about 100-150mg of ketamine.

Thanks BLADEMDA for the articles. People always show ketamine articles, but they never quote this one (attached). This article is phenomenal. What is so amazing is the people with ketamine IV had better pain scores and wound hyperalgesia 6 MONTHS after surgery. What you do today in the OR helps patients 6 months later. That is rather phenomenal. They did a bolus of 0.5mg/kg on induction, then an infusion of 0.25mg/kg/hr. (Well, in one arm - they had 5 arms). Check it out.

Interestingly, I stopped using it when in Afghanistan. First of all, for some reason, those people have no pain (I mostly took care of the natives). Seriously. It is very strange. Secondly, I stopped using it, and the CRNA I was with kept using it. The nurse that recovered these patients said my patients recovered MUCH quicker and smoothly.

There is a downside to ketamine - so hence the reason to keep the drug total dose low - and probably turn off a good amount of time before the end of the case.

Als0, I used to want a smooth wake up. Now I just want a very fast wakeup. The patient reaching to pull out his ET tube is a great thing. My greatest acheivement is if I can get the patient to move themself over to the gurney. "Hey buddy. Move yourself over to this bed!" I love it when that happens.

 

[G-Man82]

I actually resorted to Ketamine as a sedative in the MICU just yesterday. I'm rotating through electively and inherited a patient with severe ARDS and MODS on VV ECMO, CVVHD and pressors. Cause is likely infectious with associated pulmonary and diffuse alveolar hemorrhage. I'm guessing because of his increased Vd, he was requiring 600 mcg/hr of fentanyl and 15 mg per hour of lorazepam (a MICU favorite). Astronomically high in my opinion. But he was too agitated still and there were problems with the ECMO. Flows were inconsistent and low. We ruled out problems with the cannulas and fluid balance. But he was fighting the ventilator (conventional lung protective settings) and our thinking was that the elevated intrathoracic pressures were impeding flows. Couldn't do propofol bc of his triglycerides from its last use. But we wanted to paralyze but needed to make him a little more sedated and less responsive before hitting him with atracurium. I suggested ketamine, managed to get pharmacy and nursing on board, gave him a bolus of 1 mg/kg and started an infusion at 0.5 mg/kg/hr (now at 1) and he did really well.

Hemodynamics stabilized, flows stabilized, lungs look a little better since we're not pouring fluid into him. I don't suggest it as a first line agent in the ICU but as a rescue agent in super tolerant patients or patients on mechanical support, I like it so far.

 

[BLADEMDA]

Acta Anaesthesiol Scand. 2007 Oct;51(9):1166-71. Epub 2007 Aug 20.
Bowel function after bowel surgery: morphine with ketamine or placebo; a randomized controlled trial pilot study.
McKay WP1, Donais P.
Author information

Abstract
BACKGROUND:
Morphine decreases gut peristalsis, and ketamine decreases morphine use after surgery, and does not slow peristalsis. Thus, the combination should result in faster return of bowel function after surgery than morphine alone.

METHOD:
A double-blind randomized controlled trial of saline vs. ketamine with intravenous patient-controlled-analgesia morphine for post-operative pain control was conducted on 42 patients having bowel resection. Bowel function was assessed by auscultation, time to passage of flatus and stool, and time to first retained oral intake; pain by visual analog scale. Time to return of all four measures of bowel function was the primary outcome.

RESULTS:
Despite a ketamine dose that in other studies had decreased morphine use without side-effects, there was no difference in bowel function, pain control, or morphine use between the two groups. Ketamine resulted in hallucinations in six out of 19 patients, with none in the placebo group (P =0.018).

CONCLUSION:
Low-dose ketamine was not efficacious for hastening return of bowel function, or for decreasing post-operative pain after surgery for bowel resection. It resulted in hallucinations in some patients. Those reporting hallucinations all wished to remain in the study.

 

[BLADEMDA]

Preoperative low-dose ketamine has no preemptive analgesic effect in opioid-naive patients undergoing colon surgery


Beatriz Nistal-Nuno, MD*, E Freire Vila, FJ Castro Seoane, A de la Iglesia Lopez, MA Camba Rodriguez

*Corresponding author: Beatriz Nistal-Nuno, MD
Department of Anesthesiology, Complexo Hospitalario Universitario A Coruna (CHUAC), A Coruna, Spain

F1000Posters 2014, 5: 848 (poster) [English]

Poster [618.14 KB]

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Presented at:
Euroanaesthesia 2014, 31 May - 3 Jun 2014, 14AP9-1

Affiliated Society:
European Society of Anaesthesiology

Background / Purpose:
The analgesic properties of ketamine are related to its actions as a non-competitive N-methyl-D-aspartate receptor antagonist; these receptors present an excitatory function on pain transmission and this binding seems to prevent or reverse its central sensitization. In literature, the use of this anesthetic for preemptive analgesia in the management of postoperative pain is controversial. The objective of this study was to determine whether preoperative low-dose-ketamine reduces postoperative pain and morphine consumption in adults undergoing colon surgery.
Main conclusion:
Preoperative low-dose-ketamine did not have a preemptive analgesic effect; nor was it effective as an adjuvant to decrease opioid requirement or postoperative pain in patients receiving intravenous analgesia with morphine after colon surgery.

 

[deleted162650]

Ketofol has become my MAC drug of choice for just about all sedation cases that don't also have some form of regional covering the surgical site. My recipe is to put 200mg ketamine and 200mg Lido(10cc of 2%) into a 100mL bottle of propofol. Small bolus and then start the infusion. I've found you can run the infusion 25-50mcg/kg/min less than if you were just using straight prop which means less apnea and also less of that disinhibition squirming you see with straight propofol since you have some analgesia from the K. I typically give no BZD's or narcs. I haven't had any pts c/o unpleasant emergence phenomenon but a couple have thanked me for the amazing experience and said they have never felt like that before, but it's always been a positive feeling. I even had one straight female pt hitting on the female PACU nurses as she was waking up. We do a lot of low EF AICD implants and it works great for those. I'll use the above recipe as the sole anesthetic for D&C's with great results too (the women's ctr PACU staff tells me they have way less pain and nausea than a traditional anesthetic). Wake-ups are not quite as snappy as with propofol alone, but it's nothing that's really clinically significant. A little more groggy for the first 10-15 min but they're still perky and ready to go by the time the 30min mark gets there and nobody spends less that 30min in PACU anyways at my shop.

I'll use ketofol for neuromonitoring cases as well, but then I'll only add 100mg to the 100mL propofol as others have mentioned. Since it augments the signals, I can get away with a little more gas and a little less prop which in my hands equates to snappier more predictable wake-ups. Plus, the neuromonitoring girls get a little moist when you tell em your gonna run ketamine.

Thanks Blade for posting some of the negative studies on ketamine. I think people have gotten a little too gung ho on the pro-adjuvant "narcotics are evil" train over the last few years. Ketamine makes sense in the narcotic tolerant chronic painers who have already maxed out their mu pathways and can benefit from some NMDA action because that's all that's left. I don't think it adds much if at all for the average opioid naive pt. Even the studies which show narcotic sparing benefit while statistically significant are not overly impressive from a clinical standpoint. I mean, so what if the ketamine group used 5mg less of morphine peri-operatively?

I'm also not sure why people expect a little ketamine at the start of the case to have significant effects post-op. You don't expect any of your other drugs to have any relevant effects after 4-5 half lives so why is ketamine is so magical?

 

[sevoflurane]

1/2 life of ketamine is 2.5 hrs. That's a good reason to use it in my book. I don't use it "pre-operatively or post-operatively".
I use it intra-operatively. A little goes a long ways.

 

[risnwb]

I use the same concentration as salty dog, 50mg of ketamine in a 20ml syringe of propofol. I use it for ESWL on occasion and it works great. Often if I get it off in time I can put them in a wheelchair and bypass pacu. Also use it for regional cases where the patients might be a little jumpy-keeps them still and spontaneous better than propofol alone. If they start moving I'll bolus 10-20 mg of ketamine and they calm right down. No problems with dysphoria.

 

[BLADEMDA]

I use the same concentration as salty dog, 50mg of ketamine in a 20ml syringe of propofol. I use it for ESWL on occasion and it works great. Often if I get it off in time I can put them in a wheelchair and bypass pacu. Also use it for regional cases where the patients might be a little jumpy-keeps them still and spontaneous better than propofol alone. If they start moving I'll bolus 10-20 mg of ketamine and they calm right down. No problems with dysphoria.

Your "dose" is twice the amount typically recommended in most studies. I would tread carefully here and keep the total dose to under 150 mg for the case.
Since your cases are short you can get away with 2.5 mg/ml of Ketamine mixed into the propofol but for longer cases the 1 mg/ml mixture is better.
Most studies use 6-10 ug/kg/min of propofol after the bolus dose 0f 0.3-0.5 mg/kg; this translates into no MORE than 1 mg/ml of Ketamine with the propofol.

Your mixture works because the total dose is kept low as the cases are under 1 hour. I would argue that an additional bolus of 20 mg ketamine IV as needed while maintaining a 1 mg/ml mixture with the Propofol is superior. FYI, I draw up 3 bottles of propofol or 60 mls and add 50 mg of Ketamine to the mixture for about 0.83 mg/ml in order to better maintain the recommended 6-10 ug/kg/min infusion rate. IMHO, low dose Ketamine is all you need for most cases.

Again, for short cases the mixture doesn't matter as much as long as the total dosage is held in check to 100-150 mg (100 mg or less is better for short cases).

 

[risnwb]

Your "dose" is twice the amount typically recommended in most studies. I would tread carefully here and keep the total dose to under 150 mg for the case.
Since your cases are short you can get away with 2.5 mg/ml of Ketamine mixed into the propofol but for longer cases the 1 mg/ml mixture is better.
Most studies use 6-10 ug/kg/min of propofol after the bolus dose 0f 0.3-0.5 mg/kg; this translates into no MORE than 1 mg/ml of Ketamine with the propofol.

Your mixture works because the total dose is kept low as the cases are under 1 hour. I would argue that an additional bolus of 20 mg ketamine IV as needed while maintaining a 1 mg/ml mixture with the Propofol is superior. FYI, I draw up 3 bottles of propofol or 60 mls and add 50 mg of Ketamine to the mixture for about 0.83 mg/ml in order to better maintain the recommended 6-10 ug/kg/min infusion rate. IMHO, low dose Ketamine is all you need for most cases.

Again, for short cases the mixture doesn't matter as much as long as the total dosage is held in check to 100-150 mg (100 mg or less is better for short cases).

Appreciate the feedback, will try 1mg/ml mixture. As far as using ketamine to hit the NMDA receptors for chronic pain patients undergoing spines surgery for example, how much would you give per hour roughly? I've been giving a Bolus of 20 mg prior to incision and then a 10 mg bolus every hour...

 

[psychbender]

Appreciate the feedback, will try 1mg/ml mixture. As far as using ketamine to hit the NMDA receptors for chronic pain patients undergoing spines surgery for example, how much would you give per hour roughly? I've been giving a Bolus of 20 mg prior to incision and then a 10 mg bolus every hour...

On average, I go with maybe 150-300mcg/kg/hr, but I've doubled that on some select patients without adverse effects. I used to have some guys on 40mg/hr infusions sitting on the ward, going about their day, and no one complained of hallucinations/agitation/nightmares (at least, not more than the rest of their cohorts with not-yet-diagnosed combat-related PTSD).

 

[deleted171991]

On average, I go with maybe 150-300mcg/kg/hr, but I've doubled that on some select patients without adverse effects. I used to have some guys on 40mg/hr infusions sitting on the ward, going about their day, and no one complained of hallucinations/agitation/nightmares (at least, not more than the rest of their cohorts with not-yet-diagnosed combat-related PTSD).

In my limited experience, some patients tolerate high doses of ketamine without an issue. In one CRPS patient, I ran 0.7 mg/kg/hr on the floor, for a couple of days, and the patient was perfectly alert and oriented (and pain- and opiate-free).

 

[deleted171991]

Appreciate the feedback, will try 1mg/ml mixture. As far as using ketamine to hit the NMDA receptors for chronic pain patients undergoing spines surgery for example, how much would you give per hour roughly? I've been giving a Bolus of 20 mg prior to incision and then a 10 mg bolus every hour...

The analgesic dose is 0.1-0.2 mg/kg/hr. You can give it as an infusion or as an hourly bolus, no big difference.

 

[BLADEMDA]

The studies seem to suggest a bolus of 0.5 mg/kg upfront followed by 10 ug/kg/min for patients with preexisting pain issues.


http://www.ncbi.nlm.nih.gov/pubmed/20693876

 

[fakin' the funk]

1/2 life of ketamine is 2.5 hrs. That's a good reason to use it in my book. I don't use it "pre-operatively or post-operatively".
I use it intra-operatively. A little goes a long ways.

If you have some evidence to support this figure, I'd love to see it.

Not that I'm beefing with you, I simply haven't been able to find good, reliable data on ketamine kinetics.

My impression clinically is that boluses and infusions have a duration longer than propofol, but shorter than fentanyl.

 

[BLADEMDA]

Following intravenous administration, the ketamine concentration has an initial slope (alpha phase) lasting about 45 minutes with a half-life of 10 to 15 minutes. This first phase corresponds clinically to the anesthetic effect of the drug. The anesthetic action is terminated by a combination of redistribution from the CNS to slower equilibrating peripheral tissues and by hepaticbiotransformation to metabolite I. This metabolite is about 1/3 as active as ketamine in reducing halothane requirements (MAC) of the rat. The later half-life of ketamine (beta phase) is 2.5 hours.

The anesthetic state produced by ketamine has been termed "dissociative anesthesia" in that it appears to selectively interrupt association pathways of the brain before producing somesthetic sensory blockade. It may selectively depress the thalamoneocortical system before significantly obtunding the more ancient cerebral centers and pathways (reticular-activating and limbic systems).

 

[BLADEMDA]

The redistribution half life is 10-15 minutes

The Ketamine "high" last for 45 minutes.

Elimination half life is 2.5 hours.

 

[BLADEMDA]

Anaesthesist. 1975 Jun;24(6):260-3.
Pharmacokinetics of ketamine in man.
Wieber J, Gugler R, Hengstmann JH, Dengler HJ.
Abstract
A method for the analysis of ketamine and of its metabolites is described using gas-liquid chromatography for separation and flame ionization detection. The lower limit of detection for ketamine in serum was 0.025 mug/ml. The pharmacokinetic behaviour of ketamine after intravenous injection may be described in terms of an open two-compartment model. The serum half-life of ketamine was in alpha-phase about 11 min, the predominant half-life for the beta-phase 2.5 h. The half-life of ketamine and its metabolities in urine was comparable to that in serum. It could be shown that the duration of anaesthesia is not only correlated ti ist rapid metabolic breakdown and elimination, but also to the distribution of the drug peripheral tissue.

 

[BLADEMDA]

Br J Anaesth. 1981 Jan;53(1):27-30.
Pharmacokinetics and analgesic effect of ketamine in man.
Clements JA, Nimmo WS.
Abstract
The pharmacokinetics and analgesic effect of i.v. ketamine in doses of 125 microgram kg-1 and 250 microgram kg-1 were determined in five healthy volunteers. Analgesia was measured with the submaximal effort tourniquet test. Both doses of ketamine prolonged the period of pain-free ischaemic exercise while the plasma ketamine concentration was greater than 100 ng ml-1. Ketamine was distributed rapidly (T 1/2 alpha = 17 min). The elimination half-life was 186 min.

 

[subtle1epiphany]

FYI, those extremely high doses of lorazepam and fentanyl are not unexpected when ECLS (ECMO) is involved. The tubing and membranes adsorb drugs according to their lipophilic nature. Fentanyl is highly lipophilic, ketamine I think is as well given how rapid the onset is and that it redistributes, attenuating the effect sooner than eliminated. Also remember that the circuit will directly increase the volume of distribution, as you mentioned already.

We really need to think of the circuit as another part of our patient. We always consider ventilator-patient interactions, there are circuit-patient interactions as well.

Nicely done!

...severe ARDS and MODS on VV ECMO, CVVHD and pressors. ... I'm guessing because of his increased Vd, he was requiring 600 mcg/hr of fentanyl and 15 mg per hour of lorazepam (a MICU favorite). Astronomically high in my opinion. But he was too agitated still and there were problems with the ECMO. Flows were inconsistent and low. We ruled out problems with the cannulas and fluid balance. But he was fighting the ventilator (conventional lung protective settings) and our thinking was that the elevated intrathoracic pressures were impeding flows. ... I suggested ketamine, managed to get pharmacy and nursing on board, gave him a bolus of 1 mg/kg and started an infusion at 0.5 mg/kg/hr (now at 1) and he did really well
Hemodynamics stabilized, flows stabilized, lungs look a little better since we're not pouring fluid into him. I don't suggest it as a first line agent in the ICU but as a rescue agent in super tolerant patients or patients on mechanical support, I like it so far.

 

[G-Man82]

FYI, those extremely high doses of lorazepam and fentanyl are not unexpected when ECLS (ECMO) is involved. The tubing and membranes adsorb drugs according to their lipophilic nature. Fentanyl is highly lipophilic, ketamine I think is as well given how rapid the onset is and that it redistributes, attenuating the effect sooner than eliminated. Also remember that the circuit will directly increase the volume of distribution, as you mentioned already.

We really need to think of the circuit as another part of your patient. We always consider ventilator-patient interactions, there are circuit-patient interactions as well.

Nicely done!

Thanks. Has been tough but we just decannulated him today. Was a milestone for him but he's definitely not out of the woods yet. Now that he's been on Ativan and Fentanyl for days and days (not to mention atracurium for the past 7 days with steroids), I'm trying to see if I should just shut everything off cold turkey and gauge his response in true sedation vacation style or if this prolonged use of benzos and opioids requires a slower titration. It's awful. He's 30 and as of now, I have no idea what his mental status is like. His lungs are still not the best but with the bleeding we had to get him off ecmo and the heparin drip. 50% and 15 peep. Plateaus about 30-32, but he's a little bigger so we're accepting that.

I think the ketamine drip served it's purpose, that's for sure.

 

[agammaglobulin]

I disagree completely with the above post. Ketamine is a great drug and is vastly underutilized by most Anesthesiologists. I encourage everyone to use Ketamine (low dose) for many situations:

1. Low EF- great induction agent with propofol (0.5 mg/kg propofol and 0.5 mg/kg ketamine)
2. Great sedative for ASA4 cases like EGD ( ketamine 20-30 mg IV bolus then mix the ketamine in with the propofol at 1 mg/ml)
3. Great for Chronic Pain Patients- Higher doses can be used here up to 200-250 mg over a 2 hour period
4. Neuromonitoring cases- Great to add the ketamine to the propofol
5. Awake Intubation- Glyco, Ketamine (30-50 mg), Precedex and Versed go a long way when given in COMBINATION/Synergism
6. Elderly Patients with Dementia- Regional with Ketafol may decrease morbidity and mortality


Some studies suggest Ketamine 0.3-0.5 mg/kg bolus followed by an infusion of 1-10 ug/kg/min as Ketamine has a redistribution half life of 10-15 minutes.
I usually just give bolus and mix the ketamine with the propofol at 1mg/ml of ketamine but the purists may want to know that some studies suggest infusions of 2-8 ug/kg/min of ketamine after the bolus.

My personal limit of Ketamine is in the 150-200 mg range over 2 hours (non Chronic pain patients). In addition., small bolus doses don't typically cause HTN or tachycardia even in critically ill patients or those with low EF (I've seen a brief hypertensive response only once after a 30 mg IV bolus of Ketamine out of several thousand patients and that was possibly because I gave the Ketamine BEFORE the Propofol)

Opioid Naive patients don't need more than 2-6 ug/kg/min of Ketamine while Opioid users (Chronic pain) may benefit from a higher infusion rate of 6-10 ug/kg/min. Personally, I stick with LOW DOSE ketamine in order to avoid any side-effects from the drug.

Great post. Are you ever concerned about using Ketamine in low EF situations in regards to hypotension? I've heard (but not seen) that sympathetically depleted patients (ICU, CHF) can experience the mild cardiac depressant effects of ketamine without the increase sympathetics to compensate, causing hypotension.

 

[BLADEMDA]

Great post. Are you ever concerned about using Ketamine in low EF situations in regards to hypotension? I've heard (but not seen) that sympathetically depleted patients (ICU, CHF) can experience the mild cardiac depressant effects of ketamine without the increase sympathetics to compensate, causing hypotension.

Yes, unfortunately I've seen hypotension with the use of ketamine in the patirnts you describe above. The way I see it though is that any induction agent other than scopolamine would cause hypotension in that group. That's why you need to bring vasopressin in a syringe (1 unit per ml) to treat the hypotension in those types of patients.

 

[Jay K]

Is anyone using or has used ketamine as the sole anesthetic for GA? If so, are you securing the airway? (i apologize in advance if I'm taking this thread too far off topic)

Yes.

Unconsolable, screaming, fairly uncooperative, pacing, morbidly obese middle-aged patient with intractable back pain and unable to lay supine for L-spine MRI, failed sedation previously.
1) Midazolam 2mg
2) Glycopyrrolate 0.2mg
3) Ketamine 1.5mg/kg bolus

Spontaneous respirations in the MRI on NC, stayed perfectly still, no recall and woke right up the moment we pulled pt out of the MRI, no adverse effects

-----

Ketafol is one of my favorite anesthetics. Premed with Midazolam and Glycopyrrolate. Typically mix Ketamine 1mg/1ml of Propofol and titrate to effect starting high (i.e. 200-250mcg/kg/min propofol) then titrating down as case progresses. If the patient has high benzodiazepine and/or narcotic use and/or alcohol use, or weighs a lot, I may choose to mix Ketamine 2mg/1ml Propofol as my infusion.

I also use ketamine boluses and infusions as adjuncts to multi-modal analgesia. Short cases I will typically bolus 1mg/kg up front. Longer cases bolus 0.5mg-1mg/kg then run infusion at 10mcg/kg/min. I typically shut off the infusion 45" prior to case end. Have not experienced prolonged emergence or other side effects. I will re-dose midazolam mid-case on long infusions/long cases. I have no problem administering >400mg ketamine doses for long cases, although admittedly that is very rare.

-----

Ketamine boluses are also very effective for the working spinal/epidural during c-section, yet with the anxious, unconsolable, screaming emotionally-decompensating patient that still cannot tolerate the pushing/tugging that is not abolished by the neuraxial blockade.

 

[G-Man82]

Just thought I'd mention. The VV ECMO patient I spoke about? He actually "walked" out of the hospital. Got critical illness neuropathy, but he's alive and well probably given his Age: 33. Diagnosis was leptospirosis, proven by PCR. His family is very appreciative, and I love that. I just want to point out that even as Anesthesiologists, in the ICU, our patients get to know us and appreciate us a lot.

I asked him if he remembered much about the ecmo and his condition a few weeks ago. His response was that he had some bad dreams. 22 days on Ecmo, and 7 of those days on ketamine + Lorazepam + fentanyl. The ketamine was up to 1.9 mg/kg/hr. Despite lorazepam, still had nightmares. But he didn't care at the end. I'm just glad he left the hospital NOT in a coffin.

 

[propadope]

Wanted to see what the various ketafol fans out there are doing for their clinical situations they use it in, concentrations, doses, and experiences. (That oddly sounds like an erowid question, but I'm asking about clinical use)

It's very hard to find info on context sensitive half times for ketamine infusions. I think given that it's very lipophilic, short duration, and duration of boluses are determined by redistribution, i.e., like propofol, it's reasonable to run the two together and essentially treat ketamine's kinetics like propofol's.

In a few old posts, members have said they dilute ketamine to 1 mg/ml in their propofol bottle then just run the prop. If you are running propofol up to, say, 100 mcg/kg/min putting your ketamine at 10 mcg/kg/min (i.e. 0.6mg/kg/h), are you seeing a lot of delayed wakeups, delirium, or other untoward side effects upon wakeup? How long before case end do you shut it off? Any situations where you'd use more or less, or run them separately?

I love me some ketafol. I agree with predetermining the rate of propofol infusion and then adjusting the ketamine concentration accordingly to obtain 2-10ug/kg/min. This is all depending on if you are doing minimal, moderate, deep sedation or general anesthesia; the procedure and patient. This has all been mentioned by you all.

However I don't agree that is difficult to find information on ketamine pk and context sensitive half times

This is readily available. If you notice, ketamine actually has a shorter csht until the 2hr mark. So what I would do is after a 2hr infusion, reduce the concentration of ketamine in the admixture. Also plan for the emergence/recovery. Do you want the effects of the ketamine just intraop or also into the post op period?

J

 

[Impromptu]

I have found that you can inject a 200mg/20ml vial of ketamine into a 1000mg/100 ml vial of propofol, shake well, then run on an infusion pump.

 

[BuzzPhreed]

Not a big ketafol fan, personally. I think it adds cost in the form of time, med accountability issues, and (although nominal) money to the anesthetic. We recently had one of our practitioners (who has used ketafol for at least 20 years) try to "experiment" with it for outpatient colonoscopies. It was a disaster. Noticeable delays in discharge home. So much so that, the day(s) he did this, there was a collective "WTF" murmuring in the department.

Ketamine has a role in patients with a high baseline tolerance to narcotics or with extremely painful procedures... or when all else fails. I will run ketafol for big spine cases that require neurmonitoring. If the patient is just have a straight non-fusion back and a high narcotic requirement, I will give a bolus up front at the beginning of the case usually 0.25mg/kg. That's about the only time I use it.

Then again, I'm a "less is more" kind of practitioner. I also don't routinely have patients puking, confused, with intractable pain, delirious, or any other host of problems that require ongoing intervention and delay of discharge from the PACU.