Preemptive ketamine use is based on the concept the brain cannot respond (or windup) to information it does not receive. 50 mg ketamine 2-3 minutes pre-skin stimulation (i.e. incision or local analgesia injections) blocks 98-99% of midbrain NMDA receptors, denying the cortex knowledge of the invasion of the protected world of self by the outside world of danger.
Dose & timing both essential to triumph over postoperative pain.
Intra-operative ketamine use is analogous to intra-operative use of opioids that does nothing to block midbrain NMDA receptors PRIOR to stimulation, leading to windup and postoperative pain management issues.
Preemptive ketamine use has prevented hospitalizations for postoperative pain management in >6,000 patients for the past 25 years.
How do you think, dose of 0.15/kg is effective for preemptive use of ketamine? or only 50 mg? What is your opinion about latest article that was publishes in Lancet about ketamine? Thank you
Ketamine is unique among all IV anesthetics. It is not body weight dependent. Why? Because the NMDA receptors are a small part of the tiny midbrain in a total brain size that does not vary with body weight. For example, the brain weight of a 200# male is not twice that of a 100# female.
As to my 'nifty 50' dose, having watched 250# men & 120# women lie perfectly immobile with the same 50 mg dose, I concluded (before knowing anything about NMDA receptors) that the effective dose has nothing to do with body weight.
Started c 75 mg, empirically reduced to 50. Even tried 25 but found 20% were not immobile & needed to add an additional 25 to produce immobility.
Immobility in response to incision or multiple local anesthetic injection is evidence of effective preemptive ketamine. With BIS/EMG monitoring, add absence of EMG spike is numerically reproducible evidence of NMDA saturation & non-opioid, preemptive analgesia.
As to my feelings about the ketamine article, I submitted a formal response that I hope will get published when the article appears in print.
Stay 'tuned' & that you for your interest.
I started preemptive Ketamin for medium and longer procedures in urology during general or combined epidural and general anesthesia. In this moment I am using it with other analgesic modalities as a part of multimodal regime. I would like to ask what are the shortest procedures that you use dissociative Ketamin for. Of course I am asking for combining it with propofol as induction agent?
Thank you for accepting my gift but I suspect your patients are even more grateful. Twenty minutes, preferably 30 if possible.
Absence of EMG spike c incision is evidence of midbrain NMDA receptor saturation & non-opioid, preemptive analgesia.
Best wishes!
Yes, in shorter procedures I found out that special awakening, characteristic for Ketamin.
Would you be so kind to give me some literature about last pdf, and constatation (about EMG spikes)?
Thank you in advance!
After a frustrating year '97-'98 trying to get the hang of using the BIS monitor, the salesman recommended trending EMG as a secondary trend. After a short while, I noticed the EMG spike preceded any HR or BP changes. I postulated that EMG was a signal of incipient arousal & went on from there.
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