Ketamine Treatment Protocol
The ketamine infusion treatment protocol consists of conscious sedation with ketamine over a 2-hour period. Typically, pretreatment with 0.2 mg of glycopyrolate IV is the only other drug necessary.
A ketamine drip is administered at 100 mg / hour supplemented with 5-40 mg IV bolus injections of ketamine. An average adult will require a total of 400-600 mg of ketamine over a two hour period in order to maintain an adequate depth of conscious sedation. Midazolam is usually not necessary. Bad dreams (hallucinations) can occur in patients with RSD during the 2-hour ketamine infusion.
Some patients will obtain relief of pain at a lower infusion rate of ketamine (10-30 mg/hour)
Typically, the infusion rate in an adult for a 2-hour ketamine infusion is 100 mg / hour. It is important to recognize that the elimination half-life for ketamine is 3-5 hours. Accordingly, it may take 4 half-lives (at least 12 hours) to reach a steady-state (or peak) blood level. [5] Therefore, initial titration with loading (bolus) doses of 5 to 40 mg ketamine are required to obtain adequate anesthesia during the early phase of the 2-hour infusion. Incremental doses are added until the desired effect is achieved such as signs of mental dissociation and nystagmus. (See "SPECIAL CONSIDERATIONS" #1 below regarding adequate anesthesia for a low-dose infusion)
If necessary, keep the mouth dry with glycopyrolate (Robinol 0.2 mg IV doses) and/or suction. This treatment can easily take place in the PACU with a significant other by the bedside to re-assure the patient. Routine monitoring for these patients typically includes BP and pulse oximetry.
Midazolam (Versed) will probably not be necessary to counteract the hallucinogenic effects of ketamine in patients with RSD. If unpleasant hallucinogenic effects occur with ketamine, 1 to 6 mg of IV midazolam should be given just prior to the ketamine infusion.
During recent years, it has become increasingly clear that long-term or escalating opioid use does not lead to improvement of function in every patient. Case studies of pain report that opioids actually increase pain in some patients as a consequence of injury or surgery, often associated with a modification of the pain character and an extension of the affected region that may persist for days, weeks, or even years.