Ketamine+Propofol: 1st time users
Background
1. For ketamine users, the combo can’t be safer, but you get less emergence reactions, less vomiting, & better satisfaction (Parents, MD’s, RN’s).
2. For Propofol users, you get less hypoxia/respiratory problems, less BP problems, smoother sedation (see David H, Shipp J: Ann Emerg Med. 2011;57: fig. 4 on p. 439) & better satisfaction (MD, RN).
3. The combo can be used for most, but not all situations.
a. Ketamine is “probably” safe in Pts with head & eye trauma & intoxicated Pts. It should avoided in pregnancy, psychotic/psychiatric, known intracranial masses/bleeds, & super high blood pressures.
b. Propofol should be avoided in those with low BP, volume depletion, egg or soybean allergies. It is not my choice with conditions/positions/procedures that would be difficult to bag (tongue lacs, face down for butt I&D’s, etc.).
c. I have used ketamine-propofol for pediatric butt I&D’s, when I was able to position the pt on their side.
d. For certain ultra-short procedures (sync cardioversion), you may want to just use propofol. For long procedures (big wounds), you might consider straight ketamine (if you are almost done, and the pt is starting to move, consider a propofol chaser, rather than a last dose of ketamine).
How to
Residents are required to have faculty present for all procedural sedation.
The pharmacological advantages of 2 syringes, clearly out-weights the convenience of the single syringe.
If ketamine is given 1st, the burning sensation with IV propofol is negated/blunted.
Ketamine has a longer onset of action & duration of action, so giving it 1st, allows a timely, rationale synergy.
Both drugs should be pushed slowly, which is really, really hard to do, but it avoids complications like emergence reactions, bronchospasm, & apnea.
0.5 mg/kg ketamine should be given over 30-45 secs. If giving a higher dose of ketamine, give over 1-2 min.
0.5 mg/kg of propofol should be given over 30-45 secs as well. Again, higher doses should be given over 1-2 mins.
After the ketamine is in, I usually wait a min & check the pt’s level of sedation. Rarely, no propofol is needed.
Dosing
Not enough research has been done on this, so I’m learning as I go along.
For the obese, should we be using lean body wt or actual wt? I usually split the difference, but this isn’t evidence based & may not be ideal.
Should doses be reduced with to pre-existing opioids/ETOH? Makes sense, but with the safety & titration of 2 syringe ketamine-propofol, I haven’t been making any major adjustments.
Standard dosing is 0.5 mg/kg ketamine, followed by 1-2-3-4-5 doses of 0.5 mg/kg propofol.
To me, younger kids need more repeat propofol dosing, so a higher initial dose of ketamine could be considered. In younger kids, I’m using 0.75 mg/kg of ketamine, followed by the standard 0.5 mg/kg propofol doses. Almost always, I then need only 1 or 2 propofol doses. When does a small kid become a bigger kid? I don’t know. (Age 5? Age 10? Age 15?)
To me, older pts need less ketamine. Although they are completely stable, a few have had a prolonged recovery time. Prolonged recovery time was also be seen in kids (Shah A, et al. Ann Emerg Med. 2011;57: fig 2 on p. 429.). Right now, I’m using 0.33-0.4 mg/kg ketamine, followed by the standard 0.5 mg/kg propofol. Again, usually 1 propofol dose (or sometimes 2) gets the elderly to the needed level of sedation. When does an adult become “older”? Here again, I don’t know. (Age 50? Age 60? Age 70?)