In this episode, I’ll discuss why I think ketamine and propofol don’t belong in the same syringe.
Ketamine and propofol are compatible in the same syringe, and several published studies have specifically stated that the two medications were placed in the same syringe.
But just because we can, doesn’t mean we should.
These two medications frequently given together for procedural sedation in the Emergency Department and elsewhere. This combination is sometimes called “ketofol”.
In this combination, propofol serves to provide sedation while ketamine serves to provide analgesia without increasing the respiratory depressant effects of propofol. An additional benefit of the combination is that the hypotension from propofol may be partially offset by the positive cardiovascular effects of ketamine.
Indeed, the previously described meta-analysis support that ketamine plus propofol results in fewer episodes of bradycardia and hypotension than propofol alone. Ketamine-related psychomimmetic side effects don’t appear to occur more frequently than in the propofol monotherapy group, or at least the difference is not statistically significant.
The ratio of ketamine to propofol varies widely with some studies using 1:1, some using 1:10, and several more at various points in between this range.
The problem I have with placing ketamine and propofol together in the same syringe comes when this practice is taken from a controlled study environment to a real-world setting.
The analgesic effects of ketamine may last up to 90 minutes, while the sedative effects of propofol will only last a few minutes. With two different durations of action in the same syringe, what happens when the procedure goes a bit longer than planned and more sedation is needed? The clinician is forced to give more ketamine even though all that was needed was propofol. Worse yet, if more analgesia is called for, the clinician needs to give it along with more propofol, raising the risk of respiratory compromise for no good reason.
While most of the time, a serious adverse event will not occur when a second dose of “ketofol” is given to provide more analgesia or more sedation, that’s not the point. The point is that the risk of adverse event is raised for a capricious reason that is easily avoidable by using 2 syringes. In my opinion, there is no need to take this risk and ketamine and propofol belong in two separate syringes, even when used together for procedural sedation.
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