While looking for references for a talk on ketamine, I found a study on emergence phenomena. One aspect of emergence phenomena is the state of emotional distress, the nightmare or simply the bad trip that sedated patients risk being trapped in after being sedated with ketamine.
The prospective, randomised and blinded study in the february issue of Annals of Emergency Medicine 2011 demonstrates to what extent Midazolam reduces emergence phenomena when ketamine is used for procedural sedation. Patients were randomised into getting ketamin IV or IM with or without midazolam for premedication. The results are in the table below.
So if all patients received Midazolam the absolute reduction of recovery agitation would be 17% and the number needed to treat is 6.
One problem with this study is how all perceived recovery agitation was defined as a positive regardless of severity. A soft moan or transient movements would be defined as recovery agitation.
So all this study might tell us is that Midazolam reliably reduces the number of bad trips to roughly a third if given as premedication. It does not give us an idea of how frequent bad trips are.
The study, however, also provides us with satisfaction rates for the physicians, nurses and patients.
Patients are happier with Midazolam premedication.
So does this mean all patients should receive Midazolam before having Ketamine? Not at all. For procedural sedation in healthy patients…maybe…yes. For the traumatised patient or the critically ill way more caution is needed. In those cases, midazolam could end up as just another factor when trouble-shooting a patient.
Study lives here.
Sener S et al. Ketamine With and Without Midazolam for Emergency Department Sedation in Adults: A Randomized Controlled Trial. Ann Emerg Med. 2011;57:109.