Two prior concerns stemming from anecdotal information that predated its use in the TCCC setting were a concern over possible increased intracranial pressures in head trauma victims and increased intraocular pressures. However, several studies have subsequently been carried out demonstrating that neither concern is valid, and ketamine can safely be used in head injuries and eye injuries.
At the higher doses used for anesthesia, moderate to deep sedation occurs, and there is a risk of a dissociative reaction entailing distorted perceptions of sight and sound which produce feelings of detachment. But at normal analgesic doses, this has not been shown to occur. This can be treated with midazolam by Combat Paramedics or providers.
Another side-effect, also normally seen in higher doses than the analgesic dose, is an emergence reaction, where a casualty may make spontaneous utterances and purposeless motions or exhibit agitation. This may require temporary restraints for the casualty, but can also be significant enough to warrant treatment with midazolam.
The effects of ketamine are increased when combined with other analgesics or muscle relaxants.
The Onset/Peak/Duration for ketamine is 30 sec-4 min (IV<IO<IN<IM)/1-10 min/5-25 min.