Effects of peritraumatic ketamine medication on early and sustained posttraumatic stress symptoms in moderately injured accident victims

Rationale: Ketamine, an N-methyl-D-aspartate receptor antagonist, produces transient dissociative and psychotic states in healthy humans that resemble symptoms shown by subjects with acute and chronic posttraumatic stress disorder (PTSD). Since ketamine is widely used as an analgesic and sedative in emergency care, it might be one factor triggering, modulating, or exacerbating PTSD in accident victims when given in the acute trauma phase. Objectives: The purpose of the present study was to determine whether the peritraumatic administration of ketamine affects acute and sustained PTSD symptoms in accident victims. Methods: A sample of 56 moderately injured accident victims was screened retrospectively for acute (Peritraumatic Dissociative Experiences Questionnaire; Acute Stress Disorder Scale) and for current PTSD symptoms (Impact of Event Scale) approximately 1 year postaccident. All subjects had received a single or fractionated dose of either racemic ketamine (n=17), (S)ketamine (n=12), or opioids (n=27) during emergency ambulance transportation. Results: Retrospectively assessed acute symptomatology was strongly increased in (S)-ketamine subjects in terms of dissociation, reexperiencing, and avoidance, and slightly heightened in racemic ketamines. Current PTSD symptoms were substantially elevated in (S)ketamine subjects, while there was no difference observed between opioids and racemic ketamines. Medication groups did not differ in regard to demographic variables, previous or postaccidental traumatic events, time between accident and investigation, and injury severity. Conclusions: The data provide first evidence for a modulating effect of a single-dose ketamine on the severity and duration of posttraumatic stress symptoms in accident victims.