K etamine as a rescue treatment for severe acute behavioural disturbance : A prospective prehospital study

OBJECTIVE Rapidly and safely managing severe acute behavioural disturbance (ABD) in the prehospital setting is important for the welfare of both patient and prehospital clinician alike. We investigated the safety and effectiveness of ketamine as rescue sedation in patients with severe ABD. METHODS This prospective observational study investigated ketamine use by a state ambulance service as rescue sedation for patients with severe ABD who remained agitated following droperidol administration. The primary outcome was the proportion of adverse events (vomiting, hypersalivation, emergence, over-sedation, airway obstruction, laryngospasm, hypoxia, bradypnoea and intubation). Secondary outcomes included time to sedation, requirement for additional sedation and rate of successful sedation. RESULTS There were 105 presentations (males 69/102 [69%]; median age 31 years (16-83 years). The commonest causes of ABD were illicit drug (39%) and alcohol (33%) intoxication. The median total dose of intramuscular ketamine was 200 mg (interquartile range [IQR] 150-200 mg). There were 64 adverse events in 40 (38%) patients. Four had vomiting, two had hypersalivation, two had emergence, 15 were oversedated, four had hypoxia, three had bradypnoea and 16 were intubated. Sedation was achieved in 103 (98%) patients at a median time post-ketamine of 8 min (IQR 5-13 min). Additional sedation was administered to 41 patients (nine prehospital and 37 within 1 h of arriving to hospital). In 44 (42%) patients, ketamine successfully sedated the patient with no adverse effects and no ongoing sedation requirement. CONCLUSION The use of ketamine as rescue sedation in prehospital patients with severe ABD is effective. Adverse events are common but can be managed supportively.