Prehospital Agitation and Sedation Trial (PhAST): A Randomized Control Trial of Intramuscular Haloperidol versus Intramuscular Midazolam for the Sedation of the Agitated or Violent Patient in the Prehospital Environment

Abstract

Introduction: Violent patients in the prehospital environment pose a threat to health care workers tasked with managing their medical conditions. While research has focused on methods to control the agitated patient in the emergency department (ED), there is a paucity of data looking at the optimal approach to subdue these patients safely in the prehospital setting. Hypothesis This study evaluated the efficacy of two different intramuscular medications, midazolam and haloperidol, to determine their efficacy in sedating agitated patients in the prehospital setting.

Methods: This was a prospective, randomized, observational trial wherein agitated patients were administered intramuscular haloperidol or intramuscular midazolam to control agitation. Agitation was quantified by the Richmond Agitation and Sedation Scale (RASS). Paramedics recorded the RASS and vital signs every five minutes during transport and again upon arrival to the ED. The primary outcome was mean time to achieve a RASS less than +1. Secondary outcomes included mean time for patients to return to baseline mental status and adverse events.

Results: Five patients were enrolled in each study group. In the haloperidol group, the mean time to achieve a RASS score of less than +1 was 24.8 minutes (95% CI, 8-49 minutes), and the mean time for the return of a normal mental status was 84 minutes (95% CI, 0-202 minutes). Two patients required additional prehospital doses for adequate sedation. There were no adverse events recorded in the patients administered haloperidol. In the midazolam group, the mean time to achieve a RASS score of less than +1 was 13.5 minutes (95% CI, 8-19 minutes) and the mean time for the return of normal mental status was 105 minutes (95% CI, 0-178 minutes). One patient required additional sedation in the ED. There were no adverse events recorded among the patients administered midazolam.

Conclusions: Midazolam and haloperidol administered intramuscularly appear equally effective for sedating an agitated patient in the prehospital setting. Midazolam appears to have a faster onset of action, as evidenced by the shorter time required to achieve a RASS score of less than +1 in the patients who received midazolam. Haloperidol offers an alternative option for the sedation of an agitated patient. Further studies should focus on continued investigation into appropriate sedation of agitated patients in the prehospital setting.

Keywords: CONSORT Consolidated Standards of Reporting Trials; ED emergency department; EMS Emergency Medical Services; IV intravenous; QT interval time between the start of the Q wave and the end of the T wave in the heart’s electrical cycle; RASS Richmond Agitation and Sedation Scale; agitation; ambulance; emergency care; emergency service; prehospital; psychiatric; psychomotor.