title: Comparison of the effects of ketamine and morphine on performance of representative military tasks.
abstract: BACKGROUND
  When providing care under combat or hostile conditions, it may be necessary for a casualty to remain engaged in military tasks after being wounded. Prehospital care under other remote, austere conditions may be similar, whereby an individual may be forced to continue purposeful actions despite traumatic injury. Given the adverse side-effect profile of intramuscular (i.m.) morphine, alternative analgesics and routes of administration are of interest. Ketamine may be of value in this capacity.
  
  
  OBJECTIVE
  To delineate performance decrements in basic soldier tasks comparing the effects of the standard battlefield analgesic (10 mg i.m. morphine) with 25 mg i.m. ketamine.
  
  
  METHODS
  Representative military skills and risk propensity were tested in 48 healthy volunteers without pain stimuli in a double-blind, placebo-controlled, crossover design.
  
  
  RESULTS
  Overall, participants reported more symptoms associated with ketamine vs. morphine and placebo, chiefly dizziness, poor concentration, and feelings of happiness. Performance decrements on ketamine, when present, manifested as slower performance times rather than procedural errors.
  
  
  CONCLUSIONS
  Participants were more symptomatic with ketamine, yet the soldier skills were largely resistant to performance decrements, suggesting that a trained task skill (autonomous phase) remains somewhat resilient to the drugged state at this dosage. The performance decrements with ketamine may represent the subjects' adoption of a cautious posture, as suggested by risk propensity testing whereby the subject is aware of impairment, trading speed for preservation of task accuracy. These results will help to inform the casualty care community regarding appropriate use of ketamine as an alternative or opioid-sparing battlefield analgesic.
authors.affiliation: U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Gaydos
authors.affiliation: U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama.
authors.forename: Amanda M
authors.initials: AM
authors.lastname: Kelley
authors.affiliation: U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Grandizio
authors.affiliation: U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama.
authors.forename: Jeremy R
authors.initials: JR
authors.lastname: Athy
authors.affiliation: U.S. Army Aeromedical Research Laboratory, Fort Rucker, Alabama.
authors.forename: P Lynne
authors.initials: PL
authors.lastname: Walters
mesh_terms: D000328:Adult; D000700:Analgesics / Q000494:pharmacology*; D000701:Analgesics, Opioid / Q000494:pharmacology; D018592:Cross-Over Studies; D004244:Dizziness / Q000139:chemically induced; D004311:Double-Blind Method; D005260:Female; D006240:Happiness; D064368:Healthy Volunteers; D006801:Humans; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D008887:Military Medicine; D008889:Military Personnel; D009020:Morphine / Q000494:pharmacology*; D012309:Risk-Taking; D013647:Task Performance and Analysis; D055815:Young Adult
chemical_list: D000700:Analgesics; D000701:Analgesics, Opioid; D007649:Ketamine; D009020:Morphine
keywords: military medicine; prehospital care; soldier skills