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Medline ® Abstract for Reference 56

of 'Anaphylaxis: Emergency treatment'

The effect of drug concentration expression on epinephrine dosing errors: a randomized trial.
Wheeler DW, Carter JJ, Murray LJ, Degnan BA, Dunling CP, Salvador R, Menon DK, Gupta AK
Ann Intern Med. 2008;148(1):11.
BACKGROUND: The expression of drug concentration as a ratio may cause dosing errors.
OBJECTIVE: To examine the effect of ratio expressions on drug administration.
DESIGN: Randomized, blinded, controlled study.
SETTING: Simulation center in an urban hospital.
PARTICIPANTS: 28 physicians.
INTERVENTION: Participants managed a simulated pediatric acute anaphylaxis scenario by using epinephrine ampules labeled with mass concentration (1 mg in 1 mL) or a ratio (1 mL of a 1:1000 solution).
MEASUREMENTS: The amount of epinephrine given and the time taken to administer it.
RESULTS: Compared with providers using ampules with mass concentration labels, those using ratio labels gave more epinephrine (adjusted mean dose, 213 microg above target [95% CI, 76.4 to 350.1 microg]; P = 0.003), and took longer to do so (adjusted mean delay, 91 seconds, [CI, 61.0 to 122.1 seconds]; P<or = 0.0001).
LIMITATIONS: Performance in simulated scenarios may not reflect clinical practice. In reality, ampule labels provide both expressions of concentration.
CONCLUSION: The use of ratios to express drug concentration may be a source of drug administration error. Patient safety might be improved by expressing drug concentrations exclusively as mass concentration.
Division of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom. dww21@cam.ac.uk