Daniel W. Wheeler, PhD; Joseph J. Carter, MBChB; Louise J. Murray; Beverley A. Degnan, PhD; Colin P. Dunling, BSc; Raymond Salvador, PhD; David K. Menon, MD, PhD; Arun K. Gupta, PhD
Potential Financial Conflicts of Interest: None disclosed.
Reproducible Research Statement:Study protocol, statistical code, and data set: Available to approved individuals through written agreements.
Requests for Single Reprints: Daniel W. Wheeler, PhD, Division of Anaesthesia, University of Cambridge, Box 93, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, United Kingdom; e-mail, email@example.com.
Current Author Addresses: Drs. Wheeler, Carter, Degnan, Menon, and Gupta and Mr. Dunling: University Division of Anaesthesia and Department of Anaesthetics, University of Cambridge, Box 93, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, United Kingdom.
Miss Murray: Simulation Centre, Addenbrooke's Hospital Postgraduate Centre, Box 111, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, United Kingdom.
Dr. Salvador: Benito Menni–Centre Assistencial en Salut Mental, Dr Pujadas 38, Sant Boi de Llobregat, 08830 Barcelona, Spain.
Author Contributions: Conception and design: D.W. Wheeler, B.A. Degnan.
Analysis and interpretation of data: D.W. Wheeler, B.A. Degnan, R. Salvador.
Drafting of the article: D.W. Wheeler.
Critical revision of the article for important intellectual content: D.W. Wheeler, J.J. Carter, L.J. Murray, B.A. Degnan, C.P. Dunling, R. Salvador, D.K. Menon, A.K. Gupta.
Final approval of the article: D.W. Wheeler, J.J. Carter, L.J. Murray, B.A. Degnan, C.P. Dunling, R. Salvador, D.K. Menon, A.K. Gupta.
Statistical expertise: R. Salvador, D.K. Menon
Obtaining of funding: D.W. Wheeler
Administrative, technical, or logistic support: J.J. Carter, L.J. Murray, B.A. Degnan, C.P. Dunling.
Collection and assembly of data: D.W. Wheeler, J.J. Carter, L.J. Murray, B.A. Degnan, C.P. Dunling.
The expression of drug concentration as a ratio may cause dosing errors.
To examine the effect of ratio expressions on drug administration.
Randomized, blinded, controlled study.
Simulation center in an urban hospital.
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).
The amount of epinephrine given and the time taken to administer it.
Compared with providers using ampules with mass concentration labels, those using ratio labels gave more epinephrine (adjusted mean dose, 213 μg above target [95% CI, 76.4 to 350.1 μg]; P = 0.003), and took longer to do so (adjusted mean delay, 91 seconds, [CI, 61.0 to 122.1 seconds]; P ≤ 0.0001).
Performance in simulated scenarios may not reflect clinical practice. In reality, ampule labels provide both expressions of concentration.
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.
Wheeler DW, Carter JJ, Murray LJ, et al. The Effect of Drug Concentration Expression on Epinephrine Dosing Errors: A Randomized Trial. Ann Intern Med. 2008;148:11–14. doi: 10.7326/0003-4819-148-1-200801010-00003
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Published: Ann Intern Med. 2008;148(1):11-14.
Emergency Medicine, Hospital Medicine.
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