The Effect of Drug Concentration Expression on Epinephrine Dosing Errors

The Effect of Drug Concentration Expression on Epinephrine Dosing Errors

A Randomized Trial

From the University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom, and Benito Menni—Centre Assistencial en Salut Mental Sant Boi de Llobregat, Barcelona, Spain.

Abstract

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 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).

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.

Article and Author Information

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, dww21{at}cam.ac.uk.
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.