Researchers at the Cambridge University have revealed that doctors treating life-threatening emergencies such as allergy attacks might give the wrong dosage of adrenaline (epinephrine) because of confusing labelling.
Adrenaline, which is used to treat emergencies such as asthma attacks, is stored in salt water in glass ampoules, with the amount contained usually expressed as both a dose and a ratio on the label.
The ratio requires arithmetic to work out how much drug to administer. Therefore, doctors understand doses much better than ratios.
During the study, Dr Daniel Wheeler at the university found that having to do extra calculations to figure out how much adrenaline to give a person in an emergency might lead to the errors and delays, which are common in administering the drug.
"It is well documented that patients are commonly given the wrong dosage of adrenaline," Dr Wheeler said.
To find out whether the labelling was indeed the cause of the high number of dosing errors, the research team set up mock scenarios.
They programmed a medical mannequin to look like it was having a life-threatening allergic reaction and doctors were then given ampoules of adrenaline and were told to treat the emergency.
One half of the doctors were randomly assigned to ampoules with labels that had the adrenaline dose while the other half were randomly assigned to ampoules with labels that had the amount of adrenaline expressed as a ratio.
The researchers then measured the amount of drug the doctors gave and how long it took them to give it.
It was found that out of 14, 12 doctors whose ampoules with labels that expressed the amount of adrenaline as a ratio overdosed their patients because they had to figure out how much drug to give.
The doctors using ampoules labelled with a ratio also took about 1.5 minutes longer to give it.
"The findings might be different if the doctors had to treat a real person. In reality, the labels have doses and ratios, not one or the other. However, this does give us insight into the problem and a fairly easy solution - expressing drug concentrations exclusively as doses we believe would improve patient safety," Dr Wheeler said.
The study is published in the Annals of Internal Medicine.