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Weighing in on the importance of kilogram-only measurements :

August 23, 2021

In emergency departments (EDs) and other health care settings, the option to weigh patients both in pounds and kilograms can open the door to errors in medication dosing. That is why advocates like pediatric emergency nurse Elizabeth Stone, Ph.D., M.S.N., FAEN, have been calling out the need to weigh patients in kilograms.

Dr. Stone is the lead author of an AAP-endorsed position statement (https://bit.ly/3zFXuUN) from the Emergency Nurses Association (ENA) highlighting how certain populations — including pediatric, neonatal and critical care patients — are at greater risk of adverse drug events and more vulnerable to the effects of errors resulting from incorrect weights. An incorrect weight recorded in the ED also can follow a patient throughout a hospital stay and after discharge.

To avoid confusion, the statement says patient weights should be measured, recorded, communicated and documented using kilograms only.

The ENA has issued several updates of the statement Weighing All Patients in Kilograms. The AAP also endorsed previous versions.

About 10 years ago, Dr. Stone’s former supervisor analyzed medical errors in the pediatric ED where they worked to see how many were caused by problems related to weight measurements.

“What we realized was that confusion was happening, even on a daily basis … because we had the option to weigh both in pounds and kilograms. Parents would always ask for weights in pounds, and just having the option to do both would cause nurses and physicians to sometimes make mistakes in what they said and what they documented, which could cause errors in dosing,” said Dr. Stone, liaison from the ENA to the AAP Committee on Pediatric Emergency Medicine, clinical assistant professor at University of North Carolina at Chapel Hill School of Nursing and a pediatric emergency nurse at WakeMed Hospital.

The errors usually would be detected, she said, but the facility is a children’s ED, where staff are “very aware of what children’s weights should be. I can’t imagine how big of a problem it is in other hospitals where they’re not as familiar with children,” she added.

Dr. Stone’s supervisor also discovered that the hospital error reporting system usually didn’t reveal if a dosing problem was based on weight, as medical errors were categorized more generally. It took a root cause analysis to reveal the problem.

Few studies include analyses that drill down to wrong weight as the cause of specific medical errors. This can make collecting evidence to communicate the problem to administrators challenging, according to the statement.

Cost and culture are other barriers. Replacing scales can be expensive, although an alternative is to lock scales in metric units, if possible.

Public resistance to adopting the metric system in this country also doesn’t help.

“The use of pounds is very common in the U.S.,” said Dr. Stone, “and using metric weights in health care settings can be confusing to the patients and families …. It’s basically just a big culture change.”

She said using kilograms is a matter of convincing stakeholders of its importance.


The following are among 12 recommendations in the position statement:

  • Scales in the ED should be configured to record weights in kilograms only. Conversion charts should be nearby for caregiver or patient reference.
  • Electronic health records (EHRs) in the ED should allow weight entries only in kilograms and be configured with hard stops that prevent drugs or prescriptions from being ordered without a weight documented in kilograms. Upgrades to EHRs should incorporate best practices for documenting weights, including kilogram-only weight fields and notification of substantial changes in weight.
  • Clinical decision support functions should be available for patients under age 18 years to allow comparison of entered weight with expected weight and provide alerts whenever underdose or overdose is suspected.
  • Order forms, prescriptions and other paper documents should prompt users to enter weight in kilograms.
  • As medical error reporting systems evolve, they should be able to capture weight-based medical errors without an in-depth root cause analysis.
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