The first goal of this Best Practice is to ensure, as much as possible, that the patient’s actual weight is obtained upon each admission or appropriate encounter. Many medication doses are based on the patient’s weight. Relying on a stated, estimated, or historical weight can cause inaccurate dosing (both under- and overdosing).
The second goal of the Best Practice is to standardize the measurement and communication of a patient’s weight using only metric units of measure (grams [g] and kilograms [kg]). Official product labeling for medications provides weight-based dosing using only the metric system (e.g., mg/kg, units/kg). Significant medication errors have occurred when the patient’s weight was communicated and/or documented in non-metric units of measure (pounds and ounces) and was confused with kilograms or grams.
Tips to Obtain Accurate Patient Weights
a) Weigh each patient as soon as possible on admission and during each appropriate* outpatient or emergency department encounter. Avoid the use of a stated, estimated, or historical weight.
- Have metric scales available in all areas where patients are admitted or encountered. Ensure the metric weight is documented in the medical record.
- Do not rely on a patient’s stated weight, a healthcare provider’s estimated weight, or a documented weight from a previous encounter unless a life-threatening situation where the delay could lead to serious harm. Encounters that involve laboratory and other services where medications are not prescribed or administered would be considered an exclusion to this definition.
b) Measure and document patient weights in metric units only.
- If scales can measure in both pounds/ounces and kilograms/grams, modify the scale to lock out the ability to weigh in pounds/ounces.
- If purchasing or replacing scales, buy new scales that measure in, or can be locked to measure in, metric units only.
- Have charts that convert from kilograms (or grams for pediatrics) to pounds available near all scales, so that patients/ caregivers/parents can be told the weight in pounds, if requested.
- Ensure that electronic health record screen views, medication device screens (e.g., infusion pumps), printed patient information documents, and printed order and/or communication forms, list, or prompt for the patient’s weight in metric units only.
- Document the patient’s weight in metric units only in all electronic and written formats.
2024-2025 ISMP Targeted Medication Safety Best Practices for Hospitals
