Doctors and nurses estimation of the weight of patients: A preventable source of systematic error

Although accurate determination of body weight is important in the management of the poisoned patient, many patients have their weight estimated rather than formally measured.

To determine how good medical staff are at estimating patients*** body weights.

Medical staff were asked to estimate the weight of six patients on a poisons ward. Estimated and actual patient weights were statistically compared.

Medical staff produced a large range of estimated weights for all patients. Patient weight was incorrectly estimated by greater than 10% in 61% of individual estimations. There was poor statistical correlation between actual and estimated weight.

All patients administered medication based on body weight and those treated following an overdose of any substance should have formal body weight determined as part of their standard management.