Improving dosing of gentamicin in the obese patient: a 3-cycle drug chart and case note audit

OBJECTIVES: To assess the use of an electronic dose calculator to improve accuracy in the use of a complex Gentamicin prescription policy and assess turnaround time of blood sampling to dose delivery in an NHS hospital. DESIGN: Retrospective review of drug chart, case notes and hospital antibiotic database. SETTING: University Hospitals Bristol, UK PARTICIPANTS: Patients receiving once daily intravenous gentamicin using the trust protocol, during the same time window for 3 consecutive years. MAIN OUTCOME MEASURES: i) Accuracy of dose and frequency prescription of Gentamicin. ii) Time frame for measurement of serum Gentamicin levels. RESULTS: Following the introduction of the online calculator, prescribing errors in obese patients dropped from 43% to 20%, a similar level as in non-obese patients. Errors in frequency calculations dropped from 12.8% to 4%. On average, drug doses could be administered within 2.5 hours of a blood sample being taken. CONCLUSIONS: Online tools can be used to improve prescribing for the complex dosing policies that will increasingly been required to tailor prescribing in obese patients. Serum gentamicin levels can be measured within a 2.5 hour time frame in the environment of an NHS hospital.