Sources and magnitude of error in preparing morphine infusions for nurse-patient controlled analgesia in a UK paediatric hospital
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Background Administering nurse/patient controlled analgesia (N/PCA) to children requires complex dose calculations and multiple manipulations to prepare morphine solutions in 50 mL syringes for administration by continuous infusion with additional boluses. Objective To investigate current practice and accuracy during preparation of morphine N/PCA infusions in hospital theatres and wards at a UK children’s hospital. Methods Direct observation of infusion preparation methods and morphine concentration quantification using UV–Vis spectrophotometry. The British Pharmacopoeia specification for morphine sulphate injection drug content (±7.5 %) was used as a reference limit. Results Preparation of 153 morphine infusions for 128 paediatric patients was observed. Differences in preparation method were identified, with selection of inappropriate syringe size noted. Lack of appreciation of the existence of a volume overage (i.e. volume in excess of the nominal volume) in morphine ampoules was identified. Final volume of the infusion was greater than the target (50 mL) in 33.3 % of preparations. Of 78 infusions analysed, 61.5 % had a morphine concentration outside 92.5–107.5 % of label strength. Ten infusions deviated by more than 20 %, with one by 100 %. Conclusions Variation in morphine infusion preparation method was identified. Lack of appreciation of the volume overage in ampoules, volumetric accuracy of different syringe sizes and ability to perform large dilutions of small volumes were sources of inaccuracy in infusion concentration, resulting in patients receiving morphine doses higher or lower than prescribed.
KeywordsAnalgesia Children Medication Error Morphine Nurse Opioid intravenous infusions Preparation Paediatrics United Kingdom
Authors wish to thank HCPs participated, and the project steering group members, in particular, Dr Caroline Davies, Hazel Foale and Sara Arenas for helping in facilitating this study. We thank QC staff for undertaking morphine assay.
This project was funded by the Health Foundation (SHINE 2012 programme). The Health Foundation is an independent charity working to continuously improve quality of healthcare in UK.
Conflicts of interest
ANR was funded by the Health Foundation. Other authors declared no financial interests.
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