Non-flushing of IV administration sets: an under-recognised under-dosing risk.

Background: intravenous (IV) drugs are administered widely and under-dosing can result in therapy failure. The aim of this study was to quantify frequency, volume and dose of drug discarded within administration sets in the clinical setting.

Methods: residual volume for 24 different administration sets was measured under controlled conditions in a laboratory. Clinical assessment of current practice regarding post-infusion flushing occurred in 6 departments of one teaching hospital in the UK over 7 days. Details of drug last infused, (concentration, diluent and volume) and type and brand of administration set were collected.

Results: 74% of administration sets were not flushed. Non-flushing exceeded 90% and 61% for gravity and pump infusions respectively (p<0.001) in all areas excluding oncology. Oncology was the only area where flushing was standard practice for all infusions (p<0.001). Mean residual volume of the administration sets was 13.1 ml and 16.7 ml for gravity and pump sets respectively. Antibiotics were commonly infused and up to 21% of antibiotic dose was frequently discarded.

Conclusions: the findings suggest disposal of substantial volumes of drugs occurs frequently in general hospital areas. Without clear national and local policies this unrecognised under-dosing will continue.