Effect of Piperacillin/Tazobactam Solution Concentration on the Infusion Rate of Portable Elastomeric Pumps (‘EMPs’) in (HITH): A Retrospective Review of Administered and Residual Volumes

Importance Piperacillin/tazobactam solutions are frequently administered as 24-hour continuous intravenous infusions to patients in Hospital in the Home (HITH) programs and the accuracy of administration from elastomeric pumps (‘EMPs’) is important. Objective This study aimed to review the effect of piperacillin/tazobactam solution concentration on the rate of infusion from ‘EMPs’ to patients in the clinical HITH setting, by reviewing the volumes of residual and administered solution. Design This retrospective audit was conducted from 6/11/2021 to 14/6/2023 and the following information was collected for patients treated with piperacillin/tazobactam EMPs: patient details, treatment indication, EMP solution concentration, time of EMP attachment/detachment, volume of antibiotic solution remaining (if any), EMP type/brand, central line type, and central line issues (if any). Setting This study was conducted in the Central Coast Health District (CCLHD) HITH in New South Wales, Australia. Participants Patients treated with 24-hour continuous intravenous infusions of piperacillin/tazobactam via EMPs on the CCLHD HITH service. Results For all EMPs over all times, a median residual volume of 30mL (IQR: 0-50mL) was recorded (n=2152). Piperacillin/tazobactam 75mg/mL (18g/240mL) EMPs had a median residual volume of 50mL (IQR 20-70mL) when removed at ‘all times’ (n=170) and ‘=24 hours’ (n=184). Residual volumes >15% occurred 48% of the time when removed ‘=24 hours’ (n=325). Piperacillin/tazobactam 75mg/mL (18g/240mL) EMPs were significantly less likely to be removed (at ≥24 hours) with ≤15% residual volume compared to the piperacillin/tazobactam 37.5mg/mL (9g/240mL; p<0.001) or 56.25mg/mL (13.5g/240mL; p=0.008) EMPs. The mean percentage of piperacillin/tazobactam solution administered was significantly lower for the 75mg/mL EMP, with mean differences of -7.5% (95% CI [3.4, 11.6]; p<0.001) and -9.7% (95% CI [4.2, 15.2]; p=0.001) compared with the piperacillin tazobactam 56.25mg/mL (13.5g/240mL) and 37.5mg/mL (9g/240mL) EMPs respectively. Conclusion The piperacillin/tazobactam 75mg/mL (18g/240mL) solution significantly slowed the rate of infusion from the EMP compared to the piperacillin/tazobactam 37.5mg/mL (9g/240mL) and piperacillin/tazobactam 56.25mg/mL (13.5g/240mL) solutions. The appropriateness of piperacillin/tazobactam 75mg/mL (18g/240mL) EMPs in the clinical HITH setting should be carefully considered.