Susceptibility of two different PCA pumps to inaccurate delivery associated with pole position at low flow-rates in a pediatric setting - an experimental study.

Purpose: Vertical displacement of infusion pumps used in patient-controlled analgesia can cause irregularities in drug delivery and is especially crucial at low flow rates, which are commonly used in pediatrics. There is only scarce data available regarding the extent of these inaccuracies. The current in vitro study therefore aimed at a comparison of the performance of two commonly used PCA pumps at different pole positions due to vertical displacement.

Methods: The Syramed^® µSP6000 Chroma syringe infusion pump featuring a stepper motor drive was compared to the CADD^®-Solis pump utilizing a linear peristaltic pump system at two different flow rates (0.3 ml/h and 1 ml/h) and three different levels of height (0, + 50 and - 50 cm). Flow patterns and delivered volumes were measured after every change in position and infusion boluses, retrograde aspiration volumes and zero-drug delivery time were calculated.

Results: The Syramed^® pump was more susceptible to vertical displacement than the CADD^®-Solis pump and showed overall greater inaccuracies in the delivered volumes as well as higher infusion boluses, retrograde aspiration volumes and zero-drug delivery time at both flow rates.

Conclusion: The observed differences between the pumps might be explained by the higher compliance of this syringe pump and the diverse working mechanisms. Overall, the CADD^®-Solis pump might be considered a preferable option for patient-controlled analgesia in children. It is nonetheless essential for medical staff to be aware of the effects of vertical displacement of PCA pumps and to minimize these displacements as much as possible.