We learned from users that the readout of a syringe pump shows the set point flow but it gives no feedback on the actual flow. Because of this lack of feedback on the actual flow being delivered, it is an area that should require regular accuracy checks. A regular programme of checks at a pre-determined flow rate or range is essential for ensuring that the delivery of fluid from the pump matches the expectations of the user. This is also an excellent opportunity to data log the performance of the pump for future reference and assists management purposes.
Moreover, we learned from medical engineering groups that there are currently two main calibrating techniques available for infusion pumps;
Volumetric measuring principle
The first uses volumetric measuring principles. This method usually needs a significant flow rate and minimum volume for achieving a reasonable accuracy within an acceptable period of time. This limits the ability to quickly check syringe pumps at the lowest flow rates and in critical applications. This creates a potentially inaccurate and time consuming calibration process.
Distance measuring principle
The second technique is to measure distance that the plunger travels over a pre-determined period of time and use that figure to extrapolate a figure for accept/reject. This technique is usually determined by the manufacturers of the instruments and carries with it a high degree of inaccuracy when adding together the manual method of measuring, the inaccuracy of the ruler and the cross sectional area of the plunger.
Both of the above methods lack information of the exact volumetric rate distribution over time.
Improving response time and accuracy of infusion pump calibrations
Recognizing some of the flaws in the techniques above, and having talked to several professional working groups that use syringe pump calibration systems, we were excited to begin new research In these studies we test new sensor technology and techniques that could benefit the response time and accuracy of infusion pump calibrations.