Evaluation of the Accuracy of Current Tubeless Pumps for Continuous Subcutaneous Insulin Infusion

Abstract

Background: Recently two new tubeless pumps for insulin therapy were introduced. They were tested for accuracy and occlusion detection and compared with the established patch pump Omnipod ® (OP). Methods: Using a modified setup for tubeless pumps based on IEC 60601-2-24, the basal rate and bolus delivery of the Accu-Chek ® Solo micropump system (ACS) and the A6 TouchCare ® System (A6) were measured with a microgravimetric method. Bolus sizes of 0.2, 1, and 10 U, and basal rates of 0.1 and 1 U/h were evaluated in nine repetitions. For each parameter, mean deviation and number of individual boluses or 1-h basal rate windows within ±15% from target were calculated. In addition, occlusion detection time at basal rates of 0.1 and 1 U/h was determined. Results: Mean deviation of boluses of different volumes in the pumps ranged from −3.3% to +4.0% and 40%–100% of individual boluses were within ±15% of the target. During basal rate delivery, 41% to 98% of 1-h windows were within ±15% of the target with a mean deviation between −8.9% and +4.8%. In general, considerable differences between pump models were observed and deviations decreased with increasing doses. In most parameters, ACS was more accurate, and A6 less accurate, than OP. Mean occlusion detection time ranged from ∼3 h to 7.5 h at 1 U/h and was >24 h or absent at 0.1 U/h. Conclusions: In this evaluation, significant differences between the tested tubeless pump models were observed that became most evident when regarding delivery errors over short time and small volumes.