Model based insulin absorption into intravenous infusion sets in adult and neonatal intensive care unit’s

Abstract

Abstract Introduction: While still a contentious topic, some studies suggest regulating blood glucose (BG) between 4.4 and 8.0 mmol/L improves clinical outcomes. Model based approaches have been successful at modulating BG in intensive care unit (ICU) setting using insulin. However, insulin absorption by infusion set materials may reduce the quality of control. Previous studies highlight the occurrence of significant absorption, but are highly variable in methodology and results. No study considers or accounts for all potential variables affecting insulin absorption by infusion tubing. This study will identify and model these variables to better understand and account for potential insulin losses. Modelling Methodology: The insulin absorption model developed is a compartment model based on conservation of mass. Literature data was collected and the model was validated based on fitting error. K1 and K2 are the absorption rates of insulin into the tubing and the rate of insulin release into free flow, respectively. K1 and K2 and were identified iteratively using Matlab to fit the model to literature data. Results and Discussion: The model fit the experimental data for PE and PVC tubes well, with a max percentage difference of 8.54% between the fitted and experimental data. The model was more inaccurate for PVC tubes than PE tubes. K1 values identified were similar magnitude for both materials, K2 was a similar magnitude for PVC, but not PE. Limited data from other studies meant they could not be used to test the model more completely. The assumption that the concentration of insulin in the syringe is what is specified could also be a source of variability. More experiments need to be carried out to make conclusions on K1 and K2, relative to specific materials, but this first model of this phenomenon is fundamentally sounds, justifying explicit validation testing.