A finite element model for insulin adsorption in ICU infusion sets

Insulin adsorption has been observed in ICU delivery lines, and is especially problematic in the delivery of insulin within the neonatal ICU. This paper presents a two state model with adsorptive loss described as a predator-prey term with parameters K_i and B_eq. This model is discretized to N sub volumes along the length of an infusion set. The model was found to converge to a solution for N>~100-150. The model was fit to literature data, and it was found that the total adsorptive capacity of a material (B_eq, U/m²) was hyperbolically related to flow rate. If the average rate constant K_i was used with the hyperbolic relationship, the model was able to describe adsorption dynamics at all 3 examined flow rates for a polyethylene line.