The Glycostat system consists of a durable part and a consumable part.
The durable part consists of a photo detector and an electronic unit. The electronic unit takes care of all user interface, records all data, handles data input and output, handles calibration (once per 24 hours), handles alarms and settings, and has a touch screen display where trends can be read.
The consumable part consists of a reagent cassette, a satellite unit, and a microdialysis measurement probe. The microdialysis measurement probe is easily inserted into and remains in the distal lumen of a standard central venous catheter
The principle of operation is as follows:
· Glucose sampling – The glucose sample is collected intravenously utilizing the micro-dialysis catheter. The Glucose is recovered in the perfusate solution (saline) and transported to the sample manifold and µ-fluidic reaction chip.
· Enzymatic reaction – The collected glucose reacts with glucose oxidase and dissolved oxygen to form stoechiometric amounts of hydrogen peroxide.
· Detection – The formed hydrogen peroxide is detected optically by the chemiluminescence generated from the reaction between luminol, ferricyanide catalyst and hydrogen peroxide. The electronic signals generated by the satellite photo-sensor (optical detector) in physical contact with the satellite processing manifold (location of chemiluminescence reaction) are continuously processed by the stationary electronics unit (monitor) to display current glucose reading in a graphical and numerical format.
· Use – The device is calibrated regularly from readings of blood samples processed with an independent standard in-vitro glucose analyzer. Reagents and perfusion liquid are propelled within the closed system cassette and manifold components by means of constant pressure pumping mechanics housed within the monitor. Each cassette contains sufficient perfusion liquid and reagents for a continuous 3 day operational period.
· Algorithm – Glycostat has an advanced algorithm which continuously calculates the insulin rate needed in order to keep the blood glucose concentration of the ICU patient within the desired range. If the algorithm calculation shows that the insulin infusion rate needs to be changed Glycostat will send an alert to the ICU nurse and suggest the insulin infusion rate is changed accordingly.
· Closed Loop Operation – Glycostat is enabled to feed the information from the algorithm regarding needed changes of the insulin infusion rate directly to the insulin infusion pump so that no nurse intervention will be needed. In this way Glycostat will be automatically controlling the ICU patients blood glucose concentration without needed intervention from the ICU nurse. This is called closed loop control, or artificial pancreas operation.