(664a) Advances in Control Algorithms for Blood Glucose Regulation in the Intensive Care Unit (ICU)

A remarkable study by Van den Berghe et al. (2001) demonstrated that maintaining blood glucose below 110mg/dl will dramatically reduce overall in-hospital mortality, bloodstream infection and acute renal failure in intensive care unit (ICU) patients. Most major hospitals, therefore, have a goal of tight glycemic control in the ICU. In this presentation, ICU blood glucose regulation algorithms are reviewed, analyzed, and compared using a three-state physiological model (Chase et al., 2006) for simulation studies based on 16 sets of model parameters (that is, a population of 16 distinct in silico subjects). The open-loop steady-state and dynamic behavior of the system is studied to assist controller design. Various control algorithms, including IMC-based PID, Columnar Insulin Dosing (CID), Glucose Regulation for Intensive Care Patients (GRIP), and Biostator II, are studied to understand the effect of tuning parameters and sample time on the control performance.

There are major limitations to the closed-loop performance for subjects that have extreme physiological parameters, particularly for the linear control algorithms. In this presentation we show the advantage of using ?human-friendly? identification techniques to develop models specific to each individual in the ICU, and then using model-based control strategies. We discuss the important effect of sample time and glucose sensor quality, since currently the nursing staff takes blood glucose samples at 1-4 hour intervals, using high quality laboratory instruments. Finally, we relate these results to on-going clinical studies in the closed-loop control of individuals with type 1 diabetes.

Keywords: ICU, IMC-based PID, CID, GRIP, Biostator II, blood glucose regulation

Literature Cited

Chase JG, Shaw GM, Wong XW, Lotz T, Lin J, Hann CE. Model-based glycemic control in critical care-A review of the state of the possible. Biomedical Signal Processing and Control. 2006;1(1):3-21.

Van Den Berghe G, Wouters P, Weekers F, Verwaest C, Bruyninckx F, Schetz M, Vlasselaers D, Ferdinande P, Lauwers P, Gouillon R. Intensive insulin therapy in critically ill patients. N Engl J. Med. 2001 Nov 8; 345 (19):1359-67.