Robust Modelling of the Glucose-Insulin System for Tight Glycaemic Control of Less Critical Care Patients
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
In the intensive care units, hyperglycaemia among the critically ill is associated with poor outcomes. Many studies have been done on managing hyperglycaemia in the critically ill. Patients in the ICU continue to benefit from the outcome of extensive studies including several randomized clinical trials on glycaemic control with intensive insulin therapy. Tight glycaemic control has now emerged as a major research focus in critical care due to its potential to simultaneously reduce both mortality and cost. Although the debate on tight glycaemic control is on going, managing glycaemic level in ICUs is gaining widespread acceptance as the adverse effects are well known. However, in the less acute wards, to date there have only been a single randomized, controlled study to examine the benefit of glycaemic control. Patients in the less acute wards do not receive the same level of care, as glycaemic control is not regarded as important and not a priority. Glycaemic goals in the less acute wards are often judged based on clinical experience rather than adhering to a standard protocol or a treatment guideline. It is important that patients in the less acute wards received the level of care as practised in the ICU. If hyperglycaemia worsens outcome in the ICU, a similar effect is seen within less acute wards. Hence, tight glycaemic control needs to be extended in the less critical setting as well. To support the establishment of a control protocol for patients in less acute wards, a method that has been successful in the critical care and can be adapted to the less acute wards, is the model based or model-derived control protocol. Model-based protocol can deliver a safe and effective patient-specific control, which means the glycaemic control protocol can be devised to each individual patient. Hence, a physiological model that represents the glucose-insulin regulatory system is presented in this thesis. The developed model, Intensive Control Insulin-Nutrition-Glucose (ICING) is based on the best aspects of two previous clinically-validated glucose-insulin models.