Kovatchev Boris, Patek Stephen, Dassau Eyal, Doyle Francis J, Magni Lalo, De Nicolao Giuseppe, Cobelli Claudio
Department of Psychiatry and Neurobehavioral Sciences and Department of Systems and Information Engineering, University of Virginia, Charlottesville, Virginia, USA.
J Diabetes Sci Technol. 2009 Sep 1;3(5):1058-65. doi: 10.1177/193229680900300509.
Closed-loop control of type 1 diabetes is receiving increasing attention due to advancement in glucose sensor and insulin pump technology. Here the function and structure of a class of control algorithms designed to exert control to range, defined as insulin treatment optimizing glycemia within a predefined target range by preventing extreme glucose fluctuations, are studied.
The main contribution of the article is definition of a modular architecture for control to range. Emphasis is on system specifications rather than algorithmic realization. The key system architecture elements are two interacting modules: range correction module, which assesses the risk for incipient hyper- or hypoglycemia and adjusts insulin rate accordingly, and safety supervision module, which assesses the risk for hypoglycemia and attenuates or discontinues insulin delivery when necessary. The novel engineering concept of range correction module is that algorithm action is relative to a nominal open-loop strategy-a predefined combination of basal rate and boluses believed to be optimal under nominal conditions.
A proof of concept of the feasibility of our control-to-range strategy is illustrated by using a prototypal implementation tested in silico on patient use cases. These functional and architectural distinctions provide several advantages, including (i) significant insulin delivery corrections are only made if relevant risks are detected; (ii) drawbacks of integral action are avoided, e.g., undershoots with consequent hypoglycemic risks; (iii) a simple linear model is sufficient and complex algorithmic constraints are replaced by safety supervision; and (iv) the nominal profile provides straightforward individualization for each patient.
We believe that the modular control-to-range system is the best approach to incremental development, regulatory approval, industrial deployment, and clinical acceptance of closed-loop control for diabetes.
由于葡萄糖传感器和胰岛素泵技术的进步，1型糖尿病的闭环控制受到越来越多的关注。本文研究了一类旨在实现血糖控制在一定范围内的控制算法的功能和结构，这类算法通过防止血糖剧烈波动，在预定义的目标范围内优化胰岛素治疗以控制血糖。
本文的主要贡献是定义了一种用于血糖控制在一定范围内的模块化架构。重点在于系统规范而非算法实现。关键的系统架构元素是两个相互作用的模块：范围校正模块，其评估早期高血糖或低血糖的风险并相应调整胰岛素输注速率；以及安全监督模块，其评估低血糖风险并在必要时减少或停止胰岛素输送。范围校正模块的新颖工程概念是算法动作相对于名义开环策略——一种在名义条件下被认为是最优的基础输注速率和大剂量胰岛素的预定义组合。
通过在计算机上对患者用例进行测试的原型实现，展示了我们的血糖控制在一定范围内策略可行性的概念验证。这些功能和架构上的区别提供了几个优点，包括：（i）仅在检测到相关风险时才进行显著的胰岛素输送校正；（ii）避免了积分作用的缺点，例如因低血糖风险导致的血糖过低；（iii）一个简单的线性模型就足够了，复杂的算法约束被安全监督所取代；（iv）名义曲线为每个患者提供了直接的个性化方案。
我们认为，模块化的血糖控制在一定范围内系统是糖尿病闭环控制的增量开发、监管批准、工业部署和临床接受的最佳方法。
