Closed-loop Control Steady-State Basal Dosage Precision
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Solution Overview
Problem
Existing closed-loop control systems for insulin infusion are imprecise in steady-state conditions due to the inclusion of historical basal dosages in the calculation of unmetabolized insulin, leading to potential over-delivery and reduced precision in basal dosage determination.
Innovation Solution
The system determines the amount of unmetabolized therapeutic substance by excluding basal dosages from the calculation, allowing the insulin feedback term to have a zero value in steady-state conditions, and limits the integral component of the PID controller to a patient-specific maximum basal dosage, thereby improving precision and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If historical basal dosages are included in the calculation of unmetabolized insulin, then the closed-loop control system can maintain continuous insulin delivery, but the precision of basal dosage determination is reduced and over-delivery risk increases
Solution Approach 1:
The patent segments the insulin feedback calculation by excluding historical basal dosages from the unmetabolized insulin calculation, separating basal dosage determination from bolus dosage tracking. This allows the system to maintain continuous delivery reliability while improving basal dosage precision by only considering recent bolus dosages in the feedback term.
Solution Approach 2:
The patent extracts historical basal dosages from the insulin feedback calculation, removing the source of imprecision. By taking out the basal dosage component from the unmetabolized insulin calculation, the system eliminates the inflation effect that reduced measurement precision while preserving continuous delivery through separate basal control mechanisms.
2Reliability
If the insulin feedback term includes all historical dosages, then the closed-loop control system can account for cumulative insulin effects, but the system may cause over-delivery in steady-state conditions
Solution Approach 1:
The patent converts the potentially harmful effect of including basal dosages in feedback (which causes over-delivery) into a benefit by deliberately excluding them. This selective exclusion eliminates the harmful inflation effect while the system separately accounts for cumulative effects through dedicated basal dosage tracking and patient-specific maximum limits.
Solution Approach 2:
The patent applies preliminary anti-action by proactively excluding basal dosages from the insulin feedback term before they can cause over-delivery. This preventive measure stops the harmful cumulative effect from occurring in the first place, while the system maintains appropriate cumulative accounting through separate control mechanisms.
3Reliability
If the integral component of the PID controller is not limited, then the system can respond to sustained glucose deviations, but the system may deliver excessive basal dosage in steady-state conditions
Solution Approach 1:
The patent changes the parameter of the integral component by imposing a patient-specific maximum limit on accumulated insulin feedback. This parameter change allows the integral component to respond to sustained glucose deviations within safe boundaries, preventing excessive basal dosage delivery while maintaining the ability to correct persistent glycemic excursions.
Data Source
AI summary
Techniques disclosed herein relate to closed-loop control in steady-state conditions. In some embodiments, the techniques may involve determining an amount of unmetabolized therapeutic substance in a patient; determining, based on a measurement of a physiological condition of the patient and a target value for the physiological condition, a first amount or rate of a basal dosage for delivery to the patient; adjusting, based on the amount of unmetabolized therapeutic substance, the first amount or rate of the basal dosage to determine a second amount or rate of the basal dosage; and causing delivery of the second amount or rate of the basal dosage based on communicating the second amount or rate in a delivery command.