Automatic closed-loop control adjustments and infusion systems incorporating same
View Patent ↗Infusion systems, infusion devices, and related operating methods are provided. An exemplary method of operating an infusion device capable of delivering fluid to a user involves identifying a condition of the user that is likely to influence a response to the fluid in the body of the user and classifying the condition as a first type of a plurality of types of conditions. After classifying the condition as the first type, the method continues by adjusting control information for operating the infusion device based on the first type and operating the infusion device to deliver the fluid to the user in accordance with the adjusted control information.
1. An infusion system comprising:
a motor operable to deliver fluid to a user, delivery of the fluid influencing a first condition of the user;
a sensing arrangement to obtain a measured value indicative of the first condition of the user;
a heart rate sensing arrangement to obtain heart rate measurement data for the user; and
a control system coupled to the motor, the heart rate sensing arrangement, and the sensing arrangement to:
determine a heart rate variability metric for the user based on a spectral analysis of the heart rate measurement data;
detect a second condition of the user that is likely to influence a response to the fluid in a body of the user based on the heart rate measurement data when a measured heart rate for the user is greater than a first threshold value and the heart rate variability metric is less than a second threshold value;
classify the second condition as exercise; and
after classifying the second condition as exercise:
adjust control information for operating the motor, resulting in adjusted control information; and
operate the motor to deliver the fluid to the user based at least in part on the adjusted control information and a difference between a target value for the first condition of the user and the measured value, wherein:
the adjusted control information comprises a decreased gain coefficient; and
the control system determines the decreased gain coefficient by estimating an amount of energy expenditure during the exercise, calculating a change in glycemic level for the user based on the amount of energy expenditure, determining an equivalent insulin amount based on the change in glycemic level, and determining an adjusted proportional gain coefficient based on a first difference between a daily insulin requirement for the user and the equivalent insulin amount.
2. The infusion system of claim 1 , wherein the control system operates the motor to deliver the fluid to the user based at least in part on the adjusted control information by determining a delivery command using the decreased gain coefficient and operating the motor in accordance with the delivery command.
3. The infusion system of claim 2 , wherein the adjusted control information further comprises an increased delivery limit.
4. The infusion system of claim 1 , further comprising an acceleration sensing arrangement to obtain acceleration measurement data for the user, wherein the control system is coupled to the acceleration sensing arrangement to:
determine an activity metric for the user based on the acceleration measurement data;
classify the second condition as exercise when the activity metric is greater than an exercise threshold value; and
classify the second condition as stress when the activity metric is less than the exercise threshold value.
5. The infusion system of claim 4 , wherein in response to classifying the second condition as exercise, the control system is configured to:
adjust the control information by decreasing a gain coefficient value; and
operate the motor by:
applying the gain coefficient value to the difference between the target value and the measured value to obtain a delivery command; and
operating the motor in accordance with the delivery command.
6. The infusion system of claim 4 , wherein in response to classifying the second condition as stress, the control system is configured to:
adjust the control information by increasing a gain coefficient value; and
operate the motor by:
applying the gain coefficient value to the difference between the target value and the measured value to obtain a delivery command; and
operating the motor in accordance with the delivery command.
7. The infusion system of claim 1 , wherein the control system operates the motor to deliver the fluid to the user based at least in part on the adjusted control information by:
determining a delivery command by applying the adjusted proportional gain coefficient to the difference between the target value for the first condition of the user and the measured value; and
operating the motor in accordance with the delivery command.
8. The infusion system of claim 1 , wherein the control system operates the motor by applying the adjusted control information to the difference to produce a delivery command and operating the motor in accordance with the delivery command to deliver the fluid to the user.
9. The infusion system of claim 1 , wherein:
the fluid comprises insulin; and
the second condition comprises an insulin sensitivity condition.
10. An infusion system comprising:
a motor operable to deliver fluid to a user, delivery of the fluid influencing a first condition of the user;
a sensing arrangement to obtain a measured value indicative of the first condition of the user;
a heart rate sensing arrangement to obtain heart rate measurement data for the user; and
a control system coupled to the motor, the heart rate sensing arrangement, and the sensing arrangement to:
determine a heart rate variability metric for the user based on a spectral analysis of the heart rate measurement data;
detect a second condition of the user that is likely to influence a response to the fluid in a body of the user based on the heart rate measurement data when a measured heart rate for the user is greater than a first threshold value and the heart rate variability metric is less than a second threshold value;
classify the second condition as stress; and
after classifying the second condition as stress:
adjust control information for operating the motor, resulting in adjusted control information; and
operate the motor to deliver the fluid to the user based at least in part on the adjusted control information and a difference between a target value for the first condition of the user and the measured value, wherein:
the adjusted control information comprises an increased gain coefficient; and
the control system determines the increased gain coefficient by estimating a change in glycemic level for the user based at least in part on an intensity of the stress, determining an equivalent insulin amount based on the change in glycemic level, and determining an adjusted proportional gain coefficient based on a first difference between a daily insulin requirement for the user and the equivalent insulin amount.
11. The infusion system of claim 10 , wherein the control system operates the motor to deliver the fluid to the user based at least in part on the adjusted control information by determining a delivery command using the increased gain coefficient and operating the motor in accordance with the delivery command.
12. The infusion system of claim 11 , wherein the adjusted control information further comprises a decreased delivery limit.
13. The infusion system of claim 10 , wherein the control system operates the motor to deliver the fluid to the user based at least in part on the adjusted control information by:
determining a delivery command by applying the adjusted proportional gain coefficient to the difference between the target value for the first condition of the user and the measured value; and
operating the motor in accordance with the delivery command.
14. An infusion system comprising:
a motor operable to deliver fluid to a user, delivery of the fluid influencing a first condition of the user;
a sensing arrangement to obtain a measured value indicative of the first condition of the user; and
a control system coupled to the motor and the sensing arrangement to identify a second condition of the user that is likely to influence a response to the fluid in a body of the user, classify the second condition as exercise, and after classifying the second condition as exercise:
estimate an amount of energy expenditure during the exercise;
calculate a change in glycemic level for the user based on the amount of energy expenditure;
determine an equivalent insulin amount based on the change in glycemic level;
determine a decreased proportional gain coefficient based on a first difference between a daily insulin requirement for the user and the equivalent insulin amount; and
operate the motor to deliver the fluid to the user based at least in part on the decreased proportional gain coefficient and a difference between a target value for the first condition of the user and the measured value.
15. An infusion system comprising:
a motor operable to deliver fluid to a user, delivery of the fluid influencing a first condition of the user;
a sensing arrangement to obtain a measured value indicative of the first condition of the user; and
a control system coupled to the motor and the sensing arrangement to identify a second condition of the user that is likely to influence a response to the fluid in a body of the user, classify the second condition as stress, and after classifying the second condition as stress:
estimate a change in glycemic level for the user based at least in part on an intensity of the stress;
determine an equivalent insulin amount based on the change in glycemic level;
determine an increased proportional gain coefficient based on a first difference between a daily insulin requirement for the user and the equivalent insulin amount; and
operate the motor to deliver the fluid to the user based at least in part on the increased proportional gain coefficient and a difference between a target value for the first condition of the user and the measured value.