Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue
  • A61B5/14532—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue for measuring glucose, e.g. by tissue impedance measurement
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/48—Other medical applications
  • A61B5/4836—Diagnosis combined with treatment in closed-loop systems or methods
  • A61B5/4839—Diagnosis combined with treatment in closed-loop systems or methods combined with drug delivery
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
  • A61B5/7271—Specific aspects of physiological measurement analysis
  • A61B5/7275—Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/168—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body
  • A61M5/172—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body electrical or electronic
  • A61M5/1723—Means for controlling media flow to the body or for metering media to the body, e.g. drip meters, counters ; Monitoring media flow to the body electrical or electronic using feedback of body parameters, e.g. blood-sugar, pressure
• • G—PHYSICS
  • G16—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR SPECIFIC APPLICATION FIELDS
  • G16H—HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA
  • G16H50/00—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
  • G16H50/30—ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics for calculating health indices; for individual health risk assessment
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
  • A61M5/00—Devices for bringing media into the body in a subcutaneous, intra-vascular or intramuscular way; Accessories therefor, e.g. filling or cleaning devices, arm-rests
  • A61M5/14—Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
  • A61M5/142—Pressure infusion, e.g. using pumps
  • A61M2005/14208—Pressure infusion, e.g. using pumps with a programmable infusion control system, characterised by the infusion program

Definitions

• the present invention is related to the field of medical systems and devices, and more specifically to medical systems and devices for controlling delivery of insulin (including analogs) to a subject to maintain euglycemia.
• Techniques are disclosed for adaptation of a glucose target (set-point) control variable in a glucose control system controlling delivery of insulin to a subject to maintain
• the term "insulin” encompasses all forms of insulin-like substances including natural human or animal insulin as well as synthetic insulin in any of a variety of forms (commonly referred to as an "insulin analogs").
• the glucose target adapts based on trends in actual glucose level (e.g., measured blood glucose in the subject), and/or computed doses of a counter-regulatory agent (e.g. glucagon or dextrose).
• a counter-regulatory agent e.g. glucagon or dextrose
• An adaptation region with upper and lower bounds for the glucose target may be imposed.
• the disclosed techniques can provide for robust and safe glucose level control.
• adaptation is based on computed doses of a counter-regulatory agent whether or not such agent is available or actually delivered to the subject, and may be used for example to adjust operation in a bihormonal control system, including during periods in which the counter-regulatory agent is not available for delivery, or in an insulin-only control system where (hypothetical) doses of a counter-regulatory agent are computed even it is absent.
• adaptation can be based on trends in glucose level (including emphasis on the extent and/or duration of low glucose levels or trends and/or the mean glucose) or a combination of trends in glucose level and computed doses of a counter-regulatory agent.
• Figure 1 is a block diagram of a blood glucose level control system
• Figure 2 is a block diagram of a blood glucose level controller
• Figure 3 is a block diagram of a corrective insulin controller
• Figure 4 is a flow diagram of high-level operation of the blood glucose level controller with respect to adjusting target glucose level
• Figures 5 and 6 are plots of results of simulations of the disclosed operation.
• a technique for automatically modulating the glucose target (set-point) used in an autonomous glucose-control system, whether employing the delivery of only insulin or the delivery of insulin as well as a counter-regulatory agent (e.g. glucagon or dextrose).
• the glucose target automatically adapts based on (a) the usage of a counter- regulatory agent, (b) the otherwise intended usage of a counter-regulatory agent had it been available (e.g. in insulin-only systems or in cases where the counter-regulatory agent or its delivery channel are temporarily unavailable), (c) trends in glucose level (including emphasis on the extent and/or duration of low glucose levels or trends and/or the mean glucose), or (d) any combination of these measures.
• the method may impose upper and/or lower bounds (static or dynamic) for the range over which the dynamic glucose target varies, and may co- exist with an option for a user to set a static target on a temporary (including isolated, recurring, or scheduled) basis.
• the method can be implemented within an autonomous glucose-control system or during periods of autonomous control in a semi-autonomous glucose-control system.
• An implementation example is in an automated insulin delivery system for ambulatory diabetes care.
• the glucose target is set to float dynamically online, between lower and upper bounds, depending on the degree of hypoglycemia or near- hypoglycemia that the system records in a moving receding time window.
• the degree or rate at which the glucose target adapts either upwards (towards its upper bound) or downwards (towards its lower bound) for a given degree of hypoglycemia or near-hypoglycemia may be controlled by a system setting or scaling factor.
• the glucose target may be set to float dynamically online, between lower and upper bounds, depending on the degree to which the mean glucose level in a moving receding time window is outside a targeted range of mean glucose level values that are desired. For example, the system dynamically raises the glucose target if the mean glucose level is below a certain threshold, below which there is no predicted benefit of additional glucose lowering, even if the target might not otherwise be raised based on the degree of hypoglycemia.
• the glucose target floats dynamically based on computed counter-regulatory doses over a moving receding time window.
• the method may work identically whether the system is functioning in a multi-hormonal configuration, where the counter-regulatory doses are computed and their delivery is performed or at least intended or attempted as part of the system operation, or in an insulin-only configuration, where the counter-regulatory doses are computed only hypothetically (as if a counter-regulatory agent were available) but are not actually delivered.
• the system automatically responds online by dynamically raising the glucose target.
• the degree or rate at which the glucose target floats upwards (departing from its lower bound and towards its upper bound) for a given amount of computed glucagon doses may be controlled by a system setting or scaling factor. For example, the higher the setting or scaling factor is, the more the glucose target will automatically rise for a given computed glucagon dosing amount.
• FIG 1 illustrates an automated control system 10 for regulating the blood glucose level of an animal subject (subject) 12, which may be a human.
• the subject 12 receives doses of insulin from one or more delivery devices 14, for example infusion pump(s) coupled by catheter(s) to a subcutaneous space of the subject 12.
• the delivery devices 14 may also deliver a counter-regulatory agent such as glucagon for control of blood glucose level under certain circumstances.
• the delivery devices 14 may be mechanically driven infusion mechanisms having dual cartridges for insulin and glucagon respectively.
• glucagon specifically, but it is to be understood that this is for convenience only and that other counter-regulatory agents may be used.
• the term "insulin” herein is to be understood as encompassing all forms of insulin-like substances including natural human or animal insulin as well as synthetic insulin in any of a variety of forms (commonly referred to as an "insulin analogs").
• a glucose sensor 16 is operatively coupled to the subject 12 to continually sample a glucose level of the subject 12. Sensing may be accomplished in a variety of ways.
• a controller 18 controls operation of the delivery device(s) 14 as a function of a glucose level signal 19 from the glucose sensor 16 and subject to programmed input parameters
• P ARAMS which may be provided by the patient/user.
• One externally provided parameter is a "setpoint" which establishes a target blood glucose level that the system 10 strives to maintain.
• the externally provided setpoint is referred to as a "raw” target glucose level signal, and identified as” r t ".
• the controller 18 operates based on a difference between a glucose level of the subject, as represented by the glucose level signal 19, and a target glucose level signal.
• the raw target glucose level signal r t is one input to the calculation of a variable target glucose level signal that is used in calculating corrective doses and that represents certain adaptation of the control operation to achieve certain results.
• the controller 18 is an electrical device with control circuitry that provides operating functionality as described herein.
• the controller 18 may be realized as a computerized device having computer instruction processing circuitry that executes one or more computer programs each including respective sets of computer instructions.
• the processing circuitry generally includes one or more processors along with memory and input/output circuitry coupled to the processor(s), where the memory stores computer program instructions and data and the input/output circuitry provides interface(s) to external devices such as the glucose sensor 16 and delivery device(s) 14.
• FIG. 2 shows the functional structure of the controller 18. It includes four separate controllers, namely a counter-regulatory (CTR-REG) controller 22, basal insulin controller 24, corrective insulin controller 26. and other controller(s) 28. Each controller may be realized as a computerized device executing respective computer programs (i.e., counter- regulatory program, basal insulin control program, corrective insulin control program, and other program(s) respectively).
• the counter-regulatory controller 22 generates a counter- regulatory dose control signal 34 provided to a counter-regulatory agent delivery device 14-1.
• Respective outputs 36 - 40 from the insulin controllers 24 -28 are combined to form an overall insulin dose control signal 42 provided to insulin delivery device(s) 14-2.
• the insulin delivery device(s) 14-2 may include devices tailored to deliver different types and/or quantities of insulin, with the exact configuration being known to and under the control of the controllers 24 - 28. For ease of description the collection of one or more insulin delivery devices 14-2 is referred below to in the singular as an insulin delivery device 14-2.
• inter-controller signals 44 enable communication of information from one controller, where the information is developed or generated, to another controller where the information is used for that controller's control function. Details are provided in the description of the control functions below.
• the corrective insulin controller 26 is the primary dynamic regulator of blood glucose level. It may use any of a variety of control schemes, including for example an MPC cost function in a manner described in US patent publication 2008/0208113 Al, the contents of which are incorporated by reference herein.
• a counter-regulatory agent may not be present or may not be used, in which case the counter-regulatory controller 22 may be absent.
• the counter-regulator controller 22 is still present and still generates values of doses of the counter-regulatory agent as information for use by the corrective insulin controller 26, even though no counter-regulatory agent is actually delivered.
• Figure 3 shows the controller 18 in additional detail, according to one embodiment. It includes the corrective controller 26 as well as target adaptation 48.
• the corrective controller 26 carries out the dynamic regulation of glucose level based on an input target glucose level shown as r t '. This dynamic value is generated by the target adaptation 48 partly on the basis of the input (generally fixed) target glucose level signal r t .
• the target adaptation 46 may be in a separate controller (e.g., one of the other controllers 28 of Figure 2).
• the dynamic target value may be used by only one or by multiple of the controllers within controller 18.
• Figure 4 illustrates certain operation pertaining to the controller 18 at a high level.
• an insulin dose control signal e.g., insulin dose control signal 38
• a measured glucose level signal e.g., glucose level signal 19
• a target glucose level signal e.g., glucose level signal 19
• corrective insulin doses based on the current (latest) target glucose level signal and variations of the measured glucose level signal occurring on the order of seconds to minutes. This is the function of the corrective control 46 of Figure 3.
• the corrective insulin controller 26 continually adjusts the target glucose level signal based on a calculated trend over a longer term of at least one of (a) values of the measured glucose level signal over the longer term and (b) values for computed doses of a counter-regulatory agent over the longer term. This is the function of the target adaptation 48 of Figure 3.
• r t to represent the input or "raw" target glucose level signal 19
• r t ' to represent the dynamic target glucose level signal that is used by the corrective controller 26 and counter-regulatory controller 22
• r t r t + f(G t ) + f ⁇ y t ) , r L ⁇ r t ⁇ r H , (1)
• G t are computed (intended) doses of a counter-regulatory agent (e.g. glucagon or glucose/dextrose)
• f(G t ) is some function of G t
• f(y t ) is some function of the glucose level y t
• r L and r H are predetermined lower and upper bounds on r t (which could themselves be dynamic).
• N defines the length of an interval over which accumulation (summation) of G t is performed
• S ' is a scaling or gain factor that defines the magnitudes of the offsets caused on r t ' by each contribution from G t included in the summation.
• S ' is a scaling or gain factor that defines the magnitudes of the offsets caused on r t ' by each contribution from y t included in the summation.
• the scaling or gain factor S ' could take on similar dependencies to those described for S°' .
• One practical implementation includes S ' being relatively low (or 0) for high values of y t and
• the computed quantity associated with a counter-regulatory agent may still be present even in systems where the counter-regulatory agent is completely absent, such as in insulin-only systems, by basing the implementation on a signal representing the intended counter-regulatory delivery had it been possible.
• the counter-regulatory agent is temporarily absent in a multi-hormonal system, such as during periods when the counter-regulatory agent or its delivery channel become unavailable or delivery of the counter-regulatory agent via its channel becomes not possible for whatever reasons.
• Figures 5 and 6 present results of simulations demonstrating the described method.
• Both plots show 48-hour simulations using the same recurring 24-hour continuous glucose monitoring (CGM) trace.
• CGM continuous glucose monitoring
• the first 24-hour period uses the same closed- loop algorithm without the implementation of the described method and using a constant glucose target r t of 100 mg/dl
• N will cover a longer term than the much shorter term (seconds to minutes) over which corrections could be made by the corrective insulin controller 26.
• the glucose target is plotted as a trace 60 spanning across the upper panel of the graph.
• Calculated insulin doses are shown at 62 as extending downward, while calculated glucagon doses are shown at 64 as extending upward. Both simulations assume a bihormonal configuration, although the implementation may be the same in the insulin-only configuration where the counter-regulatory agent is absent.
• Figure 5 presents results of a first simulation A, with S f y ' ⁇ O in Eq. (3) and with
• Figure 6 presents results of a second simulation B, with S ' ⁇ 0 in Eq. (2), and
• a glucose-control system employs an adaptive (dynamic) glucose target, including when the target is a single glucose level value or when it represents a range or interval of glucose levels.
• the adaptation of the glucose target may be autonomous in accordance with some mathematical formulation.
• the adaptive glucose target may be constrained to remain within predefined upper and lower bounds.
• the adaptation of the glucose target may be for the purpose of limiting the frequency, duration, or severity of low or near low glucose levels (such as below or near the low end of normal range) in order to provide safer and/or more stable glucose control.
• the adaptation of the glucose target may be for the purpose of maintaining an achieved mean glucose over a period of time to within a range of mean glucose values in order to minimize the long-term complications of diabetes, preferably avoiding a mean glucose level any lower than what is necessary to reduce long-term complications of diabetes.
• the adaptation of the glucose target may be for the purpose of modulating or limiting the actual delivery of or just computation of (hypothetical) doses of a counter-regulatory agent to insulin in order to provide safer and/or more stable glucose control. It may alternatively be for the purpose of modulating or limiting the delivery of insulin in order to provide safer and/or more stable glucose control.
• the adaptation of the glucose target may be based on the glucose levels in a past and/or receding time horizon, and it may be based on glucose levels that fall below a certain threshold in a past and/or receding time horizon.
• the adaptation of the glucose target may be based on actual delivery of or just computation of (hypothetical) doses of a counter-regulatory agent over a past and/or receding time horizon.
• the adaptation of the glucose target may be part of a glucose-control system that employs the delivery of only insulin, or alternatively employs the delivery of insulin and a counter-regulatory agent or agents, or alternatively that employs the delivery of insulin, a counter-regulatory agent or agents, and potentially other agents.
• the adaptation of the glucose target may coexist with an option for the user to set a static glucose target on a temporary (including isolated, recurring, or scheduled) basis.
• the glucose control system may be autonomous or semi-autonomous, and the adaptation of the glucose target may be different depending on whether the counter-regulatory agent is actually delivered or is computed but not actually delivered.
• the disclosed adaptation technique may be used in a variety of types of automatic glucose control system. In one example, it may be used in a glucose control system such as disclosed in US Patent 7,806,854 or PCT International Publication No. WO 2012/058694 A2.

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• 2016
  • 2016-08-08 EP EP21196917.5A patent/EP3957233A3/en not_active Withdrawn
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