System and method for switching between closed loop and open loop control of an ambulatory infusion pump

Inventors

Rosinko, Michael J.

Assignees

Tandem Diabetes Care Inc

Abstract

An infusion pump system providing therapy to a patient in a closed-loop or semi-closed loop mode can safely automatically revert to open-loop therapy. The system stores a default open-loop basal rate profile in memory. The system also continually tracks the insulin on board for the patient over a plurality of closed-loop therapy intervals. When an error or event occurs requiring reversion to open-loop therapy, the system automatically provides therapy according to the open-loop basal rate profile and the tracked insulin on board amount.

Core Innovation

An ambulatory infusion pump-based artificial pancreas system provides diabetes therapy by delivering an infusion medicament in a closed-loop mode in which therapy parameters are automatically determined and medicament is automatically delivered based at least in part on information from a continuous glucose monitoring system. During the closed-loop mode, the system tracks an amount of insulin on board in the patient while automatic therapy is delivered according to the therapy parameters.

The system determines that the closed-loop mode should be terminated or exited when a CGM-related error/event is detected, including calibration, sensor failure, expiration, and loss of signal. In response to termination or exiting, CGM-based dosing is stopped and the infusion pump begins delivering medicament according to an open-loop basal rate profile in amounts according to the open-loop basal rate profile and the amount of insulin on board in the patient.

The system stores a default open-loop basal rate profile and can optionally update the open-loop basal rate profile between closed-loop intervals. The system continually tracks insulin on board across closed-loop intervals by accounting for insulin delivered relative to insulin pharmacokinetic decay and by using an approach based on insulin delivered during a time interval versus insulin expected from an open-loop basal profile over the same time interval.

Claims Coverage

The independent claims cover three method aspects: closed-loop automatic therapy with insulin-on-board tracking and switching to open-loop basal delivery upon termination; CGM-information-driven automatic therapy with insulin-on-board tracking and automatic cessation followed by open-loop basal delivery; and closed-loop therapy based on estimated blood glucose levels with insulin-on-board tracking and exiting to open-loop basal delivery. Across these independent claims, the core inventive elements include termination or exiting criteria tied to CGM-related errors or events and an open-loop basal rate response conditioned on insulin on board.

Collectively, the independent claims require automatic closed-loop CGM-based or estimated glucose-level-based medicament delivery with insulin-on-board tracking, followed by a termination or exiting decision and a switch to open-loop basal rate profile delivery conditioned on the tracked insulin on board.

Stated Advantages

Documented Applications