Implantable Emergency Hypoglycemia Treatment Device

The Glucachute An Implantable Emergency Hypoglycemia Treatment Device Matthew DeNardo and Jordan Jacobs May 1, 2009

Background This invention relates to treatment for persons with diabetes mellitus type 1, specifically to improving treatment options for those persons experiencing severe acute hypoglycemia (low levels of blood glucose). Diabetes is a metabolic disorder that results in high blood glucose levels. Typical treatment for diabetes involves administration of insulin, a hormone that triggers absorption of glucose in the blood. Insulin is usually injected into the body or delivered via a pump. Incorrect insulin dosage can trigger hypoglycemia and can further lead to seizures, coma, and death. Diabetics need to be aware of their blood sugar levels and there are many monitors available to accomplish this task. The typical monitor requires a blood sample on a test strip. Continuous glucose monitoring products, such as the Medtronic MiniMed Paradigm or the FreeStyle Navigator have been introduced more recently. The invention requires a continuous glucose monitor (CGM) to govern treatment and requires a means of communication between the CGM and the device. Wireless communication between a CGM and an insulin pump has already been used as a method of treating diabetes (also by Medtronic). Diabetics experiencing severe hypoglycemia require immediate treatment. Intravenous administration of dextrose is a treatment that has been used in the past. However, it is difficult for nontrained personnel to perform this task. More recently, “rescue kits” from manufacturers such as Eli Lilly and Company have been furnished to provide glucagon injections to persons suffering from severe hypoglycemia. These kits can be used by laypeople without prior training as the drug can be absorbed via muscle tissue. The problem with performing any hypoglycemia treatment is that the patient must either be conscious or someone else must be present and aware of the situation to administer care. The invention described herein provides a means of automatically delivering treatment to a person suffering from severe hypoglycemia. To the best of our knowledge and the extent of our literature and patent searches, no device for hypoglycemia treatment has been developed that can deliver treatment without user interaction.

Summary The invention, an implantable hypoglycemia treatment device, works in tandem with existing CGM technology. Both the device and the CGM are implanted and communicate wirelessly with an external display monitor and data collection system. The linking of these items facilitates the delivery of hypoglycemia treatment. CGMs already feature alarms that are activated based on blood glucose measurements. The device requires a simple modification to existing CGM software so that a severe hypoglycemic condition is not only signaled by an alarm, but that it can also activate the implanted device and signal it to deliver treatment. When an alarm is triggered, signaling hypoglycemia, the user, caretaker, or bystander requires sufficient time to respond and deliver treatment. Since the user may Matthew DeNardo and Jordan Jacobs

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have mitigated this condition by responding to an earlier alarm by consuming glucose-containing carbohydrates or by receiving an injection of dextrose or glucagon, it may be beneficial to have some elapsed time before the device automatically takes action. This elapsed time may be displayed on the external monitor as a countdown timer. If the user or other person has mitigated the hypoglycemia, the user should act to prevent the automatic treatment delivery. On the other hand, if the user is unconscious and alone, the timer will expire and the device will deliver treatment automatically.

Detailed Description The device has several embodiments and encompasses single and multiple-use paradigms. In the single-use device, the liquid portion of the treatment (e.g. dextrose or sterile diluting solution) is stored in a reservoir. The reservoir may be lined with a leak-proof material. In loading the liquid into the chamber, mechanical work is done to increase the chamber volume to accommodate the liquid. The energy used for displacement is stored as mechanical potential energy, which provides a force that attempts to compress the reservoir’s contents. The device’s reservoir has a single outlet that is controlled by a valve. The valve is of the normally closed type. The valve opens in response to a signal sent by the external monitor when the time to respond to a hypoglycemic event has elapsed. In opening the valve, the stored mechanical energy is used to displace the contents of the reservoir. In an embodiment where the treatment is solely liquid (e.g. dextrose), the reservoir outlet valve leads to the body. The fluid may be deposited directly at the site or delivered to another site via a tube. In an embodiment where the treatment is a solution (e.g. sterile diluting solution and freeze-dried glucagon), the reservoir outlet valve leads to a mixing chamber. In the mixing chamber, several liquids or liquids and solids are combined to produce a solution. The outlet of the mixing chamber leads to the body. In the multiple-use device, the reservoir described above also has an inlet that can be accessed from outside of the body. An embodiment of this concept is to use a self-healing compressed silicone septum that can be penetrated with a non-coring needle. This method is used to access the reservoir in vascular ports. An empty reservoir is refillable by injecting the liquid component of the treatment through the silicone septum. Adding fluid to the reservoir, driven by the syringe pressure, increases the chamber volume, performing mechanical work in the fashion described above. The reservoir outlet is controlled with a valve, also as described above. As before, in an embodiment where the treatment is solely liquid (e.g. dextrose), the reservoir outlet valve leads to the body. The fluid may be deposited directly at the site or delivered to another site via a tube. In an embodiment of a multi-use device where the treatment is a multi-liquid solution, multiple chambers in series keep the components separate. The chamber farthest from the outlet is preloaded, as described earlier. Subsequent chambers store the other liquid components until mixed. The outlet to the body is as previously described. In an embodiment of a multi-use device where the treatment consists of a liquid that dissolves at least one solid component (such as a powder), the liquid chamber is refillable and can be pressurized as described above. If it is possible to also refill the solid container percutaneously, then a second septum to access that chamber is used. Alternately, if the solid portion must be inserted before the device is implanted, a different approach is considered. The outlet path of the liquid chamber, downstream of the valve or as part of the valve, also Matthew DeNardo and Jordan Jacobs

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contains a mechanism for selecting one of several paths where the solid component is stored. The liquid and solid components feed into a mixing chamber as described above, and then the solution exits the device into the body. All embodiments require a power supply to operate the device. The power requirements are due to the operation of the wireless communication module (primary) and the mechanical operation of any of the components governing fluid flow (secondary). The power supply may be augmented with existing technology that uses energy generated by the patient’s motion to extend the life of the device.

Operation The envisioned usage for an embodiment of the device is as follows: A multi-use device (Figure 1) that relies on a sterile diluting solution and freeze-dried glucagon powder is unpackaged in a sterile operating field. The powder has been pre-loaded into the device. The implanting surgeon powers up the device, which performs a self-test and confirms that a communication link with its external monitor is established. The surgeon then attaches a syringe to a non-coring needle and loads it with the sterile diluting solution. The needle is inserted through the septum (Figure 1) and the liquid reservoir (Figure 3) is filled, thereby pressurizing it by storing mechanical energy in a spring (Figure 3). The device is then implanted in the abdomen along with a CGM (existing technology, not shown) that provides the external monitor (existing technology, not shown) with the data needed to detect and activate treatment for severe hypoglycemia. The surgeon places the device and concludes the procedure. When a severe hypoglycemic event occurs as detected by the CGM and reported by the monitor, the monitor sounds an alarm to alert the user and others nearby that the user needs treatment. In addition, the monitor alerts local emergency services of the patient’s location and condition. A timer begins counting down the time to automatically delivering treatment. The monitor also alerts anyone who may provide manual treatment to deactivate the timer with a button press prior to performing an injection. If the timer expires, then the monitor wirelessly sends a signal to the implanted device that opens the valve to the fluid chamber. The control valve (Figure 3) opens and selects one of the outlet paths and the diluting solution flows out of the reservoir to a mixing chamber (Figure 3). The chamber is pre-loaded with the freeze-dried glucagon powder, which dissolves when mixed with the solvent. As the pressure builds in the mixing chamber, the outlet valve opens (Figure 4) and allows the solution to enter the body. The external monitor then alerts anyone nearby that the user has already received treatment and that emergency medical attention is necessary. After receiving care, the user or a medical professional may reset the device by injecting a volume of sterile diluting solution to refill the reservoir. The act of doing so repressurizes the chamber and primes the control valve so it is ready to switch to the next available fluid path that contains a dose of the glucagon powder. Via the monitor, the system is capable of reporting how many doses remain. Once all of the doses have been consumed, the user is alerted of this status and is advised to see their medical professional.

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Figures Note: figures do not display the battery power supply, wireless communication module and other electronics, or the wireless antenna. The battery and electronic circuitry are both intended to be flat, rectangular items that can fit above and below the reservoir. The antenna is L-shaped and is intended to fit along the inner perimeter of the case.

Figure 1: The device features smooth outer contours and a septum on the top surface.

Figure 2: A glimpse of the assembled components.

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Figure 3: The components are identified. The reservoir is shown full, with the piston fully compressing the spring. The mixing chambers each hold a dose of freeze-dried glucagon powder.

Figure 4: Burst valves seal off the mixing chambers. Notice that the valves are scored to allow each one to split open under pressure.

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