Miriam E. Tucker August 2008
In an article from Critical Endocrinology News, information is presented on the steps towards closing the loop in the Artificial Pancreas Project. The JDRF has been working to solve many issues which have been problematic to completing this project. These include adding an automated pump shut-off, having "hybrid" glucose cont
rol, the possible inclusion of glucogen, silico modeling and incorporating an in-hospital closed loop system.
The automated pump shut-off will control the information sent from the sensor to shut off insulin delivery; this whole process will help to prevent hypo/hyper glycemic levels in patients.
"Hybrid" glucose control refers to a new attempt at regulating infusion rates. Dr. Stuart Weinzimer of the department of pediatrics at Yale University and his associates found that the controlling algorithm was leaving significant postprandial excursions with the system because of delays in insulin absorption. Weinzimer and his associates proposed introducing small manual priming doses prior to meals during close looped control. The results were not quite what the researchers expected, but they are optimistic about the feasibility of the closed loop control with the interaction of manual doses. “Further refinements are necessary to accelerate insulin action and decay rates to minimize postprandial glycemic excursions and reduce late postprandial hypoglycemia,” said Weinzimer.
Inclusion of glucogen is a debatable area, but according to Edward Damiano, Ph.D, of the division of Biomedical Engineering at Boston University, the introduction of glucogen in a truly closed loop system is neccessary. “I’m pretty convinced that you need a counterregulatory hormone. In real life, tremendous precipitous drops in blood sugar can happen due to changes in insulin sensitivity in a very short space of time. ... There’s no way a machine can prevent something like that, that quickly. Glucagon works extremely fast,” he said.
Another topic, in silico modeling refers to computer simulation of patient and device variables. Typically, there is a need to study animals before humans, but this is costly and time consuming. These computer simulations can rapidly assess the feasibility of various algorithms for human trials and therfore save years of time which would have been spent on testing.
Finally, in-hospital closed loop systems could be very beneficial for hospitalized patients. It would help to take strain off of nursing staffs who cannot manage to closely monitor patients continuously. And since most initial clinical trials have taken place in hospital settings, it would not be an uncommon practice.
All in all, these topics are among the final obstacles and decisions which must be solved and determined for the completion of the closed loop system. Just a few steps now stand between us and a functional Artificial Pancreas.
http://www.jdrf.org/files/General_Files/APP/2008/Clinicalendocrinologynews_AP.pdf
In an article from Critical Endocrinology News, information is presented on the steps towards closing the loop in the Artificial Pancreas Project. The JDRF has been working to solve many issues which have been problematic to completing this project. These include adding an automated pump shut-off, having "hybrid" glucose cont
rol, the possible inclusion of glucogen, silico modeling and incorporating an in-hospital closed loop system.The automated pump shut-off will control the information sent from the sensor to shut off insulin delivery; this whole process will help to prevent hypo/hyper glycemic levels in patients.
"Hybrid" glucose control refers to a new attempt at regulating infusion rates. Dr. Stuart Weinzimer of the department of pediatrics at Yale University and his associates found that the controlling algorithm was leaving significant postprandial excursions with the system because of delays in insulin absorption. Weinzimer and his associates proposed introducing small manual priming doses prior to meals during close looped control. The results were not quite what the researchers expected, but they are optimistic about the feasibility of the closed loop control with the interaction of manual doses. “Further refinements are necessary to accelerate insulin action and decay rates to minimize postprandial glycemic excursions and reduce late postprandial hypoglycemia,” said Weinzimer.
Inclusion of glucogen is a debatable area, but according to Edward Damiano, Ph.D, of the division of Biomedical Engineering at Boston University, the introduction of glucogen in a truly closed loop system is neccessary. “I’m pretty convinced that you need a counterregulatory hormone. In real life, tremendous precipitous drops in blood sugar can happen due to changes in insulin sensitivity in a very short space of time. ... There’s no way a machine can prevent something like that, that quickly. Glucagon works extremely fast,” he said.
Another topic, in silico modeling refers to computer simulation of patient and device variables. Typically, there is a need to study animals before humans, but this is costly and time consuming. These computer simulations can rapidly assess the feasibility of various algorithms for human trials and therfore save years of time which would have been spent on testing.
Finally, in-hospital closed loop systems could be very beneficial for hospitalized patients. It would help to take strain off of nursing staffs who cannot manage to closely monitor patients continuously. And since most initial clinical trials have taken place in hospital settings, it would not be an uncommon practice.
All in all, these topics are among the final obstacles and decisions which must be solved and determined for the completion of the closed loop system. Just a few steps now stand between us and a functional Artificial Pancreas.
http://www.jdrf.org/files/General_Files/APP/2008/Clinicalendocrinologynews_AP.pdf
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