CARA Infusion Pump Project

SUNY at Stony Brook Computer Science Department

Contact: Prof. Eugene W. Stark

CARA (Computer-Assisted Resuscitation Algorithm) is a software system that provides closed-loop control to a high-output infusion pump. The system is intended to infuse fluids to resuscitate patients who are in danger of developing hypotension; for example, due to injuries sustained in a battlefield situation. The CARA software is designed to operate automatically, thereby minimizing the need for attention by medical personnel. The actual CARA system implementation is being developed by Walter Reed Army Institute of Research and their contractors. The simulation described below, developed in the Computer Science Department at the State University of New York at Stony Brook, has been constructed as part of research in formal methods sponsored by the Army Research Office (ARO) under grants ARO DAAD190110003 and ARO DAAD190110019.

The following items are currently available from this page:

The CARA simulation applet consists of two parts: the formal CARA model and the GUI code. Since it is our intention to use the formal CARA model as a reference model for formal verification experiments, this part has been written in a very stylized subset of Java which we expect will be easier to transfer to various verification tools. It is our intention to construct a faithful reference model of the CARA system which covers as many aspects of the system operation as possible. The GUI code is not part of the formal model, and in fact it is completely separate and decoupled from the formal model. The GUI performs its display functions by "peeking" at the model's state variables periodically and using that information to keep the screen up-to-date.

To run the applet, click on the link above. You will need Java Plug-in for your browser in order to run the applet. If you are using Internet Explorer or Netscape Navigator and you do not have Java Plug-in, you will be offered an opportunity to download it.

Once the applet has loaded, you will be presented with a display panel. The upper portions of the panel constitute the "Caregiver Console", and are intended to be a rendition of the information the real CARA system would display to the medical caregiver. The bottom portion of the panel is labeled "Simulation Internals". The various tabs on this panel give you the opportunity to view various state variable of the modules in the simulation and to influence the progress of the simulation to some extent.

The applet starts with the simulation in the paused mode. To run the simulation, click on the "Pause" button under the "Simulation Control" tab. The simulation can be run faster than real time by entering a value less than 1 into the "Time Scale" field. The "CARA Log" tab is intended to show a rendition of what would go into the actual CARA system log. The "Trace" tab is a much more detailed log of simulation internal events which is used for debugging and validating the model.

To make the simulation interesting, the modules that simulate external devices ("Pump", "Cuff Source", "Arterial Source", and "Pulse Wave Source") will undergo random failures and recoveries governed by simple two-state Markov chains. You can influence the failure state by clicking on some of the indicators on these tabs. For example, under the "Pump" tab, you can click on the "CONT", "OCC", and "Air OK" indicators to force a failure or recovery.

Last modified: Tue Jul 20 09:20:35 EDT 2004