automating the Ex-VIVO HEART PERFUSIon SYSTEM
Project summary:
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A world class ex-vivo heart perfusion system was being developed at the Peter Munk Cardiac Center in Downton Toronto. Led by surgical director at the heart transplantation department, a large group of scientists worked with a variety of medical devices to keep the heart alive and stable outside the body. ​
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Biological and physical variables were being controlled by various independent medical devices to keep the heart alive. The scientists working on this unique system needed a way other than manually interacting with the devices to adjust parameters. A process that was extremely difficult, if not impossible, for a human. In part due to how fast a sudden change in a variable could affect the heart. The medical team needed the medical devices to be integrated in one automated system with an interface to control.
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Challenges:
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A big challenge was that the medical devices involved, were unique to the medical industry and often were manufactured by one company with proprietary design. Therefore engineering resources in terms of information on design and functionality of the devices were extremely limited.
Another major challenge was that these medical devices were not designed to communicate to common industrial controllers such as PLCs and data loggers. For example an important pressure transducer that was designed to connect to hemodynamic monitors used in hospitals, now needed to connect to a controller/PLC.
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Funding and time were both big issues, as each round of experiment that took place required booking an expensive operation room and organizing a large amount of logistics while complying with all hospital policies.
End result:
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Working with the medical scientists, focus was placed into dissecting and deciphering every medical equipment involved in the system to understand and "reverse engineer" their functionality.
Often these medical devices were taken apart, their front panel knobs and their potentiamteres were disintegrated so that they could be bypassed such that the master controller (PLC) can connect and takeover. In other cases pumps were disintegrated so that they could be controlled directly by the master controller (PLC).
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Once the ground work for the requirements of a controller was laid,
the hardware and PLC were selected, all the acquisition, installation and custom wiring between the hardware and all medical components were also completed. A 9" interface as well as the PLC were also programmed such that scientists could start controlling the medical devices through the master controller (PLC).
Last but not least, work started to decipher and reverse engineer the medical pressure transducers that were unique to the medical industry. As they also needed to connect to the master PLC, they had to be taken apart from the hemodynamic monitors. Their raw non-standard signal that was previously being fed to the hemodynamic monitors now needed to connect to the PLC. These raw low voltage signals needed to be amplified and processed such that their signal would become "PLC standard" (0-20mA, 0-5V, 0-10V, etc.)
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By use of our Tukoli Sensor Amplifiers the output signal of each pressure transducer was amplified and its noise removed. This allowed each pressure transducer that carried a pressure reading from a different part of the heart, to be properly connected to the PLC. These signals were then used in a feedback PID loop, that was also programmed and tuned in the PLC. The output of the PID loop was then used to control centrifugal pumps that were also unique to the medical industry. These pumps governed blood flow throughout the ex-vivo heart perfusion system.