The skeleton ventilator is shown in Figure 3 connected to a Michigan Instruments calibrated test lung. The main components in the ventilator are the proportional flow control valve (PFCV), the exhalation valve, and the pressure sensor.

Figure 3 - Pneumatic Components Used to Create the Skeleton Ventilator

Electronic Development
We used a microcontroller board based on a Siemens C167 microprocessor, although any industry standard microcontroller can be used. The microcontroller executes 10 MIPS, has 16 channels of 10 bit A/D, and a high speed serial port. We then designed and built interface circuitry including: valve drivers, pressure transducer interface and calibration circuitry, and a PWM based current driver for the PFCV. Figure 5 shows the microcontroller board with two interface boards integrated together.

Figure 5 - Microcontroller (top right), Valve Drivers (top left), and Pressure Transducer with Interface Circuitry (bottom)

Test Setup Development
Along with the ventilator and electronic development, we borrowed a variety of test equipment from the University of Florida Department of Anesthesiology. Together we created a complete testbed for our ventilator control development.

Figure 6 - Block Diagram of Neural Ventilator Setup

Figure 6 shows the data flow diagram for the neural ventilator system. Figure 7 shows a picture of the test setup for the neural ventilator. At the left-center of the figure is a Michigan Instruments calibrated test lung. The test lung has a variety of controls and gauges used to setup various lung conditions. Although the test lung has two compartments/lungs, we only ventilate one lung since we can lump the characteristics of both lungs into a single lung. On the left side of the figure is an older commercial ventilator which we use to simulate spontaneous breathing. The commercial ventilator is connected to the second lung (left side) which has a lifting bar connected between it and the right hand lung (our test lung). When the commercial ventilator inflates the left lung, it pulls up the right lung simulating a negative pressure breath in the test lung. This particular commercial ventilator is setup to generate a sinusoidal waveform which is very similar to the waveform created by a spontaneously breathing patient.

On the center-right of Figure 7 is a laptop PC running NeuroSolutions and our custom OLE software. On the far right side is the power supply, ventilator pneumatics, and electronic interface hardware. This hardware is our ventilator and is used to ventilate the right lung of the test lung.

Figure 7 - Ventilator Test Setup. Shown from left to right: ventilator to simulate breathing, test lung, PC running NeuroSolutions, our ventilator pneumatics and interface circuitry.

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