Medical Applications User Guide (pdf) - Freescale Semiconductor
Medical Applications User Guide (pdf) - Freescale Semiconductor
Medical Applications User Guide (pdf) - Freescale Semiconductor
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12.2<br />
System Sensors<br />
Figure 12-1: Ventilation/Respiration General Block Diagram<br />
Ventilation/Respiration<br />
The signal that shows lung volume is a differential<br />
AIR O2 signal, but this is not the signal measured<br />
directly from the lungs. To get this signal, it is<br />
PWR<br />
PWR<br />
necessary to transduce the pressure to voltage.<br />
This is done by using a pneumotachometer<br />
that contains a pressure sensor.<br />
PWF<br />
Sensor<br />
Nebulizer<br />
Accumulator/<br />
Compressor<br />
Blender Display<br />
<strong>Freescale</strong> provides a variety of sensors that<br />
Pressure<br />
Sensor<br />
Volume<br />
Wireless<br />
Comm<br />
use integrated circuits for signal conditioning.<br />
This is an advantage because external<br />
components are not necessary. However, it<br />
Sensor<br />
Flow<br />
Sensor<br />
Power<br />
AMP<br />
MCU/MPU<br />
USB<br />
is necessary to check the resolution of the<br />
sensor and the ADC. If the resolution of the<br />
Management<br />
ADC is greater than the sensor, amplifying<br />
the signal is recommended. Some sensors<br />
provide differential outputs for when it is<br />
Alarm<br />
Keypad or<br />
Touch Screen<br />
necessary to pass the signal through an<br />
instrument amplifier. The sensor used is a<br />
differential pressure sensor that can accept<br />
two sources of pressure simultaneously. The<br />
output is proportional to the difference of<br />
the two sources. It is important to mention<br />
<strong>Freescale</strong> Technology Optional<br />
that the normal pipeline gas source of a<br />
Ventilation/Respiration<br />
hospital is 50 PSI, a measurement that<br />
Figure 12-2: Spirometer<br />
can be taken by <strong>Freescale</strong>’s pressure Figure 11-2: Spirometer<br />
sensors. <strong>Freescale</strong> pressure sensors include<br />
AIR O2 MPX2300DT1, MPX2301DT1, MPXC2011DT1,<br />
PWR<br />
PWR<br />
MPXC2012DT1, MPX2050 and MPX5050.<br />
12.3<br />
PWF<br />
Sensor<br />
MPX2300DT1<br />
Accumulator/<br />
Nebulizer MPX2301DT1<br />
Compressor<br />
MPXC2011DT1<br />
Blender Display<br />
Spirometer<br />
Spirometers measure static pulmonary<br />
Pressure<br />
Sensor<br />
Volume<br />
MPXC2012DT1<br />
MPX5050<br />
MPX2050<br />
Wireless<br />
Comm<br />
volumes, except the functional residual<br />
capacity (FRC) and total pulmonary capacity<br />
Sensor<br />
Flow<br />
Sensor<br />
AMP<br />
Amplification<br />
MCU/MPU<br />
USB<br />
(TPC). The measurement is done after a<br />
Power<br />
Circuit<br />
maximum inspiration that requires the patient<br />
to expel the entire volume of air that he or she<br />
Management<br />
can. The results are interpreted and compared<br />
with the values for age, height, sex and race<br />
of the patient. Due to variations among normal<br />
Alarm<br />
Keypad or<br />
Touch Screen<br />
individuals, normal values can fall between 80<br />
to 120 percent of the expected volume. Figure<br />
12-2 illustrates how to configure a spirometer<br />
using a pressure sensor. The next two figures<br />
observe the different volumes of lungs.<br />
<strong>Freescale</strong> Technology Optional<br />
Lung volume measurements include:<br />
• Tidal volume (TV)—The amount of gas<br />
inspired or expired with each breath (500 ml)<br />
Diagnostic and Therapy Devices<br />
freescale .com/medical 65
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