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3.1
NICO Model 7300 Non-Invasive Cardiac Output Monitor
3.2
Digital Board 2763
3.2.1
Rev 00
Theory of Operation
The NICO model 7300 monitor measures cardiac output based on changes in
respiratory CO
concentration caused by a brief period of rebreathing. The
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measurement of cardiac output is accomplished by interpreting data collected by
proprietary sensors that measure flow, airway pressure, and CO
then combining these signals to calculate CO
technique known as Fick partial rebreathing is applied to calculate cardiac output.
NICO can be used with mechanically ventilated patients in the operating room,
intensive care, or emergency departments.
Microprocessor
Refer to sheet 1 of the 2763-03 schematic.
The generation of the logic and control signals for the purpose of acquiring the raw
physiological parameters, and management of the data needed to produce an accurate
Non-Invasive Cardiac Output, are the responsibilities of microprocessor IC1. This
device, a Motorola MC68332, is a highly integrated 32-bit microcontroller that
combines high-performance data manipulation capabilities with powerful peripheral
subsystems. These subsystems include circuitry for timing generation, peripheral chip
selection and data control, interrupt generation, as well as synchronous and
asynchronous serial communication. Also included is a sophisticated timing co-
processor, the TPU (Time Processor Unit), that can generate complex timing
waveforms independent of the main processor. In general, the signals for subsystems
are functionally grouped into ports which can be independently programmed by
software to be a pre-defined port function or discrete I/O. Additionally, the functionality
for several ports (Ports C, E and F) can be pre-defined by the state of specific data bus
lines on system power-up. Included is a special "background mode" port that allows the
device to be externally controlled, facilitating system debugging and testing. Also
integrated on-chip are several activity monitors as well as a software watchdog to
ensure proper device and system operation. Refer to table 1.
Port
TPU
16 Channels
2
Defined Function
Timing Signal Generation
Table 1: CPU Port Functions
concentration, and
2
elimination. Using these variables, a
Functionality & Power-up Control
Each channel independently user
programmable as TPU function or as
Discrete I/O
Model 7300 Service Manual
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