Main Unit
Theory of Operation
1 - 10
1.3.6
Parameter modules
Multi-Parameter board
The multi-parameter board incorporates multiple parameters, such as ECG, RESP, DPM
SPO
2
, 2-channel IBP, TEMP, etc. Details include the following:
• The multi-parameter board employs a high-speed DSP, making digital filtering, arrhythmia
analysis, and ST analysis faster and more effective.
• The DSP is in charge of 3- and 5-lead ECG monitoring, arrhythmia and ST analysis, RESP
monitoring, and communicating with the CPU board.
• The multi-parameter board also employs an MCU, which supports 1-channel temperature
measurement, DPM SpO
2
, and 2-channel IBP measurement. The MCU transfers all the
measurement data to the DSP.
• Respiration rate is monitored using the impedance method and can only be measured
with two ECG leads.
• The multi-parameter board integrates the DPM SpO
2
circuit. If a monitor is configured
with an OEM SpO
2
module, then DPM SpO
2
functions are overridden.
CO
2
Module
• There are two types of CO
2
modules: DPM CO
2
and Microstream CO
2
.
• The DPM CO
2
module measures the CO
2
concentration using the NDIR technology. It
performs a zero calibration periodically to ensure accurate measurements for a long
period of time. An appropriate compensation can be applied according to the patient
environment, thus preventing measurements from being influenced by interfering gases.
• The Microstream CO
2
module ensures that measurements will not be affected by other
gases and the accuracy can be maintained without any gas compensation. Additionally,
the module has a very low sample flow rate, reducing its effect on the patient and the
environment to a minimum.
OEM SpO
2
Module
There are two types of OEM SpO
2
modules: Masimo-2013 SpO
2
module and Nellcor SpO
2
module.
An isolation power board is attached to each of them and used to isolate the DC power and
the UART signal of the OEM SpO
2
modules from other circuits in the main unit. The UART
signal comes from the CPU board and passes through the power management and interface
board.
