Datex-Ohmeda S/5 monitors
Document No. 800 1008-2
10
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Applying a constant current through the resistor and measuring the voltage that is generated
across it.
In Datex-Ohmeda modules the two methods are combined in a form of a voltage divider. The NTC-
resistor is connected in series with a normal resistor and a constant voltage is applied across them.
The temperature dependent voltage can be detected at the junction of the resistors, thus producing
the temperature signal from the patient. The signal is amplified by analog amplifiers and further
processed by digital electronics.
2.1.5
Invasive blood pressure
To measure invasive blood pressure, a catheter is inserted into an artery or vein. The invasive
pressure setup, consisting of connecting tubing, pressure transducer, an intravenous bag of normal
saline all connected together by stopcocks, is attached to the catheter. The transducer is placed at
the same level with the heart, and is electrically zeroed.
The transducer is a piezo-resistive device that converts the pressure signal to a voltage. The monitor
interprets the voltage signal so that pressure data and pressure waveforms can be displayed.
2.1.6
Respiration
Impedance respiration is measured across the thorax between ECG electrodes. The signal of the
respiration is made by supplying current between electrodes and by measuring the differential
current from the electrodes. The signal measured is the impedance change caused by breathing.
From these impedance changes, respiration rate is calculated, and respiration waveform is
displayed on the screen.
2.2
Main components
2.2.1
M-ESTPR/-ETPR/-ESTR modules
Figure 3
Front panel of M-ESTPR
The
M-ESTPR, M-ETPR, and M-ESTR
modules
contain two main PC boards, the STP board and the
ECG board. They work independently. Both of them have their own processor and software EPROM.
Some components on the boards are not used in ETPR and ESTR modules.
In
M-ESTPR module
, additionally, there are two small boards, the SP input and the ECG input
T1
T2
P1
P2
ECG+
Resp
SpO
2
ECG
Lead
Zero
P1
Zero
P2
Start
Wedge
Summary of Contents for S/5 M-NE12STPR
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