The Johnson and Johnson Codman ICP Express monitor for measuring inter-cranial pressure is commonly used with the PowerLab data acquisition system to allow users to make recordings from the patients following surgery or trauma to the head. This main parameter measured is often the mean pressure from the ICP Express Unit for prolonged periods (> 24 hours).
The ADInstruments MLAC21 Interface Cable then connects to the back of the Codman ICP box with the DIN plug connecting to the Bridge Amp. Note: The Codman ICP transducer should never be connected directly to the ADInstruments Bridge Amp. The output from the Codman unit simulates a regular transducer, which is why we use a Bridge Amp to provide excitation voltage, zeroing, etc., before recording into the PowerLab.
The Codman has two output gain settings (5uV/Vex/mmHg or 40uV/vex/mmHg – see “Patient Monitor Sensitivity Selection Switch on page 4 of the Codman Instruction Manual ). The factory default is 5uV; however, we suggest that you set the output gain to 40uV/V/mmHg. If the Codman output gain is set at 5uV/V/mmHg, the output amplitude will be very low (i.e. 20mmHg = 0.5mV) and have a low signal resolution in LabChart.
At the 40uV/V/mmHg setting, when used in conjunction with ADInstruments Bridge Amplifier (which provides 6V excitation), every 100mmHg input should give a 24mV output or 0.24mV per mmHg to the PowerLab. The Codman ICP Monitoring System Quick Set-up Guide can be used for more information.
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