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10 Specifications and Theory of Operation
M1132382
10-15
O2 monitoring theory
of operation
O2 monitoring measures O2 concentration in the patient circuit. The
O2 concentration measured from the O2 cell is shown on the
ventilator display.
The O2 sensor is an electrochemical device (galvanic cell). Oxygen
diffuses through a membrane into the cell and oxidizes a base metal
electrode. This oxidation produces an electrical current proportional
to the partial pressure of the oxygen at the electrode’s sensing
surface. The base metal electrode gradually wears out from the
oxidation process.
The voltage from the cell cartridge is affected by the temperature of
the monitored gas mixture. A thermistor in the cell’s housing
automatically compensates for temperature changes in the cell.
O2 monitoring uses signal processing and analyzing circuitry to
convert the cell signal into a corresponding % oxygen value. The
system displays this value and compares it to saved alarm limits. If
the value falls outside the limits, the monitor produces the appropriate
alarms.
Modes
The system has the following modes of mechanical ventilation:
•
Volume Control Ventilation (VCV).
• Pressure Control Ventilation (PCV) (optional).
• Synchronized Intermittent Mandatory Ventilation with Pressure
Support Ventilation (SIMV/PSV) (optional).
• Pressure Support Ventilation (PSVPro) (optional).
• Synchronized Intermittent Mandatory Ventilation with Pressure
Control (SIMV-PC) (optional).
• Pressure Control Ventilation-Volume Guaranteed (PCV-VG)
(optional).