15 Monitoring Airway Flow, Volume and Pressure
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circuit). Lavage and suctioning of the airway can then be performed without fluids and mucous
accumulating on the airway adapter windows.
• Measurement values provided by a ventilator may differ significantly from the values provided by
the spirometry module, due to different locations of the flow sensor.
• Incorrect entry of gas compensation parameters (i.e. temperature, gas composition) may reduce
the accuracy of the measured values.
• An abnormal volume waveform as displayed below may be an indicator of an air leak:
In general, if
MVexp or TVexp are significantly smaller than MVin or TVin, the tubing should be
checked for leaks.
Zero Calibration
The zero calibration maintains the accuracy of the spirometry waves and numerics by regularly
compensating for drifts within the measurement section. It is performed automatically without user
interaction and takes about 2 seconds to complete. The automatic zero calibration is normally carried
out every ten minutes. During warm-up or when the ambient pressure changes, this interval may be
reduced to two minutes.
During the zero calibration the waveform is flat but the numerics remain on the screen. Typically, a
zero calibration is started at the beginning of a respiration cycle, therefore a waveform may begin
normally and then immediately become flat for the time of the zero calibration.
Automatic Purging
A double lumen connecting line (tubing) connects the flow sensors to the patient monitor. The
M1014A Spirometry Module includes an automatic and manual purge feature which provides a flush
of room air to keep the sensor tubing free from water condensation and patient secretions. This
feature is available for the adult, pediatric, and neonatal modes. The purge will begin with the
exhalation portion of the ventilator cycle.
NOTE
• During the purge cycle the pump will be heard
1 Zero Calibration
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