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Zeroing a transducer

Monitoring zero 3

Figure 3a. Three way tap connecting vessel in patient to transducer. The system is not zeroed yet and the measurement of the pressure is not accurate.

Monitoring zero 2

Figure 3b. To zero the line, the 3-way tap at the transducer is opened so that the transducer is exposed to atmospheric pressure. The ‘zero pressure’ button is pressed on the monitor (thus the monitor has a reference for pressure that equates to zero).

Monitoring zero 3

Figure 3c. The 3-way tap is then turned to read the patients pressure. This time the measurement is accurate because it is done after the system has been zeroed.

The transducer should be positioned at the level of the pressure to be measured during zeroing and during measurement. In case of arterial or central pressure, the transducer should be positioned at the level of the heart. If the transducer is too low then the pressure reading will be inaccurately high and visa-versa. Beware if the level of the bed alters without the transducer, as this will provide inaccurate readings.

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