11 Monitoring Invasive Pressure
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– during ventilation with tidal volumes lower than 8 ml/kg
– for patients with acute right ventricular dysfunction ("cor pulmonale").
• The PPV measurement has been validated only for adult patients
To select an arterial pressure as PPV source:
1 In the Main Setup menu, select Measurements.
2 In the Setup PPV menu, select ABP, ART, Ao, BAP, P or FAP as the arterial pressure source.
CAUTION
Older Multi-Measurement modules cannot supply a beat-to-beat arterial pressure value. In this case the
monitor shows a
NO PPV FROM<Server> INOP.
Measuring Pulmonary Artery Wedge Pressure
Pulmonary Artery Wedge Pressure (PAWP) values, used to assess cardiac function, are affected by:
• Fluid status
• Myocardial contractility
• Valve and pulmonary circulation integrity
Obtain the measurement by introducing a balloon-tipped pulmonary artery flotation catheter into the
pulmonary artery. When the catheter is in one of the smaller pulmonary arteries, the inflated balloon
occludes the artery allowing the monitor to record changes in the intrathoracic pressures that occur
throughout the respiration cycle. The pulmonary wedge pressure is the left ventricular end diastolic
pressure (preload).
The most accurate PAWP values are obtained at the end of the respiration cycle when the intrathoracic
pressure is fairly constant. You can use the respiration waveform as a reference when assessing the
PAWP waveform, to ensure constant measurement timing relative to the respiratory cycle. The
monitor displays the PAWP value for up to 24 hours or until you admit a new patient.
WARNING
The pressure receptor in the catheter records pressure changes that occur only in front of the
occlusion. Even though the catheter tip is in the pulmonary artery, the receptor records pressure
changes transmitted back through the pulmonary circulation from the left side of the heart.
While performing the wedge procedure, the monitor switches off the pressure alarms for pulmonary
artery pressure (PAP).
Due to a slight measurement delay, you should not use sidestream CO
2
as a direct reference for
determining the end expiratory point in the pressure curve.
To start the Wedge procedure,
1 In the Main Setup menu, select Wedge to display the wedge procedure window.
2 Prepare and check the pressure line according to your hospital policy.
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