12 Monitoring Cardiac Output
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Pulse Pressure Variation (PPV) is calculated from beat-to-beat arterial pressure values. Pulse pressure
is the difference between the systolic and the diastolic pressure values for a single beat. Pulse pressure
variation is defined as the maximal pressure less the minimum pressure divided by the average of these
two pressures.
WARNING
• The monitor calculates PPV from beat-to-beat values of the arterial pressure selected for CCO.
The circumstances under which the calculation of a PPV value is clinically meaningful, appropriate
and reliable must be determined by a physician.
• The clinical value of the derived PPV information must be determined by a physician. According
to recent scientific literature, the clinical relevance of PPV information is restricted to sedated
patients receiving controlled mechanical ventilation and mainly free from cardiac arrhythmia.
• PPV calculation may lead to inaccurate values in the following situations:
– at respiration rates below 8 rpm
– 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
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