Arterial Line - Pulse Pressure Variation (PPV)

Pressure Variation (PPV) represents an interaction between lungs and heart. Ventilation (either spontaneous or mechanical) alters the intrathoracic pressure and causes stroke volume to vary. Greater variability in stoke volume (increased PPV) may suggest fluid responsiveness.

   PPV = (PPmax - PPmin) / PPmean

Specifically, a PPV > 12% is suggestive that there will be an increase in stroke volume with fluid challenge. However in order to interpret PPV 3 conditions must be met:

  1. Sinus rhythm (consistent filling time)

  2. Mechanically ventilated w/o spontaneous respirations;

  TV= 8 cc/kg (consistent effect of ventilator)

3. Must not have an open chest (heart/lungs interacting)

In contrast to an increase in BP with respiration causing high PPV, pulsus pardoxus is the decrease in SBP > 10 mmHg with respiration, associated with tamponade & other conditions.



- Nick Mark MD @nickmmark



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