Pulse pressure variation with respiration (PPV) predicts fluid responsiveness in mechanically ventilated patients. Because this is due to transmission of airway pressures to the vasculature, it is hypothesised that low tidal volume ventilation (or non compliant lungs, or both) results in less PPV even in fluid-responsive patients. This was confirmed in a study looking at the effect of airway driving pressure (Pplat – PEEP) on PPV. The study confirmed the positive predictive value of a high PPV, but some of those patients with a ‘low’ PPV (below a commonly accepted cut-off of 13%) were still fluid responsive, which was defined as a 15% or more increase in stroke index after a fluid challenge. In fluid responders with a low PPV, (Pplat – PEEP) was less than or equal to 20 cmH20.
Take home message: In mechanically ventilated patients, PPV values <13% do not rule out fluid responsiveness, especially when (Pplat – PEEP) was less than or equal to 20
The influence of the airway driving pressure on pulsed pressure variation as a predictor of fluid responsiveness
Intensive Care Med. 2010 Mar;36(3):496-503