UMEM Educational Pearls

Hemodynamic Monitoring in the Ventilated Patient

  • Consider pulse pressure variation (PPV) as a method to monitor volume responsiveness in your mechanically ventilated ED patients.
  • The theory behind PPV:
    • When a positive pressure breath is delivered via the ventilator, pleural pressure rises and causes a decrease in venous return, right heart filling, and right heart output.
    • Simultaneously, the positive pressure breath causes an increase in left heart filling and a decrease in left heart afterload.  This is reflected clinically as an increase in blood pressure.
    • Within a few beats, the decreased right heart output is transmitted to the left heart resulting in a decrease in blood pressure during expiration.
  • Patients who are volume depleted can have significant differences in blood pressure between inspiration and expiration - i.e. a large variation in pulse pressure.
  • PPV values > 12% have been shown to identify patients who are volume responsive.
  • Importantly, PPV works best in vented patients who have no spontaneous respiratory effort, are in sinus rhythm, and receiving 8 ml/kg tidal volumes.


Magder S. Hemodynamic monitoring in the mechanically ventilated patient. Curr Opin Crit Care 2011;17:36-42.