A pilot study of the epidemiology and associations of pulse pressure variation among non-cardiac surgery critically ill patients

Background: A pulse pressure variation (PPV) ≥13% of mean arterial pressure (MAP) is an accepted marker of a fluidresponsive state. However, there is no study of its epidemiology and associations among non-cardiac critically ill patients. Objectives: To conduct a pilot study of the epidemiology and associations of a PPV ≥13% among non-cardiac critically ill patients. Design: Prospective observational study. Setting: Intensive care unit of a university hospital. Patients: Cohort of 37 sedated critically ill patients undergoing mandatory ventilation. Main outcome measures: PPV values, tidal volume and peak airway pressure, MAP, heart rate (HR) and central venous pressure (CVP) collected every 15 minutes; fluid balance collected hourly; correlation between PPV and these variables. Results: 450 PPV measurements were collated. The PPV value was ≥13% in 86 (19%) measurements and was observed in two consecutive measurements in 68 (15%) of cases. On multivariable analysis, mean PPV was significantly correlated with CVP (P=0.04), HR (P<0.001) and peak airway pressure (P=0.001), but not fluid balance (P=0.3). Conclusions: Among non-cardiac surgery mechanically ventilated patients, a PPV in the fluid-responsive range was present in one-fifth of measurements and showed logical correlations with relevant haemodynamic and mechanical ventilation-related variables. Our results provide a rationale for a more comprehensive evaluation of PPV measurement in suitable critically ill patients.