Comparative study of pulse pressure variation and central venous pressure in evaluation of fluid status in mechanically ventilated patients after cardiac surgery

Aim.This study aimed to compare pulse pressure variation (PPV) with central venous pressure (CVP) in checking out and optimizing fluid volume in mechanically ventilated patients admitted to intensive care unit after cardiac surgery.
Background.In clinical area, assessment of body fluid and determination of the intravascular volume after major surgeries such as heart surgery is a significant challenge. The initial purpose of intravascular volume assessment in patients with hemodynamic instability is to determine whether they would benefit from fluid administration or not.
Method. In the present study a prospective descriptive-analytic design was used. Thirty mechanically ventilated patients admitted to intensive care units of Rajaee Heart Center, Tehran, Iran, were recruited in the study after cardiac surgery based on inclusion criteria. Data collection tools included demographic and clinical data sheets. Hemodynamic parameters such as CVP, systolic and diastolic pressures (for calculating pulse pressure and its variation) were recorded by bedside monitoring. Cardiac Index (CI) was measured by non invasive continuous cardiac output monitoring (NICCOMO) system. Data were analyzed in SPSS version 20, using statistical tests.
Findings. The mean changes of CVP, before and five minutes after fluid administration, were significantly different (10.10±6.01 mmHg and 12.37±6.34 mmHg, respectively, p=0.015). The mean changes in arterial pulse pressure, before and five minutes after fluid administration, were significantly different (16.94±8.32 mmHg and 12.77±4.02 mmHg, respectively, P=0.005). At the cut point 2.8 lit/min/m2 for CI, the sensitivity and specificity values for PPV>13%, were 0.71 and 0.61, respectively. Also, at the same cut point, the sensitivity and specificity values for CVPConclusion.It seems that in the mechanically ventilated patients after heart surgery, PPV dynamic index is preferred to CVP static index to evaluate and maintain fluid volume.