Assessment of cardiac preload status by pulse pressure variation in patients after anesthesia induction: comparison with central venous pressure and initial distribution volume of glucose

Abstract

Recognition of intraoperative hypovolemia is important for fluid management. Previous studies demonstrated functional preload parameter pulse pressure variation (PPV) could predict volume changes in response to fluid loading and loss. In this study, we examined the correlation between PPV and other two cardiac preload indicators, central venous pressure (CVP) or initial distribution volume of glucose (IDVG), in patients after anesthesia induction. In 30 patients undergoing scheduled craniotomy surgery, we compared measurement of PPV (%) using the Ohmeda monitor method to simultaneously measure CVP and IDVG after anesthesia induction through correlation analysis and receiver operating characteristic (ROC) curves. Pulse pressure variation has negative linear correlation with IDVG (r = -0.65, P < 0.01). IDVG values (n = 13) when PPV ≥ 11% showed a significant difference compared with those (n = 17) when PPV < 11% (P < 0.001). The ROC curve showed the best cutoff value of IDVG is 122 ml/kg, equivalent to the threshold of PPV (11%) for predicting fluid responsiveness. However, there is no significant correlation between CVP in normal ranges (4-9 mmHg) and PPV (r = -0.12, P > 0.05). As an indicator of cardiac preload, PPV has a negative linear correlation with IDVG in patients after anesthesia induction. It does not correlate well with CVP in the normal range. Our results imply that an individual PPV, not CVP, is equivalent to IDVG in assessing volume status after induction.