Background: Prediction of parameters of fluid responsiveness can identify patients who will benefit from fluid loading in the immediate post-operative period of cardiac surgery. Several hemodynamic parameters may help identify those who will benefit from hydration. This study aimed to identify and compare the parameters that predict fluid responsiveness in post-cardiac surgery patients.
Method: This prospective cohort study included 101 post-cardiac surgery patients. Hemodynamic parameters were recorded at baseline and after an 8 ml/kg IV fluid challenge. Fluid responders are those with an increase in stroke volume of ≥15%. Multivariate analysis was used to identify independent predictors of fluid responder status. Sensitivity and specificity analyses were done to determine the predictive accuracy of each parameter.
Results: The rate of fluid responsiveness in this study was 54.5%. Independent predictors were: Central venous pressure (CVP) ≤6 mmHg (p=0.001), pulmonary artery occlusion pressure (PAOP) ≤12 mmHg (p=0.016), PAOP increase by ≥7 mmHg (p=0.002), pulse pressure variability (PPV) >12% (p<0.005), PPV decrease by >5% (p=0.049) and weight (p=0.04). PPV was the most sensitive (92%) and specific (74%); while PAOP was the least sensitive (70%) and CVP the least specific (51%). PPV had the highest ability to discriminate fluid responders (AUC 0.83) compared to PAOP (AUC 0.21) and CVP (AUC 0.40) (p<0.0005).
Conclusion: PPV (a dynamic index) is superior to CVP and PAOP (static indices) in discriminating fluid responders in adult patients who underwent cardiac surgery. PPV is the favored tool to guide initiation of fluid therapy in this clinical set