Predicting Fluid Responsiveness in Children Undergoing Cardiac Surgery After Cardiopulmonary Bypass

Dynamic parameters of fluid responsiveness (FR), namely aortic blood flow velocity variation (delta V peak), left ventricular velocity-time integral variation (delta VTI), stroke volume variation, and pulse pressure variation (PPV) have demonstrated good diagnostic performance for the prediction of response to fluid loading in mechanically ventilated critically ill adult patients. We aimed to evaluate these parameters in children undergoing cardiac surgery. A retrospective observational study of mechanically ventilated patients weighing less than 20 kg who received a volume expansion (VE) of 10 ml/kg after sternal closure was conducted. A 10% cardiac index (CI) increase divided patients into 7 responders (R) and 9 non-responders (NR). Transesophageal echocardiography and Pressure Recording Analytical Method data were retrieved. The percentage CI increase was 18.6 (12)% in R and 2.9 (5.7)% in NR (p = 0.037). Prior to VE, delta V peak, delta VTI, PPV, and SPV differed between R and NR (p = 0.045, 0.043, 0.048, 0,037 and 0.044, respectively). Systolic (p = 0.004), diastolic (p = 0.002), mean blood pressure (p = 0.003), delta V peak (p = 0.03), delta VTI (p = 0.04), CI (p = 0.01), PPV (p = 0.04), SPV (p = 0.04), and dP/dt max (maximal pressure-to-time ratio) (p = 0.02) changed the following VE in R patients. Delta V peak decreased after VE in NR patients (p = 0.004). Delta VTI and PPV showed the highest predictive values, with area under receiver operator characteristic curves of 0.76 (p = 0.049) and 0.76 (p = 0.045), respectively. Delta VTI and PPV were revealed to be potential predictors of FR in ventilated children after cardiac surgery. Their combined evaluation could be useful for fluid management after sternal closure.