Cardiac preload responsiveness in children with cardiovascular dysfunction or dilated cardiomyopathy: a multicenter observational study

Accuracy of dynamic preload variables for predicting fluid responsiveness in patients with pediatric liver cirrhosis: A prospective study

BACKGROUND

We have previously reported that dynamic preload variables predicted fluid responsiveness in adult patients with liver cirrhosis. However, pediatric patients with cirrhosis may present with unique hemodynamic characteristics, and therefore, the predictive accuracy of these variables in such patients must be clarified.

AIMS

To investigate the accuracy of dynamic preload variables for predicting fluid responsiveness in pediatric patients with cirrhosis.

METHODS

A total of 27 pediatric patients with cirrhosis undergoing orthotopic liver transplantation were enrolled in this study. Patients' pulse pressure variation, stroke volume variation, stroke volume index, and central venous pressure were measured using the calibrated pulse contour cardiac output system. The plethysmographic variability index was measured using a Masimo Radical 7 co-oximeter. During the hepatic dissection phase of the surgery, repeated intraoperative fluid challenges with 10 mL kg^-1 of crystalloid within 15 minutes were administered. Fluid responsiveness was defined as an increase in stroke volume index of ≥15% after fluid challenge.

RESULTS

A total of 61 fluid challenges were administered resulting in 15 fluid responders and 46 fluid nonresponders. Fluid challenge induced significant decreases in all three dynamic preload variables but not in the fluid nonresponders. However, the area under the receiver operating characteristic curves for pulse pressure variation, stroke volume variation, plethysmographic variability index, and central venous pressure for predicting fluid responsiveness were 0.67 (95% confidence interval: 0.52-0.82; P = .0255), 0.68 (95% confidence interval: 0.54-0.83; P = .0140), 0.56 (95% confidence interval: 0.40-0.71; P = .4724), and 0.57 (95% confidence interval: 0.40-0.74; P = .4192), respectively.

CONCLUSIONS

Dynamic preload variables do not predict fluid responsiveness in pediatric patients with liver cirrhosis.

Fluid responsiveness in the pediatric population

It is challenging to predict fluid responsiveness, that is, whether the cardiac index or stroke volume index would be increased by fluid administration, in the pediatric population. Previous studies on fluid responsiveness have assessed several variables derived from pressure wave measurements, plethysmography (pulse oximeter plethysmograph amplitude variation), ultrasonography, bioreactance data, and various combined methods. However, only the respiratory variation of aortic blood flow peak velocity has consistently shown a predictive ability in pediatric patients. For the prediction of fluid responsiveness in children, flow- or volume-dependent, noninvasive variables are more promising than pressure-dependent, invasive variables. This article reviews various potential variables for the prediction of fluid responsiveness in the pediatric population. Differences in anatomic and physiologic characteristics between the pediatric and adult populations are covered. In addition, some important considerations are discussed for future studies on fluid responsiveness in the pediatric population.

Transpulmonary thermodilution (PiCCO) measurements in children without cardiopulmonary dysfunction: large interindividual variation and conflicting reference values

BACKGROUND

The PiCCO system, based on transpulmonary thermodilution, is one of the few tools available for continuous hemodynamic monitoring in children. However, published data for some of the derived variables reveal indexed values that seem questionable.

AIMS

The aim of this study was to collect data from hemodynamically normal children and compare these to existing reference values. Furthermore, we sought to explore if indexing some of the variables differently could improve the clinical application of the obtained values.

METHODS

This is a prospective observational study in a tertiary university hospital including 31 children without cardiopulmonary disease scheduled for major neurosurgery. Measurements were performed after induction of general anesthesia.

RESULTS

Median age was 8 months. PiCCO-derived median Cardiac Index (CI) was 3.8 l · min(-1) · m(-2) (range 2.6-6.6), reference range 3.0-5.0, median Global End-Diastolic Volume Index (GEDVI) was 366 ml · m(-2) (range 269-685), reference range 680-800, whereas median Extravascular Lung Water Index (EVLWI) was 12 ml · kg(-1) (range 7-31), reference range 3-7. All measured variables had a high interindividual variation, especially in children weighing less than 15 kg.

CONCLUSIONS

Values obtained by the PiCCO system in children have a wide range, and should therefore be interpreted with caution. Current reference values published for GEDVI and EVLWI are not applicable in children; the former is too high and the latter too low, and should not guide clinical practice. Indexing by other physiological indices may reduce this problem. Using current variables, we find GEDVI 280-590 ml · m(-2) and ELWI 7-27 ml · kg(-1) to be typical ranges for children.

Predicting fluid responsiveness in 100 critically ill children: the effect of baseline contractility

PURPOSE

Fluid overload is a risk factor for poor outcome in intensive care; thus volume loading should be tailored towards patients who are likely to increase stroke volume. We aimed to evaluate the paediatric predictive ability (stroke volume increase of at least 15 % after fluid bolus) of novel and established volumetric and dynamic haemodynamic variables, and assess the influence of baseline contractility on response.

METHODS

We assessed 142 volume loading episodes (10 ml/kg crystalloid) in 100 critically ill ventilated children, median (interquartile) weight 10 (5.6-15) kg. Eight advanced haemodynamic variables were assessed using two commercially available devices. Systemic ventricular contractility was measured as the maximum rate of systolic arterial pressure rise.

RESULTS

Overall, predictive ability was poor, with volumetric variables performing better than dynamic (area under receiver operating characteristic curves ranged from 0.53 to 0.67). The best predictor was total end-diastolic volume index; however, this did not increase in a consistent way with volume loading, with change post volume being weakly related to baseline values (r = -0.19, p = 0.02). A multivariable model quantified the importance of contractility in stroke volume response. Children with high baseline contractility (≥75th centile) typically achieved a positive stroke volume response when end-diastolic volume values changed by 10-15 ml/m(2.6), whereas patients with low contractility (≤25th centile) typically required end-diastolic volume increases of 35-40 ml/m(2.6).

CONCLUSIONS

Current paediatric predictors of volume response perform poorly; prediction may be improved if baseline contractility is taken into account.