The purpose of this study is

• To assess the value of dynamics (SVV, PPV) and static indices (GEDVI, ITBVI, CVP) of preload and its combination with contractility (CI,SV, ventricular power, dP/dtmax, CFI, GEF) and lung water indices (ELWI), as predictors of fluid responsiveness in both spontaneously breathing and mechanically ventilated pediatric patients.
• To assess the value of stroke volume and pulse pressure changes from femoral pulse contour analysis (PiCCO2) during passive leg raising as predictor of fluid responsiveness in pediatric patients.
• To establish normal and cutoff values of transpulmonary thermodilution (PiCCO2) hemodynamic variables in hemodynamically stables and hemodynamically "normal" patients.

One of the ongoing challenges in critical care has been determining adequate fluid resuscitation. Overly aggressive volume expansion may produce deleterious effects, especially in patients with respiratory, renal and/or cardiac failure. Since the clinical ability to judge hemodynamic parameters is known to be poor, the determination of variables that would predict response to fluid challenge would be important for clinical decision-making.

Traditional measures of preload (CVP, PAOP) are now known to be incapable to assess the volume status and fluid responsiveness, especially in children.

There are two kinds of reasons for explaining the failure of markers of preload to predict volume responsiveness: the first reason is that the markers commonly used at the bedside are not always accurate measures of cardiac preload; the second reason is that an assessment of preload is not an assessment of preload responsiveness.

The rapid determination of hemodynamic status offered by noninvasive hemodynamic devices as PICCO2 would allow tailoring of volume expansion necessary in hypoperfusion states to increase left ventricular volume and cardiac output. Studies in critically ill adults patients have demonstrated that passive leg raising autotransfusion and functional hemodynamic monitoring, by using pulse contour analysis, are reliable in the detection of fluid responsiveness. However, currently we have very few studies in pediatric patients using arterial pulse contour analysis and transpulmonary thermodilution, which does not allow the rational application of the hemodynamic variables for guiding fluid resuscitation.

This study pretend to assess 1) the value of dynamics and static indices of preload, and its combination with contractility and lung water indices, as predictors of fluid responsiveness in both spontaneously breathing and mechanically ventilated pediatric patients and 2) the value of stroke volume and pulse pressure changes during passive leg raising autotransfusion, as predictors of fluid responsiveness in pediatric patients.

In this observational study, the hemodynamical variables are registered during the hemodynamically unstable, stable and "normal" states of the pediatric patient and before and after clinically indicated fluid (crystalloid, colloid or hemoderivative) infusion. Passive leg raising hemodynamic changes will be compared with the hemodynamic changes caused by fluid infusion.

Inclusion Criteria:

• Pediatric patients admitted to PICU
• Patient equipped with a femoral arterial catheter and central venous catheter or who requires advanced hemodynamic monitoring
• Parents consent

Exclusion Criteria:

• Absolute

  • Patient with left to right cardiac shunts
  • Patient with extra-corporeal life support
  • Less than 4 Kg body weight

• For passive leg raising procedure

  • Patient with head trauma or intracranial hypertension
  • Patient in prone position
  • Patient who may not tolerate supine or Trendelenburg position: ej. Glenn procedure
  • Patient with hip injury

Pediatric patients admitted to the PICU equipped with a femoral arterial catheter and a central venous catheter or who require advanced hemodinamic monitoring