To predict fluid responsiveness in anesthetized pediatric patient is not an easy task although anesthesia provider has to deal with this question on their daily practices. Today, very few parameters can help anesthesia provider to predict fluid responsiveness in the pediatric anesthetized patient. Therefore anesthesia provider are let with fluid challenge with high volume of fluid boluses to see if patient were fluid responsive or not. This could lead to fluid overload and it's associated morbidity. We would like to investigate if the cardiac output response to a mini fluid challenge of 3 ml/kg in 2 minutes would be predictive of the response to an usual fluid challenge of 15 ml/kg in 10 minutes in elective pediatric anesthetized patients.

The main objective is to determine whether the new test "the stroke volume variation after fluid challenge of 3ml/Kg" provides information about fluid responsiveness namely increased cardiac output. This new test will be compared to "gold standard" that is, "the stroke volume variation after standard fluid challenge of 15ml/Kg". It is the evaluation of the diagnostic accuracy of a diagnostic test based on an index obtained by transthoracic cardiac echocardiography for diagnosing fluid responsiveness. This index is the stroke volume variation measured by transthoracic cardiac echography.

The study will include anesthetized patients undergoing scheduled surgery. For hemodynamic optimization, these patients will benefit, early after anaesthetic induction, before the surgical procedure has started, from a fluid challenge of 15ml/kg achieved in two stages (3 ml/Kg then 12 ml/kg) separated by an interval of one minute. Three-time hemodynamic will be analyzed.

• T0: basal
• T1: one minute after first vascular filling with 3ml/Kg in 2 minutes
• T2: one minute after second vascular filling with 12 ml/Kg in 8 minutes which is performed one minute after the end of the first filling (a total of 15 ml/kg)

At each time, we will retrieve a collection of hemodynamic data (stroke volume, cardiac output) obtained by transthoracic echocardiography, standard method to assess fluid responsiveness. And at the same times, the PVI and hemodynamic parameters obtained by esophageal Doppler will be noted.

Inclusion Criteria:

• pediatric patient for scheduled surgery
• from 8 to 30 kg of weight

Exclusion Criteria:

• denied from the child or their parents
• congenital cardiopathy
• cardiovascular shunt
• respiratory dysfunction
• hepatic dysfunction
• renal dysfunction
• intracranial hypertension