The Pressure Recording Analytical Method, invasive hemodynamic monitoring, is an uncalibrated pulse contour analysis, installed in the Mostcare® system that allows a continuous estimation of the stroke volume and thus the cardiac output, by the relationship between the area under the curve of the systolic portion of the arterial blood pressure curve and the dynamic impedance of the cardiovascular system.

The objectives of the study are to determine if the parameters measured by Mostcare® make it possible to predict the response to volume expansion in pediatric surgical critical care patients, sedated, intubated and ventilated, by comparing the changes in stroke volume, induced by a volume expansion, measured by trans-thoracic echocardiography.

Children undergoing major surgery or severe trauma with bleeding require regular hemodynamic evaluation, including cardiac output measurement, to maintain adequate organ perfusion. In fact, administration of fluid to improve cardiac output is the mainstay of hemodynamic resuscitation. However, not all patients respond to fluid therapy, and excessive fluid administration is harmful. Therefore, the vascular filling strategy requires a thorough hemodynamic evaluation.

Many predictive tools for fluid responsiveness have been validated in adults, and are based on heart-lung interaction in ventilated patients. Up to now, respiratory variation in aortic blood flow peak velocity, measured by transthoracic or transoesophageal cardiac echocardiography, is the only variable shown to effectively predict fluid responsiveness in children.

However, the use of these methods does not allow continuous monitoring (trans-thoracic echocardiography) or is not easily achievable in current practice (trans-esophageal echocardiography). In addition, these monitoring tools require learning and inter- and intra-individual variability is not negligible, ranging from 1% to 20%.

The Pressure Recording Analytical Method, invasive hemodynamic monitoring, is an uncalibrated pulse contour analysis, installed in the Mostcare® system, that allows a continuous estimation of the stroke volume and thus of the cardiac output, by the relationship between the area under the curve of the systolic portion of the arterial blood pressure curve and the dynamic impedance of the cardiovascular system.

The goal of this study is to assess the ability of dynamic cardiovascular variables measured using Mostcare® to predict fluid responsiveness in pediatric surgical critical care patients, sedated, intubated and ventilated, in prone position, by comparing the changes in stroke volume (SV), induced by a volume expansion (VE), measured by trans-thoracic echocardiography. For the purpose of the study, responders (Rs) to VE are patients showing an increase in SV measured using transthoracic echocardiography of at least 15% after VE.

Inclusion Criteria:

• Children aged 0 to 10 years old, of both sexes.
• Perioperative period of surgery under general anesthesia requiring admission to surgical resuscitation (before and / or after the surgical procedure).
• Patients admitted for severe trauma.
• Patient installation: supine position.
• Intubation and mechanical ventilation: tidal volume: 7 to 8 ml / kg, Positive expiratory pressure : 3-4 cm H2O, inspiration / expiration: 1 / 1.5 to 1/2; respiratory rate: 1 month up to 2 years = 30 / min; children 2-8 years = 20 / min; children> 8 years = 15 / min.
• Patients with arterial catheters.
• Need for a volume expansion : indication given by the doctor in charge of the patient.
• Non-opposition expressed by the holders of parental authority.

Exclusion Criteria:

• Cardiac rhythm disorders (in particular atrial fibrillation, junctional tachycardia, ventricular arrhythmias), with the exception of sinus tachycardia, respiratory variations of heart rate and sporadic atrial / ventricular extrasystoles whom will allow inclusion.
• Cardiopathy: severe systolic dysfunction (shortening fraction <28%, ejection fraction <50%); valvulopathy (significant narrowing or valvular insufficiency); left-right shunt, persistent arterial duct.
• Unstable hemodynamic status related to active bleeding requiring vascular filling > 2 mL / kg / min or requiring vasopressor or inotropic therapy whose dosage had to be changed in the last five minutes.
• Need for mechanical ventilation with a tidal volume> 10 mL / kg or <7 mL / kg.
• Refusal of the patient or the holders of parental authority to exploit the collected data.
• Impossibility to carry out measurements.

Patients between birth and 10 years of age admitted to the pediatric surgical ICU of the Necker-Enfants Malades university hospital and for whom volume expansion is indicated.