Cerebral Circulation in Critically Ill Children

"Regional Cerebral Oxygen saturation (rScO2 ) values will be collected for all patients during the procedure using a 2-wavelength (730-810 nm) cerebral oxymeter (monitor INVOS 5100C®, Medtronics). Two transducers will be placed on both fronto-parietal sides of the patient's head.~To assess the balance between oxygen delivery and consumption, the Fractional cerebral Tissue Oxygen Extraction (FTOE) will be calculated as this ratio: FTOE=\[SpO2-rScO2\]/SpO2.~Data will be collected for a period of 3 hours starting from the beginning of catecholamine treatment."

"Transcranial Doppler ultrasound will be performed for all patients during the procedure using a VIVID S-5 (General Electric®) echograph. All examinations will be performed by a single trained operator. A 3 MHz probe will be placed on left and right temporal window to detect signal from the middle cerebral artery. 2 measures will be performed for each side to have the mean of the two measures; In case of difference in measures of more than 20%, a third measure will be performed.~Measures will be performed for a period of 3 hours starting from the beginning of catecholamine treatment."

"Transthoracic echocardiography will be realized for all patients during the procedure using a transthoracic ultrasound device (VIVID S-5, General Electric®) with a 3 to 6 MHz probe. All examinations will be performed by a single trained operator.~Two echocardiographic views will be examined to assess cardiac output : the two-chamber long-axis view to measure sub-aortic diameter (d), and the four-chamber view to measure the Left ventricular outflow tract velocity time integral (LVOT VTI). Cardiac output (Qc) will then be calculated taking account these parameters and heart rate with this formula : Qc = \[π x d2 x VTI x HR\] / 4 2 measures will be performed to have the mean of the two measures; In case of difference in measures of more than 20%, a third measure will be performed.~Measures will be performed for a period of 3 hours starting from the beginning of catecholamine treatment."