Evaluation of the Occurrence of Early Thrombosis on Central Venous Catheter by Ultrasound in Pediatric Intensive Care Unit

"First ultrasound scan from 1 day to 6 days after the placement of the percutaneous central venous catheter.~Second ultrasound scan from 7 days to 13 days after the placement of the percutaneous central venous catheter if no thrombosis was detected at the first ultrasound scan."