Prandial effects on portal venous anastomosis Doppler-ultrasound measurements in pediatric liver transplant recipients.

Children with a livertransplant undergo frequent Doppler-ultrasound to assess
patency of the livervasculature and possible complications such as stenoses. In
addition biliairy duct complications, liverparenchyma abnormality, and
formation of collaterals due to portal hypertension are examined. These
children have to fast prior to this ultraound, which results in them being
hungry and in turn causes distress for the child and the parents. The reason to
keep these children fasted is because the reference values from
Doppler-ultrasound used to determine abnormal findings are based on fasted
patients.
However when a child has its breakfast/lunch the mesenterial flow will
increase, in which case it is unknown how this affects the measurements and
whether the reference values can still be applied. There are two methods of
diagnosing a portal vein anastomosis stenosis, the first is measuring the
intra-anastomotic flow velocity and applying a threshold of equal or more than
125cm/s, the second is a ratio between pre- and intra-anastomotic flow velocity
of 1:3 or higher. The hypothesis is that when using the first method the
increased flow will disturb the measurements in such a way that a
non-significant stenosis could be regarded as a significant stenosis
postprandially. We expect that the second method would not be affected by
increased mesenteric blood flow. The need for research with children instead of
adults results from the difference in diameter of the native portal vein
compared to the donor portal vein (usually adult size), as a result findings in
adults cannot be readily extrapolated to children.

To investigate if currently employed ultrasound measurements for diagnosing a
portal vein anastomosis stenosis remain reliable when children are not fasting

Prospective observational.

No risk. Minimal burden from having to undergo a short (10min) extra abdominal
ultrasound after breakfast/lunch.