Clinical oedema is seen after open heart surgery with the use of cardiopulmonary bypass and hypothermia in children. The oedema formation is due to increased fluid transport from blood to tissue. This transcapillary fluid transport is dependent on differences in interstitial and plasma colloid osmotic pressure. The purpose of this investigation is to evaluate changes in interstitial colloid osmotic pressure before, under and after the use of cardiopulmonary bypass in children. The study hypothesis is that oedema developed during cardiopulmonary bypass and hypothermia is caused by increased micro vascular protein leakage and reduced colloid osmotic pressure gradient through the capillary membrane.

Inclusion Criteria:

• The diagnosis of a congenital heart defect
• scheduled for open heart surgery with the use of cardiopulmonary bypass
• under 13 year of age
• informed consent obtained from the parents

Exclusion Criteria:

• renal failure
• liver failure

Children scheduled for open heart surgery with the use of Cardiopulmonary Bypass at Oslo University Hospital