Strategies for optimisation of paediatric cardiopulmonary bypass

The aim of this thesis is to address different aspects of paediatric cardiopulmonary bypass in detail and to propose modifications in order to reduce cardiopulmonary bypass related morbidity and by doing so, improve patient outcome. We will focus on four major items: (1) vascular access, (2) mass transfer and fluid dynamics of oxygenators, (3) circuits and (4) whole body inflammatory reaction. • The small vascular structures of the new-born demand a better design description of the geometry and fluid dynamic characteristics of cannulas. There is not only a need for a better validation of today’s cannulas but also for research into the relation between the hemodynamic characteristics of these cannulas and possible damage to blood elements. • The oxygenator is prone to less optimal flow, due to its tortuous flow path, its large foreign surface area and the rapid changes in blood velocity resulting in non-optimal mass transfer and activation of the whole body inflammatory response. Additionally, most oxygenators have a priming volume that is too high compared to the total blood volume of a new-born. There is an urgent need for smaller, more blood compatible oxygenators, with optimisation of their fluid mechanics and gas exchange in order to fit the paediatric needs. These needs will include the capability for achieving subnormal arterial oxygen tensions in cyanotic children without compromising the high oxygen consumption of children during rewarming. • Most circuits today have been designed based on empirically derived data. This results in large volumes in the arterial and venous lines as well as in the aspiration lines. The use of an arterial line filter is highly recommended although it is not used in an appropriate way in most institutions. • Finally, the use and conduct of a paediatric cardiopulmonary bypass will end in a mild or more pronounced whole body inflammatory reaction. The strength of this reaction will vary from child to child, the equipment used, and the conduct of the bypass. We will propose techniques and strategies to overcome or to reduce these problems and by doing so to ameliorate the cardiopulmonary bypass related morbidity.