Work package 4
Devices and techniques for vascular access
Lead: Deutsches Herzzentrum München, Dr. med. Stanimir Georgiev
Development of cannulas and insertion techniques for large-bore vascular access incl. first in-vitro and in-vivo testing of umbilical excess and alternative access routes
4.1 Definition of hemodynamic needs
Defining an algorithm for calculating the interdependencies of flow resistance in the artificial placenta components (lines, devices, connectors), diameters and lengths of cannulas with respect to blood pressure and flow needed to predictably rise oxygenation for different groups of body weight. Similar fluid dynamical approach as used for WP 3 will be applied.
4.2 Development of best practice strategy for cannulation
The clinical partners and the engineering partners will develop a best practice strategy for the reliable cannulation of the umbilical vessels under ultrasound guidance in close cooperation. This includes the use of a placeholder catheter which will be inserted into the umbilical vessel to keep the umbilical vessel open by insertion right after birth to enable the decision-making process. For the insertion, techniques known from other applications in pediatric interventional cardiology, such as the use of guidewires for reaching difficult anatomical positions and using them to exchange catheters, will be considered. All phases of the intervention including insertion, dilatation of the vessel to enable enough flow, fixation of the catheter and retraction will be considered. The requirements and challenges will be defined to serve as an input for subsequent WPs.
4.3 Evaluation of concepts using functional prototypes
Based on the results of work package 4.2, concepts to solve the different tasks will be developed. Extrusion and bonding technologies will be used for the catheter parts, and balloons will be produced by blow moulding using medical-grade thermoplastic materials. Functional prototypes are built to evaluate the concepts. These include but are not limited to the following: 1) Pre-shaped or steerable catheter for first cannulation, 2) Insertion of a dilator following a thin stretchable catheter, 3) Integration of a mechanism into the catheter wall that allows change of catheter diameter, 4) Bioabsorbable catheter material for easier retraction, 5) Fixation device for the catheter. For evaluation of the concepts, a model will be set up.
4.4 Development of cannulation system including refinement/testing and training
The functional prototypes developed in work package 4.3 will be integrated into an overall concept of the cannulation system. Prototype production of the cannulation system including all components (placeholder catheter, guidewire, balloon catheter, dilators). The prototypes will be tested by the clinical partners in-vitro and in-vivo using DHM's piglet model (n = 7 successful) and accordingly refined. The development of devices and the development of the cannulation technique are interdependent processes of close mutual collaboration. The cannulas will finally be tested in WP 3.4.
4.5 Vascular access routes
Alternative access routes must be evaluated for situations where the umbilical vessels are not accessible. Access sites include jugular, carotidal, femoral and transhepatic puncture sites as well as alternative concepts of catheterisation of the pulmonary artery, persistent ductus arteriosus, right or left atrium under ultrasound guidance. While the ultrasound guided catheterisation in preterm infants is already a recently developed technique, yet these concepts will require modified cannulas. It will be tested in piglet models (n = 7 successful).
4.6 Intermittent vascular access device optimisations
based on short- and long-term in-vivo experiences
All Workpackages
Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union. Neither the European Union nor the granting authority can be held responsible for them.