Answer: C
Access insufficiency is the main limitation for cannulation using the Seldinger technique. Although the size of the target vessel e.g. IVC is larger, because cannula size is selected to be smaller than the access vessel diameter (e.g. the common femoral vein), the latter becomes the main limiting factor to flow limitation. The smart canula® is a newer generation of cannulas which collapses over a mandrel to 18F prior to insertion, but re-expands in-situ to 36F or 45F when the mandrel is removed, and its size is limited only by the size of the target vessel. In addition, due to its thinner walls and uncovered design, flow is increased as compared to a standard percutaneous cannula. Removal of the smart canula® requires simple traction which collapses the cannula for withdrawal.
Another newer generation of cannula is the Avalon Elite bicaval dual lumen catheter® designed for single site insertion via the right internal jugular vein for extracorporeal life support. Deoxygenated blood is drained from the IVC and SVC, and then returned to the right atrium.
References
1. http://www.smartcanula.com/
2. Eur J Cardiothorac Surg. 2009 Oct;36(4):665-9
3. http://www.avalonlabs.com/html/pulmonary_support.html