High flow/low resistance cannulas for percutaneous arteriovenous carbon dioxide removal

Percutaneous cannulas with low resistance are necessary for arteriovenous carbon dioxide removal (AVCO2R) to allow highest flow at lowest pressure to maximize CO2 removal. Commercially available arterial (A) and venous (V) percutaneous cannulas (8-18 Fr) were tested for pressure/flow characteristics under conditions that simulated percutaneous AVCO2R at clinically pertinent flow rates between 200-1000 ml/min to obtain the M number previously described by Delius, et al. The Bio-Medicus (Bio-Medicus, Grand Rapids, MI) 17F A, Research Medical, Inc (RMI) (Model FEM II, Research Medical, Inc., Midvale, UT) 16F A, and RMI 18F V cannulas exhibited the lowest M numbers that correlated with low resistance to flow. The four most clinically favorable arterial cannulas (8, 10, 12, and 14 Fr), coupled with a venous cannula four French sizes larger, were used in an AVCO2R circuit in adult sheep (n = 3) at varying mean arterial pressures (MAP) between 65-105 mmHg. The 8, 10, 12, and 14 Fr arterial cannulas allowed an arteriovenous flow of 208 +/- 72, 530 +/- 37, 848 +/- 66, and 944 +/- 96 ml/min, respectively, at a MAP of 65 mmHg. An increase in MAP to 105 mmHg was associated with approximately a 41, 30, 32, and 27% increment in blood flow, respectively. In summary, an arterial percutaneous cannula of 10 Fr or larger will allow AVCO2R blood flow greater than 500 ml/min, as previously shown by Brunston et al. to achieve total CO2 removal without incurring hypercapnia.