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.