HIGH-FLOW LOW-RESISTANCE CANNULAS FOR PERCUTANEOUS ARTERIOVENOUS CARBON-DIOXIDE REMOVAL

Percutaneous cannulas with low resistance are necessary for arterioven ous carbon dioxide removal (AVCO(2)R) 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 pressur e/flow characteristics under conditions that simulated percutaneous AV CO(2)R at clinically pertinent flow rates between 200-1000 ml/min to o btain the M number previously described by Delius, et al. The Bio-Medi cus (Bio-Medicus, Grand Rapids, MI) 17F A, Research Medical, Inc (RMI) (Model FEM II, Research Medical, Int., Midvale, UT) 16F A, and RMI 18 F V cannulas exhibited the lowest M numbers that correlated with low r esistance to flow. The four most clinically favorable arterial cannula s (8, 10, 12, and 14 Fr), coupled with a venous cannula four French si zes larger, were used in an AVCO(2)R 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, a t 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, respecti vely. In summary, an arterial percutaneous cannula of 10 Fr or larger will allow AVCO(2)R blood flow greater than 500 ml/min, as previously shown by Brunston ct al. to achieve total CO2 removal without incurrin g hypercapnia.