A Performance Evaluation of Eight Geometrically Different 10 Fr Pediatric Arterial Cannulae Under Pulsatile and Nonpulsatile Perfusion Conditions in an Infant Cardiopulmonary Bypass Model

Abstract

This investigation compared pressure drops and surplus hemodynamic energy (SHE) levels in eight commercially available pediatric aortic cannulae (10 Fr) with different geometries during pulsatile and nonpulsatile perfusion conditions in an in vitro infant model of cardiopulmonary bypass. For each trial, the cannula was placed at the distal end of the arterial line, and the insertion tip was fixed to the inlet of the simulated patient. The pseudo patient was subjected to seven pump flow rates ranging from 400 to 1000 ml/min (at 100 ml/min increments), and the mean arterial pressure was set at a constant 40 mm Hg via Hoffman clamp. Of the eight cannulae, the Surgimedics and THI models had significantly larger pressure drops (48.8 +/- 0.3 mm Hg and 48.3 +/- 1.4 mm Hg, respectively; 600 ml/min pulsatile) compared with the RMI cannula (27.6 +/- 1.2 mm Hg; 600 ml/min pulsatile), which created, on average, half of the pressure drop seen in the poorest performing cannulae. When perfusion mode was switched from nonpulsatile to pulsatile, there was a 7-9 fold increase in delivery of SHE recorded at both the pre- and postcannulae sites, regardless of which cannula was being tested. Despite being classified under the same size (10 Fr), these eight cannulae were found to vary considerably in length, inner diameter, and geometrical design. The results suggest that these differences can have a significant impact on pressure drops, as well as generation and delivery of SHE. Furthermore, it was found that pulsatile perfusion produced more "extra" hemodynamic energy when compared with nonpulsatile perfusion, regardless of cannula model.