Delivery of Gaseous Microemboli With Vacuum-Assisted Venous Drainage During Pulsatile and Nonpulsatile Perfusion in a Simulated Neonatal Cardiopulmonary Bypass Model

UNDAR*‡§ This study investigated delivery of gaseous microemboli (GME) with vacuum-assisted venous drainage (VAVD) at various flow rates and perfusion modes in a simulated neonatal cardiopulmonary bypass (CPB) model. Four transducers (postpump, postoxygenator, postfilter, and venous line) of the emboli detection and classification (EDAC) quantifier were inserted into the CPB circuit to detect and classify GME. Four negative pressures (0, 15, 30, and 45 mm Hg), 3 flow rates (750, 1,000, and 1,250 ml/min), and 2 perfusion modes (pulsatile and nonpulsatile) were tested. After injecting 10 ml air into the venous line via an 18G needle, 2-minute segments of data were recorded simultaneously through 4 transducers. This entire process was repeated 6 times for each unique combination of pressure, flow rate, and perfusion mode, yielding a total of 144 experiments. Independent of perfusion mode and flow rate, the use of VAVD with higher negative pressures delivered significantly more GME at the postpump site. There was no difference in delivery at the postfilter site. The majority of GME were trapped by the Capiox Baby-RX hollow-fiber membrane oxygenator. Compared with nonpulsatile flow, pulsatile flow transferred more GME at the postpump site at all 3 flow rates. Our results suggest that VAVD with higher negative pressures, increased flow rates, and pulsatile flow could deliver more GME at the postpump site when a fixed volume air is introduced into the venous line. The Emboli Detection and Classification Quantifier is a sensitive tool for the detection and classification of GME as small as 10 microns in this simulated neonatal model. ASAIO Journal 2008; 54:416‐422.