Comparison of two different blood pumps on delivery of gaseous microemboli during pulsatile and nonpulsatile perfusion in a simulated infant CPB model.

The purpose of this study was to compare two different blood pumps (Jostra roller pump vs. Medos deltastream DP1 rotary pump) on delivery of gaseous microemboli during pulsatile and nonpulsatile perfusion in a simulated infant cardiopulmonary bypass (CPB) model. The Jostra and Medos pump were used in parallel pattern. The circuit was primed with lactated ringer's solution (700 ml) and the postfilter pressure was maintained at 100 mm Hg. Three transducers (postpump, postoxygenator and postfilter sites) of the Emboli Detection and Classification (EDAC) Quantifier were inserted into the CPB circuit to detect and classify gaseous microemboli. Trials were conducted at flow rates ranging from 500 to 1250 ml/min (250 ml/min increments). The arterial filter purge line was kept open during all trials. After injecting 20 ml air into the venous line, 2-minute segments of data were recorded simultaneously through three transducers. This entire process was repeated six times for each unique combination of blood pump, flow rate and perfusion mode, yielding a total of 96 experiments. Independent of perfusion mode and flow rate, Medos pump delivered less gaseous microemboli than Jostra pump at the postpump site, but only at 1,250 ml/min of pump flow rate the differences reached statistical significance (p < 0.01). There was no difference in delivery at the postfilter site. Compared with nonpulsatile flow, pulsatile flow transferred significantly more gaseous microemboli at the postpump site at 1,250 ml/min of pump flow rate in both groups (p < 0.01). The majority of gaseous microemboli were trapped by the membrane oxygenator. The results of this study confirm that rotary pump could deliver less gaseous microemboli than roller pump at the postpump site when a fixed volume air was introduced into the venous line. Pulsatile flow could transfer more gaseous microemboli at the postpump site, no matter which blood pump was used. Only few gaseous microemboli appeared at the postfilter site at high flow rates with an open arterial filter purge line.