Comparing dual-stream and standard cardiopulmonary bypass in pigs

Background. Dual-stream (DS) and standard cardiopulmonary bypass (CPB) were compared. Methods. A DS catheter inserted into the distal ascending aorta across the arch pumps blood through an upper lumen (maximum 2.25 L/min) directed by a blood-streaming baffle toward the arch vessels. A separate lower lumen pumps blood (maximum 3.75 L/min) into the aorta caudad to the inflated baffle. The baffle is flat and horizontal along the catheter. When the baffle is collapsed the heart or both lumens may perfuse all organs. For 30 minutes 8 randomized CPB pigs had corporeal cooling to 32°C and for 30 minutes had rewarming to 36°C. Eight randomized DS pigs had 25°C upper lumen cooling for 60 minutes. Lower lumen blood flow was streamed at 32°C for 30 minutes, then rewarmed to 36°C for 30 minutes. Results. The change in relative lower lumen to brain blood flow as determined by brain-counted microspheres (15 μ) injected into the ascending aorta was less for DS brains than controls during full flow (DS 63.4 ± 129.5 versus CPB 2,585.4 ± 250.8, p < 0.001), and when injected into the ejecting-heart left atrium just after weaning off only lower lumen blood flow (DS 250.8 ± 297.3 versus CPB 1,159.1 ± 782.3, p < 0.001). DS brain temperatures were lower at an equal pump-off core temperature of 36°C ± 0.5°C (DS 31.6°C ± 3.2°C versus CPB 36.5°C ± 1.7°C, p < 0.025). Jugular O2 saturations were not different. Conclusions. DS-CPB prioritizes pump-filtered separate cold blood flow to the brain over a blood-streaming baffle to wash away potentially surgery related air and particulate matter arising from the heart or ascending aorta.