THE TYPE OF AORTIC CANNULA AND MEMBRANE-OXYGENATOR AFFECT THE PULSATILE WAVE-FORM MORPHOLOGY PRODUCED BY A NEONATE-INFANT CARDIOPULMONARY BYPASS SYSTEM IN-VIVO

Although the debate still continues over the effectiveness of pulsatil e versus nonpulsatile perfusion, it has been clearly proven that there are several significant physiological benefits of pulsatile perfusion during cardiopulmonary bypass (CPB) compared to nonpulsatile perfusio n. However, the components of the extracorporeal circuit have not been fully investigated regarding the quality of the pulsatility. In addit ion, most of these results have been gathered from adult patients, not from neonates and infants. We have designed and tested a neonate-infa nt pulsatile CPB system using 2 different types of 10 Fr aortic cannul as and membrane oxygenators in 3 kg piglets to evaluate the effects of these components on the pulsatile waveform produced by the system. In terms of the methods, Group 1 (Capiox 308 hollow-fiber membrane oxyge nator and DLP aortic cannula with a very short 10 Fr tip [n = 2]) was subjected to a 2 h period of normothermic pulsatile CPB with a pump fl ow rate of 150 ml/kg/min. Data were obtained at 5, 30, 60, 90, and 120 min of CPB. In Group 2 (Capiox 308 hollow-fiber membrane oxygenator a nd Elecath aortic cannula with a very long 10 Fr tip [n = 7]) and Grou p 3 (Cobe VPCML Plus flat sheet membrane oxygenator and DLP aortic can nula with a very short 10 Fr tip [n = 7]), the subjects' nasopharyngea l temperatures were reduced to 18 degrees C followed by 1 h of deep hy pothermic circulatory arrest (DHCA) and then 40 min rewarming. Data we re obtained during normothermic CPB in the pre- and post-DHCA periods. The criteria of pulsatility evaluations were based upon pulse pressur e (between 30 and 40 mm Hg), aortic dp/dt (greater than 1000 mm Hg/s), and ejection time (less than 250 ms). The results showed that Group 1 produced flow which was significantly more pulsatile than that of the other 2 groups. Although the same oxygenator was used for Group 2, th e quality of the pulsatile flow decreased when using a different aorti c cannula. Group 3 did not meet any of the criteria for physiologic pu lsatility. In conclusion these data suggest that in addition to a puls atile pump, the aortic cannula and the membrane oxygenator must be cho sen carefully to achieve physiologic pulsatile now during CPB.