**3. Pulse Push/Pull Hemodialysis (PPPHD)**

Flow patterns, that is, pulsatile versus non-pulsatile, remain topics of research for treatments requiring extracorporeal blood circulation. Despite controversy, blood pulsation has been accepted to have a benefit during cardiopulmonary bypass, because it achieves greater perfusion to peripheral vessels and end-organs (Dapper et al., 1992, Orime et al., 1999). Furthermore, blood pulsation in a pediatric CRRT1 animal model was found to deliver adequate performance over a 2-hour period in terms of ultrafiltration rates and cross-filter blood pressure drops (Lopez-Herce et al., 2006, Ruperez et al., 2003). In addition, it was also found that the pulsatile flow tends to enhance ultrafiltration rates versus non-pulsatile flow (Lim et al., 2009, Runge et al., 1993), which attributed to an increased rheological power of pulsatile flow. However, little clinical or experimental evidence is available that explains the efficacy of pulsatile flow during dialysis. Pulse push/pull HD is a convection enhanced dialysis treatment, based on the use of pulsatile flows to achieve a cyclic repetition of forward and backward filtration. As explained in the previous section, the repetitive manner of ultrafiltration and backfiltration contributes substantially to total volume exchange and convective mass transfer.
