Quantification of pressure-flow waveforms and selection of components for the pulsatile extracorporeal circuit

The debate on pulsatile flow during cardiopulmonary bypass (CPB) has continued for more than half a century. This longstanding debate stems from imprecise quantification methods for arterial pressure and pump flow waveforms and the inability to determine which waveforms accurately depict pulsatile flow. The differences in in vitro and in vivo research outcomes for pulsatile and non-pulsatile flow experiments compounds these issues. The concepts of energy equivalent pressure (EEP) and surplus hemodynamic energy (SHE) have been introduced in studies using pulsatile and nonpulsatile flow. Their main advantage lies in their focus on energy gradients rather than pressure gradients as the driving force of blood flow. These formulas can precisely quantify different levels of pulsatility and non-pulsatility, allowing direct and meaningful comparisons. In clinical practice, before using pulsatile flow during CPB, all components of CPB circuits, including the roller pump, membrane oxygenator, arterial filter, aortic cannula, and circuit tubing, should be carefully selected to ensure maximal pulsatility. In addition, it is necessary to select appropriate patients and durations for pulsatile perfusion to obtain better clinical effects. We hope results from our previous experiments can be used as a source of reference when using pulsatile flow in pediatric cardiac surgery.