Relative and absolute blood flow values during cardiopulmonary bypass.

Blood fl ow (BF) management during cardiopulmonary bypass (CPB) is crucial for preventing injury to vital organs. The quantitative aspects of BF have been associated with cardiac index and body surface area and they are managed according to metabolic parameters, such as the relationship between delivery and oxygen consumption in relation to temperature, and hemodynamic parameters, such as mean arterial pressure. The qualitative aspects of BF are managed via different types of pumps (roller or centrifugal) with either a pulsed or continuous fl ow. However, the quantity and quality of BF measured during CPB weaning remain relative and not absolute specifying parameters, especially during the establishment and weaning phases of CPB, owing to the use of vents in the aortic root that sequesters BF or replenish bleeding via aspiration, which constitutes a theft of systemic fl ow. In such circumstances, the reintegration of the value stolen by endo-cavitary aspiration or bleeding (considered as a dynamic shunt to the circulation) is advisable. Inthis context, we read with great interest the article titled “ Pulsatile versus nonpulsatile blood fl ow during cardiopulmonary bypass ” by Chaney. In this interesting review, the author highlights the importance and advantages of pulsatile fl ow compared with non-pulsatile fl ow. Multiple studies that have evaluated the ef fi cacy of pulsatile fl ow during CPB have reported controversial results [1]. The suggested