Is SHE Necessary? An Alternative Narrative

Lifesaving medical interventions, using extracorporeal circulation (ECC), have a high risk of organ injury. There is an argument that surplus haemodynamic energy (SHE) at physiological levels is required to reduce this injury. Currently, an ECC pump is used to mechanically circulate the blood, which is delivered in non-pulsatile perfusion (NPP) mode in most cases. The initial stance for this alternative narrative was that SHE is necessary, and that contemporary published research would support this argument. A long-running debate has been underway of if the use of pulsatile perfusion (PP) or NPP during ECC reduces inflammation and subsequent complications. The associated research has not always considered SHE levels that mimic physiological levels when PP was investigated. SHE is rarely mentioned when discussing ECC and often does not include physiological levels within the body. It has been argued that the results of published research are inconclusive because of the number of variables, lack of standardized inputs, differences in methodology, and the small sample sizes of the majority of research. Given the challenges in gaining approvals and conducting research during lifesaving interventions, these observations are not surprising. The change in vocabulary over time has also impacted on the capacity to review the research with similar parameters using different language. In some circumstances, there appears to be a reluctance to extend the conversation from PP to include physiological haemodynamics, energy equivalent pressure, and SHE.