The evolution of extracorporeal membrane oxygenation (ECMO) has led to an increasing reliance on objective parameters to detect complications early and enhance patient safety. One such parameter is the transmembrane pressure gradient, more commonly referred to as delta P (ΔP), the difference between the inlet and outlet pressures of the oxygenator. This measure has increasingly been recognized as a critical early indicator of thrombus formation within the oxygenator during ECMO support. However, its interpretation remains complex and context-dependent, particularly because delta P values are significantly influenced by the design features of different ECMO circuits, including pump head geometry and oxygenator configuration.