In the CRRT circuit, the highest pressure is the pre-filter pressure. This is because during the CRRT process, the blood passes through the blood pump before entering the filter. The pressure measurement point at this time is after the blood pump and before the filter, so the pressure at this position is the highest in the entire extracorporeal circulation system. The pre-filter pressure is related to factors such as blood pump flow, filter resistance, and resistance at the venous end of the vascular access. In actual operation, excessive increase in pre-filter pressure may cause problems such as cracking of the circulation pipeline joint, blood loss, or filter membrane rupture. Therefore, it is not only a pressure indicator, but also an important indicator for safety monitoring.