This demo paper describes a clinical information system: Data Stream Engine based Clinical information system (DSEC). In DSEC, data stream technology as well as traditional computer mechanism is used to process medical data and improve the quality of service in hospitals. The novel features of DSEC include: 1) A complete data stream processing and querying architecture for medical application 2) being able to detect data changes in a simple and effective way; 3) a load shedding mechanism used to avoid system crash when high data rate occurs.