Medical Informatics has become an important tool in modern health care practice and research. In the present article we outline the challenges and opportunities associated with the implementation of electronic medical records (EMR) in complex environments such as intensive care units (ICU). We share our initial experience in the design, maintenance and application of a customized critical care, Microsoft SQL based, research warehouse, ICU DataMart. ICU DataMart integrates clinical and administrative data from heterogeneous sources within the EMR to support research and practice improvement in the ICUs. Examples of intelligent alarms -- "sniffers", administrative reports, decision support and clinical research applications are presented.