Biomedical Instrumentation design is oriented toward a new generation of devices that have greater autonomy and possibilities of giving more interpreted results and for this reason are called Intelligent Instruments. In this work an overview of the general problems involved in monitoring and management of critical care patients is given, along with the description of a prototype knowledge-based system for senous arrhythmia management. Finally, a discussion of some of the open questions that must be answered is presented. The experience gained in the progress of this work, specially with real life applications has given considerable insight for facing the realistic and practical design of state-of-the-art critical care environment instrumentation.