Healthcare information systems play an important role in improving healthcare quality. As providing healthcare increasingly changes from isolated treatment episodes towards a continuous medical process involving multiple healthcare professionals and institutions, there is an obvious need for an information system to support processes and span the whole healthcare network. A suitable architecture for such an information system must take into account that it has to work as an integral part of a complex socio-technical system with changing conditions and requirements. We have surveyed the core requirements of healthcare professionals and analysed the literature for known problems and information needs. We consolidated the results to define use cases for an integrated information system as communication patterns, from which general implications on the required properties of a healthcare network information system could be derived. Key issues are flexibility, adaptability, robustness, in...