This article reports on the development of usability engineering recommendations for next-generation integrated interoperable medical devices. A model-based hazard analysis method is used to reason about possible design anomalies in interoperability functions that could lead to use errors. Design recommendations are identified that can mitigate design problems. An example application of the method is presented based on an integrated medical system prototype for postoperative care. The AAMI/UL technical committee used the results of the described analysis to inform the creation of the Interoperability Usability Concepts, Annex J, which is included in the first edition of the new ANSI/AAMI/UL 2800-1:2019 standard on medical device interoperability. The presented work is valuable to experts developing future revisions of the interoperability standard, as it documents key aspects of the analysis method used to create part of the standard. The contribution is also valuable to manufacturers, as it demonstrates how to perform a model-based analysis of use-related aspects of a medical system at the early stages of development, when a concrete implementation of the system is not yet available.