  Hospitals are complex systems and optimising their function is critical to
the provision of high quality, cost effective healthcare. Nevertheless, metrics
of performance have to date focused on the performance of individual elements
rather than the system as a whole. Manipulation of individual elements of a
complex system without an integrative understanding of its function is
undesirable and may lead to counter-intuitive outcomes and a holistic metric of
hospital function might help design more efficient services. We aimed to
characterise the system of peri-operative care for emergency surgical
admissions in our tertiary care hospital using network analysis. We used
retrospective electronic health record data to construct a weighted directional
network of the system. For this we selected all unplanned admissions during a
3.5 year period involving a surgical intervention during the inpatient stay and
obtained a set of 16,500 individual inpatient episodes. We then constructed and
analysed the structure of this network using established methods from network
science such as degree distribution, betweenness centrality and small-world
characteristics. The analysis showed the service to be a complex system with
scale-free, small-world network properties. This finding has implications for
the structure and resilience of the service as such networks, whilst being
robust in general, may be vulnerable to outages at specific key nodes. We also
identified such potential hubs and bottlenecks in the system based on a variety
of network measures. It is hoped that such a holistic, system-wide description
of a hospital service may provide better metrics for hospital strain and serve
to help planners engineer systems that are as robust as possible to external
shocks.
