Table 1.

Properties of complex systems relevant to healthcare

Property	Description
Poorly defined boundaries with other systems	Other hospitals, ambulance trusts, community services influence the functioning of an individual hospital. Healthcare is an open system in which external agents (regulators, media, social care policy, weather, pandemics) can influence its functioning.
Membership can change and members can have membership of more than one system	Within anaesthesia and intensive care this is apparent with rotational and temporary staff, unfamiliar anaesthetists working across different external teams and potentially at very short notice (interventional radiology, endoscopy).
Dispersed and decentralised control	Decisions are made constantly by individual agents. An ICU may have different protocols and policies to the rest of a hospital for certain circumstances or conditions (e.g. cardiac arrest, medication practices). Clinicians have autonomy to deviate from policy to accommodate patient complexity and uncertainty.