A quarter of the unintended events was related to the cooperation with other departments, e.g. with laboratories and nursing wards. In 20% of the unintended events, there were problems with materials or equipment. Furthermore, relatively large parts of unintended events were related to the collaboration

with resident physicians and consultants (17%) or to diagnosis and treatment (14%). Table 3 Types Inhibitors,research,lifescience,medical of unintended events Causes of unintended events All 522 unintended events were analysed with PRISMA, resulting in 845 root causes. Fifty percent of the unintended events had one root cause, 39% had two root causes, 10% three root causes and 1% four root causes. The mean number of root causes

per unintended event was 1.62 (SD = 0.71). In Figure ​Figure2,2, the distributions of the five main groups of root causes per event type are shown. Overall, most root causes were Inhibitors,research,lifescience,medical human (60%), followed by organisational (25%) and technical (11%) root causes. Unintended events related to materials and equipment were relatively often caused by technical factors. Incorrect data and substitutions were caused for a large part by human errors, while organisational factors contributed most to unintended events related to medical protocols and regulations. Figure Inhibitors,research,lifescience,medical 2 Distribution of main causal factor groups per unintended event type (N = 845). Table ​Table44 shows the frequencies of the causes Inhibitors,research,lifescience,medical on subcategory level (see also Table ​Table11 for explanation of the ECM categories). Material defects (TM) were the most common technical factors (38% of unintended events with technical causes). External factors were largely present, especially

human and organisational external factors (H-ex and O-ex). These are causes originating in another Inhibitors,research,lifescience,medical department outside the ED, e.g. the laboratory or radiology. Of all 845 root causes, 387 (46%) were external. In 69% of the unintended events with human causes, an external human factor contributed to the event, for example: the surgeon on duty was in the operating room and forgot to pass not the beeper to a fellow surgeon, or a laboratory worker forgot to insert a patient’s test results in the computer. In 58% of the unintended events with organisational causes, there was an external organisational factor, for example a laboratory worker saved blood pipes until the testing machine was full or a hospital admission stop was ignored by a medical consultant. Table 4 Causes of unintended events at the emergency department When looking at the internal causes inside the ED, human intervention errors (HRI) stand out (22% of unintended events with human causes). Examples of intervention errors are: not recording the time when medication was administered or not plugging the battery of a medical device in the socket.