The purpose of this work was to analyze the causes of the increasing number of hospital-related incidents in Region Västra Götaland of Sweden and their impacts on the prehospital and hospital preparedness in case of major incidents. In our study the alert is initiated by the affected ED requesting the EMS dispatch centre to divert patients transported by ambulance to other EDs. One limitation to this study is the lack of possibility to measure the impact of ambulance diversions on individual patients or patients groups. The main cause of hospital-related incidents in this report was labeled as ED-overcrowding. There is however no universal definition for ED-overcrowding, as each hospital might have its own definition.
Disasters seldom occur, but if they strike a fast and effective response from healthcare services is expected. An increasing number of reports on incidents when emergency hospitals, for different reasons, cannot operate at their normal capacity are a matter of concern for patient safety as well as disaster response preparedness . In the available literature hospital bed shortage and ED downsizing are reported to be some of the causes of ED-overcrowding leading to impaired responsiveness and ambulance diversions [4, 6, 8, 9, 11, 12]. In our study, we could also show that hospital bed shortage and technical dysfunction at radiology departments, beside the increasing number of patients at EDs are the main reasons for ED-overcrowding in our region. Our findings (Table 1, Figure 1) are consistent with those earlier reported. Like in many other parts of the world, reduction of hospital beds and corresponding staff in combination with increasing number of out-patients treatments and coordination of activities between nearly located hospitals, have been some of the solutions to handle the economical constrain on the healthcare systems [9, 11, 13]. The mean length of hospital stay (LOS) has been reduced in Sweden, as well as other Scandinavian countries, having the lowest LOS worldwide [5, 14]. Although these measures all seem to be logical steps taken to improve healthcare effectiveness and reducing the costs, they also, in a negative way, affect the surge capacity of a hospital. Such capacity in hospitals is necessary for proper management of extraordinary incidents and is influenced by 3 essential elements; staff, supplies/equipment, and structure [15, 16]. Structure refers to both location for patients and the organizational infrastructure. A key to a successful major incidents response of a hospital is an ED that is able to effectively sort (triage) the casualties, continue or start lifesaving treatment and rapidly transfer patients to facilities for definitive treatment within the hospital. If this key function is overcrowded already at the onset of a disaster response, the outcome for the patients will be suboptimal. It is already reported that ED-overcrowding is associated with both space and staff shortage [4, 7, 17, 18].
Hospital bed occupancy of ≥ 90% has been shown to correlate with a blocked access to the wards, defined as patients waiting in the ED for more than 8 h when the decision has been made to admit them [4, 19–21]. For severely ill patients this consequently leads to initiation of extra measures e.g.multiple testing, interventions and administration of drugs during their prolonged stay in the ED [4, 7, 19, 20]. In such situations the ED serves as a holding area for admitted patients, sometimes remaining for more than 24 h, due to the lack of beds . This even includes patients in need of beds at the intensive care units. Earlier reports indicate that the average waiting time for an inpatient acute or critical care bed in the USA EDs has nearly been doubled (> 6 h) in hospital with consistently overcrowded ED. The results, besides missed diagnoses, poor outcomes, prolonged pain and suffering for some patients, long waiting times, patient dissatisfaction, more ambulance diversions, lower physician and staff productivity and higher levels of frustration among medical staff, are higher hospital costs and longer LOS [2, 11–13, 21].
In addition many patients in the early time period of their diseases may leave ED due to long waiting time, without treatment. Curable disease may then become more critical and incurable when they return . Delay of > 6 h in bringing ED patients in critical condition to intensive care unit has also shown to increase hospital LOS and result in higher intensive care unit and hospital mortality .
Long-lasting hospital closure are associated with significant but temporary increase in ambulance diversions to the nearest ED. Fewer EDs and increasing number of patient visits over time, may also cause ED-overcrowding and consequent ambulance diversions [9, 22]. Ambulance diversion has a huge impact on public health, since it may place the patient at risk for poor outcome, prolonged pain and suffering. Ambulance diversion results in increasing transport time between hospitals, delayed treatments and may also increase mortality in severely injured trauma patients [7, 9, 22]. It also results in significant loss of hospital revenue due to the throughput delays that prevent the use of existing bed capacity for additional patient admissions 
In conclusion hospital-related incidents are by no means extraordinary incidents, but part of the ordinary shortcoming of the healthcare system caused, among others, by reduction in number of hospital beds, downsizing and/or closure of hospitals EDs. Such measures results in overcrowding of EDs and ambulance diversions. They also endanger patient's safety and may increase in-hospital mortality. It counteracts medical preparedness by minimizing the surge capacity. In the context of disaster preparedness this problem must be further studied and properly addressed by our political decision makers .