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Overcrowding
Essentials
- 1
Overcrowding is the situation where emergency department (ED) function is impeded primarily by the excessive number of patients needing or receiving care.
- 2
Access block is excessive delay in accessing appropriate inpatient beds and, in Australasia, is defined as the proportion of patients with longer than 8 hours total ED time.
- 3
Access block is the principal cause of overcrowding but overall demand is also increasing.
- 4
Although multiple different definitions have been used in studying overcrowding and access block, there is clear evidence that both are associated with diminished quality of care and worse patient outcomes including mortality.
- 5
Changes to ED structure and function including senior staffing, increased size, fast-track observation units and multidisciplinary discharge procedures can to some extent improve the function of the ED in the face of overcrowding, but do not address the underlying causes and are easily overwhelmed by increasing access block.
- 6
The causes of overcrowding and hence the solutions lie largely outside the ED and require a hospital-wide response, especially in managing hospital bed stock in such a way that inpatient beds remain available.
Introduction
Wherever human beings gather there are fluctuations in number and, without outside control, numbers occasionally exceed the efficient maximum for a given purpose. Emergency departments (EDs) are designed largely for ongoing flow of patients rather than gathering, but even in systems designed purely for flow (such as roads) there are peaks and troughs of activity and occupancy sometimes exceeds the number able to move safely and smoothly.
Overcrowding to the point of dysfunction has gradually become the norm in Australasian EDs and has been widely reported since the mid-1990s. The greatest contributing factor has been access block, the inability of patients requiring inpatient admission to access appropriate beds in a timely fashion, a phenomenon which is generally called ‘boarding’ in North America. There has additionally been increase in demand on EDs in both number and complexity of patients resulting from the enlarging, ageing population, the growth in diagnostic and therapeutic choices and changing expectations of medical availability and service. This has not been matched by growth in other services, especially outside office hours, increasing the burden on EDs.
Theoretical basis of overcrowding
Queuing theory indicates that the length of a queue and hence the waiting time to treatment is determined by the arrival rate, the treatment rate and the baulk rate (did not wait to be seen rate, which is usually dependent on the length of the queue). An individual patient’s access to emergency care is dependent first on their urgency (assuming the patient is triaged to the correct queue), secondly on the number of similar patients already waiting ahead and thirdly, on the rate and strategy of treatment. Treatment rate is dependent on staffing and on the number of patients already being treated (occupancy), which determines physical availability of resources and the competing demands on staff. On a daily basis, patient flow is significantly dependent on occupancy because even a small decrease in treatment rate has a cumulative effect: it further increases the number waiting ahead of each new arrival.
EDs can be considered as overcrowded when normal pathways of clinical care cannot be followed due to total patient load, that is, the treatment rate is reduced or the treatment quality suffers. Some authorities believe that an ED can be purely overcrowded with patients waiting to be seen while the treatment function remains optimal; others regard this situation as a ‘surge’—a subset of disaster medicine, rather than an overcrowding problem.
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