• accreditation
• ambulatory care
• attitudes

Emergency department (ED) crowding has long been recognised as posing significant patient safety threats. Research has demonstrated ties between ED crowding and delays in time-sensitive, disease-specific interventions such as thrombolysis in patients with acute myocardial infarction1 and stroke,2 resuscitation in trauma patients,3 antibiotics for patients with community-acquired pneumonia,4 and more recently the timely treatment of patients with sepsis.5 Elderly patients in particular may be vulnerable to crowding.6 More broadly, it has become clear that periods of high ED crowding are associated with increased inpatient mortality, length of stay and costs,7 as well as decreased patient experience.8 9

Through health systems engineering, lean, and Six Sigma, ED leaders have sought to increase the efficiency of EDs, decrease crowding and improve the quality of care. Understanding the factors that contribute to ED crowding, including queuing theory, several solutions have been implemented to try to decompress crowded EDs.10 11 These ED solutions include matching the number of clinical shifts to expected patient arrival curves, positioning clinicians in triage,12 creating observation units,13 and streaming patients (split flow).12 Hospital system solutions have also been explored, including alternative pathways such as home hospital programmes,14 transferring lower acuity patients to partner community hospitals,15 smoothing the elective surgery schedule16 and boarding limited numbers of admitted ED patients in hospital hallways until a hospital bed becomes available.17 Over the years, groups like the Institute for Healthcare Improvement, American College of Emergency Physicians, and the …