出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/11/23 13:34:27」(JST)
An emergency department (ED), also known as an accident & emergency department (A&E), emergency room (ER) or casualty department, is a medical treatment facility specializing in emergency medicine, the acute care of patients who present without prior appointment; either by their own means or by that of an ambulance. The emergency department is usually found in a hospital or other primary care center.
Due to the unplanned nature of patient attendance, the department must provide initial treatment for a broad spectrum of illnesses and injuries, some of which may be life-threatening and require immediate attention. In some countries, emergency departments have become important entry points for those without other means of access to medical care.
The emergency departments of most hospitals operate 24 hours a day, although staffing levels may be varied in an attempt to reflect patient volume.
In addition to the normal hospital based emergency departments a new trend has developed in states of Texas, Colorado and few other states where the emergency department is not attached to the hospital and is independent of the hospital. These new emergency departments are referred to as free standing emergency departments. Since free standing emergency departments are able to operate outside of hospital policies that lead to increased wait times, free standing emergency departments have much shorter wait times and over all better patient satisfaction. Texas has more free standing ERs than any other state. See Advance ER web site in Texas for more info on FSED
Accident services were already provided by workmen's compensation plans, railway companies, and municipalities in Europe and the United States by the late mid-nineteenth century, but the first specialized trauma care center in the world was opened in 1911 in the United States at the University of Louisville Hospital in Louisville, Kentucky, and was developed by surgeon Arnold Griswold during the 1930s. Griswold also equipped police and fire vehicles with medical supplies and trained officers to give emergency care while en route to the hospital.[1][2][3]
Today, a typical hospital has its emergency department in its own section of the ground floor of the grounds, with its own dedicated entrance. As patients can present at any time and with any complaint, a key part of the operation of an emergency department is the prioritization of cases based on clinical need. This process is called triage.
Triage is normally the first stage the patient passes through, and consists of a brief assessment, including a set of vital signs, and the assignment of a "chief complaint" (e.g. chest pain, abdominal pain, difficulty breathing, etc.). Most emergency departments have a dedicated area for this process to take place, and may have staff dedicated to performing nothing but a triage role. In most departments, this role is fulfilled by a nurse, although dependent on training levels in the country and area, other health care professionals may perform the triage sorting, including paramedics or physicians. Triage is typically conducted face-to-face when the patient presents, or a form of triage may be conducted via radio with an ambulance crew; in this method, the paramedics will call the hospital's triage center with a short update about an incoming patient, who will then be triaged to the appropriate level of care.
Most patients will be initially assessed at triage and then passed to another area of the department, or another area of the hospital, with their waiting time determined by their clinical need. However, some patients may complete their treatment at the triage stage, for instance if the condition is very minor and can be treated quickly, if only advice is required, or if the emergency department is not a suitable point of care for the patient. Conversely, patients with evidently serious conditions, such as cardiac arrest, will bypass triage altogether and move straight to the appropriate part of the department.
The resuscitation area, commonly referred to as "Trauma" or "Resus", is a key area in most departments. The most seriously ill or injured patients will be dealt with in this area, as it contains the equipment and staff required for dealing with immediately life-threatening illnesses and injuries. Typical resuscitation staffing involves at least one attending physician, and at least one and usually two nurses with trauma and Advanced Cardiac Life Support training. These personnel may be assigned to the resuscitation area for the entirety of the shift, or may be "on call" for resuscitation coverage (i.e. if a critical case presents via walk-in triage or ambulance, the team will be paged to the resuscitation area to deal with the case immediately). Resuscitation cases may also be attended by residents, radiographers, ambulance personnel, respiratory therapists, hospital pharmacists and/or students of any of these professions depending upon the skill mix needed for any given case and whether or not the hospital provides teaching services.
Patients who exhibit signs of being seriously ill but are not in immediate danger of life or limb will be triaged to "acute care" or "majors," where they will be seen by a physician and receive a more thorough assessment and treatment. Examples of "majors" include chest pain, difficulty breathing, abdominal pain and neurological complaints. Advanced diagnostic testing may be conducted at this stage, including laboratory testing of blood and/or urine, ultrasonography, CT or MRI scanning. Medications appropriate to manage the patient's condition will also be given. Depending on underlying causes of the patient's chief complaint, he or she may be discharged home from this area or admitted to the hospital for further treatment.
Patients whose condition is not immediately life-threatening will be sent to an area suitable to deal with them, and these areas might typically be termed as a prompt care or minors area. Such patients may still have been found to have significant problems, including fractures, dislocations, and lacerations requiring suturing.
Children can present particular challenges in treatment. Some departments have dedicated pediatrics areas, and some departments employ a play therapist whose job is to put children at ease to reduce the anxiety caused by visiting the emergency department, as well as provide distraction therapy for simple procedures.
Many hospitals have a separate area for evaluation of psychiatric problems. These are often staffed by psychiatrists and mental health nurses and social workers. There is typically at least one room for people who are actively a risk to themselves or others (e.g. suicidal).
Fast decisions on life-and-death cases are critical in hospital emergency rooms. As a result, doctors face great pressures to overtest and overtreat. The fear of missing something often leads to extra blood tests and imaging scans for what may be harmless chest pains, run-of-the-mill head bumps, and non-threatening stomach aches, with a high cost on the Health Care system.[4]
Emergency department became the recommended term[by whom?] when emergency medicine was recognised as a medical specialty, and hospitals and medical centres developed departments of emergency medicine to provide services. Other common variations include 'emergency ward,' 'emergency centre' or 'emergency unit'.
Historical terminology still exists across the English-speaking world, especially in vernacular usage. The previously accepted formal term 'Accident and Emergency' or 'A&E' is still the accepted term in the United Kingdom,[5] Commonwealth countries and the Republic of Ireland, as are earlier terms such as 'Casualty' or 'casualty ward', which continue to be used informally. The same applies to 'emergency room' or 'ER' in North America, originating when emergency facilities were provided in a single room of the hospital by the department of surgery.
Regardless of naming convention, there is a widespread usage of directional signage in white text on a red background across the world, which indicates the location of the emergency department, or a hospital with such facilities.
Signs on emergency departments may contain additional information. In some American states there is close regulation of the design and content of such signs. For example, California requires wording such as "Comprehensive Emergency Medical Service" and "Physician On Duty",[6] to prevent persons in need of critical care from presenting to facilities that are not fully equipped and staffed.
In some countries, including the United States and Canada, a smaller facility that may provide assistance in medical emergencies is known as a clinic. Larger communities often have walk-in clinics where people with medical problems that would not be considered serious enough to warrant an emergency department visit can be seen. These clinics often do not operate on a 24-hour basis. Very large clinics may operate as "free-standing emergency centres," which are open 24 hours and can manage a very large number of conditions. However, if a patient presents to a free-standing clinic with a condition requiring hospital admission, he or she must be transferred to an actual hospital, as these facilities do not have the capability to provide inpatient care.
Many US emergency departments are exceedingly busy. A study found that in 2009, there were an estimated 128,885,040 ED encounters in US hospitals. Approximately one-fifth of ED visits in 2010 were for patients under the age of 18 years.[7] In 2009–2010, a total of 19.6 million emergency department visits in the United States were made by persons aged 65 and over.[8] Most encounters (82.8 percent) resulted in treatment and release; 17.2 percent were admitted to inpatient care.[9]
Rates of ED visits rose between 2006 to 2011 for almost every patient characteristic and location. The total rate of ED visits increased 4.5% in that time. However, the rate of visits for patients under one year of age declined 8.3%.[10]
A survey of New York area doctors in February 2007 found that injuries and even deaths have been caused by excessive waits for hospital beds by ED patients.[11] A 2005 patient survey found an average ED wait time from 2.3 hours in Iowa to 5.0 hours in Arizona.[12]
One inspection of Los Angeles area hospitals by Congressional staff found the EDs operating at an average of 116% of capacity (meaning there were more patients than available treatment spaces) with insufficient beds to accommodate victims of a terrorist attack the size of the 2004 Madrid train bombings. Three of the five Level I trauma centres were on "diversion", meaning ambulances with all but the most severely injured patients were being directed elsewhere because the ED could not safely accommodate any more patients.[13] This controversial practice was banned in Massachusetts (except for major incidents, such as a fire in the ED), effective January 1, 2009; in response, hospitals have devoted more staff to the ED at peak times and moved some elective procedures to non-peak times.[14][15]
In 2009, there were 1,800 EDs in the country.[16] In 2011, about 421 out of every 1,000 people in the United States visited the emergency department; five times as many were discharged as were admitted.[17] Rural areas are the highest rate of ED visits (502 per 1,000 population) and large metro counties had the lowest (319 visits per 1,000 population). By region, the Midwest had the highest rate of ED visits (460 per 1,000 population) and Western States had the lowest (321 visits per 1,000 population).[17]
Most Common Reasons for Discharged Emergency Department Visits in the U.S., 2011[17]
| Age (in years) | Reason for Visit | Visits |
|---|---|---|
| <1 | Fever of unknown origin | 270,000 |
| 1-17 | Superficial injury, contusion | 1.6 million |
| 18-44 | Sprains and Strains | 3.2 million |
| 45-64 | Nonspecific chest pain | 1.5 million |
| 65-84 | Nonspecific chest pain | 643,000 |
| 85+ | Superficial injury, contusion | 213,000 |
All A&E departments throughout the United Kingdom are financed and managed publicly by the NHS of each constituent country (England, Scotland, Wales and Northern Ireland). As with most other NHS services, emergency care is provided to all, both resident citizens and those not ordinarily resident in the UK, free at the point of need and regardless of any ability to pay.
Historically, waits for assessment in A&E were very long in some areas of the UK. In October 2002, the Department of Health introduced a four-hour target in emergency departments that required departments in England to assess and treat patients within four hours of arrival, with referral and assessment by other departments if deemed necessary. It was expected that the patients would have physically left the department within the four hours. Present policy is that 95% of all patient cases do not "breach" this four-hour wait. The busiest departments in the UK outside London include University Hospital of Wales in Cardiff, The North Wales Regional Hospital in Wrexham, the Edinburgh Royal Infirmary and Queen Alexandra Hospital in Portsmouth.
The 4-hour target triggered the introduction of the acute assessment unit (also known as the medical assessment unit), which works alongside the emergency department but is outside it for statistical purposes in the bed management cycle. It is claimed that though A&E targets have resulted in significant improvements in completion times, the current target would not have been possible without some form of patient re-designation or re-labeling taking place, so true improvements are somewhat less than headline figures might suggest and it is doubtful that a single target (fitting all A&E and related services) is sustainable.[18]
Although the four-hour target helped to bring down waiting times when it was first introduced, since September 2012 hospitals in England have struggled to stick to it, prompting suggestions that A&E departments may be reaching a limit in terms of what can be achieved within the available resources.[19] In July 2014, the QualityWatch research programme published in-depth analysis which tracked 41 million A&E attendances from 2010 to 2013.[20] This showed that the number of patients in a department at any one time was closely linked to waiting times, and that crowding in A&E had increased as a result of a growing and ageing population, compounded by the freezing or reduction of A&E capacity. Between 2010/11 and 2012/13 crowding increased by 8%, despite a rise of just 3% in A&E visits, and this trend looks set to continue. Other influential factors identified by the report included temperature (with both hotter and colder weather pushing up A&E visits), staffing and inpatient bed numbers.
A&E services in the UK are often the focus of a great deal of media and political interest, and data on A&E performance is published weekly.[21] However, this is only one part of a complex urgent and emergency care system. Reducing A&E waiting times therefore requires a comprehensive, coordinated strategy across a range of related services.[22]
Many A&E departments are crowded and confusing. Many of those attending are understandably anxious, and some are mentally ill, and especially at night are under the influence of alcohol or other substances. Pearson Lloyd's redesign - 'A Better A&E' - is claimed to have reduced aggression against hospital staff in the departments by 50 per cent. A system of environmental signage provides location-specific information for patients. Screens provide live information about how many cases are being handled and the current status of the A&E department.[23]
Cardiac arrest may occur in the ED/A&E or a patient may be transported by ambulance to the emergency department already in this state. Treatment is basic life support and advanced life support as taught in advanced life support and advanced cardiac life support courses. This is an immediately life-threatening condition which requires immediate action in salvageable cases.
Patients arriving to the emergency department with a myocardial infarction (heart attack) are likely to be triaged to the resuscitation area. They will receive oxygen and monitoring and have an early ECG; aspirin will be given if not contraindicated or not already administered by the ambulance team; morphine or diamorphine will be given for pain; sub lingual (under the tongue) or buccal (between cheek and upper gum) glyceryl trinitrate (nitroglycerin) (GTN or NTG) will be given, unless contraindicated by the presence of other drugs, such as drugs that treat erectile dysfunction.
An ECG that reveals ST segment elevation or new left bundle branch block suggests complete blockage of one of the main coronary arteries. These patients require immediate reperfusion (re-opening) of the occluded vessel. This can be achieved in two ways: thrombolysis (clot-busting medication) or percutaneous transluminal coronary angioplasty (PTCA). Both of these are effective in reducing significantly the mortality of myocardial infarction. Many centers are now moving to the use of PTCA as it is somewhat more effective than thrombolysis if it can be administered early. This may involve transfer to a nearby facility with facilities for angioplasty.
Major trauma, the term for patients with multiple injuries, often from a road traffic accident or a major fall, is initially handled in the Emergency Department. However, trauma is a separate (surgical) specialty from emergency medicine (which is a medical specialty, and has certifications in the United States from the American Board of Emergency Medicine).
Trauma is treated by a trauma team who have been trained using the principles taught in the internationally recognized Advanced Trauma Life Support (ATLS) course of the American College of Surgeons. Some other international training bodies have started to run similar courses based on the same principles.
The services that are provided in an emergency department can range from x-rays and the setting of broken bones to those of a full-scale trauma centre. A patient's chance of survival is greatly improved if the patient receives definitive treatment (i.e. surgery or reperfusion) within one hour of an accident (such as a car accident) or onset of acute illness (such as a heart attack). This critical time frame is commonly known as the "golden hour".
Some emergency departments in smaller hospitals are located near a helipad which is used by helicopters to transport a patient to a trauma centre. This inter-hospital transfer is often done when a patient requires advanced medical care unavailable at the local facility. In such cases the emergency department can only stabilize the patient for transport.
Some patients arrive at an emergency department for a complaint of mental illness. In many jurisdictions (including many US states), patients who appear to be mentally ill and to present a danger to themselves or others may be brought against their will to an emergency department by law enforcement officers for psychiatric examination. The emergency department conducts medical clearance rather than treats acute behavioral disorders. From the emergency department, patients with significant mental illness may be transferred to a psychiatric unit (in many cases involuntarily).
Acute exacerbations of chronic respiratory diseases, mainly asthma and chronic obstructive pulmonary disease (COPD), are assessed as emergencies and treated with oxygen therapy, bronchodilators, steroids or theophylline, have an urgent chest X-ray and arterial blood gases and are referred for intensive care if necessary. Noninvasive ventilation in the ED has reduced the requirement for tracheal intubation in many cases of severe exacerbations of COPD.
An ED requires different equipment and different approaches than most other hospital divisions. Patients frequently arrive with unstable conditions, and so must be treated quickly. They may be unconscious, and information such as their medical history, allergies, and blood type may be unavailable. ED staff are trained to work quickly and effectively even with minimal information.
ED staff must also interact efficiently with pre-hospital care providers such as EMTs, paramedics, and others who are occasionally based in an ED. The pre-hospital providers may use equipment unfamiliar to the average physician, but ED physicians must be expert in using (and safely removing) specialized equipment, since devices such as military anti-shock trousers ("MAST") and traction splints require special procedures. Among other reasons, given that they must be able to handle specialized equipment, physicians can now specialize in emergency medicine, and EDs employ many such specialists.
ED staff have much in common with ambulance and fire crews, combat medics, search and rescue teams, and disaster response teams. Often, joint training and practice drills are organized to improve the coordination of this complex response system. Busy EDs exchange a great deal of equipment with ambulance crews, and both must provide for replacing, returning, or reimbursing for costly items.
Cardiac arrest and major trauma are relatively common in EDs, so defibrillators, automatic ventilation and CPR machines, and bleeding control dressings are used heavily. Survival in such cases is greatly enhanced by shortening the wait for key interventions, and in recent years some of this specialized equipment has spread to pre-hospital settings. The best-known example is defibrillators, which spread first to ambulances, then in an automatic version to police cars, and most recently to public spaces such as airports, office buildings, hotels, and even shopping malls.
Because time is such an essential factor in emergency treatment, EDs typically have their own diagnostic equipment to avoid waiting for equipment installed elsewhere in the hospital. Nearly all have radiographic examination rooms staffed by dedicated radiographers, and many now have full radiology facilities including CT scanners and ultrasonography equipment. Laboratory services may be handled on a priority basis by the hospital lab, or the ED may have its own "STAT Lab" for basic labs (blood counts, blood typing, toxicology screens, etc.) that must be returned very rapidly.
Metrics applicable to the ED can be grouped into three main categories, volume, cycle time, and patient satisfaction. Volume metrics including arrivals per hour, percentage of ED beds occupied and age of patients are understood at a basic level at all hospitals as an indication for staffing requirements. Cycle time metrics are the mainstays of the evaluation and tracking of process efficiency and are less widespread since an active effort is needed to collect and analyze this data. Patient satisfaction metrics, already commonly collected by nursing groups, physician groups and hospitals, are useful in demonstrating the impact of changes in patient perception of care over time. Since patient satisfaction metrics are derivative and subjective, they are less useful in primary process improvement. Health information exchanges can reduce nonurgent ED visits by supplying current data about admissions, discharges, and transfers to health plans and accountable care organizations, allowing them to shift ED use to primary care settings.[24]
In all Primary Care Trusts there are out of hours medical consultations provided by general practitioners or nurse practitioners.
In the United States, and many other countries, hospitals are beginning to create areas in their emergency rooms for people with minor injuries. These are commonly referred as Fast Track or Minor Care units. These units are for people with non-life-threatening injuries. The use of these units within a department have been shown to significantly improve the flow of patients through a department and to reduce waiting times. Urgent care clinics are another alternative, where patients can go to receive immediate care for non-life-threatening conditions. To reduce the strain on limited ED resources, American Medical Response created a checklist that allows EMTs to identify intoxicated individuals who can be safely sent to detoxification facilities instead.[25]
Emergency department overcrowding is when function of a department is hindered by an inability to treat all patients in an adequate manner. This is a common occurrence in emergency departments worldwide.[26] Overcrowding causes inadequate patient care which leads to poorer patient outcomes.[26][27] To address this problem, Lakeland Regional Medical Center successfully implemented several techniques in 2011 to improve emergency department efficiencies. The emergency department reorganized space into pods, made staffing changes to facilitate patient flow, required emergency medical service personnel to provide advance notice of ambulance arrivals so that a bed could be preassigned, and had a multidisciplinary team develop and use care plans for nonemergent patients who repeatedly present with chronic pain issues.[28]
Emergency department (ED) waiting times have a serious impact on patient mortality, morbidity with readmission in less than 30 days, length of stay, and customer satisfaction. A review of the literature bears out the logical premise that since the outcome of treatment for all diseases and injuries is time-sensitive, the sooner treatment is rendered, the better the outcome.[29][30] Various studies reported significant associations between waiting times and higher mortality and morbidity among those who survived.[31] It is clear from the literature that untimely hospital deaths and morbidity can be reduced by reductions in ED waiting times.[32]
Waiting times are drastically reduced in what is referred to as a free standing emergency department. Free standing emergency departments are not attached to a hospital, so they are not incumbered by hospital policies that lead to long wait times in a hospital,based ER setting
Frequent presenters are persons who will present themselves at a hospital multiple times, usually those with complex medical requirements or with psychological issues complicating medical management.[33] These persons contribute to overcrowding and typically require more hospital resources although they do not account for a significant amount of visits.[34] To help prevent inappropriate emergency department use and return visits, some hospitals offer care coordination and support services such as at-home and in-shelter transitional primary care for frequent presenters and short-term housing for homeless patients recovering after discharge.[35][36]
Emergency departments in the military benefit from the added support of enlisted personnel who are capable of performing a wide variety of tasks they have been trained for through specialized military schooling. For example, in United States Military Hospitals, Air Force Aerospace Medical Technicians and Navy Hospital Corpsmen perform tasks that fall under the scope of practice of both doctors (i.e. sutures, staples and incision and drainages) and nurses (i.e. medication administration, foley catheter insertion, and obtaining intravenous access) and also perform splinting of injured extremities, nasogastric tube insertion, intubation, wound cauterizing, eye irrigation, and much more. Often, some civilian education and/or certification will be required such as an EMT certification, in case of the need to provide care outside the base where the member is stationed. The presence of highly trained enlisted personnel in an Emergency Departments drastically reduces the workload on nurses and doctors.
According to a survey at an urban inner-city tertiary care centre in Vancouver,[37] 57% of health care workers were physically assaulted in 1996. 73% were afraid of patients as a result of violence, almost half, 49%, hid their identities from patients, 74% had reduced job satisfaction. Over one-quarter of the respondents took days off because of violence. Of respondents no longer working in the emergency department, 67% reported that they had left the job at least partly owing to violence. Twenty-four hour security and a workshop on violence prevention strategies were felt to be the most useful potential interventions. Physical exercise, sleep and the company of family and friends were the most frequent coping strategies.[37]
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