The ICU (intensive care unit) is easily one of a hospital’s highest value resources. A scarcity of intensive care beds means patients require prioritization when demand exceeds supply.  As a result, there are frequent delays in admission to an ICU. Though it is accepted that such delays adversely impact patient outcomes, there has been little data on the relationship between bed availability in an ICU and processes of care for patients who develop sudden clinical deterioration – especially in the context of an emergency department (ED). Recently, studies seeking to address this gap have provided renewed momentum to such discussions. They have also dovetailed with other efforts, such as specialist training in critical care for emergency medicine students and residents. However, the area generating maximum interest is a dedicated ICU within an emergency department.
Balancing needs, finding beds
Critically ill patients are commonplace in emergency medicine. They require aggressive and timely care, but emergency medicine clinicians have to balance their needs with those of other patients in their facility. In addition, due to constraints in beds in the ICU, increasing numbers of critically ill patients require to be boarded for prolonged periods of time in the ED. Adding to this problem is a shortage of beds in EDs too.
One of the most vexed questions is whether ED physicians consider bed availability in an ICU as part of their triage decisions, thereby impacting, in a potentially profound manner, on patient outcomes and resource utilization in both the ED and ICU. In effect, does a high availability of ICU beds lead to a bias in admission of patients who are either too well or too ill to benefit ? On the other side, does a low availability then lead to denying admission to ED patients, who would otherwise have been accepted to the ICU?

ED-ICU interface demands attention
In 2013, a study by the George Washington University School of Public Health and Health Sciences in Washington, DC, found that the volume of ICU admissions from EDs in the US had increased sharply, by almost 50 percent, in the period 2001-2009.¹ During this period, another study found that the number of ICU beds across the country had increased only 15%, from 67,579 to 77,809.²
In other words, it is clear that ICU admissions from EDs have been increasing at a faster rate than ED visits. The George Washington University study found that though lengths of mean ED and hospital stays had not changed significantly, the mean ICU admission spends over 5 hours in the ED prior to transfer to an ICU bed. As a result, its authors concluded, there was a need for more emphasis on the ED-ICU interface and for critical care delivered in the ED.

Training emergency physicians in the ICU
The roots of this complex combination of challenges go back several decades. One good example is a time-based study, published in 1993 in the peer-reviewed journal ‘Critical Care Medicine’.³  The authors, from Houston, Texas-based Methodist Hospital’s Department of Emergency Services, noted that not only did critically ill patients “constitute an important proportion of emergency department practice”, but also needed treatment in the ED “for significant periods of time.”  One of the solutions they proposed was for emergency medicine practitioners to “receive training in the continuing management of critically ill patients.”
The above approach was also witnessed in Europe. In Belgium, for example, an official paper from 1995, titled ‘How to become an intensivist’, proposes that a candidate with an “agreement in Emergency medicine has to make another year of ICU formation.”⁴

Pathways remained unclear
In subsequent years, there was significant growth in emergency medicine residents pursuing critical care fellowship training, and a reconsideration of the role played by the ED in caring for the critically ill. Nevertheless, there still was a lack of clarity in ways to acquire advanced training in critical care for emergency medicine residents.
In December 2002, an article in ‘Current Opinion in Critical Care’ complained that although ED care for critically ill patients was shown to significantly impact mortality, “formal critical care training for emergency physicians” was still “limited.”⁵
Less than three years later, another peer-reviewed journal, ‘Annals of Emergency Medicine’, noted that in spite of growing demand for critical care services, most critical care medicine fellowships did not accept emergency medicine residents, “and those who do successfully complete a fellowship do not have access to a US certification examination in critical care medicine.”⁶  The authors proposed “expansion of the J-1 visa waiver program for foreign medical graduates,” but said the only sensible long-term approach was to strengthen the relationship between emergency medicine and critical care medicine.

Critical care medicine as emergency medicine sub-specialty
In the US, the Accreditation Council for Graduate Medical Education (ACGME) approved critical care medicine as a sub-specialty for emergency medicine physicians in 2011. The following year, the surgical critical care fellowship pathway was approved for emergency physicians interested in becoming board-eligible intensivists.
Currently, the most common training pathways are via combinations of critical care medicine with internal medicine and anaesthesiology, and alongside surgical critical care and neurocritical care. Career pathways for physicians trained in emergency and critical care medicine are also evolving, with options in both community and academic settings.

The role of professional societies
Leading professional societies in emergency medicine and critical care have set up focused sections on the interface between the two areas to stimulate interest as well as provide support to medical students and residents.
Examples from the US include the Emergency Medicine Residents’ Association (EMRA), whose Critical Care Division maintains a comprehensive database of training opportunities across the country,⁷  and regularly publishes alerts on key developments in critical care. Another interesting initiative is the Coalition for Critical Care Medicine in the Emergency Department (C3MED), which was set up in 2003 and hosts an active email discussion forum.⁸
Similar efforts have been undertaken by the American College of Emergency Physicians (ACEP),⁹  the Society of Critical Care Medicine (SCCM),¹⁰  the American Association of Emergency Medicine¹¹  and the Society for Academic Emergency Medicine (SAEM).¹²
In Europe, one of the best-known initiatives to harmonize convergence of the ED and the ICU is ISICEM, the International Symposium on Intensive Care and Emergency Medicine. This non-profit organization, headquartered in Brussels, was set up in 1980. It currently runs a series of eight annual events, covering different aspects of intensive care and emergency medicine. Over the years, participation has grown from about 200 to over 6,000 from more than 100 countries.
 
Impact of ED on ICU: US and European studies
There have also been concerted efforts to assess the impact of emergency department volume and boarding times on ICU admission and patient outcomes. Two recent studies have catalysed considerable new attention in the topic.
The first is a retrospective cohort study on critically-ill ED patients for whom a consult for medical ICU admission had been requested over a 21-month period. It was published in ‘Critical Care Medicine’ last year by a US-based team from the Icahn School of Medicine at Mount Sinai, New York, and titled ‘Effect of Emergency Department and ICU Occupancy on Admission Decisions and Outcomes for Critically Ill Patients’.
The authors conclude that ICU admission decisions for critically ill ED patients were affected by ICU bed availability. However, higher ED volume and other ICU occupancy did not play a role. They also found that prolonged ED boarding times were associated with worse patient outcomes, suggesting a need for improved throughput and targeted care for patients awaiting ICU admission.
In August 2019, ‘Critical Care Medicine’ published findings online from another study on this topic, this one by a Dutch team from  six University Medical Centres at Amsterdam, Groningen, Leiden, Nijmegen, Rotterdam and Utrecht, along with the country’s National Intensive Care Evaluation (NICE) foundation.¹³  The retrospective observational cohort study conducted a registry analysis of 14,788 patients from the six hospitals, and found an association between emergency department to ICU time greater than 2.4 hours and increased hospital mortality after ICU admission

Ad-hoc and hybrid models
At present, there are two approaches to the challenge of intensive care in the ED. The more common is to have an emergency physician intensivist working standard ED shifts, and lending expertise on an ad-hoc basis to critically ill patients. A recent development is a ‘hybrid’ model. This earmarks a dedicated area of the emergency department for ramping up care to critically ill patients, with a dedicated physician providing intensive care only to such patients, typically for periods longer than an hour.
Supporters of the hybrid model state that it is easier and less expensive to establish with extra costs involving only the dedicated ED-ICU physician.

The ED-ICU
One of the most watched developments in recent years in care for critically ill patients in an ED is the development of ED-ICUs (emergency department intensive care units).
Two such facilities in the US, Stony Brook Resuscitation and Acute Critical Care Unit (RACC) in New York and Emergency Critical Care Center (EC3) in Michigan are considered as being both ED-ICU pioneers and best-of-class references for the concept.
EC3 is considered to be among the world’s most advanced emergency critical care centres. It was opened in February 2015 and has five resuscitation trauma bays and nine patient rooms, located adjacent to the main adult emergency department.
Due to this reputation, the case for ED-ICUs was strengthened after a recent study by EC3 found convincing improvements in survival as well as reduced inpatient ICU admissions.¹⁴  In effect, an ED-ICU can improve care and survival rates for the entire emergency department population.¹⁵
The EC3 study covered 350,000 ED patient encounters, and found that implementation of an ED-based ICU was associated with significant reductions in risk-adjusted 30-day mortality among patients, from 2.13 to 1.83 percent. The median time to ICU-level care for critically ill patients decreased from 5.3 hours to 3.4 hours, while the hospital ICU admission rate from the ED dropped from 3.2 percent to 2.8 percent.

References
1.https://www.sciencedaily.com/releases/2013/05/130514212946.htm2.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4351597/3.https://www.ncbi.nlm.nih.gov/pubmed/8319477/4.http://www.siz.be/education/training-in-critical-care/5.https://www.ncbi.nlm.nih.gov/pubmed/124545496.https://pdfs.semanticscholar.org/4f1b/5cea333174e599784e6a2d80c9b55b868b2e.pdf7.https://www.emra.org/fellowships/critical-care-fellowships/8.c3med@yahoogroups.com9.https://www.acep.org/criticalcaresection/10.http://www.sccm.org/Member-Center/Sections/Pages/Emergency-Medicine.aspx11.http://www.aaem.org/membership/critical-care-section12.https://community.saem.org/communities/community-home?CommunityKey=5dc206d8-d248-4f71-aecd-e0490cdc3ba913.https://insights.ovid.com/pubmed?pmid=3139332114.https://jamanetwork.com/journals/jamanetworkopen/fullarticle/273862515.https://medicalxpress.com/news/2019-07-department-based-intensive-patient-survival.html