“The concept for ER One actually began two years before the 9/11 attacks in New York City,” says Michael Pietrzak, MD, vice president of medical affairs for HKS Architects in Dallas, who has served as a project principal since its inception. “The 9/11 tragedy unfortunately confirmed that emergency departments within hospitals need to be better prepared to handle and respond to large-scale emergencies without compromising the safety and effectiveness of the entire hospital.”

The ER One prototype is to be built at Washington Hospital Center (WHC), located less than two miles from the U.S. Capitol building. With an estimated construction cost of nearly $125 million, ER One at WHC will have unparalleled capabilities to manage incidents that produce mass casualties. It will also serve as a model and demonstration facility for other emergency centers in metropolitan areas vulnerable to such incidents.

“ER One is not designed to be a true biocontainment unit,” says Pietrzak. “Instead we call it an ‘immune’ facility since it has design features that serve as an inherent immune system including self-decontaminating surfaces, advanced air-handling systems, assured water supply with internal purification capabilities, and built-in radiation protection.”

Pietrzak adds that the facility will have extensive isolation capabilities and the necessary flexibility to handle dramatic surges in patient capacity and throughput while still maintaining a healthy environment.

ER One will be capable of handling large numbers of patients, as many as 200 patients per hour or 2500 patients per day, which is several times the normal rate for this hospital. During incidents involving chemical exposures, ER One is designed to accommodate the decontamination of 400 victims per hour.  This prototype facility also includes a wireless information system capable of tracking thousands of patients simultaneously.

Multiple Portals

In order to increase security and handle a higher patient throughput, ER One at WHC will have multiple entrances called “portals.” Because each entrance is distinct and capable of multiple functions, any portal can be closed off to isolation sections or the entire emergency department. Managers within the emergency department will be able to determine which and how many portals are open at any given time. The portal functions include identification of threats or unauthorized materials, detention and disposition systems, and decontamination capabilities.

“The portal concept was borrowed from airports allowing flow, control, and security for large numbers of individuals,” says Pietrzak. “Further, ER One borrowed the concept of compartmentalization from submarines that have the ability to isolate certain sections without compromising the entire ship.”

He explains that in addition to the distinct portal entrances the emergency department itself will be designed to contain compartmentalized sections so that specific areas can be safely isolated by using specialized air pressure and independent filtration systems.

“This will give us the capability to contain disease threats or unauthorized materials within a specific compartment or pod within the emergency department, yet allow remaining areas within the department and the rest of the hospital to continue operating as normal,” says Pietrzak.

Pietrzak also points to the scalable capacity of ER One. By adding approximately 15 percent more sf to a regular ER pod the facility has the capacity to scale up to a four- to five-fold capacity for additional patient beds and decontamination showers, when necessary.

The exterior of the the facility will also be designed to enhance the hospital security, including a sacrificial façade, a protective canopy, and anti-progressive collapse features.

Air-Handling Systems

Operational control and design of the engineering systems in the emergency department are necessary to support patient grouping strategies in order to prevent the spread of disease. The HVAC systems are specifically designed to support this function.

As a result, ER One will have its own independent air-handling system to distinguish it from the rest of the hospital. It will use single-room and single-zone modular compartmentalized ventilation systems, each with negative pressure capability using 100 percent filtered and non-re-circulated air.

“Our design will physically separate the intakes and the exhaust to protect the entire air-handling system,” says David Duthu, founding principal of ccrd partners in Houston, who are serving as the lead mechanical engineer for the ER One. “The intake for the air-handling systems will be sequestered in order to protect it from being damaged by intentional vandalism such as aerosol sprays, or accidental incidents such as outside explosions.”

He adds that since the ventilation systems are considered part of the critical axis of the hospital, they needed to be rigorously protected.

Isolation Rooms

“Without having a full-scale biocontainment unit, the isolation rooms within ER One will operate according to level 2 or level 3 biological safety level standards,” says Duthu. “This means that we have to be able to control the airflow within the isolation rooms from positive to negative in order to maintain containment, i.e., keep the bad contained with negative pressure and keep the unwanted out with positive pressure.”

Duthu explains that this will be accomplished by using a differential pressure control system in conjunction with a directional airflow offset system.

“The ability to go from positive to negative airflow is extremely unique in healthcare environments since it is typically not recommended by JHACO standards,” says Duthu. “This particular facility will have an active control system and the necessary pressurization capability to actually direct the airflow as the need takes place.”

“The use of a combination directional and pressure control allows us to monitor airflow and communicate back to an active control system to provide incremental offset reset adjustments of the air systems to ensure that we are maintaining the proper amount of airflow at any given time,” says Duthu.

ER One will also have the ability to purge the overall environment if necessary by going to 100 percent outside air with 100 percent exhaust in the overall systems.

“We have designed the number of outside air handlers needed for effective pre-treatment of the outside air systems,” says Duthu. “On the secondary distribution side we have the ability to take advantage of the localized air handlers and can increase the ventilation rate by 20 to 30 percent to accommodate the need for a scale up condition while maintaining accurate temperature and humidity control.”

He adds that the outside air pre-treatment equipment is maintained with an n+1 redundancy scale and the exhaust systems are sized and sequenced appropriately in order to move large amounts of air depending on the scale of the event.

“Similar to the supply air system design, the exhaust system design uses a manifold exhaust system configuration with staged component fans so that all of the air exhausted is collected to a centralized plenum. The exhaust fans are staged so that fans can be brought on as needed,” says Duthu. “The use of multiple redundant fans that can operate in a staged fashion at 50 percent or less of their normal capacity, except during an incident when they can be turned up to 100 percent, allows the Washington Center Hospital to reduce energy cost during normal operating periods.”

The control systems use a high-speed monitoring routine that interfaces with chemical detection devices. When these devices are online, they are able to make an assessment and provide feedback through the computer to make adjustments in the air conditioning control system as needed.

The filtration systems within ER One will have the ability to operate in two modes. In normal mode it will use by-pass filtration but during an incident the filtration system will have the capability to operate in high-grade filtration for detection of chemical or radiological contamination.

“Utilizing empirical data, one of the things we’ve learned is that using three 9s or 99.95 HEPA filters is sufficient for even the most stringent filtration needs,” says Duthu. “There’s no reason to go five 9s.”

Plumbing Systems

ER One will use advanced plumbing fixtures such as low aspirating nozzles on sinks and showers, which reduce splashing and aerosolize the liquid. The ability to select, isolate, and decontaminate areas will be accomplished with gaseous decontamination techniques, as well as with traditional wipe-down methods. Piping to facilitate gaseous decontamination will be provided between the treatment areas and the interstitial spaces.

Water purification and liquid effluent treatment, either with chemical or heat treatment, will be provided in the event that external sources are compromised and not accessible. Water sources in the treatment areas will have back flow prevention at the interstitial barrier. Plumbing vents, although not required to be filtered, are being evaluated for filtering prior to discharge to the environment.

Interstitial Space

ER One includes interstitial spaces, above and below the emergency department. The interstitial space reinforces ER One’s system reconfiguration and flexibility, and enhances the facility’s overall security and environmental protection by allowing maintenance on the mechanical and electrical systems to take place without causing disruptions or entry into the medical treatment area.

“If there is an incident that creates a contaminated portal, the interstitial space will give us the ability to still access all of the HVAC equipment and the filtration system which includes HEPA filtrations in the space directly above the ER,” says Duthu.

He adds that the interstitial space is also used to house spare parts inventory deemed critical to system dependability in the event of HVAC equipment component failure. This on-site repair response allows ER One to be restored to full operating  system capacity in a minimum time frame in the event the facility must  scale up to handle dramatic patient surges.

“The interstitial space is key to ER One being able to house and maintain a large number of pieces of equipment without disruption to the healing environment,” says Duthu. “Categorizing operations and maintenance service of the environmental systems will be critical to the commissioning of the facility, as well as to long-term operations and facility maintenance.”

Unique to ER One is the ability to isolate a treatment room for gaseous decontamination, notes Duthu. In order to facilitate system or room isolation for a decontamination procedure, the floors of the interstitial space directly above ER One will include bioseal dampers at all penetrations.  Further, the interstitial floor itself will have an epoxy coating and utilize curbs at all penetrations through the floor.

“An added benefit to the curbed floor penetrations on the interstitial floor is if we ever have to decontaminate the interstitial space itself by going into a full wash-down mode, the curbs will prevent seepage or leakage to the space below, so that no water will drip down into the ER space,” says Duthu. “Floors with epoxy coatings are being used effectively in BSL-3 and BSL-4 laboratories, particularly in enhanced labs features and animal facilities.”

Serving by Example

“Based on the costs and the high-end technology going into ER One this project will most likely be a one-of-a-kind facility,” says Pietrzak. “However we hope that ER One will also serve as good example of how hospitals can enhance safety and isolation features without having to build full-scale biocontainment units.”

He adds that he hopes hospitals will look at the overall ER One concept and use it as a menu of innovative ideas that even if used separately will increase the effectiveness of their emergency department.

By Amy Cammell

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