Over the past few years, there has been an increased emphasis on negative pressure isolation rooms. These rooms ensure patients within them can be cared for without the risk of spreading highly infectious viruses (i.e., those that spread through the air). Isolation rooms and their counterparts, positive pressure rooms (protective environments), help medical centers provide quality care while also reducing infection risks for immunocompromised staff and patients. Creating these spaces often requires the specification of specialized air exchange monitoring systems as well as creating environments that facilitate the ability of these systems to work as intended.
The complexity of harmonizing several architectural systems for positive and negative pressure rooms can be daunting when examined as a whole. That said, healthcare facility managers can help improve a medical center’s hygiene and ability to isolate patients who need extra precaution by looking to the doors they use.
Interior sliding doors can reduce air turbulence when operated correctly, which helps air exchange systems maintain sterile fields as well as limits the amount of cross-contamination between spaces. Both qualities can help improve patient outcomes and enhance the quality of care a medical center can provide.
Isolation Rooms & Protective Environments Use Multiple Systems To Maintain Sterility
Isolation rooms and protective environments safeguard patients and those in adjacent hallways or corridors through the use of pressurized air – creating either negative pressure or positive.
Negative pressure rooms have a lower air pressure than what is around them in order to minimize contagion risks to others when an admitted patient has an infectious disease. They use filtered exhaust systems to pump air from non-infected areas through the infected area and away from the healthcare facility. This reduces the potential for dangerous particles to be released into adjacent spaces even when a door is opened. Positive pressure rooms work in the opposite manner. They constantly pump clean and filtered air into a room to minimize potential infection risks for immunocompromised patients, whether or not they themselves are sick.
Both types of rooms, in general, require a minimum of 12 air changes per hour and often rely on sophisticated air change and filtration equipment as well as monitoring systems. Further, both rooms require door systems with gasketing that passes pressure testing standards such as UL 1784. Finally, the floors, ceilings, walls and windows must be thoroughly sealed to ensure no contaminates leave or enter the space.
The Part Doors Play in Infection Control
When it comes to both types of pressurized rooms, doors play a vital role in maintaining the space’s functionality while also allowing access by medical personnel. For these spaces, doors that open directly into the room should be self-closing, and the closing mechanisms should operate at a speed that reduces air turbulence. When closed, a door should be able to provide a seal that stops unwanted air from leaving or entering the room.
In addition, it is important that the operation of doors that lead directly into pressurized spaces do not compromise the level of sterility of the room or adjacent corridors. Swing doors can cause large eddies of air turbulence that compromise the effectiveness of both positive and negative pressure rooms.
A 2016 research study examined how swing doors and air exchange systems work together. The authors found that air exchange rates had only “a small effect” on air volume exchange across the doorway, meaning the opening and closing of a swing door can significantly reduce the overall effectiveness of air exchange systems within isolation rooms and protective environments.
The Benefits of Sliding Doors for Negative & Positive Pressure Rooms
Since swing door operation can affect the levels of protection afforded by pressurized environments, the International Health Facility Guidelines (IHFG) recommend the use of sliding doors for these areas “and any other spaces which have been identified as an infection control risk.” This is due to a sliding door’s method of operation.
By sliding along a wall, these doors substantially reduce air turbulence and cross-contamination between adjacent rooms. Using smoke visualization tests and water tank simulations, several studies found that single-leaf sliding doors offer significantly lower air turbulences when operated within designated parameters and also represent the least amount of air exchange between rooms when compared to single- and double-leaf swing doors.
Because air exchange systems have limitations to their ability to offset air disturbances caused by door opening, door specification receives added emphasis in pressurized environments. Sliding doors can help reduce the risk of airborne diseases contaminating either the room itself or adjacent spaces, improving the quality of care a medical center can provide and protecting those at higher risks of infection.
Automation Further Increases Building Hygiene
It is important to note that the above studies explain the speed with which a door is opened also has an effect on air volume exchange. This means that even if a sliding door is specified, medical professionals will need to operate it below certain thresholds to ensure it performs as intended.
In light of this information, designers can look to automatic sliding doors to sideline this risk. Because they can be programmed to open and close at set speeds, automatic sliding doors can consistently reduce air turbulence within positive and negative pressure rooms.
In addition, automatic sliding doors can provide hands-free operation to limit touch points within the built environment. This translates to fewer chances of contact with contaminated surfaces, which can contribute to a more hygienic environment overall. This is particularly important in protective environments as patients within these rooms need to be shielded from outside contagions.
Opening the Door to Better Healthcare
When specified with appropriate seals and gasketing, both automatic and manually operated sliding doors provide a range of benefits to isolation rooms and protective environments. As such, they are recommended for these spaces by IHFG where allowable by other codes. They can also be used in other areas throughout healthcare environments to contribute to a more navigable, accessible and efficient interior. While sliding doors provide several benefits to these applications, specifiers should always verify the level of air infiltration required for specific openings and how that intersects with the HVAC system design to determine the appropriateness of any product solution.
Tysen Gannon, LEED AP, AD Systems has more than 15 years of experience in the architectural products industry, including roles in sales, product management, research and marketing, with a focus on glass and glazing, fenestration and façade systems. Website: www.specadsystems.com.
 Kalliomäki, P., Saarinen, P., Tang, J. W., & Koskela, H. (2016). Airflow patterns through single hinged and sliding doors in hospital isolation rooms – Effect of ventilation, flow differential and passage. Building and environment, 107, 154–168. https://doi.org/10.1016/j.buildenv.2016.07.009
 Tang, J. W., Nicolle, A., Pantelic, J., Klettner, C. A., Su, R., Kalliomaki, P., Saarinen, P., Koskela, H., Reijula, K., Mustakallio, P., Cheong, D. K., Sekhar, C., & Tham, K. W. (2013). Different types of door-opening motions as contributing factors to containment failures in hospital isolation rooms. PloS one, 8(6), e66663. https://doi.org/10.1371/journal.pone.0066663
Saarinen, P. E., Kalliomäki, P., Tang, J. W., & Koskela, H. (2015). Large Eddy Simulation of Air Escape through a Hospital Isolation Room Single Hinged Doorway–Validation by Using Tracer Gases and Simulated Smoke Videos. PloS one, 10(7), e0130667. https://doi.org/10.1371/journal.pone.0130667
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