By Kaitlyn Palmer, P.E., S.E., Contributing Writer

In the bustling environment of a healthcare facility with life-saving procedures, critical research and patient care always in motion, even the subtlest vibrations and noises can have profound effects. From the humming of machinery to the rumble of transit outside to a person walking down the corridor, these seemingly minor disturbances can disrupt delicate equipment, affect staff concentration and even impact patient comfort. 

Before creating or renovating healthcare spaces, facility managers, engineers and architects must understand the crucial importance of vibration and acoustics control within these specialized settings. Early in the process, they need to consider the sources of these disturbances and their potential impacts and develop effective strategies for mitigation. 

Finding and understanding vibration 

Vibration and noise in healthcare facilities can stem from various sources, each posing unique challenges. Mechanical, electrical, plumbing and technology (MEPT) equipment emit vibrations that can reverberate throughout the building. Transit, including cars, trains, buses, airplanes and helicopters, also contribute, as can pedestrian-induced vibrations, such as walking in hallways or adjacent rooms, with each step creating a forcing function on the floor system. It is essential for managers to understand which sources are prevalent in different areas of buildings and to focus on meeting specific limits required for each space. 

Healthcare facilities adhere to stringent vibration criteria to ensure the smooth operation of sensitive equipment and maintain a comfortable environment for patients and staff. These criteria vary depending on the area and type of facility. 

For instance, patient rooms have a vibrational velocity limit of 6,000 micro-inches per second (mips) according to the Facility Guideline Institute. Spaces for neurosurgery and microsurgery require a limit as low as 1,000 mips. Typical bench microscopes up to 400x magnification require a maximum vibrational velocity of 2,000 mips. MRI rooms can pose unique challenges, with vibration limits that can vary substantially with frequency. These may require a vibrational velocity as low as 200-500 mips. 

With the understanding of the major sources of vibration and noise, managers should carefully consider sensitive equipment locations when planning a new healthcare facility or renovating an existing facility. 

The most sensitive equipment is best located on the lowest levels where a thickened slab can diffuse vibration propagation and inertia blocks can be employed to reduce vibrations further. On elevated slabs, the most sensitive equipment should be thoughtfully located away from the middle of a bay and from major corridors carrying pedestrian traffic. Locating sensitive equipment in smaller bays also will improve vibration characteristics. 

Effective mitigation solutions 

Healthcare facilities employ various solutions tailored to their specific needs to mitigate vibrations and noise effectively. Floor strengthening techniques, like increasing stiffness or mass in certain areas, can be employed to meet vibration criteria. If floor strengthening is not possible or inefficient due to the sensitivity of the equipment, isolation techniques can be employed. Isolation techniques such as dropping a structural slab, using an isolated topping slab and designing massive inertia blocks can substantially reduce all vibration sources. 

Inertia blocks can be used for passive vibration mitigation due to their mass, or they can be designed to be supported on an active spring or pneumatic isolation system. After the placement of the inertia block mass, vibration testing can be performed, allowing the managers and engineers to determine if an active isolation system is necessary. 

Related: Proper Acoustics Help Improve Patient Recovery

If the performance does not meet the needs of the equipment, an active isolation system can be placed below the inertia block, and the block can be separated from the structural slab below. This adaptability in the field based on site-specific data is crucial for the most sensitive equipment. 

If extremely vibration-sensitive equipment is located on an elevated floor, an isolated intermediate level of structural framing supported directly on columns can be employed. Critical medical equipment may be hung from a series of rails supported on a mid-level structural system, limiting structure-borne vibrations from pedestrian traffic and MEPT systems. But the design of these structural systems depends on a specific set of equipment criteria, making them unable to provide ultimate flexibility and adaptability. 

Incorporating flexibility into the design of healthcare facilities is paramount for future adaptability. Understanding the criteria for each type of equipment and the generalized programming of space utilization allows for strategic planning and layout design. Structural engineers can provide vibration diagrams or heat maps describing the anticipated vibration performance of each region. 

These diagrams assist the team in allocating the current space and aide in evaluating the feasibility of future equipment installations. Considerations such as site location relative to transit, the placement of MEPT equipment and the siting of the most sensitive equipment in lower levels also can enhance flexibility and resilience. 

Planning for success

Effective vibration and noise control in healthcare facilities requires a proactive approach, employing a combination of efficient bay spacing and thoughtful programming and methods for isolation, floor strengthening and hung equipment solutions. Early discussions with the structural engineer about different construction types, efficient bay spacing, limiting corridor lengths adjacent to sensitive equipment and locating the most sensitive equipment on the lowest floors will aid in a successful project. 

Planning for future flexibility is essential, necessitating collaboration with structural engineers and equipment manufacturers to anticipate changes and adapt accordingly. By taking these proactive measures, healthcare facilities managers, engineers and architects can create environments prioritizing patient comfort, staff efficiency and the seamless operation of critical equipment. 

Kaitlyn Palmer, P.E., S.E., is a principal at LeMessurier specializing in structural engineering tailored to healthcare facilities.