Adapting Existing Hospitals for Surge Capacity

In the space of a just few short weeks, the novel coronavirus (COVID-19) has had a dramatic impact on health care systems around the world. As the pandemic spreads in the U.S., hospitals are taking fast action to prepare for anticipated surges should infections continue to grow at projected rates.

In the U.S. there are 941,520 licensed hospital beds, although only 810,764 can be used because of inadequate medical staff. More importantly, there are only 64,465 intensive care unit (ICU) beds spread across all 50 states, according to data compiled by ArcGIS. With the number of total infected people projected to exceed these numbers, the need for more hospital beds – and specifically, ICU beds – is critical.

Inpatient admissions rise daily, and many hospitals and state governments are taking steps to add ICU beds and isolation rooms or wings, create temporary facilities for treating COVID-19 and non-COVID-19 patients, and accelerate planned construction projects to get more beds online quickly.

In many cases, states are relaxing licensing and code requirements. While this can speed up the ability to create temporary expanded ICU spaces, thoughtful planning is required to address increased demands on the heating-ventilation-air conditioning (HVAC) systems that can help keep COVID-19-contaminated air out of a hospital’s air distribution systems. In addition, increased demands on the gas and power systems need to be assessed.

Health care engineers at WSP USA are helping their clients take quick action. The firm is deploying teams of mechanical and electrical engineers, medical gas experts, commissioning agents and testing and balancing professionals to provide assessments of existing systems and working with the clients’ team to formulate solutions that can be implemented immediately to meet the urgent needs of many health care facilities.

Facilities need to assess several key considerations before converting existing areas into ICUs and ensure they all maintain key attributes: additional power and medical gas capacity, positively pressurized patient rooms with higher air change rates, and support spaces to handle a more intense nurse-to-patient ratio.

“Given the current pandemic, not all of these attributes may be required for the needed surge capacity,” said Douglas Lacy, senior vice president in WSP’s Dallas office. “Additional medical gases and power for more ventilators are a must and accommodations for isolation of patients and ICU nursing to patient ratios are also key. However, positively pressurized patient rooms with higher air change rates may not be desirable; in fact, the ability to quickly adapt rooms to negative pressure, similar to airborne infection isolation (AII) rooms, may be more important.”

HVAC systems in medical buildings play a huge role in limiting the transmission of infectious disease to other patients and health care workers.

“The primary function of the mechanical engineer in the preparation for surge is to advise the hospital system on how to reconfigure and modify the existing HVAC system’s normal mode of operation,” said Gary Hamilton, senior vice president and health care practice lead in the Northeast region. “This supports the safe segregation of suspected and confirmed patients within controlled air environments, whether true isolation or modified alternative arrangements, as best suits their needs.”

The most critical mechanical ventilation systems are the air handling units and exhaust fans serving these controlled environments. Negative pressure is required to prevent the recirculation of the COVID-19 virus in the hospital through the hospital HVAC system.

“Analyzing the capabilities of the existing HVAC system is the most significant temporary action that will need to be assessed,” Hamilton said. “The idea is to remove air that is being contaminated by COVID-19 patients and bring outside air into the building to replace it.”

Some patients will be required to be placed in AII rooms for the purpose of performing respiratory procedures. These rooms will be in high demand and necessary to protect health care personnel from exposure to the COVID-19 virus because of high exposure from the cough-inducing procedures that are required.

“These rooms will run out extremely fast for hospitals with high surge,” Hamilton said. “The facilities team will work with mechanical engineers to determine the best approach to convert existing patient rooms into airborne infection isolation rooms.”

In these rooms, exhausted air from the modified airborne infection isolation rooms should be cycled through HEPA filtration before exhausting to outside.

The speed at which systems can be assessed, and changes implemented depends on mechanical ventilation system capabilities and how it was designed to be operated.

“Some mechanical ventilation systems can be easily altered if they were designed with the flexibility handle such temporary operational needs,” he said. “This will require a testing and balancing team along with a mechanical engineer to ensure that the system will meet its new operational demands.”

Hamilton added that the conversion of airborne infection isolation rooms will be more intricate and require an assessment of the room type to determine if they can function as negative isolation rooms.

Extra demands will be placed on medical gas systems at facilities as a result of the expected surge.

“The surge will result in heavy ventilator use within the existing ICU rooms and modified ICU spaces,” said Larry Wilson, vice president with WSP in Chicago.

With ventilators requiring up to five times the typical medical air and oxygen versus a standard ICU room, modifications to these systems are especially critical.

“Without design calculations available that match the installed piping layout, it will be difficult to predict system behavior if each ICU room has a ventilator in operation, especially if they’re each operating with 100 percent oxygen use,” Wilson said. “Also, in a fully occupied ICU suite over an extended period, the rate of consumption of oxygen product will increase substantially.”

In many cases, the existing oxygen and MS-AIR systems servicing these rooms will be inadequate to support the use of ventilators regardless of which mode of clinical operation is used. “These rooms would be useful, however, for patients who need oxygen but don’t need a ventilator to breathe for them,” he said.

Wilson added that pre-operation and recovery rooms with ventilators could also support patients who need oxygen, but do not need a ventilator.

However, it is important to note that the medical oxygen and MS-AIR system pipework are often designed with enough diversity to handle increased flow. The increase demand caused by multiple ventilators can be helped by working with the oxygen supplier to raise the operational pressure of the system. It is important that the medical gas designer is brought onboard to fully analyze the system capabilities.

Another strategy is to provide temporary supplemental oxygen and MS-AIR sources in strategic locations.

“These new sources would be stored as a high-pressure gas in cylinders connected to a manifold, which could be tied into existing piping so that there would be almost no pressure drop in the piping because of the proximity of the source to the outlets, thereby preserving flow and pressure,” Wilson said.

Facility managers should be in constant communication with their gas supplier in order to ensure that product can be delivered in a timely manner and that access to bulk plants and loading docks has not been compromised by any temporary structures or other obstacles.

Furthermore, some gas suppliers will not allow their employees to enter the hospital so the facility will need to make its own staff available to handle incoming full or outgoing empty cylinders or containers, including making and breaking connections at manifolds in interior rooms.

The increased daily census and increased use of ventilators for more patients can impose a marginal increased load on the electrical infrastructure.

“If the surge capacity is accomplished in existing patient bedrooms, procedure rooms, exam rooms and similar spaces this increase will only be noticeable from a consumption standpoint but should not present major concerns in normal operating conditions,” Lacy said.

Lacy advised that hospital facilities should be assessing any risk of a power outage during these high census events now, to make sure the facility’s essential electrical system can support the added load if there were to be a second impact event, such as a storm or earthquake, that would take normal utility power down and put the facility on their standby generator system.

Not unlike other disaster preparedness planning, accurate assessments of peak electrical loads and projected census surges that follow natural disasters are necessary. Testing should be done during times of peak usage to prevent false representations of real load conditions that the system would experience to support in an actual power outage event.

“The ideal is for permanently installed power monitoring systems to be used to assess if the essential standby generators can support the facility during a surge,” Lacy said. “In the absence of these metering systems, a facility should consider conducting incremental tests during normal operating hours to help to project total load needs for the generator backup system.”

If other areas in the health care facility – multi-purpose rooms, medical offices or clinic spaces that are not traditionally used to house long-term patients – are being used for surge census, but may have limitations in their electrical distribution systems. Extending emergency power to areas currently without that capability may require introduction of portable emergency generators into the normal power system to supplement existing essential source equipment.

The modifications needed throughout the duration of the surge condition will trigger some operational issues, since the modified areas will require ongoing monitoring to ensure that the rooms, floors or zones are meeting the negative pressure requirement and are safe places for patient treatment and heath care worker safety.

WSP recommends installing temporary pressure monitors with connectivity to allow remote monitoring and inbuilt alarms to indicate when conditions vary. WSP is assisting clients in the troubleshooting of the modified systems to ensure that everything meets the required operational intent.

“Together, HVAC, medical gas systems, and power play a huge role in keeping hospitals functioning properly and providing quality care to patients, as well as limiting the spread of infectious disease to other patients and health care workers,” said Hamilton. “When we protect our health care workers, we protect the public.”

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