Healthcare / Service redesign
Adapting existing hospitals for surge capacity
By Andrew Sansom | 16 Apr 2020 | 0
Healthcare engineers are providing rapid assessments of existing systems and solutions that can be implemented quickly to meet the needs of hospitals and communities. This article, authored by Gary Hamilton, Larry Wilson and Douglas Lacy at WSP USA, explores some of the key considerations involved in this process.
In the space of a just few short weeks, the novel coronavirus (COVID-19) has had a dramatic impact on healthcare systems around the world. As the pandemic spreads in the United States, hospitals are taking fast action to prepare for anticipated surges should infections continue to grow at projected rates.
In the US, 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 across all 50 states, according to data compiled by ArcGIS (correct as of 8 April). 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 and 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.
Healthcare engineers at WSP USA are helping medical providers take quick action. We’re deploying teams of mechanical and electrical engineers, medical gas experts, commissioning agents, and testing and balancing professionals to deliver assessments of existing systems, and working with medical provider teams to formulate solutions that can be implemented immediately to meet the urgent needs of many healthcare facilities.
Assessing the situation
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 pressurised 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,” says 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 pressurised 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.”
Medical ventilation systems
HVAC systems in medical buildings play a huge role in limiting the transmission of infectious disease to other patients and healthcare 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,” says Gary Hamilton, senior vice-president and healthcare practice lead in the Northeast US 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 its HVAC system.
“Analysing the capabilities of the existing HVAC system is the most significant temporary action that will need to be assessed,” says Hamilton. “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 healthcare personnel from exposure to the COVID-19 virus, owing to high exposure from the cough-inducing procedures that are required.
“These rooms will run out extremely fast for hospitals with high surge,” Hamilton says. “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 AII rooms should be cycled through high-efficiency particulate air(HEPA) filtration before exhausting to outside.
The speed at which systems can be assessed and changes implemented depends on the capabilities of the mechanical ventilation system, and how it was designed to be operated.
“Some mechanical ventilation systems can be easily altered if they were designed with the flexibility to handle such temporary operational needs,” he says. “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 adds that the conversion of AII 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,” says Larry Wilson, vice-president with WSP in Chicago.
With ventilators requiring up to five times the typical medical air and oxygen compared with 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 behaviour if each ICU room has a ventilator in operation, especially if they’re each operating with 100-per-cent oxygen use,” Wilson says. “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 says.
Wilson adds that pre-operation and recovery rooms with ventilators could also support patients who need oxygen but do not need a ventilator.
It’s important to note, however, that the medical oxygen and MS-AIR system pipework are often designed with enough diversity to handle increased flow. The increased demand caused by multiple ventilators can be helped by working with the oxygen supplier to raise the operational pressure of the system. It’s important that the medical gas designer is brought onboard to fully analyse 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 explains.
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, because some gas suppliers will not allow their employees to enter the hospital, 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.
Ensuring power availability
The increased daily census and increased use of ventilators for more patients can impose a marginal greater 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 and should not present major concerns in normal operating conditions,” Douglas Lacy says.
He advises 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, which 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 conducted 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 says. “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 back-up system.”
If other areas in the healthcare facility – multi-purpose rooms, medical offices or clinic spaces that are not traditionally used to house long-term patients – are used for surge census, it’s important to recognise that they 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 healthcare worker safety.
We recommend installing temporary pressure monitors with connectivity to allow remote monitoring and inbuilt alarms to indicate when conditions vary. We’re also 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 for patients, as well as limiting the spread of infectious disease to other patients and healthcare workers,” says Hamilton. “When we protect our healthcare workers, we protect the public.”
This article was originally published on WSP’s website at https://www.wsp.com/en-US/insights/2020-covid-19-adapting-existing-hospitals-for-surge-capacity