Sterilisable 'shield' helps protect healthcare workers

Researchers from the National University of Singapore (NUS) have invented a foldable tent-like device that serves as a physical shield to reduce the risk of exposure to pathogens for healthcare workers performing droplet- and aerosol-generating procedures on COVID-19 patients.

Known as the Droplet and Aerosol Reducing Tent (DART), the device was designed in collaboration with doctors from the National University Hospital (NUH). The multidisciplinary team took less than two months to develop DART and validate its performance.

Extra protection for frontline healthcare workers

The COVID-19 pandemic has dramatically increased the need for infection control when intubating patients. Intubation is the placement of a flexible plastic tube into the windpipe to maintain an open airway or to serve as a conduit through which to administer certain drugs. The removal of this plastic tube is known as extubation. These are risky procedures that may put healthcare workers in danger of becoming infected.

Evidence from the SARS outbreak in 2003 showed that healthcare workers involved in intubation were more likely to contract the disease compared with those who did not. This risk has similar implications for the current coronavirus outbreak, affecting anaesthesiologists, operating theatre staff, intensive care unit staff and even first responders who are required to intubate collapsed patients in the COVID-19 general ward.

“Healthcare workers caring for patients run the risk of being exposed to known, suspected or even asymptomatic COVID-19 patients,” said Dr Deborah Khoo, a Consultant at the NUH Department of Anaesthesia. “The DART serves as an additional physical barrier to infection and provides enhanced protection for healthcare staff at a time when they need it the most, giving us greater peace of mind and enabling care to continue safely for both patients and healthcare workers in the hospitals.”

Practical and versatile solution

DART is a portable, tent-like structure that can be placed around the patient’s head when intubating or extubating. It weighs 3 kg and can be folded into a flat structure measuring around 51 x 55 cm, with a thickness of 3 cm, making it easy to transport, store and sterilise. It is also simple and fast to set up.

The device features transparent polycarbonate panels, 3D printed nylon joints and Delrin inserts. These durable materials were chosen to enable the device to be sterilised by all standard forms of decontamination used in hospitals, such as elevated temperature autoclaving and using alcohol of 70% concentration. This facilitates the re-usability of the device and eliminates the risk of cross-contamination.

Arm access ports are situated on the back and side panels of the device, while the snap-on flanges allow the attachment of disposable sleeves or diaphragms. This addresses the concern of the arm ports being high-risk areas of contamination, and gives the healthcare workers the option to use either sleeved or diaphragm seals — materials easily available in hospitals — according to their preference. The elliptical shape of the access ports gives the user more leeway for arm movements and to manoeuvre, which is important when handling the patient.

A key feature of the DART is its ability to direct air within itself through a high-efficiency particulate air (HEPA) filter. It has a set of connectors that enables suction from a central vacuum system, or by a battery-operated fan attached to a HEPA filter. The negative pressure generated reduces leakage of exhaled aerosols or droplets from the patient out of the confines of the DART.

Preliminary findings by the research team showed that the DART performs its barrier function as designed, and the exhaust function via the HEPA filter gives additional assurance to the user.

Prototype testing in Singapore hospitals

The research team has produced 25 prototypes which are being tested in different departments and hospitals around Singapore. The team is looking to swiftly refine the DART based on the feedback provided by different medical departments, and hopes to provide the device as a form of medical aid to Singapore hospitals as well as hospitals in the region. The team will be partnering with Temasek Foundation to distribute the DART, complementing its donation of ventilators to the region.

Image caption: The multidisciplinary team took less than two months to develop the Droplet and Aerosol Reducing Tent (DART).

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