Abstract
The Coronavirus disease 2019 (COVID-19) pandemic has profoundly impacted healthcare systems globally, highlighting the critical need for effective infection control measures, particularly in healthcare settings and densely populated public spaces. This thesis explores three crucial areas that can manage or mitigate the transmission of respiratory infectious diseases: aerosol generation during surgeries with the usage of airway management devices, the development of Vented Individual Patient Enclosures (VIPER) for infection control, and the development of a negative-pressure ventilation system for toilets to reduce fecal-oral transmission.The first investigation focuses on understanding the risks associated with aerosol generation during anesthesia, specifically when using supraglottic airway devices (SADs). The COVID-19 pandemic reshaped how healthcare was delivered, and many hospitals abandoned the use of SADs because of a perceived risk of aerosol generation during the anesthesia for patient surgery. Concerns exist about aerosol exposure from an incomplete airway seal with SADs, intermittent positive pressure ventilation (IPPV), and expiration around a deflated tracheal tube cuff, which can release unfiltered exhaled gases. The actual aerosol risk of SAD during IPPV remains unclear. To address this, a clinical study was conducted in two hospitals in Hong Kong involving 21 low-risk adult patients undergoing elective surgery. Aerosol concentrations generated were measured during the usage of second-generation SADs, including iGel® and LMA® Supreme™ brands, using an optical particle sizer (OPS) in the operating theatre. The study revealed that while SADs generate little aerosols, the levels are significantly lower than those generated during some respiratory activities, such as talking or coughing in an awake patient. This study has vital implications for all healthcare workers involved in airway management using SADs during surgery to balance the risk of COVID-19 transmission and further prevent respiratory infections.
The second primary focus of the thesis is the development of the Vented Individual Patient Enclosures (VIPER) for Respiratory infectious disease control, which was designed as a rapid-response solution to protect both patients and healthcare workers from the spread of airborne pathogens in overwhelmed healthcare settings. The VIP system is a portable, negative-pressure enclosure that creates a controlled environment around patients, effectively containing and removing harmful aerosols. This system is particularly relevant when hospital infrastructure is stretched thin, such as during a pandemic when the availability of Airborne Infection Isolation Rooms (AIIRs) may be limited. Both numerical simulations and experiment validations demonstrated that the VIPER system significantly reduces aerosol transmission, removing up to 97.92% and 99.96% of aerosols on a micron scale within 5 minutes of the VIPER system operation. Moreover, the VIP enclosures comply with and exceed the Centers for Disease Control and Prevention (CDC) recommendations for AIIRs to maintain negative pressure and achieve high air change rates. The VIP system is flexible, scalable, and cost-effective, making it an innovative and practical solution for various healthcare settings. It offers significant advancements in protecting healthcare workers and patients from airborne infectious diseases.
The third primary focus of the thesis is developing a negative pressure ventilation system for toilets to address the aerosol transmission risks associated with toilet flushing, particularly in public toilets, where fecal-oral transmission of viruses, including SARS-CoV-2, can occur. Flushing toilets can generate aerosols that contain viral particles, which can linger in the air and contribute to spreading infectious diseases. The thesis introduces a novel negative-pressure ventilation system integrated with toilet lids to combat this. This system reduces aerosol dispersion during flushing, mitigating airborne transmission risks. Through experimental studies, the effectiveness of this system was validated, showing that it can remove over 99.7% of aerosol particles generated during flushing within just 20 seconds. The system’s automatic control features further enhance its usability in shared restroom facilities, offering a practical and immediately deployable solution to reduce public health risks associated with aerosolized pathogens in public toilets.
In conclusion, this thesis provides comprehensive insights and innovative solutions to address the complex challenges of managing aerosol transmission in healthcare and public settings. Engineering investigations and measurements offer suggestions for clinical approaches to healthcare delivery during the infectious disease pandemic. Developing strategies such as the VIPER enclosures and the negative-pressure ventilation system for toilets highlights the importance of engineering interventions in infection control. These solutions address the immediate concerns raised by the COVID-19 pandemic and offer long-term benefits for public health infrastructure and the prevention of future respiratory infectious disease outbreaks. The research and technologies proposed in this thesis present scalable, cost-effective approaches that can be rapidly deployed to protect populations and enhance infection control practices in various environments, providing preparedness for future pandemics and other public health emergencies.
| Date of Award | 11 Sept 2024 |
|---|---|
| Original language | English |
| Awarding Institution |
|
| Supervisor | Steven WANG (Supervisor) |