Negative Pressure Isolation Ward Research Articles

Airflow and aerosol transport in the hospital isolation zone based on dynamic scenarios

To contain the leakage of viral aerosols, buffer rooms are usually provided in front of isolation wards. However, dynamic events of door movement and healthcare worker (HCW) walking will result in highly concentrated aerosols intruding into the buffer room from the ward, challenging the control of virus transmission risk. In this work, airflow exchange and bioaerosol particle transport between the negative-pressure isolation ward and the buffer room under dynamic scenarios were studied by transient computational fluid mechanics (CFD) simulation, thereby the fate of particles was divided into invasion stage and decay stage. The effects of ventilation pattern and HCW location on the concentration level and attenuation trend of particles were quantitatively analyzed. The results showed that increasing the HCW walking distance could increase the peak particle concentration within the buffer room by 4.5 % during the invasion stage. The effect of the buffer room ventilation layout on air exchange and particle transport was more pronounced than the HCW stay position. In the decay stage, the two more effective ventilation layouts could decrease the complete clearance time of particles and the particle concentration in the breathing zone by 31 % and 42 %, respectively. To reduce the infection risk, bioaerosol levels need to be reduced both in the buffer room and in the HCW breathing zone.

Numerical study of airflow pattern and bioaerosol dispersion during door motion in a negative pressure isolation ward

Negative pressure isolation wards are typically equipped with buffer rooms to prevent the spread of infectious bioaerosols into clean areas and facilitate timely removal. The opening and closing process of sliding doors is very common in wards. Since the air exchange characteristics of the doorway affect the risk of infection and the efficiency of particle removal within the buffer room, the boundary transformation method and dynamic numerical simulations are used to study the airflow patterns and particle diffusion during door motion. The corresponding cases for different pressure differences, temperature differences, and door motion modes are compared. The results indicate that under different temperature differences, the particles can be dispersed uniformly in a short time (about 23s), and there is no phenomenon of particle aggregation. Compared to the initial pressure difference, adjusting the initial temperature difference has a more pronounced effect on air infiltration and particle concentration trends. The peak particle concentrations within the buffer zone under negative temperature differences are on average 19.9 % higher compared to the positive temperature differences. However, particle concentrations at negative initial temperature differences decay more rapidly. It is found that by reducing the duration of full door opening from 6s to 2s, the time for particles to be completely removed can be reduced by 30.6 %. This study provides useful information for evaluating the risk of infection and developing operational modes of the buffer room.

Spatial and temporal distribution of bioaerosols produced by patients with different postures in a negative pressure isolation ward under different ventilation modes

The high concentration of viral bioaerosols within the negative pressure isolation wards could pose a challenge to preventing potential cross-infection amongst healthcare workers (HCWs) and patients. Using the Euler–Lagrange methodology, this study numerically simulated the spatial and temporal distribution characteristics of bioaerosols in a typical negative pressure isolation ward as well as determined the interaction of ventilation mode and patient posture on ward ventilation performance. The removal effect of particle groups produced by two respiratory behaviours (breathing and coughing) was quantitatively analyzed, and the effect of exhaust air ratio and air exchange rate on particle distribution was discussed. The results showed that the migration characteristics of bioaerosol particles were sensitive to both the ventilation pattern and patient posture, which showed significant interactions. On this basis, the ventilation pattern with the best ventilation performance was evaluated, showing a particle removal effect of 70–85%. Due to the initial momentum difference, the diffusion behaviour of cough and breath particles was not consistent, but optimizing the airflow distribution near the exhaust outlet could improve their removal efficiency in the meantime. Further studies found that equal exhaust air velocity ratio facilitated the removal of aerosol particles, and an appropriate increase in the air exchange rate could also reduce the particle content.

Influence of talking behavior of infected patients and the associated exposure risk in a ventilated negative-pressure ward

Negative-pressure isolation ward is a primary choice in preventing the spread of outbreaks and safeguarding patient recovery. Inside the ward, patients with respiratory diseases generate virus-carrying bioaerosols through breathing and talking, posing a very high risk of infection to healthcare workers. In this paper, we used numerical simulation to compare the effects of different respiratory behaviors, such as normal breathing, prolonged talking, short talking, and alternating talking, on the spatial and temporal distribution of aerosols in a ward, and to study the risk of infection for healthcare workers. It was found that a short period of time in which a patient talked in a ward increased aerosol concentrations by four orders of magnitude compared to normal breathing. In the ward with the ventilation of up-supply, or the one with side-supply, the impacts of aerosol generation from talking accounted for 62.4% and 42.6% of the total time, respectively. The overall infection risk in wards designed with side-supply ventilation was lower. Patient talking time changes did not affect high-risk areas. However, when healthcare worker and patient talked alternately, the aerosol impact time was slightly extended. In addition, the aerosols produced by talking were mainly deposited on the beds and floors, leading to higher exposure risk for healthcare workers during direct contact with beds. It is hoped that the results of this study can be used as the data basis for the study of aerosol pollution control strategies in medical scenarios, and provide useful suggestions for reducing the risk of infection.

Study on the migration characteristics of bioaerosols and optimization of ventilation patterns in a negative pressure isolation ward considering different patient postures.

Due to the serious global harm caused by the outbreak of various viral infectious diseases, how to improve indoor air quality and contain the spread of infectious bioaerosols has become a popular research subject. Negative pressure isolation ward is a key place to prevent the spread of aerosol particles. However, there is still limited knowledge available regarding airflow patterns and bioaerosol diffusion behavior in the ward, which is not conducive to reducing the risk of cross-infection between health care workers (HCWs) and patients. In addition, ventilation layout and patient posture have important effects on aerosol distribution. In this study, the spatial and temporal characteristics as well as dispersion patterns of bioaerosols under different ventilation patterns in the ward were investigated using the computational fluid dynamics (CFD) technique. It is concluded that changes in the location of droplet release source due to different body positions of the patient have a significant effect on the bioaerosol distribution. After optimizing the layout arrangements of exhaust air, the aerosol concentration in the ward with the patient in both supine and sitting positions is significantly reduced with particle removal efficiencies exceeding 95%, that is, the ventilation performance is improved. Meanwhile, the proportion of aerosol deposition on all surfaces of the ward is decreased, especially the deposition on both the patient's body and the bed is less than 1%, implying that the risk of HCWs being infected through direct contact is reduced.

The airflow distribution and aerosol diffusion rules in the negative pressure isolation ward

Negative pressure wards are significant in preventing the spread of infectious pathogens which play a crucial role in fighting against COVID-19. Owing to the negative pressure, contaminated air with pathogens is not able to flow from the wards to non-contaminated zones while fresh filtered air will be transported to the ward via the ventilation system. As airflow controlled by ventilation systems affects the motion of pathogens, for example, infectious aerosol particles, the ability of a negative pressure ward to reduce the risk of infection highly relies on an effective ventilation system. In this investigation, impacts of airflow patterns under various human postures and ventilation processes aerosols diffusion are analyzed via the computational fluid dynamics (CFD) simulation. According to the results, among three airflow patterns, the highest contaminant removal efficiency is 57% at 200 s with the top supply and bottom return mode; besides, in three postures, in the case that the patient is in a standing position, the contaminant removal efficiency is the highest. Furthermore, it is found that the best airflow scheme is a slit tuyere in the ward, with a top supply and side return mode and a sitting position for the patient. This study may provide a reference for the design of airflow in negative pressure isolation wards, control of contaminants, and prevention of viral infections, so as to ensure a good working and recovery environment for medical staff and patients.

Contaminant removal effectiveness evaluation of ventilation, UR-UVGI, and air cleaner using CFD in negative pressure isolation ward

A negative pressure isolation ward (NPIW) is designed to create negative pressure to prevent the spread of airborne viruses. Therefore, it is necessary to increase the contaminant removal effect in the NPIW. To reduce indoor air contaminants, upper room-ultraviolet germicidal irradiation (UR-UVGI) and air cleaner are being used. Unlike the UR-UVGI, the air cleaner generates airflow. Therefore, the contaminant removal effect may differ according to the ventilation methods. This study is to compare ventilation, UR-UVGI, and air cleaner contaminant removal effects using CFD and Contaminant Removal Effectiveness (CRE) in the NPIW. As a result, the CRE of the ceiling and wall exhaust methods were different, and the CRE of the URUVGI and air cleaner cases were also different according to the two ventilation methods. Therefore, when applying UR-UVGI and air cleaner, it is necessary to consider the ventilation method.

Designing Mobile Epidemic Prevention Medical Stations for the COVID-19 Pandemic and International Medical Aid.

The demand for mobile epidemic prevention medical stations originated from the rapid spread of the COVID-19 pandemic. In order to reduce the infection risk of medical practitioners and provide flexible medical facilities in response to the variable needs of the pandemic, this research aimed to design mobile medical stations for COVID-19 epidemic prevention, the emergence of which began in February 2020. The mobile medical stations include a negative pressure isolation ward, a positive pressure swabbing station, a fever clinic and a laboratory. In Taiwan, many medical institutions used the mobile swabbing station design of this study to practice COVID-19 screening pre-tests. Internationally, this study assisted Palau in setting up medical stations to provide anti-epidemic goods and materials. The design of this study not only provides a highly flexible and safe medical environment but the benefits of screening can also be used as resources for medical research, forming an economic circulation for operation sustainability. In addition, the design of this study can also be used during the non-epidemic period as a healthcare station for rural areas or as a long-term community medical station.

Changes in blood pressure and related risk factors among nurses working in a negative pressure isolation ward.

ObjectiveTo observe changes in blood pressure (ΔBP) and explore potential risk factors for high ΔBP among nurses working in a negative pressure isolation ward (NPIW).MethodsData from the single-center prospective observational study were used. Based on a routine practice plan, female nurses working in NPIW were scheduled to work for 4 days/week in different shifts, with each day working continuously for either 5 or 6 h. BP was measured when they entered and left NPIW. Multivariable logistic regression was used to assess potential risk factors in relation to ΔBP ≥ 5 mm Hg.ResultsA total of 84 nurses were included in the analysis. The ΔBP was found to fluctuate on different working days; no significant difference in ΔBP was observed between the schedules of 5 and 6 h/day. The standardized score from the self-rating anxiety scale (SAS) was significantly associated with an increased risk of ΔBP ≥ 5 mm Hg (odds ratio [OR] = 1.12, 95% CI: 1.00–1.24). Working 6 h/day (vs. 5 h/day) in NPIW was non-significantly related to decreased risk of ΔBP (OR = 0.70), while ≥ 2 consecutive working days (vs. 1 working day) was non-significantly associated with increased risk of ΔBP (OR = 1.50).ConclusionThis study revealed no significant trend for ΔBP by working days or working time. Anxiety was found to be significantly associated with increased ΔBP, while no <2 consecutive working days were non-significantly related to ΔBP. These findings may provide some preliminary evidence for BP control in nurses who are working in NPIW for Coronavirus Disease 2019 (COVID-19).

Using CONTAM to design ventilation strategy of negative pressure isolation ward considering different height of door gaps

Infectious disease departments in hospitals require pressure gradient to create unidirectional airflow to prevent the spread of contaminants, typically by creating active air infiltration through the difference between supply and exhaust air volumes. The door gap is the channel of air flow between rooms, so its height has an important influence on the pressure difference and infiltration air volume of the room. There is still a lack of research on setting reasonable ventilation strategies according to the different heights of door gaps at different positions in the building. In this study, model of a set of isolation wards was established and analyzed using the multi-zone simulation software CONTAM, and the ventilation strategies with different heights of door gaps were applied to the actual infection diseases department. The results show that in a building with ventilation system divided by functional area, the difference in the height of the door gaps requires different active infiltration air volumes. Pressure fluctuations in the medical and patient corridors are greater than in other rooms. The significance of this study is to understand the active infiltration of air to guide the design and operation of ventilation systems in infectious disease hospitals or building remodeled to isolate close contacts of COVID-19 patients. It is also instructive for the design of pressure gradients in clean workshops, biological laboratories, and other similar buildings.

Droplet aerosols transportation and deposition for three respiratory behaviors in a typical negative pressure isolation ward

Negative pressure isolation wards could provide safety for health care workers (HCWs) and patients infected with SARS-CoV-2. However, respiratory behavior releases aerosols containing pathogens, resulting in a potential risk of infection for HCWs. In this study, the spatiotemporal distribution of droplet aerosols in a typical negative pressure isolation ward was investigated using a full-scale experiment. In this experiment, artificial saliva was used to simulate the breathing behavior, which can reflect the effect of evaporation on droplet aerosols. Moreover, numerical simulations were used to compare the transport of droplet aerosols released by the three respiratory behaviors (breathing, speaking, and coughing). The results showed that droplet aerosols generated by coughing and speaking can be removed and deposited more quickly. Because reduction in the suspension proportion per unit time was much higher than that in the case of breathing. Under the air supply inlets, there was significant aerosol deposition on the floor, while the breathing area possessed higher aerosol concentrations. The risk of aerosol resuspension and potential infection increased significantly when HCWs moved frequently to these areas. Finally, more than 20% of the droplet aerosols escaped from the ward when the number of suspended aerosols in the aerosol space was 1%.

Simulation study on the effect of air supply and exhaust terminals to coughed droplet diffusion in NPI ward

The numerical (CFD) method is applied in this paper to investigate the nonuniformity of temperature and airflow filed, the spatial and temporal distribution of coughed droplet under stratum ventilation and mixing ventilation in the negative pressure isolation (NPI) ward. The influence of exhaust terminals number and location on the diffusion process of coughed droplet is analyzed under heating mode. The results show that the relative pollutant concentration in the breathing area of stratum ventilation is lower than that of mixing ventilation. When the air exhaust terminals are high from the ground and the number are small, it is more conducive to reduce the infection risk of medical staff. The deposition rate and suspension rate of stratum ventilation are higher than that of mixing ventilation, and the escape rate is lower. When the number of exhaust outlets is large and the location is high, the nonuniformity coefficient is the smallest and the deposition rate is the largest, which are 0.668, 0.029 and 91.4% respectively. The escape rate is higher when the number of exhaust outlets is small and the location is high, and the suspension rate is higher when the number of exhaust outlets is large and the location is low, which are 27.9% and 1.11% respectively.

Design characteristics on the indoor and outdoor air environments of the COVID-19 emergency hospital

According to the discussion of the design method and operational effect for Wuhan Huoshenshan Hospital, this paper summarized the design control points of indoor and outdoor environment of COVID-19 emergency hospital. Based on the design of Wuhan Huoshenshan Hospital, this paper analyzed and discussed the site design, building layout, three-zones and two-passages, the design scheme of the ventilation and air conditioning system for negative pressure ward and negative pressure isolation ward, air distribution, as well as some other key designs for COVID-19 emergency hospital. The design points were summarized and refined. The design methods and technology requirements of the COVID-19 emergency hospital were provided in this study, such as ventilation and air conditioning system setting, ventilation quantity of wards, pressure gradient control measures among different areas, upper and lower air distribution, filter setting mode and distance of air inlet and outlet, which could benefit to provide references for the design of similar projects in the future.

Multizone modeling of pressure difference control analyses for an infectious disease hospital

Infectious disease hospitals must maintain pressure differences among rooms to direct the airflow toward the negative pressure isolation ward (NPIW) to prevent the spread of airborne pathogens. However, their values cannot be maintained easily in dynamic situations, especially when the door to the isolation room is open. There is a lack of guidelines for how to cope with this situation. A variable air volume (VAV) damper is set in the exhaust duct of the NPIW attempts to achieve active control by VAV but is often set to deliver constant air volume (CAV) because of a lack of confidence in its controllability. In this study, models based on a real infectious disease hospital are built and verified by the multizone model on Modelica. An appropriate active pressure difference control strategy for VAVs in NPIW is explored and it is applied in a floor of hospital model to analyze the influence of pressure differences among multiple rooms by VAV operation. The results show that the pressure difference deviations can be reduced by 9.98%–25.73% for different leakage paths of the isolation room with this control strategy. The pressure differences among hospital are stable during the VAV operation in the usual dynamic scenario. The airtightness of the door at zones junctions and external windows needs to be reduced to strengthen their anti-interference ability of pressure difference. This study fills the gap of guidelines and provides a reference for the application of VAVs for active pressure difference control in infectious disease hospitals.

Potential risk analysis of medical staff when performing endotracheal intubation in negative pressure isolation ward

This study investigated, using validated computational fluid dynamics techniques, the potential infection risks to medical staff when performing endotracheal intubation in the negative pressure isolation ward during treatment of COVID-19 patients. The research first simulated the airflow distribution in negative pressure isolation ward and then examined the potential infection risks to medical staff under two different respiratory conditions of a patient (i.e. patient with endotracheal intubation and patient with normal respiration). The results revealed that medical staff have high possibility to be contracted when performing endotracheal intubation. Personal protective equipment during endotracheal intubation is thus critical to mitigate the potential infection risk to medical staff. Space position and body posture of the medical staff (e.g. standing upright and bent over) would influence the contamination risk. Higher infection risk was noted for the medical staff who performs endotracheal intubation as compared to the other who delivers assistance. A bent-over posture of the medical staff encounters more particle exposure due to a closer distance to the patient head as well as the unfavourable airflow pattern/direction. Protection by using a plastic aerosol box over the head of the patient was studied, which shows promising improvement by preventing more than 75% of virus particles from spreading around.

Application of Intelligent Equipment on Novel Coronavirus Pneumonia Designated Hospital

Objective: To explore the application of intelligent equipment in non-negative pressure isolation ward for COVID-19 patients. Method: From February 1 to March 17, 2020, intelligent equipment, such as communication interaction system, intelligent disinfection robot, delivering robot, were used in non- negative pressure isolation ward of COVID-19. With the help of communication interaction system to supervise the implementation of infection prevention and control, and observe the incorrect situation of pee use and personal behavior before and after the implementation. The disinfection robot and meal delivery robot were used in ward disinfection and life nursing combined with nursing practice. Result: Through the supervision of communication interaction system, the frequency of pee use and personal behavior was reduced. The frequency of bad articles before and after improvement was wearing protective clothing (2.80%/0.84%), taking off protective clothing (5.87%/0.84%), personal behavior observation (8.38%/1.90%), P < 0.01. The robot disinfected and delivered medicine for 912.5 h, saving 225 shifts of nursing staff. Conclusion: Intelligent equipment is a good option for infection control in isolation ward of COVID-19. It can not only reduce the workload of health workers, but also the cross-infection.

Evaluation of UR-UVGI System for Sterilization Effect on Microorganism Contamination in Negative Pressure Isolation Ward

A negative pressure isolation ward prevents the outflow of airborne microorganisms from inside the ward, minimizing the spread of airborne contamination causing respiratory infection. In response to recent outbreaks of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS), Korea has increased the number of these facilities. However, airborne contaminants that flow into the ward from adjacent areas may cause secondary harm to patients. In this study, the sterilization effect of upper-room ultraviolet germicidal irradiation (UR-UVGI) on microorganisms generated within the negative pressure isolation ward and those flowing inward from adjacent areas was evaluated through field experiments and computational fluid dynamics (CFD) analysis, to assess the potential of this approach as a supplementary measure to control such microorganisms. The sterilization effect was found to be not high because of high-level ventilation. CFD analysis under various conditions shows that the sterilization effect for indoor-generated microorganisms varies with the level of UV radiation, the source locations of the indoor-generated microorganisms, air supplies and exhausts, the UVGI system, and the airflow formed under the specified conditions. Our results show that when the UVGI system is installed in the upper part of the ward entrance, contaminated air from adjacent area is strongly sterilized.

Working in a danger zone: A qualitative study of Taiwanese nurses' work experiences in a negative pressure isolation ward

Hospital nurses are frontline health care workers in controlling the spread of infectious diseases. It is not known if nurses working in negative pressure isolation wards (NPIWs) are better prepared than before to safely care for patients with common infectious diseases. For this qualitative descriptive study, 10 nurses were interviewed in depth about their experiences caring for patients in an NPIW. Tape recordings were transcribed verbatim and analyzed by qualitative content analysis. The following 5 themes were identified: (1) complexity of patient care, (2) dissatisfaction with the quantity and quality of protective equipment, (3) shortage of nursing staff, (4) continued worries about being infected, and (5) sensitivity to self-protection. Our participants' anxiety and uncertainty about being infected in the NPIW were increased by the complexity of patients' health problems and organizational factors. To protect themselves against infection before and during patient care, participants also developed sensitivity to, concepts about, and strategies to improve self-protection. NPIW administrators should pay more attention to nurses' concerns about improving the NPIW working environment, supply good quality protective equipment, and provide appropriate psychologic support and ongoing education to ensure that nurses feel safe while working. This ongoing education should refresh and update nurses' knowledge about disease transmission, therefore decreasing unnecessary anxiety based on misunderstandings about becoming infected.