This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research article
Study on the purification effect of a pediatric isolation bed on the air in general hospital wards
Rong Zhou
Guangzhou Medical University
Corresponding Author
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Patients with acute infectious respiratory illness may emit bio-aerosols containing pathogens capable of infecting susceptible hosts, including other patients and healthcare workers. This study aimed to evaluate the purification effect of a pediatric isolation bed on aerosols and microorganisms in the air in experiment rooms and verify the purification efficiency in general wards.
Methods: Experiments were carried out in two settings: one with isolation bed and the other with regular bed. Using a dust particle counter to discriminate particles sizes in the air and using Anderson’s six levels to discriminate S. albicans, the purification rate in the two rooms was evaluated. The concentration of cigarette particles(size 0.3–0.5 μm,0.5-1.0μm ) and S. albicans in the air was significantly decreased in the experimental room, indicating that the air was purified. Then detection the aerosol in the room to vilidaty the purification rate.Finally detection of aerosol and sedimentation bacteria in the air of general wards.
Results: Isolation beds in demonstration ward have a purifying effect on both aerosols and sedimentation bacteria.
Conclusions:Isolation bed can therefore be used in hospitals to reduce the risk of nosocomial infection and protect the health of doctors, patients, and visiting relatives.
Keywords
Pediatric isolation bed, purification effect, nosocomial infection, particulate, aerosol, bacteria
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
2.1. Material and equipment
Sustained release Staphylococcus albicans was purchased from the Microbiology Institute of Guangdong (Guangdong, China). Cigarettes (brand: Hongtashan, Yunnan, China) were purchased from a local retailer. A Y09-301 laser dust particle counter and an Anderson six-level sampler were both purchased from Sujin (Jiangsu, China).
2.2. Pediatric Isolation bed
Pediatric Isolation bed (Angelbiosafety, Guangzhou, China) are supplied in three gears: high-gear (the wind speed of the negative pressure port: 0.8 m/s), middle-gear (0.5–0.6 m/s), and low-gear (0.3–0.4 m/s), and can be operated closed (0 m/s) as a control. The centrifugal fan works to generate negative pressure and any infectious microorganisms such as bacteria and viruses in the air exhaled by the patient are captured by the sterilization filter unit, and the resulting clean air passes through the air outlet from the bedside cabinet.
2.3. Test the purification effect of the isolate bed in the experiment room.
Two experiment rooms, containing no patients, were set up in the laboratory as the experimental group and the control group. Each room had the following dimensions: 3.63 × 4.26 × 2.8 m (length, width, and height; Fig 1). A pediatric isolation bed (left in Fig 1) was placed in the experimental group room, and a standard hospital bed was placed in the control room. According to the five-point layout method[21], five sampling points (A,B,C,D,E)were selected that were arranged according to the positions shown in Fig 1A. The horizontal distances from the wall were greater than 1 m, and the vertical distance from the ground was about 140 cm. All tests were performed at 25°C–26°C, and the doors, windows, and air conditioners were all closed/off during the test.
2.4. Verification the purification effect of the isolation bed in hospital.
Two general wards were set up in the pediatric ward of Guangzhou Chest Hospital as the model and control wards. The Guangzhou Chest Hospital ward had the following dimensions: 5.7 × 3.3 × 2.8 m (length, width and height; Fig 2). Three pediatric isolation beds (shown in Fig 1B) were placed in the model ward, and three standard hospital beds were placed in the control ward. According to the five-point layout method[21], five sampling points(A,B,C,D,E) were selected, the positions of which are shown in Fig 2A. The horizontal distances from the wall were greater than 1 m, and the vertical distance from the ground was about 140 cm. The size, area, layout, and orientation of the control ward and the model ward were identical.
All tests were performed at 25°C–26°C, and the doors, windows, and air conditioners were all closed/off during the test.
2.5. Particle purification effect
(1) A cigarette was lit at point C in Fig 1A and left to burn for 15 min. After sufficient inhalable particles had been produced, the cigarette was extinguished. The electric fan was then turned on, adjusted to low wind speed, and left for 2 min to evenly distribute the inhalable particles throughout the room. The fan was then stopped and after a 3-min rest, samples were taken from the five sampling points indicated in Fig 1A. The Y09-301 laser dust particle counter was used at 2.83 L/min according to the "Test Method for Suspended Particles in the Cleanroom (Zone) of the Pharmaceutical Industry" GB/T16292-1996 standard. The flow rate was measured for the number of particles according to the six size ranges in the air in the room, pumping for 20 s at a time, and each point was continuously sampled three times and the average value was taken. Data were recorded every 10 min for 1 h. The total number of particles with a diameter of 0.3- 0.5 μm and 0.5–1.0 μm equated to the number of dust particles of this size. The above-mentioned experiment was carried out in a closed state (as the control), and at high-gear, mid-gear, and low-gear, and data were recorded for each gear position. Using these data, curves of particle size (0.3–0.5 μm and 0.5–1.0 μm) against time were plotted. The particle (0.3–0.5 μm and 0.5–1.0 μm) purification rate for each sampling point for each gear position was calculated separately.
(2)The doors and windows of the room were opened for 24 h to allow for air flow into the room and the concentration of particulate matter in the ward stabilized. Then, the doors and windows were closed and the isolation bed run with low gear, at the same time,using the dust particle counter to sample the air at five sampling points with a flow rate of 2.83 L/min and a sampling time of 20 s. The average concentration of particulate matter at each point was based on three consecutive sampling times, and one round of sampling was undertaken every 10 min for 2 h of continuous sampling to observe changes in the distribution and concentration of particulate matter of different particle sizes in the room.
2.6. Purification effect following the sustained release of Staphylococcus albicans
(1) Experimental preparation: S. albicans was inoculated into an enriched culture medium and was cultured in an incubator at 37℃ for 24 h to enrich the bacteria. PBS was used for the preparation and dilution of bacteria, and S. albicans bacterial suspensions of known concentration were prepared using a spectrophotometer.
(2) Experimental group: the prepared bacterial suspension was added to the microbial aerosol generator and placed in the center of the ward to be opened for 15 min. The fan was turned on for 3 min, dispersing indoor microbial aerosols. The fan was then turned off and after a 2-min rest to allow for stabilization of the microbial concentration across the room, samples were taken from five sampling points set in the diagonal corners and the center of the room (>0.5 m from the wall, and ~1.4 m from the floor). The Anderson six-level sampler was used to collect and determine the initial concentration of microorganisms in the room at a flow rate of 28.3 L/min for 1 min. Samples were taken from room with the isolation gives 3 different gear (high-gear, medium-gear, and low-gear) after opening for 30 and 60 min. The sample plate was placed in an incubator at 37°C for 24 h to count the colonies and calculate the concentration of microorganisms in the air.
(3) Control group experiment: The method is similar to the Experimental group, but with an ordinary hospital bed.
(4) Data calculation
The microbial/particulate purification rate of the open isolation bed was calculated according to the equation:
[Due to technical limitations, the formula could not be displayed here. Please see the supplementary files section to access the formula.]
where, K is the purification rate, C0 is the initial air microbial/particulate concentration, and Ct is the air microbial/particulate concentration after opening the isolation bed for min.
2.7. Verify the purification efficiency in general wards.
(1) Experimental preparation: Prepare two wards which gives the same size, layout and orientation, one for demonstration ward and the other for control ward. Five sampling points were set up at the diagonal points in the ward and the center of the ward, which were more than 0.5 m from the wall horizontally, and about 1.4 m from the floor vertically. The indoor temperature and humidity were monitored and maintained at a constant level.
(2) Demonstration ward: There are 3 isolation bed in the demonstration ward. The isolation bed runs uninterrupted with a low gear. A child with a respiratory illness lives on each isolation bed, and each child has an adult caregiver. So there are 3 child patients and 3 adult caregivers in the demonstration ward. The doors and windows of the ward were closed for 2 h before test to allow the stability of the sampling. Samples were taken from five sampling points set in the diagonal corners and the center of the room (>0.5 m from the wall, and ~1.4 m from the floor) (fig 1B).The dust particle counter were used to sample the air at five sampling points with a flow rate of 2.83 L/min and a sampling time of 20 s. The average concentration of particulate matter at each point was based on three consecutive sampling times.
The Anderson six-level sampler was used to collect and determine the initial concentration of settlement bacteria in the room at a flow rate of 28.3 L/min for 40 min. Repeat three times for each sample. Samples were taken from ward with the isolation gives low-gear. The sample plate was placed in an incubator at 37°C for 24 h to count the colonies and calculate the concentration of settlement bacteria in the air.
(3) Control experiment: The method is similar to the Experimental group, but with an ordinary hospital bed.
(4) Data calculation
This followed the same procedure as section 2.6.
2.8. Statistical analysis
Statistical analysis of the result was performed using Prism 7 software (GraphPad). Statistics analyses for other experiments were performed using t-test. P values (P) less than 0.05 were considered statistically significant.
This is a list of supplementary files associated with this preprint. Click to download.
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 23 Dec, 2019
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Infectious Diseases
Learn more about our company.
This is a preprint. It has not completed peer review.
Research article
Study on the purification effect of a pediatric isolation bed on the air in general hospital wards
Rong Zhou
Guangzhou Medical University
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 23 Dec, 2019
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Infectious Diseases
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Background: Patients with acute infectious respiratory illness may emit bio-aerosols containing pathogens capable of infecting susceptible hosts, including other patients and healthcare workers. This study aimed to evaluate the purification effect of a pediatric isolation bed on aerosols and microorganisms in the air in experiment rooms and verify the purification efficiency in general wards.
Methods: Experiments were carried out in two settings: one with isolation bed and the other with regular bed. Using a dust particle counter to discriminate particles sizes in the air and using Anderson’s six levels to discriminate S. albicans, the purification rate in the two rooms was evaluated. The concentration of cigarette particles(size 0.3–0.5 μm,0.5-1.0μm ) and S. albicans in the air was significantly decreased in the experimental room, indicating that the air was purified. Then detection the aerosol in the room to vilidaty the purification rate.Finally detection of aerosol and sedimentation bacteria in the air of general wards.
Results: Isolation beds in demonstration ward have a purifying effect on both aerosols and sedimentation bacteria.
Conclusions:Isolation bed can therefore be used in hospitals to reduce the risk of nosocomial infection and protect the health of doctors, patients, and visiting relatives.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
2.1. Material and equipment
Sustained release Staphylococcus albicans was purchased from the Microbiology Institute of Guangdong (Guangdong, China). Cigarettes (brand: Hongtashan, Yunnan, China) were purchased from a local retailer. A Y09-301 laser dust particle counter and an Anderson six-level sampler were both purchased from Sujin (Jiangsu, China).
2.2. Pediatric Isolation bed
Pediatric Isolation bed (Angelbiosafety, Guangzhou, China) are supplied in three gears: high-gear (the wind speed of the negative pressure port: 0.8 m/s), middle-gear (0.5–0.6 m/s), and low-gear (0.3–0.4 m/s), and can be operated closed (0 m/s) as a control. The centrifugal fan works to generate negative pressure and any infectious microorganisms such as bacteria and viruses in the air exhaled by the patient are captured by the sterilization filter unit, and the resulting clean air passes through the air outlet from the bedside cabinet.
2.3. Test the purification effect of the isolate bed in the experiment room.
Two experiment rooms, containing no patients, were set up in the laboratory as the experimental group and the control group. Each room had the following dimensions: 3.63 × 4.26 × 2.8 m (length, width, and height; Fig 1). A pediatric isolation bed (left in Fig 1) was placed in the experimental group room, and a standard hospital bed was placed in the control room. According to the five-point layout method[21], five sampling points (A,B,C,D,E)were selected that were arranged according to the positions shown in Fig 1A. The horizontal distances from the wall were greater than 1 m, and the vertical distance from the ground was about 140 cm. All tests were performed at 25°C–26°C, and the doors, windows, and air conditioners were all closed/off during the test.
2.4. Verification the purification effect of the isolation bed in hospital.
Two general wards were set up in the pediatric ward of Guangzhou Chest Hospital as the model and control wards. The Guangzhou Chest Hospital ward had the following dimensions: 5.7 × 3.3 × 2.8 m (length, width and height; Fig 2). Three pediatric isolation beds (shown in Fig 1B) were placed in the model ward, and three standard hospital beds were placed in the control ward. According to the five-point layout method[21], five sampling points(A,B,C,D,E) were selected, the positions of which are shown in Fig 2A. The horizontal distances from the wall were greater than 1 m, and the vertical distance from the ground was about 140 cm. The size, area, layout, and orientation of the control ward and the model ward were identical.
All tests were performed at 25°C–26°C, and the doors, windows, and air conditioners were all closed/off during the test.
2.5. Particle purification effect
(1) A cigarette was lit at point C in Fig 1A and left to burn for 15 min. After sufficient inhalable particles had been produced, the cigarette was extinguished. The electric fan was then turned on, adjusted to low wind speed, and left for 2 min to evenly distribute the inhalable particles throughout the room. The fan was then stopped and after a 3-min rest, samples were taken from the five sampling points indicated in Fig 1A. The Y09-301 laser dust particle counter was used at 2.83 L/min according to the "Test Method for Suspended Particles in the Cleanroom (Zone) of the Pharmaceutical Industry" GB/T16292-1996 standard. The flow rate was measured for the number of particles according to the six size ranges in the air in the room, pumping for 20 s at a time, and each point was continuously sampled three times and the average value was taken. Data were recorded every 10 min for 1 h. The total number of particles with a diameter of 0.3- 0.5 μm and 0.5–1.0 μm equated to the number of dust particles of this size. The above-mentioned experiment was carried out in a closed state (as the control), and at high-gear, mid-gear, and low-gear, and data were recorded for each gear position. Using these data, curves of particle size (0.3–0.5 μm and 0.5–1.0 μm) against time were plotted. The particle (0.3–0.5 μm and 0.5–1.0 μm) purification rate for each sampling point for each gear position was calculated separately.
(2)The doors and windows of the room were opened for 24 h to allow for air flow into the room and the concentration of particulate matter in the ward stabilized. Then, the doors and windows were closed and the isolation bed run with low gear, at the same time,using the dust particle counter to sample the air at five sampling points with a flow rate of 2.83 L/min and a sampling time of 20 s. The average concentration of particulate matter at each point was based on three consecutive sampling times, and one round of sampling was undertaken every 10 min for 2 h of continuous sampling to observe changes in the distribution and concentration of particulate matter of different particle sizes in the room.
2.6. Purification effect following the sustained release of Staphylococcus albicans
(1) Experimental preparation: S. albicans was inoculated into an enriched culture medium and was cultured in an incubator at 37℃ for 24 h to enrich the bacteria. PBS was used for the preparation and dilution of bacteria, and S. albicans bacterial suspensions of known concentration were prepared using a spectrophotometer.
(2) Experimental group: the prepared bacterial suspension was added to the microbial aerosol generator and placed in the center of the ward to be opened for 15 min. The fan was turned on for 3 min, dispersing indoor microbial aerosols. The fan was then turned off and after a 2-min rest to allow for stabilization of the microbial concentration across the room, samples were taken from five sampling points set in the diagonal corners and the center of the room (>0.5 m from the wall, and ~1.4 m from the floor). The Anderson six-level sampler was used to collect and determine the initial concentration of microorganisms in the room at a flow rate of 28.3 L/min for 1 min. Samples were taken from room with the isolation gives 3 different gear (high-gear, medium-gear, and low-gear) after opening for 30 and 60 min. The sample plate was placed in an incubator at 37°C for 24 h to count the colonies and calculate the concentration of microorganisms in the air.
(3) Control group experiment: The method is similar to the Experimental group, but with an ordinary hospital bed.
(4) Data calculation
The microbial/particulate purification rate of the open isolation bed was calculated according to the equation:
[Due to technical limitations, the formula could not be displayed here. Please see the supplementary files section to access the formula.]
where, K is the purification rate, C0 is the initial air microbial/particulate concentration, and Ct is the air microbial/particulate concentration after opening the isolation bed for min.
2.7. Verify the purification efficiency in general wards.
(1) Experimental preparation: Prepare two wards which gives the same size, layout and orientation, one for demonstration ward and the other for control ward. Five sampling points were set up at the diagonal points in the ward and the center of the ward, which were more than 0.5 m from the wall horizontally, and about 1.4 m from the floor vertically. The indoor temperature and humidity were monitored and maintained at a constant level.
(2) Demonstration ward: There are 3 isolation bed in the demonstration ward. The isolation bed runs uninterrupted with a low gear. A child with a respiratory illness lives on each isolation bed, and each child has an adult caregiver. So there are 3 child patients and 3 adult caregivers in the demonstration ward. The doors and windows of the ward were closed for 2 h before test to allow the stability of the sampling. Samples were taken from five sampling points set in the diagonal corners and the center of the room (>0.5 m from the wall, and ~1.4 m from the floor) (fig 1B).The dust particle counter were used to sample the air at five sampling points with a flow rate of 2.83 L/min and a sampling time of 20 s. The average concentration of particulate matter at each point was based on three consecutive sampling times.
The Anderson six-level sampler was used to collect and determine the initial concentration of settlement bacteria in the room at a flow rate of 28.3 L/min for 40 min. Repeat three times for each sample. Samples were taken from ward with the isolation gives low-gear. The sample plate was placed in an incubator at 37°C for 24 h to count the colonies and calculate the concentration of settlement bacteria in the air.
(3) Control experiment: The method is similar to the Experimental group, but with an ordinary hospital bed.
(4) Data calculation
This followed the same procedure as section 2.6.
2.8. Statistical analysis
Statistical analysis of the result was performed using Prism 7 software (GraphPad). Statistics analyses for other experiments were performed using t-test. P values (P) less than 0.05 were considered statistically significant.