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Computational fluid dynamic simulations showing the airflow velocities of the three ventilation systems. The colours in the scale bar represent the different airflow velocities in m/s. The images in the left column are cross-sections of the operating room along the long side of the operating table, and the images in the right column are cross-sections of the operating room along the short side of the operating table. (a,b) Turbulent mixed airflow. (c,d) Laminar airflow. (e,f) Temperature-controlled airflow.
Source publication
Aim:
To evaluate three types of ventilation systems for operating rooms with respect to air cleanliness (in colony forming units, CFU/m(3)), energy consumption, and working environment comfort (noise and draught) as reported by surgical team members.
Methods:
Two commonly used ventilation systems, vertical laminar airflow (LAF) and turbulent mix...
Citations
... Within these classifications, many different designs exist for both TMA and UDAF ventilation systems. For instance, there are TMA systems with higher air flows, and laminar air flow systems with lower air flows [11]. The ISO 14644-1 classification is the international standard to describe the performance of different ventilation systems with regard to air cleanliness. ...
... The ISO 14644-1 classification is the international standard to describe the performance of different ventilation systems with regard to air cleanliness. Measured using the number of colonyforming units (CFUs), UDAF systems show better performance with regard to the bacteria concentration present in the OR [11,12]. However, there is controversy in the literature regarding whether UDAF actually reduces the incidence of SSI [13]. ...
... HVAC systems are responsible for 90e99% of energy consumption in ORs [27]. This energy consumption depends, amongst other things, on the type of air treatment system used [11,12]. Alsved et al. evaluated the air cleanliness and energy consumption of UDAF and TMA ventilation systems during orthopaedic operations. ...
Background: Surgical site infection (SSI) in the form of postoperative deep sternal wound infection (DSWI) after cardiac surgery is a rare, but potentially fatal, complication. In addressing this, the focus is on preventive measures, as most risk factors for SSI are not controllable. Therefore, operating rooms are equipped with heating, ventilation and air conditioning (HVAC) systems to prevent airborne contamination of the wound, either through turbulent mixed air flow (TMA) or unidirectional air flow (UDAF).
Aim: To investigate if the risk for SSI after cardiac surgery was decreased after changing from TMA to UDAF.
Methods: This observational retrospective single-centre cohort study collected data from 1288 patients who underwent open heart surgery over 2 years. During the two study periods, institutional SSI preventive measures remained the same, with the exception of the type of HVAC system that was used.
Findings: Using multi-variable logistic regression analysis that considered confounding factors (diabetes, obesity, duration of surgery, and re-operation), the hypothesis that TMA is an independent risk factor for SSI was rejected (odds ratio 0.9, 95% confidence interval 0.4e1.8; P>0.05). It was not possible to demonstrate the preventive effect of UDAF on the incidence of SSI in patients undergoing open heart surgery when compared with TMA. Conclusion: Based on these results, the use of UDAF in open heart surgery should be weighed against its low cost-effectiveness and negative environmental impact due to high electricity consumption. Reducing energy overuse by utilizing TMA for cardiac surgery can diminish the carbon footprint of operating rooms, and their contribution to climate-related health hazards.
... scoliosis), should be performed in an OR class1+ [4] . The indoor air quality of an OR class 1+ should comply to the internationally accepted definition of ultra clean air which is defined as air which contains less than 10 colony forming units per cubic meter of air (CFU/m 3 ) [5][6][7][8][9] . This in line, for infection prone surgery, with international standards and guidelines [10][11][12][13] as well as with the recommendation of the Dutch Orthopedic Association (NOV) [14] . ...
Background
The operating room (OR) department is one of the most energy-intensive departments of a hospital. The majority of ORs in the Netherlands have an air handling installation with an ultra-clean ventilation (UCV) system. However, not all surgeries require an ultra-clean operating room.
Aim
What is the effect of reducing the air change rate on the ventilation effectiveness in ultra-clean operating rooms?
Methods
In this study lower airvolume ventilation effectiveness (VELv) of a Conventional Ventilation (CV), controlled Dilution Ventilation (cDV), Temperature controlled AirFlow (TcAF) and Uni Directional AirFlow (UDAF) system was evaluated and measured within a 4x4 meter square measuring grid of 1x1 meter. The VELv is defined as the recovery degree (RD), cleanliness recovery rate (CRR) and air change effectiveness (ACE).
Findings
The CV, cDVLv and TcAFLv ventilation systems show a comparable mixing character in Area A, B and AB when reducing the air change rate to 20h-1. Ventilation effectiveness decreases when the air change rate is reduced, with exception of the ACE.
At all points for the UDAF-2Lv and at the center point (C3) of the TcAFLv, higher RD10Lv and CRRLv were measured when compared to the other examined ventilation systems.
Conclusion:
The ventilation effectiveness decreases when an ultra-clean OR with an ultra-clean ventilation air supply system is switched to an air change rate of 20h-1. Reducing the air change rate in the OR from an ultra-clean OR to a generic OR will reduce the recovery degree (RD10) with a factor 10 to 100 and the local air change rate (CRR) between 42%-81%.
... Active sampling methods, such as air-pumped samplers, are also widely applied in the monitoring of indoor air pollutants including microbes (Alsved et al., 2018), nitrogen dioxide (Staimer et al., 2005), particulate matter (Miller et al., 2019;Taghvaee et al., 2019), and volatile organic compounds (Huang et al., 2018), among others. The system consists of a pump sampler and a replaceable device with a filter that passes a known volume of air through a collection filter over a fixed period. ...
Airborne Microplastics (MPs), an emerging environmental issue, have gained recent attention due to their new-found presence in indoor environments. Utilizing the Web of Science database for literature collection, the paper presents a comprehensive review of airborne MPs including emission sources, assessment methods, exposure risks, and mitigation strategies. This review delves into the diverse sources and mechanisms influencing indoor airborne MP pollution, underscoring the complex interplay between human activities, ventilation systems, and the characteristics of indoor environments. Major sources include the abrasion of synthetic textiles and the deterioration of flooring materials, with factors like carpeting, airflow, and ventilation significantly impacting MP levels. Human activities, such as increased movement in indoor spaces and the intensive use of plastic-based personal protective equipment (PPE) post-pandemic, notably elevate indoor MP concentrations. The potential health impacts of airborne MPs are increasingly concerning, with evidence suggesting their role in respiratory, immune, and nervous system diseases. Despite this, there is a scarcity of information on MPs in diverse indoor environments and the inhalation risks associated with the frequent use of PPE. This review also stresses the importance of developing effective strategies to reduce MP emissions, such as employing HEPA-filtered vacuums, minimizing the use of synthetic textiles, and enhancing indoor ventilation. Several future research directions were proposed, including detailed temporal analyses of indoor MP levels, interactions of MP with other atmospheric pollutants, the transport dynamics of inhalable MPs (≤10 μm), and comprehensive human exposure risk assessments .
... The findings revealed that TcAF and LAF were more effective than TMA in reducing airborne bacteria, especially near wounds and instrument tables. The unique TcAF ventilation system, similar to LAF, consistently maintains a low level of colony-forming bacteria per unit volume in the air and establishes an improved working environment for healthcare personnel [70]. According to Moreno et al., it is advisable to implement unidirectional airflow in the surgical area to ensure the presence of clean air near the patient and minimize the occurrence of dust, particulate matter (PM), and other pollutants that can cause respiratory discomfort for healthcare workers and patients. ...
The creation of a welcoming hospital atmosphere is necessary to improve patient wellbeing and encourage healing. The goal of this study was to examine the variables affecting hospitalised patients' comfort. The study procedure included a thorough search of the Web of Science and Scopus databases, as well as the use of software analytic tools to graphically map enormous literature data, providing a deeper understanding of the linkages within the literature and its changing patterns. Insights from a range of disciplines, including engineering, psychology, immunology, microbiology, and environmental science, were included into our study using content analysis and clustering approaches. The physical environment and the social environment are two crucial factors that are related to patient comfort. The study stress the need of giving patient comfort a top priority as they heal, especially by tackling indoor air pollution. Our research also emphasises how important hospital care and food guidelines are for improving patient comfort. Prioritising patients who need specialised care and attention, especially those who have suffered trauma, should be the focus of future study. Future research in important fields including trauma, communication, hospital architecture, and nursing will be built on the findings of this study. To enhance research in these crucial areas, worldwide collaboration between experts from other nations is also advised. Although many studies stress the significance of patient comfort, few have drawn conclusions from a variety of disciplines, including medicine, engineering, immunology, microbiology, and environmental science, the most crucial issue of thoroughly researching the improvement of patient comfort has not been addressed. Healthcare workers, engineers, and other professions will benefit greatly from this study's investigation of the connection between hospital indoor environments and patient comfort.
... Many studies have tried adjusting different air quality variables in the operating room to reduce air contamination. These include different airflow patterns (i.e., temperaturecontrolled, laminar, and turbulent mixed), as well as traffic flow in the operating room, the number of door openings during surgery, and UV air filtration [6][7][8][9][10][11][12][13]. Determining how to minimize aerosol contamination during total joint arthroplasty is of great importance due to its impact on infection rate. ...
... Previous studies have examined other operating room variables and their effects on air quality. Alsved et al. found that temperature-controlled airflow and vertical laminar airflow are superior to turbulent mixed airflow in removing bacteria from the air [6]. Anderson et. ...
Introduction
Operating room air quality can be affected by several factors including temperature, humidity, and airborne particle burden. Our study examines the role of operating room (OR) size on air quality and airborne particle (ABP) count in primary total knee arthroplasty (TKA).
Materials and methods
We analyzed all primary, elective TKAs performed within two ORs measuring 278 sq ft. (small) and 501 sq ft. (large) at a single academic institution in the United States from April 2019 to June 2020. Intraoperative measurements of temperature, humidity, and ABP count were recorded. p values were calculated using t test for continuous variables and chi-square for categorical values.
Results
91 primary TKA cases were included in the study, with 21 (23.1%) in the small OR and 70 (76.9%) in the large OR. Between-groups comparisons revealed significant differences in relative humidity (small OR 38.5% ± 7.24% vs. large OR 44.4% ± 8.01%, p = 0.002). Significant percent decreases in ABP rates for particles measuring 2.5 μm (− 43.9%, p = 0.007) and 5.0 μm (− 69.0%, p = 0.0024) were found in the large OR. Total time spent in the OR was not significantly different between the two groups (small OR 153.09 ± 22.3 vs. large OR 173 ± 44.6, p = 0.05).
Conclusions
Although total time spent in the room did not differ between the large and small OR, there were significant differences in humidity and ABP rates for particles measuring 2.5 μm and 5.0 μm, suggesting the filtration system encounters less particle burden in larger rooms. Larger studies are required to determine the impact this may have on OR sterility and infection rates.
... Such monitoring has been done by the operating room or by a combination of the operating room and specialty, and not by the patient. Furthermore, operating rooms differ in their number of air changes per hour, ceiling air diffuser designs, room geography, and types of airflow (e.g., laminar or turbulent) [7][8][9][10][11][12]. Such differences may be associated with inequality in surgical site infection rates among rooms [13]. ...
... (The reason is the large inequality among locations in cases per quarter.) Our results show that modifying operating room airflow (e.g., changing to single large diffusers in procedural rooms) [7][8][9][10][11][12][13], changing door signage and locks [14], selecting anesthesia machines for purchase in part based on ease of decontamination [15], or applying ultraviolet-C disinfection at the end of each workday [16,17] for all procedural locations would have lowcost utility for many organizations, at best, if the technologies were effective at preventing infections. ...
Background
Earlier studies have shown that prevention of surgical site infection can achieve net cost savings when targeted to operating rooms with the most surgical site infections.
Methodology
This retrospective cohort study included all 231,057 anesthetics between May 2017 and June 2022 at a large teaching hospital. The anesthetics were administered in operating rooms, procedure rooms, radiology, and other sites. The 8,941 postoperative infections were identified from International Classification of Diseases diagnosis codes relevant to surgical site infections documented during all follow-up encounters over 90 days postoperatively. To quantify the inequality in the counts of infections among anesthetizing locations, the Gini index was used, with the Gini index being proportional to the sum of the absolute pairwise differences among anesthetizing locations in the counts of infections.
Results
The Gini index for infections among the 112 anesthetizing locations at the hospital was 0.64 (99% confidence interval = 0.56 to 0.71). The value of 0.64 is so large that, for comparison, it exceeds nearly all countries’ Gini index for income inequality. The 50% of locations with the fewest infections accounted for 5% of infections. The 10% of locations with the most infections accounted for 40% of infections and 15% of anesthetics. Among the 57 operating room locations, there was no association between counts of cases and infections (Spearman correlation coefficient r = 0.01). Among the non-operating room locations (e.g., interventional radiology), there was a significant association (Spearman r = 0.79).
Conclusions
Targeting specific anesthetizing locations is important for the multiple interventions to reduce surgical site infections that represent fixed costs irrespective of the number of patients (e.g., specialized ventilatory systems and nightly ultraviolet-C disinfection).
... Laminar flow is also broadly utilized to sustain cleanliness in various industries, such as biological and microelectronic manufacturing [31,32], food production [33,34], and hospital operating rooms [35,36]. The design of flow channels, such as wall-return [37], celling return [38], and radial [39], contributes to the parallel and perpendicular flow of air, providing different levels of protection. ...
... Time to Reach Re = 1 in the x-Direction (s) <10 (5) 7.77 × 10 −4 9.62 × 10 −4 10-20 (15) 7.00 × 10 −3 6.04 × 10 −3 20-30 (25) 1.94 × 10 −2 1.63 × 10 −2 30-40 (35) 3.81 × 10 −2 3.34 × 10 −2 40-50 (45) 6.30 × 10 −2 5.37 × 10 −2 >50 (75) 1.75 × 10 −1 1.45 × 10 −1 ...
In high-power laser systems, the primary cause of contamination of optical components and degradation of spatial cleanliness is laser-induced sputtering of particles. To mitigate this problem, laminar flow is frequently utilized to control the direction and transport of these particles. This study characterizes the properties of laser-induced sputtering particles, including their flying trend, diameter range, and velocity distribution at varying time intervals. A time-resolved imaging method was employed to damage the rear surface of fused silica using a 355 nm Nd: YAG pump laser. The efficacy of laminar flow in controlling these particles was then assessed, with a particular focus on the influence of laminar flow direction, laminar flow velocity, particle flight height, and particle diameter. Our results indicate that the optimal laminar flow velocity for preventing particle invasion is highly dependent on the maximum particle attenuation distance (or safety distance), which can vary by up to two orders of magnitude. Furthermore, a laminar flow velocity of 0.5 m/s can effectively prevent particle sedimentation. Future research will aim to optimize laminar flow systems based on these findings to achieve high surface cleanliness in high-power laser systems with minimal energy consumption.
... The difference in IL-6 delta results obtained in the regular bus group compared to the Biosmart and safe bus is influenced by several factors, including the concept used in laminar air circulation in the Biosmart and safe bus can reduce pathogenic injury which can prevent a higher increase in IL-6 levels, lower than the increase in IL-6 levels on regular buses. This study is in line with research on the difference between turbulent airflow and laminar airflow applied to hospital operating rooms [19]. The laminar air flow technique is proven to be more efficient inhibiting the spread of bacteria compared to turbulent air flow [19]. ...
... This study is in line with research on the difference between turbulent airflow and laminar airflow applied to hospital operating rooms [19]. The laminar air flow technique is proven to be more efficient inhibiting the spread of bacteria compared to turbulent air flow [19]. ...
... Horizontal LAF systems are less expensive to install and maintain than ceiling (vertical) LAF systems [8]. Temperature-controlled airflow (TcAF) is a recently developed and validated air distribution technique [9,10]. Unlike HLAF and VLAF ventilations, TcAF ventilation provides clean air at varying temperatures and controls air movement based on temperature. ...
... Variations in the velocity and direction of airflow caused by the location of the supply air and the exhaust air affected the risk of virus transmission across the hospital. Alsved et al. [9] compared three types of operating room ventilation systems in terms of air cleanliness in colony-forming units (CFU/m3), working environment comfort, and energy consumption. They discovered that TcAF and LAF eliminate bacteria from the air more effectively than TMA. ...
... This paper presents three ventilation systems (VLAF, HLAF, and TcAF) from five experiments applied to the exhausted air of four Table 1 Description, Geometry information of objects, and boundary conditions. It is also known as unidirectional airflow, and forces air through HEPA filters in the ceiling at a high airflow rate, achieving a vertical speed of 0.3 m/s [9]. Warmer HEPA-filtered air is dispersed from eight additional ceiling air diffusers around the cooled center airflow. ...
The risk of healthcare-associated infections (HAIs) is higher in patients admitted to intensive care units (ICU) and high dependency units (HDU). Currently, most ventilation studies focus on specialized areas, mainly isolation rooms and operating rooms. This paper focuses on the ventilation of multiple-bed hospital wards in developing countries. This study uses computational fluid dynamics (CFD) simulation to model and investigate airflow and the spread of pollutants. The study aims to investigate ICUs with various ventilation system designs. These predicted behaviors and characteristics were compared numerically to determine compliance with the requirements of airflow patterns, airborne contaminant distribution, and current international standards. The case study simulations were carried out using ANSYS Fluent simulation software as a solution tool. Three different ventilation systems, Vertical Laminar Airflow Ventilation (VLAF), Horizontal Laminar Airflow Ventilation (HLAF), and Temperature-Controlled Airflow Ventilation (TcAF), were modeled within five different designs to determine the most effective possible distribution of air inside the patient's room, based on different categories, primarily temperature distribution, CO2 concentration, and airflow distribution. The authors applied the TcAF technique in an ICU room, comparing the results of the proposed technique with those of other common techniques (HLAF and VLAF). It was found that TcAF showed the most effective airflow distribution around patients, isolating each patient from the others. However, the temperature distribution was excluded from the ASHRAE standard. HLAF with two exhausts is the most suitable option, with a lower CO2 concentration than the alternatives and a temperature that meets ASHRAE standards.
... The difference in IL-6 delta results obtained in the regular bus group compared to the Biosmart and safe bus is influenced by several factors, including the concept used in laminar air circulation in the Biosmart and safe bus can reduce pathogenic injury which can prevent a higher increase in IL-6 levels, lower than the increase in IL-6 levels on regular buses. This study is in line with research on the difference between turbulent airflow and laminar airflow applied to hospital operating rooms [19]. The laminar air flow technique is proven to be more efficient inhibiting the spread of bacteria compared to turbulent air flow [19]. ...
... This study is in line with research on the difference between turbulent airflow and laminar airflow applied to hospital operating rooms [19]. The laminar air flow technique is proven to be more efficient inhibiting the spread of bacteria compared to turbulent air flow [19]. ...
The inhalant increasing risk of transmission in public transportation, is buses. Biosmart and safe bus apply the principle that the bus compartment which is a biological environment must be in a balanced state according to the disease triangle concept that is influenced by the host, in this case is the passenger, the agent causing the infection is a virus and the environment is the room in the bus cabin. The aim of the present study is to analyze the differences in IgA and IL-6 levels of Biosmart and safe bus passengers and regular bus passengers. This research is a non-blinded randomized control trial with pre-posttest design. Seventy passengers were randomly separated into two groups. Control group (n = 35) uses regular bus, and intervention group uses Biosmart and safe bus (n = 35). Nasal wash was taken by ENT specialists, and the levels of Sinonasal IgA and IL-6 were interpreted by ELISA. The data were analyzed by using Mann Whitney, Wilcoxon, Independent t-test and Paired t-test. The results is sinonasal IgA level got significant increase in all groups, respectively on pretest-posttest of intervention group 17,89 ± 30,19 (p = 0,021), control group 30,18 ± 76,09 (p = 0,014) while the delta IgA level on control group and intervention group resulted in no significant difference (p = 0,182). The IL-6 level also increased in all groups with significant difference (p = 0.000), the delta resulted in significant difference (p = 0,013) with intervention group 13,38 ± 0,96 and control group 13,90 ± 1,27. Interleukin-6 sinonasal levels of Regular Bus and Biosmart and Safe Bus passengers show difference with higher
