Laminar Air Flow System Research Articles

Surgical smoke: a matter of hygiene, toxicology, and occupational health.

The use of devices for tissue dissection and hemostasis during surgery is almost unavoidable. Electrically powered devices such as electrocautery, ultrasonic and laser units produce surgical smoke containing more than a thousand different products of combustion. These include large amounts of carcinogenic, mutagenic and potentially teratogenic noxae. The smoke contains particles that range widely in size, even as small as 0.007 µm. Most of the particles (90%) in electrocautery smoke are ≤6.27 µm in size, but surgical masks cannot filter particles smaller than 5 µm. In this situation, 95% of the smoke particles which pass through the mask reach deep into the respiratory tract and frequently cause various symptoms, such as headache, dizziness, nausea, eye and respiratory tract irritation, weakness, and abdominal pain in the acute period. The smoke can transport bacteria and viruses that are mostly between 0.02 µm and 3 µm in size and there is a risk of contamination. Among these viruses, SARS-CoV-2, influenza virus, HIV, HPV, HBV must be considered. The smoke may also carry malignant cells. The long-term effects of the surgical smoke are always ignored, because causality can hardly be clarified in individual cases. The quantity of the smoke changes with the technique of the surgeon, the room ventilation system, the characteristics of the power device used, the energy level at which it is set, and the characteristics of the tissue processed. The surgical team is highly exposed to the smoke, with the surgeon experiencing the highest exposure. However, the severity of exposure differs according to certain factors, e.g., ventilation by laminar or turbulent mixed airflow or smoke evacuation system. In any case, the surgical smoke must be removed from the operation area. The most effective method is to collect the smoke from the source through an aspiration system and to evacuate it outside. Awareness and legal regulations in terms of hygiene, toxicology, as well as occupational health and safety should increase.

The Anti-microbial Activity of Polyherbal Extract using Escherichia Coli and Saccharomyces Cerevisiae

One of the biggest issues in contemporary life is antimicrobial resistance. Therefore, a remedy to this issue is required. Combinations of various antimicrobial medications ought to be more effective than single medications. The usual plants that grow in our area have antibacterial properties. One of the main plants with strong antibacterial action is Azadirachta indica. Eryngium foetidum and Mimosa pudica both have demonstrated antibacterial action and are readily available. The combination of these three herbal plants extracts ought to provide stronger antibacterial effects than any of the plants separate extracts. Raw plants are initially gathered from the area. The Azadirachta indica, Eryngium foetidum, and Mimosa pudica leaves and roots are employed. To get rid of dirt and undesired detritus, plants are thoroughly washed and dried in the shade. The plant leaves are then thoroughly pulverized individually. Then, using a Soxhlet device and ethanol the powdered plants are extracted separately. The extraction process is carried out until a clear solution is found. The ethanol is then removed from the obtained extracts by evaporation. DMF (dimethyl formamide) is used to dilute the extract so that 1000mcg, 2000mcg, and 3000mcg of each plant extract and plant extract mixture is also prepared in three different concentrations. The Disc Plate method, which employs Saccharomyces cerevisiae and E. coli, is used for antimicrobial assay. It is decided to use nutrient agar for bacteria and sabouraud dextrose agar for fungi. The prepared substance discs dipped in plant extracts and a combination are then added to the inoculation medium in an aseptic space with a laminar airflow system after it has been first inoculated with the organisms. The plates are then left to incubate for 24 hours. The outcomes were as anticipated; the plant extract combo displayed a greater zone of inhibition than the plant extracts taken separately. It measures the zone of inhibition.

Air change per hour and inlet area: Effects on ultrafine particle concentration and thermal comfort in an operating room

The Heating, Ventilation and Air Conditioning (HVAC) system in an Operating Room (OR) has two main functions: evacuate contaminants to guarantee an elevated Indoor Air Quality (IAQ) and ensure the thermal comfort of the occupants. The UltraFine Particles (UFP) generated during the surgical operation can cause health-related risks at higher concentrations if inhaled for a prolonged time. In this work, the authors have developed a transient model to simulate the thermofluid dynamic conditions, UFP transport and thermal comfort inside an OR equipped with a Laminar AirFlow (LAF) system. The effects of the Air Change per Hour (ACH) and inlet area on the unidirectional airflow, UFP concentration and thermal comfort have been studied here for the first time, considering the constraints imposed by the standards. An increase of ACH above the minimum value imposed by the standards can ensure two advantages: obtaining both thermal comfort conditions for the surgical staff and very low UFP concentrations. Moreover, larger ACH values ensure the unidirectional airflow and avoid the disruption caused by the thermal plume. Excessive ACH values do not bring additional cleanness to the OR, while increasing energy consumption.

Cross-Sectional Study to Evaluate Infection in Operation Theater and Difference in Infection Pattern Between Laminar Air Flow and Non-Laminar Air Flow Operation Theaters

This was a cross-sectional study to compare the infection rate between laminar air flow and non-laminar air flow operation theater (OT). This was bi-center study and study places were the OT complexes of Sylhet Women’s Medical College Hospital (SWMCH) and Al Haramain Hospital Pvt. Ltd. of Sylhet. A Total 24 samples were collected from 12 OTs. Air and wall swab both types of samples were collected from each OT. Out of these 12 OTs 4 had laminar air flow system. Half of the air samples (50%) and 8.3% of wall samples were infected, whereas overall organism isolation rate was 29.17%. Among all the infected samples 25% were from laminar air flow OTs and the rest 75% were from non-laminar air flow OTs. Commonest isolated bacteria was staphylococcus epidermidis (62.5%) followed by bacillusspp (25%) and staphylococcus aureus (12.5%). staphylococcus epidermidis was predominantly found in General Surgery, Obstetrics and septic OTs. Distance from entry or toilet did not show any significant difference in infection rate in operation theaters.

A vertical laminar airflow system to prevent aerosol transmission of SARS-CoV-2 in building space: Computational fluid dynamics (CFD) and experimental approach

Respiratory aerosol particles carrying the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) are a primary cause of the long-distance infection, and insufficient ventilation systems make building occupants highly prone to the coronavirus disease-2019 (COVID-19). As a preventive measure of the aerosolized viable SARS-CoV-2 suspension in building space, we seek to propose an optimal design of the upper-room/drop-ceiling aeration grid system generating vertical laminar airflow (VLAF) as an aerosol barrier. On a test plan (6.1 × 4.7 m) representing the standard hospital patient room in South Korea (a 2.7 m-height room of 77.4 m3 in volume), we investigated the air-terminal size, spacing and air speed that shape uniform downflow of fresh air, minimizing horizontal spread. Our simulation results using the Taguchi method and computational fluid dynamics (CFD) in presence of indoor human expiration indicated that a steady vertical air supply of 0.3 m/s through 0.04m-diameter air diffusers deployed by 0.5 m spacing is the most effective to form VLAF. Physical particle detection tests at the height of 1.5 m in mockup setting of the optimal system design, revealed that expiratory aerosols produced by a single person were almost entirely removable in 20 s. Investigations also confirmed that the proposed design could minimize stagnant airflow regions and would potentially satisfy the indoor air-speed condition for occupant thermal comfort.

A systematic review and meta-analysis of indoor bioaerosols in hospitals: The influence of heating, ventilation, and air conditioning.

To evaluate (1) the relationship between heating, ventilation, and air conditioning (HVAC) systems and bioaerosol concentrations in hospital rooms, and (2) the effectiveness of laminar air flow (LAF) and high efficiency particulate air (HEPA) according to the indoor bioaerosol concentrations. Databases of Embase, PubMed, Cochrane Library, MEDLINE, and Web of Science were searched from 1st January 2000 to 31st December 2020. Two reviewers independently extracted data and assessed the quality of the studies. The samples obtained from different areas of hospitals were grouped and described statistically. Furthermore, the meta-analysis of LAF and HEPA were performed using random-effects models. The methodological quality of the studies included in the meta-analysis was assessed using the checklist recommended by the Agency for Healthcare Research and Quality. The mean CFU/m3 of the conventional HVAC rooms and enhanced HVAC rooms was lower than that of rooms without HVAC systems. Furthermore, the use of the HEPA filter reduced bacteria by 113.13 (95% CI: -197.89, -28.38) CFU/m3 and fungi by 6.53 (95% CI: -10.50, -2.55) CFU/m3. Meanwhile, the indoor bacterial concentration of LAF systems decreased by 40.05 (95% CI: -55.52, -24.58) CFU/m3 compared to that of conventional HVAC systems. The HVAC systems in hospitals can effectively remove bioaerosols. Further, the use of HEPA filters is an effective option for areas that are under-ventilated and require additional protection. However, other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi. Although our study analysed the overall trend of indoor bioaerosols, the conclusions cannot be extrapolated to rare, hard-to-culture, and highly pathogenic species, as well as species complexes. These species require specific culture conditions or different sampling requirements. Investigating the effects of HVAC systems on these species via conventional culture counting methods is challenging and further analysis that includes combining molecular identification methods is necessary. Our study was the first meta-analysis to evaluate the effect of HVAC systems on indoor bioaerosols through microbial incubation count. Our study demonstrated that HVAC systems could effectively reduce overall bioaerosol concentrations to maintain better indoor air quality. Moreover, our study provided further evidence that other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi. Our research showed that HEPA filters are more effective at removing bioaerosols in HVAC systems than the current LAF system. Therefore, instead of opting for the more costly LAF system, a filter with a higher filtration rate would be a better choice for indoor environments that require higher air quality; this is valuable for operating room construction and maintenance budget allocation.

Effects of operating room layout and ventilation system on ultrafine particle transport and deposition

The main role of Heat Ventilation and Air Conditioning (HVAC) systems in Operating Rooms (ORs) is to ensure the desired thermo-hygrometric conditions and indoor air quality, minimizing the risk of air contamination. The main sources of contamination inside ORs, during surgical operations, are Colony-Forming Units (CFUs), fine particles and ultrafine particles (UFPs), which could cause surgical site infections or health issues for the medical staff. The present work aims at increasing the scientific knowledge concerning numerical modelling of the UFP transport and deposition in ORs, analysing the effectiveness of three different ventilation systems. A numerical methodology, validated in previous works, has been used to study UFP transport and deposition inside three actual ORs, two of them equipped with a Laminar AirFlow (LAF) system and one with a Turbulent Mixing Airflow (TMA) system. Both the LAF and the TMA systems effectively evacuate the UFPs, ensuring a particle deposition rate significantly lower than the evacuation rate. The installation of extraction grilles near the surgical table allows obtaining an improvement of UFP evacuation. Due to the not perfect symmetry of OR layouts and surgical wound position, a preferred way for UFP transport can be observed. The instrument table position should be chosen consequently, to reduce UFP, CFU and contaminant deposition. The UFP concentrations at surgical staff head height cannot be neglected for health-related risks.

Experimental and numerical study on the thermal plumes of a standing and lying human in an operating room

This paper presents a study regarding the thermal plumes generated by two thermal manikins in different positions, both numerically and experimentally. The numerical model represents an operating room with two surgeons, a patient, and a ventilation system with a unidirectional air flow diffuser, also called a laminar air flow diffuser, and outlets placed in the corners. The experimental study was made in a climatic chamber, similar with the numerical model, using particle image velocimetry and infrared thermography measurements. The thermal plumes of the two manikins were obtained by numerical and experimental studies. Another purpose of the study was to see how these thermal plumes will interfere with a low velocity ventilation system, like a unidirectional air flow system. The studies showed thermal plume velocities up to 0.35-0.4 m/s for a human subject that is standing and up to 0.2 m/s for a human subject that is lying on a bed. Analyzing the interaction of the thermal plumes with a diffuser that has low airflow velocities, like a laminar air flow system, one can observe that velocities ≥0.2 m/s will have difficulties in overcoming the thermal plumes generated by human subjects that have a sedentary to moderate activity.

Experimental and simulated evaluations of airborne contaminant exposure in a room with a modified localized laminar airflow system.

The traditional mixing ventilation is not an energy effective approach to remove indoor air pollutants, maintain breath zone air quality, and control the airborne transmission. This study investigated the potential of a localized laminar airflow ventilation system to alleviate human exposure to pollutants. Breathing thermal manikins with sitting posture and supine posture were used to simulate the human. N2O was used as the tracer gas to simulate the indoor pollutant emission. The contaminant exposure index (εexp) and intake fraction index (IF) were used to assess the risk of human pollutant exposure for various supply air velocities given different emission source positions. Enhanced pollutant removal efficiency (Eff) (from the result) showed the qualification and desirability of the localized laminar airflow ventilation system in improving the breath zone air quality. The results showed that the CFD results could fit well with the experimental data and found out the interaction between thermal plume and supply air. The results also indicated a low εexp and IF, with over 90%, all of which were highly correlated with the supply velocity. Human's different breathing methods have little influence on the pollutant exposure so as to the location of the pollution source. This study found that localized laminar airflow ventilation system could efficiently provide fresh air to the breathing zone without sacrificing the thermal environment around human. It can be used for small region air quality control such as that in the bedroom and living room where desired air quality is favored.

Suitability evaluation on laminar airflow and mixing airflow distribution strategies in operating rooms: A case study at St. Olavs Hospital

Operating room (OR) is an indispensable department in a hospital, while its ventilation system is an important engineering solution to ensure safety for surgical procedures. Suitable ventilation system in the OR should be defined as using the minimum energy consumption and lifecycle cost to meet both the requirements of clean air for safe surgeries and comfort for occupants. Therefore, this study aims to develop a flexible evaluation framework on the suitability evaluation for ventilation system performance in ORs from a holistic view instead of one aspect only. To achieve the objective, we adopted analytic hierarchy process (AHP) and fuzzy comprehensive evaluation (FCE) methods and conducted suitability evaluation for two ORs with laminar airflow (LAF) and mixing ventilation (MV) system in St. Olavs Hospital, Norway. The evaluation includes seven indexes under three main aspects: ventilation effectiveness, energy consumption and users’ satisfaction. The comprehensive evaluation results are obtained through site measurements during mock surgeries, data collection and calculation as well as the questionnaire survey. Due to the unsatisfactory performance in energy consumption and thermal comfort indexes, the evaluation result of the suitability performance of the case OR with MV system was “unsuitable” while the one with LAF system was “suitable”, which reflects the situation that the energy consumption and thermal environment are sacrificed, although a clean and safe operation environment is guaranteed. The evaluation can provide basis for the commissioning of the ventilation system in the ORs of St. Olavs Hospital and provoke thinking of the ventilation system design and operation in the future.

Does the Laminar Airflow System Affect the Development of Perioperative Hypothermia? A Randomized Clinical Trial.

We aimed to compare tympanic membrane temperature changes and the incidence of inadvertent perioperative hypothermia (IPH) in patients undergoing laparoscopic cholecystectomy under general anesthesia in laminar airflow systems (LAS-OR) and conventional turbulent airflow systems (CAS-OR). Different heating, ventilation, and air-conditioning (HVAC) systems are used in the operating room (OR), such as LAS and CAS. Laminar airflow is directed directly to the patient in LAS-OR. Does laminar airflow in ORs cause faster heat loss by convection? This is a prospective, randomized study. We divided 200 patients with simple randomization (1:1), as group LAS and group CAS, and took the patients into the LAS-OR or CAS-OR for the operation. Clinical trial number: IRCT20180324039145N3. The tympanic membrane temperatures of patients were measured (°C) before anesthesia induction (T0) and then every 15 min during surgery (Tn). Changes (Δn) between T0 and Tn were measured. In the first 30 min, there was a temperature decrease of approximately 0.8 °C (1.44 °F) in both groups. Temperature decreases at 45 min were higher in group LAS than in group CAS but not statistically significant, Δ45, respectively, 0.89 (95% confidence interval [CI] [0.77, 1.02]) versus 0.77 (95% CI [0.69, 0.84]; p = .09). IPH occurred in a total of 60.9% (112 of 184) of patients in the entire surgical evaluation period in group LAS and group CAS (58.9% vs. 62.8%, p = . 59). IPH is seen frequently in both HVAC systems. Clinically, the advantage of HVAC systems relative to each other has not been demonstrated during laparoscopic cholecystectomy.

Development of a Laminar Air Flow System for Preventing Surgical Equipment Table Infections

Nowadays, the infections cause the higher patient mortality and longer time in hospitals and clinical treatment units. It requires the good quality of healthcare services. This paper presents the research in an attempt to realize a mobile laminar airflow system for preventing the contamination of airborne pathogens by protecting the surgical site area as well as the instrument table as low-cost as possible. The portable laminar airflow system and centrifugal fan are modeled by using computer-aided design (CAD) software. This system concludes a blower, UVC lamp, standard filter, high-efficiency particulate air (HEPA) filter, and instrument table. Then, the proposed device was verified through numerical simulations. Computational Fluid Dynamics (CFD) was performed to optimize the system design by examining and evaluating the results, as well as computing the aerodynamic characteristics for the system's centrifugal blower and taking fan pressure variation into account while adjusting inlet flow. As a result, sterile conditions may be created instantaneously and anyplace using this proposed laminar airflow system. The innovative layered airflow sterilizer may achieve a local Biosafety Level II in a specific area, such as an isolation room, patient bedroom, or operating room. After modeling the system, the finer mesh of centrifugal fan was carried out to ensure the accuracy of numerical simulation. There are four domains discretized in a centrifugal fan such as impeller fluid domain, volute fluid domain, inlet, and outlet fluid domain. The inlet mass flow rate strongly affects the performance of the centrifugal fan. The numerical results show that the total pressure maintained inside the blower increase as the flow rate gets larger. The results of this study provide an essential basis for optimizing system design in future investigations.

Air contamination inside an actual operating room due to ultrafine particles: An experimental-numerical thermo-fluid dynamic study

Hospital Operating Rooms (ORs) are working spaces which demand an utmost clean air environment for enhancing both the safety and the comfort conditions of medical staff and patients, in order to reduce the risk of post-operative complications. In this context, an integrated experimental-numerical thermo-fluid dynamic study has been carried out in the present work, to investigate air contamination due to UltraFine Particles (UFPs) inside an actual, but unoccupied, OR, equipped with a laminar air flow system, located near Milan in Northern Italy. The UFPs considered in the present study are geometrically representative of surgical smoke and SARS-CoV, SARS-CoV-2 (COVID-19) virus particles. The flow and thermal fields in the OR have been calculated by using the Realizable k-ε turbulence model. A transient passive scalar species transport equation, based on the drift flux model, has been implemented along with the particle deposition boundary conditions at the OR walls, to analyze the UFPs concentration within the OR. The numerical model has been used, after validation against experimental data, to reproduce the quantities of interest in the OR. Moreover, type A and type B uncertainties have been associated to the experimental measurements. The velocity and temperature fields in the OR, obtained from both the numerical and experimental analysis, are compliant to the technical standards. A good agreement is observed between experimental and numerical results, in terms of velocity, temperature and UFPs concentration. A time of 19 min to completely evacuate UFPs from the OR has been obtained from both experimental and numerical analysis, with a deviation smaller than 2% between the results.

Aerosol generation during phacoemulsification in live patient cataract surgery environment.

To investigate whether phacoemulsification is an aerosol-generating procedure in a live patient environment. New Hayesbank Ophthalmology Services, Kent, United Kingdom. In vivo experimental human eyes study. Aerosol particle counts sized 0.3 μm or lesser, more than 0.3 to 0.5 μm or lesser, more than 0.5 to 1 μm or lesser, more than 1 to 2.5 μm or lesser, more than 2.5 to 5 μm or lesser, and more than 5 to 10 μm or lesser were measured during elective phacoemulsification surgery of 25 eyes. The baseline particle count in the operating theater was measured on 2 separate days to assess for fluctuation. Then, 5 readings each during prephacoemulsification and phacoemulsification of all eyes were measured. The difference in aerosol generation during prephacoemulsification and phacoemulsification was also measured with the use of the mobile laminar air flow (LAF) machine. Finally, aerosol generation during phacoemulsification was measured using 2% hydroxypropyl methylcellulose (HPMC). There was no statistically significant difference in measurement of aerosol between the baseline measurements on both days and between each patient's prephacoemulsification and phacoemulsification stages of surgery. The LAF system showed statistically significant reduction in particles size of 0.3 μm or lesser, more than 0.3 to 0.5 μm or lesser, more than 0.5 to 1 μm or lesser, more than 1 to 2.5 μm or lesser, more than 2.5 to 5 μm or lesser, and more than 5 to 10 μm during phacoemulsification compared with that during prephacoemulsification (P value .00 for all particle sizes, t test). The use of 2% HPMC did not show any statistically significant reduction in particle measurements. Aerosol particles sized less than 10 μm are not produced during phacoemulsification of human crystalline lens in a live patient setting. The use of a mobile LAF machine significantly reduced the number of particles sized 10 μm or lesser within the surgical field.

Laminar air flow reduces particle load in TKA\u2014even outside the LAF panel: a prospective, randomized cohort study

PurposeReleased particles are a major risk of airborne contamination during surgery. The present prospective study investigated the quantitative and qualitative particle load in the operating room (OR) depending on location, time of surgery and use of laminar air flow (LAF) system.MethodsThe particle load/m3 was measured during the implantation of 12 total knee arthroplasties (6 × LAF, 6 × Non-LAF) by using the Met One HHPC 6 + device (Beckmann Coulter GmbH, Germany). Measurement was based on the absorption and scattering of (laser) light by particles and was performed at three different time-points [empty OR, setting up, ongoing operation) at 3 fixed measurement points [OR table (central LAF area), anaesthesia tower (marginal LAF area), surgical image amplifier (outside LAF area)].ResultsIndependent of time and location, all measurements showed a significantly higher particle load in the Non-LAF group (p < 0.01). With ongoing surgical procedure both groups showed increasing particle load. While there was a major increase of fine particles (size < 1 µm) with advancing activity in the LAF group, the Non-LAF group showed higher particle gain with increasing particle size. The lowest particle load in the LAF group was measured at the operating column, increasing with greater distance from the operating table. The Non-LAF group presented a significantly higher particle load than the LAF group at all locations.ConclusionThe use of a LAF system significantly reduces the particle load and therefore potential bacterial contamination regardless of the time or place of measurement and therefore seems to be a useful tool for infection prevention. As LAF leads to a significant decrease of respirable particles, it appears to be a protective factor for the health of the surgical team regardless of its use in infection prevention.Level of evidenceI.

Experimental measurements of surgical microenvironments in two operating rooms with laminar airflow and mixing ventilation systems

At present, laminar airflow (LAF) systems and mixing ventilation (MV) systems are two commonly used ventilation solutions for operating rooms (ORs) to ensure the required indoor air quality. However, recent studies have shown that there is little difference in the prevalence of surgical site infection (SSI) for the LAF systems and MV systems. The objective of this study was to compare the performance of an LAF system with an MV system in ORs at St. Olavs hospital, Norway. In this study, all the experimental measurements were conducted in real ORs with LAF and MV systems. This study found that the air velocity above the surgical incision is approximately two times higher in the OR with LAF than that in the OR with MV. The use of surgical lamps and different airflow patterns may contribute to the different surgical microenvironment of ORs with LAF and MV.

Evaluation of laminar airflow heating, ventilation, and air conditioning system for particle dispersion control in operating room including staffs: A non-Boussinesq Lagrangian study

Impacts of the laminar airflow ventilation system design factors on contaminant removal and thermal comfort condition in an operating room have been investigated by means of Lagrangian-based particle transport using the non-Boussinesq modeling of the buoyancy effects. An operating room including staffs and a patient with realistic human geometries and two surgery lights are included in simulations. The laminar airflow system is placed on the ceiling with a surrounding fixed-height partial wall and the air barrier supply grills. Effects of density change in mixed convection flow regime are included by the non-Boussinesq modeling of the exact air density variation. The predicted mean vote, the age of air, the colony-forming units per cubic meter, the average temperature, the average velocity, the relative humidity, the density distribution, and the positions of particles are calculated to assess the indoor air ventilation quality. A total of 27 simulation cases have been considered to determine the impact of three main design factors including the laminar airflow system area, the supply air, and the air barrier velocities on the performance of the system. It is concluded that for the curtain velocity of 2 m/s, the thermal comfort reduces with increasing the laminar airflow velocity, but for the third staff, the results show that for small laminar airflow areas, the speed of the inlet port should be reduced and for the larger sizes, the inverse of this trend is recommended. Moreover, for all cases the humidity varies within the range of 55%–56%, which agrees well with the suggested standard humidity range between 50% and 60%. It is concluded that the cases of the laminar airflow velocity equal to 0.3 and 0.5 at the curtain velocity of 1 m/s are generally more appropriate than other cases due to less accommodation of particles near the entire body of the patient.

Impact of air-conditioner outlet layout on the upward airflow induced by forced air warming in operating rooms

BackgroundPreviously, we found that an upward air current in the head area, induced by forced air warming (FAW), was completely counteracted by downward laminar airflow. However, this study did not include any consideration of the air-conditioner outlet layout (ACOL); hence, its impact remains unclear. MethodsThis study was performed in 2 operating rooms (ORs)—ISO classes 5 and 6, which are denoted as OR-5 and OR-6, respectively. Both ORs have distinct ACOLs. The cleanliness, or the number or ratio of shifting artificial particles was evaluated. ResultsDuring the first 5 minutes after particles generation, significantly more particles shifted into the surgical field in OR-5 when compared to OR-6 (13,587 [4,341-15,913] and 106 [41-338] particles/cubic foot, P < .0001). Notably, FAW did not increase the number of shifting particles in OR-6. The laminar airflow system fully counteracted the upward airflow caused by FAW in OR-6, where the ACOL covered the operating bed. However, this did not occur in OR-5, where the ACOL did not fully cover the operating bed. ConclusionsRegardless of cleanliness ability of OR, an ACOL that fully covers the operating bed can prevent upward airflow in the head area and reduce the number of artificial particles shifting into the surgical field, which are typically caused by FAW.

An experimental and numerical study of air flow pattern and temperature distribution of angular air distribution system in hospital operation theatre

It is necessary to characterize the air flow pattern and temperature distribution in Operation Theatre (OT) to optimize the indoor air quality to enhance the high performance of hospital. Mostly Laminar air flow system is used in OT, which covered the surgical zone. The temperature draft observed between surgical and nonsurgical area which result in uncomfortable environment to patient and surgeon. To overcome such problem Angular Air Distribution (AAD) system is designed which covered the both area of OT. The performance of AAD system with varying inlet diffuser angle at constant inlet velocity on Scale model of OT is investigated with the help of CFD software and compared with experimental setup. Detail experimental investigation is done on a scale model of OT with the help of a smoke test and camera target method (CTM). Both numerical and experimental results showed a similar pattern of air and temperature distribution for the various design configurations.

Conflicting effects of a portable ultra-clean airflow unit on the sterility of operating rooms: A numerical investigation

The onset of post-operatory surgical-site infections is significantly correlated with the concentration of viable airborne bacteria that are shed from the surgical team or entering the operating room during door openings and are deposited directly on the patient's wound or on surgical instruments.The ultra-clean vertical laminar airflow ventilation system is often used to protect the main surgical area of operating rooms. The clean zone provided by the laminar airflow system is crowded with staff and furniture. As a result, some surgical instruments might remain outside the protected area. We use a numerical simulation to investigate the capability of a portable ultra-clean airflow unit to reduce the contamination of the principal instrumentation table by airborne bacteria, during a sham operation. The numerical model is thoroughly validated against the experimental data available for a test room. The portable air-cleaning device maintains sterile conditions on the principal instrumentation table over a range of flow rates of the general ventilation, although it induces higher levels of bacterial contamination in other zones of the room at the same time.