scholarly journals An evaluation of a partial-walled laminar-flow operating room

1974 ◽  
Vol 73 (1) ◽  
pp. 61-74 ◽  
Author(s):  
W. Whyte ◽  
B. H. Shaw ◽  
M. A. R. Freeman
Keyword(s):  
Laminar Flow ◽  
Operating Room ◽  
Bacterial Count ◽  
Air Velocity ◽  
Wound Site ◽  
Freedom Of Movement ◽  
Sound Levels ◽  
Airborne Contamination ◽  
Clean Area ◽  
Average Figure

SUMMARYThis paper contains an assessment of the physical performance of a permanently installed down-flow laminar-flow operating room at the London Hospital. This system employs partial walls extending 0.76 m (2.5 ft.) from the ceiling, from which the air is allowed to issue freely downwards at an initial velocity of about 0.4 m./sec. (80 ft./min.).The usefulness of the partial wall, as compared with a free issuing system, was demonstrated and a comparison made with a fully walled system. It was shown that a fully walled system would be more efficient than a partial-walled system as there was a loss in air velocity of about 20–25% with the partial wall due to the nonconstrained flow of air. This loss would be reflected in an increase in airborne bacterial count and would mean that an increase of 20–25% in the air volume would be required to obtain the same conditions as with the full-walled system. Entrainment of contaminated air was demonstrated but it was concluded that this would be of little consequence in the centre of the clean area, i.e. at the wound site. Sterile instruments, etc., however, on the outside of the clean area, would be more liable to airborne contamination.Bacterial and dust airborne counts taken during total hip operations gave a very low average figure (0.3 bacteria/ft.3 or 10.5/m.3) from which we conclude that the system was about 30 times cleaner in terms of airborne bacteria than a well ventilated conventional operating-room. We concluded that although the partial-walled system was slightly less efficacious than a normal full-walled system, the freedom of movement and of communication for the operating team could in some circumstances outweigh this disadvantage.Sound levels were such that normal conversation was possible with little or no awareness of background noise.

scholarly journals Airborne contamination in an operating suite: report of a five-year survey

1984 ◽  
Vol 93 (3) ◽  
pp. 567-573 ◽  
Author(s):  
Asakatsu Suzuki ◽  
Yoshimichi Namba ◽  
Masaji Matsuura ◽  
Akiko Horisawa
Keyword(s):  
Bacterial Species ◽  
Bacterial Count ◽  
Operating Rooms ◽  
Particle Count ◽  
Airborne Contamination ◽  
Significant Difference ◽  
Clean Area ◽  
The Mean ◽  
Operating Suite

SummaryAirborne contamination in an operating suite was studied with a slit sampler, settle plates and a light-scattering particle counter. In conventional operating rooms there was a significant difference between the empty rooms and rooms in use; the mean total bacterial count by a slit sampler changed from 1·1 in empty to 42·5 c.f.u./m3 in use (39 times increase), the settle plates count changed from 1·5 to 17·4 c.f.u./m2/min (12 times increase), and the mean total particle count changed from 56·9 to 546·7/1 (10 times increase) respectively. The increase was caused mainly by persons present in the room.Another difference was found between zones in the operating suite; the bacterial count in the clean area doubled in the semi-clean area and further doubled in the dirty area in slit sampler count as well as settle plates count, and particle count in the clean area increased by 14 times in the semi-clean and dirty areas. This difference resulted from the different quality of the ventilating system.Air cleanliness of operating rooms in use by persons present in the room dropped to a level between the clean and the semi-clean area in spite of the high quality of the ventilating system.Bacterial species identified were mostly coagulase negative staphylococci and micrococci.Our study indicates that reduction of airborne contamination in an operating suite is accomplished by the combination of an efficient ventilating system and the restriction of the number of persons present in the room.

Laminar flow for a cardiac operating room

AORN Journal ◽  
1972 ◽  
Vol 15 (5) ◽  
pp. 61-65
Author(s):  
Richard E. Clark
Keyword(s):  
Laminar Flow ◽  
Operating Room

Design of a Microfin Array Heat Sink Using Flow-Induced Vibration to Enhance the Heat Transfer Rate in the Laminar Flow Regime

2001 ◽  
Author(s):  
Jeung Sang Go ◽  
Geunbae Lim ◽  
Hayong Yun ◽  
Sung Jin Kim ◽  
Inseob Song
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Heat Transfer Enhancement ◽  
Flow Regime ◽  
Heat Transfer Rate ◽  
Heat Sink ◽  
Transfer Rate ◽  
Transfer Enhancement ◽  
Air Velocity ◽  
Flow Induced Vibration

Abstract This paper presented design guideline of the microfin array heat sink using flow-induced vibration to increase the heat transfer rate in the laminar flow regime. Effect of the flow-induced vibration of a microfin array on heat transfer enhancement was investigated experimentally by comparing the thermal resistances of the microfin array heat sink and those of a plain-wall heat sink. At the air velocities of 4.4m/s and 5.5 m/s, an increase of 5.5% and 11.5% in the heat transfer rate was obtained, respectively. The microfin flow sensor also characterized the flow-induced vibration of the microfin. It was determined that the microfin vibrates with the fundamental natural frequency regardless of the air velocity. It was also shown that the vibrating displacement of the microfin is increased with increasing air velocity and then saturated over a certain value of air velocity. Based on the numerical analysis of the temperature distribution resulted from microfin vibration and experimental results, a simple heat transfer model (heat pumping model) was proposed to understand the heat transfer mechanism of a microfin array heat sink. Under the geometric and structural constraints, the maximum heat transfer enhancement was obtained at the intersection of the minimum thickness of the microfin and constraint of the bending angle.

Wound Ventilation With Ultraclean Air for Prevention of Direct Airborne Contamination During Surgery

2004 ◽  
Vol 25 (4) ◽  
pp. 297-301 ◽  
Author(s):  
Mikael Persson ◽  
Jan van der Linden
Keyword(s):  
Operating Room ◽  
Median Number ◽  
Airborne Particles ◽  
University Hospital ◽  
Surgical Wound ◽  
Wound Model ◽  
Wound Contamination ◽  
Room Ventilation ◽  
Airborne Contamination ◽  
Number Of Particles

AbstractBackground and Objective:Despite the novelties in operating room ventilation, airborne bacteria remain an important source of surgical wound contamination. An ultraclean airflow from the ceiling downward may convey airborne particles from the surgical team into the wound, thus increasing the risk of infection. Therefore, similar ventilation from the wound upward should be considered. We investigated the effect of wound ventilation on the concentration of airborne particles in a wound model during simulated surgery.Design:Randomized experimental study simulating surgery with a wound cavity model.Setting:An operating room of a university hospital ventilated with ultraclean air directed downward.Interventions:Particles 5 um and larger were counted with and without a 5-cm deep cavity and with and with-out the insufflation of ultraclean air.Results:With the surgeon standing upright, no airborne particles could be detected in the wound model. In contrast, during simulated operations, the median number of particles per 0.1 cu ft reached 18 (25th and 75th percentiles, 12 and 22.25) in the model with a cavity and 15.5 (25th and 75th percentiles, 14 and 21.5) without. With a cavity, wound ventilation markedly reduced the median number of particles to 1 (range, 0 to 1.25;P< .001).Conclusions:To protect a surgical wound against direct airborne contamination, air should be directed away from the wound rather than toward it. This study provides supportive evidence to earlier studies that operating room ventilation with ultraclean air is imperfect during surgical activity and that wound ventilation may be a simple complement. Further clinical trials are needed.

Numerical Simulation of the Tunnel Oven with Fluent Software

2011 ◽  
Vol 399-401 ◽  
pp. 1856-1861
Author(s):  
Ming Wei Wan ◽  
Suo Huai Zhang
Keyword(s):  
Numerical Simulation ◽  
Laminar Flow ◽  
Pressure Distribution ◽  
Negative Pressure ◽  
Air Velocity ◽  
Hot Air ◽  
Speed Range ◽  
Fluent Software ◽  
Air Speed

After the model of sterilization area was established, numerical simulate was completed with fluent software. Verified with certain conditions of hot air velocity, the laminar flow tunnel oven is able to meet the relevant requirements of GMP. Under different speeds of hot air, the tunnel oven vials’ relationship between temperature and time, combined with analysis of pressure distribution inside the oven. When the air speed range from 0.6m/s to 1.5m/s, the temperature of vials meet the requirements and the minimum effect of negative pressure to oven.

scholarly journals Forced-air warming: a source of airborne contamination in the operating room?

2009 ◽  
Vol 1 (1) ◽  
pp. 28 ◽  
Author(s):  
David Leaper ◽  
Mark Albrecht ◽  
Robert Gauthier
Keyword(s):  
Operating Room ◽  
Size Range ◽  
Filtration Efficiency ◽  
Microbial Colonization ◽  
Particle Size Range ◽  
Forced Air Warming ◽  
Airborne Contamination ◽  
Steep Decrease ◽  
Forced Air ◽  
Bacteria And Fungi

Forced-air-warming (FAW) is an effective and widely used means for maintaining surgical normothermia, but FAW also has the potential to generate and mobilize airborne contamination in the operating room. We measured the emission of viable and non-viable forms of airborne contamination from an arbitrary selection of FAW blowers (n=25) in the operating room. A laser particle counter measured particulate concentrations of the air near the intake filter and in the distal hose airstream. Filtration efficiency was calculated as the reduction in particulate concentration in the distal hose airstream relative to that of the intake. Microbial colonization of the FAW blower’s internal hose surfaces was assessed by culturing the microorganisms recovered through swabbing (n=17) and rinsing (n=9) techniques. Particle counting revealed that 24% of FAW blowers were emitting significant levels of internally generated airborne contamination in the 0.5 to 5.0 mm size range, evidenced by a steep decrease in FAW blower filtration efficiency for particles 0.5 to 5.0 mm in size. The particle size-range-specific reduction in efficiency could not be explained by the filtration properties of the intake filter. Instead, the reduction was found to be caused by size-range-specific particle generation within the FAW blowers. Microorganisms were detected on the internal air path surfaces of 94% of FAW blowers. The design of FAW blowers was found to be questionable for preventing the build-up of internal contamination and the emission of airborne contamination into the operating room. Although we did not evaluate the link between FAW and surgical site infection rates, a significant percentage of FAW blowers with positive microbial cultures were emitting internally generated airborne contamination within the size range of free floating bacteria and fungi (<4 mm) that could, conceivably, settle onto the surgical site.

AN EXPERIMENTAL LAMINAR-FLOW OPERATING-ROOM

The Lancet ◽  
1971 ◽  
Vol 298 (7730) ◽  
pp. 905-906 ◽  
Author(s):  
W. Whyte ◽  
B.H. Shaw ◽  
R. Barnes
Keyword(s):  
Laminar Flow ◽  
Operating Room

scholarly journals A bacteriological evaluation of laminar-flow systems for orthopaedic surgery

1973 ◽  
Vol 71 (3) ◽  
pp. 559-564 ◽  
Author(s):  
W. Whyte ◽  
B. H. Shaw ◽  
R. Barnes
Keyword(s):  
Laminar Flow ◽  
Operating Room ◽  
Orthopaedic Surgery ◽  
Flow System ◽  
Air Flow ◽  
Cross Flow ◽  
Operating Rooms ◽  
Airborne Bacteria ◽  
Flow Systems ◽  
Bacteriological Evaluation

SUMMARYAn evaluation has been undertaken of the efficiency of laminar-flow ventilation in operating-rooms in which conventional operating-room clothing was used. It has been demonstrated that velocities in the region of 0·3–0·4 m/sec. will give maximum returns for effort in both down-flow and cross-flow systems. At this velocity the laminar-flow system, in terms of airborne bacteria measured at the would site, was about 11 times more effients using horizontal air-flow and 35–90 times more efficient using vertical air-flow than a plenum-ventilated operating room.

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