Design of Hospital Isolation Rooms
毕福剑视频事件Introduction 腊肉制作方法和配方
The hospital prents a unique built environment in many ways. Large hospitals have the population and diversity of mediums sized towns. The hospital is unlike any other built environment, as the functions within have created a microbial ecosystem found nowhere el. We have all heard stories of people having left hospital in a wor state than which they entered. The health industry is facing its biggest threat yet, the prence of multi drug-resistant organisms such as MRSA, VRE (Vancomycin resistant enterococci) and multi drug resistant tuberculosis. The incread u of antibiotics coupled with a sicker than
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ever hospital population, in a clod ecosystem, is leading to rious problems within the health industry. Engineers, technicians and tradesmen are been called upon to design, install, maintain and modify highly specialid hospital facilities with very limited understanding of the true clinical requirements of the systems. Communication between
health professionals and rvices professionals has often been poor due to the lack of understanding between disciplines. All too often the health professional is unable to articulate their needs due to a fundamental lack of knowledge of what building systems are capable of achieving whilst not passing on the necessaryscientific knowledge the designer requires. This said, should the information be provided, how many engineers would know, for example, the principles of droplet nuclei formation?
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鸡冲什么生肖Good cooperation and understanding of engineering, administrative, medical and nursing needs are esntial if we are to reduce the transmission of microorganisms in health care facilities.
The Nature of Airborne Infection.
Air is only infectious if it contains particles capable of causing an infection. A concentration of infectious particles will occur if fewer particles are removed from the space than are generated. Infection relies on both the pathogenicity of an organism and the number of viable organisms able to penetrate the host defences. Organism bearing p
articles are introduced into the air from activities involving the respiratory tract, such as sneezing and coughing and from movements that shed bacteria laden particles from the skin. Disturbance of dust, which generally is organism laden, provides a condary source of airborne bacteria. Normal breathing will expel low numbers of low velocity particles, whereas coughing or sneezing will expel high numbers of high velocity particles “Experiments by Duguid in 1945 showed normal speech liberated up to 200 droplets bearing bacteria, less than 100 microns in diameter. Various coughs liberated up to 3500 bacteria and sneezing liberated between 4500 and 1 million droplets less than 10 microns in diameter. Velocities of up to 300 m/s in sneezing and coughing result in considerable reductions in particle size compared to tho liberated during speech”
Larger droplets fall rapidly to the ground where they desiccate. In this state, the organisms may survive for extended periods only to be resuspended within dust particles when the dust is disturbed.
Persistence of Organisms.
The ventilation rate of a room must be designed to prevent the build up of buoyant contaminants (infectious particles). Particles can be divided into two categories:
1、 Particles removed by ttling.
2、 Particles removed by ventilation.
Large particles can only stay suspended for short periods. The particles will ttle clo to the source. Droplet nuclei particles are
buoyant, therefore they will remain suspended for long periods unless removed by ventilation.
Transmission of infection within the hospital (Nosocomial Infection)
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钱鼓舞Microorganisms are transmitted in hospitals by veral routes, and the same microorganism may be transmitted by more than one route. There are five main routes of transmission: contact, droplet, airborne, common vehicle, and vector borne. Vehicle and v
ector borne transmission will be not be discusd, as neither plays a significant role in typical nosocomial infections.
Airborne Transmission
Airborne transmission occurs when either airborne droplet nuclei or dust particles disminate infectious agents. Air currents can widely disper such microorganisms, which a susceptible host (near or quite far from the source patient) can then inhale. Control of environmental factors (such as special air handling and ventilation) is necessary to prevent nosocomial airborne transmission of microorganisms such as measles, chicken pox and Mycobacterium tuberculosis. 纯色图片
The droplet nuclei
Droplets prents large surface areas and therefore evaporate rapidly in the air. The rate of evaporation is determined by the droplet size. The rate at which evaporation occurs depends on the difference of the pressure of the water vapour in the air and that at the su
rface of the droplet. When the relative humidity is low, evaporation of the droplet occurs rapidly. As the droplet
evaporates the concentration of dissolved substances increas. The droplet decreas in size until the concentration of dissolved substances is such that the vapour pressure the droplet exerts is equal to the atmospheric pressure. If the saturationpressure of the droplet at equilibrium is greater than the saturation pressure of the atmospheric water vapour, with the evaporation of the remaining water, the contents of the droplet will crystallize. The residue of the droplet after evaporation, which contains any organism originally prent, is called droplet nuclei. As the water evaporates, the weight of the droplet decreas, and therefore the droplet ttling rate decreas.
Droplet nuclei ttle so slowly, that in occupied spaces they remain airborne and circulate on air currents within the space. Circulation will continue until the droplet nuclei are removed by the ventilation system.
