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Item X-ray diagnostic equipment(EWH, 1990)X-rays are invisible. Because of their high energy and short wavelength they can penetrate almost all materials, but are absorbed to a different extent by different tissues. In the human body, absorption is high for bones, and low for muscles and other soft tissues. These differences in absorption can be shown on a photographic film as differences in density: the result is a radiograph. Thus, radiographic examination consists of irradiating a part of the patient with a uniform beam of X—rays and recording the emerging rays on a double emulsion film sandwiched between a pair of fluorescent screens. The screens convert the X-rays into light, which in turn exposes the X-ray film. The screens and the film are enclosed in a cassette for protection from daylight. After the exposure, the film must be processed, manually or automatically, in a darkroom by means of developer and fixer solutions. X-ray examinations should be ordered only by physicians or experienced clinical health workers. "Routine" examinations are seldom indicated. A few of the more common indications and examinations that can be performed with diagnostic X-ray equipment are listed below (this is not a complete list).Item X-ray diagnostic equipment(????, 1990)X-rays are invisible. Because of their high energy and short wavelength they can penetrate almost all materials, but are absorbed to a different extent by different tissues. In the human body, absorption is high for bones, and low for muscles and other soft tissues. These differences in absorption can be shown on a photographic film as differences in density: the result is a radiograph. Thus, radiographic examination consists of irradiating a part of the patient with a uniform beam of X—rays and recording the emerging rays on a double emulsion film sandwiched between a pair of fluorescent screens. The screens convert the X-rays into light, which in turn exposes the X-ray film. The screens and the film are enclosed in a cassette for protection from daylight. After the exposure, the film must be processed, manually or automatically, in a darkroom by means of developer and fixer solutions.Item Oxygen entrainment systems(WHO, 1994)This article describes the principles of oxygen entrainment systems.Item Centrifuges Basic principles(WHO, 1994)Item Anaesthetic and resuscitation equipment(WHO, 1994)The Oxford Bellows is a hand-operated bellows unit for inflating the lungs (Fig. 4.1). It consists of an inlet connection and valve, the bellows in the middle, an outlet valve with outlet connection, and tap. There is a magnet in a holder under the bellows, which is used to immobilize the disk valve when a non-return valve (such as the Ambu) is in use.Item Systems for Continuous-Flow Anesthesia(WHO, 1994)Continuous-flow anaesthetic machines (commonly known as Boyle's machines or simply gas machines) are in widespread use. They rely on a supply of compressed medical gas, either from cylinders attached directly to the machine or piped from a large bank of cylinders or liquid oxygen supply elsewhere in the hospital. The two gases most commonly used are oxygen and nitrous oxide.Item Gas cylinders and gases(WHO, 1994)It is assumed that hospital laboratories, theatres, and other departments that use gas cylinders will be using cylinders owned by the vendor. The problems of refilling will therefore not be considered. Cylinders are intrinsically simple devices (Fig. 2.17) requiring little or no maintenance. However, they are potentially highly dangerous because of the pressure of the contained gas. The pressure within a fully charged cylinder may be governed by local requirements, but can be as high as 20 MPa. For this reason, cylinders should be treated and maintained with care to avoid damage.Item Antistatic Equipment and Apparatus(WHO, 1994)This article describes the risks associated with the use of bottled gasses in the operating room.Item Testing Anesthetic Machines, Ventilators and Related Equipment(WHO, 1994)Anaesthetic machines and ventilators should be tested in the room or area where the equipment is situated, if at all possible. Service personnel must wear accepted operating-room clothing in the surgical areas. Contact the person responsible for operating-room equipment regarding the movement or servicing of any such equipment.Item Oxford miniature vaporizer (OMV)(WHO, 1994)Oxford miniature vaporizer (OMV) This is a small vaporizer (Fig. 4.7) which can be used to administer anaesthetics. It works in the same way as the larger vaporizers, but does not have a built-in temperature compensation device. However, the base is filled with antifreeze to help stabilize the internal temperature. A number of different versions are available, each of which can be fitted with different scales for use with different anaesthetic agents.Item Checking Power Supplies, Plugs, and Spares(VSO, 1995) Skeet, Muriel; Fear, DavidThis article describes how to troubleshoot and test power supplies, sockets, and plugs.Item BOTTLED MEDICAL OXYGEN AND OXYGEN CONCENTRATORS(VSO, 1995) Skeet, Muriel; Fear, DavidBottled oxygen is supplied under pressure in specially designed steel cylinders of varying sizes. British Standard oxygen bottles range in capacity from 170 litres to 6800 litres.Item Ophthalmoscopes and otoscopes(WHO, 1995)If the instrument is not in use for any length of time, remove the batteries to prevent corrosion. Removal of batteries that have corroded can be difficult. If the rheostat assembly can be removed from the handle, soaking the handle in boiling water helps to dislodge the batteries. Some handles have a hole in the bottom; in this case introduce a punch through the hole to tap the batteries out. A fter removal of the batteries, thoroughly clean the handle.Item Theatre Equipment: Operating Tables(VSO, 1995) Skeet, Muriel; Fear, DavidAn operating table has several features which allow the surgical team to position the patient as required (Figure 35). As there are many models, the following information is presented as a general guide only.Item Autoclaves: Safety and Diagrams(VSO, 1995)This article covers the different types of loads an autoclave can be designed for and how each type of autoclave is different, it provides information for testing the different parts on an autoclave, and it covers how to maintain an autoclave to ensure it is safe. It also provides detailed procedures for operating a variety of different autoclaves.Item Refrigerators: Care and Safe Use of Medical Equipment(VSO, 1995) Skeet, Muriel; Fear, DavidA refrigerator consists of a heavily insulated cabinet with an efficient door seal which prevents heat from the outside entering the cabinet. The temperature inside a refrigerator is kept low by a closed coiled circuit of copper tubing filled with a ‘refrigerant gas’. This ‘refrigerant gas’ absorbs heat which is then discharged at the back of the refrigerator as room air passes over a closed network of copper tubing. This is the condenser.Item Boiling Water Disinfectors(VSO, 1995) Fear, David; Skeet, MurielThe boiling water disinfector consists of a metal box with a closely fitting lid; in some cases a gasket is fitted between the box and the lid. The water vapour should pass without obstruction via the lid. Inside, the disinfector has a perforated tray which is positioned to allow the water to circulate. The tray may be fitted with removable handles to take it out. Some models of disinfectors are equipped with a handle-operated mechanism for lifting the tray out of the water. The disinfector stands on four small feet allowing air to circulate around it and preventing damage to the underlying surface. Heating can be provided by electricity, a paraffin stove or any other heat source. In the electric models, heat is generated by an electric heating element, either of the immersion or the panel type.Item Oxygen Concentrators: Care and Safe Use of Medical Equipment(VSO, 1995)This article describes the principles behind oxygen concentrators, some basic safety routines that should be performed, and how to safely use and maintain an oxygen concentrator.Item Flame photometers(WHO, 1995)Flame photometers are used routinely for the measurement of lithium (Li), sodium (Na), and potassium (K) in body fluids. More sophisticated instruments can also measure calcium (Ca). In flame photometry, an aqueous salt solution is dispersed in air. The salt in the dispersed droplets is transferred into a gaseous state by heating with a flame, and then quickly disintegrates into gaseous atoms. Above a critical temperature the atoms absorb energy, which excites the electrons into higher energy states. When the excited electrons return to their original state, they emit the absorbed energy as light. The wavelength of the light emitted by each metal is characteristic for that element. The intensity of the light emitted at the given wavelength is proportional to the number of excited metal atoms and can be measured with a suitable optical filter and photodetector.Item Operating Room Lamps(VSO, 1995) Skeet, Muriel; Fear, DavidA fixed theatre lamp is suspended from the ceiling of an operating theatre or treatment room, directly over the centre of the table. It can be positioned by moving the lamp head and its outreach arm (Figure 38). It has at least four units which produce a very high level of light without shadow. Usually the light is produced by high intensity tungsten halogen bulbs which are similar to the headlight bulbs of motor cars. Voltage of these bulbs varies depending upon the design but it is either 12 or 24 volts AC or 12 or 24 volts DC. This is a safety measure to prevent electric shocks. At the back of the lamp there is a polished metal reflector whi