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Surgical sterility at both of the University of Liverpool’s animal hospitals is
assured by Astell equipment
The partnership between horse and rider is unique, whether it’s for leisure riding or serious sports, so when that relationship is threatened by illness or injury, horse owners want the best possible care for their animals. Add to this the massive financial investment in buying and training a top racing, show jumping or eventing horse, and you begin to see why there is a need for the Phillip Leverhulme Equine Hospital, teaching hospital for faculty of veterinary science, Liverpool University. Built at a cost of £1.4 million, the hospital, which was named for Philip Lever, 3rd Viscount Leverhulme, of the Lever Brothers family, can trace its foundations back over a century to the days when the busy port city depended on heavy horses to drive its docks and associated industry. It now treats over 2,000 equine patients each year specialising in gastroenterology, oncology, ophthalmology, orthopaedics, respiratory problems and teaching veterinary students equine medicine.
As a surgical hospital, the standards of sterility are as high as in any hospital for humans. Instruments and dressings used in operations are all sterilised, as are contaminated surgical wastes prior to disposal. Autoclaving is the proven method so, when they needed a new autoclave, they bought an Astell 216 litre capacity Logicolor Square Section Sterilizer.
Sterility means the statistically complete destruction of all micro-organisms including the most resistant bacteria and spores. This is a condition that is difficult to achieve and harder to prove, but Astell’s sterilizers are designed to do just that. To achieve a temperature of 121°C or more, steam has to be pressurised to at least 1barg, and that means that the autoclave which contains it is classified as a pressure vessel. Astell’s pressure vessels are all constructed in 316 stainless steel and are all fully compliant with PD5500/PED/97/23EC.
Operator safety is paramount in autoclaves and HSE PM73 requires that the door is interlocked. The Square Section Sterilizer has an interlocked sliding door that inhibits the sterilisation cycle until the door is closed and locked, preventing the autoclave being opened if the internal temperature or pressure is above a preset value. Further, the door is thermally insulated to prevent the surface temperature presenting a hazard to operators and the sterilising cycle cannot start until the door is closed and locked.
The water-cooled jacket, supplied as standard, allows mains water to be circulated around the outside of the stainless steel chamber to give a rapid decrease in temperature when the sterilisation cycle is complete. This means a substantial reduction in cycle time, and is why a single sterilizer can meet all the Equine Hospital’s needs.
When an autoclave is first loaded, it is full of air that normally has to be displaced by the steam. Astell include a vacuum system to evacuate the vessel at the start of the cycle to remove any air without losing expensive steam. As the vessel cools down at the end of the cycle any steam remaining inside the chamber condenses, which means that the sterilised load could be left wet. This can lead to recontamination, and is a particular problem with dressings. However, Astell autoclaves can be fitted with an optional heated jacket which efficiently reduces condensation within the vessel, and, in conjunction with the vacuum system, ensures that absorbent loads such as fabrics and wrapped instruments are virtually dry at the end of the cycle.
With an eye to sustainability, water conservation is becoming more and more important. A thermostat allows mains water to be added to the internal tank only if the water temperature rises above a set point. This minimises the amount of water going down the drain and greatly reduces the water consumption by comparison with continuous feed autoclaves. Just in case anything goes wrong, the system pumps are protected from running dry by a float switch mounted in the reservoir. This overrides the water conservation system and feeds mains water to the tank regardless of the temperature.
It is absolutely essential that sterilisation temperature is reached in all parts of the autoclave, and this is controlled by Astell’s new LogiColor control system. Based on an industrial PLC controller with analogue and digital input/output modules, this state of the art controller distils Astell’s 80 years of experience in a user friendly system that meets the expectations of even the most demanding of Sterile Services Units.
The operator interface has a large 5.7” Touch Screen display which gives an easy to read stage by stage report on cycle time, temperature and pressure.
The controller has multiple sterilisation programmes that are factory set before delivery, but can be easily changed by the operator using the multiple access level, PIN protected touch screen. This allows the operator to set up pre-programmed cycles for example, 121°C for 15 minutes for wrapped instruments, 134°C - 121°C for 15 minutes for unwrapped instruments and 134°C for 3 minutes for Bowie Dick testing and so on. Setting the programmes is interactive using simple question and answer functionality. Among the user selectable options are delayed start, allowing sterilisation to take place overnight; sterilisation time and temperature; Holdwarm capability to maintain the autoclave at a pre-set temperature after sterilisation until required and the cooling lock release temperature.
Software is written in Automation Basic for maximum clarity and is split into well-defined blocks, each of which performs a specific function. The program is stored on a Flash Card and the controller has a battery backed 64MB memory. In addition to the optional Integral Data Printer the RS232 interface allows connection to a wide range of peripheral devices such as printers, data loggers and building management systems so that the temperature right through the sterilisation cycle and this can be recorded in accordance with Good Laboratory Practice.
Although the Equine Hospital has a high profile it’s the University of Liverpool’s new £9.6million Small Animal Teaching Hospital that is currently getting more attention. Opened in April 2007, it is the most modern and well-equipped hospital for small animals in the UK. The hospital, also part of the Veterinary faculty teaching small animal studies, covers 2500m2 and has space for 72 in-patients at any one time. With exemplary foresight, the designers have provided separate waiting areas for cats and dogs.
The new facility has a range of state of the art diagnostics such as CT and MRI scanning and is equipped with a Varian Clinac 2100 linear accelerator making it the only veterinary radiotherapy facility north of Cambridge. In terms of surgical treatment, the new hospital has an extremely modern operating suite with four operating theatres supported by an anaesthetic induction suite and an intensive care unit. All the theatres are designed with positive pressure ventilation with filtered air to ensure extremely high levels of asepsis. This is a major factor in prevention of infection, particularly for more complex operations such as joint replacements. Sterilisation of instruments, dressings and waste materials is provided by a 490 litre Astell Square Section autoclave, a larger unit that has a similar specification to its smaller stable-mate.
So surgical sterility at both of the University of Liverpool’s animal hospitals is assured by equipment that has been developed over half a century. But these days equipment not only has to work, it has to be seen to work so, as part of the commissioning programme, Astell will validate the autoclaves, by multi-point temperature mapping, to establish suitable loading configurations and cycle parameters which will assure repeatability of performance. Astell’s UKAS accreditation means that the validation documentation is fully traceable and is a guarantee of quality. And that’s straight from the horse’s mouth! |
