The washer disinfector cycle time dilemma
The NHS is under extreme pressure. Years of austerity, during which the service has consistently been underfunded, with cuts to frontline services, social care and mental health, have been followed by the unprecedented demands caused by the Covid pandemic. Add to this equation the ageing demographic and the growth in patients with chronic and multiple conditions, and you have a perfect storm.
These pressures are being felt at all levels, from recruitment, staffing levels and morale, to the procurement of new equipment and the maintenance and operation of systems that have often exceeded their recommended operating life.
In the area of endoscope reprocessing, for example, there is a growing trend to reduce the cycle times of washer disinfectors as a means of increasing the availability of instruments for hard-pressed hospital departments.
Reducing cycle times
Reducing the cycle times for washer disinfectors can be achieved in a number of ways, of which perhaps the simplest is to increase the temperature of the feedwater. This minimises the need for the washer disinfector to heat what is normally a cold feed to the correct temperature before effective endoscope cleaning can take place.
In principle, this can be an effective solution to reduce cycle times. It does, however, require that careful consideration be given to the nature of the water purification systems and distribution system. For example, heating elements can easily be built into the water purification system, but this carries an elevated risk of bacteria growing within the system unless suitable remediation measures are included; these might include heat sanitisation, UV, ozone or chemical dosing equipment.
Even with this equipment in place it is arguably even more important to maintain a robust water quality monitoring regime, to ensure that the requirements of HTM 01-01 and HTM 01-06 are met. In particular, the need to reduce protein contamination after processing to less than 5μg BSA equivalent per instrument side, with the final rinse water containing less than 10 cfu/100ml.
The importance of peak flow
A factor that is often overlooked is the importance of peak flow. This is especially critical in decontamination and sterile services departments where multiple washer disinfectors are in use, often simultaneously. Although the peak flow demand for each washer disinfector may only last for a short period it is critical that the total peak flow for all units is accurately calculated to eliminate the risk of failed rinse cycles due to a fall in supply pressure. The water purification and distribution system must then be designed accordingly.
Changes in demand
Finally, bear in mind that increasing the demand on the water purification system, either by reducing cycle rates or increasing the number of washer disinfectors that need to be supplied, will have an impact on the operation of the water purification system. This may include, for example, greater demand for service and maintenance, faster depletion of salts in water softeners or, with systems that normally have a two or more reverse osmosis membrane to provide 100% redundancy, periods when all membranes may be operating at full capacity.
