SURGICAL SITE INFECTIONS
for instance, will be required to ensure the separation of areas within the suite by maintaining a specific direction of air flow between rooms, even when doors are opened.
They will also maintain the selected operating department’s environmental conditions regardless of changes in outside air conditions or activities within the space. In addition, ultra-clean ventilation systems (which are designed to provide a zone around the patient that is effectively free of bacteria- carrying airborne particles while the operation is in progress) have been shown to significantly reduce surgical site infection in patients undergoing large joint replacement surgery. Their use for other forms of surgery may well be indicated.9
Since this was written in
2007 there has been increasing consideration that Laminar airflow (or ultra clean ventilation) systems should be questioned and further research undertaken to establish their benefit.10 HBN 26 the Health Building Note11 which guides all public hospital new buildings identifies that ventilation has four main functions: n Dilution of bacterial contamination n Control of air movement within the theatre suite such that the transfer of airborne bacteria from less clean
to cleaner areas is minimised
n Control of space temperature and humidity
n To assist in the removal and dilution of anaesthetic gases.
The main sources of contamination in the surgical environment are the patient, the surgical team and the environment itself. Ventilation serves to dissipate and control the pollutants which include skin squames shed by the staff and also the patient, although the latter is minimal, and to dilute and exclude anaesthetic gases. If the anaesthesia gases are not removed effectively, the productivity and quality of work of the team will suffer. Surgical smoke is also considered
hazardous, which is largely ignored by the surgical team, but has been shown to be the source of carcinogenic particles. If these are not removed at source via specialised suction and filtration, will be an airborne contaminant which relies on the ventilation to remove it.12 The number of pollutants in the operating theatre air will vary according to the ventilation system in place, the type of surgery being undertaken and the number of people in the team. Those people often move in and out of
the theatre, which is known as traffic, and as traffic increases with subsequent opening and closing of doors, the ventilation has to work harder to ensure appropriate circulation is maintained. The number of particles released by people in theatre increases with movement and multiplies by the number of people present.13
maximum number identified but there should be sufficient staff to support the patient and the team effectively, with minimising staff numbers a core emphasis within safe parameters. Few countries have set bacterial
thresholds for conventionally ventilated theatres although most regulate the air exchange at 20 air changes per hour (ACH) and within that a limit of 35 cfus/ m3
activity 180cfus/m3
in an empty theatre and in .
Laminar airflows obviously have
much greater capacity to filter the air via the HEPA filter systems and the greater air exchange rates 300 – 500 ACH.14
It is essential that there is
awareness and discipline amongst the theatre team members, to reduce coming and going. Not only will this reduce shedding of skin scales, but will also fundamentally assist the effectiveness of the ventilation, thus reducing airborne contaminants.
OPERATING THEATRE l JULY 2018 l 15
There is no
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