In an operating theatre M&E installation, cost, energy-efficiency and comfort are not the only design considerations.
Operating theatres vary widely, from legacy general surgery theatres to specialist ultra clean theatres with stringent air quality standards, so the only approach to take is one tailored to individual requirements.
In an existing hospital, while there is likely to be new plant installed for each operating theatre, it is also essential to interface the new M&E installation with existing services without operational interruption elsewhere in the hospital.
The building services team must work collaboratively with the hospital’s maintenance team from the earliest stages of the project to ensure standardisation and compatibility of materials.
This not only means new lighting systems can interface with the existing building management systems, for example, but also ensures the maintenance team is familiar with the technologies being used.
Space in the operating theatre is at a premium and minimising the programme is vital.
As a result, the installation needs to be designed to reduce the amount of labour required by decluttering the complexity of the cabling, pipework and ductwork. This streamlined approach also enables easier maintenance.
The installation should also be designed with futureproofing in mind, with additional capacity in the cable management, for example.
There are numerous Heath Technical Memorandum governing operating theatre air quality requirements, but the disparate variety of operating theatres across legacy hospital estates means some are more easily upgraded than others.
“Pressure regimes exist to manage the differential air pressure between the operating theatre, the anaesthesia room and the patient preparation area”
Already such projects are under significant time constraints, as it is logistically difficult for any hospital to have just one operating theatre out of action even for the shortest of refurbishment programmes.
The building services design must take account of ease and speed of installation, along with the type or theatre, its location within the building, the design layout and how that will affect the viability of pressure regimes.
Pressure regimes exist to manage the differential air pressure between the operating theatre, the anaesthesia room and the patient preparation area.
The premise is that the air movement system will create a positive pressure by feeding more clean air into the space than it is extracting, contributing to infection control.
To comply with HTM0301 air quality requirements, ventilation systems for standard procedure operating theatres must deliver a minimum of 25 air changes per hour.
However, the volume of clean air circulated by the system must be calculated on the basis of the size of the space. It must also be distributed in a linear circulation from the grille to the floor and balance air extract with clean air to fulfil pressure regime requirements.
For ultra clean theatres, this 25 air changes per hour requirement leaps up substantially to 500 air changes per hour within a 2.7 m zone around the operating table and, here, a combination of increased air changes and HEPA filtering is required to ensure the air quality is as pure as possible.
The system should be designed to ensure colony-forming units of bacteria are eliminated from the operating site to the greatest extent possible.
The heating and ventilation system should also be designed for maximum flexibility and controllability with accessible controls to make sure temperatures can be altered to meet individual surgeon and patient needs in real time.
A final point to consider is that the surgeon’s panel must provide real-time status information about the ventilation and heating system, humidity levels, medical equipment status and so on, calling for full integration of controls with monitoring and display.
Steve Hunt is managing director at Steven Hunt Associates