Fighting the invisible enemy

There’s no getting away from them. We are constantly surrounded by invisible microbes and organisms and, for the most part, we coexist peacefully. But in a hospital environment, they can be dangerous – in operating theatres and isolation wards, particularly, they are the invisible enemy. Building services engineers need to understand the challenges for hospital infection control professionals, in order to help them achieve healthy environments for patients and staff.

Often, however, hospital staff don’t understand building services any more than engineers understand infection control. According to Craig Mackintosh, chief microbiologist of Wirral NHS Trust, the groups must work together better.

Mackintosh, who has worked in infection control for 25 years, has dedicated much time to communicating between groups involved in building and maintaining hospitals. He believes that hospital designers should be aware of the science behind NHS standards and technical memoranda in order to use them correctly. But he also thinks that these standards must not be set at unnecessarily high levels.

One of the key issues is that much of the research on which current NHS design standards are based is very old. “Healthcare trends change, so while one generation puts emphasis on ward cleanliness in the fight against bacteria, the next will move towards hand hygiene instead,” Mackintosh explains.

“When the standards were written, ventilation and air hygiene had had their day, so it wasn’t a main concern. We haven’t kept up with any advances there may have been, particularly in areas such as ventilation. This means that rather than a properly researched scientific viewpoint, based on good experimental evidence, unsubstantiated opinions are allowed to predominate.”

Fundamentally, there is a lack of understanding within the hospital environment about ventilation systems (particularly in areas such as operating theatres or isolation wards). According to Mackintosh, the original rationale of operating theatre ventilation has been lost. “At the same time, we have seen cutbacks in hospital estates and facility management teams, which means few people have the specialist knowledge required and therefore come to rely heavily on suppliers and contractors for information and knowledge in this area.”

However, relying on the current standards as they are written is no guarantee of efficient or effective design. According to Mackintosh, reliance on standards without thorough understanding of the science behind them, leads to problems. “The standards are divorced from the experimental work and the logic that underpins them, which means that we have lost the link between our ultimate objectives and the directives for design, testing and maintaining systems in general.”

This creates further problems, as construction teams claim to build to ‘standard’ but often don’t understand fully what overall objective they are aiming for. “This ‘standard’ is full of ambiguity. What happens is that people look at one aspect of the standard, so they may achieve part, but not all of it,” he explains.

Mackintosh says that the aim should be to achieve balance. Engineers and designers must take a holistic view of what they are designing. This means that, while engineers should understand infection control, they must not be hamstrung by standards which are too strict. “Too often the infection control nurse, the surgeon or estates person will expect absolute guarantees, for example no transfer of air between two areas. The problem is that real life isn’t like that. Our risks are on a sliding scale, there is never an absolute,” he observes.

There is a law of diminishing returns which says there is a point beyond which no meaningful improvement in infection control can be made. Mackintosh stresses that ‘adequate’ should be the general goal, though this is a controversial view: “The general public thinks that ‘adequate’ isn’t good enough! We are very conscious of this in the health sector, and therefore we try to design to absolutes. But really, the only absolute guarantee would be welding the door shut.”

Engineers who want exact instructions for healthcare design will be disappointed by Mackintosh’s ideas. However, he sees problems with standards that are too prescriptive.

“If we set standards that are too high and absolute, we will be trapped. Not because a system that fails is unsafe scientifically or practically, but because it will risk litigation. The difficulty is the level of angst generated by estates staff who discover, say, that a pressure differential is 24 Pascals rather than the planned 25, because they don’t realise its significance, or lack of it. Lack of understanding generates fear and blame.”

The other side to this is that in trying to meet strict standards, engineers will over-design to ensure they meet specifications. In excess, this leads to unworkable systems, such as doors that don’t open easily because of the high pressure differential.

Mackintosh is sympathetic to the challenges of building design and engineering. “There is a saying in healthcare that every operation is an experiment in surgery, because individuals are all subtly different. In the same way, every building is different because of the number of variables that exist.”

Sharing resources

Research into ventilation and design of hospital areas such as operating theatres has been undertaken recently. However, Mackintosh believes that without a comprehensive and structured approach, these pockets of research fail to give anyone a full picture. This leads to a skewed view of what factors are important in hospital hygiene, and how all the factors affect one another. “There are mythologies and rituals which arise because people think they know why something works, but they’ve got it wrong.”

However, he is not unsympathetic to these ways of working. “The problem is that since we’re dealing with invisible organisms we don’t know how many there are in the environment, or where they are.”

Mackintosh sees computational fluid dynamics as potentially very helpful in the design of operating theatre ventilation systems. “There are factors we don’t understand and more research is needed. CFD could help remove the uncertainties in ventilation design and give us a clearer picture of what’s happening, giving us a much more scientific basis for design.

“The difficulty I see is that no one is learning from experience,” he continues. “We are each learning from individual projects, but there is no national forum for sharing this knowledge.”

At the moment, exchange of knowledge in this area is indeed rare. While infection control experts (usually nurses) are invited to meetings with the construction team, this is not always successful as they don’t necessarily understand construction jargon or ventilation systems.

Mackintosh wants to see more interaction and co-operation. “This doesn’t mean anyone has to be an expert in another field. They need to know enough to be able to ask the right questions and not feel awkward. Engineers need to know what the right answers should look like, and then which experts to ask.”

A team, including Mackintosh, has set up a course at Leeds University which will explain the basics of ventilation to relevant healthcare professionals. The aim is to create groups within NHS Trusts who have a common understanding of objectives and how to attain them.

Designing for healthcare is a big challenge. It requires a lot of confidence to interpret design guidance and assess risk on a sliding scale. But the alternative is highly prescriptive requirements that serve neither designer or client well – they lead to expensive and often over-engineered solutions with the increased possibility of litigation given the slightest slip away from very high standards. Neither side wants this.

As with many issues in construction, the solution lies in better and closer consultation on all sides. Mackintosh agrees wholeheartedly: “I believe in co-operation. We need to share a common language and understanding for there to be meaningful dialogue.”