SURGICAL S I T E INF ECTION
However, an operating theatre is an extremely complex system, and mitigating infection risks – especially at a time when the world is battling a highly infectious virus – requires a holistic approach that considers every single aspect of the operating room. “This is due to the nature of SSIs, which occur when harmful germs enter the body through the incision in the skin, from contaminated surfaces and instruments, and from the air. In fact, it has been suggested that the main sources of contamination in operating rooms, especially in clean surgical procedures, are the patient’s skin and airborne particles from operating room personnel.” 8
Optimising laminar airflow Laminar airflow systems (LAF) use positive pressure air currents to direct air streams away from the operative field and create an ultraclean zone around the operative site. The systems were pioneered by Sir John Charnley in the 1960s and 70s and have been shown to result in a marked decline in post-operative wound infection9
when used
in conjunction with other strategies. More recently, research has shown that the presence of surgical lights disturbs the flow of ultraclean air in operating rooms with vertical laminar airflow systems, by creating a wake downstream of the lights.10
This then directly
influences the level of airborne microbe- carrying particles close to the surgical site, eventually leading to SSIs. An experimental study11
– the first of its kind – in 2017
Jyrki Nieminen, Director of R&D, Merivaara
showed that surgical lights have a significantly negative effect on laminar airflow. “Traditional surgical light heads cause air to rise in the operating area, resulting in increased particle content and an increased infection burden for the patient. Essentially, they create turbulence intensity, acting like an aircraft wing to pull particulates in the air right over the patient,” Nieminen explained. “It is important to note that while airflow can be managed, it can also be disturbed. The shape of lamp heads or lighting systems affect airflow. Hospitals can spend huge amounts of money on ventilation, but this is
a waste if it’s not compatible with the light. Currently, there is a lack of research in this area and the correlation between surgical lighting and laminar airflow is still poorly understood,” he continued. When it came to designing Q-Flow, the first step was understanding airflow and how exactly it works in operating rooms, and assessing the effect of different surgical lights. Designers shaped the surgical light as a series of concentric circles with open spaces in between. The distinctive design was chosen for its ability to reduce turbulence when compared to more standard shapes, thus helping to push more clean air towards the patient. “The research that we carried out brought to light the ways in which the shape and design of surgical lights can impact laminar airflow – and how best to limit the negative effects. “Laminar airflow effectively equates to reduced turbulence of harmful airborne contaminants,” Nieminen explained. “Q-Flow’s shape allows air to flow through it, so that air will not circulate above the patient; thus, it enhances the patient’s safety during operation. The designs were also tested by surgeons, anaesthesiologists and nurses who collectively gave us their input throughout the design process.”
Research and development Nieminen explained that the initial theory of changing the shape of the surgical light was based on research conducted by aerodynamic experts. An example of such studies is the ‘Aerodynamics of High Performance Vehicles’ study carried out by the Department of Mechanical Engineering in India in 2018. Although this particular study focused on racing cars, it showed the characteristics of aerodynamics and the effects that different shapes have on airflow. The different methods used within the research calculated aerodynamic forces, offering an insight into how differently shaped operating lights might impact airflow in a clinical setting and, most importantly, what effect this would have on patients lying underneath them. It was theories like this that highlighted to Merivaara the importance of developing a light head shape which was cylindrical in cross-section.
Q-Flow laminar airflow
It is important to note that while airflow can be managed, it can also be disturbed. The shape of lamp heads or lighting systems affect airflow. Hospitals can spend huge amounts of money on ventilation, but this is a waste if it’s not compatible with the light.
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Nieminen said: “It was clear from aerodynamic research that flat head shapes create a disturbance to air flow, which actually reverses air flow. In practical terms this would mean that in an operating theatre any clean air flow that was being pumped into the room would be pushed away from the patient rather than going directly to them, creating an infection control risk. “With this in mind we were advised against developing the standard flat shaped light which was common in most operating theatres at that time and create a different
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