Watch out!

Constant Online Monitoring of Air Quality in the Operating Cleanroom – During Surgery

Between 2 and 10 percent of all operated patients in Germany can expect a postoperative wound infection. To reduce this risk, operating rooms use laminar flow systems with low-turbulence airflow to displace airborne germs. The critical period for infection risk is particularly the incision and suturing phase of the operation. Weiss Climate Technology presents a system at Medica that continuously monitors the actual air quality during surgery – and can correct it if necessary.

Anyone undergoing surgery in a hospital – even a routine procedure that is usually uncomplicated – is, as is well known, at risk of developing a wound infection afterward. This undesirable postoperative complication affects approximately 2 to 10 percent of all operated patients. Hospital hygiene measures therefore focus primarily on the operating room: It must be prevented that particles and bacteria enter open wounds or even the surgical field and instrument table – pre- and intraoperatively. The sources of germs vary: the patients themselves and the operating room staff bring them in – and thus they are also present in the air.

Air Attack via Dust Particle

Particularly the last group of germs cannot be easily warded off by standard hygienic measures. They are not airborne themselves – but they sit on dust particles that swirl through the air. Their danger is often underestimated: because dust particles can not only serve as vehicles for germs. They can – as a reaction of the body's immune system – also lead to adhesions in muscle tissue: inclusions of particles in tissue are meant to make them harmless. This can become especially dangerous when it involves areas where the muscle attaches to the bone: here, even the development of small nodules can lead to immobility.

Therefore, it is generally necessary to reduce particles, ideally eliminate them completely. In operating rooms with high requirements for germ-free conditions, a constant displacement airflow is installed over the surgical area to remove particles. This technique has proven successful in practice, as studies such as those by Lidwell have shown: the number of postoperative infections can be significantly reduced with it.

The operating principle is simple: A so-called laminar flow system installed on the ceiling of the OR introduces particles and thus germ-free air toward the floor. To prevent the spread of particle-borne germs from being further facilitated by additional air turbulence, the airflow must be just right: it must be strong enough to carry particles out of the surgical field. The solution is called “low-turbulence displacement airflow” (TAV). It can reduce the particle load to 1% of the otherwise typical concentration.

How Particle-Free is the OR?

How effective this technology actually is in individual cases depends on the specific conditions on site – especially on the actual air quality during the critical incision and suturing phase, as Rupert Mack, Sales Manager at Mediclean from Weiss Climate Technology, explains. However, air quality is usually only comprehensively tested once – before the handover of a new or renovated operating room to the user. At this time, a turbulence or protection level measurement is carried out according to DIN 1946-4 standards. And this means that the measurement is done with the room empty: without staff, without operating table, and without instruments.

Of course, practice looks different: the quality of the air depends significantly on how many people are in the room and how they behave. These factors influence the low-turbulence airflow. The same applies to how the operating and equipment tables as well as lamps are positioned in the room. How the air quality actually is during surgery, how it changes during this time – in short: how efficient the airflow is – remains unclear.

Measure, Correct, Document

Weiss Climate Technology has now developed a method to actively measure the efficiency of laminar flow, i.e., low-turbulence airflow, directly in the surgical field – using high-quality measurement sensors (MWA) that record particle contamination. This allows the surgical team to always have detailed information on whether sufficient particle-free and thus “airborne germ-free” conditions are maintained in the surgical field.

However, a second step is crucial for air quality: the developers at Weiss Climate Technology have perfected their method by linking the measurement results to a control loop that regulates the generation of low-turbulence airflow. If the target values regarding particle contamination are exceeded, the system initiates adjustments to the airflow. This is achieved by the laminar flow system regulating the air outlet, its speed, and thus the amount of air. Manual control by personnel, triggered by visual or acoustic signals, is also possible. This gives the surgical team an unprecedented quality assurance option on the market.

“Through continuous online monitoring and the corresponding ongoing, situation-appropriate regulation of the airflow, we ensure that particle and germ load during the critical incision and suturing phase is kept as low as possible,” summarizes Rupert Mack: “This can significantly help reduce the number of postoperative infections caused by airborne germs.”