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Jan 26, 2023

Real-world Surgical Site Infection (SSI) rate in Germany is 4.9% – data from 4 million patients

Germany is underachieving – is it time for action?

According to a new study*, data show that between 2008 and 2016 the frequency of Surgical Site Infections (SSIs) has not decreased in Germany despite extensive regulations and standards. The overall SSI prevalence in the study period was 4.9% based on actual hospital reimbursement data from 4 million patients. Compared to the self-reported SSI rates for German hospitals of 1.08% based on the voluntary Krankenhaus-Infektions-Surveillance-System (KISS) it is apparent that the real number of SSIs has been significantly underestimated, according to the researchers.

SSIs are among the most common complications after surgery. Their occurrence is linked to the type of surgery performed with increased risk seen in orthopedics, neuro/spine and some cancers. Especially implant surgery like hip or knee replacements are at risk for SSI. 

SSIs leads to significant patient suffering and also cause:

  • premature deaths, 
  • additional surgical procedures, 
  • increased need for postoperative intensive care and 
  • longer stay in hospital. 

Thus, as a direct consequence, SSIs increase the financial burden of healthcare and drive many even larger indirect costs to society due to factors such as extended sick leave. All in all this has a significant economic impact. Therfore the importance to reduce the risk of SSIs for safer, more affordable and more sustainable healthcare is obvious!

Such high SSI numbers from a country that is assumed to provide a very high standard of care and that has well-developed standards for technical infrastructure like operating room ventilation – DIN-standard 1946-4 is surprising. It brings up several questions regarding the infection control protocols but also regarding the technical concepts for OR ventilation  One reason may be that the German standard for OR ventilation assesses systems only in an empty operating theater at rest and not in clinical operation. In rooms at rest, the primary contributors to airborne contamination, the surgical personnel, are not present. Moreover, equipment which generates heat and thus impacts thermodynamics in the room is not switched on. This is troublesome as people in the room, their movement and equipment are the major sources of airborne contamination.  If you test the system in an empy room it cannot be determined whether the ventilation system is effective in minimizing airborne contamination.

The clean zone is too small to fit all equipment.

Another reason for higher than expected SSI rates could be the dedicated clean zone concept on which LAF systems are based. The limited clean zone is often too small to protect instruments and implants and address movement in the periphery of the room. Even though the latest version of the standard demands that hospitals shall start with a positioning analysis in order to define the size of such a zone and LAF system, most operating rooms were built before this analysis became mandatory. The limited size of the clean zone has significant implications. Research shows that in only 6% to 50% of surgeries, instruments and implants can be positioned inside the protected zone**. Other research shows that the airborne bioburden outside of the protected zone is about 55x higher than in the protected zone***.  Even modern and properly operated LAF ceilings will keep the center of the operating room ultra-clean, but by design leave the rest of the room dirty. 

Moreover LAF systems need high air velocity to counteract thermal plume from staff. As for SSI, the high velocities create additional turbulence increasing the infection risk by circulating contaminated air from the periphery back to the critical spaces in the clean zone. 

In conclusion, the paper shows that despite strict technical standards and workflows the risk of infection for the patient still has not decreased. It is therefore likely time to review the existing and accepted ventilation concepts like LAF in the context of patient safety.

These limitations of existing technologies such as LAF is precisely why we developed Opragon, a Temperature-controlled Airflow System (TcAF), which combines the classic mixed ventilation with a cooled unidirectional airflow (figure1). Combining the two systems in the same operating room produces extremely effective ventilation. The technology behind TcAF is based on the ventilation system quietly releasing slightly cooled air into a zone around the operating table. By taking advantage of the fundamental laws of nature, TcAF breaks the convection currents in an effective and energy-efficient manner. Since cool air is denser than the surrounding warmer air, it drops towards the floor using gravity. The air speed is defined by the temperature difference in the room. The system enables reliable and stable control of air movements, and thereby also the airflow’s downward speed over the patient and the staff. The technology reduces the presence of bacteria-carrying particles in the operative zone while at the same time helping to create a comfortable working environment. Read more about our validated, and evidence-based research here.

Figure 1

It is time to ensure that unnecessary infections are eliminated, patient suffering is ended and that expertise in infection prevention and control must take precedence over pure technical standards. Contact us today to learn more about effective, energy efficient, safe, and ultra-clean ventilation for your medical facility.

Together Towards Zero Infections!

** Dutch study showing that only 6% of surgery stays inside the clean zone.

***Article by Benen et al. (2013)