Skip to main content
Oct 19, 2021

Research you should know: How to protect instruments and implants at all times in a LAF/UDF operating room

Summary of Prof. Dr. Bulittas presentation at Medicinteknikdagarna 2021

In an OR room the clean zone should be dimensioned according to the worst-case surgical scenario to secure that you always protect both patients, staff and instruments

The purpose of the ventilation system is to ensure occupational and patient safety that minimize the risk of infections and create a good working environment with adjustable temperature adjustment, little noise and low draught. It must also be robust since the efficacy of the ventilation is challenged by human behavior and clothing protocol. 

During Medicinteknikdagarna in Sweden on the 5th-6th of October 2021, Prof.Dr. Clemens Bulitta presented his abstract about the importance of positioning analysis when considering LAF/UDF for operating rooms, read the full abstract below: 

Workflow and positioning analysis are critical for planning and designing low turbulence displacement or laminar airflow OR ventilation systems

Clemens Bulitta, Technical University of Applied Science Amberg-Weiden, Hetzenrichter Weg 15, 


Ventilation technology in German operating rooms is regulated by DIN 1946-4. Since the release of the latest version in 2018, a positioning analysis (worst-case scenario with the largest space requirement) for low turbulence displacement or laminar airflow systems (LAF) is mandatory. The aim of this investigation was to use typical workflow scenarios to assess existing installations regarding the match of the required and the built situation.


Positioning and workflow analysis were carried out together with the on-site staff for various clinical procedures in different hospitals to assess the situation. For this purpose, the protected area specified by the installation was marked and then the room was prepared according to the usual clinical procedure on site. Any differences between the existing and actually required protected area were recorded and measured, as well as the effects on room size and ventilation system. 


The positioning analysis revealed that required protected areas need to be significantly larger than provided by the existing setup. Typically, an average of at least approximately 4.00 m x 4.00 m is required to ensure appropriate protected areas for most interventions.


Individual workflow and positioning analysis is critical for planning and designing proper LAF systems. Most existing LAF installations are likely to be too small. The larger protected areas actually require significantly larger rooms in order to maintain proper thermodynamics. Furthermore, significantly higher volumetric flow rates are required. Finally, the current mismatch between actual and necessary protected areas would be a possible explanation for the controversial data regarding the infection protective effects of LAF systems. This also shows the need to consider alternative ventilation systems like temperature controlled airflow (TcAF) which cater to a holistic approach for creating the entire OR space as a protected area with less energy.

SSI guidance requires placement of surgical instruments, implants, and devices within the protected zone.
How often is this requirement met in your facility? 

This positioning analysis is not required with temperature controlled airflow (TcAF) since the whole OR is ultra-clean, which gives the staff a highly flexible workflow with many options for placement of instrument trays and devices. 

LAF is challenged by obstacles whereas TcAF ā€œnavigatesā€ obstacles and maintains downward airflow.

With these constraints, many now chooseĀ alternative ventilation systems like temperature controlled airflow (TcAF) which are designed to overcome the challenges of LAF/UDF.

Left: Turbulent/Mixing Ventilation, Middle: Laminar Airflow (LAF/UDF), Right: Temperature controlled Airflow (TcAF)
Source: M. Alsved et al. / Journal of Hospital Infection 98 (2018) 181-190

Click here if you want to know more about TcAF and Opragon, the sustainable and efficient ventilation system.