“thinking outside the box: first experiences from the ... the research or in weidenwith a new...

“Thinking outside the box: First experiences from the research OR in Weiden with a new surgical ventilation system”

Prof. Dr. Clemens Bulitta,Chair Institute of Medical EngineeringTechnical University of Applied Sciences Amberg-Weiden, Germany

Agenda

• Research Environment• Problem and Current Situation• System Concept and Function• Material and Methods• Results• Conclusions

Research and Teaching OR

Concept: Fully equipped and fully functioning OR allows for testing, developing, demonstrating and training of available technologies (OR, medical and otherEquipment, Building Services, etc.) and their integration. The OR as a systemcan be evaluated in different settings and workflow scenarios allowing fordedicated solutions development, workflow trainings, simulation and processimprovement

Areas of Research and Teaching:‒ Workflow, Usability and User Centered Design, Training‒ Hygiene, HVAC with innovative solutions and concepts‒ Technology Development and Systems Integration‒ Hospital Planning, Automation and Building Services‒ Videomanagement‒ RFID-Deployment‒ ….

Implementation

Agenda

• Research Environment• Problem and Current Situation• System Concept and Function• Material and Methods• Results• Conclusion

What is causing deep SSI ?

• The patient undergoing a surgical procedure always taking the risk of become infected by a pathogen causing a deep surgical site infection.

• The infection could be endogenous or caused by the staff, exogenous, or via nosocomial transmission.

• The route of the nosocomial transmission could be via the surgical (sterile) instruments and/ or via the ambient air in the OR.

• Most of the pathogens are released from the staff as airborne skin flakes carrying bacteria's (CFU, Colony Forming Units).

• Common threshold levels are <100cfu/m3 or <10cfu/m3 for general or infectious sensitive surgery respectively.

…some facts…Endogenous Factors:

Patient-Flora (skin, GI-tract, existing wounds,…) microbiological colonization within surgical field microbiological colonization outside surgical field

Exogenous Factors: OR-staff (surgeon and team):

contaminated clothinginterference with asepsis„wrong“ hand hygieneParticle and cfu „shedding“ (skinflakes/dander):

ca. 5000/min walking (5 to 60 μm)ca. 10 000/min exercisingca. 5 germs per skin flake/dander

Environment and ventilation in the OR Contaminated surfaces, instruments, devices, material, …

Background: Impact of SSI

Burden-US• ~300,000 SSIs/yr (17% of all HAI; second to UTI) • 2%-5% of patients undergoing inpatient surgeryMortality• 3 % mortality • 2-11 times higher risk of death • 75% of deaths among patients with SSI are directly attributable to SSIMorbidity• long-term disabilitiesLength of Hospital Stay• ~7-10 additional postoperative hospital daysCost• $3000-$29,000/SSI depending on procedure & pathogen• Up to $10 billion annually • Most estimates are based on inpatient costs at time of index operation and

do not account for the additional costs of rehospitalization, post-discharge outpatient expenses

Anderson DJ, etal. Strategies to prevent surgical site infections in acute care hospitals. Infect Control Hosp Epidemiol 2008;29:S51-S61 for individual references

Controversial Debate

Conclusion:The available evidence shows no benefit for laminar airflow compared with conventional turbulent ventilation of the operating room in reducing the risk of S Sis in total hip and knee arthroplasties, and abdominal surgery. Decision makers, medical and administrative, should not regard laminar airflow as a preventive measure to reduce the risk of SSis. Consequently, this equipment should not be installed in new operating rooms.

Lancet Infectious Diseases:Published online February 16, 2017 http:l/dx.doi.org/10.1016/51473-3099(17)30059-2

Evidence for CFU and SSI correlation• Between 1959 until 1974 Sir John Charnley was able to reduce

the SSI after hip prosthesis surgery from 8,5% to 0,7% by reducing the cfu from 600cfu/m3 down to <1cfu/m3 (!). This by doing the surgerical procedure in his “greenhouse” or “Charnleybox” with ventilated body exhaust suites. He showed a correlation between cfu levels and SSI rate.

Evidence for CFU and SSI correlation

• In a prospective controlled multicenter study with >8 000 patients the results were later confirmed by Lidwell et al in 1993. Antibiotic prophylaxis and air cleanliness reduced the SSI independently. In the study ultraclean air was defined as <10cfu/m3

• To repeat the studies today with antibiotic prophylaxis as standard treatment will (yet) be difficult or, not to say, impossible due to the low rate of SSI we have today.

Quelle: American Journal of Infection Control xxx (2012) e1-e5, Hirsch et. alLidwell OM. Sir John Charnley, Surgeon (1911-82): the control of infection after total joint replacement. J Hosp Inf 1993;23:5-15

Comparison of the total germ immission with regard to increasing incision to closure time.

Different approach in different standards• Lack of an EU standard leaves it open for different test

methods for different countries:‒ NF S 90-351;2013‒ SIS-TS 39;2015‒ DIN 1946-4;2008 (currently under revision)‒ HTM 03-01;2007‒ VCCN RL7; 2014 (only in Dutch)

• Two major differences between the tests:‒ Measuring protection (degree) from artificial generated particles from the

outside into the clean zone (at rest) or measuring the levels of CFU generated by staff inside the clean zone (during surgery)

‒ Measurements at rest or in operation state during surgery with a “knife time” of >45 minutes to reach steady state conditions

• What will be closest to the real life situation?

Agenda


What is the basic thinking and rationale behind Opragon

• Most surgical procedures have a similar “set-up". The patient on the operating table, 3-5 sterile dressed staff around the patient, 1-2 anesthesia staff at the patient's head end and 1-2 other staff elsewhere in the operating room.

• The majority of the generated cfu´s are released very close to the wound and the sterile instruments and must be transported away from there

• The effect of the convection currents from staff is often neglected.

OPRAGON

EXTERNAL AIRSHOWER

BODY CONVECTION

CFU – GENERATING STAFF

What is needed to break the body convection currents?

But Gravity is “superior”…

• By utilizing air that is 1-1,5 degree below the room temperature at the height of the OR table, combined with special designed extreme low impulse airshowers, the system can create a very powerful and reliable down flow over the OR-table, sterile dressed staff and instrument tables.

• Temperature or gravity controlled airflow is less sensitive to heat loads and/ or obstacles in the OR area.

OPRAGON

EXTERNAL AIRSHOWER

Thinking outside of the Plenum….

ULTRACLEAN AIR IN THE WHOLE

ROOM

And the result is….

How to get low levels of CFU in an operating room?

• Reduce the "emissions" at the source through dense clothing and/ or the number of staff in the OR.

• Concentrations of cfu can be reduced through effective ventilation, there are two main principles:‒ Turbulent mixing, diluting principle (Class 1b)‒ Parallel flow, away transporting effect, “sweeping action”

(Class 1a)• TAF (Temperature Controlled Air Flow) is a combination of

these two principles (Class ?) with a high ventilation efficiency as a result, which leads to low cfu levels in the WHOLE operating room.

System setups

Agenda


Material and Methods: CFD – SimulationCAD-Model Research OR OTH

CFD – PostprocessingTop: Velocity (y-side view: center) Bottom: Protection degree (y-side view: center)

CFD – PostprocessingTop: Particle load (y-side view: center) Bottom: Coldair-Distribution

Validation of CFD-Simulation with smoke

MeasurementsDIN 1946-4 (2008)

Measurements SIS-TS 39 (2015)

Active Airsampling and MicrobiologicalAssessment

Agenda


CFD Simulation

Source:Malin Alsved, Lund UniversityUlmer Hygienekongress 3/2017

Protected area Opragon 22

Protected area Opragon 8

Protection Degree According toDIN 1946/4

Active Airsampling

Comparison CFU/m3:No Vent – TAF – TAV – TML

CFU

/m3

No Vent

(cumulated data)

Active Airsampling duringSurgery


Survey environmental conditions


Summary of Results

• TAF System in compliance with protection degree requirements according to DIN 1946-4 (2008) for class 1a

• TAF System in compliance with CFU measurements according to SIS-TS 39 (2015) for infection sensitive clean surgery

• TAF System in Compliance with ISO Class 5 according to ISO 14644-1 (2014)

• TAF System in Compliance with GMP Class B according toEU-GMP 2008

• TAF System controls cfu burden in the entire room• TAF system provides „comfortable“ working environment

Agenda


Conclusions

• TAF Sytem fulfills important international hygienic standardsfor ventilation systems

• TAF System combines advantages of mixing andunidirectional ventilation systems

• TAF System significantly reduces microbial and particleburden in Operating Theatres in the ENTIRE room

• Staff comfort subjectively higher, assessment according to DIN EN ISO 7730 necessary

• Energy savings based on reduced air volume can be achieved. Further detailed studies are required

• TAF is a viable and hygienically effective alternative to Laminar Airflow and other ventilation systems

Questions ???

Acknowledgements:Avidicare for supporting the research

“thinking outside the box: first experiences from the ... the research or in weidenwith a new...

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