Novel Techniques for Excellent Air Cleanliness in an Operating Theatre and a Cardiac Catheterization Laboratory

Transcription

1 Novel Techniques for Excellent Air Cleanliness in an Operating Theatre and a Cardiac Catheterization Laboratory ir Ludo VEREECKEN 1*,MSc, Frédéric VAN HEUVERSWYN 2, MD, 1 Ghent University Hospital, Head of Project Management, 2 Ghent University Hospital, Head of Interventional Cardiology Department

2 How to prevent surgical site infections (SSIs) Reliance on antibiotic prophylaxis is a dead end (antibiotic-resistant bacteria) High performance surgical clothing system Good manners of practice (reduced door openings per surgery, number of people in the room, ) Excellent air cleanliness Thermal and acoustic comfort (temperature and air velocity, noise of ventilation systems) decrease stress for staff (indirect impact on SSIs) 2 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

3 How to define or measure ultra clean air? Two basic requirements No infection due to pollution during the intervention No infection due to cross contamination Rest conditions* General room cleanliness level ISO 5 (EN ISO 14644) Recovery Time (100:1) < 15 minutes Operation conditions* < 10 CFU /m³ (CFU, colony forming unit active sampling) * CEN TC156 WG18, Hospital Ventilation Working Draft 3 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

4 Assumptions of LAF (golden standard) or UDF (UniDirectional Flow) Laminar Air flow (UDF) Unidirectional low turbulence (Charnley s principle*) No interference of the air currents Full side curtains Only protection under the LAF field Washing effect, avoiding mixing with surrounding air Are these assumptions fulfilled in state-of-the art hybrid OR? * Br J Surg.1964 Mar;51: / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

5 Assumptions of LAF not fulfilled in hybrid OR: a problem? 5 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

6 UDF/LAF is sensitive to obstacles 6 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

7 CFD Materials & Methods Computational Fluid Dynamics shows flow patterns calculates CFU/m³ predicts comfort of staff CFD ANSYS* CFD software Steady State analysis with SST turbulence model (shear stress transport) CFUs modeled as solid particles injected from staffs face and feet areas Computational models had approximately 6 million elements * Ansys, Inc. Canonsburg, PA, USA 7 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

8 Disturbance of air flow UDF/LAF due to operation lights (CFD) UDF/LAF Airflow path disrupted by surgical lamps creates stagnant area (blue fields) parallel down-flow of clean air Minimum turbulence in operation zone Still good washing effect due to 100 ACH 8 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

9 Turbulent mixing airflow (TMA) No removal of airborne BCP s Relies on the dilution principle Less sensitive to surgical lamps Works quite well +60 ACH 9 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

10 Temperature controlled airflow ( TcAF Opragon/Avidicare) 10 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

11 Less disturbance of air flow TcAF due to operation lights (CFD) TcAF Strong down-flow air stream in operating zone Accelerated by gravity: max speed at face level Small stagnant area beneath the lamps Minimum turbulence in operation zone Good washing effect at 47 ACH Vortex in perifery 11 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

12 Comparison of CFD simulated airborne contamination Good air quality for TcAF at operating table even at low ACH at instr. table at +60 ACH slowly dependent on ACH Good air quality for UDF/LAF at operating table at 100 ACH at instr. table at 100 ACH highly dependent on ACH Good air quality for TMA at operating table even at 60 ACH at instr. table at 60 ACH highly dependent on ACH 12 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

13 Comparison of measured airborne contamination during 45 orthopaedic procedures Good air quality for TcAF 46 ACH at operating table at instr. table also in periphery Good air quality for UDF/LAF 100 ACH at operating table at instr. table NOT in periphery Bad air quality for TMA 26 ACH at operating table at instr. table in the periphery 13 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

14 Design of a hybrid Cathlab in University Hospital Ghent Computational Fluid Dynamics Modelling of complex procedure: worst case scenario C-arm has a large disturbance on Charnley s principle 6 staff in the room Lots of devices and instrumentation tables Behaviour of UDF/LAF was not found for hybrid ORs in literature 14 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

15 TAVI procedure Aortic valve stenosis = most common cardiac valve lesion TAVI = transcatheter aortic valve implantation Alternative for open surgical aortic valve replacement in selected patients with high operative risk 15 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

16 TAVI Procedure requires optimal fluoroscopic image quality in a perfectly sterile surgical environment Catheter is advanced over the wire from the femoral artery through the calcified aortic valve After balloon dilatation of the stenotic valve the new valve is placed inside the native valve Positioning of the valve requires rapid cardiac pacing to temporarily stop the pump function of the heart 16 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

17 Halton Vita OR Space: controlled dilution air flow (cdaf) 17 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

18 Comparison of UDF/LAF and cdaf 42 ACH Green rectangle LAF 1,8 x 2,4 m Blue Ring: nozzles in Vita solution Computational Fluid Dynamics Simulation using ANSYS* CFD software Critical zones Red Areas (wound area and instrument table 1 and 2) The UDF/LAF corresponding to the same air flow (about 5000 m³/h ~42 ACH) average velocity 0,32 m/s 18 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

19 Results UDF/LAF 1,8 x 2,4 m² 42 ACH: air flow Field 1,8x2,4: no laminar flow in plane 2, velocities 0,3 m/s upwards (even underneath the LAF-field) due to C-arm Required surface to cover all critical zones = 4,2 x 5,6 m² airflow at average velocity 0,33 m/s m³/h: +200 ACH not feasible 19 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

20 Results UDF/LAF 1,8 x 2,4 m² 42 ACH microbial cleanliness Microbial Cleanliness 0,9 m plane No control of flow of the air No uniformity Good Q wound area Bad Q on instr.table esp / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

21 Results cdaf 42 ACH: air flow Good flow in the wound area Controlled air flow over the patient Nice air distribution on the instrumentation tables 21 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

22 Results cdaf 42 ACH microbial cleanliness Microbial Cleanliness 0,9 m plane Much more uniform conditions All critical zones are covered Also good area at the feet of the patient 22 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

23 Comparison cdaf <> LAF/UDF Microbial Cleanliness critical areas Fullfills < 10 CFU/m³ for cdaf at wound area and instr. tables LAF/UDF: CFU too high outside of the protected area 23 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

24 Results Recovery time cdaf Average recovery time by design 7 minutes (< 15 minutes) Age of Air illustration shows a good flushing of all critical areas (Plane 3 Instrument tables) 24 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

25 Results Thermal Environment cdaf No direct draft of supply air to the operating staff (max 0,5 m/s) Air temperature more equalized due to dilution before entering the occupied zone ( 2 C higher than supply air (Plane 2 doctors)) 25 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

26 Discussion UDF/LAF and cdaf give good air quality in the wound area Only cdaf gives good air quality outside the wound area cdaf is less energy consuming than LAF 3x3 m (50%) cdaf gives better thermal environment due to dilution 26 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

27 Comparison Acoustic comfort In Ghent we measured 40 dba for cdaf 42 ACH Acoustic comfort is highly dependent on ACH 27 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

28 Validation of the cdaf (Halton Vita Space) by PMT Benelux Iso 5 in all measured points Also all other requirements passed the test 28 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

29 Conclusions 1 All challenges of patient safety must be examined when designing and building a state-of-the art OR. Rethink the applicability of UDF/LAF in a complex lab or modern OR with large obstacles and need for clean conditions in different areas of the room. UDF/LAF ~ 0,4 m/s gives still good results when Charnley s principle is fulfilled but at the cost of high energy consumption (~100 ACH) If Charnley s principle is not fulfilled, CFD calculation is absolutely necessary Important obstacles in the air flow Critical zones outside of protected area 29 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

30 Conclusions 2 TcAF (Opragon 8, Avidicare) gives promising results for OR for orthopaedic surgery if instumentation tables are within the protected zone of central diffusers We found no evidence for the use of TcAF for complex OR as hybrid operation rooms The cdaf (Vita Space Halton) solution gives good air quality even in complex OR (ceiling-mounted devices, multiple critical zones). In this solution instrumentation tables can be placed in predefined areas of the perifery Energy consumption is much lower for cdaf 42 ACH and TcAF 47 ACH Staff comfort (thermal, acoustic by design) is optimized in cdaf and TcAF Much more research has to be done to know about air flows, CFU/m³ and the effect on SSIs 30 / VEREECKEN L ET AL, 26TH DAY OF INFECTION PREVENTION, GHENT, DECEMBER 10TH 2018

31 LUDO VEREECKEN Universitair Ziekenhuis Gent C. Heymanslaan 10 B 9000 Gent T +32 (0) E info@uzgent.be Volg ons op