An analysis of bioaerosol emissions from orthopaedic surgical clothing

AN ANALYSIS OF BIOAEROSOL EMISSIONS FROM ORTHOPAEDIC SURGICAL CLOTHING Dr Praveen Vijaysegaran MBBS/B Med Sci (University of Melbourne) Orthopaedic Registrar, Royal Australasian College of Surgeons Submitted in fulfilment of the requirements for the degree of Master of Applied Science Institute of Health and Biomedical Innovation Queensland University of Technology 2016 An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing Keywords Orthopaedics, space suit, clean air, arthroplasty, prosthetic joint infection An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing Abstract Introduction: The role of space suits in the prevention of orthopaedic prosthetic joint infection remains unclear Recent evidence suggests space suits may in fact contribute to increased infection rates, with bioaerosol emissions from space suits identified as a potential cause This study aimed to compare the particle and microbiological emission rates from space suits and standard surgical clothing Methods: A comparison of emission rates between space suits and standard surgical clothing was performed in a simulated surgical environment during five separate experiments Particle counts were analysed with two separate particle counters capable of detecting particles between 0.1 and 20 µm One microbiological sampler was used, with culture counts performed at 24 and 48 hours Results: Four experiments consistently showed statistically significant increases in both particle and microbiological emission rates when space suits are used compared with standard surgical clothing One experiment showed inconsistent results, with a trend towards increases in both particle and microbiological emission rates when space suits are used compared with standard surgical clothing Conclusion: Space suits cause increased particle and microbiological emission rates compared with standard surgical clothing This finding provides mechanistic evidence to support the increased prosthetic joint infection rates observed in epidemiological studies An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing Table of Contents Keywords Abstract Table of Contents Error! Bookmark not defined.3 List of Figures List of Tables Error! Bookmark not defined.6 List of Abbreviations Statement of Original Authorship Acknowledgements Error! Bookmark not defined Chapter 1: Introduction and Literature Review 10 1.1 Total hip and knee joint arthroplasty 10 1.2 Prosthetic joint infection 11 1.3 The clean air hypothesis 13 1.4 Causes of increased infection rates 17 1.5 Hypothesis and aim 18 Chapter 2: Research Design Error! Bookmark not defined 2.1 The simulated surgical environment 19 2.2 Measurement devices 22 2.3 Experiment protocol 26 2.4 Emission rate analysis 30 An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing Chapter 3: Results 31 3.1 Particle emission rates 31 3.1.1 Experiment Results 32 3.1.1 Statistical comparison 35 3.1.2 Combined graphs 37 3.2 Microbiological emission rates 40 3.1.1 Experiment Results 41 3.1.2 Statistical comparison 43 3.1.2 Combined graphs 45 Chapter 4: Discussion 46 4.1 Increased emission rates 46 4.2 Limitations of study 49 4.3 The future of space suits 52 4.4 Conclusion 54 Chapter 5: References 55 Chapter 6: Appendix 63 An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing List of Figures Figure 1: Sir John Charnley in a body exhaust suit 14 Figure 2: Spirometry chamber and inlet 20 Figure 3: HEPA filtered clean air supply 20 Figure 4: Spirometry chamber and outlet 21 Figure 5: OPC particle counter 23 Figure 6: UVAPS particle counter 23 Figure 7: Andersen cascade impactor and pump 24 Figure 8: Space suit clothing equipped 27 Figure 9: Space suit clothing unequipped 27 Figure 10: Standard surgical clothing equipped 28 Figure 11: Standard surgical clothing unequipped 28 Figure 12: Mean of UVAPS particle emission rates equipped space suit vs standard 37 Figure 13: Mean of UVAPS particle emission rates unequipped space suit vs standard 37 Figure 14: Mean of OPC All particle emission rates equipped space suit vs standard 38 Figure 15: Mean of OPC All particle emission rates unequipped space suit vs standard 38 Figure 16: Mean of OPC Large particle emission rates equipped space suit vs standard 39 Figure 17: Mean of OPC Large particle emission rates unequipped space suit vs standard 39 Figure 18: Mean of microbiological emission rates at 24 hours 45 Figure 19: Mean of microbiological emission rates at 48 hours (Experiement not read at 48 hours) 45 An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing List of Tables Table 1: A summary of the space suit literature 16 Table 2: Particle emission rates for experiment 32 Table 3: Particle emission rates for experiment 32 Table 4: Particle emission rates for experiment 33 Table 5: Particle emission rates for experiment 33 Table 6: Particle emission rates for experiment 34 Table 7: UVAPS particle emission rates equipped space suit vs standard 35 Table 8: UVAPS particle emission rates unequipped space suit vs standard 35 Table 9: OPC All particle emission rates equipped space suit vs standard 35 Table 10: OPC All particle emission rates unequipped space suit vs standard 35 Table 11: OPC Large particle emission rates equipped space suit vs standard 36 Table 12: OPC Large particle emission rates unequipped space suit vs standard 36 Table 13: Microbioloigcal emission rates for experiment 41 Table 14: Microbioloigcal emission rates for experiment 41 Table 15: Microbioloigcal emission rates for experiment 42 Table 16: Microbioloigcal emission rates for experiment 42 Table 17: Microbioloigcal emission rates for experiment 43 Table 18: Microbioloigcal emission rates at 24 hours 44 Table 19: Microbioloigcal emission rates at 48 hours 44 An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing List of Abbreviations CFU Colony forming units ER Emission rate HEPA High-efficiency particulate air MER Microbiological emission rate OPC Optical particle counter PER Particle emission rate UVAPS Ultraviolet aerodynamic particle sizer An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing Statement of Original Authorship The work contained in this thesis has not been previously submitted to meet requirements for an award at this or any other higher education institution To the best of my knowledge and belief, the thesis contains no material previously published or written by another person except where due reference is made I undertake to retain the original collated data on which this thesis is based for a minimum of five years, in accordance with University ethics guidelines QUT Verified Signature Signature: _ August 2016 Date: _ An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing Acknowledgements First and foremost, I would like to thank my principal supervisor Professor Ross Crawford, for all your support and guidance, and for constantly serving as an inspiration I would not be where I am today if it was not for you To Dr Luke Knibbs, thank you for being so accommodating and always having a solution to all my problems You have been my go-to guy over the last few years Professor Lidia Morawska, thank you for this opportunity and your encouragement To all my family and friends who have supported me throughout, particularly my parents and in particular my father Vijaysegaran Shanmugam who spent many long hours experimenting with me, thank you Almost everything I is for you, and to make you proud Kathleen Capehart and Navina Vijaysegaran, thank you for getting me over the finish line and all your help with editing I would also like to express my gratitude to all my other colleagues at QUT and elsewhere who have helped over the last few years Dr Sarah Whitehouse, Dr Graham Johnson, Dr Timothy Kidd, Chantal Labbe and Monica Warzywoda, this research would not be possible without your help And to everyone else who played a role, however trivial or insignificant, your efforts have been much appreciated An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing infection prevention The use of space suits for personal protection has more merit, with studies showing a high rate of surgeon and clothing contamination with the surgical site as the primary source during total knee and hip arthroplasty48, 49 The recent literature on space suits and their role in the surgical setting has suggested that space suits should be used primarily as a form of self-protection and not as an infection prevention tool44 Based on the findings of this study and the potential explanations, surgeons who choose to use space suits as a form of self-protection can implement a number of steps to potentially reduce the potential for causing infection Firstly, all gown interfaces which could serve as an external conduit for emissions, particularly those coming into close contact with the surgical field such as the surgeon’s hands (gown/glove interface) should be sealed air tight, and exhaust air routed through a single pathway which is either filtered or discharged such that it cannot contaminate the surgical field This has been highlighted in the literature recently, with measures such as sealant tape having been recommended25, 26 Further headgear should be used to cover as much as the surgeon’s face as possible including ears and eyebrows, such as the balaclava used with standard surgical clothing Surgeons using space suits should also pay meticulous attention to their surroundings and have a heightened sense of spatial awareness Unnecessary movements generating excess particles should also be avoided Modification to current space suit instrumentation and other operating room equipment may also potentially help reduce emission rates Bulky space suit helmets and hoods should be modified, and excessive hood material should be avoided A translucent hood material may help with a surgeon’s spatial awareness Negative pressure suits with outlet tubing are no longer commercially available but modifications to existing suits such as the implementation of an exhaust fan within the gown that expels emissions towards a specific location away from the surgical field may also be useful An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 53 The use of laminar flow systems and similar devices which blow clean air onto and away from the surgical field may also be of benefit Large clinical studies dating back to Lidwell’s trial in the 1970s showed lower infection rates (1.5% vs 0.56%) when laminar flow was used in conjunction with modified surgical clothing (body exhaust suits)21, 22 Recent nationwide registry data has also shown a slight but clinically significant reduction in infection rates when space suits are used in laminar flow theatres compared to conventionally ventilated theatres A combination of these measures should be employed to limit the effect of the potentially harmful emissions of space suits when they are used The potential exists for a number of different areas to be researched based on the findings of this study A study assessing the flow of bioaerosols emitted by surgeons and surgical clothing has yet to be performed The clinical significance of bioaerosols and their impact on prosthetic joint infection rates also requires further research Finally, a comparison between positive and negative pressure clothing systems (ie body exhaust suits and space suits) would be of value, as this is an important mechanism contributing to the results of this study 4.4 Conclusion Orthopaedic prosthetic joint infection rates may be affected by the emissions of orthopaedic surgical clothing This study compared the emission rates of space suits to standard surgical clothing, via laboratory based methods of particle and microbiological An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 54 counting, in a simulated surgical environment The results of this study consistently showed statistically significant increases in particle and microbiological emission rates when space suits are used compared with standard surgical clothing These findings can be used to inform the choices made by surgeons about their clothing Surgeons should proceed with caution when using space suits during surgery, particularly total joint arthroplasty Chapter 5: References An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 55 [1] Salaffi F, Carotti M, Grassi W Health-related quality of life in patients with hip or knee osteoarthritis: comparison of generic and disease-specific 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J Bone Joint Surg Br 2011 Jan; 93(1): 85-90 [45] Knibbs LD, He C, Duchaine C, Morawska L Vacuum cleaner emissions as a source of indoor exposure to airborne particles and bacteria Environ Sci Technol 2012 Jan 3; 46(1): 534-42 [46] Owers KL, James E, Bannister GC Source of bacterial shedding in laminar flow theatres J Hosp Infect 2004 Nov;58(3):230-2 [47] Whyte W, Hodgson R, Tinkler J The importance of airborne bacterial contamination of wounds J Hosp Infect 1982 Jun; 3(2): 123-35 An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 62 [48] Singh VK, Kalairajah Y Splash in elective primary knee and hip replacement J Bone Joint Surg Br 2009 Aug;91(8):1074-7 [49] Alani A, Modi C, Almedghio S, Mackie I The risks of splash injury when using power tools during orthopaedic surgery: a prospective study Acta Orthop Belg 2008 Oct; 74(5): 678-82 [50] Kulkarni P, Baron PA, Willeke K Aerosol measurement: principles, techniques, and applications 3rd ed Hoboken (NY): Wiley; 2011 Chapter 6: Appendix Aspiration efficiency calculations were performed for all channel sizes on both the particle counters and the air sampler based on standard methods for calculating aerosol transport in sampling lines and inlets50 An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 63 Velocities: Vi = Air velocity in the inlet Vw = Velocity range through the chamber exit where the sampling head was placed for all experiments combined: Velocity mean/range per experiment: 1) 0.775 m/s (0.40-.0.92 m/s) 2) 0.464 m/s (0.43-0.48 m/s) 3) 0.416 m/s (0.40-0.44 m/s) 4) 0.431 m/s (0.42-0.45 m/s) 5) 0.409 m/s (0.40-0.43 m/s) Thus range (Vw) = 0.409 – 0.775 m/s Tube Lengths: Common sample tube - 237mm OPC tube - 448mm UVAPS tube - 417mm UVAPS/OPC Measurements: Flow rate UVAPS – litres/min Flow rate OPC – 28.3 litres/min Flow rate combined – 33.3 litres/min Inlet Diameter – 0.004m Air velocity in the inlet (Vi) - 44.20970641441095007627071495526 metres/sec An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 64 Vw/Vi - 0.009251362 to 0.017530087 Andersen Measurements: Flow Rate – 28.3 Inlet Diameter – 0.025 Air velocity in the inlet (Vi) - 0.96087144309346943912388539301682 metres/sec Vw/Vi - 0.425655277 to 0.80655951 Aspiration Efficiencies: OPC: 0.1µm - 0.999382448% to 0.999371663% 0.2µm - 0.998394334% to 0.998366335% 0.3µm - 0.996991085% to 0.996938731% 0.5µm - 0.992918997% to 0.99279656% 1.0µm - 0.975669038% to 0.975259554% 5.0µm - 0.645265672% to 0.642400684% UVAPS: 0.542µm - 0.99185229% to 0.991711641% 0.583µm - 0.990741324% to 0.990581773% 0.626µm - 0.989502842% to 0.989322296% 0.673µm - 0.988064051% to 0.987859217% 0.723µm - 0.98643681% to 0.986204642% An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 65 0.777µm - 0.984568763% to 0.984305388% 0.835µm - 0.98243597% to 0.982137196% 0.898µm - 0.979973117% to 0.979633766% 0.965µm - 0.977189524% to 0.976804703% 1.037µm - 0.97401279% to 0.973576582% 1.114µm - 0.970407324% to 0.969913447% 1.197µm - 0.96628576% to 0.965726809% 1.286µm - 0.961602624% to 0.960970834% 1.382µm - 0.956254985% to 0.95554145% 1.486µm - 0.950127578% to 0.949322255% 1.596µm - 0.943284553% to 0.942379086% 1.715µm - 0.935483037% to 0.934466443% 1.843µm - 0.926655369% to 0.92551694% 1.981µm - 0.916665386% to 0.91539408% 2.129µm - 0.905448926% to 0.904034751% 2.288µm - 0.892872292% to 0.891305872% 2.458µm - 0.878887406% to 0.877161548% 2.642µm - 0.863204774% to 0.861312453% 2.839µm - 0.845882646% to 0.843821592% 3.051µm - 0.826744956% to 0.824515928% 3.278µm - 0.805820108% to 0.803429546% 3.523µm - 0.782894245% to 0.780353191% 3.786µm - 0.758072302% to 0.755399484% 4.068µm - 0.731416689% to 0.728638393% 4.371µm - 0.702949063% to 0.700099229% 4.698µm - 0.672659913% to 0.669780483% 5.048µm - 0.640972475% to 0.638113293% An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 66 5.425µm - 0.607912669% to 0.605130293% 5.829µm - 0.573920826% to 0.571276556% 6.264µm - 0.539144865% to 0.536703771% 6.732µm - 0.50395228% to 0.501780342% 7.234µm - 0.468801479% to 0.466962016% 7.774µm - 0.433947122% to 0.432499956% 8.354µm - 0.399785014% to 0.398782705% 8.977µm - 0.366627053% to 0.366113513% 9.647µm - 0.334713183% to 0.334722954% 10.37µm - 0.304184977% to 0.304743759% 11.14µm - 0.275608331% to 0.276723831% 11.97µm - 0.248748461% to 0.250424883% 12.86µm - 0.223831065% to 0.226060399% 13.82µm - 0.200749875% to 0.203519277% 14.86µm - 0.179440549% to 0.18273234% Andersen: 0.85µm – 0.999913961% to 0.999955991% 1.6µm - 0.99971859% to 0.999856083% 2.7µm - 0.999229974% to 0.99960637% 4.0µm - 0.998344319% to 0.999154307% 5.85µm - 0.996514432% to 0.998222567% 7.0µm - 0.995044745% to 0.997476454% An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 67 ... air supply An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 20 Figure – Spirometry chamber and outlet An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing. .. studies23, 24 An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 13 Multiple clinical and non-clinical studies on the impact of various forms of surgical clothing and the use of body... suspended from the hook in the ceiling of the chamber An Analysis of Bioaerosol Emissions From Orthopaedic Surgical Clothing 29 2.4 Emission rate analysis The mean emission rate (ER) of particles and