INHERENTLY SAFE DESIGN OF A PRACTICABLE MEDICAL LASER HANDPIECE - PowerPoint PPT Presentation

INHERENTLY SAFE DESIGN OF A PRACTICABLE MEDICAL LASER HANDPIECE Lewis C. R. Jones 1 , Mark Parry 1 , John R. Tyrer 1 , Jason Britton 2 1 Loughborough University. 2 Leeds General Infirmary 24.5 th Laser Safety Forum 2020

Contents The rationale for a new design • Growing concerns with surgical smoke; Key findings from the literature • Legal movement in USA Experimental testing • Our approach to inherently safe design • Testing of design concept • Identification of surgical smoke hazards • Integrated handpiece optical filters and extraction The rationale for a new design • Design proposal • Conclusions and Further work 2

Laser Generated Surgical Smoke Recognition of the hazard • Surgical smoke is linked to respiratory irritation, the transmission of infectious and cancer cells, and genotoxicity [1–7]. • Cases of laser-generated surgical smoke causing infection in a surgeon [8] and a nurse [9]. • One gram of laser-generated surgical smoke contains 40 mg of smoke condensates, with an equivalent mutagenic potential of 3 cigarettes [10]. Recommended Risk Management • No specific legal requirement in UK using smoke evacuation [11]. Medical and Healthcare Products Regulatory Agency (MHRA) recommends to use masks and Local Exhaust Ventilation (LEV) [12] to meet the Control of Substances Hazardous to Health Regulations (COSHH) (SI 2002/2677) requirements. • The recommendations from research on risk control for surgical smoke includes the use of LEV and surgical masks [1–4,7,13–15] Changing legal position in USA The state of Rhode Island has effective, from January 1 st 2019, legislation • (RI Gen L § 23-17-49.1 2018) requiring action for surgical smoke. • Colorado has passed legislation (Colo. Rev. Stat. § 25-3-120 2019) that will become effective May 1 st 2021, • The states of New Jersey, Oregon, Utah, Kentucky, Georgia, and Tennessee have bills under various stages of review. 3

Current Risk Management Our ‘generic’ example a) b) Handheld extraction Laser fibre, control, nozzle and cryogen umbilical Local Exhaust Laser handpiece Ventilation Unit The underlying problem • Current LEV systems are highly reliant on the operator, policies and administrative procedures [4,16]. • Collection nozzle is very sensitive to position [17]. Use varies: 1. 47% (n = 1315) of laser surgeries used LEV, and 31% of procedures never used LEV [6]. 2. 66% (n = 50) of plastic surgery theatres had specialised smoke extractors [13]. 3. 43% (n = 67) of surgical consultants used smoke evacuators [18]. 4

Inherently safe design Most Effective Elimination Substitution Engineering controls Administrative controls PPE Least Effective 5

Engineering Controls Extraction tip provides focal standoff Tip seals to skin and Endoscope camera magnifying target image makes electrical contact Existing laser handpiece body, for safety interlock fibre delivery and focusing optics Air flow in clears smoke Integrated Extraction Out to filter Annular flow of extraction from source 6

Method Fibre delivery Stationary fibre support Biolitec diode laser Removable handpiece extraction Integrated Extraction Air flow in Sample height measurement 150mm 30mm TSI 3330 Optical External Extraction Particle Sizer Porcine skin sample Plume sample hose External Extraction Face Velocity Volumetric Flow Face Velocity Condition Measurement (m/s) Rate (L/min) Conversion (ft/min) Low 2.1 419 414 Medium 5 996 985 High 13.2 2629 2599 7

Results 4000 ← PM2.5 3000 Total particle count 2000 1000 0 0.300 - 0.374 0.374 - 0.465 0.465 - 0.579 0.579 - 0.721 0.721 - 0.897 0.897 - 1.117 1.117 - 1.391 1.391 - 1.732 1.732 - 2.156 2.156 - 2.685 2.685 - 3.343 3.343 - 4.162 4.162 - 5.182 5.182 - 6.451 6.451 - 8.031 8.031 - 10.00 Optical Particle Size - Sample Collection Channels (µm) PM2.5 is associated to an increase in daily mortality [19,20] and linked to pulmonary diseases [14,15]. The World Health Organisation (WHO) annual mean exposure guidelines for PM2.5 is 10 µg/m 3 [21]. 8

60 Peak concentration + Background from laser Background (M ± 1SD) 50 Laser with No Extraction (±5% Error) PM 2.5 Concetration (µg/m3) 40 Pre-sample collection time 30 Residual unextracted particulate generated by test 20 End of Laser Start of Laser sequence sequence 10 0 -40 -20 0 20 40 60 80 100 120 140 Time (s) 9

60 50 PM 2.5 Concetration (µg/m 3 ) 40 30 20 10 0 0 5 10 15 20 25 30 Time (s) 10

Design Proposal 11

Conclusions and Further Work • Peak PM =2.5 concentrations without 55.86 ± 2.79 µg/m 3 extraction 47.07 ± 2.35 µg/m 3 . • 16% reduction with typical extraction 2.19 ± 0.68 µg/m 3 • With device – only safe background reading • Identified reduction in respirable hazard of PM2.5 but it is know that surgical smoke has unique toxicology and infection risk. [8,10,22–24]. • Method to ensure safety through engineering controls. • Potentially eliminated both fume and radiation hazards to staff 12

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