wfhss and das conference 2013 - session a-3: potential ......wfhss and das conference 2013 - session...
TRANSCRIPT
Potential of Cold Atmospheric Plasma as a new method for the decontamination and
sterilization of reusable surgical instruments.
14th World Sterilization Congress8th National Sterilization Disinfection Congress of Turkey
6th-9th November 2013
Rodolphe Hervé PhD, MSc
The five main functions performed in a hospital sterile service department
Standard reprocessing
Decontamination and sterilization
Assessment of instruments cleanliness
a
d
b c
e f
Thioflavin T (bright blue) and SYPRO Ruby (amber) dual staining observed on (a-e) a suction canullae and (f) diathermy forceps from a neurosurgery set that were fully reprocessed through a sterile service department. White bars are 100 μm, red bar is 10 μm.
Standard reprocessing: neurosurgery instruments
Hervé et al., JHI 2010
Proteinaceous (total and amyloid) contamination on a succion cannulae isolated from a craniotomy set.
Standard reprocessing: neurosurgery instruments
Standard reprocessing: flexible luminal endoscopes
Hervé et al., JHI 2012
Standard reprocessing: endodontic files
Standard reprocessing: endodontic files
0
50
100
150
200
250
300
350
400
ng/m
m2
0
2
4
6
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10
12
Control Cleaner 1 Cleaner 2 Cleaner 3 Cleaner 4
Treatment
ng/m
m2
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Hervé et al., JHI 2010
Cleaning limitationsProtein removal action of various cleaners
Cleaning limitations
0
10
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60
70
Control Cleaner 1 Cleaner 2 Cleaner 3 Cleaner 4
Treatment
Am
yloi
d / P
rote
in ra
tion
(%)
++
++
Remaining contamination on surfaces(proportion of hydrophobic amyloid-rich proteins)
Hervé et al., JHI 2010
Mechanism
Physical disruption (detergent, sonication, brushing, flushing)
Enzymatic degradation
Chemical modification (pH>12)
Potential caveats
Displacement and/or spreading
Shelf life; control of parameters
Damage to instruments; control of parameters and efficacy
How can standard cleaning fail ?
What is gas plasma?
BenefitsBenefits
• Energetic electrons à chemical dissociation @ low gas temperature
• On-site production of reactive, short-living species e.g. O2
•–; O; 1O2; NO … OH• and H2O2à known to act
on protein, lipid and DNA
• Oxidants: OH•, O2•–; O; 1O2, H2O2
Non-equilibrium Chemistry
Kong MG et al (2009) New J. Phys. 11: 115012; Iza F et al (2008) Plasma Process. Polym. 5(4): 32.
what is gas plasma?| Shooting Plasma
Nan
osec
ond
imag
ing
Exposure: 1nsInterval: 100 ns
CAP endo-decon| Electron Bombardment
Walsh JL and Kong MG (2008) Appl. Phys. Lett. 94: 021501;
Testing of first CAP prototype
High purity helium/oxygen mix
CAP parameters during initial tests
5 L/min and 100 ml/min respectively
Target surface set within 1.5 cm
Up to 2 min application
0
0.005
0.01
0.015
0.02
0.025
0.03
reference 30 sec 60 sec 90 sec 2 min 2+1 min 2+2 min
Treatment duration
Rem
aini
ng c
onta
min
atio
n (μ
g/m
m 2 )
Testing of first CAP prototype
Spiked implant wires before CAP treatment
Spiked implant wires after partial CAP treatment
CAP appears equally effective againstamyloid proteins
05000
1000015000200002500030000350004000045000
control CAP-treated
Res
idua
l con
tam
inat
ion
(pix
els
per f
ield
of v
iew
)
0
0.5
1
1.5
2
2.5
3
3.5am
yloid / total protein ratio (%)
Total protein Prion amyloid amyloid proportion (%)
CAP endoDecon| Versatility and Uniformity Control
Cao Z et al (2009) Appl. Phys. Lett. 94: 021501; Nie Q et al (2009) New J. Phys. 11: 115015; Kong MG (2011) J. Phys. D: Appl. Phys. 44(17): 174018; Walsh JL et al (2008) IEEE Trans. Plasma Sci. 36(4): 1314.
CAP
The place of CAP in standard reprocessing
CAP
The place of CAP in standard reprocessing
CAP
The place of CAP in standard reprocessing
Dentistry clinics; Endoscopy Units
what is gas plasma?| OptimisationAr-O2-H2O Plasmas
• up to 1,000 chemical reactions• threshold dose of each protein-inactivating plasma agent is unknown
• complication with synergy• plasma diagnostics is complex and not always accessible
• plasma diagnostics in liquid phase – very under-studied field• if achieved, a knowledge-based inaction – indirect inactivation marker
• … empirical strategy – unreliable for ensuring efficacy and for system scalingAgents Plasma Characterisation
O*; OH* etc Excited species – Optical emission spectroscopy(OES)
O, H2O-clusters Ground state – OES not good – MBMS
OH, H2O2 etc in H2O Electron spin resonance (ESR) spectroscopy
UV Absolute OES
Ozone Spatial resolved – UV absorption spectroscopy (UVAS)
Electron density Probes not applicable – current density
Electron energy Boltzmann plot
All Plasma modelling
… additional studies, such as OH scavengers
CAP optimisation
EDIC/EF for rapid and very sensitive quantification of residual proteins and microorganisms.
Refined prion infectivity assays for human strains under development.
Mechanisation and scaling up of the process.
Adaptation into SSDs.
Proteinaceous microcontamination (potentially including PrPSc in affected countries) is a common problem in clinical settings.
Conclusions
Current standard decontamination procedures suffer from inherent physicochemical limitations.
CAP offers a radically different decontamination mechanism capable of targeting individual atoms, without the problems associated with liquid solutions.
Further development required to adapt the technology to different end users/instruments.
SSDs (England)
Acknowledgements
English Department of Health
The Pirbright Institute
NCJDSU (Edinburgh)
CEA (France)
Public Health England
Fondation Alliance BioSecure
