1. health and fitness
2. disease

Progress of the German
working group for the cleaning
of DaVinci-instruments
Dr. Markus Wehrl
wfk – Cleaning Technology Institute e.V.
CSC Anual Scientific Meeting / April 14th 2015 / Chepstow
DaVinci®-System
Dual
Blade
Retractor
Black
Diamond
Micro
Forceps
Large Clip
Applier
DaVinci®
FDA clearance in 2000
DaVinci S®
DaVinci Si®
DaVinci Xi® introduced in summer 2014
Tenaculum
Forceps
ProGraspTM
Forceps
HotShears
TM
Mega
SutureCutTM
Needle Driver
Dissecting
forceps
EndoWrist
Stabilizer
Operated Robotic Systems
Europe
Canada 22
416
Direct
Germany 61
France 60
Belgium 30
UK 29
Switzerland
20
Netherlands
17
Sweden 15
USA
1,878
Brazil 7
Argentina
4
Chile 4
Venezuela
3
Mexico 3
Colombia 2
Panama 1
Uruguay 1
Latin
America
25
Saudi Arabia
11
Israel 6
Qatar 4
Pakistan 2
Egypt 1
Kuwait 1
Lebanon 1
Middle
East
26
Distribution
Italy 65
Spain 25
Turkey 16
Russia 14
Denmark 13
Norway 10
Czech
Republic 8
Finland 5
Austria 4
Ireland 3
Greece 8
Romania 6
Bulgaria 1
Slovakia 1
Poland 1
Portugal
1
Slovenia
1
Cyprus 1
Monaco
1
Asia
191
Japan 80
South Korea 36
China 22
India 21
Taiwan 14
Thailand 7
Singapore 5
Malaysia 4
Indonesia 1
Philippines 1
72 systems in 70 hospitals (Feb. 2014)
Australia
27
Robotic Instruments
Housing
Distal
Working End
Shaft
Maryland Bipolar Forceps
8 mm, 10 reproc. cycles
Shaft diameter: 5 or 8 mm
8 mm instruments are predominantly used
Number of reprocessing cycles: 10x to 25x depending on the type
Reprocessing in Germany…
Once in time (Spring 2011)….
…a hospital sent instruments of unknown status
under unknown conditions to a laboratory for
analyzing residual proteins….The lab applied
immunological (?) and nephelometric (?)
methods and found more albumin than total
protein…..
The lab had some “scientific problems” and the
hospital, too.
The results were reported to local authorities, these informed federal
authorities
Reprocessing of robotic instruments was interdicted
immediately.
Formation of the WG
Establishment of group: August 23rd 2012
AIM:
Establishment of a method for the reproducible assessment of cleaning
efficacy within process validation (PQ).
Two Publications
Wehrl M., Michels W., 2013
A method for testing the
cleaning of MIS robotic
instruments.
CentralService 2013(3): 202-207
Wehrl M., Albers G., Bühler K., Diedrich D., Frister H.,
Heintz M., Hubert H., Köhnlein J., Michels W.,
Rosenberg U., Roth K., Wallace B., 2014
Round robin tests conducted by the working group
DaVinci („AG DaVinci“) to establish a method for
testing the cleaning of MIS robotic instruments.
CentralService 2014(3): 173-179
Two Elution Methods
No. of applications/
reprocessing cycles:
0 < maximum No.
Type I
Non-destructive
testing
Elution of distal
working end and elution
of shaft interior
No. of applications/
reprocessing cycles:
Maximum No.
Type II
Destructive testing
Dismantling of distal working
end and elution
Dismantling of shaft element
and elution
Type I-Testing: Non-Destructive
The tip is eluted (upright position) using a vial
that is filled with 6 ml 1 % SDS-solution (pH=11)
Elution time: 30 min,
periodic movement of tip (4x)
Following this eluate is filled in flush port 1
to elute the interior of the shaft
Elution time: 30 min, periodic redrawing
and injection of the solution (4x)
Picture by Dr. W. Michels
Protein quantification:
mod. OPA- or BCA-method
Pre-Test: Recovery Rate
CORRECTED RECOVERY RATE [%]
100
Maryland Bipolar Forceps
soiling into the shaft element
100 µg, 250 µg, 500 µg and 1000
µg BSA
n=3 instruments
n=8 unsoiled control instruments
OPA
90
80
70
60
50
40
30
20
10
0
100
250
500
1000
AMOUNT OF SOILING (BSA) [µg]
Recovery Rates of the four experimental sets: 69.1 – 79.3 %
(corrected for false-positive)
Soiling of the Shaft: „Muzzle Loader“
• PTFE-capillary (inner diameter: 0.6mm) filled with approx. 2 µl blood
• Picture analysis: determination of the volume of loaded soil (capillary
previously calibrated)
• Injection of soil
• Residues in the capillary eluted and quantified using the OPA-method
Recovery Rate [%]
Round-Robin on Type I-Testing
160
OPA
140
BCA
120
BCA-SQ
Maryland Bipolar Forceps
reactivated sheep blood
~2 µl into the shaft
~2µl onto the tip
n=3 instruments per lab
OPA / BCA
100
80
60
40
20
0
A
B
C
D
E
F
Lab
Mean Recovery Rate: 95.5 ± 20.5 % (not corrected for false-positives)
Type II-Testing: Destructive
The cap of the housing is dismounted, the bowden
cables are cut and the tip is dismantled. Bowden cables
and electric cables are cut at the crimping site on the
hypotube.
The distal working end is
eluted in a vial with
3 ml 1 % SDS (pH=11)
Elution: 30 min,
periodically vortexed (4x)
The ends of the shaft (containing
the Bowden cables) are closed, 4
ml 1 % SDS (pH=11) are injected
Elution: 30 min,
periodically vortexed (4x)
Protein quantification:
mod. OPA- or BCA-method
Recovery Rate [%]
Round-Robin on Type II-Testing
DW-OPA
160
140
120
100
80
60
40
20
0
SE-OPA
DW-BCA
SE-BCA
A
B
C
D
E
F
Lab
It was unsure, where the 2 x 2 µl of blood had been
deposited in the shaft. At the silicone gasket or at
parts that were analysed with the shaft element?
G
Maryland Bipolar Forceps
Reactivated sheep blood
2µl onto the tip
2 µl into the shaft at the
silicone gasket
2 µl into the shaft approx.
15 cm above the distal
working part
n=3 instruments per lab
Round-Robin on Type II-Testing
Recovery Rate [%]
Residues of tip and shaft element were added
160
140
120
100
80
60
40
20
0
OPA
BCA
A
B
C
D
E
F
G
Lab
Mean Recovery Rate: 83.1 ± 16.6 % (not corrected for false-positives)
Analysis of Eluates
Prerequisite: Eluates must not be turbid.
If turbid  rejected
Suitable methods for protein quantification:
• Modified ortho-Phthaldialdehyd (OPA)-method (EN ISO 15883-1)
• Bicinchoninic acid (BCA)-method (EN ISO 15883-1)
• e.g. INTERCHIM BC Assay Protein Quantification Kit
• e.g. QuantiPro BCA Assay Kit
• e.g. Miele-test kit using the reflectometer Rqflex plus 10 Reflectoquant
(Merck, Germany)
Interfering Substances
• OPA and BCA exhibit an interference with substances released from the
instruments
• New instruments reprocessed 5x exhibited a false-positive protein
content of 48.8 ± 5.60 µg
• After >20 reprocessing cycles interfering substances were present to
strongly varying amounts (5 – 50 µg)
• Interfering substances could not be identified. One strongly interfering
component is tungsten from the bowden cables
• Extraction of interfering substances using chloroform, cyclic hexane,
ethyl acetate, xylol failed
• Protein cleaning columns failed, they gave a protein loss of approx. 50 %
but no removal of interfering substances
Interfering Substances
• Corrosive (H2O2) or highly alkaline reprocessing chemicals are suspected
to increase the problem of interfering substances
NO SYSTEMATIC ERROR
NO CORRECTION POSSIBLE
Assumption made in the group:
Protein quantification is NOT corrected for false-positive interference.
It is assumed that false-positive interference and the recovery rate below
100 % are compensating each other partially.
Acceptance Criteria
• All outer surfaces of the instruments must be visually clean
• The residual protein content is judged on the basis of the
“surface-related protein-content”: 3 µg/cm2
• ISO TC 198 WG13: discussing 2 – 6.4 µg/cm2
• 3 µg/cm2 applied by the German guideline for the validation of manual
reprocessing procedures (DGKH, DGSV, AKI and VAH), October 2013
• 3 µg/cm2 applied by the German guideline for the validation of
automated reprocessing procedures for thermo-stabile instruments
(DGKH, DGSV, AKI), revised October 2013
Surface
Only relevant surfaces (patient contact, soiled) are considered
Maryland Bipolar Forceps, MBF, Intuitive Surgical Inc., USA
Area
Distal Working Part: inner and outer surfaces of metal part,
including 2 cm bowden cables/cables
27 cm2
Shaft Inner Surface: Length 42.5 cm, including cables,
hypotubes, flush tube
266 cm2
Relevant part of Shaft Element: 6 cm of distal part of shaft,
including Bowden cables/cables, 1.5 cm of flush tube
24 cm2
Acceptance Criteria
Using the 3 µg/cm2 acceptance value
• Type I-Testing: 155 µg
• Type II-Testing: - Distal Working Part: 80 µg
- Inner of Shaft Element: 75 µg
The proposed maximum values were not
well received by federal authorities like
BfArM, as the Guideline of the RobertKoch-Institute (RKI) postulates a
maximum of 100 µg/instrument.
Conclusion
Standardized and specified methods were established.
Recovery rates and reproducibility were shown to be fair and acceptable
with regard to the complexity of the instruments.
The method is accepted by federal authorities like BfArM (Federal
institute for pharmaceuticals and medical devices, Bonn)
Federal authorities recognized that interfering substances might
influence residual protein quantification but do not pose a hazard to
patient safety as supported by data from different cytotoxicity studies.
Conclusion
Residues in the housing are no problem with regard to patient safety
Colored areas in the housing resulted from wear of friction, corrosion
and precipitates from water and are not critical with regard to hygiene
It was recognized by BfArM, that DaVinci instruments can be
reprocessed in general
Hospitals that had experienced interdiction of reprocessing DaVinciinstruments are back to normal reprocessing operation.
Outlook
The working group currently sets up a “field-investigation”:
5-10 hospitals are invited to apply the methods and to share results.
Aim is to obtain a pool of results from at least 100 tested instruments
Alternative methods for the rapid assessment of cleanliness will be
tested and compared
Results will give information about:
- the applicability of the methods in hospitals
- average values for residual protein content
Results of the “field-test” will be published
If you are interested in…..
…..reprocessing of complex medical devices and
beyond….
…..actual developments in cleaning, disinfection,
sterilization….
…..guidelines, working groups and beyond……
then join us at:
“Colloquium Medical Instruments”
May 21st 2015
Hilton Conference Center
Düsseldorf
(conference language DE/EN)
www.wfk.de
Thank you very much…..
….for your interest and
attention
Dr. Markus Wehrl
wfk – Cleaning Technology Institute e.V.
Campus Fichtenhain 11
47807 Krefeld
Germany
++49-2151-8210-170
m.wehrl@wfk.de
About the speaker
• Born 1974
• 1995-2001 Studies in biology and PhD at the
Research Center for Infectious Diseases of
the University Würzburg, Germany
• Since 2006 with wfk, since 2011 head of the
Dept. of Hygiene and Microbiology
• Focus: - thermo-labile MD/implants
- low-temp sterilization procedures
- supercritical CO2 processes
• Activities: - coordinator for DGKH e.V. of the guideline on thermo-labile
endoscope reprocessing
- WG “Performance testing of instrument cleaners” of DGKH e.V.
- WG „AG DaVinci“ on robotic instruments
- ISO/TC94/SC13/WG6 on surgical textiles
The speaker-private
Hobbies:
- Amateur Radio at frequencies above 50 GHz
- Growing of carnivorous plants (Drosera sp.)