Simulated Use Testing of Laparoscopic Instruments
Utilizing ATS
Target Devices
May use either or both ported laparoscopic devices and non-ported devices.
Both ported and non-ported devices should be thoroughly cleaned (recommended
with a retroflush device accompanied by sonication), packaged and steam
sterilized before simulated-use testing.
Inoculation
The inoculum consists of ATS soil that contains E. faecalis and G.
stearothermophilus at approximately 1 £ 106 cfu/mL. Soil laparoscopic
devices using a retro-flush adaptor to inject ATS upwards from the distal
end of the device until soil is seen exiting from either the handle or the
luer port at the handle. This ensures that the entire inner lumen is exposed
to soil and organisms. Allow the inoculated laparoscopic devices to sit at
room temperature for 1 hour before cleaning. Allow all excess soil to drain
out of the laparoscopic devices after the soiling stage. Include positive
controls (soiled, but un-cleaned) and negative controls (unsoiled, uncleaned)
in all experiments.
Methods for evaluating residual soil and organisms
To determine the level of residual organisms and soil, both indirect and
direct (in situ) test methods may be used. .
Sample collection for indirect quantitative testing
Take samples from the devices by attaching a sterile retro-flush adaptor to
the distal end of the laparoscopic device and use a sterile syringe to flush
10 mL of sterile reverse osmosis (RO) water up and down in the lumen for
three times prior to withdrawing the sample and placing it in a sterile
tube. Evaluate this sample quantitatively for protein, carbohydrate,
hemoglobin and viable counts by the methods previously described by Alfa and
Nemes.
In situ Bradford’s test for residual protein
Flush the laparoscopic device with air or held vertically to allow excess
fluid to drain. This is done to ensure that there is no residual fluid
and/or soil within the channel. Use a sterile retro-flush adaptor to instill
undiluted Bradford reagent (Sigma Chemical Co., St Louis, MO, USA) directly
into the lumen until it is full. Hold the device horizontally for 20 min at
room temperature to allow color development. Bradford reagent will turn blue
in the presence of protein. Drain the Bradford reagent after 20 min from the
device by using a separate sterile retro-flush adaptor and syringe connected
to the distal end to aspirate fluid from the lumen. Use a separate sterile
retro-flush adaptor for each device. Score the fluid visually for any
visible blue coloration and determine the absorbance by using a
spectrophotometer equipped with a 595 nm filter.
In situ TMB-one test for residual hemoglobin
Flush the laparoscopic device with air or hold it vertically to allow excess
fluid to drain. This is done to ensure that there is no residual fluid
and/or soil within the channel. Use a sterile retro-flush adaptor to instill
undiluted TMB-One reagent (Biotecx Laboratories, Houston, TX, USA) into the
lumen until it is full. Hold the device horizontally for 20 min at room
temperature to allow color development. TMB-One reagent will turn green in
the presence of hemoglobin. Drain the TMB-One reagent after 20 minutes from
the device by using a sterile retro-flush adaptor and sterile syringe
connected to the distal end to aspirate fluid from the lumen. Use a separate
sterile retro-flush adaptor for each device. Score the fluid visually for
any visible green coloration and determine the absorbance by a
spectrophotometer equipped with a 495 nm filter. TMB-One testing is to be
performed only on non-ported laparoscopic devices.
A study utilizing the above methods:
AJIC- American Journal of Infection Control - Volume 34
To determine if our soil challenge was realistic, clinical samples were
collected. Soil levels in patient-used laparoscopic accessory devices were
evaluated using the same sampling technique described in Materials and
methods. There was an average of 5560 mg/lumen protein, 1679 mg/lumen of
hemoglobin and 295 mg/lumen carbohydrate.
