DECONTAMINATION
(where these microorganisms can evade disinfection) and can also significantly impact the device function. In addition, computer screens, especially the more common touchscreens, can be significantly affected by products that contain more concentrated alcohol and ammonia.
Some thermoplastic products (e.g.,
acrylics and PVC) can be impacted more than thermosetting materials (e.g., epoxy). In addition, some of the cleaning solutions and disinfection formulas contain extra ingredients, such as fragrances, humectants, and preservatives, which can increase the probability of causing damage to certain types of plastics, potentially leading to unexpected cracking and part failure in these components. Therefore, it is very important during the early phase of medical device development to evaluate the stability of that material to that disinfectant, or its operation in a particular fluid. For example, does it swell, does it take up the fluid in any way, does it react chemically and does that affect the performance of the material? The cleaning process must not chemically destabilise the material and add more stress to it. Therefore, chemicals that cause ESC7 can be divided into those that swell or wet the plastic/polymer and those that chemically react with the substrate. An example of the latter would be the caustic or aqueous sodium hydroxide that can hydrolyse polyethylene terephthalate (PET). Crazing is associated with the reduction in plastics’ molecular weight due to hydrolysis, which can result in device failure over time. The period of exposure to cleaning solutions is often relatively short. However, the combination of constant use, increased stress levels, and the ability of chemical compounds in cleaning solutions to diffuse into, and remain inside, plastic parts may promote ESC long after use, compromising the service life of the product.
Solvents8 that result in stress cracking
of most polymers include petroleum ether, carbon tetrachloride, toluene, acetone and ethanol. Also, the most common isopropyl alcohol has been associated with cracking and breaking of some plastics. Fluids that are absorbed by a plastic in a short period of time under simple immersion conditions have a high probability of being severe stress cracking agents for that particular plastic. Such liquid/plastic interactions can be evaluated using chemical and material compatibility tests.
These interactions should be avoided during the design phase by appropriate testing and polymer selection. It has been reported that liquids with weak hydrogen bonding are usually strong or moderate stress cracking agents. These include organic liquids such as aromatic
SEPTEMBER 2021
hydrocarbons, halogenated hydrocarbons (chlorine, fluorine), ethers, ketones (acetone), aldehydes (formaldehyde), esters, and nitrogen and sulphur containing compounds (quaternary ammonium compounds). These chemicals such as isopropyl alcohol, ethanol, formaldehyde, chlorine, quaternary ammonium compounds and acetone are used widely in healthcare settings as disinfectants for surfaces, equipment, medical tools, medical devices and other objects.
Statistics and recalls of failed medical devices The MHRA and Health Facilities Scotland9 have received reports for medical device alerts regarding detergent and disinfectant wipes that have damaged plastic surfaces of these devices and significantly impacted their function. The reports describe damages to devices such as tympanic thermometers,
patient monitors, infusion pumps, dialysis fluid filters, peritoneal dialysis transfer sets and infant warmers as a result of using detergent wipes that contain incompatible chemicals. In addition, a search of the FDA’s medical device recalls indicates the phenomenon of medical device failures is not new. For example, a haemodialysis instrument10
was
was recalled in 2006 because
polymer parts may become cracked due to chemical, mechanical or thermal stress. Moreover, in 2009, a surgical light11
recalled because cracks could form around the screw connections of the cover plates making them easier to break and crack, leading to fragments breaking off and falling into the operating space. Investigations have shown that the cracking is significantly influenced by the use of certain cleaning solutions containing alcohol. The operator manual previously stated to avoid using
VIO®
3 plug and operate
Electrosurgery
Handling of the VIO 3 with stepGUIDE, the new modes, and the highest level of flexibility in the selection of instruments, all make for maximum ease of use.
with maximum convenience
Then there are the other advantages: ☑ Reliably reproducible tissue effects thanks to state-of-the-art processor technology ☑ Selection of up to 6 different settings for your procedure from the operating field ☑ Use of up to 6 instruments ☑ Large touchscreen display
Erbe Medical UK Ltd Leeds United Kingdom +44 113 253 0333
erbe-uk.com
AZ_Erbe_VIO_3_210x297_0217.indd 1
03.07.2017 13:18:24
WWW.CLINICALSERVICESJOURNAL.COM l 41
▲
© Erbe Elektromedizin GmbH 2017
2017-02
D119931
non-US only
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88
