REPROCESSING LAPAROSCOPY USING LOW TEMPERATURE STERILIZATION…VH2O2 or LTSF?
Comparison in terms of gentleness & ease of use with medical devices
Authors: Dr. Daniel Vázquez1; Dr. Nelson Carreras2; Dr. Alex Zamora3; Ing. Alejandro Ramírez4. 1Matachana Test Center Coordinator, 2Global Product Manager Consumables, 3RDI Chemist, 4Global Product Manager Low Temperature Sterilizers. Abbreviations: VH202 – Vaporized Hydrogen Peroxide, LTSF – Low Temperature Steam and Formaldehyde, RMD – Reprocessable Medical Device, PCD – Process Challenge Device
WFHSS-GUIDELINES
According to WFHSS-Guidelines “heat sensitive RMD’s require a range of cycles adapted to their material and geometrical specificities. Some heat compatible, minimally invasive surgery instruments are subject to accelerated aging (e.g., laparoscopy devices). Some countries offer the flexibility to use low temperature sterilization; other countries do not”. [1]
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BUT IF WE DECIDE TO TERMINALLY STERILIZE LAPAROSCOPY DEVICES USING A LOW TEMPERATURE METHOD, WHICH IS THE GENTLEST TECHNOLOGY WITH THE MEDICAL DEVICES? VH2O2 OR LTSF? |
THE EFFECT OF FORMALDEHYDE AGAINST MICROBIAL PROTEIN
In solution, formaldehyde can be found in various forms, bounded to water molecules. We can find monomeric (monohydrate) species known as methylene glycols and polymeric (polyhydrated) species named polyoxymethylene glycols in the formaldehyde solution. At room temperature and low concentrations, the monomer/polymer solution ratio is 1:1200, in accordance with data from various studies. [2-6]
In addition, polyoxymethylenes can consist of various numbers of glycol groups:
- CH2O – formaldehyde
- CH2(OH)2 – methylene glycol, formed by adding a water molecule
- (CH2O)3 – trioxymethylene glycol or paraformaldehyde
- (CH2O)n – different polyoxymethylene glycols
These polymeric species can polymerize to form a white precipitate depending on temperature and concentration. In the e-bag® solution, ethanol serves to stabilize formaldehyde and prevent its polymerization, thereby avoiding the formation of precipitates. [7-9]
Formaldehyde is stable in its gaseous state, and its biocidal activity originates from its ability to interact with amino groups from proteins and nucleic acids, as illustrated in Figure 1. Its carboxyl group is highly reactive and interacts with proteins and nucleic acids, conferring it broad-spectrum effectiveness against microorganisms. [10]
Microbicidal mechanism:
Formaldehyde’s aldehyde group cross-links membrane proteins, denaturing them and also damages DNA and RNA, disrupting cellular function and leading to microorganism death. [11-12]
Figure 1. Cross link and formation of methylene bridges by formaldehyde between (A) proteins and (B) proteins and nucleic acids. [17]
THE EFFECT OF VH2O2 AGAINST MICROORGANISMS
Vaporized Hydrogen Peroxide (VH2O2) is a highly oxidizing substance and its active derivatives produced after decomposition have strong oxidation effects which directly disrupt the cell cytomembranes of microorganisms. However, this powerful oxidative action can also impact the materials used in medical devices, potentially leading to issues such as corrosion or gradual material degradation over time. [13]
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WE’VE SEEN THAN LTSF IS THE GENTLEST TECHNOLOGY, BUT WHICH IS THE EASIEST TECHNOLOGY TO OPERATE? |
Loading the sterilizer is a crucial step during the terminal sterilization process. After washing, inspecting, assembling (if required), drying and packing/pouching the laparoscopic devices, we’ll need to properly load the sterilizer according to the specification of the sterilization program selected. Proper loading process following the sterilizer’s Instructions For Use, will ensure that after selecting the load-related sterilization program, the sterilization conditions on the load will be achieved.
In this regards, VH2O2 sterilizers are known for their complexity during the loading chamber process. In general, the maximum length and minimum internal diameter of each medical device, as well as the total number of devices with lumen should be checked. [14-16] But not only, as in all terminal sterilization modalities, also the total load weight should be controlled. [14-16] The different combinations of these loading requirements play a crucial role to achieve sterilization, as if any of them is not fulfilled there is no sterilization warranty in the complete load. This is an extra stress factor to the operator.
THE EASE OF LOAD – Low Temperature Steam & Formaldehyde
On the other hand, Low Temperature Steam and Formaldehyde technology offers excellent penetrability performance, thanks to the use of steam to transport the sterilant into the narrow lumens and the high stability of the formaldehyde molecule. This allows the technology to require simple loading specifications; only the total load weight should be confirmed.
The following table shows penetrability tests results from Matachana Test Center using biological indicators according to ISO 11138-5, inside a process challenge device (PCD) receptacle with different lumen lengths and inner diameters.
Table 1. Sterilization efficacy comparison between VH2O2 and LTSF technologies in stainless steel lumens.
|
Inner Æ |
Length |
LTSF Sterilization |
VH2O2 Sterilization |
|
0,5 |
500 |
Pass |
Fail |
|
1000 |
Fail |
Fail |
|
|
0,7 |
500 |
Pass |
Pass |
|
1000 |
Pass |
Pass |
|
|
2000 |
Pass |
Fail |
Table 1 confirms the highest penetrability performance compared to VH2O2 sterilizers, which typically are not compatible with rigid lumens below 0.7 mm inner diameter and longer than 500 mm. [14] In any case, some manufacturers[16] claim 0.48 mm inner diameter with length no longer than 100 mm, but always limiting the number of lumens up to 20.
CONCLUSIONS
In conclusion, LTSF sterilization process is gentler with materials compared to other low temperature technologies, as its microbicidal effect, rooted in denaturalizing proteins rather than oxidation, minimizes damage to materials.
- Sterilization Efficacy: Both LTSF and VH2O2 provide high sterilization efficacy, yet their mechanisms differ significantly.
- Material Compatibility: LTSF distinguishes itself for its gentle treatment of materials, particularly sensitive instruments, due to its protein denaturation mechanism, contrasting with VH2O2’s potential long-term oxidative impact on materials.
- Operational Ease: LTSF technology offers operational simplicity, requiring only adherence to total weight requirements during the loading process.
Choosing between these technologies depends on factors such as device materials, facility protocols, and regulatory compliance. Understanding these nuances ensures optimal sterilization outcomes while maintaining the integrity of medical instruments.
BIBLIOGRAPHY
1 Reusable medical device – Wfhss Guidelines. (n.d.). Retrieved June 20, 2024, from https://wfhss-guidelines.com/reusable-medical-device/
2 Rivlin, M., Eliav, U., & Navon, G. (2015). NMR studies of the equilibria and reaction rates in aqueous solutions of formaldehyde. Journal of Physical Chemistry B, 119(12), 4479–4487. https://doi.org/10.1021/JP513020Y
3 Gold, A., Utterback, D. F., & Millington, D. S. (1984). Quantitative Analysis of Gas-Phase Formaldehyde Molecular Species at Equilibrium with Formalin Solution. Analytical Chemistry, 56(14), 2879–2882. https://doi.org/10.1021/AC00278A058
4 Winkelman, J. G. M., Ottens, M., & Beenackers, A. A. C. M. (2000). The kinetics of the dehydration of methylene glycol. In Chemical Engineering Science (Vol. 55, Issue 11). PERGAMON-ELSEVIER SCIENCE LTD. https://research.rug.nl/en/publications/the-kinetics-of-the-dehydration-of-methylene-glycol
5 Winkelman, J. G. M., Voorwinde, O. K., Ottens, M., Beenackers, A. A. C. M., & Janssen, L. P. B. M. (2002). Kinetics and chemical equilibrium of the hydration of formaldehyde. Chemical Engineering Science, 57(19), 4067–4076. https://doi.org/10.1016/S0009-2509(02)00358-5
6 Matubayasi, N., Morooka, S., Nakahara, M., & Takahashi, H. (2007). Chemical equilibrium of formaldehyde and methanediol in hot water: Free-energy analysis of the solvent effect. Journal of Molecular Liquids, 134(1–3), 58–63. https://doi.org/10.1016/J.MOLLIQ.2006.12.002
7 Kent, D. R., Widicus, S. L., Blake, G. A., Goddard, W. A., & Iii, W. A. G. (2003). A theoretical study of the conversion of gas phase methanediol to formaldehyde A theoretical study of the conversion of gas phase methanediol to formaldehyde. J. Chem. Phys, 119, 5117–5120. https://doi.org/10.1063/1.1596392
8 Kleimeier, C. F., Turner, N. F., Singh, A. M., Fortenberry, S. K., & Kaiser, R. C. (2022). Synthesis of methanediol [CH 2 (Oh) 2 ]: The simplest geminal diol. Proceedings of the National Academy of Sciences, 119(1), 2111938119. https://doi.org/10.1073/pnas.2111938119
9 Lilienblum, W. (2012). Opinion of the Scientific Committee on Consumer Safety on methylene glycol; Opinion of the Scientific Committee on Consumer Safety on methylene glycol. https://doi.org/10.2772/83316
10 World Health Organization. (2016). Decontamination and Reprocessing of Medical Devices for Health-care Facilities. http://www.who.int
11 Mcdonnell, G., Russell, A. D., Operations, L., & Louis, S. (1999). Antiseptics and Disinfectants: Activity, Action, and Resistance. CLINICAL MICROBIOLOGY REVIEWS, 12(1), 147–179.
12 Loshon, C. A., Genest, P. C., Setlow, B., & Setlow, P. (1999). Formaldehyde kills spores of Bacillus subtilis by DNA damage and small, acid-soluble spore proteins of the alpha/beta-type protect spores against this DNA damage. Journal of Applied Microbiology, 87(1), 8–14. https://doi.org/10.1046/J.1365-2672.1999.00783.X
13 Tao, M., Ao, T., Mao, X., Yan, X., Javed, R., Hou, W., Wang, Y., Sun, C., Lin, S., Yu, T., & Ao, Q. (2021). Sterilization and disinfection methods for decellularized matrix materials: Review, consideration and proposal. Bioactive Materials, 6(9), 2927. https://doi.org/10.1016/J.BIOACTMAT.2021.02.010
14 STERRAD User’s Guide REF A11150401. ASP. Retrieved June 20, 2024, from https://eifu.asp.com/
15 STERRADTM Low temperature sterilization. ASP. Retrieved June 20, 2024, from https://www.asp.com/low-temp-esterilization
16 STERIS Instructions For Use | Operator Manual. STERIS. EN 10085896 Revision H. Retrieved June 20, 2024, from https://www.steris.com/healthcare/instructions-for-use
17 Adapted from “Kouchmeshky, A., & McCaffery, P. (2020). Use of fixatives for immunohistochemistry and their application for detection of retinoic acid synthesizing enzymes in the central nervous system. Methods in Enzymology, 637, 119–150. https://doi.org/10.1016/BS.MIE.2020.03.010” with BioRender.com
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