LOW-TEMPERATURE STERILIZATION AND NEW TECHNOLOGIES

Nuevos métodos de esterilización a baja temperatura son una alternativa frente al óxido de etileno. El artículo tiene por objetivo identificar evidencias de actividad antimicrobiana, toxicidad, efectos colaterales y la aplicación de tecnologías por bajas temperaturas. La investigación fue realizada mediante consulta en los bancos de datos MEDLINE y LILACS hasta 2005. Fueron analizados en su totalidad 10 artículos, cuyos resultados demostraron que: a) los estudios sobre la eficacia de la esterilización se constituyen en investigaciones básicas y comparativas que muestran la influencia de la extensión y diámetro del lumen y la presencia de sales de cristal, b) la selección del equipo es tan fundamental como el garantizar la limpieza de los materiales que influyen en la eficacia de los procesos y en la toxicidad, c) la esterilización a bajas temperaturas muestra limitaciones para el caso de esterilización de injerto óseo, así como deteriora las propiedades de los materiales.

In our context, the search for new low temperature sterilization technologies is justified by the same motives as in the USA, besides the need for faster reprocessing than when using ethylene oxide.
The challenge for hospital infection control and material center professionals in health institutions is to assess available new technologies in terms of microbiological safety, cost-effectiveness and the absence of adverse effects for patients and professionals.Thus, the user's choice should be based on scientific evidence.
This bibliographic review aims to identify, in scientific literature, evidences of antimicrobial activity, toxicity, adverse effects and applicability of low temperature sterilization technologies.
However, no controlled keywords were located for: esterilização baixa temperatura/low temperature sterilization; plasma de peróxido de hidrogênio/ hydrogen peroxide plasma, which were used in the search as free keywords.

RESULTS
Table 1 presents the results obtained through the application of the described search strategy.The abstracts of all publications located in the databases were read, except for the results of the exclusive search with the descriptor sterilization, due to the large number of publications found and the lack of specificity.The abstracts were analyzed and those that addressed at least one of the following items were selected: antimicrobial activity, toxicity, adverse events and applicability of low temperature sterilization technologies.Only ten publications from the research universe complied with the inclusion criteria.
In the adopted search system, only one Brazilian study was located which did not attend to the inclusion criterion, as it presented the methodology for validating the low temperature formaldehyde sterilization technology.
Next, we will present a synthesis of the publications, according to the theme and the chronological order of publication.ETO showed the best performance, reaching the secure sterility level (3) .
Another study from 1998 assess the sterilization efficacy of four low temperature sterilization technologies: ETO, containing hydrochlorofluorocarbons (ETO-HCFC), STERIS® system, containing peracetic acid and hydrogen peroxide, and the Sterrad 100® and 100S® system, containing hydrogen peroxide plasma, 40-centimeterlong materials and lumens with a diameter of 1-3mm.
Narrower lumens compromised the efficacy of the sterilization processes by the Sterrad 100® and STERIS® systems, while the other methods displayed satisfactory results (4) .
Another publication from 1998 assessed the STERIS® system, 100% ETO and ETO-HCFC, for materials of 125cm and lumens with a diameter of 3mm.Differently from the results of the above study, the STERIS® system was significantly more efficient in comparison with the other processes to reduce the microbial load, although it did not achieve sterility.It should be observed that, in this situation, the material was longer, but with a less narrow lumen (5) .
The comparative analysis of these studies is limited by the fact that each of them presents different challenges to assess the performance of these technologies in terms of sterilization efficacy.formaldehyde sterilization takes three times longer than plasma, but, in comparison with ETO, the time was shorter, which implies lower costs.However, a larger inventory was needed.Vapor was considered the fastest and cheapest method and was chosen for small and medium-sized institutions, although it causes greater damage to instruments in the long term (8) .
Application: reuse of electrophysiology catheters - were not realized with catheters from all commercially available brands (9) . Limitations bibliographic research was carried out by consulting the electronic databases MEDLINE and LILACS until 2005, on the portals of BIREME and the US National Library of Medicine.Free and controlled keywords were used in Portuguese and English, in combination with the Boolean operator AND for specificity.Initially, the controlled keywords were defined in Portuguese by means of the Descritores em Ciências da Saúde -DeCS on the Bireme portal (www.bireme.br),and in English by using the Medical Subject Heading -MeSH on the portal of the US National Library of Medicine -NLM (www.pubmed.com).Next, the bibliographic survey was carried out.
Adverse events: cornea destruction epidemic -1998 In 1998, the Centers for Disease Control and Prevention (CDC) interrupted the use of a new sterilization technology in the United States, which sterilizes through peracetic acid and hydrogen peroxide vapor, due to the occurrence of a cornea destruction epidemic among patients submitted to intraocular ophthalmological surgery.At that time, this technology had not been approved by the Food and DrugAdministration (FDA) to sterilize surgical instruments with lumens or hinges.Nevertheless, it was introduced at the Hospital and the investigation of the epidemic concluded that the sterilization method degrade the metal of cannulated copper and zinc surgical instruments, resulting in the destruction of endothelial cornea cells(6)(7) .Cost analysis of low temperature sterilization -1998In general, the choice of the sterilization technology is based on cost and compared with available technologies.A German study compared the costs of hydrogen peroxide plasma (Sterrad 100®), ETO and formaldehyde sterilizations.The authors included vapor sterilization and all related direct and indirect costs.Plasma sterilization is faster and cheaper than ETO and does not require sparging, thus needing a smaller inventory of instruments;

1998
The reuse of highly complex and high-cost single-use products has been assessed, and the reprocessing of electrophysiology catheters has revealed to be feasible, from the perspective of security as well as efficacy.In this American study, the authors assessed electrophysiology catheter (without lumen), reprocessed five times each, and ablation catheters, reprocessed twenty times each and sterilized in hydrogen peroxide plasma, with satisfactory results.Cost economy is significant when each catheter is used five times.The authors appoint the following study limitations: absence of clinical results in terms of safety, although sterility tests revealed to be satisfactory; and the fact that the tests

Table 1 -
Results of the bibliographic search until 2005, carried out in the BIREME and NLM portals, According to the controlled or free keywords used.São Paulo, *The results of the search with the controlled keyword sterilization were not accessed ** Ethylene oxide = ETO *** Hydrogen peroxide = HP : bone graft sterilization -2001 Bone grafts have been widely used in orthopedic surgeries, despite the risk of transmitting infectious agents from the donor, although bone banks carry out serological tests.Nowadays, there does not exist any sterilization technology without adverse Low-temperature sterilization and new... Goveia VR, Pinheiro SMC, Graziano KU.