Extraction and stability of ethylene oxide residue in medical devices

The impact of increasing saline flush volume to reduce the amount of residual air in the delivery system of aortic prostheses-a randomized controlled trial

Background

Air embolism is a known risk during thoracic endovascular aortic repair (TEVAR) and is associated with an incomplete deairing of the delivery system despite the saline lavage recommended by the instructions for use (IFU). As the delivery systems are identical and residual air remains frequently in the abdominal aortic aneurysm sac, endovascular aortic repair (EVAR) can be used to examine the effectiveness of deairing maneuvers. We aimed to evaluate whether increasing the flush volume can result in a more complete deairing.

Methods

Patients undergoing EVAR were randomly assigned according to flushing volume (Group A, 1× IFU; Group B, 4× IFU). The Terumo Aortic Anaconda and Treo and Cook Zenith Alpha Abdominal stent grafts were randomly implanted in equal distribution (10-10-10). The quantity of air trapped in the aneurysm sac was measured using a pre-discharge computed tomography angiography (CTA). Thirty patients were enrolled and equally distributed between the two groups, with no differences observed in any demographic or anatomical factors.

Results

The presence of air was less frequent in Group A compared to that in Group B [7 (47%) vs. 13 (87%), p = .02], and the air volume was less in Group A compared to that in Group B (103.5 ± 210.4 vs. 175.5 ± 175.0 mm3, p = .04). Additionally, the volume of trapped air was higher with the Anaconda graft type (p = .025).

Discussion

These findings suggest that increased flushing volume is associated with a higher amount of trapped air; thus, following the IFU might be associated with a reduced risk of air embolization. Furthermore, significant differences were identified between devices in terms of the amount of trapped air.

Clinical trial registration

[NCT04909190], [ClinicalTrials.gov].

Identification and quantification of ethylene oxide in sterilized medical devices using multiple headspace GC/MS measurement

This manuscript, based on the ISO 10993-7 approach, describes a multiple HS-GC measurement of residual EO present in sterilized plastic samples. The quantification of EO is done, according to the ISO standard, by addition of EO amounts extracted for each repeated extraction. During the method development, the specificity of the detection of EO regarding acetaldehyde (structural isomer of EO) which may be formed from EO has been ensured and different tests were performed to check a possible influence of the sample preparation. Assays to maximize EO extraction were performed for different materials (Cyclo-olefine Copolymer (COC), Cyclo-olefine Polymer (COP), Silicon, Polyurethane (PUR)) changing extraction temperatures and times for the headspace and the pre-thermal treatment. Results highlight that depending on the material, EO can be more or less retained and thus thermal extraction conditions to maximize the amount of extractible EO from plastics may change accordingly. For COC syringes a validation according to ICH guidelines and an inter-laboratories study were performed. The method has been used for a market survey of EO sterilized medical devices, results obtained are reported in this manuscript.

Solvent or thermal extraction of ethylene oxide from polymeric materials: Medical device considerations

Ethylene oxide (EO) gas is commonly used to sterilize medical devices. Bioavailable residual EO, however, presents a significant toxicity risk to patients. Residual EO is assessed using international standards describing extraction conditions for different medical device applications. We examine a series of polymers and explore different extraction conditions to determine residual EO. Materials were sterilized with EO and exhaustively extracted in water, in one of three organic solvents, or in air using thermal desorption. The EO exhaustively extracted varies significantly and is dictated by two factors: the EO that permeates the material during sterilization; and the effectiveness of the extraction protocol in flushing residual EO from the material. Extracted EO is maximized by a close matches between Hildebrand solubility parameters δ_polymer , δ_EO , and δ_solvent . There remain complexities to resolve, however, because maximized EO uptake and detection are accompanied by great variability. These observations may inform protocols for material selection, sterilization, and EO extraction. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2455-2463, 2018.

Emission characteristics of plastic syringes sterilized with ethylene oxide--a controlled study

OBJECTIVES

This study examined the emission characteristics of ethylene oxide (EO)-sterilized syringes under various environmental conditions, aiming to develop control strategies to minimize worker exposure.

METHODS

Experiments were performed in a facility in which temperature, relative humidity (RH), and air change rate (ACR) were controlled.

RESULTS

Analytical results indicate that the main effects of the four test variables on kinetic parameters were statistically significant (p < 0.05), except for the effect of the product on the decay rate constant, the effect of ACR on maximum EO concentration, and effect of RH on the area under the curve-days 1 and 2. The interactive effects among test variables were also evident, indicating complex emission behaviors. The mean EO emission factors during the days 1 and 2 and at the 48th hour for the 1- and 30-ml products were 2302, 1301, and 1031 mg/m(3)/h, and 871, 490, and 381 mg/m(3)/h, respectively. The times required for air EO concentrations from tested products to return to approximately 0 and 1 ppm (permissible limit) were 417 and 218 h, respectively.

CONCLUSIONS

Plastic content, temperature, RH, and ACR affected EO emissions. ACR is an achievable means of control; however, the aeration area/system should be isolated to ensure adequate ventilation is achieved.