4.3.4 Limited Exposure Devices

4.3.4 Limited exposure devices:
The average daily dose of EO to patient should not exceed 4mg.
The average daily dose of ECH to patient should not exceed 9mg.
4.3.5 Tolerable contact limits for surface contacting devices and implants:
4.3.5.1 Overview: TCL is expressed in units of micrograms per square centimetre for EO and milligrams per square centimeters for ECH. The unit of square centimeters represents the surface area of the patient-device interface.
4.3.5.2 Tolerable contact limit for EO: Either the EO TCL for surface contacting devices and implants should not exceed 10 µg/cm2 or it should exhibit negligible irritation as specified in ISO 10993-10.
4.3.5.3 Tolerable contact limit for ECH for surface contacting devices: Either the ECH
Solvent extraction procedures that are combined with headspace gas analysis are described in K.4.4 and such procedures are able to separate EO from co-extracted interfering chemicals from the sample matrix. 4.4.6.3.3 Residual ethylene chlorohydrin: Water is typically used to extract residual ECH from medical devices using methods similar to those described for determining residual EO.
4.4.7 Data analysis and interpretation:
4.4.7.1 Calculation of amount of residue extracted:
The concentration of residue observed in the extracts, Ce, is converted to the amount delivered to a patient, in milligrams, Md, as follows.
Residue extracted by simulated use may be calculated as follows:
Md = ∑n1 (Cen× Ven) (1)
Residue extracted by exhaustive extraction may be calculated as follows: Md = ∑n1 (Cen× Ven)× md/ms (2) where Md is the extract residue, in milligrams n is the number of extractions
Ce is the amount of EO in milligrams per millilitre of
For limited exposure devices: Madd = Md (5)
5. Product release
5.1 General:
A product is in compliance with this part of ISO 10993 when it meets the requirements for EO and ECH. If sufficient experimental data on residue diffusion kinetics are available, it may be possible to group devices for quality assurance testing based on similarity of materials, manufacturing processes and use (Annex D).
For release of batches of EO-sterilized product one of the two methods in 5.2 and 5.3 should be used.
5.2 Release of data without dissipation curve data:
When dissipation curve data is not available on a product the product may be released if it is in compliance with this part of ISO 10993
5.3 Procedure for product release using residue dissipation curves:
Dissipation curves are used to estimate the post-sterilization time required for products mainly for EO in compliance with 4.3. Products should be released to the market place according to predetermined post-sterilization times and conditions. Re-sterilization of product and the presence of other EO-sterilized medical devices in adjacent areas should also be considered when obtaining experimental data to generate such dissipation