(367 days)
The STERRAD® 100S Sterilizer is designed for sterilization of both metal and mommetal medical devices at low temperatures. Because the cycle operates within a dry environment and at low temperatures, it is especially suitable for instruments sensitive to heat and moisture. (See list of recommended Materials in Section 3 of the Operator's Manual.)
The STERRAD® 100S Sterilizer can sterilize instruments which have diffusion-restricted spaces, such as the hinged portion of forceps and scissors.
Metal and nonmetal lumened instruments with inside diameters of 6 mm or larger and lengths of 310 mm or shorter can be processed in the STERRAD® 100S Sterilizer. (See list of recommended Materials in Section 3 of the Operator's Manual)
Medical devices with only a single stainless steel lumen which has an inside diameter equal to or greater than 3 mm and a length less than or equal to 400 mm can be processed in the STERRAD® 100S Sterilizer.
The STERRAD® 100S Sterilizer is a self-contained stand-alone system of hardware and software designed to sterilize medical instruments and devices, using a patented hydrogen peroxide gas plasma process. Hydrogen peroxide vapor is generated by injecting aqueous hydrogen peroxide into the vaporizer bowl where the solution is heated and transformed into a vapor, introducing the vapor into the process chamber under negative pressure and transforming the vapor into a gas plasma with radio frequency (RF) electrical energy.
The equipment (hardware) for the STERRAD® 100S Sterilizer is the same as that of the predicate device, the STERRAD® 100 Sterilizer. (Note that the STERRAD® 100S Sterilizer does contain two additional hardware features, an oil return valve, added for customer convenience; and a door position sensor and control.) The hardware consists of a sterilization chamber onto which is mounted a variety of instruments and components, housed in a covered frame. The system also uses accessories such as disposable sterilant cassettes, reusable instrument trays, printer paper and ink cartridges.
Acceptance Criteria and Device Performance for STERRAD® 100S Sterilizer
The STERRAD® 100S Sterilizer is a hydrogen peroxide gas plasma sterilization system designed to sterilize medical instruments and devices at low temperatures. The validation testing followed an "overkill" approach, demonstrating efficacy under challenging conditions.
1. Acceptance Criteria and Reported Device Performance
The acceptance criterion for sterilization is a Sterility Assurance Level (SAL) of at least 10⁻⁶, meaning there is no more than a one in a million chance of a single viable microorganism remaining after sterilization.
| Acceptance Criteria Category | Specific Acceptance Criterion | Reported Device Performance |
|---|---|---|
| Dose-Response Relationship | Positive "dose response" to increasing hydrogen peroxide injection volume. No spore survivors with 720 µL or greater injection volume under half-cycle conditions. A 10⁻⁶ SAL for a full-cycle. | B. stearothermophilus spore death kinetics data on various materials demonstrated a positive "dose response." No spore survivors on any material with an injection volume of 720 µL or greater under half-cycle conditions (nominal half-cycle volume is 1440 µL). This validates a 10⁻⁶ SAL for a STERRAD® 100S Sterilizer full-cycle. (>6 SLR in a half-cycle exposure). |
| Surface Sterilization | 10⁻⁶ SAL for medical device surface sterilization for all materials listed as recommended for use. | Results demonstrate an SAL of at least 10⁻⁶ for medical device surface sterilization in the complete STERRAD® 100S sterilization process for all recommended materials. |
| Mated Surfaces Sterilization | 10⁻⁶ SAL for mated surface sterilization. | An SAL of 10⁻⁶ was demonstrated for mated surface sterilization in the complete STERRAD® 100S Sterilization process (half-cycle studies with mated biological indicator carriers). |
| Lumen Sterilization (Metal) | 10⁻⁶ SAL for stainless steel lumens (3 x 400 mm). | No spore survivors after multiple half-cycles for stainless steel lumens (3 x 400 mm). These results demonstrate an SAL of 10⁻⁶ for the complete STERRAD® 100S Sterilization process. |
| Lumen Sterilization (Non-metal) | 10⁻⁶ SAL for plastic lumens with inner diameters of 6 mm or larger and lengths of 310 mm or shorter. | All test samples were sterile after processing polyethylene lumens (6 x 310 mm) with B. stearothermophilus spores under half-cycle conditions (3 cycles, 10 test samples each). This demonstrates an SAL of 10⁻⁶. |
| Tyvek-Mylar Pouched Device Sterilization | No spore survivors with half-cycle conditions for 3 x 400 mm stainless steel straight lumens in Tyvek-Mylar pouches. | No spore survivors were observed with the half-cycle conditions for Tyvek pouched stainless steel lumens (with BIs) in a validation tray. |
| Bacteriostasis Testing | No bacteriostatic effect from processed carriers on microorganisms. | All test carriers/materials demonstrated the desired outgrowth within the 14-day incubation period when inoculated with B. stearothermophilus spores. This indicates no bacteriostatic effect, though neoprene required catalase. |
| Sporicidal Microbiological Testing | No growth on carriers (silk suture loops and penicylinders) contaminated with B. subtilis and Cl. sporogenes. | None of the carriers demonstrated growth after AOAC Sporicidal Activity of Disinfectants tests. |
| Simulated Use Testing | Efficacy minimally affected by organic and inorganic soil challenge. A 6.1 log reduction for properly washed devices. | The process is minimally affected by the presence of an organic and inorganic soil challenge. For properly washed devices, a 6.1 log reduction was shown. The process demonstrated effective sterilization of highly resistant spores in diffusion-restricted environments (e.g., scissors hinges). |
| In-Use Sterility Testing | Successful sterilization of actual surgical instruments with open, mated/hinged, and lumened surfaces (3 x 400 mm). | The results demonstrated that the STERRAD® 100S Sterilizer successfully sterilizes actual surgical instruments (stainless steel, open, mated/hinged, and 3x400mm lumened) used in clinical cases. |
| In Use Bacteriostasis/Fungistasis | No bacteriostatic or fungistatic effects seen with processed stainless steel open surfaces, mated/hinged surfaces, and 3 x 400 mm lumened surgical instruments. | The study demonstrated no bacteriostatic or fungistatic effects when processed instruments (stainless steel open, mated/hinged, and 3x400mm lumened) were exposed to Cl. sporogenes, C. albicans, or B. subtilis. |
| Toxicity Testing | No toxic sterilant residuals on processed materials. | Cytotoxicity and in vivo biocompatibility testing of materials processed showed that the sterilization process leaves no toxic sterilant residuals. |
2. Sample Sizes Used for the Test Set and Data Provenance
The document does not explicitly state a singular "test set" sample size in terms of number of devices or total runs, as the testing was multifaceted. However, specific sample sizes are mentioned for certain tests:
- Dose-Response Relationship: "various materials (representative of materials used in medical devices) as spore carriers" were used. The results state "no spore survivors on any material" with sufficient injection volume, but the exact number of material types or replicates is not specified.
- Surface Sterilization: "various substrate materials representative of the material commonly used in re-usable medical devices" were used. "Inoculated spore carriers (with at least 1 x 10⁶ B. stearothermophilus endospores)" were processed, but the precise number of carriers is not given.
- Mated Surfaces Sterilization: "Mated BIs with at least 1 x 10⁶ B. stearothermophilus spores" were used, but the number of mated BIs is not specified.
- Lumen Sterilization (Metal): B. stearothermophilus endospores (>10⁶ spores) were inside stainless steel lumens (3 x 400 mm). There were "no spore survivors after multiple half-cycles," implying multiple lumens and cycles were run, but specific numbers are not provided.
- Lumen Sterilization (Non-metal): "Three cycles were performed with ten test samples in each cycle" for 6 x 310 mm polyethylene lumens. This means a total of 30 test samples.
- Tyvek-Mylar Pouched Device Sterilization: "Ten Tyvek pouched stainless steel lumens, with BIs (>10⁵ B. stearothermophilus spores)," were processed in one half-cycle run.
- Bacteriostasis Testing: "carriers of various materials" were used, but the number is not specified.
- AOAC Sporicidal Activity: "carriers (silk suture loops and penicylinders)" were used, but the number is not specified.
- Simulated Use Testing: "The devices were inoculated with spores...". No specific sample size is given.
- In-Use Sterility Testing: "Devices representative of surface-feature and lumen claims" were "used in routine surgeries at a local hospital." The report states "actual surgical instruments" but does not give a quantity of instruments or tests. Given the context (submission date 1999), this data is retrospective in nature (using previously used instruments).
- In Use Bacteriostasis and Fungistasis Test: "Devices representative of surface features and lumen claims" were selected, but the number is not specified.
Data Provenance: The studies were conducted by Advanced Sterilization Products (ASP), a division of Ethicon, Inc. in Irvine, CA. The "In-Use Sterility Testing" mentions "routine surgeries at a local hospital" and "transported to ASP," suggesting the clinical data originated from a US hospital and was then tested at ASP's facilities. The other studies appear to be laboratory-based validation tests conducted by ASP. All data can be considered retrospective in the context of the device's development and submission.
3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts
The ground truth in this context is microbial inactivation, specifically the absence of viable spores to demonstrate a sterility assurance level (SAL) of 10⁻⁶. This is established through standard microbiological methods involving culture and detection of microbial growth (or lack thereof).
- Number of Experts: The document does not specify the number of individual experts (e.g., microbiologists) who established the ground truth. It refers to the testing being performed by the applicant (ASP). It's reasonable to assume that qualified microbiologists or biotechnicians within ASP's R&D or Quality Assurance departments conducted these studies.
- Qualifications of Experts: The specific qualifications of the individuals performing the microbiological analysis are not explicitly stated (e.g., "radiologist with 10 years of experience"). However, given the nature of the testing (sterilization validation, biological indicator processing, spore counts, SAL determination), it would require individuals with expertise in microbiology, sterilization science, and good laboratory practices. The AOAC and USP methods mentioned imply adherence to recognized standards that require specific technical proficiency.
4. Adjudication Method for the Test Set
Adjudication methods like "2+1" or "3+1" are typically used in clinical studies involving interpretation of medical images or patient outcomes, where there might be inter-reader variability.
For sterilization validation studies, the "ground truth" (i.e., presence or absence of viable microorganisms) is determined by objective microbiological culture methods. The outcome is generally binary (sterile or non-sterile) based on standardized test procedures. Therefore, an "adjudication method" in the sense of expert consensus for subjective interpretation is not applicable to this type of study. The results are based on objective laboratory measurements.
5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done
No, a Multi-Reader Multi-Case (MRMC) comparative effectiveness study was not done.
MRMC studies are typically used to evaluate the diagnostic performance of a new medical imaging device or AI algorithm, often comparing human readers with and without AI assistance across multiple cases. This submission is for a sterilization device, not a diagnostic or imaging device, and its performance is measured by its ability to kill microorganisms, not by human interpretation or diagnosis. Therefore, such a study would not be relevant or appropriate for this device.
6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done
The STERRAD® 100S Sterilizer itself is an automated system. Its performance is evaluated in a standalone manner, meaning the effectiveness of the sterilization cycle is measured directly without human intervention influencing the microbial kill results. The "algorithm" here can be considered the predefined sterilization cycle parameters (temperature, vacuum, H₂O₂ injection, plasma phases).
The performance data presented throughout the summary (Dose-Response, Surface Sterilization, Lumen Sterilization, etc.) represent the standalone performance of the STERRAD® 100S system in achieving sterility. Human operators manage the loading and initiation of the cycle, but the cycle's sporicidal efficacy is intrinsic to the device's design and operating parameters, independent of real-time human interpretation during the sterilization process.
7. The Type of Ground Truth Used
The primary ground truth used for all sterilization efficacy studies is microbiological negativity / absence of viable microorganisms. This is established by:
- Viable Spore Counts: Measuring the initial high load of B. stearothermophilus spores (typically 1 x 10⁶ or higher) on biological indicators (BIs) or inoculated test devices.
- Culture Techniques: After the sterilization cycle, the BIs or test devices are incubated in appropriate growth media (e.g., TSB) to detect any surviving microorganisms. The absence of growth in these cultures confirms sterility for that sample.
- Sterility Assurance Level (SAL): The ground truth is ultimately tied to achieving an SAL of 10⁻⁶, which is a statistical probability derived from these microbial inactivation studies, indicating that the probability of a single viable microorganism occurring on an item after sterilization is less than or equal to one in a million.
Additionally, pathology/histology (implied by "cytotoxicity and in vivo biocompatibility testing") was used to assess the ground truth for biocompatibility and lack of toxic residuals from the sterilization process.
8. The Sample Size for the Training Set
This document describes the validation and performance testing of a physical medical device (sterilizer) and not a software algorithm that requires a "training set" in the machine learning sense. Therefore, the concept of a "training set" as it relates to AI/ML is not applicable here.
The device's operational parameters were likely developed and refined through extensive R&D and engineering studies, which could be seen as an iterative process analogous to training, but not with a distinct "training set" of data in the AI context. The document refers to "Process Variables and Parameters: Rationale and Definition," and "A matrix experiment was performed that tested the process variables of chamber wall temperature and plasma power within specification limits." These experiments helped define the optimal cycle parameters, but are not a "training set" for an algorithm.
9. How the Ground Truth for the Training Set Was Established
Since a "training set" in the AI/ML sense is not applicable to this device, the question of how its ground truth was established is also not applicable.
However, if one were to consider the development of the device's operational parameters as an analog to "training," the "ground truth" during this development phase would have been iteratively established through experimental results showing effective microbial kill under various conditions, leading to the optimized and validated cycle parameters. This would involve repeated microbiological assessments (as described in section 7) to determine which combinations of process variables achieve the desired level of sterility.
§ 880.6860 Ethylene oxide gas sterilizer.
(a)
Identification. An ethylene gas sterilizer is a nonportable device intended for use by a health care provider that uses ethylene oxide (ETO) to sterilize medical products.(b)
Classification. Class II (performance standards).