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Hemoflow dialyzers are designed for acute and chronic hemodialysis. Hemoflow dialyzers are also appropriate for single or multiple use when reprocessed with 1.5% Citric Acid/95℃.

Device Description

The submission describes a procedure and components used in the reprocessing of Fresenius polysulfone hemodialyzers with 95°C/1.5% citric acid. This involves using radiant heat (moist or dry) at 95°C for 24 hours with the addition of 1.5% citric acid solution.

AI/ML Overview

The provided text is related to a 510(k) submission for a hemodialyzer reprocessing procedure using 95°C/1.5% citric acid. It focuses on demonstrating the substantial equivalence of this new reprocessing method to existing ones. The information required for acceptance criteria and study details is largely based on sterilization and disinfection effectiveness, as well as material compatibility and performance for the reprocessed dialyzers.

Here's an analysis based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

Acceptance Criteria Category	Specific Acceptance Criteria	Reported Device Performance
Microbial Reduction (Disinfection/Sterilization)	Minimum 6 log reduction in bacterial concentration (standard accepted sterilization log reduction).	Achieved at least an 18 log reduction in B. stearothermophilus (indicator organism) with 95°C/1.5% citric acid for 24 hours. A single run at 90°C for 24 hours demonstrated at least a 12 log reduction. No growth observed in SCD media after 95°C for 24 hours and a 96-hour set period.
Bacteriostatic Effect	Solution should not promote microbial proliferation; ideally, a bacteriostatic effect.	1.5% citric acid solution did not meet USP antimicrobial effectiveness test for bactericide, but no organisms proliferated in the solution. Demonstrated to be bacteriostatic.
Material Compatibility (Heat Exposure)	Polysulfone hemodialyzers should not be adversely affected by the disinfection process; heat-labile components require lower temperatures than 121°C.	Plastic components were found heat-labile at 121°C, justifying the need for 95°C. Studies showed "no difference in heat penetration studies of F60 or F80 dialyzers" and "no 'cold' position within the dialyzer" during the 95°C process. Citric acid had "no chemical effect on components."
Toxicity	No evidence of toxicity according to ISO 10993-1 guidelines (with specified exception).	Results indicate no evidence of toxicity based on one of three carcinogenicity tests on dialyzer samples reprocessed ≥15 times.
In Vitro Performance (Membrane Function)	No significant difference in membrane performance (flux rates) compared to non-reprocessed or formaldehyde-reprocessed dialyzers.	No difference in membrane performance due to heat reprocessing with 95°C/1.5% citric acid when compared to non-reprocessed dialyzers or dialyzers reprocessed with 1.5% HCHO and 40°C. Data for low, mid, and high flux polysulfone dialyzers were provided.
In Vivo Product Performance	No significant difference in product performance compared to non-reprocessed or formaldehyde-reprocessed dialyzers.	No difference in product performance due to heat reprocessing with 95°C/1.5% citric acid compared to non-reprocessed hemodialyzers or dialyzers reprocessed with 1.5% HCHO with 40°C incubation.
In Vivo Clinical Data (Patient Outcomes)	No significant differences in patient parameters or intradialytic episodes when using dialyzers reprocessed with the new method compared to the predicate method.	No differences were noted between the two reprocessing procedures (1.5% formaldehyde/40°C vs. 95°C/1.5% citric acid) in patient parameters and intradialytic episodes (hypotension, reactions, etc.).

2. Sample Size Used for the Test Set and Data Provenance

Microbial Reduction (Disinfection/Sterilization):
- Test dialyzers were selected after exposure to blood in "at least 10 reprocessing procedures."
- For kill effectiveness, "10X blood contacted reprocessed F80 dialyzers biologically seeded with approximately 1,000,000 B. stearothermophilus spores" were used.
- "Three test runs were conducted."
- A single run was done at 90°C.
- "24 dialyzers were seeded with the test organism B. stearothermophilus" for a subsequent growth observation test.
- Data Provenance: The studies were conducted by Fresenius Medical Care, suggesting internal, prospective experimental data. The country of origin is not explicitly stated but implies US-based submission context.
Toxicity Testing:
- "Dialyzer samples that were reprocessed a minimum of 15 times" were used. The exact number of samples is not specified beyond "samples."
- Data Provenance: Internal, prospective experimental data.
In Vitro Performance:
- "Each membrane family of Fresenius polysulfone dialyzers; low (F4, F6 and F8), mid (F60M and F80M) and high flux (F60 and F80)" were evaluated. The specific number of dialyzers per family/reprocessing condition is not detailed.
- Data Provenance: Internal, prospective experimental data.
In Vivo Product Performance:
- "All Fresenius polysulfone membrane configurations" were compared. The specific number of devices tested is not detailed.
- Data Provenance: Internal, prospective experimental data (possibly animal or human surrogate studies, but the text doesn't specify which, just "in vivo product performance").
In Vivo Clinical Data:
- "Patients dialyzed with hemodialyzers reprocessed with 1.5% formaldehyde and 40℃ incubation who were then transferred to dialyzers heat reprocessed with 95°C/1.5% citric acid." The number of patients is not specified.
- Data Provenance: Clinical study data, likely prospective given the "transferred" description and follow-up.

3. Number of Experts Used to Establish the Ground Truth for the Test Set and Qualifications of Those Experts

The text does not provide information on the number or qualifications of experts used to establish a "ground truth" in the traditional sense related to a diagnostic or AI device. The ground truth for the device's performance here is based on objective measurements (e.g., microbial counts, temperature, flux rates, toxicity assays, patient monitoring). The regulatory body (FDA) and Fresenius's internal scientists (e.g., Director, Product Development) are involved in reviewing and generating the data, respectively, but not in establishing a subjective "ground truth" through consensus for a test set.

4. Adjudication Method for the Test Set

This concept is not relevant to the type of device and study described. Adjudication methods (like 2+1, 3+1) are typically used for establishing ground truth in diagnostic studies involving human interpretation or subjective assessments. Here, the studies involve objective, measurable outcomes (e.g., sterilization effectiveness, physical performance, toxicity) that don't require such adjudication.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study Was Done, and Effect Size

No, an MRMC comparative effectiveness study was not done. MRMC studies are typically used to assess the performance of diagnostic imaging devices or algorithms where human readers interpret medical images or data, and their performance is compared with and without AI assistance. This submission describes an industrial reprocessing procedure for a medical device (hemodialyzer), not an AI-enabled diagnostic tool.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) Was Done

This question is not applicable as the device is a reprocessing procedure, not an algorithm or AI system. The "standalone performance" of the reprocessing procedure itself (i.e., its ability to disinfect, maintain performance, and be non-toxic) was demonstrated through the various tests described (microbial reduction, in vitro/in vivo performance, toxicity).

7. The Type of Ground Truth Used

The "ground truth" in this context refers to the verifiable outcomes against which the reprocessing procedure's effectiveness is measured. The types of ground truth used include:

Microbial Counts: Direct measurement of viable organisms (e.g., B. stearothermophilus) to establish log reduction, indicating disinfection/sterilization.
Physical/Chemical Measurements: Temperature readings (thermocouples), pH measurements, and quantitative assessment of membrane flux rates.
Laboratory Assays: USP antimicrobial effectiveness test, ISO 10993-1 guidelines for toxicity, indicating specific biological and chemical properties.
Clinical Observations/Outcomes Data: Monitoring patient parameters and intradialytic episodes (hypotension, reactions) in clinical use.

8. The Sample Size for the Training Set

This question is not applicable. The context is the validation of a reprocessing procedure for a medical device, not a machine learning algorithm. Therefore, there is no "training set" in the sense of data used to train an AI model. All described studies are essentially "test sets" or validation experiments for the reprocessing method itself.

9. How the Ground Truth for the Training Set Was Established

This question is not applicable as there is no training set for an AI/algorithm in this submission.

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