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The AmeriWater Ozone Disinfection System is an optional accessory for the AmeriWater Bicarb Solution Mix and Distribution System (SDS) cleared for market under K051031 and the AmeriWater Water Purification System (WPS) for Hemodialysis cleared for market under K991519. It is intended for use in hospitals and dialysis clinics for the disinfection of the AmeriWater SDS and WPS system. The disinfection process is completed during off-hours when the SDS or WPS are not being used for patient treatment. The AmeriWater Ozone Disinfection System provides dissolved aqueous ozone concentrations of at least 0.5 ppm with a contact time of at least 30 minutes for disinfection of the WPS and SDS systems (the entire disinfection process takes approximately 2 hours to complete and longer contact times may be necessary based on microbial loads). The Ozone Disinfection System is designed to produce water with a microbial count of 50 CFU/ml or less.

The AmeriWater Ozone Disinfection System is a compact portable device that connects to the AmeriWater Bicarb Solution Mix and Distribution System (SDS) and the AmeriWater Water Purification System (WPS) for Hemodialysis for disinfection of the systems. Microbial reduction is achieved by a combination of disinfection by ozone and by physical removal by draining, flushing, and refilling the system being disinfected with fresh water. The Heatsan system has been designed to be in compliance with the requirements of ANSI/AAMI/ISO 13959:2009 Water for hemodialysis and related therapies and ANSI/AAMI/ISO 26722:2009 Water treatment equipment for hemodialysis applications and related therapies.

The AmeriWater Ozone Disinfection System uses a high technology corona discharge process for producing ozone. Ozone is manufactured by drawing oxygen (O2) into the ozone generator and exposing it to multiple high voltage electrical discharges. This causes a percentage of the oxygen molecules to dissociate and reassemble as ozone (03). The ozone is drawn into the water by a venturi injector / mixer allowing the ozone to be injected into the water under a vacuum condition. The AmeriWater Ozone Disinfection System is a complete unit with ozone generator, venturi injector mixer, gas off chamber with excess ozone gas destruct, feed water flow meter, oxygen flow meter, and vacuum gauge.

The driving force of the AmeriWater Ozone Disinfection System is the distribution pump on the WPS water loop and the mix and distribution pumps on the SDS. A valve arrangement installed on the outlet of the WPS distribution pump and the SDS pumps allow for the diversion of purified water flow into the AmeriWater Ozone Disinfection System and back into the SDS or WPS storage tanks. The pumps force the purified water from the WPS storage tank into the Ozone Disinfection System, which enriches it with ozone and returns it to the WPS storage tank. Likewise, the purified water from the SDS mix and distribution tanks is pumped into the Ozone Disinfection System where it is enriched with ozone and returned to the tanks. When the water flow has been adjusted properly, a vacuum will draw oxygen (from a medical grade oxygen source) into the ozone generator and ozone will be created. The ozone generator has a vacuum switch and will not operate without an adequate vacuum from the venturi injector as indicated on the Ozone Disinfection System vacuum gauge.

The purified water from the WPS or SDS flows into the Ozone system through the feed flow meter and into a venturi injector creating a vacuum that draws the oxygen through the generator creating ozone in concentrations greater than 0.5 ppm. The ozone is then mixed in the ozone rich water enters the gas off tank to remove any excess, un-dissolved ozone gas. The water-ozone mixture enters and exits at the bottom of the gas off tank. The excess (un-dissolved) ozone will slowly displace the water in the tank and is vented at the top of the tank. The excess ozone gas then enters the ozone destruct chamber where it is destroyed while the ozone-rich water is directed back to the system being disinfected. Ozone concentrations are monitored using RPC Ozone Test strips, cleared for market under K132344.

The intended disinfection endpoint for the AmeriWater Ozone Disinfection System with the AmeriWater Water Disinfection System (WPS) and the AmeriWater Solution System (SDS) following disinfection and rinse is a total bacterial count less than or equal to 50 CFU/mL; when the system being disinfected is properly maintained (with bacterial counts < 100 CFU/mL; and endotoxin < 0.25 EU/mL). In the event that the system being disinfected has not been properly maintained, additional contact time or additional disinfection cycles may be required to achieve the desired end point. ANSI/AAMI/ISO 13959:2009 requires that monitoring of the water storage tanks for bacteria and endotoxin levels is accomplished indirectly by monitoring the water at the distribution loop. Water distribution systems are monitored by taking samples of the water at the first and last outlets of the water distribution loop. ANSI/AAMI/ISO 26722:2009 specifies that an ozone level of 0.5 ppm, sustained for at least 10 minutes, is considered necessary to kill bacterial organisms. AmeriWater recommends an ozone level of 0.5 ppm or greater for disinfection with a contact time of at least 30 minutes. The AmeriWater disinfection process takes approximately 2 hours to complete using the Ozone Disinfection System. This includes the time to build the ozone concentration in the storage tank and loop, as well as contact times.

The AmeriWater Ozone Disinfection System is designed to disinfect the AmeriWater Bicarb Solution Mix and Distribution System (SDS) and the AmeriWater Water Purification System (WPS) for Hemodialysis. The overall goal is to produce water with a microbial count of 50 CFU/ml or less.

Here's an analysis of the acceptance criteria and the study that proves the device meets them, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

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

• Sample Size for Test Set:

  • Microbial Challenge (Bacteria, Yeast, Mold, Mycobacteria): Not explicitly stated as a number of distinct samples, but tests were conducted with a "range of test organisms" in a "microbial challenge solution" under "worst-case conditions."
    • WPS Testing: Included test runs with 48-hour incubation, 30-day incubation (representing recommended disinfection frequency), and simulated use testing.
    • SDS Testing: Included test runs with 48-hour incubation, 6-day incubation (representing recommended disinfection frequency), and simulated use testing.
  • Virucidal Efficacy: Not explicitly stated as a number of distinct samples, but tested using "Herpes simplex virus type 1" and "Poliovirus type 1" under "worst-case conditions."
  • Biocompatibility/Leaching: Not explicitly stated as a number of samples, but involved "extended exposure" over the "expected operating life of the device."
  • Electrical Safety: Not explicitly stated as a number of units, but device was "third-party tested and listed to UL 979."

• Data Provenance: The document does not specify the country of origin for the data. The studies described are non-clinical testing and appear to be conducted as part of the device's validation. They are likely prospective studies specifically designed to test the device's performance against the established criteria.

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

The document does not provide information on the number of experts or their qualifications for establishing the ground truth for the test set in the context of typical diagnostic device studies (e.g., radiologist consensus).

In this case, the "ground truth" for the microbial efficacy testing would be the actual microbial count reductions and inactivation, determined through laboratory methods (e.g., plating, enumeration), rather than expert interpretation of images or clinical outcomes. For biocompatibility, the ground truth would be chemical analysis of leachates and material integrity. These are objective measures determined by validated laboratory assays.

4. Adjudication Method for the Test Set

The concept of an "adjudication method" (like 2+1 or 3+1) is typically relevant for studies where human interpretation or subjective assessment is involved, especially in clinical diagnostic accuracy studies where disagreements among readers need resolution.

For the non-clinical performance and safety tests described here (microbial efficacy, virucidal efficacy, biocompatibility, electrical safety), the results are typically quantitative and objectively measured by laboratory instruments and protocols. Therefore, a human "adjudication method" as described is not applicable. The results would be confirmed through repeat testing, calibration of equipment, and adherence to standard laboratory practices.

5. If a Multi Reader Multi Case (MRMC) Comparative Effectiveness Study was done

No, an MRMC comparative effectiveness study was not done. This type of study is used to assess the effectiveness of a diagnostic device when used by human readers, often comparing performance with and without AI assistance. The AmeriWater Ozone Disinfection System is a disinfection system, not a diagnostic device that involves human interpretation of results.

6. If a Standalone (i.e. algorithm only without human-in-the-loop performance) was done

Yes, the studies described are essentially standalone performance studies for the device. The device (AmeriWater Ozone Disinfection System) is functioning as an automated system to achieve disinfection, and its performance is evaluated directly on its ability to meet the microbial reduction, virus inactivation, and safety criteria. There is no "human-in-the-loop" interaction in the core function of the disinfection process itself that would be evaluated in these non-clinical tests.

7. The Type of Ground Truth Used

• Microbial Efficacy (Bacteria, Yeast, Mold, Mycobacteria): Laboratory-determined microbial counts (CFU/mL) and log reduction, based on standard microbiological assay methods.
• Virucidal Efficacy: Laboratory-determined viral inactivation, based on standard virological assay methods.
• Biocompatibility/Leaching: Chemical analysis of leachates (e.g., for specific toxins, TOC levels) and visual inspection for material degradation.
• Safety (Ozone levels, Electrical): Instrumental measurements of ozone concentration (water and ambient air) and electrical parameters against established regulatory/safety standards (OSHA, FDA, UL 979).

8. The Sample Size for the Training Set

The document describes non-clinical performance and safety testing for a medical device (an ozone disinfection system). This is not an AI/machine learning device, so the concept of a "training set" in the context of algorithm development is not applicable. The device operates based on physical and chemical principles of ozone generation and disinfection, not on a machine learning model trained on a dataset.

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

As stated above, a "training set" is not relevant for this type of device.

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