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The ISE Electrodes on the RX Imola can be used for measurement of the electrolytes sodium, potassium and chloride in serum and urine and for use in diagnosis and treatment of electrolyte imbalance. For in vitro diagnostic use only.

RX imola is an automated clinical chemistry analyzer complete with dedicated analyzer software. Software functions of the analyzer include the facility to interact with a host computer for direct download of test method selection details for individual samples. A barcode system is used for the rapid identification of patient samples, reagents and QC samples, In addition, the RX imola is fitted with an Ion Selective Electrode (ISE) module that operates in conjunction with specific electrodes for the quantitative in vitro diagnostic determination of Sodium, Potassium and Chloride in serum and urine.

The provided document is a 510(k) summary for a medical device (ISE Electrodes) and outlines the performance characteristics to demonstrate substantial equivalence to a predicate device. It focuses on the analytical performance of the device rather than a clinical study involving human patients or complex AI algorithms. Therefore, many of the requested points related to multi-reader multi-case studies, expert ground truth establishment for AI, and training/test set sample sizes for AI are not applicable to this type of submission.

The document details the acceptance criteria and the study that proves the device meets those criteria for analytical performance.

1. Table of Acceptance Criteria and Reported Device Performance

For this type of device (Ion Selective Electrodes for measuring common electrolytes), the "acceptance criteria" are typically defined by demonstrating that the new modified device performs equivalently to the existing cleared predicate device and meets established analytical performance guidelines (e.g., CLSI standards for precision, linearity, and interference). The document implicitly defines acceptance by stating "The acceptance criteria ... was met" or "The results... support the claimed measuring ranges."

Here's a summary of the performance demonstrated based on the provided text:

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

The "test set" in this context refers to the samples used for analytical validation studies.

• Precision Studies:
  • Serum: Two levels of control material and at least five human serum samples for each analyte (Sodium, Potassium, Chloride). Tested twice per day for 20 non-consecutive days, two replicates per run. This totals 80 data points per measured sample/control (20 days * 2 runs/day * 2 replicates/run).
  • Urine: Two levels of urine controls and at least five urine patient pools for each analyte. Tested twice per day for 20 non-consecutive days, two replicates per run. This totals 80 data points per measured sample/control.
• Linearity Studies: 9 levels of samples used for each analyte and specimen type.
• Method Comparison (Correlation):
  • Serum: 105 patient serum samples for Sodium, 109 for Potassium, 104 for Chloride.
  • Urine: 72 patient urine samples for Sodium, 84 for Potassium, 90 for Chloride.
• Data Provenance: The document does not explicitly state the country of origin for the patient samples. The studies were conducted in-house by Randox Laboratories Limited, which is based in the United Kingdom. The studies were retrospective in the sense that they used collected samples to validate the device's performance, not in the sense of analyzing pre-existing patient data outside a controlled study.

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

• N/A. This is an in vitro diagnostic (IVD) device for measuring electrolyte concentrations using Ion Selective Electrodes. The "ground truth" for analytical performance studies is established by quantitative measurements using reference methods or by the known concentrations of controls/calibrators, not by human expert interpretation like radiologists.

4. Adjudication Method for the Test Set

• N/A. As this is an analytical performance study for an IVD device, there is no human adjudication method required. Performance is based on quantitative measurements.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done, If so, what was the effect size of how much human readers improve with AI vs without AI assistance

• N/A. This is not an AI-based device, nor is it a device that involves human "readers" interpreting images or clinical data. Therefore, an MRMC study is not relevant.

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

• Partially Applicable / Context Dependent. The device (ISE Electrodes on the RX Imola) performs measurements automatically. The performance data presented (precision, linearity, interference, method comparison) is the "standalone" performance of the device as it directly measures the analytes, without requiring human "interpretation" of the analytical result itself beyond standard lab procedures. There is no separate algorithm being tested in the AI sense.

7. The Type of Ground Truth Used

• Reference Method / Known Concentration:
  • For precision and linearity studies, ground truth is established by using control materials and prepared linearity samples with known, validated concentrations or statistically derived consensus values from repeated measurements.
  • For method comparison, the "ground truth" is effectively the measurements obtained from the predicate device (the RX imola with the previous ISE unit, K052914), against which the new device (RX imola with new ISE electrodes, K230890) is correlated to demonstrate equivalence.
  • For interference studies, known interfering substances are added at specific concentrations to samples to evaluate their effect on the measurement.

8. The Sample Size for the Training Set

• N/A (in the AI/machine learning sense). This device does not involve a "training set" in the context of machine learning. It's a chemical measurement system with established electrochemical principles. Standard calibration and quality control procedures are part of its normal operation, but these are not "training sets" in the AI development sense.

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

• N/A (in the AI/machine learning sense). As there is no AI training set, this question is not applicable. The device's operational "knowledge" comes from its manufacturing specifications, calibration protocols using reference materials, and the underlying physical and chemical principles of ion-selective electrodes.

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