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The AVL 9180 Electrolyte Analyzer is intended to be used for the measurement of sodium, potassium, chloride, ionized calcium and lithium in whole blood, serum or plasma, urine, dialysate solutions, or QC materials as appropriate by minimally trained personnel qualified to perform and to report these values in a clinical laboratory setting. These analytes are commonly used in the diagnosis and management of patients with a broad range of renal, metabolic and cardiovascular disorders and, as such, have come to be among those which are considered by the American Association of Clinical Chemistry to have the potential of being life threatening if left uncontrolled.

The AVL 9180 Electrolyte Analyzer is a microprocessor-based instrument using ionselective electrodes for the measurement of sodium, chloride, ionized calcium and lithium. The user is able to select any one of the measurement modes: whole blood, serum, urine, standard, OC material, acetate or bicarbonate dialysate, depending on the sample type to be analyzed. The analyzer automatically processes the sample through the necessary steps, then prints and displays the results.

In the blood, serum and QC measuring modes, the results for sodium and potassium are reported by default as flame photometry equivalent; chloride, ionized calcium and lithium are reported as ISE direct potentiometric values. The urine mode allows for the measurement of prediluted urine samples for sodium, potassium and chloride. The acetate, bicarbonate and standard modes allow for the measurement of aqueous standards and dialysate solutions and reports as ISE direct potentiometric values.

The provided text describes the AVL 9180 Electrolyte Analyzer, an ion-specific electrolyte analyzer for measuring sodium, potassium, chloride, ionized calcium, and lithium. The submission focuses on demonstrating the substantial equivalence and performance of the new device compared to existing predicate devices.

Here's an analysis of the acceptance criteria and study information:

1. Table of Acceptance Criteria and Reported Device Performance

The acceptance criteria are not explicitly stated as numerical targets in the provided text (e.g., "correlation coefficient > 0.95"). Instead, the document implies that the device meets acceptance criteria if its performance is comparable to predicate devices and falls within "manufacturers claims and expectations." The core of the performance evaluation relies on correlation coefficients, slopes, and intercepts from comparative studies, demonstrating the agreement between the AVL 9180 and established methods.

The tables presented in the document are the reported device performance. I will present a summary table outlining the key performance metrics from the various comparative studies, grouped by parameter and comparator.

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

• Aqueous Linearity Standards: 300 samples for Sodium, Potassium; 100 samples for Chloride, ionized Calcium, Lithium. Data provenance: Gravimetrically prepared from N.I.S.T. traceable salts (non-clinical, laboratory setting).
• Serum Linearity (vs. Flame Absorbance): 50 samples for Sodium, Potassium; 15 samples for Lithium. Data provenance: Commercially prepared serum linearity standards and random patient serum samples (non-clinical, likely laboratory setting).
• Serum Linearity (vs. ISE Direct Potentiometry - AVL 983, 984, 985): 50 samples for Sodium, Potassium, Chloride, ionized Calcium; 15 samples for Lithium. Data provenance: Commercially prepared serum linearity standards and random patient serum samples (non-clinical, likely laboratory setting).
• Serum Linearity (vs. ISE Direct Potentiometry with flame correlation - AVL 9130, 9140): 50 samples for Sodium, Potassium, Chloride, ionized Calcium. Data provenance: Commercially prepared serum linearity standards and random patient serum samples (non-clinical, likely laboratory setting).
• Urine Linearity (vs. direct ISE - AVL 983): 56 samples for Sodium, Potassium, Chloride. Data provenance: Random patient urine specimens (non-clinical, likely laboratory setting).
• Urine Linearity (vs. Flame Absorbance - IL 943): 56 samples for Sodium, Potassium. Data provenance: Random patient urine specimens (non-clinical, likely laboratory setting).
• Urine Linearity (vs. Chloridometry - Labconco Digital): 56 samples for Chloride. Data provenance: Random patient urine specimens (non-clinical, likely laboratory setting).
• Clinical Field Tests:
  • Vs. KODAK Ektachem XR700: 103 samples for Sodium, Potassium, Chloride.
  • Vs. other unspecified predicate devices: 102 samples for Sodium, Potassium, Chloride, ionized Calcium in one comparison; 102 samples for Sodium, Potassium, ionized Calcium in another; 104 samples for Lithium in another; 15 samples for Lithium in another comparison.
  • Data provenance: "remnant from patient specimens collected for routine analysis on existing instrumentation" in a clinical setting. This indicates prospective or retrospective use of patient data from a clinical environment. The country of origin is not specified but presumably the USA, given the 510(k) submission to the FDA.

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

The document does not mention the use of experts to establish ground truth for the test sets. The ground truth is established by the measurements from:

• N.I.S.T. traceable salts (for aqueous linearity).
• Predicate devices which are recognized and established methods (Flame Absorbance Emission Spectroscopy, existing AVL ISE analyzers, Labconco Digital Chloridometer, KODAK Ektachem XR700).

4. Adjudication Method for the Test Set

No adjudication method is mentioned. The ground truth is established by the specified reference methods/predicate devices.

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

No, an MRMC comparative effectiveness study was not done. The device is an automated electrolyte analyzer, not an imaging device requiring human interpretation, so this type of study is not applicable.

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

Yes, the studies presented are standalone performance evaluations of the AVL 9180 Electrolyte Analyzer. The device is a self-contained unit that performs measurements automatically ("The analyzer automatically processes the sample through the necessary steps"). The clinical field tests also state "operated by personnel trained to perform and report these analyses," indicating the device is used in a standalone manner with trained operators.

7. The Type of Ground Truth Used

The ground truth used for the studies is:

• Gravimetrically prepared N.I.S.T. traceable standards (for aqueous linearity).
• Measurements from legally marketed predicate devices (Flame Absorbance Emission Spectroscopy, existing AVL 983, AVL 984, AVL 985, AVL 9130, AVL 9140 Electrolyte Analyzers, IL 943 Flame Photometer, Labconco Digital Chloridometer, KODAK Ektachem XR700). These predicate devices represent established and accepted methods for electrolyte measurement, serving as the de facto "ground truth" for demonstrating equivalence.

8. The Sample Size for the Training Set

The document does not specify a separate "training set" in the context of machine learning. The AVL 9180 is a microprocessor-based instrument using ion-selective electrodes, which relies on electrochemical principles rather than machine learning models that require distinct training and test sets. The "calibration" mentioned is an internal process for the instrument's electrodes and sensors, not a machine learning training phase.

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

Since there is no explicit mention of a "training set" in the machine learning sense, this question is not applicable. However, for the instrument's calibration (which can be considered analogous to "training" in a broad sense for analytical instruments), the document mentions:

• "A 2-point calibration is performed automatically every 4 hours in READY mode, and a 1-point calibration is performed automatically with each measurement."
• "Aqueous linearity standards were gravimetrically prepared from N.I.S.T. traceable salts and measured on each of six AVL 9180 instruments..."

This implies that N.I.S.T. traceable salts and potentially internal calibration solutions are used to establish the "ground truth" for the device's internal calibration processes.

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