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The AVL 9181 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 9181 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. The AVL 9181 is an improved design of our existing 9180 Electrolyte Analyzer [K961458] with the addition of an Autosampler to allow automatic sampling of up to 18 sample cups. The 9181 is exactly equivalent to the AVL 9180 with the exception of this single, additional feature. The manual needle mechanism of the 9180 was replaced with the automated needle mechanism from the AVL 988-4. The electronic circuitry to control the needle mechanism are incorporated into the 9180 display board. The sampler is taken from the 988-4 without modification except that the connector is changed to a smaller type. The 9180 main board already incorporated the controller for the sampler. The 9180 software was modified to add the automatic sampling feature. Calibration and measurement sequences are taken without alteration from the 9180 (sample volume, timing and algorithms). Once the sample probe is positioned in the sample cup, aspiration, measurement, wash and recalibration sequences are identical to the 9180.

Here's a breakdown of the acceptance criteria and study information for the AVL 9181 Electrolyte Analyzer, based on the provided text:

AVL 9181 Electrolyte Analyzer: Acceptance Criteria and Study Details

The provided document describes the AVL 9181 Electrolyte Analyzer as an improved design of the existing AVL 9180 Electrolyte Analyzer [K961458], with the primary addition of an Autosampler. The studies presented focus on demonstrating that this new feature, and the overall device, performs equivalently to the predicate devices and existing manual methods.

1. Table of Acceptance Criteria and Reported Device Performance

The document does not explicitly present a table of predetermined "acceptance criteria" in the format of specific thresholds for accuracy, precision, etc. Instead, it describes performance characteristics that were evaluated and concluded to be comparable to predicate devices and manual methods. The general acceptance criterion appears to be "no significant difference" (p < 0.05) in measurement values compared to predicate devices and between manual and automated modes.

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

• Precision Test: "2 runs per day with 2 replicates per run for 20 days on two model AVL 9181 analyzers" for each configuration and specimen type. This implies 80 individual measurements per configuration/specimen type (2 runs * 2 replicates * 20 days).
• Linearity in N.I.S.T. Standard Reference Material: The specific number of measurements or distinct samples is not given, but it utilized N.I.S.T. SRM 956a Electrolyte in Human Serum.
• Linearity in Serum: "All samples were analyzed in pairs on each of two of AVL 9181 instruments in each configuration: Na/K/Cl, Na/K/iCa and Na/K/Li." Also "in pairs on each of several instrument types" for comparison. The exact number of samples is not stated.
• Linearity in Urine: "analysis of random patient urine specimens" on the specified instruments. The exact number of samples is not stated.
• Clinical Tests: "Specimens analyzed in these tests were remnant from patient specimens of both whole blood and serum collected for routing analysis on existing instrumentation." The exact number of patient specimens is not stated.

Data Provenance:

• The N.I.S.T. SRM 956a is a certified reference material, likely of US origin.
• "Random patient urine specimens" and "remnant from patient specimens of both whole blood and serum" indicate retrospective clinical data.
• The locations of the "four field tests" are not specified, so the country of origin for the clinical data is not explicitly stated, but the submission is to the FDA, suggesting US-based or internationally recognized standards.

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

The ground truth was established by measurements from predicate devices (e.g., AVL 9180, IL Model 943 Flame Emission Photometer, Labconco Digital Chloridometer) and standard reference materials (N.I.S.T. SRM 956a). These are considered the 'gold standard' for the respective analytes. There were no human experts used to establish a "ground truth" in the interpretive sense (like reading an image). The accuracy of these measurements is inherent to the certified materials and established predicate devices.

The personnel operating the device for the clinical trials were "minimally trained personnel qualified to perform and to report these values in a clinical laboratory setting," but they were performing analyses, not establishing a new ground truth.

4. Adjudication Method for the Test Set

No explicit adjudication method is described, as the ground truth was established by instrumental measurements and certified reference materials, not human interpretation requiring adjudication. Statistical analysis (e.g., p < 0.05) was used for comparison.

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 electrolyte analyzer, not an interpretive medical imaging or diagnostic device that would typically involve multiple human readers. The comparison was between automated device measurements and predicate device measurements.

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

Yes, a standalone performance evaluation was done. The studies assessed the AVL 9181's performance (linearity, precision, and correlation) when operating on its own, both in manual and automated modes, against established methods and predicate devices. The "algorithm" here refers to the internal analytical processes and measurement taking place within the instrument.

7. The Type of Ground Truth Used

The ground truth used was a combination of:

• Certified Reference Materials: Specifically N.I.S.T. SRM 956a Electrolyte in Human Serum for linearity studies.
• Measurements from Legally Marketed Predicate Devices: These instruments serve as the established "truth" against which the new device's measurements are compared. Examples include the AVL 9180, IL Model 943 Flame Emission Photometer, Labconco Digital Chloridometer, and AVL 983 Electrolyte Analyzers.
• Established Analytical Methods: The principles of measurement and calibration sequences are identical to predicate devices, implying that these established methods constitute the "truth" for how these analytes are measured.

8. The Sample Size for the Training Set

The document does not specify a separate training set or its sample size. This type of medical device (an in-vitro diagnostic analyzer) typically relies on engineering design and validation against known standards and predicate devices rather than "training" in the machine learning sense. The device's "training" for its algorithms would be the manufacturing calibration and software development process, which isn't described in terms of a "training set."

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

As there is no explicit "training set" described in the context of machine learning, the question of how its ground truth was established is not applicable. The device's operational parameters are based on established chemical and electrical principles for ion-selective electrodes, calibrated against standards and proven in predicate devices.

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