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The Nonin® Model 3231 Finger Pulse Oximeter is a small, lightweight, portable device indicated for use in measuring and displaying functional oxygen saturation of arterial hemoglobin (%SpO2) and pulse rate of patients who are well or poorly perfused. It is intended for spot-checking of adult and pediatric patients with digits between 0.8 - 2.5 cm (0.3 - 1.0 inch) thick.

Model 3231 Pulse oximeter is a small, lightweight, portable, digit pulse oximeter that displays numerical values for functional oxygen saturation of arterial hemoglobin (SpO2) and pulse rate by measuring the absorption of red and infrared (IR) light passing through perfused tissue. Changes in the absorption caused by the pulsation of blood in the vascular bed are used to determine oxygen saturation and pulse rate. Light emitting diodes (LEDs) are contained within the device along with the photo detector, which is on the opposite side of the probe from the LEDs. The SpO2 and pulse rate are displayed on the LCD display contained within the device. A color LCD provides a visual indication of the pulse signal, while blinking at the corresponding pulse rate. The display will indicate if there is poor pulse quality that may affect the readings. All associated electronics and the microcontroller are within the sensor, which is activated by placing on a patient's digit. This simple operation activates the internal circuitry automatically upon application. The device is intended for spot-checking adult and pediatric patients who are well or poorly perfused.

The modification of the Model 3230 to the Model 3231, include the removal of Bluetooth LE 4.0 and the addition USB 2.0 for serial communication. This modification includes moving from batteries to the USB 2.0 to power the Model 3231. The oximeter circuitry, software and electro optical elements of the Model 3231 are identical to the Model 3230. There are no technological characteristic changes to the device that affect the measurement or display of SpO2 or pulse rate to the user.

Here's an analysis of the acceptance criteria and study information for the Nonin Model 3231 Finger Pulse Oximeter, based on the provided text:

1. Table of Acceptance Criteria and Reported Device Performance

Note: For accuracy specifications, the document states "Identical" to the predicate model (Model 3230), which was cleared by FDA. This implies that the acceptance criteria for these accuracy metrics were met by the Model 3231, as it is stated to have the same performance characteristics.

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

The document mentions "predicate laboratory and clinical hypoxia accuracy testing," but does not specify the sample size for these tests for the Model 3231 or its predicate.

The data provenance is not explicitly stated as retrospective or prospective, nor are specific countries of origin mentioned for the data. However, the testing is done to ensure compliance with international standards (e.g., IEC, ISO), suggesting a general clinical testing environment rather than a specific geographic location.

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

The document does not provide information on the number of experts used or their qualifications for establishing ground truth, particularly for the clinical hypoxia accuracy testing.

4. Adjudication Method for the Test Set

The document does not specify an adjudication method (e.g., 2+1, 3+1, none) for the test set.

5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study

A multi-reader multi-case (MRMC) comparative effectiveness study was not conducted or reported in this document. The device is a standalone pulse oximeter, not an AI-assisted diagnostic tool for human readers.

6. Standalone (Algorithm Only Without Human-in-the-Loop Performance) Study

Yes, a standalone performance assessment was done. The performance testing for SpO2 and pulse rate accuracy (including under low perfusion) is a standalone evaluation of the device's measurement capabilities. The "Performance" test also indicates compliance with ISO 80601-2-61, which relates to basic safety and essential performance of pulse oximeter equipment.

7. Type of Ground Truth Used

The ground truth for pulse oximeters is typically established through:

• Clinical hypoxia studies: Involving human subjects who are induced into various levels of hypoxia, with arterial blood gas analysis (co-oximetry) serving as the reference standard for actual arterial oxygen saturation (SaO2). The oximeter's SpO2 readings are then compared against the SaO2.
• Controlled laboratory conditions: For assessing performance characteristics like signal processing, optical accuracy, and resistance to interference.

While the document generally refers to "clinical hypoxia accuracy testing," it doesn't detail the precise method of ground truth establishment beyond this. Given the device's nature, the ground truth would be from direct measurements of arterial oxygen saturation using a gold standard method.

8. Sample Size for the Training Set

The document describes the Model 3231 as having identical "oximeter circuitry, software and electro optical elements" as the predicate Model 3230. Since this is a hardware device with embedded software, rather than a machine learning algorithm that is "trained," the concept of a "training set" in the context of AI/ML is not directly applicable. The device's underlying algorithms for SpO2 calculation would have been developed and validated through extensive data, but this wouldn't be referred to as a "training set" in the typical ML sense. The provided text does not specify a training set size.

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

As explained above, the concept of a "training set" for a traditional medical device like a pulse oximeter (which predates widespread AI/ML application) isn't directly applicable. The embedded algorithms would have been developed based on scientific principles of spectrophotometry and validated against gold standard measurements (e.g., co-oximetry in clinical hypoxia studies), but this process isn't typically described as establishing "ground truth for a training set." The document does not provide this information directly.

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