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The CipherOx CRI Tablet is indicated for continuous noninvasive monitoring of functional oxygen saturation of arterial hemoglobin (SpO2), pulse rate (measured by an SpO2 sensor), and the Compensatory Reserve Index (CRI), which trends changes in intravascular volume relative to the individual patient's response to hypovolemia.

For patients with a finger thickness of 0.3" to 1" in hospital and pre-hospital settings.

CRI trends with changes in intravascular volume relative to the individual patient's response to hypovolemia, and should only be used by qualified medical providers as an adjunct to rather than as a replacement for traditional hemodynamic measures. CRI is indicated for adults (19-36 years old) in the supine position under non-motion conditions and without cardiovascular disease. CRI has not been studied in trauma patients.

The CipherOx CRI Tablet consists of a Nonin Onyx II Model 9560 finger pulse oximeter (previously cleared under K081285) that communicates by Bluetooth with a Cybernet CyberMed T10 tablet PC. The CipherOx CRI Tablet is a continuous, multi-parameter monitor that displays SpO2, Heart Rate (HR), photoplethysmograph (PPG) waveform images, and the Compensatory Reserve Index (CRI) value and historical trend-line.

CRI is an index related to the physiologic changes induced by intravascular fluid loss and ranges from 0 to 1, where 1 indicates a normal subject and 0 indicates a subject who has undergone significant physiological effects from loss of fluid volume.

Here's a breakdown of the acceptance criteria and study information for the CipherOx CRI Tablet, based on the provided text:

Acceptance Criteria and Device Performance

The core acceptance criterion for the CipherOx CRI Tablet appears to be the accurate estimation of CRI values, specifically the root-mean-squared error (RMSE) between estimated and reference CRI.

Study Information

2. Sample size used for the test set and the data provenance:

• LBNP Verification Study: 20 healthy participants.
  • Data Provenance: The text does not explicitly state the country of origin, but the development and studies seem to be conducted by Flashback Technologies in Boulder, Colorado. The data is prospective, gathered specifically for the study.
• Blood Draw Validation Study: 42 healthy participants (ages 19 to 36).
  • Data Provenance: Similar to the LBNP study, the country of origin is not explicitly stated but implied to be the US. The data is prospective, gathered specifically for the study.

3. Number of experts used to establish the ground truth for the test set and the qualifications of those experts:

The text does not mention the use of experts to establish a "ground truth" in the traditional sense (e.g., diagnosis by radiologists). Instead, the ground truth for CRI was established physiologically:

• LBNP Study: Reference CRI values were defined as CRI = 1 - LBNPcurrent / LBNPcollapse, where LBNPcollapse refers to the LBNP pressure level at the point a subject either had a precipitous fall in systolic blood pressure below 80 mmHg and/or voluntary subject termination due to discomfort or expression of presyncopal symptoms (or until completion of -100 mmHg). This relies on objective physiological measurements (blood pressure) and subjective patient reporting (presyncopal symptoms).
• Blood Draw Study: The "ground truth" for the blood draw study was the actual volume of blood removed and the observation of symptoms (e.g., systolic blood pressure <80 mmHg or a 30% drop in mean arterial pressure) during blood loss, indicating hemodynamic decompensation.

There is no mention of experts adjudicating these physiological ground truths.

4. Adjudication method (e.g., 2+1, 3+1, none) for the test set:

Not applicable. As described in point 3, the ground truth was established by physiological measurements and direct observation of patient responses to induced hypovolemia, not by expert consensus or adjudication.

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:

No, an MRMC comparative effectiveness study was not conducted for the CipherOx CRI Tablet. The studies focused on the performance of the device itself against physiological reference points.

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

Yes, the core performance testing (LBNP verification and blood draw validation) appears to be standalone algorithm performance. The device calculates CRI based on PPG data. While usability assessment involved users interpreting CRI values, the primary validation of the algorithm's accuracy in calculating CRI was performed independently.

7. The type of ground truth used (expert consensus, pathology, outcomes data, etc.):

The ground truth used was physiologically derived and based on direct physiological measurements and observed patient responses to induced hypovolemia.

• LBNP Study: Direct measurement of LBNP levels and observation of a precipitous fall in systolic blood pressure or patient-reported presyncopal symptoms.
• Blood Draw Study: Direct measurement of blood volume removed and observation of physiological symptoms (systolic blood pressure, mean arterial pressure drop) leading to early termination.

8. The sample size for the training set:

• LBNP Training Dataset: 230 healthy human volunteers.

9. How the ground truth for the training set was established:

The ground truth for the training set was established through the same LBNP methodology as described for the LBNP verification study:

• LBNP Training: Reference PPG signals were collected on 230 healthy human volunteers undergoing lower body negative pressure (LBNP) to the point of presyncope. Reference CRI values were then defined as CRI = 1 - LBNPcurrent / LBNPcollapse, where LBNPcollapse refers to the LBNP pressure level at which the subject reached objective (BP drop) or subjective (presyncopal symptoms) stopping criteria. This allowed the algorithm to learn the relationship between PPG changes and known levels of induced intravascular volume changes.

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