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The Somfit D is a single-use, non-invasive prescription device for home use with patients suspected to have sleep-related breathing disorders. The Somfit D is a diagnostic aid for the detection of sleep-related breathing disorders, sleep staging (REM, N1, N2, N3, Wake), and snoring level. The Somfit D system acquires electrical data from three frontal electrodes, tri-axial accelerometer data, acoustical and plethysmographic data. The Somfit D calculates and reports to clinicians EEG/EOG channels, Sleep Stages, SpO2, Peripheral Arterial Tonometry signal, pulse rate, and snoring level. The Somfit D calculates and reports to clinicians derived parameters such as Peripheral Arterial Tonometry-derived Apnea Hypopnea Index, Obstructive Desaturation Index; and hypnogram-derived indices such as time in each sleep stage. Somfit D data is not intended to be used as the sole or primary basis for diagnosing any sleep-related breathing disorder, prescribing treatment, or determining whether additional diagnostic assessment is warranted. The Somfit D is not intended for use as life support equipment, for example vital signs monitoring in intensive care unit. The Somfit D is a prescription device indicated for adult patients aged 21 years and over.

The Somfit D is a home-based sleep monitoring device which records signals from the patient's forehead. Somfit D is a wearable, low voltage, battery operated device which is attached to subject forehead via a self-adhesive and disposable skin electrode patch. The electrodes are placed on the anterior Prefrontal cortex (PFC) at the Fp1 and Fp2 positions according to the 10/20 EEG system. The device allows for recording of two frontal EEG signals, pulse rate, SPO2, PAT, PPG, motion, and snore. Somfit D uses a mobile phone application to acquire data wirelessly via Bluetooth BLE technology, then transfer into a secure cloud, for management, storage and post-processing. The software reports measured parameters in a format compatible with the American Academy of Sleep Medicine guidelines, including sleep time, ODI, pAHI and conventional graphical displays such as a hypnogram.

The provided FDA 510(k) clearance letter and Somfit D 510(k) Summary describe the acceptance criteria and the study that proves the device meets those criteria. However, it explicitly states that the Somfit D is substantially equivalent to the predicate device, Somfit (K231546), and therefore, the performance data for the Somfit D is derived from the studies conducted on the Somfit. The summary then refers to already submitted and approved studies for the Somfit device.

Here's a breakdown of the requested information based on the provided document:

Acceptance Criteria and Device Performance (Derived from Predicate Device, Somfit)

Table 1: Acceptance Criteria and Reported Device Performance

Study Details (Pertaining to the Predicate Device, Somfit, as explicitly stated for Somfit D equivalence)

1. Sample sizes used for the test set and the data provenance:

   • Oximeter Validation: Controlled desaturation study in accordance with ISO 80601-2-61. Specific sample size not specified in this document, but implied to be sufficient for standard compliance. Data provenance is implied to be from a "Hypoxia Lab." The document doesn't specify if it was retrospective or prospective, or country of origin, but clinical studies for FDA clearance are typically prospective to ensure controlled conditions.
   • Home Sleep Apnea Test Validation (pAHI, ODI, Sleep Staging): A "Multi-Site Clinical Study" was conducted. Specific sample sizes for each of these validations are not provided in this summary. The document states "clinical data for the purpose of the predicate device Somfit (K231546), already submitted and approved," indicating these details would be found in the original Somfit 510(k) submission. The provenance is from "Multi-Site Clinical Study," implying multiple locations, likely within the regulatory jurisdiction where the clearance was sought (e.g., US, Australia). It's implied to be prospective for validation purposes.

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

   • This information is not explicitly stated in the provided 510(k) summary for any of the clinical validations (Oximeter, pAHI, ODI, Sleep Staging). It only mentions that the studies were "meaningful validations" and "concordance," implying comparison to a gold standard. For sleep staging, ground truth is typically established by certified polysomnography technologists and/or sleep physicians.

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

   • This information is not explicitly stated in the provided 510(k) summary for any of the clinical validations.

4. 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 MRMC study is mentioned. The Somfit D (and its predicate Somfit) is described as a diagnostic aid that calculates and reports parameters to clinicians. It's not presented as an AI-assissted reading tool for human interpretation, but rather a device that quantifies specific physiological signals and derives standard indices. The human role is in interpretation of the reported data, not in an AI-assisted reading workflow.

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

   • Yes, the device (Somfit D, through its predicate Somfit) performs standalone algorithmic analysis to calculate:
     • Sleep Stages (REM, N1, N2, N3, Wake)
     • SpO2
     • Peripheral Arterial Tonometry (PAT) signal
     • Pulse rate
     • Snoring level
     • PAT-derived Apnea Hypopnea Index (pAHI)
     • Obstructive Desaturation Index (ODI)
     • Hypnogram-derived indices (e.g., time in each sleep stage)
   • The "meaningful validation" studies for these parameters (pAHI, ODI, Sleep Staging) suggest a comparison of the device's algorithmic outputs against established ground truth.

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

   • Oximeter Validation: Performed in a "Hypoxia Lab," implying comparison to a highly accurate laboratory reference oximeter or blood gas analysis (gold standard for SpO2 measurements).
   • Home Sleep Apnea Test Validation (pAHI, ODI, Sleep Staging): While not explicitly stated, for HSAT devices, "ground truth" for pAHI and ODI is typically derived from comparison to full in-lab Polysomnography (PSG) data scored by a certified sleep technologist and/or interpreted by a board-certified sleep physician, which is considered the clinical gold standard. For sleep staging, the ground truth would be expert-scored PSG recordings.

7. The sample size for the training set:

   • This information is not provided in the summary. The summary focuses on the validation studies, which imply the device's algorithms were already developed and trained.

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

   • This information is not provided in the summary, as it pertains to the development phase rather than the validation phase described.

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