A
recent study demonstrated the utility of peripheral arterial tonometry
(PAT)-based devices in diagnosing obstructive sleep apnea (OSA), particularly during
the COVID-19 pandemic. The study highlighted the correlation between OSA
severity and various physiological parameters. The authors suggest that these
devices offer a viable alternative for OSA diagnosis, especially in
resource-constrained settings or when polysomnography (PSG) is not feasible.
These
findings are published in Indian Journal of Sleep Medicine in June 2025.
Obstructive Sleep
Apnea (OSA) affects nearly 1 billion people globally and an estimated 104
million in India. Although polysomnography (PSG) remains the gold standard for
diagnosis, limited access has led to endorsement of Home Sleep Apnea Testing
(HSAT). Peripheral arterial tonometry (PAT)-based devices, which measure blood
flow and oxygenation, are increasingly used to assess OSA severity and
cardiovascular risk. This retrospective study evaluated a PAT-based device at
an Indian tertiary care center, highlighting its relevance during the COVID-19
pandemic when remote diagnostics were essential.
Researchers
retrospectively analyzed 55 patients with symptoms suggestive of OSA and high
STOP-BANG or Epworth Sleepiness scores using an FDA-approved PAT-based device (NightOwl™).
Patients with prior OSA or conditions mimicking OSA were excluded, and PSG was
not feasible due to the pandemic. Data from March 2022 to February 2023 were
evaluated based on device-recorded physiological parameters.
Most participants were male
(74.5%) and overweight or obese (81.1%). Of the 55 patients, 50 were diagnosed
with OSA, including 27 classified as severe. The device showed satisfactory
performance, with only one test failure reported.
Key Findings from the Study are:
The
study established significant correlations between OSA severity and various
physiological parameters:
•
Nocturnal Hypoxia: Minimum
oxygen saturation (SpO2) showed a strong negative correlation with the
Apnea-Hypopnea Index (AHI) (R = –0.764). Severe OSA cases exhibited the lowest
minimum SpO2 levels, with 26 out of 27 severe patients displaying levels below
80%.
•
T90 Values: Nocturnal hypoxia,
measured by T90 (percentage of cumulative time spent below 90% oxygen
saturation), correlated noticeably with OSA severity. Severe OSA categories had
significantly higher average T90 values compared to mild or moderate cases.
•
Cardiac Manifestations: Ectopic
beats were prevalent in the OSA-positive cohort, occurring in 62% of diagnosed
cases, supporting findings that cardiac arrhythmias are common in OSA patients.
•
Other Correlations: A strong
correlation was identified between the Oxygen Desaturation Index (ODI > 3%)
and AHI values (R = 0.97). However, no significant correlation was found
between AHI values and Body Mass Index (BMI).Commenting on the findings, Col (Dr) Manu Chopra, Professor & Head, Dept of Respiratory Medicine, Army institute of Cardiothoracic Sciences, AFMC, Pune, noted, “Using a simple finger-based home sleep test, we were able to reliably
diagnose obstructive sleep apnea and assess its severity in patients with high
clinical suspicion. This shows that validated PAT-based devices can serve as a
practical alternative to laboratory sleep studies, particularly in settings
where access to polysomnography is limited.”
He further
emphasized the real-world challenges associated with wider implementation,
stating, “Wider adoption of home sleep testing will require adequate
patient education, physician familiarity with interpreting device-generated
data, and clear pathways for referral to polysomnography when results are
inconclusive.”
The study highlights
PAT-based devices as practical diagnostic tools where PSG access is limited. It
emphasizes the importance of multi-night testing due to AHI variability and
suggests that OSA severity assessment should extend beyond AHI, incorporating
parameters such as nocturnal hypoxia (T90) and ODI to better guide
cardiovascular risk management.
Reference: Chopra M, Tripathi S, Upadhyay M, Tyagi R, Kishore K. Analyzing Obstructive Sleep Apnea Patients Diagnosed with Peripheral Arterial Tonometry-based Diagnostic Device: Retrospective Study from Indian Tertiary Care Center. Indian Sleep Med 2025; 20 (2):35-40.