The goal of this study is to find the best method to use Wellue O2 ring to screen for moderate to severe obstructive sleep apnea. The method that investigators use to screen for moderate to severe obstructive sleep apnea is oxygen desaturation index(ODI). The main questions of this study are

1. What is the best ODI to screen for moderate to severe obstructive sleep apnea?
2. What are the sensitivity, specificity and AUC of the study? In this study, participants are recruited from Sleep center of Thammasat prior to polysomnography. All participants in this study will

1. Undergo polysomnography according to Sleep center of Thammasat protocol 2. Wear Wellue O2 ring when undertaking polysomnography If the polysomnography is switch to PAP titration Wellue O2 ring will be taken out.

Data of Oxygen data from Wellue O2 ring are collected and compared with AHI. Investigators will find the best ODI to screen for obstructive sleep apnea.

Background:

• Obstructive sleep apnea is a highly prevalent sleep-related disease.
• Moderate to severe obstructive sleep apnea is linked with traffic accident and other medical condition such as hypertension, pulmonary hypertension, myocardial infarction, stroke and diabetes mellitus
• Screening for obstructive sleep apnea using questionaires such as STOP-BANG and ESS (Epworth sleepiness scale) provide good sensitivity but low specificity
• Polysomnography used to diagnosed obstructive sleep apnea has limited assessibility and prolonged waiting time.
• Overnight pulse oximetry had been used to screen for obstructive sleep apnea and provided good sensitivity and specificity for screening obstructive sleep apnea using ODI (Oxygen desaturation index)
• Wellue O2 ring, a commercial grade pulse oximeter, with a frequency of measuring oxygen saturation of 0.25 Hz (compare to overnight pulse oximetry of 1 Hz) can measured oxygen saturation overnight with lower cost than overnight pulse oximetry (medical grade device)
• In this study, investigators want to find the best ODI to use to screen for moderate to severe obstructive sleep apnea. Investigators will find the sensitivity specificity and AUC of ROC curver in each ODI.

Outcome

• Sensitivity, Specificiy and area under the curve of ROC curve of each ODI. Sample size calculation
• Referencing previous studies (Kapur VK, Auckley DH, Chowdhuri S, et al. Clinical Practice Guideline for Diagnostic Testing for Adult Obstructive Sleep Apnea: An American Academy of Sleep Medicine Clinical Practice Guideline. J Clin Sleep Med. 2017;13(3):479-504. Published 2017 Mar 15. doi:10.5664/jcsm.6506) The sensitivity of single channel home sleep test is 73% using Z = 1.96 and prevalence of 0.64 and d = 0.1 investigators get a population of 118 people. Investigators collected 42 more people in case of total sleep time < 2 hours.

Recruitment

• Patients are recruited prior to undertaking polysomnography test Eligibility criteria Inclusion criteria
• Patients age ≥ 18 years old Exclusion criteria
• Patients with pacemaker or intra-cardiac defibrillator
• Patients with suspected periodic limb movement disorder, insomnia, parasomnia, nacrolepsy and obesity hypoventilation syndrome
• Patients who canot wear O2 ring
• Patients with congestive heart failure, COPD, Asthma or Neuromuscular disorder
• Patients with desaturation when awake
• Patient with Scleroderma and Raynaud phenomenon

Study procedures

• After inform consent was obtained age, gender, body weight, height, neck circumference,underlying disease, STOP-BANG and ESS score are recorded
• Patients wear Wellue O2 ring when undergoing polysomnography, oxygen data were recorded from wellue O2 ring
• Data of AHI is extracted from the polysomnography report
• Data from wellue O2 ring is exported from wellu2 O2 ring using bluetooth in .csv format.
• Investigators excluded patient with Total sleep time < 2 hrs
• Baseline characteristic, oxygen saturation data and AHI are inputed in STATA version 17
• Investigators find the multiple ODI criteria and find the best ODI with the best sensitivity and specificity and AUC of ROC for screening moderate to severe obstructive sleep apnea.

Inclusion Criteria:

• Age >= 18 years old
• Undertaking polysomnography at Sleep center of Thammasat

Exclusion Criteria:

• Patient with pacemaker or intra-cardiac defibrillator
• Patient suspected to have periodic limb movement disorder, insomnia, parasomnia, narcolepsy, obesity hypoventilation syndrome
• Patient who cannot wear Wellue O2 ring
• Patient suspected to have congestive heart failure, COPD, neuromuscular disorder
• Patient who have baseline O2 saturation below 92%
• Patient who have scleroderma or having Raynaud phenomenon

Patients whom undertaking polysomnography at Sleep center of Thammasat