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Obstructive Sleep Apnea
Home Sleep Testing
Sleep Disordered Breathing

Watermark Medical (ARES™)

Description and Validation of the Apnea Risk Evaluation System: A Novel Method to Diagnose Sleep Apnea-Hypopnea in the Home.
Westbrook PR, Levendowski DJ, Cvetinovic M, et al. Chest 2005:128;2166-2175.

ARES had a 0.96 correlation with PSG when recorded concurrently and 0.88 for in-home ARES vs. PSG. ARES demonstrated a sensitivity of 97.4 and a specificity of 85.6 in 284 subjects with data acquired concurrently with PSG, and a sensitivity of 91.5 and a specificity of 85.7 in 187 subjects when comparing in-home recordings to PSG. 32 of 35 of the in-home misclassifications were attributed to differences in the percent time supine. Twenty-percent of the subjects included in this study were healthy controls. The failure rate for the in-home comparisons was only 2%.

Validation of a Self-Applied Unattended Monitor for Sleep Disordered Breathing
Ayappa I, Norman R, Seelall V, Rapoport D. J Clin Sleep Med 2008;4(1);26-37.

The correlations between the ARES and PSG for simultaneously acquired recordings was 0.96 using an apnea/hypopnea index with a 4% desaturation (AHI-4%), and 0.93 using a respiratory disturbance index based on Chicago criteria (RDI). The diagnostic sensitivity of in-lab ARES RDI was 0.95 and the specificity was 0.94; comparable measures to PSG for the in-home ARES RDI values were 0.85 and 0.91.

The Impact of Obstructive Sleep Apnea Variability Measured In-Lab versus In-home on Sample Size Calculations.
Levendowski D, Steward D, Woodson BT, et al. Intl Archive Medicine; 2009 2:2

Thirty-six patients were tested by PSG with a 4-month test-retest interval and by ARES with a 6-month interval. The test-retest ARES apnea/hypopnea index (AHI) and apnea index (AI) were more highly correlated (0.65 and 0.68, respectively) as compared to PSG (0.56 and 0.58). The PSG AHI and AI showed a substantial bias toward increased severity at retest (8 and 6 events/hour), while there was no bias for ARES. Test-retest correlations in the percent time supine were 0.72 for ARES and 0.43 for PSG. The sample size required to power a study using PSG would be more than a 2 order of magnitude larger than WM ARES.

Assessment of the test-retest reliability of laboratory polysomnography.
Levendowski DJ, Zack N, Rao S, et al. Sleep Breath. 2008; in-press.

The correlations between PSG results from 20 patients with a 1-month retest interval without a treatment intervention for the AHI was only 0.44, and 0.52 for sleep efficiency, 0.69 for the supine AHI, 0.25 for the non-supine AHI and 0.70 for the percent time supine. There was a bias toward increased AHI severity when comparing the PSG at test vs. retest of 7 event/hour.

Validation of Forehead Venous Pressure as a Measure of Respiratory Effort for the Diagnosis of Sleep Apnea
Popovic D, King C, Guerrero M, et al. J Clin Mon Comp, 2008, in-press.

Fifteen patients were studied during PSG with an esophageal balloon, respiratory effort belts and the FVP (from ARES). Kappa values showed all measures provided good overall agreement comparing obstructive apneas, hypopneas, flow limitation ventilation change and central/mixed events. Comparisons of inter-rater and intra-rater comparisons show that FVP is equivalent to effort belts in detecting events needed to provide the differential diagnoses of sleep disordered breathing.

Assessment of Obstructive Sleep Apnea Risk and Severity in Truck Drivers: Validation of a Screening Questionnaire.
Levendowski D, Olmstead R, Popovic D et al. Sleep Diagnosis and Therapy. 2007: 2(2);20-26.

The sensitivity and specificity of the ARES Screener in predicting who will have an AHI > 5 was 0.94 and 0.79 in 850 subjects. 77% of the transportation workers predicted by ARES Questionnaire to have severe OSA had an AHI > 20.

Prevalence of probable Obstructive Sleep Apnea Risk and Severity in a Population of Dental Patients.
Levendowski DJ, Morgan T, Montague J et al. Sleep Breath. 2008;12(4); 303-309.

Of 331 dental patients studied, 67% of the men and 28% of women were predicted to have an AHI > 5, 96% were confirmed to have sleep disordered breathing > 5 events/hour. 70% of patients predicted to have moderate or severe OSA by WM ARES Screener were found to have an AHI > 20.

Validation study of a portable monitoring device for identifying OSA in a symptomatic patient population.
To Kw, Chan WC, Chan TO et al. Respirology 2009 14(2):270-275.

There were 141 patients who wore the WM ARES while undergoing a PSG study. Results of AHI from the WM ARES study were presented in the order of different scoring criteria--4% oxygen desaturation alone, obstructive events with 1% desaturation plus surrogate arousal criteria. The sensitivity was 0.84 (95% confidence interval (CI): 0.77-0.90) and 0.97 (95% CI: 0.94-0.99), respectively. The specificity was 1, and 0.63 (95% CI: 0.55-0.71), respectively. The receiver operating curve had an area of 0.96 and 0.98, respectively. The WM ARES device has reasonable sensitivity and specificity for diagnosing severe OSAS in symptomatic Chinese patients.

Comparison of Two Limited-Channel Systems for the Diagnosis of Sleep Apnea/Hypopnea in the Home
Westbrook PR, Dickel MJ, Nicholson D, Levendowski D, Zavora T, Simenovic V, Dalati R. Sleep Diagnosis and Therapy. 2007: 2(1);33-37.

A large population of adult surgical patients (n=2877) were screened with the ARES questionnaire. The prevalence of OSA in 207 patients who screened at high risk and completed an ARES in-home sleep study was 82.1%. The estimated prevalence of OSA in the surgical population was 22% with over 70% undiagnosed.

Prevalence of Undiagnosed Obstructive Sleep Apnea Among Adult Surgical Patients in an Academic Medical Center.
Finkel KJ, Searleman AC, Tymkew H, et al. Sleep Medicine, in-press.

The Kappa coefficients between the ARES vs. PSG were 0.88 for the ARES, and 0.69 and 0.66 for the NovaSom 4% and 2% respectively. The ARES provided greater sensitivity than the NovaSom 4% or 2% (100% vs. 78.6% and 85.7%, respectively). The NovaSom 4% provided better specificity thanthe ARES or NovaSom 2% (100% vs. 83.3% and 83.3% respectively). The positive predictive values of the ARES and NovaSome 4% and 2% were essentially equivalent (93.3%, 100% and 93.3%, respectively) while the are ARES provided substantially better negative predictive values (100% vs. 66.7% and 71.4%, respectively).