SESSION TITLE: Sleep Posters I
SESSION TYPE: Original Investigation Poster
PRESENTED ON: Wednesday, October 29, 2014 at 01:30 PM - 02:30 PM
PURPOSE: Risk factors for obesity hypoventilation syndrome (OHS) have recently been identified. However, the prevalence of these risk factors in a population of obese patients presenting for polysomnography has yet to be established. We conducted a retrospective chart review to evaluate this question.
METHODS: We reviewed the polysomngrams of all obese (BMI ≥ 30) adults with newly diagnosed obstructive sleep apnea (OSA) (defined as an apnea-hypopnea index (AHI) ≥ 5) at our institution over a one year period. Those with a prior history of lung disease (e.g. COPD) were excluded. We collected data on age, sex, BMI, AHI, mean overnight SpO2, percentage of total sleep time (% TST) with SpO2 < 90%, and serum bicarbonate (HCO3) level. We then analyzed the prevalence of previously identified risk factors for OHS including BMI ≥ 40, AHI ≥ 55, mean overnight SpO2 ≤ 90%, SpO2 < 90% for ≥ 25% TST, and serum HCO3 ≥ 27. We also analyzed the prevalence of AHI ≥ 65, mean overnight SpO2 ≤ 85%, and SpO2 < 90% for ≥ 50% TST.
RESULTS: A total of 1168 patients were screened, of which 281 met the inclusion criteria. Twenty-seven (9.6%) were excluded due to a history of lung disease generating a cohort of 254 patients. Seventy-one patients (27.9%) had a BMI ≥ 40. Sixty-four patients (25.2%) had a serum HCO3 level ≥ 27. Twenty-one (8.3%), 32 (12.6%), and 43 (16.9%) patients had an AHI ≥ 55, a mean overnight SpO2 ≤ 90%, and spent ≥ 25% TST with SpO2 < 90%, respectively. Thirteen patients (5.1%) had all three of these risk factors and their presence was correlated by cumulative logistic regression with the requirement for conversion from CPAP to BIPAP during the titration phase of split night testing (p= 0.013). In addition, 14 (5.5%), 4 (1.6%), and 22 (8.7%) patients had an AHI ≥ 65, a mean overnight SpO2 ≤ 85%, and spent ≥ 50% TST with SpO2 < 90%, respectively.
CONCLUSIONS: Factors that place patients at increased risk for OHS are highly prevalent in a cohort of adult patients with newly diagnosed OSA.
CLINICAL IMPLICATIONS: The sensitivity and specificity of these risk factor and the actual prevalence of OHS in this population remains unknown. Further evaluation of these risk factors as well as measurement of arterial or end tidal CO2 in this population is warranted.
DISCLOSURE: The following authors have nothing to disclose: Thomas Keller, Jessica Schmidt, Ling Cai, Richard Waldhorn
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