Abstract
Background: The nocturnal pulse oximetry is used as a validated screening method in the diagnostic approach of Sleep Apnea Syndrome (SAS).
Aim: To assess the role of nocturnal pulse oximetry as a screening method in subjects with morbid obesity (BMI>40 kg/m2), knowing that the basal nocturnal saturation is lower in this patients due to hypoventilation in supine position during sleep.
Method: 87 obese (BMI>40 kg/m2) patients with high pre-test clinical suspicion of SAS (Epworth sleepiness scale >10, snoring, witnessed apneas) were prospectively evaluated by respiratory polygraphy (pulse oximetry, nasal airflow, thoraco-abdominal movements, body position and snoring). We assessed the correlation between the values of Desaturation Index (DI) and Apneea Hypopnea Index (AHI). The cut-off for independent desaturation was 3%.
Results: 82 patients (94.2%) were diagnosed with SAS (AHI>5/hour); mean age: 53.1 ± 11.5 years (range 28-79 years); mean BMI: 45.07±5.1 kg/m2 (range 40-68 kg/m2). The mean DI was 45±26.4 / hour and the mean AHI: 44.2±26.1 / hour. Mean lowest SaO2 was 67.8±13% and mean average SaO2 was 87.9±7.1%. There was a significant correlation between DI and AHI (p<0.001). Also, DI was correlated with lowest SaO2 (p<0.001) and average SaO2 (p=0.02).
Conclusion: Desaturation Index assessed by nocturnal oximetry maintains its utility in the recognition of SAS in morbid obese patients with high clinical pre-test suspicion.
- © 2012 ERS
