Validity of overnight pulse oximetry as a screening tool of obstructive sleep apnea

Abstract

Background: Polysomnography (PSG) is the gold standard for diagnosing obstructive sleep apnea (OSA). However, it is time-consuming, expensive and expertise is required. So, number of alternatives to PSG has been proposed. Study was performed to analyse the sensitivity, specificity and accuracy of NO as a diagnostic tool in patients suspected to have SAHS and to reduce the number of saved PSGs Methods: 40 middle aged patients clinically suspected to have OSAHS. They were calssified into 2 groups: Group I SAHS comprised 33 patients with AHI > 5. Group II Non SAHS comprised 7 patients with AHI All patients where subjeted to the following: 1- OSA screening questionnaire. 2 (BMI) Kg/m 2 , (NC) cm, cardiac, chest, ENT examination. 3- Investigation in the form of (ABG), chest x-ray, (ECG) and spirometry. 4- full PSG and overnight oximetry which were performed simultaneously. Results: The baseline O2 saturation derived from PSG and oximetry were (93.33±2.32, 91.50±2.79) respectively. The BMI and NC were significantly increseased in SAHS group than Non-SAHS group.. The overnight oxygen desaturation index of oximetry was significantly lower in SAHS group. Minimal spo2 of PSG was significantly lower in SAHS group. The best predicted cutoff values of overnight pulse oximetry using ODI for mild to moderate OSA patient diagnosis was (14.7800) with 87.88% sensitivity, 88.71% specificity and. However, the optimal cutoff values for sever OSA diagnosis was (52.5500) with 86.67%sensitivity, 96%specificity. Conclusion: Overnight pulse oximetry may considerd diagnostic tool in patients suspected to have SAHS with excellent diagnostic sensitivity, specificity and accuracy increased with severity.