The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts

SENSITIVITY AND SPECIFICITY OF OVERNIGHT PULSE OXIMETRY AS COMPARED TO LIMITED SLEEP STUDY IN THE DIAGNOSIS OF SLEEP APNOEA SYNDROME (SAS)(AN IRISH PERSPECTIVE)

Asaad A. Khan1



Background: A. Khan, A. Fitzpatrick, M McNeill, O. Martin, A. O'Brien.
Respiratory Dept. Midland Regional Hospital, Mullingar. Overnight pulse oximetry is a simple, cheap, user-friendly, widely available test. Its' role in the diagnosis of sleep apnoea syndrome (SAS) is controversial. There is no published data on this test in an Irish population. We aimed to determine the sensitivity and specificity of this test in the diagnosis of SAS.
We performed a retrospective analysis of the charts of 128 patients suspected of SAS; all patients underwent a limited sleep study and nocturnal oximetry on the same night. An oxygen desaturation index (ODI) (number events per hour of sleep, where the oxygen saturation decreased by >4% for at least 10 seconds) was calculated with the oximeter; an ODI of > 5 was defined as a positive test.

SAS was diagnosed in 88 patients (AHI >5). The sensitivity, specificity, positive and negative predictive values for overnight oximetry were: for an ODI ?5 (94.3%, 62.5%, 84.6%, 83.3%), ODI?10 (83.0%, 87.5%, 93.6%, 70.0%) and ODI ?15 (67.0%, 95.0%, 96.7%, 58.4%) respectively. The accuracy for an ODI ?5 was 0.76, ODI ?10 was 0.60 and ODI ?15 was 0.47.

Our results showed that overnight pulse oximetry (ODI >5) is a highly sensitive screening device for SAS in an Irish population, though limited by low specificity. In an environment of limited resources, with prolonged waiting lists, consideration of this method to screen all referrals, with resultant appropriate prioritisation, should be considered.