RT Journal Article
SR Electronic
T1 Nocturnal oximetry for the diagnosis of the sleep apnoea hypopnoea syndrome: a method to reduce the number of polysomnographies?
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 968
OP 971
DO 10.1136/thx.54.11.968
VO 54
IS 11
A1 Eusebi Chiner
A1 Jaime Signes-Costa
A1 Juan Manuel Arriero
A1 Juan Marco
A1 Isabel Fuentes
A1 Antonia Sergado
YR 1999
UL http://thorax.bmj.com/content/54/11/968.abstract
AB BACKGROUND Polysomnography (PSG) is currently the “gold standard” for the diagnosis of the sleep apnoea hypopnoea syndrome (SAHS). Nocturnal oximetry (NO) has been used with contradictory results. A prospective study was performed to determine the accuracy of NO as a diagnostic tool and to evaluate the reduction in the number of PSGs if the diagnosis of SAHS had been established by this method.METHODS Two hundred and seventy five patients with a clinical suspicion of SAHS were admitted to undergo, in the same night, full PSG and NO. Desaturation was defined as a fall in the haemoglobin saturation level (Sao 2) to lower than 4% from the baseline level and an oxygen desaturation index per hour (ODI) was obtained in each patient with three cut off points: ⩾5 (ODI-5), ⩾10 (ODI-10), and ⩾15 (ODI-15).RESULTS SAHS was diagnosed in 216 patients (194 men). After withdrawing patients with abnormal lung function (forced expiratory volume in one second (FEV1) lower than 80% predicted), sensitivity (SE), specificity (SP), positive and negative predictive values (PPV and NPV) of NO were: ODI-5 (80%, 89%, 97%, 48%); ODI-10 (71%, 93%, 97%, 42%); ODI-15 (63%, 96%, 99%, 38%). The accuracy for each ODI was 0.81, 0.75, and 0.70, respectively. If NO had been considered as a diagnostic tool and PSG had been performed only in patients with a negative NO (false negative and true negative) and those with a positive NO and abnormal pulmonary function tests, 135/275 (ODI-5), 156/275 (ODI-10), and 170/275 (ODI-15) PSGs would have been performed, a reduction of 140, 119, and 105, respectively.CONCLUSION Nocturnal oximetry in patients with suspected SAHS and normal spirometric values permits the institution of therapeutic measures in most patients.