RESUMO
UNLABELLED: Nap polysomnography (NPSG) is a technique for rapid diagnosis of sleep apnea-hypopnea syndrome (SAHS). Although an apnea-hypopnea index (AHI) over 10 indicates a diagnosis of SAHS, treatment with nasal continuous positive airway pressure (CPAP) starts when the AHI exceeds 30. OBJECTIVE: To determine the diagnostic yield of NPSG for initiating CPAP and to evaluate the different types of polysomnographic findings. METHODS: Two hundred ninety-six patients suspected of having SAHS underwent NPSG lasting three hours. NPSG findings were considered positive at AHI > 30; normal at AHI < 10 with non-REM and REM sleep (more than 10%); invalid if the patient slept less than 60 minutes; and inconclusive if AHI was between 10 and 30 with REM, if AHI was < 30 without REM, or if upper airway resistance syndrome (UAS) was suspected. Positive and normal polysomnographic findings were considered diagnostic and the invalid and inconclusive findings were considered non-diagnostic. We also observed whether SAHS was predominantly obstructive, predominantly hypopneic, central-mixed, central-obstructive or miscellaneous, based on the type of event detected mot often during NPSG. RESULTS: Seventy percent of the NPSG were diagnostic (55% positive and 15% normal) and 30% were not (12% invalid and 18% inconclusive). Fifty-five percent of the positive NPSGs were predominantly obstructive, 29% were predominantly hypopneic, 8% were central-mixed, 4% were central-obstructive and 4% were miscellaneous. CONCLUSIONS: The diagnostic value of NPSG for initiating CPAP treatment is high. Predominantly hypopneic forms are particularly common.