[Validation of half-night polysomnography for sleep apnea/hypoapnea syndrome].
A diagnosis of sleep apnea/hypopnea syndrome (SAHS) is based on clinical signs and nighttime polysomnograms. Brief polysomnography has been proposed as an alternative to all-night recording.


OBJECTIVE
The aim of this study was to determine whether a polysomnograms obtained during the first half of the night is sufficient for establishing a diagnosis of SAHS and to determine the correlation between polysomnographic variables recorded during the first four hours (half the study time) with those recorded over the full eight hours (full study time), as well as to determine diagnostic agreement.


METHODS
Thirty-five patients suspected of having SAHS were studied prospectively. Baseline polysomnograms were scored blindly by two independent observers following standard methods. A diagnosis of SAHS was made according to guidelines of the Spanish Society of Pneumology and Chest Surgery. During the first half of the night and up to the end of each recording period we gathered neurophysiological and respiratory variables and diagnostic impressions.


RESULTS
The correlation between variables (sleep stage, overall AHI, REM-AHI, non-REM-AHI and sleep efficiency) recorded in the first half of the night and throughout the night was significant (p < 0.05) by both Pearson's correlation coefficient (r) and by the intraclass correlation coefficient (ICC). In 33 of 35 patients (94.3%) diagnostic agreement was achieved (95% CI 80.84-99.30); when SAHS was severe, agreement was 100%.


CONCLUSIONS
Based on these results, we conclude that for patients with a diagnosis of severe SAHS during the first half of the night, data recorded during the second half can be considered supplementary.
Alonso Alvarez
M L
ML
Unidad de Trastornos Respiratorios del Sueño, Hospital General Yagiie, Burgos.
Fernández Martínez de Septiem
C
C
Alonso Mediavilla
C
C
Martínez González
M
M
Teran Santos
J
J
Rodríguez Pascual
L
L
Cordero Guevara
J
J
D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D011446:Prospective Studies; D012891:Sleep Apnea Syndromes / Q000175:diagnosis*; D013997:Time Factors