Cyclic Alternating Pattern (CAP), Sleep Disordered Breathing, and Automatic Analysis

A translational research using cyclic alternatingpattern (CAP) analysis was performed in premeno-pausal women with complaints of fatigue and a lowbut abnormal apnea–hypopnea index (AHI).Results indicated that apnea and hypopnea do notdescribe well abnormal breathing during sleep inpremenopausal women. Also, nonrapid eye move-ment (NREM) sleep scoring of CAP with automaticanalysiswascloselyrelatedtothoseobtainedbytwoindependent and blind to condition visual scorers.Pearson correlation coefficient showed a significantpositive correlation between a visual analog fatiguescale score and CAP rate (scored either byautomaticanalysis or visual analysis). But no significant corre-lation was noted between visually scored EEGarousalandsamescale.CAPisanimportantadjunc-tion in the investigation of the sleep disturbancepresented by sleep-disordered breathing (SDB) pa-tients. The CAP automatic scoring system tested issufficientlyaccuratetohelpCAPscoring.Currentre-spiratory scoring criteria to evaluate severity of SDBin premenopausal women may be inadequate.IntroductionSleep disruption defined by changes in sleep stagesscored according to the international criteria ofRechtschaffen and Kales [1] has correlated poorlywith common complaints such as fatigue and dec-rements in alertness. The American Sleep DisordersAssociation (ASDA) addition of scoring EEGarousals of 3 seconds or longer [2] has improvedthe detection of sleep disruption but remains insen-sitive to more subtle EEG changes. Correlating sleepdisruptions with subjective complaints is compli-cated by the occurrence of patients with a highAHI in the absence of excessive sleepiness com-plaints. This finding may be related to the factthat breathing events may terminate with a brain-stem activation and not with an EEG arousal. Con-versely, patients mayalso complain of tiredness andfatigue or cognitive impairment during the daytimewhile demonstrating a low number of EEGarousals, that again, fails to correlate with the sever-ity of the daytime symptoms.