K. Rees et al., AROUSAL RESPONSES FROM APNEIC EVENTS DURING NON-RAPID-EYE-MOVEMENT SLEEP, American journal of respiratory and critical care medicine, 152(3), 1995, pp. 1016-1021
Citations number
27
Categorie Soggetti
Emergency Medicine & Critical Care","Respiratory System
Patients with obstructive sleep apnea (OSA) experience severe sleep di
sruption and consequent daytime sleepiness. Current arousal scoring cr
iteria show that some obstructive apneic events do not end in a recogn
izable cortical electroencephalographic (EEC) arousal. It is not known
whether events that end in an obvious EEC arousal differ from those t
hat do not, in terms of EEG frequency changes during the apneic event,
the respiratory effort developed prior to apnea termination, the degr
ee of the postapneic increase in blood pressure, or changes in CO2 ten
sions. We studied 15 patients with OSA in early Stage 2 sleep and anal
yzed obstructive apneic events with and without typical EEG arousals,
defining an arousal as a frequency shift to waking alpha rhythm of 1 s
or longer. EEC signals were digitized and analyzed by fast Fourier tr
ansform during and immediately after each apnea, The median EEG freque
ncy and mean pleural pressure of the first and second halves of the ap
neic episode were compared with that of the first breath. Peak pleural
pressure was measured just before the end of the apneic episode. Syst
olic and diastolic blood pressures and CO2 tensions were measured at t
he onset and termination of apnea. For each patient, 10 events that en
ded in EEC arousal were compared with 10 events that did not. Mean apn
ea duration did not differ for the two groups of events. Median EEG fr
equency and pleural pressure increased significantly from 8.14 to 9.25
Hz and 15.4 to 22,1 cm H2O, respectively, as the apnea progressed, bu
t there was no difference between the groups nor any difference in the
peak pleural pressure. The increase in blood pressure and CO2 tension
at apnea termination was similar for events with and without cortical
EEG arousal. These data show that the arousal response is continuous
and not discrete, and is variable, and that conventional arousal crite
ria may underestimate the severity of sleep disruption. The postapneic
increase in blood pressure, unlike the shift in EEC frequency, was co
nsistently related to apnea termination, and accordingly represents a
useful marker of autonomic and brain-stem arousal.