Chest

Chest

Volume 95, Issue 2, February 1989, Pages 279-283
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Intracranial Pressure and Obstructive Sleep Apnea

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In order to describe variation in AP and ICP during OSA, six patients with severe OSA were examined, with determination of ICP, AP, CVP, respiration, tcPO2, tcPCO2, and nocturnal sleep polygraphy. During apnea, elevations of AP and ICP were observed, related to the apneic episodes. The elevations in pressure were only observed in relation to apneic episodes. While awake, none of the patients showed pressure elevations. There were highly significant correlations between duration of apnea and variation in AP and ICP and between variations in AP and ICP. Values for ICP while awake were above normal (>15 mm Hg; intracranial hypertension) in four of six patients. Morning ICP was higher than evening ICP. Systolic, mean, and diastolic ICP and AP increased during sleep above awake values. The ICP increased during NREM stages 1 to 4, and the highest values were observed during REM sleep. Vascular response was not changed during REM sleep, and the higher ICP during REM could solely be explained by the longer apneas during REM sleep. The CPP decreased during apnea.

(Chest 1989; 95:279-83)

ICP=intracranial pressure; OSA = obstructive sleep apnea; AP = intra-arterial pressure; EOG = electro-oculogram; CPP=cerebral perfusion pressure

Section snippets

MATERIALS AND METHODS

Six patients were selected by the following criteria: (1) mean number of apneas (apnea index) more than 40 apneas per hour; (2) mean duration of apnea longer than 20 seconds; (3) only OSA; (4) no medication taken; (5) normal findings on neurologic examination; and (6) a normal CT of the brain. Sleep was analyzed by use of central and occipital electrodes (C3, C4, O1, and 02), EOG, and chin EMG. Sleep scoring was performed according to standard methods.5

Respiration was measured by inductive

RESULTS

The patients' clinical data are given in Table 1. The body mass index and blood pressure were slightly above normal for all participants. No patient showed signs of papilledema by ophthalmoscopy.

The CT of the brain was normal in all patients, without atrophy, peri-ventricular edema, or dilation of the ventricular system. While patients were awake, the ICP was elevated (>15 mm Hg) and significantly higher in the morning than in the evening (20.7 ± 0.8 mm Hg vs 17.7 ± 0.5 mm Hg; p<0.02 by paired

DISCUSSION

The present study has shown (1) that awake values for ICP are pathologically elevated in patients with severe OSA, (2) that the ICP increases further during sleep, especially NREM stages 2 to 3 and REM sleep related to the apneic episodes, and (3) strong correlations between durations of apnea and AP and ICP elevations and between AP variations and ICP elevations.

Elevations in ICP related to respiration, especially Cheyne-Stokes respiration, are well known.7 Elevations in ICP during OSA have

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    Manuscript received February 5; revision accepted May 24.

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    Copyright © 1989 The American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.