Intracranial Pressure and Obstructive Sleep Apnea: Materials and Methods

A 1.2-mm catheter was placed in the radial artery in the nondominant hand after ensuring sufficient circulation in the ulnar artery. A catheter was placed in the superior central vein via the brachial vein. Correct localization was ensured by a normal pressure curve for CVP. An epidural pressure sensor (Plastimed) was placed in the right frontal region and was connected to a pressure transducer (AE 840).
Parametric statistics were used (linear regression analysis and t-test). A value below 0.05 was considered significant (two-sided test). The statistics were computed on the SPSS-PC+ program (SPSS Inc).
The study was registered and accepted by the central university ethical committee. All participants gave written informed consent.
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 t-test) (Table 1). this

The mean number of apneic episodes included for analysis were 309 observations (range, 168 to 409). During sleep, especially NREM stages 2 and 3 and REM sleep, the ICP increased, exceeding values while awake. No NREM sleep stage 4 was observed in any of the patients.
While asleep, all patients developed ICP elevation associated with the episodes of OSA (Fig 1). These pressure elevations were seen synchronously with the apneas, with a frequency from one to two pressure elevations per minute, thereby fulfilling the criteria for intracranial B waves. While the patients were awake, no ICP waves were observed in any of the patients.

Table 1—Clinical Data of Patients

Patient, Sex, Age, yr ApneaIndex* Blood Height, cm/ Pressure, Weight, kg mm Hg ICP, mm Hg
Evening Morning
1, M, 43 >50 185/98 130/80 21/18 23/21
2, M, 42 >48 188/110 120/80 14/12 15/13
3, M, 43 >70 185/115 225/120 15/13 18/15
4, M, 52 >50 182/85 175/85 14/11 15/12
5, F, 44 >50 165/85 135/75 20/19 22/20
6, M, 68 >55 175/88 140/85 22/10 30/23

 

Figure 1. Respiration (inductive plethysmography), tcPo2, tcPco2, CVP, ICP (epidural), and AP during period with severe OSA (case 1).

Figure 1. Respiration (inductive plethysmography), tcPo2, tcPco2, CVP, ICP (epidural), and AP during period with severe OSA (case 1).

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