Intracranial Pressure and Obstructive Sleep Apnea: Results

Intracranial Pressure and Obstructive Sleep Apnea: ResultsSeveral phases could be described in the AP and ICP variations. In the beginning of the apnea, there was a decrease in AP and ICP. During the apnea, ICP increased, associated with decreasing tcPo2 and increasing tcPo2. At the termination of the apnea, there was a steep pressure increase, both in the AP and in the ICP, while CVP varied associated with the respiratory movements.
In all patients, there was a highly significant correlation between the duration of apnea and systolic AP variations (Fig 2 and Table 2), between the duration of apnea and systolic ICP variations (Fig 3 and Table 3), and between systolic AP and ICP elevations. The same correlation was observed for diastolic AP and ICP. The correlations were significant (p<0.0001) for all patients, but the slopes of the apnea-AP curve and of the apnea-ICP curve were different between the patients (Tables 2 and 3). There was a significant association between the slope of the AP variations and the slope of ICP variations during the apneas (r = 0.89; p<0.02).

Maximum diastolic and systolic AP and ICP elevations were significantly higher during NREM sleep stage 1 to NREM stages 2 to 3 and highest during REM sleep (Fig 4 and 5) (p<0.0001; paired f-test). Minimum systolic AP decreased during NREM stages 1 to 3 (p<0.01) and increased to the awake value during REM sleep. Minimum diastolic ICP did not change during NREM sleep but increased during REM sleep.
Although AP decreased during apnea, while ICP was unchanged or increased, the CPP (CPP = AP-ICP) decreased (maximum d[CPP] = -11.2±7.8 mm Hg from baseline; p<0.001) during the apnea.
Rapid-eye-movement sleep was associated with longer apnea and greater pressure variations; however, the slopes of the apnea-AP and apnea-ICP curves were not significantly different during REM sleep than NREM sleep, indicating that REM was not associated with changes in distensibility in the arterial or cerebrovascular system.

Table 2—Regression Lines and Correlation Coefficients for All Six Patients for the Association between Apnea Duration and Systolic AP Elevations during Apnea

Case Regression Line Correlation p Value
1 0.726x+10.2* 0.74 <0.0001
2 0.684x+15.4 0.65 <0.0001
3 0.637x + 25.2 0.57 <0.0001
4 2.375x + 20.1 0.61 <0.0001
5 1.157x + 45.2 0.60 <0.0001
6 0.894x + 23.4 0.73 <0.0001

Table 3—Regression Lines and Correlation Coefficients for AH Six Patients for Association between Apnea Duration and Systolic CP Elevations during Apnea

Case Regression Line Correlation p Value
1 0.7882x + 8.015* 0.62 <0.0001
2 0.6471x + 8.203 0.61 <0.0001
3 0.5529x + 7.088 0.59 <0.0001
4 1.176x +9.756 0.76 <0.0001
5 1.012x + 8.372 0.58 <0.0001
6 0.965x + 7.059 0.81 <0.0001

 

Figure 2. Duration of apnea maximum systolic AP variation during apnea (case 1).

Figure 2. Duration of apnea maximum systolic AP variation during apnea (case 1).

Figure 3. Duration of apnea maximum systolic ICP variation during apnea (case 1).

Figure 3. Duration of apnea maximum systolic ICP variation during apnea (case 1).

Figure 4. Mean maximum and minimum diastolic (DBP) and systolic (SBP) arterial blood pressure during sleep for all patients.

Figure 4. Mean maximum and minimum diastolic (DBP) and systolic (SBP) arterial blood pressure during sleep for all patients.

Figure 5. Mean maximum and minimum diastolic (DICP) and systolic (SICP) intracranial pressure during sleep for all patients.

Figure 5. Mean maximum and minimum diastolic (DICP) and systolic (SICP) intracranial pressure during sleep for all patients.

Category: Sleep Apnea

Tags: durations apnea, hypercapnia hypoxia, intracranial pressure, obstructive sleep apnea