Nocturnal blood pressure during apnoeic and ventilatory periods in patients with obstructive sleep apnoea

Abstract

The exact nature of asleep blood pressure in relation to awake blood pressure is still unclear in patients with obstructive sleep apnoea. This study aimed: 1) to investigate the asleep blood pressure in both apnoeic and ventilatory periods; 2) to determine the diurnal and nocturnal factors correlated with the changes in blood pressure from apnoea to ventilatory periods during sleep.Thirty-two patients, newly diagnosed as moderate to severe obstructive sleep apnoea with a standard nocturnal polysomnography, were enrolled. The blood pressure was monitored by using the noninvasive continuous monitoring method during polysomnographic study.The mean blood pressures in ventilatory periods during nonrapid eye movement (NREM) and rapid eye movement (REM) sleep were 117.517.9 mmHg and 128.8 21.9 mmHg, and those in apnoea periods were 94.515.4 mmHg and 102.719.0 mmHg. The average blood pressure during NREM sleep (103.016.1 mmHg) was higher than the awake blood pressure (97.015.7 mmHg). The blood pressure during REM sleep was greater than that during NREM sleep. The changes in the nocturnal blood pressure from apnoea to ventilatory periods were inversely correlated with the age and nocturnal mean nadir saturation.In conclusion, patients with obstructive sleep apnoea have higher asleep blood pressure than awake blood pressure.

The current state of knowledge about the dipping and non-dipping hypertension

“…Continuous hypoxaemia increases expression of ET A receptor and of preproendothelin in the carotid body, therefore enhance chemoreceptor activity [146]. Changes in mean BP from apnoea to ventilation periods stays in inverse correlation with age [16]. It explains why severe apnoea component of OSA is responsible for non-dipping only in young patients, while sleep disturbances are more meaningful in elderly non-dipping OSA individuals [86].…”

“…There is a significant similarity between mechanism of obesity-induced hypertension and non-dipping causes considered in different studies [37][38][39][40][41]. Pathological factors of increased BP in obese individuals that may play role in impaired nocturnal BP drop include: SNS activation which is suggested as crucial, altered kidney functions, obesity-driven hormones elevation, endothelial dysfunction and vascular structural changes [16]. Moreover, obesity, increased BMI, visceral fat and neck circumference are the most established risk factors for occurrence of obstructive sleep apnoea [42].…”

“…Adapted from reference [109] Sodium sensitive (N = 9) Sodium resistant (N = 14) [132]. The highest nighttime BP reduction occurred in the deepest sleep, which corresponded to 3 and 4 stage of non-rapid eye movement sleep, while during 1, 2 stage of NREM and rapid eye movement (REM) sleep BP was significantly higher [16,132]. Central control of respiratory mechanism and respiration oscillations were also directly associated with nocturnal BP changes [132].…”

“…This physiological change between day and night autonomic nervous system (ANS) activity is connected to suprachiasmaticus nucleus and its ability to generate circadian rhythm [10][11][12]. On the other hand, the non-dipping pattern is connected with disorders and disturbances of the circadian rhythm as well as in situation where effects of regular circadian rhythm are too weak to manifest in front of existing pathology [12][13][14][15][16][17][18][19][20][21].…”

Influence of sampling interval on the evaluation of nocturnal blood pressure in subjects with and without obstructive sleep apnoea

“…These findings may be explained by the fact that BP variability does not depend only on the number, but also on the amplitude of BP swings. In fact, a large intersubject variability was shown in the amplitude of BP swings associated with apnoeic episodes, possibly related to factors such as age or Sa,O 2 fall [22].…”