Blood pressure changes after automatic and fixed CPAP in obstructive sleep apnea: relationship with nocturnal sympathetic activity

Treatment of obstructive sleep apnea (OSA) by continuous positive airway pressure (CPAP) usually causes a reduction in blood pressure (BP), but several factors may interfere with its effects. In addition, although a high sympathetic activity is considered a major contributor to increased BP in OSA, a relationship between changes in BP and in sympathetic nervous system activity after OSA treatment is uncertain. This study was undertaken to assess if, in OSA subjects under no pharmacologic treatment, treatment by CPAP applied at variable levels by an automatic device (APAP) may be followed by a BP reduction, and if that treatment is associated with parallel changes in BP and catecholamine excretion during the sleep hours. Nine subjects underwent 24-h ambulatory BP monitoring and nocturnal urinary catecholamine determinations before OSA treatment and 2 months following OSA treatment by APAP (Somnosmart2, Weinmann, Hamburg, Germany). Eight control subjects were treated by CPAP at a fixed level. After APAP treatment, systolic blood pressure (SBP) decreased during sleep (p < 0.05), while diastolic blood pressure (DBP) decreased both during wakefulness (p < 0.05) and sleep (p < 0.02). Similar changes were observed in subjects receiving fixed CPAP. Nocturnal DBP changes were correlated with norepinephrine (in the whole sample: r = .61, p < 0.02) and normetanephrine (r = .71, p < 0.01) changes. In OSA subjects under no pharmacologic treatment, APAP reduces BP during wakefulness and sleep, similarly to CPAP. A reduction in nocturnal sympathetic activity could contribute to the reduction in DBP during sleep following OSA treatment.     

Blunted nighttime blood pressure dipping in postmenopausal women

Blunting of the normal drop in blood pressure (BP) from day to night is emerging as a strong prognostic indicator of cardiovascular morbidity and mortality. This study evaluated the effects of natural menopause on BP dipping in African American and white women. A total of 112 women (62 premenopausal and 50 postmenopausal) took part in the study. Pre- and postmenopausal groups were comparable in terms of clinic BP, body mass index, and ethnic composition. Ambulatory BP was recorded over 24 h during a typical workday, with measurements programmed to be taken every 15 min during waking hours and every 30-minutes during sleeping hours. Nocturnal BP dipping was defined as the difference between waking and sleep BP. Waking BP did not differ by menopausal status. However, nocturnal systolic BP (SBP) and diastolic BP (DBP) dipping were attenuated in postmenopausal women, with both SBP (P < .05) and DBP (P < .05) higher during nighttime sleep in postmenopausal than in premenopausal women. Ethnicity was also related to BP dipping, with African American women tending to show blunted SBP dipping (P = .055) compared with white women; BP dipping was most blunted in postmenopausal African American women. These observations suggest that blunted nighttime BP dipping may contribute to increased cardiovascular disease risk in postmenopausal women.     

Nighttime blood pressure and nocturnal dipping are associated with daytime urinary sodium excretion in African subjects

Blood pressure (BP) follows a circadian rhythm, with 10% to 15% lower values during nighttime than during daytime. The absence of a nocturnal BP decrease (dipping) is associated with target organ damage, but the determinants of dipping are poorly understood. We assessed whether the nighttime BP and the dipping are associated with the circadian pattern of sodium excretion. Ambulatory BP and daytime and nighttime urinary electrolyte excretion were measured simultaneously in 325 individuals of African descent from 73 families. When divided into sex-specific tertiles of day:night ratios of urinary sodium excretion rate, subjects in tertile 1 (with the lowest ratio) were 6.5 years older and had a 9.8-mm Hg higher nighttime systolic BP (SBP) and a 23% lower SBP dipping (expressed in percentage of day value) compared with subjects in tertile 3 (P for trend <0.01). After adjustment for age, the SBP difference across tertiles decreased to 5.4 mm Hg (P=0.002), and the SBP dipping difference decreased to 17% (P=0.05). A similar trend across tertiles was found with diastolic BP. In multivariate analyses, daytime urinary sodium and potassium concentrations were independently associated with nighttime SBP and SBP dipping (P<0.05 for each). These data, based on a large number of subjects, suggest that the capacity to excrete sodium during daytime is a significant determinant of nocturnal BP and dipping. This observation may help us to understand the pathophysiology and clinical consequences of nighttime BP and to develop therapeutic strategies to normalize the dipping profile in hypertensive patients.     

Is the nocturnal fall in blood pressure reduced in essential hypertensive patients with metabolic syndrome?

OBJECTIVE: The aim of this study was to examine whether an impaired reduction in nocturnal blood pressure (BP), defined on the basis of two periods of ambulatory BP monitoring (ABPM), is present in hypertensive patients with metabolic syndrome, as defined by the NCEP criteria. METHODS: 460 grade 1 and 2 untreated essential hypertensives (mean age 45.9 +/- 11.9 years) referred for the first time to our outpatient hospital clinic underwent the following procedures: 1) medical history and physical examination; 2) repeated clinic BP measurements; 3) routine examinations; 4) ABPM over two 24-hour periods within 4 weeks. Metabolic syndrome was defined as at least three of the following alterations: increased waist circumference, increased triglycerides, decreased HDL-cholesterol, increased BP, or high fasting glucose. Nocturnal dipping was defined as a night-time reduction in average SBP and DBP >10% compared to average daytime values. RESULTS: The 135 patients with metabolic syndrome (group I) were similar for age, gender and known duration of hypertension to the 325 patients without it (group II). There were no significant differences between the two groups in average 48-hour, daytime, night-time SBP/DBP values and the percentage nocturnal SBP and DBP decrease (-17.7 / -15.7 vs. -18.4 / -16.2, p = ns). A reproducible nocturnal dipping (decrease in BP >10% from mean daytime in both ABPM periods) and non-dipping profile (decrease in BP < or =10% in both ABPM periods) was found in 74 (54.8%) and 29 (21.4%) in group I and in 169 (52.1%) and 73 (22.4%) in group II, respectively (p = ns); 32 patients (23.7%) in group I and 83 patients (25.5%) in group II had a variable dipping profile (p = ns). CONCLUSIONS: This study shows that no significant difference exists in nocturnal BP patterns, assessed by two ABPMs, in untreated essential hypertensive patients with metabolic syndrome compared to those without it.     

阻塞性睡眠呼吸暂停患者睡眠时高血压的发生

目的明确阻塞性睡眠呼吸暂停综合征（ＯＳＡＳ）患者清醒及睡眠时血压变化情况及对其影响的相关因素。方法１３例ＯＳＡＳ患者在桡动脉内留置导管监测血压并同步进行夜间睡眠多导生理仪连续记录，部分患者观察吸氧或经鼻（面）罩持续正压通气（ＮＣＰＡＰ）的治疗效果。结果（１）ＯＳＡＳ患者白天高血压发生率为４６％（６／１３）；白天无高血压的患者夜间一过性高血压发生率为８６％（６／７）；（２）ＯＳＡＳ患者夜间血压增高与低氧血症和呼吸暂停时间有关，与呼吸暂停指数（ＡＩ）无相关性（Ｐ＞０．０５）；（３）２例ＯＳＡＳ患者经吸氧治疗后，夜间血压波动仍存在，高血压未得到纠正；４例ＯＳＡＳ患者经ＮＣＰＡＰ治疗后，夜间血压波动消失。结论白天无高血压的ＯＳＡＳ患者夜间可反复出现一过性血压增高；ＯＳＡＳ患者夜间血压增高与低氧血症、呼吸暂停时间有关，但低氧血症不是引起夜间血压增高的主要因素；单纯吸氧不能纠正ＯＳＡＳ患者夜间血压增高，ＮＣＰＡＰ是纠正ＯＳＡＳ患者夜间血压增高的较好方法。     

Ambulatory blood pressure monitoring in patients with hyperthyroidism before and after control of thyroid function

BACKGROUND AND OBJECTIVE: Thyroid hormones have pronounced effects on the cardiovascular system. Thyrotoxicosis affects blood pressure (BP), modifying both diastolic (DBP) and systolic (SBP) pressures. There are no studies examining BP with ambulatory blood pressure monitoring (ABPM) in hyperthyroidism before and after control of thyroid function. Our aims were (1) to analyse ABPM in a group of normotensive hyperthyroid patients before and after normalizing circulating thyroid hormones and (2) to compare these results with those obtained in a group of euthyroid subjects. PATIENTS AND MEASUREMENTS: We studied 20 normotensive hyperthyroid subjects [18 women; age (mean +/- SEM) 49.0 +/- 3.0 years] and 15 healthy subjects. Patients were evaluated by ABPM over 24 h, at diagnosis and after therapy (n = 18). RESULTS: The average 24-h, daytime and night-time SBP was significantly greater in hyperthyroid patients than in controls with no significant differences in DBP. Circadian BP rhythm, estimated by the difference between mean values of SBP, DBP and mean BP during daytime and night-time, was unchanged. The average 24-h and daytime SBP significantly decreased after normalizing thyroid function in the 18 hyperthyroid evaluated patients. Daytime SBP and DBP were higher than night-time values both before and after control of thyroid function. However, no differences in circadian BP rhythm were observed. CONCLUSIONS: Normotensive hyperthyroid patients exhibit higher ambulatory SBP throughout 24 h than normotensive euthyroid subjects. Control of hyperthyroidism decreases ambulatory SBP values. Mean nocturnal fall in BP is comparable in normotensive hyperthyroid patients and control subjects.     

Twenty-four-hour ambulatory blood pressure in children with sleep-disordered breathing

Obstructive sleep apnea causes intermittent elevation of systemic blood pressure (BP) during sleep. To determine whether obstructive apnea in children has a tonic effect on diurnal BP, 24-hour ambulatory blood pressure was obtained from 60 children with mean age of 10.8 +/- 3.5 years. Thirty-nine children had obstructive apnea and 21 had primary snoring. Children with obstructive apnea had significantly greater mean BP variability during wakefulness and sleep, a higher night-to-day systolic BP, and a smaller nocturnal dipping of mean BP. Variability of mean arterial pressure during wakefulness was predicted by the desaturation, body mass, and arousal indices, whereas variability during sleep was predicted by apnea-hypopnea and body mass indices. Nocturnal BP dipping was predicted by the desaturation index. There were no significant differences in systolic, diastolic, or mean arterial BP during sleep between the groups. Diastolic BP during wakefulness was significantly different between the groups and correlated negatively with apnea-hypopnea index. We conclude that obstructive apnea in children is associated with 24-hour BP dysregulation and that, independent of obesity, the frequency of obstructive apnea, oxygen desaturation, and arousal contributes to abnormal BP control.     

Determinants of the Awakening Rise in Systemic Blood Pressure in Obstructive Sleep Apnea Syndrome

To investigate the factors responsible for the morning rise in blood pressure (BP) in obstructive sleep apnea syndrome (OSAS) we examined a group of 253 consecutive snorers or OSAS patients. On the basis of their AHI the patients were classified in four groups. BP was measured on the evening before sleep onset and on the following morning after 15min of rest by a finger arterial pressure device (Finapres). In 150 subjects BP was monitored during the night by a Finapres device. In the morning BP increased in the patient group with an average difference of 9.9 0.5 mmHg for systolic (SBP) and 9.9 0.4 mmHg for diastolic pressure (DBP). The increase was significant in snorers and OSAS patients without differences between groups. The morning rise in SBP was related to diurnal values of SBP, age and AHI whereas the time spent in apnea and the diurnal values of DBP significantly contributed to the DBP increase. In the subgroup of 150 patients in whom BP was analyzed during sleep, the awakening increase was related to the absolute BP value during sleep and to the BP changes from wakefulness to sleep. The magnitude of the BP changes from evening to morning was not dependent on the degree of BP variability during sleep. We conclude that the awakening increase in BP in patients with snoring or OSAS may be mediated by the setting of pressure response to apnea or to mechanical effort during sleep. Anthropometric variables and diurnal cardiovascular setting may play an additional role in modulating the final pressure response to upper airway obstruction.     

Nighttime blood pressure dipping in postmenopausal women with coronary heart disease

BackgroundBlunted nighttime blood pressure (BP) dipping is prognostic of cardiovascular morbidity and mortality. This relationship may be stronger among women than men. The present study hypothesized that coronary artery disease (CAD) and advancing age would be associated with reduced BP dipping in postmenopausal women. The effects of daytime physical activity and nighttime sleep quality on BP dipping were also examined.Methods54 postmenopausal women with CAD (≥50% occlusion of at least one major coronary vessel) and 48 age-matched (range 50-80 years) postmenopausal women without CAD (non-CAD) underwent 24-h ambulatory BP monitoring and actigraphic evaluations of daytime physical activity and nighttime sleep efficiency.ResultsWomen with CAD evidenced higher nighttime systolic BP (SBP) (P = 0.05) and blunted SBP dipping (P = 0.017), blunted diastolic BP (DBP) dipping (P = 0.047), and blunted pulse pressure dipping (P = 0.01), compared to non-CAD women. Multivariable regression models showed that the presence of CAD, age, daytime physical activity, and nighttime sleep efficiency were independently related to the magnitude of SBP dipping, together accounting for 25% of its variability. DBP dipping showed similar associations.ConclusionsFor postmenopausal women, the presence of CAD and advancing age are accompanied by blunted nighttime BP dipping, which may increase the risk of adverse cardiovascular events. Lifestyle changes that increase daytime physical activity and improve nighttime sleep quality may help improve cardiovascular risk by enhancing nighttime BP dipping.American Journal of Hypertension 2012; doi:10.1038/ajh.2012.95.     

Reproducibility of blood pressure variability, white-coat effect and dipping pattern in untreated, uncomplicated and newly diagnosed essential hypertension

OBJECTIVE: To investigate the reproducibility of blood pressure (BP) variability, white-coat effect (WCE) and nocturnal dipping pattern in untreated patients with uncomplicated essential hypertension using 24-hour ambulatory BP monitoring (ABPM). METHODS: Seventy-five newly diagnosed, untreated essential hypertensive subjects (54 men, 21 women 47.6 +/- 9.3 years) were recruited for the study based on conventional measured BP from a total of 180 patients referred for ABPM. Of these, 65 patients underwent repeated ABPM after 4 weeks observation without treatment. Reproducibility of BP, nocturnal dipping pattern, WCE and BP variability were assessed using different methods. RESULTS: The average 24-hour BP (140.8 +/- 11.9/91.8 +/- 6.4 vs. 140.5 +/- 14.5/90.7 +/- 7.6 mmHg, ns) or PP (49.6 +/- 10.8 vs. 49.8 +/- 9.8 mmHg, ns) did not change, nor did daytime BP or PP. The WCE diminished significantly during the observation period (reduction in SBP WCE delta8.2 +/- 12.5 mmHg, p < 0.0001, in DBP WCE, delta3.3 +/- 9.2 mmHg, p = 0.008 and in PP WCE delta4.8 +/- 11.2 mmHg, p = 0.002). Variability in SBP, DBP and PP decreased consistently and significantly during the observation period. The nocturnal dipping pattern was unchanged in 82% of the patients. In 12% non-dipping pattern was converted to dipping pattern after repeated measurement. CONCLUSION: Average ABPs are highly reproducible in patients with uncomplicated essential hypertension of limited duration. Similarly, nocturnal dipping pattern reproduced satisfactorily. These measures have important clinical applicability. The white-coat effect as well as variability are greatly attenuated during repeated measurements, and these measures may thus be of less utility in clinical practice.     

Sources of measurement variation in blood pressure in large-scale epidemiological surveys with follow-up

The Copenhagen City Heart Study (CCHS) is a longitudinal epidemiological study of 19698 subjects followed up since 1976. Variation in blood pressure (BP) measurement in the first three CCHS surveys is evaluated by assessing two components, systematic variation and random variation [daytime and seasonally variation, observer bias, non-response bias, variation with explanatory variables, such as diabetes, hypertension, body mass index (BMI), height, plasma cholesterol and smoking] for the purpose of identifying relevant errors in population surveys. BP was measured in the seated position after a 5 min rest, with the cuff around the non-dominating arm, in accordance with recommended guidelines. The participation rate fell from 74% in survey 1 to 63% in survey 3. Significant non-response bias with respect to BP values was not found. No daytime variability was noted either in systolic (SBP) or diastolic (DBP) BPs. A trend towards a lower BP was seen during the summertime. Random variation, expressed as the standard deviation of the measured values, increased with increasing BP values (SBP: 11.9-13.4 to 21.2- 25.1 mmHg; DBP: 10.6-11.2 to 11.9-13.4 mmHg). SBP was positively correlated to BMI and plasma cholesterol. SBP was 5-10 mmHg higher in diabetics ( p = 0.000-0.04) than in age- and sex-matched nondiabetics. DBP did not differ between the two groups. Smokers from the age of 50 years had a 2-4 mmHg lower SBP ( p = 0.000-0.01) and 1-3 mmHg lower DBP ( p = 0.000-0.005) than had non-smokers. In addition, significantly fewer smokers took antihypertensive medication than did non-smokers ( p = 0.000). In conclusion, judging from the degree of association with BP and/or differences between the three surveys, the most important factors to consider were seasonal variation, BMI, the use of antihypertensive drug therapy, plasma cholesterol, smoking status and diabetes. An inter-survey comparison of BP in population cohorts requires controlling for these factors.     

The effect of 24 h blood pressure levels on early neurological recovery after stroke

OBJECTIVES: To assess the influence of 24 h blood pressure (BP) levels on functional recovery 1 week after stroke and the effect of antihypertensive therapy on 24 h BP levels. DESIGN: Prospective study of patients admitted to hospital over 1 year with first in a lifetime stroke who underwent 24 h BP and casual measurements. Setting. Medical wards in a teaching hospital. Subjects. Of 160 patients, 72 patients admitted to hospital within 24 h of stroke onset were investigated. Patients with conditions and therapy that interfered with autonomic and sympathetic function were excluded. Interventions. All subjects underwent 24 h BP and casual recordings on admission to hospital and at day seven after stroke. The mean 24 h, day and night systolic BP (SBP) and diastolic BP (DBP) and their differences (nocturnal BP dip) were recorded. Patients were divided into three groups according to whether they were taking antihypertensive therapy during the first week: (i) no therapy, (ii) therapy continued after stroke, and (iii) new therapy introduced. Main outcome measures. Functional recovery (Rankin Scale 0-1) and neurological improvement [Scandinavian Stroke Scale (SSS) >/=3 points] by 1 week of stroke. Change in circadian 24 h BP over 1 week. RESULTS: For each 10 mmHg difference between day and night time DBP, the odds for making a complete recovery were 4.63 (95% CI: 1.57-13.7, P=0.01). For each 10 mmHg difference between day and night SBP, the odds for making an improvement in neurological status was 2.24 (95% CI: 1.16-4.32; P=0.016). Significant falls in 24 h DBP (P=0.01), daytime SBP (P=0.005) and mean arterial BP (MABP) (P=0.04) over 1 week were demonstrated in patients who had just commenced antihypertensive therapy (P=0.001). CONCLUSION: An increase in day to night time BP change is favourable in short-term outcome after acute stroke. Significant falls in BP are more likely in patients started on antihypertensive therapy for the first time. Further research is required to understand the effects of circadian BP rhythm on stroke outcome.     

Differences in exercise blood pressure response between dipper and non-dipper elderly patients with essential hypertension

We evaluated the circadian variation and exercise stress response patterns of blood pressure (BP) in elderly patients with essential hypertension. Ambulatory BP monitoring for 48 hours every 30 minutes, and treadmill exercise test using a Bruce protocol at PM 3 to 5 were performed in 49 untreated patients with hypertension. Mean daytime (awake), and night-time (sleeping) systolic BP (SBP) and diastolic BP (DBP) values were analyzed by reviewing the patients' diaries, and the nocturnal reduction rate (NRR) of SBP and DBP were calculated according to the following formula. NRR (%) = [(daytime mean-nighttime mean)/daytime mean] x 100. The patients were divided into two groups according to the presence (dipper, n = 25) or absence (non-dipper, n = 24) of a reduction in both SBP and DBP during the night by an average of more than 10% of the daytime BP. Mean values of SBP and DBP measured over 48 hours in the dipper and non-dipper groups were similar. Responses of SBP to dynamic exercise at 2 to 5 minutes in the non-dipper group were significantly smaller than those in the dipper group (p < 0.05). Non-dipper patients with hypertension responded to dynamic exercise stress with smaller increases in SBP than did those in the dipper group. The differences in BP responses to exercise may affect the circadian blood pressure profile in dipper and non-dipper elderly patients with essential hypertension.     

Upper-airway collapsibility: measurements and sleep effects.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is characterized by repetitive pharyngeal collapse during sleep. Several techniques have been proposed to assess the collapsibility of the upper airway in awake humans, but sleep-wake comparisons have rarely been attempted and there are few studies comparing OSA patients to control subjects. We sought to compare two collapsibility measurement techniques between normal and apneic subjects, and between wakefulness and sleep. DESIGN: We conducted three studies. First, we examined whether collapsibility assessed by negative pressure pulses (NPPs) during wakefulness reflected values during sleep in 21 normal subjects. Second, we determined in these normal subjects whether collapsibility during sleep assessed by NPPs was predictive of collapsibility measured by inspiratory resistive loading (IRL). Finally, we compared upper-airway collapsibility between apnea patients (n = 22) and normal volunteers (n = 38) during wakefulness by NPPs. SETTING: Clinical and research laboratories at the Brigham and Women's Hospital. PARTICIPANTS: Two populations of normal subjects (n = 21 and n = 38) and OSA patients (n = 22). Measurements and results: Collapsibility during wakefulness, as measured by NPPs, correlated significantly with collapsibility during sleep (r = 0.62; p = 0.003). There was also a significant correlation between the two measures of collapsibility (IRL and NPP) during sleep (r = 0.53; p = 0.04). Both measures revealed a significant increase in pharyngeal collapsibility during sleep as compared to wakefulness. Finally, apnea patients had significantly greater pharyngeal collapsibility than control subjects during wakefulness (p = 0.017). CONCLUSIONS: These data suggest that upper-airway collapsibility measured during wakefulness does provide useful physiologic information about pharyngeal mechanics during sleep and demonstrates clear differences between individuals with and without sleep apnea.     

Effect of a single session of aerobic walking exercise on arterial pressure in community-living elderly individuals

Several studies have demonstrated that one exercise session (ES) on a cycloergometer or ergometric treadmill causes a reduction in blood pressure (BP). However, there are few similar studies on walking, which is the exercise modality most available to the elderly. We investigated the immediate and 24-h effects of walking on BP in independent, community-living elderly individuals. Volunteers participated in a single ES and resting control session (CS). Before and after each session, BP was measured by auscultatory and oscillometric methods. After each session, 24-h ambulatory blood pressure monitoring was conducted. An accelerometer was installed 48?h before the sessions and left in place for 5 days. The mean volunteer age was 67.7±3.5 years; 11 were hypertensive patients under treatment, and 12 were normotensive. In the total sample, there were immediate 14mm?Hg and 12?mm?Hg reductions in systolic BP (SBP) after the ES according to the auscultatory and oscillometric methods, respectively. Diastolic BP (DBP) was reduced by 4?mm?Hg after the ES according to both methods. SBP during wakefulness and sleep and DBP during wakefulness were lower after the ES than after the CS (P<0.01), when wakefulness and sleep were determined individually (variable-time pattern) using data from the activity monitors and provided by the volunteers. The variable-time pattern was more effective in detecting reductions in BP than the fixed-time pattern.     

Blood pressures at work, home and during sleep in patients with essential hypertension: analysis by ambulatory blood pressure monitoring

Blood pressure (BP) recordings were obtained every 30 min using a noninvasive ambulatory BP recorder during 24 hours in 93 subjects with hypertension. Recordings were analyzed in four different situations: (1) annual check up at the health service center, (2) at work, (3) at home, and (4) during sleep. Subjects with BP higher than 160/95 mmHg in any of the three situations were defined as established hypertensive (n = 36); Subjects with 140-159/90-94 mmHg, as the borderline hypertensive (n = 32); and subjects with BP lower than 139/89 mmHg, as the normotensive (n = 25). Four successive systolic and diastolic BP values were averaged and served as 24-hour BP patterns. Systolic BP over 140 mmHg, diastolic BP over 90 mmHg and mean BP over 107 mmHg were defined as a s-hyperbaric index (s-HBI), d-HBI and m-HBI, respectively. The normotensive group showed a marked decrease of BP after recordings explained by the "white coat phenomenon". The 24-hour recordings in all the three groups showed the highest BP at work and the lowest during sleep. The situational BP changes were generally similar, but the established hypertensive group showed larger BP differences between work and home (SBP 8.8 +/- 9.0 mmHg, 7.8 +/- 8.3 mmHg). For differentiating the three groups, the hyperbaric index was better than the 24-hour average BP. The average home BP showed a good correlation with the 24-hour average BP [SBP: r = 0.94 (p less than 0.01), DBP: r = 0.85 (p less than 0.01)]. Especially, BPs recorded before sleep predicted well the 24-hour average BP. An average of multiple BP measurements before sleep is thought to represent a 24-hour average BP more closely than a conventionally used single recording at home or after awakening.     

Twenty-four-hour ambulatory BP in snoring children with obstructive sleep apnea syndrome

INTRODUCTION: Obstructive sleep apnea syndrome (OSAS) is a known risk factor for hypertension in adults. This relationship is less clear in childhood OSAS. OBJECTIVE: This study examined the relationship between OSAS and 24-h ambulatory BP (ABP), a more accurate assessment than casual BP, in children with snoring. METHODS: Snoring children aged 6 to 15 years who underwent polysomnography in the sleep laboratory were recruited. Measurement: Twenty-four-hour ABP monitoring was initiated a few hours before polysomnography. The children were classified into two groups: a high apnea-hypopnea index (AHI) group (obstructive AHI > 5/h), and a low-AHI group (AHI < or = 5/h). Mean sleep, wake, and 24-h systolic BP (SBP) and diastolic BP (DBP) were recorded. A child was considered a "nondipper" if his or her mean SBP and DBP did not decrease by >/= 10% during sleep. RESULTS: Ninety-six children (mean age +/- SD, 9.4 +/- 2.8 years) were recruited. Forty-one children were obese. When awake, the high-AHI group children had a significantly higher SBP. When asleep, both SBP and DBP were higher in the high-AHI group. Age, body mass index (BMI) z score, and desaturation index (DI) were significant predictors for elevated sleep DBP. BMI z score was the only significant predictor for wake and sleep SBP. Sixteen children (17%) had hypertension, and all were nondippers. Obese children in the high-AHI group had a significantly higher prevalence of hypertension than obese children in the low-AHI group. This relationship was not found in nonobese children. CONCLUSION: The current study shows that increased DI contributed to the elevation of sleep DBP elevation.     

Circadian and short-term blood pressure abnormalities after liver transplantation

ABSTRACT

Liver transplantation remains the only therapeutic method in end-stage liver disease. Cardiovascular system diseases, including arterial hypertension, are considered one of the main risk factors increasing mortality in this population. The aim of the study was the evaluation of circadian blood pressure patterns in liver transplant recipients. In a group of 107 liver transplant recipients, a 24-hour ambulatory blood pressure monitoring (ABPM) was performed. The ABPM revealed arterial hypertension in 88.79% and unsatisfactory blood pressure (BP) control in 71.03% of the study participants. The abnormal circadian BP pattern was observed in 90.65% of liver recipients. The subgroup of patients with preserved BP circadian rhythm was characterized by higher standard deviation (SD) and coefficient of variation (CV) values for 24-hour systolic, diastolic and mean arterial blood pressure (SBP, DBP, and MAP). There were no such differences for other short-term blood pressure variability (ST BPV) parameters: SD and CV of day-time and night-time SBP, DBP and MAP values. Arterial hypertension and circadian BP abnormalities are present in a majority of liver transplant recipients. BP circadian rhythm is not associated with ST BPV parameters assessed separately during awake and sleep period which suggests that both groups of parameters could reflect different cardiovascular phenomena after liver transplantation.     

Systolic vs diastolic blood pressure control in the hypertensive patients of the PAMELA population. Pressioni Arteriose Monitorate E Loro Associazioni

BACKGROUND: Previous studies have shown that in the treated fraction of the hypertensive population, blood pressure (BP) control is less common for systolic BP (SBP) than for diastolic BP (DBP) as measured in the physician's office. Whether this phenomenon is artifactually attributable to a temporary increase in BP owing to a "white-coat" effect or represents a true rarity of SBP control in daily life is unknown. METHODS: Data were obtained from the PAMELA (Pressioni Arteriose Monitorate E Loro Associazioni) study population, which involved individuals ranging in age from 25 to 74 years who were representative of the residents of Monza (a city near Milan, Italy) and who were stratified according to sex. Office (an average of 3 sphygmomanometric measurements), home (an average of morning and evening self-measurements using a semiautomatic device), and 24-hour ambulatory (average of measurements performed every 20 minutes during the day and at night) BP values were obtained in all study subjects. In the treated hypertensive patients, BP was regarded as controlled if office values were less than 140 (SBP) or 90 (DBP) mm Hg. Home and 24-hour average SBP and DBP were regarded as controlled if the values were lower than 132/83 and 125/79 mm Hg, respectively. RESULTS: In the study participants (n = 2051), the number of patients with hypertension who were receiving antihypertensive treatment was 398, or approximately 42% of all individuals with hypertension. In-office SBP control by treatment was less frequent than DBP control (29.9% vs 41.5%, P<.05). This was also the case when home and 24-hour SBP and DBP control was considered (38.3% vs 54.6% and 50.8 vs 64.9%, respectively, P<.05 for both). CONCLUSIONS: In the PAMELA population, SBP control by treatment was much less frequent than DBP control by treatment. This was the case not only for office BP values but also for home and 24-hour BP values, demonstrating that inadequate SBP control is not limited to artificial BP-measuring methods but occurs in daily life.     

The influence of work- and home-related stress on the levels and diurnal variation of ambulatory blood pressure and neurohumoral factors in employed women.

The purpose of this study was to examine the effects of self-reported perceived stress at work and home on the levels, variation and co-variation of ambulatory blood pressure (BP), pulse rate (PR) and urinary catecholamine, cortisol, and aldosterone excretion measured at work, home and during sleep in women employed outside the home. The subjects of the study were 134 women (mean age 34.4 +/- 9.6 years, range 18 to 64 years) who were employed in managerial, technical or clerical positions at the same work place. Perceived stress at work and home was self-reported on a scale from 0 (low) to 10 (high). BP, PR and the urinary rates of excretion of epinephrine, norepinephrine, cortisol and aldosterone were averaged in the daily work environment from 11 AM to 3 PM, in the daily home environment from approximately 6 PM to 10 PM, and during sleep from approximately 10 PM to 6 AM the following morning. The results showed that systolic and diastolic BP (SBP and DBP) and the rates of urinary catecholamine, cortisol, and aldosterone excretion measured in the work environment were significantly higher than corresponding measurements taken in the home environment. SBP measured at work was also positively correlated with the difference in perceived stress between work and home (p < 0.05). PR (p < 0.001) and the rate of urinary norepinephrine excretion (p < 0.05) measured in the home environment were positively correlated with stress at home. When the subjects were divided into groups based on whether the work or home environment was perceived to be most stressful, women reporting greater stress at work (n=85) had higher work SBP (p < 0.005), work DBP (p < 0.05), and sleep SBP (p < 0.005) than women who perceived the home environment to be more stressful (n=34). There were no differences in the urinary hormonal excretion rates between these perceived-stress groups. Among women with greater perceived stress at home, the home-stress score was positively correlated with sleep SBP level (r = 0.310, p < 0.05), its variation (SD of sleep SBP: r = 0.402, p < 0.01) and home pulse rate ( r= 0.414, p < 0.01). These findings suggest that among employed women, work stress may increase ambulatory BP levels throughout the day, while home stress may induce additional sympathetic activation at home. In addition, they also show that among employed women who perceive greater stress at home than at work, higher home stress levels may also elevate sleep BP levels.