Causes and consequences of a non-dipping blood pressure profile

The development and clinical application of ambulatory blood pressure monitoring (ABP M) has brought several of the main features of the circadian blood pressure (BP) rhythm to light. ABP M has shown to be a very useful method in cardiovascular risk assessment and remains the only method of diagnosing a non-dipping blood pressure profile. A 'non-dipping' BP profile is currently regarded as a risk factor in its own right for cardiovascular (CV) events and target organ damage. Nevertheless, the reliability of ABP M in assessing dipping status is still being questioned. Furthermore, a clear-cut definition of 'non-dipping' has not been established so far. The pathophysiological mechanism(s) of a non-dipping profile might involve abnormalities in extracellular volume and/or vascular resistance regulation. In addition, differences in daytime and nighttime activity, sleep quality and body position during sleep are involved as well. A reduction in cardiovascular risk by a pharmacologically induced switch from a non-dipper to a dipper status might be expected, but remains to be proven.     

Poor sleep is responsible for the impaired nocturnal blood pressure dipping in elderly hypertensive: A cross-sectional study of elderly

Objective: This study was aimed to assess whether sleep disorder was associated with an increased risk of less nocturnal blood pressure (BP) dipping in elderly patients with hypertension.

Methods: Cases were 1006 patients, aged >60 years, who were admitted to hospital with diagnosed hypertension during 2016–2017, and were divided into three groups with the systolic nocturnal BP dipping of 10%, and 0% as the cut-off value. The patients’ sleep was evaluated by Pittsburgh sleep quality index (PSQI).

Results: Compared to non-dipper BP rhythm patients (n = 382) and dipper BP rhythm patients (n = 132), reverse dipper patients (n = 492) exhibited higher PSQI score and had higher scores on six components with the exception of use sleep drug (p < 0.05). Multivariate logistic regression indicated that poor sleep, which was defined as high score of PSQI or its seven components, was associated with prevalence of reverse dipper in elderly hypertensive (odds ratio (OR) = 1.17, (95% confidence interval (CI), 1.13–1.21, p < 0.05) after adjusting for risk factors of hypertension. Multiple linear regression analysis showed that there was a significant negative correlation between PSQI score (include its seven components) and nocturnal BP dipping value after adjusting for risk factors of hypertension (β = ?0.584, p < 0.001).

Conclusions: In elderly patients with hypertension, poor sleep quality individuals were more prone to reverse dipper BP rhythm. Even adjusting for the effect of known risk factors of hypertension, poor sleep may contribute to attenuated BP dipping in elderly hypertensive.     

Association between HIV infection and attenuated diurnal blood pressure rhythm in untreated hypertensive individuals*

Objective

Hypertensive cardiovascular complications are more closely associated with ambulatory blood pressure (ABP), particularly the attenuated diurnal blood pressure (BP) rhythm (i.e. a fall in systolic blood pressure <10% during the night compared with the day), than with casual BP. The aim of the study was to assess the ABP pattern in an HIV‐infected cohort in which hypertension was newly diagnosed.

Methods

ABP over 24 h was compared between 77 newly diagnosed, untreated hypertensive HIV‐positive individuals and 76 HIV‐uninfected untreated hypertensive controls.

Results

More HIV‐infected subjects had an attenuated ABP rhythm with a reduced nocturnal fall than HIV‐negative hypertensive control subjects (60 vs. 33%, respectively; P=0.001). The dipping pattern was observed despite newly diagnosed hypertension, a low prevalence of microalbuminuria, and the absence of signs of overt kidney disease. Furthermore, the prevalence of nondipping in the HIV‐infected subjects was independent of combination antiretroviral treatment. Multiple logistic regression analysis with dipping pattern as the dependent variable showed that HIV status was an independent predictor of nondipping BP [P=0.002; odds ratio (OR) 0.33; 95% confidence interval (CI) 0.17–0.66]; casual SBP (P=0.37; OR 1.001; 95% CI 0.99–1.04) and microalbuminuria (P=0.39; OR 1.56; 95% CI 0.57–4.28) were not associated with dipping pattern.

Conclusions

The prevalence of a nondipping BP pattern in HIV‐infected subjects with newly diagnosed hypertension who had not received antihypertensive treatment was high and significantly greater than in hypertensive control subjects.     

Stress, menopausal status and nocturnal blood pressure dipping patterns among hypertensive women

BACKGROUND:

A less than 10% decline in blood pressure during the night is known as a nondipping blood pressure (BP) pattern. Nondipping BP has been shown to be associated with target organ damage and poorer cardiovascular outcomes. Additionally, some evidence suggests that hypertensive nondipping women are at greater risk for target organ damage than hypertensive nondipping men.

OBJECTIVE:

To determine whether stress, demographics, menopausal status or sleep quality are associated with nondipping BP among hypertensive women.

METHODS:

A cross-sectional study design was used to describe the relationship between stress and dipping status among a sample of hypertensive women and to describe the sample by age, ethnicity, marital status, menopausal status, current medications and sleep quality.

RESULTS:

The study sample consisted of 47 women (mean [± SD] age 57±13.9 years) with essential or office hypertension who underwent 24 h ambulatory BP monitoring, and completed stress and sleep quality measurements. Thirty-one women (66%) were classified as dippers and 16 (34%) were classified as nondippers. Nondippers were older (P=0.04), postmenopausal (P=0.003) and had lower stress scores (P=0.02) than their dipper counterparts. Postmenopausal status significantly predicted nondipping (OR 16; 95% CI 1.9 to 136.4).

CONCLUSION:

These findings were of interest given that some women had a nondipping BP pattern and significantly lower stress scores. It is possible that there are fundamentally different physiological mechanisms that explain this nondipping phenomenon. In the future, the identification of specific hemodynamic mechanisms associated with nondipping could potentially influence the choice of antihypertensive treatment regimens for nondipper hypertensive patients.     

Physical activity, dipping and haemodynamics

OBJECTIVE: To determine the effect of physical activity on diurnal blood pressure (BP) and haemodynamic variation. METHODS: Ambulatory measurements were performed during 24 h in 36 subjects (18 hypertensive, 13 male), aged 49.7 +/- 13.5 years. BP was recorded in the brachial artery. Physical activity and posture were measured with five acceleration sensors. RESULTS: Of the subjects 50% were dippers (nocturnal decrease in systolic or diastolic BP >/= 10%). Dippers and non-dippers had similar daytime BP, daytime, night-time, and day-night difference in physical activity, subjective sleep quality, and nocturnal cardiac output decrease (14.9 +/- 9.6 and 16.0 +/- 5.9%). In non-dippers vascular resistance increased from day to night by 9.7 +/- 8.3%, while it remained unchanged (-1.0 +/- 13.9%) in dippers. Day-night changes in heart rate and cardiac output were correlated with day-night changes in physical activity (r = 0.39 and 0.43), whereas day-night changes in systolic BP were correlated with night-time activity (r = -0.34). By selection of the active (i.e. walking) and inactive (i.e. not walking) periods during the day, we showed that physical activity has a large potential effect on dipping status and diurnal haemodynamic variation underlying BP variation. Depending on the BP taken (systolic or diastolic, respectively) the proportion of dippers increased to 81% or decreased to 25% if only the walking period was considered, whereas it decreased to 36% or increased to 53% if only the non-walking period was considered. CONCLUSIONS: Non-dippers differ from dippers by an increase of vascular resistance during the night. The degree of physical activity normally encountered during ambulatory monitoring has little influence on the diurnal BP profile or dipping status, but significantly influences underlying haemodynamics. Related to the different effects of posture and activity on systolic and diastolic BP, dipping classification may vary with the BP index taken.     

2型糖尿病患者动态血压特点及分析：附408例动态血压监测结果

了解２型糖尿病患者动态血压特点。方法按有无糖尿病和高血压分组,对４０８例受试者进行２４小时动态血压监测。结果糖尿病伴高血压组平均收缩及收缩压负荷大于平均舒张压及舒张压负荷略小于无糖尿病的原发性高血压组,糖尿病组无论是否伴有高血压,其昼夜血压差值均小于无糖尿病的二组。     

Short-term reproducibility of a non-dipping pattern in type 2 diabetic hypertensive patients

BACKGROUND: Little information is available on the reproducibility of nocturnal variations in blood pressure in type 2 diabetic hypertensive patients. OBJECTIVE: We aimed to compare the intrasubject short-term reproducibility of a nocturnal non-dipping pattern and the prevalence of cardiac and extracardiac signs of target organ damage, in a group of type 2 diabetic hypertensive patients and in an age/gender-matched group of non-diabetic hypertensive subjects. METHODS: Thirty-six treated hypertensive patients with long-lasting type 2 diabetes (> 10 years duration) consecutively attending our hospital out-patient hypertension clinic (group I; mean age, 65 +/- 9 years), and 61 untreated non-diabetic subjects with grade 1 and grade 2 uncomplicated essential hypertension, matched for age and gender, and chosen from patients attending an outpatient clinic (group II; mean age, 65 +/- 5 years), were considered for this analysis. All patients underwent blood sampling for routine blood chemistry, 24-h urine collection for microalbuminuria, two 24-h periods of ambulatory blood pressure monitoring (ABPM) within a 4-week period, echocardiography, and carotid ultrasonography. A dipping pattern was defined as a greater than 10% reduction in the average systolic and diastolic blood pressure at night compared with average daytime values. RESULTS: A reproducible nocturnal dipping and non-dipping profile was found in 11 (30.6%) and 21 (58.3%) diabetic patients, respectively; while only in four (11.1%) patients was a variable dipping profile observed. Of the 23 patients with a non-dipping pattern during the first ABPM period, 21 (91.3%) also had this type of pattern during the second ABPM recording. In group II (non-diabetic hypertensive patients), 30 patients (49.2%, P < 0.05) had a dipping pattern, 13 patients (21.3%, P < 0.01) had a non-dipping profile pattern and 18 patients (29.5%, P < 0.01) had a variable dipping pattern. Of the 20 patients with a non-dipping pattern during the first ABPM period, 13 (65.0%) confirmed this type of pattern during the second ABPM recording. Finally, the prevalence of left ventricular hypertrophy (77.7 versus 41.4%, P < 0.01), carotid plaques (80.5 versus 38.3%, P < 0.01), carotid intima-media thickening (54.3 versus 44.0%, P < 0.05) and microalbuminuria (11.1 versus 2.0%, P < 0.01) was significantly higher in group I than in group II. According to a logistic regression analysis, diabetes, left ventricular hypertrophy and carotid plaques were the main independent predictors of the non-dipping (pattern in the overall population. CONCLUSIONS: These findings indicate that intrasubject variability of non-dipper pattern is lower in diabetic than in non-diabetic hypertensive patients, that classification of diabetic hypertensive patients as dipper or non-dipper on the basis of a single ABP recording is more reliable than in non-diabetic patients, and that the more frequent and reproducible non-dipping (pattern in diabetic patients is associated with a more prominent cardiac and extracardiac target organ damage.     

Circadian rhythm of blood pressure in patients with obstructive sleep apnea.

AIMS: The aims of this study were to examine the circadian variation in blood pressure (BP) in obstructive sleep apnea (OSA) and to compare this between normotensive and hypertensive subjects. METHODS: We measured 24-hour ambulatory BP (ABP) in 72 men (mean age 51 +/- 8 years), with OSA diagnosed on overnight sleep study. Measurements of BP were made at 15 min intervals for 24 h using either an Oxford Medilog ABP or Spacelabs 90207 recorder. All recordings were performed after > or = 3 week washout of anti-hypertensive drugs. The day-time monitoring period was defined as 07:00 hrs to 22:00 and night-time 22:00 to 07:00. The ratio of night:day systolic and diastolic BP was calculated. RESULTS: The patients were obese (mean body mass index 33 +/- 5 kg/m2) with a central pattern of obesity (waist:hip ratio 0.99 +/- 0.14, normal < 0.94). The mean 24-h ABP (systolic/diastolic) was 138 +/- 18/88 +/- 12 mmHg. The mean daytime ABP was 143 +/- 18/93 +/- 12 and night-time ABP 128 +/- 20/80 +/- 12 Hg. The night:day BP ratio was 0.90 +/- 0.07 (systolic) and 0.87 +/- 0.09 (diastolic) indicating that average BP was lower during the night. This pattern was similar in normotensive and hypertensive subjects. In contrast there was a significant relationship between increasing BMI and night:day blood pressure ratio (r = 0.56, p < 0.001) independent of the effects of OSA. CONCLUSION: In contrast to previous studies, men with OSA have a normal diurnal pattern of blood pressure levels. These findings suggest that any influence of OSA on BP is manifested throughout the 24-h period.     

Ethnic differences in sleep quality accompany ethnic differences in night-time blood pressure dipping

BACKGROUND: African Americans exhibit a smaller nocturnal decrease in blood pressure (BP) than whites, and there are also reports of poorer sleep quality among African Americans. We examined the contribution of sleep quality to ethnic differences in BP dipping in African American and white male and female college students. We hypothesized that African Americans would exhibit blunted nocturnal BP dipping compared to whites, which would be partly accounted for by poorer sleep quality among African Americans. METHODS: Forty-three African American and 46 white college students aged 18 to 25 years completed an ambulatory BP protocol that included wrist actigraphy, which was used in conjunction with participant self-reports of sleep times for analyses of sleep quality. RESULTS: Although daytime and night-time BP did not differ according to ethnicity, African Americans had a smaller dip in systolic BP (P < .01), and African American women had a smaller dip in diastolic BP than whites (P < .01). Whites were more likely to be classified as a dipper (71%) than African Americans (41%) (P < .01). African Americans, compared to whites, spent less time in bed, were asleep for a shorter period of time, took longer to fall asleep, exhibited poorer sleep efficiency, and were awakened a higher percentage of the time by the inflation of the BP cuff (F > or = 4.85, P < .05). However, sleep quality did not appear to contribute to ethnic differences in diastolic BP dipping. CONCLUSIONS: Sleep quality accompanied ethnic differences in systolic and diastolic BP dipping, but did not account for these differences.     

Frequency domain of heart rate and blood pressure variability in essential hypertensive patients during sleep: differences between dippers and non-dippers

METHODS: Autonomic nervous function was evaluated by means of power spectral analysis of heart rate and blood pressure variability in dipper (n = 10) and non-dipper (n = 9) essential hypertensive subjects during sleep. The non-dipper subjects were defined as those in whom the nocturnal decrease in blood pressure was < 10% of the daytime blood pressure. We measured beat-to-beat blood pressure by using a Finapres device and all stages of sleep by simultaneous polysomnographic recording during spontaneous nocturnal sleep. We analysed the pattern of changes in blood pressure for random periods of 4 min duration while the patient was awake and during all stages of sleep. For each period (waking, stages 2, 3 and 4 of sleep) a segment of 256 stationary data points was analysed. In the frequency domain, the spectral characteristics of the stationary segments were estimatred by fast Fourier transformation over three frequency bands: low frequency (0.025-0.07 Hz), mid-frequency (0.07-0.14 Hz) and high frequency (0.14-0.35 Hz). RESULTS: Pulse-interval power spectral analysis did not reveal any difference between dippers and non-dippers during waking. In dipper patients, the low-frequency pulse interval (LFPI) decreased during sleep whereas the high-frequency pulse interval increased; the mid-frequency systolic blood pressure and diastolic blood pressure (DBP) decreased significantly and the high-frequency DBP increased during sleep. In non-dipper patients, the LFPI increased from wakefulness to stages 2 and 3 of sleep and the high-frequency pulse interval decreased during sleep; the mid-frequency systolic blood pressure and DBP increased in stage 4 sleep and the high-frequency DBP decreased during sleep. CONCLUSIONS: These findings indicate that non-dipper hypertensive subjects are characterized by increased LFPI and mid-frequency blood pressure during sleep compared with dipper subjects. This alteration in the autonomic nervous function may explain the non-dipper phenomenon in essential hypertension.     

Sleep actigraphy in hypertensive patients with the 'non-dipper' blood pressure profile

Several prospective studies have demonstrated a higher cardiovascular complication rate in patients with a non-dipping compared with a dipping blood pressure profile. However, the extent of blood pressure reduction during sleep can be highly variable in an individual patient, and a repeat ambulatory blood pressure study commonly shows a change in category. The reasons for this variability are not clear. In general, hypertensive patients with a non-dipper blood pressure profile have higher actigraphy-measured activity during time in bed than dipper hypertensive patients but no analysis of actigraphy-determined sleep parameters has been published. We therefore prospectively studied 52 hypertensive patients who were off antihypertensive drugs for at least 3 weeks and who underwent simultaneous ambulatory and wrist actigraphy monitoring. All patients were clinically free of any sleep-related disorder. The blood pressure profile was labelled dipper when the change in mean awake blood pressure to sleep blood pressure was 10% or higher and non-dipper if less than 10%. Overall activity levels were higher during the time in bed in the non-dipper group compared with the dipper group. An inverse relationship of daytime activity with age was seen in men (r = -0.54, P = 0.001) but not in women (r = -0.06, P = 0.79). Both groups of hypertensive patients had a similar total time in bed (458 +/- 92 min, in dippers and 433 +/- 106 min in non-dippers, P = 0.39). Sleep latency (time to onset of sleep after getting into bed) was a median of 7 min in dippers and 15 min in non-dippers (P = 0.10). In addition, dipper hypertensives spent more of the time in bed asleep than non-dippers (87% vs 76%, P = 0.004). Logistic regression analysis revealed that body mass index, kg/m(2) (OR, 1.3), and night-time activity (units/min) (OR, 1.1) were predictive of a non-dipping blood pressure profile. These data show a possible disturbance of sleep in non-dipper hypertensive patients.     

Captopril Administered at Night Restores the Diurnal Blood Pessure Rhythm in Adequately Controlled,Nondipping Hypertensives

The aim of our study was to evaluate whether captopril administered at night, can shift the circadian blood pressure (BP) from a nondipper to a dipper pattern in adequately controlled hypertensive patients, who continued their antihypertensive therapy. In a prospective, randomized, double blind, placebo-controlled designed study, we enrolled 121 treated, adequately controlled nondipping hypertensive patients. All patients were randomly assigned to 12.5 mg captopril or placebo treatment administered at night. In case of nondippers, the dosage of captopril or placebo was doubled after two weeks of treatment, while for dippers antihypertensive regimens were not changed. After another two weeks, all patients underwent ambulatory BP monitoring. Our results show that at the end of the active treatment period, the prevalence of a dipping diurnal BP pattern in the captopril group (70%) was significantly higher than that in the placebo group (9.8%, P < 0.001). Nighttime BP, night/day BP ratio, nighttime BP load and 24-h systolic BP were significantly lower after 4 weeks nighttime captopril treatment compared to baseline. In conclusion, the present study demonstrates for the first time that captopril administered at night can restore the diurnal BP rhythm and decrease the elevated night/day BP ratio in appropriately controlled, nondipper hypertensive patients. These results were mainly due to the decrease of nighttime BP.     

Ambulatory blood pressure level rather than dipper/nondipper status predicts vascular events in type 2 diabetic subjects.

To clarify which parameter, diurnal pattern of blood pressure (BP) or level of BP variability, has the stronger predictive value for fatal and nonfatal vascular events, vital status after a mean (+/-SD) follow-up period of 86+/-46 months was determined in 392 type 2 diabetic subjects without any history of vascular disease, in whom the 24-h BP profile had been monitored between 1988 and 1998. After the exclusion of 28 subjects who died during the follow-up period of causes unrelated to diabetes, 364 subjects were recruited for further analysis. A total of 147 first events, including 50 fatal vascular events and 97 nonfatal vascular events, were recorded during the follow-up period. The rates of various vascular events increased with both reduced nocturnal falls in systolic BP (SBP) and levels of all ambulatory BP parameters. The ambulatory BP parameter showing the largest area under the receiver operating characteristic curve (ROCAUC) for fatal events was the mean 24-h pulse pressure (PP), and that for nonfatal events was the mean nighttime SBP; both exceeded the respective values of nocturnal fall in SBP. Furthermore, when dipper and nondipper diabetic subjects were divided into subgroups based on the 24-h PP (54.3 mmHg) and the nighttime SBP (116.5 mmHg) cut-off points derived from the ROC analyses, Kaplan-Meier plots showed that the diabetic subgroups with high ambulatory BP levels had worse outcomes, independent of dipper/nondipper status. Finally, these parameters were applied to the Cox model with the values of nocturnal fall in SBP and other confounding factors, and results showed that mean 24-h PP and mean nighttime SBP predicted fatal and nonfatal vascular events, respectively, more strongly than nocturnal fall in SBP in type 2 diabetic subjects. These findings therefore suggest that ambulatory BP levels in type 2 diabetic subjects have a higher predictive value for organ damage and death compared with diurnal BP patterns or dipper/nondipper status.     

Ambulatory blood pressure, asymptomatic cerebrovascular damage and cognitive function in essential hypertension

Prolonged exposure to elevated blood pressure (BP) can lead to both structural (white matter lesions (WML) or infarctions) and functional changes in the brain. We studied in previously diagnosed essential hypertensive individuals if diurnal BP variation and ambulatory BP (ABP) profile (daytime, night time and 24-h BP averages) were related to evidence of WML, the presence of 'silent' infarcts, and cognitive performance. A group of 86 patients (mean age 57.4+/-10 years, range 40-80) were first screened for hypertension-related organ damage and underwent 24-h ABP monitoring, magnetic resonance imaging (MRI) of the brain, and a comprehensive neurocognitive assessment. Age and ABP profile were related to more periventricular, but not subcortical, WML and to presence of lacunar infarctions on MRI. After correction for demographical group differences, no association was found between night time dipping of BP on the one hand and both WML load and cognitive parameters (verbal memory, sensorimotor speed, cognitive flexibility) on the other. The presence of lacunar infarctions, however, predicted lower performance on verbal memory. Furthermore, daytime and 24-h pulse pressure averages were associated with pWML, whereas systolic BP and mean arterial pressure (MAP) for daytime, night-time and 24-h periods were higher in patients with lacunar infarctions. Notwithstanding the large variability of WML in this sample, the evidence of a connection between diurnal BP variation and early target organ damage in the brain was not convincing. However, the ABP profile may be predictive of cerebral lesion type.     

Reproducibility study of nocturnal blood pressure dipping in patients with high cardiovascular risk

It has been shown that in most people there is a physiological reduction in blood pressure during nighttime sleep, it falling by approximately 10% compared to daytime values (dippers). On the other hand, in some people, there is no nighttime reduction (non‐dippers). Various studies have found an association between being a non‐dipper and a higher risk of cardiovascular disease, but few have assessed whether the nocturnal pattern is maintained over time. From the database of the TAHPS study, data were available on 225 patients, each of whom underwent 24‐hour ambulatory blood pressure monitoring (ABPM) on four occasions over a period of 5 months. We studied the reproducibility of the nocturnal BP dipping pattern with mixed linear analysis and also calculated the concordance in the classification of patients as dippers or non‐dippers. The intraclass correlation coefficients between the different ABPM recordings were 0.482 and 0.467 for systolic and diastolic blood pressure, respectively. Two‐thirds (67%) and 70% of the patients classified, respectively, as dippers or non‐dippers based on systolic and diastolic blood pressure readings in the first ABPM recording were found to have the same classification based on the subsequent recordings. We conclude that the reproducibility of nocturnal dipping patterns and concordance of dipper vs non‐dipper status in individual patients is modest and therefore that we should be cautious about recommending treatments or interventions based on these patterns.     

Reproducibility of ambulatory blood pressure monitoring in daily practice.

The reproducibility of ambulatory blood pressure monitoring (ABPM) was investigated in 45 untreated hypertensive patients in an out-patient clinic. Subjects with symptoms or diseases which could probably give rise to an increase in blood pressure (BP) variability were excluded. Patients underwent office BP (OBP) measurements and ABPM measurements with the Oxford Medilog device twice. The data were edited following previous set standards. Reproducibility of ABPM was good for the group: 24 h ABPM difference 0/2 mm Hg, standard deviation of the difference (SDD) 12/6 mm Hg for systolic BP and diastolic BP respectively. For OBP the difference between the two visits was 5/2 mm Hg with a SDD of 15/8 mm Hg. Intra-individual reproducibility was poor; almost half of the patients had a systolic difference of more than 10 mm Hg between both ABPM recordings. Reproduciblity of the day-night difference with a BP fall of at least 10% (dipper status) was moderate. About 60% of the subjects were dippers at one of the ABPM recordings but only 42% had a reproducible dip. Possible factors playing a role in the disappointing reproducibility of the ABPM recordings are the difference in daily activities between both recording days, decreased accuracy at higher BP, quality of sleep and the probable lower accuracy of the device during real ambulant conditions. In daily practice ABPM has no better reproducibility than OBP measurements, despite the larger number of measurements.     

24 h rhythm of blood pressure and forearm peripheral resistance in normotensive and hypertensive subjects confined to bed

OBJECTIVES: To define whether a diurnal rhythm of peripheral resistance exists in normotensive and hypertensive subjects, has any relationship with that of blood pressure and differs in dipper and non-dipper hypertensives. DESIGN AND METHODS: Forty-three subjects (13 normotensives and 30 mild-to-moderate essential hypertensives) confined for 24 h to bed were included. Blood pressure was recorded for 22 h at 15 min intervals, plethysmographic forearm flow was simultaneously measured and forearm resistance calculated. The analysis was performed for the whole 22 h period and for three 4 h truncated periods, two of certain wakefulness and one of certain sleep. RESULTS: A circadian rhythm of forearm resistance was shown in the normotensives, paralleling that of blood pressure. All the normotensives were dippers, with a nocturnal blood pressure dip (systolic/diastolic) of -4.5/-6.0%. In the hypertensives, the day/night blood pressure trends were not homogeneous: 21 showed higher blood pressure values during waking time, with a trend quite similar to that of the normotensives, whereas the other nine were non-dippers. Resistance was lower during sleep than during waking both in the normotensives and in the dipper hypertensives, whereas in the non-dippers it was higher during sleep. CONCLUSIONS: A sleep/waking rhythm of peripheral resistance with the highest values during daytime and the lowest during night-time does exist in normotensive as well as in the majority of hypertensive subjects resting continuously in bed, and therefore is largely independent of physical activity. Only in a minority of hypertensive patients are higher values of peripheral resistance present during sleep.     

24-hour BP in children with congenital central hypoventilation syndrome

OBJECTIVE: To study circadian BP patterns in patients with congenital central hypoventilation syndrome (CCHS). DESIGN: Case-control study. SETTING: Teaching hospital in Paris, France. PATIENTS: Eleven patients with CCHS (median age, 13 years; range, 6 to 18 years) and 11 sex- and height-matched control subjects. INTERVENTION: None. METHODS: Each subject underwent 24-h ambulatory BP monitoring. Oxygen saturation and end-tidal PCO(2) were monitored noninvasively. Polysomnography was performed to determine sleep times. All patients with CCHS received mechanical ventilation during sleep. Mean values for systolic BP (SBP) and diastolic BP (DBP) during wakefulness and sleep were analyzed. Nocturnal BP "dipping" was defined as the difference in mean SBP (and/or DBP) between wakefulness and sleep, divided by individual waking mean values. BP "dippers" were defined as subjects showing at least 10% nocturnal dipping. RESULTS: Patients with CCHS had BPs in the low normal range of normative data. As compared to control subjects, patients with CCHS had lower BP during wakefulness (p = 0.003 and p = 0.016 for SBP and DBP, respectively), and higher BP during sleep (p = 0.016 and p = 0.002). Nocturnal BP dipping was abnormally reduced in patients with CCHS (p = 0.000). Ten of the 11 patients with CCHS were BP nondippers, compared to none of the control subjects. CONCLUSION: The abnormal circadian BP pattern observed in children and adolescents with CCHS may be related to autonomic nervous dysfunction. Lifelong cardiovascular follow-up is recommended for patients with CCHS.     

不同血压类型脑梗死患者动态血压参数与动脉硬化指数关系的研究

目的探讨不同血压类型脑梗死患者动态血压参数与动脉硬化指数的关系。方法选择住我院卒中单元病房治疗的265例急性缺血性脑卒中患者,将入选患者分为杓型组80例、非杓型组90例和反杓型组95例。应用美国国立卫生研究院卒中量表评分和Barthel指数评分,对各组入院时和随访3个月的患者行神经功能缺损程度和日常生活能力评估,并评价各组患者改善率、复发率和病死率的差异。结果 3组患者动态血压参数、动态动脉硬化指数(AASI)比较,差异有统计学意叉(P<0.05),反杓型组AASI高于杓型组和非杓型组(P<0.05),脑梗死患者部分动态血压参数与AASI呈正相关(P<0.05),AASI与高敏C反应蛋白呈正相关。随访3个月,反杓型组的改善率低,而病死率高于杓型组和非杓型组(P<0.05)。结论不同血压类型患者AASI不同,反杓型高血压患者动脉粥样硬化病变明显,预后不良。