Clinical Significance of Nocturnal Blood Pressure Monitoring

Although there are certain technical problems in determining nocturnal BP by ambulatory BP monitoring, the information provided on nocturnal BP has possible clinical significance. Short-term BP variability, an elevated BP during sleep and amplitude and sleep of nocturnal BP decline might be responsible for cardiovascular mortality. Furthermore, circadian BP variation might also be responsible for cardiovascular morbidity and mortality. The nocturnal BP level, even in extreme dippers with diurnal hypertension, is equivalent to or higher than that in normotensive subjects. Antihypertensive effects of drugs with different pharmacologic properties positively correlate with basal ambulatory BP. Therefore, there is a critical BP level at which the antihypertensive effect disappears. The critical BP level for each drug is in normal BP range but not in the hypotensive range. Therefore, an antihypertensive regimen would be safe even in extreme-dipper hypertension without excessive nocturnal hypotension, and might even be beneficial because of the decreasing amplitude and speed of the nocturnal BP decline. We conclude that an antihypertensive drug regimen should control BP throughout a 24-h period regardless of circadian BP variation.     

Hypoxemia in patients on chronic opiate therapy with and without sleep apnea

Objective  Animal models have shown a quantal slowing of respiratory pattern when exposed to opioid agonist, in a pattern similar to that observed in central sleep apnea. We postulated that opioid-induced hypoventilation is more likely to be associated with sleep apnea rather than hypoventilation alone. Since we did not have a direct measure of hypoventilation we used hypoxemia as an indirect measure reasoning that significant hypoventilation would not occur in the absence of hypoxemia. Methods  We conducted a retrospective analysis of 98 consecutive patients on chronic opioid medications who were referred for overnight polysomnography. All patients on chronic opioids seen in the chronic pain clinic were referred for a sleep study regardless of whether they had sleep symptoms or not. Sleep-related hypoxemia was defined as arterial oxyhemoglobin saturation of less than 90% for more than 5 min with a nadir of ≤85%, or greater than 30% of total sleep time at an oxyhemoglobin saturation of less than 90%. Results  Of the 98 patients, 36% (95% CI 26–46%) had obstructive sleep apnea, 24%, (95% CI 16–33%) had central sleep apnea, 21% (95% CI 14–31%) had combined obstructive and central sleep apnea, in 4% (95% CI 0–10%) sleep apnea was classified as indeterminate, and 15% (95% CI 9–24%) had no sleep apnea. Opioids were potentially responsible for hypoxemia during wakefulness in 10% of patients (95% CI 5–18%) and for hypoxemia during sleep not clearly associated with apneas/hypopneas in 8% of patients (95% CI 4–15%). Two patients (2%, 95% CI 0–7%) had sleep-related hypoxemia in the absence of sleep apnea or hypoxemia during wakefulness. Conclusions  Patients on chronic opiate therapy for chronic pain have an extremely high prevalence of sleep apnea and nocturnal hypoxemia. Hypoxemia can occur during quiet wakefulness in patients on chronic opioid medications with and without sleep apnea. In patients on chronic opioid therapy, isolated nocturnal hypoxemia without coexisting sleep apnea or daytime hypoxemia is very uncommon.     

Trends in antihypertensive drugs used for elderly patients]

The admission of antihypertensive medications in the elderly (65 y.o. or more, 269 pts) was compared to that in younger cases (less than 65 y.o., 348 pts). All were outpatients who visited our clinic in 1990. The number of patients on a single therapeutic regimen was almost equal in both age groups. Once-a-day regimens were more common in the young (56.9% vs 48.3%, p less than 0.05), and three times-a-day regimens were more common in the elderly (14.7% vs 23.1%, p less than 0.01). The choice of antihypertensive drugs in patients with single therapy or combined therapy in the young was beta blockers in 49.7%, Ca blockers in 39.4%, diuretics in 30.7% and ACE inhibitors in 17.8%, and those in the elderly were Ca blockers in 46.1%, diuretics in 44.2%, beta blockers in 33.8%, and ACE inhibitors in 16.4%. The patients were subdivided into three groups according to the time of the initial visit to the clinic; initial visit during 1969-1979 (phase 1), 1980-1984 (phase 2) and 1985-1990 (phase 3). In the young, choice of beta blockers and diuretics was most popular in phase 1. However, the choice of diuretics decreased in phase 2, and in phase 3 beta blockers were used in 50.4%, Ca blockers in 43.2%, ACE inhibitors in 22.3% and diuretics in only 17.3%. In the elderly, diuretics were most popular followed by Ca blockers and beta blockers in phase 1 and phase 2. In phase 3 Ca blockers were selected in 58.2% followed by both beta blockers and ACE inhibitors in 28.4% then diuretics in 23.9%.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Napping and 24-hour sleep/wake patterns in healthy elderly and young adults.

OBJECTIVE: To examine differences between healthy elderly and young adults in daytime napping, nocturnal sleep, and 24-hour sleep/wake patterns. A second objective was to determine whether elderly subjects with more and less frequent naps differed in their clinical features or nocturnal sleep. DESIGN: Survey by sleep/wake logs and polysomnography. Comparison by age. SETTING: Sleep/wake logs were completed in the subjects' homes. Polysomnographic studies were conducted on an outpatient basis in a sleep and chronobiology research laboratory. SUBJECTS: Convenience samples of forty-five healthy subjects over 78 years of age (21M, 24F) and 33 healthy adults between 20 and 30 years of age (20M, 13F). MAIN OUTCOME MEASURES: Using self-reports, we estimated the frequency and timing of daytime naps; timing, duration, and quality of nocturnal sleep; and 24-hour patterns of sleep and wakefulness. Also polysomnographic sleep measures. RESULTS: Compared to young adults, elderly subjects reported a greater mean number of daytime naps (P = .004), shorter nocturnal sleep with more wakefulness and earlier sleep hours (P less than .003 for each), and a trend for a shorter 24-hour sleep fraction. Among the elderly, more-frequent and less-frequent nappers did not differ in clinical ratings, self-report sleep measures, or polysomnographic measures. There was a trend for more sleep-disordered breathing and periodic limb movements in more frequent nappers. CONCLUSIONS: These findings are consistent with an age-related decrease in amplitude of the circadian sleep propensity rhythm, or with the expression of a semi-circadian (12-hour) sleepiness rhythm. However, we cannot exclude the additional possibility that napping results from lifestyle factors and nocturnal sleep pathologies in a subset of the elderly.     

Clinical significance of nocturnal blood pressure monitoring.

Although there are certain technical problems in determining nocturnal BP by ambulatory BP monitoring, the information provided on nocturnal BP has possible clinical significance. Short-term BP variability, an elevated BP during sleep and amplitude and sleep of nocturnal BP decline might be responsible for cardiovascular mortality. Furthermore, circadian BP variation might also be responsible for cardiovascular morbidity and mortality. The nocturnal BP level, even in extreme dippers with diurnal hypertension, is equivalent to or higher than that in normotensive subjects. Antihypertensive effects of drugs with different pharmacologic properties positively correlate with basal ambulatory BP. Therefore, there is a critical BP level at which the antihypertensive effect disappears. The critical BP level for each drug is in normal BP range but not in the hypotensive range. Therefore, an antihypertensive regimen would be safe even in extreme-dipper hypertension without excessive nocturnal hypotension, and might even be beneficial because of the decreasing amplitude and speed of the nocturnal BP decline. We conclude that an antihypertensive drug regimen should control BP throughout a 24-h period regardless of circadian BP variation.     

Prevalence of high-risk cardiovascular conditions and the status of hypertension management among hypertensive adults 65 years and older in the United States: analysis of a primary care electronic medical records database

This study compared the prevalence of high-risk cardiovascular (CV) conditions, antihypertensive medication treatment patterns, and demographic and clinical characteristics associated with blood pressure (BP) goal attainment between elderly (65 years and older) and nonelderly (younger than 65 years) adults with hypertension. Retrospective cohort study was conducted using an electronic medical record database among patients receiving at least 1 antihypertensive medication. CV risk profiles were assessed by International Classification of Diseases, 9th Revision diagnosis codes. Treatment patterns were assessed by the number of antihypertensive medications prescribed. BP goal attainment was determined by the mean of the last 2 BP readings during 1 year of follow-up. Logistic regression estimated the odds of achieving BP goal. There were 61,355 nonelderly (mean age, 51.8 years) and 47,796 elderly (mean age, 73.2 years) patients in the study. Elderly patients had statistically significant higher levels of isolated systolic hypertension and complicated hypertension. Elderly patients had statistically significant higher levels of prescribing patterns characterized by multiple antihypertensive medications but statistically significant lower levels of BP goal attainment. Age 65 years and older, African American race, body mass index ≥30, and the presence of complicated hypertension were found to be statistically significant factors contributing to a lower likelihood of BP goal attainment. Despite aggressive antihypertensive treatment, elderly patients are less likely to achieve BP goals.     

Contrasting Hemodynamic Mechanisms of Losartan- vs. Atenolol-Based Antihypertensive Treatment: A LIFE Study

BackgroundPharmaceutical differences in central hemodynamics might influence cardiac response to antihypertensive treatment despite similar lowering of brachial blood pressure (BP).MethodsData from all patients with at least two echocardiographic examinations in the Losartan Intervention For Endpoint Reduction in Hypertension (LIFE) echocardiographic substudy (n = 801); high-risk patients on losartan- vs. atenolol-based antihypertensive therapy. Echocardiography was performed annually for 4 years to measure stroke index (SI), heart rate, cardiac index (CI), conduit artery stiffness assessed as pulse pressure/stroke index (PP/SI) and total peripheral resistance index (TPRI).ResultsAtenolol- and losartan-based therapy reduced BP similarly (cumulative difference in mean brachial blood pressure 0.3 mm Hg, P = 0.65). After 4 years the cumulative means of SI and heart rate were 1.8 ml/m(2) higher and 5.7 beats/min lower on atenolol-based treatment, respectively (both P < 0.001). This kept CI below baseline in atenolol-treated patients, whereas in the losartan group CI was unchanged from baseline throughout the study. TPRI was decreased more and remained lower in the losartan group (cumulative difference in mean TPRI 287 dynes/sec(-5)/cm/m(2), P < 0.001). These findings partly explained univariate differences in systolic- and diastolic function indices between the two treatments; fully adjusted losartan was only associated with a smaller left atrial diameter (cumulative mean difference 0.07 cm; 95% confidence intervals, -0.13 to -0.01, P = 0.03).ConclusionsContrasting hemodynamics impacted cardiac response to similar reductions in brachial BP on losartan- vs. atenolol-based therapy. The similar reduction of PP/SI suggests that the antihypertensive regimens used in the LIFE study had comparable effects on arterial stiffness (LIFE study; NCT00338260)American Journal of Hypertension, (2012); doi:10.1038/ajh.2012.81.     

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.     

Short sleep duration and increased risk of hypertension: a primary care medicine investigation

Objectives Compelling evidence from laboratory-based and population-based studies link sleep loss to negative cardiovascular health outcomes. However, little is known about the association between sleep duration and hypertension in primary care health settings, independently of other well controlled clinical and biochemical characteristics. We investigated the association between sleep duration and the prevalence of hypertension adjusting for 21 potential confounding factors in a noncontrolled primary care sample. Methods The sample included 1046 French adults older than 40 years (mean age, 55.5 years), who visited any of the general practitioners of primary care centers in the Paris area. Blood pressure (BP) readings, blood samples and standardized health and sleep questionnaires were performed on each participant. Hypertension inclusion criteria were either high BP measurements (SBP ≥140 μmmHg or DBP ≥90 μmmHg) or the use of antihypertensive medications. Sleep duration was recorded as the self-reported average number of hours of sleep per night during the week. Logistic regressions were performed to test the association between hypertension and sleep duration adjusted for sociodemographic, clinical, biochemical, lifestyle, psychological and sleep disorder covariates. Results Compared to the group sleeping 7 h, individuals sleeping 5 h or less had an increased odds ratio (OR) for the prevalence of hypertension [OR = 1.80, 95% confidence interval (1.06-3.05)], after adjusting for 21 potential confounders which did not markedly attenuate this association. Conslusions Our data provide further epidemiologic evidence that with no specific selection in primary care medicine, usual short-sleep duration increases the risk of hypertension prevalence in adults over 40 years.     

Recognition of actual periods of nocturnal rest from 24-hour heart rate profile

Inability to delineate exactly periods of nocturnal sleep and diurnal wakefulness during 24-hour blood pressure (BP) monitoring causes reporting of erroneous BP values for these periods. We suggested a simple mathematical algorithm for detection of periods of nocturnal rest determined as period of low values of cardiac rhythm using data of BP monitoring itself. AIM: To compare novel method of recognition of periods of sleep with 2 standard techniques: use of fixed time interval between 23 and 7 hours (1), or period of sleep according to patient's diaries (2). Reproducibility of nocturnal BP lowering between two 24-hour intervals during 48-hour blood pressure monitoring was used as a measure of precision of determination of diurnal/nocturnal BP. METHODS: Ambulatory 48-hour BP monitoring was carried out in 33 patients with uncomplicated stage II hypertensive disease. Automatic analysis of BP monitoring data was performed with the use of specially designed computer application. Standard deviation (SD) of differences (SDD) between pairs of nocturnal BP lowering during 48 hours was used as a measure of reproducibility. RESULTS: Reproducibility of values obtained with novel algorithm (SDD for systolic/diastolic BP 6.7/8.2 mm Hg) was substantially better than those obtained with standard methods (1) and (2) (SDD 13.0/14.8 and 13.5/18.3 mm Hg, respectively). CONCLUSION: The proposed method of recognition of the period of nocturnal rest substantially improved precision of automatic analysis of 24-hour BP monitoring.     

Risers and extreme-dippers of nocturnal blood pressure in hypertension: antihypertensive strategy for nocturnal blood pressure

There is increasing evidence that disruption of diurnal blood pressure (BP) variation is a risk factor for hypertensive target organ damage and cardiovascular events. Especially, the risers (extreme non-dippers), who exhibit a nocturnal BP increase compared with daytime BP, have the worst cardiovascular prognosis, both for stroke and cardiac events. On the other hand, extreme-dippers (with marked nocturnal BP falls) are at risk for non-fatal ischemic stroke and silent myocardial ischemia, particularly extreme-dippers complicated with atherosclerotic arterial stenosis and excessive BP reduction due to antihypertensive medication. Extreme-dipping status of nocturnal BP is closely associated with excessive morning BP surge and orthostatic hypertension. Hypertensive patients who have these conditions and exhibit marked BP variations are likely to have silent cerebral infarct and to be at high-risk with regard to future stroke. Individualized antihypertensive medication targeting disrupted diurnal BP variation might thus be beneficial for such high-risk hypertensive patients.     

Sleep disorders in geriatric patients.

The elderly have more organic sleep problems disturbing sleep and contributing to insomnia than younger individuals. The most common disorders afflicting the elderly are obstructive sleep apnea, restless legs syndrome, and nocturnal myoclonus. Poor sleep habits often aggravate or contribute to the ongoing difficulty with sleeping. In the depressed elderly, characteristic EEG changes occur that may help distinguish major depression from pseudodementia; however, it should be considered that pseudodementia may be a harbinger of primary dementia. A careful sleep history and often evaluation by polysomnography are central to the management of sleep problems in the elderly. In conjunction with treatment of any underlying organic sleep disorders, brief administration of short-acting benzodiazepine sedatives for sleep onset insomnia or rapid-acting intermediate half-life benzodiazepines for sleep maintenance insomnia can be quite helpful in the elderly, especially if behavioral techniques also are employed. Elimination of medications, alcohol, and caffeine, which disturb sleep, is also an important part of the treatment approach.     

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.     

Nocturnal blood pressure and cardiovascular disease: a review of recent advances

The accurate measurement, prediction and treatment of high blood pressure (BP) are essential issues in the management of hypertension. Ambulatory blood pressure monitoring (ABPM) has been shown to be superior to clinic BP measurements as ABPM can provide the following important information: (i) the mean BP levels, (ii) the diurnal variation in BP and (iii) the short-term BP variability. Among these parameters, there is increasing evidence that the mean nocturnal BP level is the most sensitive predictor of cardiovascular morbidity and mortality. Furthermore, several studies have shown that less nocturnal BP dipping, defined as less nocturnal BP decline relative to daytime BP, or a high night-day BP ratio was associated with poor prognosis irrespective of the 24-hour BP levels. These findings can be interpreted in at least two ways: namely, high nocturnal BP or less nocturnal BP dipping might be not only a potent risk factor for cardiovascular disease (CVD), but also a marker of pre-existing or concurrent diseases that can lead to nocturnal BP elevation. In this review, we consider the clinical utility of ABPM and in particular focus on the nocturnal BP levels or nocturnal BP dipping as a potent risk factor for CVD. In addition, the clinical management of high nocturnal BP and blunted nocturnal BP dipping with antihypertensive medications is discussed.     

Antihypertensive drug reduction for treated hypertensive patients during the summer

Seasonal winter–summer variation in blood pressure (BP) has been reported, but there are few reports on the reduction of antihypertensive medication during the summer. We aimed to investigate the prevalence and details of drug reduction during the summer among outpatients. Among 667 patients, 90 patients (13.5%) had their medication reduced during the summer. The highest rate of drug reduction was for diuretics (17.5%). The patients whose medications were reduced (Group R) took a larger number of drugs and more frequently took diuretics compared with the subjects whose medications were unchanged (N = 559; with no reduction or increase in drugs, Group UC). Moreover, both the office BP and morning home BP of the patients in Group R were significantly lower compared with those of the patients in Group UC. These results suggest that doctors tend to reduce antihypertensive drugs to avoid an excessive decrease in BP especially in patients receiving combination therapy including diuretics.     

Sleep disturbances in patients with asthma

The prevalence of sleep complaints and sleep disturbances was studied prospectively in 98 consecutive adult asthmatic patients (mean age 45 years, 46% men) attending an out-patient clinic by means of questionnaires and sleep diaries. The results were compared with those from an age- and sex-matched group of 226 healthy individuals. The most common sleep disturbances among the asthmatic patients were early morning awakening (51%), difficulty in maintaining sleep (DMS; 44%) and daytime sleepiness (44%). With decreasing asthma control (i.e. increased number of acute asthmatic attacks) there was an increase of DMS, nocturnal wakefulness, nocturnal breathing problems and bronchodilator inhalations at night. A decrease in estimated sleep time (P less than 0.05) and increase in nocturnal wakefulness (P less than 0.05) was seen with decreasing daytime FEV1--measured as percentage of the predicted value (%FEV1). There was also significant correlation between increasing age and decreasing %FEV1 (P less than 0.01). Among the 26 patients who were only taking one oral bronchodilator, no definite difference regarding sleep quality was found between those treated with theophylline and those taking an oral beta 2-agonist. The prevalence rates of DIS, DMS and daytime sleepiness were about twice as high among the asthmatic patients than in the healthy population. It is concluded that impaired quality of sleep, with disturbed sleep during the night, early morning awakenings and daytime sleepiness, is common among patients with bronchial asthma.     

Perindopril effects on ambulatory blood pressure: relation to sympathetic nervous activity in subjects with diabetic nephropathy

BACKGROUND: Few studies have reported the effect of angiotensin-converting enzyme inhibitors on 24-h blood pressure (BP) and regulation of sympathetic nervous activity in hypertensive patients with diabetic nephropathy. Using ambulatory BP monitoring (ABPM) devices equipped with spectral analysis of heart rate variability, we assessed the effects of perindopril on 24-h BP and autonomic nervous activity in these patients. METHODS: Thirty-four hypertensive patients with non-insulin-dependent diabetic nephropathy underwent ABPM before and after treatment with perindopril (final dose: 4.9 +/- 1.8 mg/d). Simultaneously, spectral analysis was performed to calculate the high frequency components (HF) as a marker of parasympathetic nervous activity, and the low frequency components (LF)/HF ratios as an index of the sympathovagal balance. RESULTS: Perindopril significantly and equally decreased the waking and sleeping BP in the diabetic patients. During the sleeping period, the magnitude of change of mean BP induced by perindopril correlated inversely with the sleeping/waking ratio of mean BP before treatment. However, there was no correlation between these parameters during the waking period. Perindopril decreased both waking and sleeping LF/HF ratios, although no differences in HF components were observed between before and after treatment. CONCLUSIONS: In patients with diabetic nephropathy, perindopril decreased 24-h BP. Spectral analysis suggested that this finding was partially related to inhibited sympathetic nervous activity. During sleeping periods, the BP-lowering effect of perindopril was more pronounced in patients showing no nocturnal decrease in BP. Perindopril may be a potent antihypertensive agent to reduce increased nocturnal BP, a risk factor of target organ damage in these patients.     

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.