Causes and mechanisms of nondipping hypertension

Epworth Sleepiness Scale may be an indicator for blood pressure profile and prevalence of coronary artery disease and cerebrovascular disease in patients with obstructive sleep apnea

OBJECTIVE

This study seeks to determine whether scores of a short questionnaire assessing subjective daytime sleepiness (Epworth Sleepiness Scale [ESS]) are associated with blood pressure (BP) level, BP profile, and prevalence of related coronary artery disease (CAD) and cerebrovascular disease (CVD) in obstructive sleep apnea (OSA) patients diagnosed by polysomnography (PSG).

METHODS

Twenty university hospital sleep centers in China mainland were organized by the Chinese Medical Association to participate in this study. Between January 2004 and April 2006, 2,297 consecutive patients (aged 18-85 years; 1,981 males and 316 females) referred to these centers were recruited. BP assessments were evaluated at four time points (daytime, evening, nighttime, and morning) under standardized conditions. Anthropometric measurements, medical history of hypertension, CAD, and CVD were collected. ESS score was calculated for each participant and at the night of BP assessment, nocturnal PSG was performed and subjects were classified into four groups based on the apnea-hypopnea index (AHI) from PSG as follows: control group (control, n = 213) with AHI < 5; mild sleep apnea (mild, n = 420) with AHI ≥ 5 and <15; moderate sleep apnea (moderate, n = 460) with AHI ≥ 15 and <30; and severe sleep apnea (severe, n = 1,204) with AHI ≥ 30. SPSS 11.5 software package was used for the relationships between ESS and BP profile and prevalence of CAD and CVD.

RESULTS

ESS is correlated positively with average daytime, nighttime, evening, and morning BP before and even after controlling for confounding effects of age, sex, BMI, AHI, and nadir nocturnal oxygen saturation (before--r = 0.182, 0.326, 0.245, and 0.329, respectively, all P values < 0.001; after--r = 0.069, 0.212, 0.137, and 0.208, respectively, all P values < 0.001). In the severe group, nighttime, evening, morning average BPs (ABPs), the ratio of nighttime/daytime average BP (ratio of nighttime average BP to daytime average BP), and prevalence of hypertension, drug-resistant hypertension (R-HTN), isolated nighttime hypertension (IN-HTN), CAD, and CVD in excessive daytime sleepiness (EDS, ESS ≥ 11) subjects are higher than those in non-EDS (ESS 0-10; t/χ(2) = -8.388, -6.207, -8.607, -5.901, 12.742, 38.980, 16.343, 59.113, and 67.113, respectively; all P values < 0.05). For EDS subjects in the moderate group but not in the control and mild group, nighttime ABP and the ratio of nighttime/daytime average BP are higher (t = -2.086 and -3.815, respectively, all P values < 0.05). Linear fitting with ESS and the ratio of nighttime/daytime average BP shows a positive correlation (r(2) = 0.049, P < 0.001).

CONCLUSIONS

In severe OSA patients with comparable AHI, EDS may identify a subset of individuals with OSA at higher risk of hypertension, R-HTN, IN-HTN, CAD, and CVD. Overall, nighttime ABP seems to be more sensitive to be influenced by EDS than other ABP parameters. Future studies should investigate the potential dose-effect relationship between EDS and hypertension and the possibility that diagnosis and treatment of EDS could aid in BP reduction and ultimately in decreased morbidity and mortality from cardiovascular and cerebrovascular complications (TMUIRB20010002 at www.clinicaltrials.gov ).

The bedtime administration ameliorates blood pressure variability and reduces urinary albumin excretion in amlodipine-olmesartan combination therapy

Chronotherapy has the potential to improve blood pressure (BP) variability and to decrease stroke and cardiovascular events. The present study examined the efficacy and safety of the bedtime administration in amlodipine-olmesartan combination therapy, as compared with the morning administration. The present study was an open-label, randomized crossover study of the effects of the morning vs. bedtime administration of amlodipine-olmesartan combination. The subject was 31 essential hypertensive patients. Morning BP surge (MBPS) and nocturnal BP pattern were analyzed from ambulatory BP data. Glucose and lipid profiles and cardiovascular-renal data were also collected. The bedtime administration reduced MBPS significantly (24.2 ± 13.5 mmHg vs. 32.3 ± 14.2 mmHg, p < 0.001) with no excessive nocturnal BP fall. In nondipper, the bedtime administration significantly improved nocturnal BP. On the other hand, it did not reduce nocturnal BP in dipper. Urinary albumin/creatinine ratio was lower in the bedtime administration than in the morning administration (42.5 ± 59.9 mg/g vs. 75.3 ± 26.4 mg/g, p = 0.044). In amlodipine-olmesartan combination therapy, the bedtime administration reduced better MBPS with correcting nocturnal BP fall and improved urinary albumin excretion. The bedtime dosing of amlodipine and olmesartan seems more apt than the morning dose to obtain the therapeutic goal.

Nondipping phenomenon and quality of life: are they related in essential hypertensive patients?

Hypertensive patients report lower general well-being, more severe psychological distress, poorer perceived health status, more physical symptoms, and functional disability when compared to normotensive patients. Nondipping of blood pressure (BP) is related to increased target organ damage in essential hypertension. However, the specific relationship between nocturnal nondipping and quality of life has not been extensively investigated. Patients with essential hypertension underwent the following procedures: anamnesis, office BP measurement, physical examination, routine biochemistry, and 24-hour ambulatory BP monitoring. To determine renal function, 24-hour urine specimens were collected. Quality of life was assessed by a short form of medical outcomes study (SF-36). Totally, 132 patients (male/female: 55/75) were included. Fifty-five of the patients were nondippers. The dippers and nondippers were not statistically different in terms of socio-demographic parameters. Dippers had higher physical functioning (P- 0.004), bodily pain (P- 0.008), and PCS (P - 0.003) than nondippers. PCS of SF-36 was independently associated with age (P - 0.029), body mass index (P - 0.022), presence of coronary artery disease (P - 0.01), gender (P - 0.009), and dipping phenomenon (P - 0.006). A mental component summary score of SF-36 was not associated with dipping phenomenon. Nocturnal nondipping, apart from having important prognostic implications for cardiovascular complications in essential hypertensive patients, is also related to quality of life, especially in its physical aspects.