Night-day Ratio Research Articles

Associations of dipping and non-dipping hypertension with cardiovascular diseases in patients with dyslipidemia.

IntroductionDyslipidemia combined with hypertension increases the risk of cardiovascular disease (CVD). The current study aimed to investigate the association of dipping and non-dipping hypertension with CVD in patients with dyslipidemia.Material and methodsA total of 243 documented dyslipidemia patients with hypertension were enrolled. Clinical characteristics and clinic and 24-hour blood pressure (BP) parameters were compared between dipping and non-dipping groups based on 24-hour ambulatory blood pressure monitoring. Logistic regression analysis was performed to evaluate the association of dipping and non-dipping hypertension with CVD.ResultsCompared to the dipping group, patients in the non-dipping group were older, more likely to be male and smokers, had higher serum creatinine levels, and were more likely to have chronic kidney disease and CVD (p < 0.05 for all comparisons). No significant between-group differences in clinic systolic and diastolic BP (SBP and DBP) were observed. However, compared to the dipping group, 24-hour SBP, nighttime SBP and DBP, and night-day ratio of SBP and DBP were all significantly higher in the non-dipping group (p < 0.05 for all comparisons). In the dipping group, only night-day ratio of SBP was significantly associated with CVD, with an odds ratio (OR) of 1.09 (95% confidence interval (CI) of 1.02–1.34). In the non-dipping group, both night-day ratio of SBP and DBP were significantly associated with CVD, with an OR of 1.72 (95% CI: 1.33–2.06) and 1.23 (95% CI: 1.05–1.66), respectively.ConclusionsIn patients with dyslipidemia, non-dipping hypertension is more closely related to CVD compared to dipping hypertension.

Preeclampsia is associated with increased ambulatory arterial stiffness index in type 1 diabetes mellitus

IntroductionTreatment of mild to moderate hypertension might not benefit maternal or fetal outcome. This pessimistic point of view may have come about by using non-validated methods for measuring blood pressure in pregnancy combined with inadequate methodology for diagnosis, treatment, and monitoring effects. AimTo determine the association between AASI in women with type 1 diabetes mellitus (T1DM) and preeclampsia, and to assess the ability of AASI to diagnose preeclampsia. Material and methodsRepeated 24-h ambulatory blood pressure recordings were performed three times during pregnancy and once three months postpartum in 151 women with T1DM and 50 control women without diabetes. Circadian rhythm was evaluated as the night day ratio, night blood pressure divided by day blood pressure. ResultsOf the T1DM women, 33 developed preeclampsia, which was associated with AASI in the 3rd trimester (p<0.05). The best predictor of preeclampsia in T1DM was an AASI of 0.35. The diurnal blood pressure was significantly higher in all trimesters in women who later had preeclampsia. A flattened circadian rhythm was present in T1DM women with preeclampsia compared to women without preeclampsia (night-day ratio: systole 2nd trimester: 0.94±0.07 vs. 0.91±0.05, women with and without preeclampsia, respectively, p=0.015; diastole 2nd trimester: 0.89±0.07 vs. 0.85±0.07, p=0.003). AASI was higher during pregnancy compared to postpartum in women with T1DM (0.31±0.16, 0.31±0.16 and 0.33±0.18 vs. 0.25±0.17; 1st, 2nd and 3rd trimester vs. postpartum). ConclusionWomen with T1DM and preeclampsia demonstrate increased arterial stiffness and had early manifestations in the non-dipping of blood pressure.

Nocturnal Hypertension and Altered Night-Day BP Profile and Atherosclerosis in Renal Transplant Patients.

The clinical relevance of ambulatory blood pressure monitoring (ABPM) for risk stratification in renal transplant patients still remains poorly defined. We investigated the association between clinic and ABPM with an established biomarker of atherosclerosis (intima-media thickness [IMT] by echo-color Doppler) in a large, inclusive survey (n = 172) in renal transplant patients at a single institution. Forty-two patients (24%) were classified as hypertensive by ABPM criteria and 29 (17%) by clinic blood pressure (BP) criteria. Average daytime and nighttime BP was 126 ± 12/78 ± 9 mm Hg and 123 ± 13/74 ± 10 mm Hg, respectively. Forty-five patients (26%) were classified as hypertensive by the daytime criterion (>135/85 mm Hg) and a much higher proportion (n = 119, 69%) by the nighttime criterion (>120/70 mm Hg). Sixty-two patients (36%) had a night-day ratio of 1 or greater, indicating clear-cut nondipping. The average nighttime systolic BP (r = 0.24, P = 0.001) and the night-day systolic BP ratio (r = 0.23, P = 0.002) were directly related to IMT, and these associations were much more robust than the 24-hour systolic BP-IMT relationship (r = 0.16, P = 0.04). Average daytime BP and clinic B were unrelated to IMT. In a multiple regression analysis adjusting for confounders, the night-day systolic BP ratio maintained an independent association with IMT (β = 0.14, P = 0.04). In renal transplant patients, the prevalence of nocturnal hypertension by far exceeds the prevalence of hypertension as assessed by clinic, daytime, and 24-hour ABPM. Nighttime systolic BP and the night-day ratio but no other BP metrics are independently associated with IMT. Blood pressure during nighttime may provide unique information for the assessment of cardiovascular risk attributable to BP burden in renal transplant patients.

OP.4D.08] DISORDERED SLEEP BREATHING (SDB) IS THE MAJOR DETERMINANT OF NON-DIPPING AND NOCTURNAL HYPERTENSION IN KIDNEY TRANSPLANT PATIENTS

Objective: In renal transplant patients, the prevalence of nocturnal hypertension by far exceeds that of hypertension as assessed by clinic, daytime, and average 24-hour ABPM and night-time systolic BP (SBP) and the night-day ratio but no other BP metrics are independently associated with IMT in this population (Transplantation 2015 Dec 17). BP during nighttime may provide information for the assessment of CV risk attributable to BP burden in renal transplant patients but the determinants of this phenomenon are still undefined in these patients. Design and method: We recorded 24h-ABPM and performed polysomnography in 215 clinically stable transplant patients. Major classical CV risk factors and CKD-specific risk factors (including phosphate, eGFR, proteinuria and C Reactive Protein) were measured alongside. Our primary goal was to identify the functional correlates of average BP during night-time and of the night/day ratio, a parameter quantifying the BP dipping phenomenon. Results: The Apnea-Hypopnea Index (AHI) exceeded 5 episodes/h in 56 patients and 15 episodes/h in 19. Thus, 17% of patients had mild-to-moderate SDB and 9% severe SDB. In unadjusted analyses, AHI was directly related with night-time SBP (r = 0.19, P = 0.005) and the night/day SBP ratio (r = 0.18, P = 0.01). AHI also associated with average 24h-SBP and DBP (both r = 0.14, P = 0.04). Furthermore, age, gender, BMI, diabetes, phosphate, C-Reactive Protein, and background CV comorbidities were all associated with AHI. In multiple regression analyses adjusting for these parameters as well as for average day-time SBP, Hb, and proteinuria, AHI remained related with average night-time SBP (beta = 0.10, P = 0.02) and with the night/day SBP ratio (beta = 0.17, P = 0.02). In these models, the AHI ranked as the strongest correlate of nigh-time SBP burden. These results did not change also forcing into the model immunosuppressive treatment. Conclusions: In stable transplant patients, sleep disordered breathing is the most powerful functional correlate of nocturnal BP. These relationships are independent of age and comorbidities, eGFR and proteinuria and likely represents irreversible effects of long-term past exposure to kidney failure on the central nervous system.

Abstract 429: Ambulatory Blood Pressure Dipping is Significantly Related to Night/Day Urinary Norepinephrine Ratio

Absence of the normal 10% reduction of ambulatory blood pressure (ABP) from day to night is associated with morbidity and mortality. The cause of this reduction (or its absence) is not completely understood. We studied excretion of norepinephrine (NE) and epinephrine (EPI) on the same day ABP monitoring was performed in 37 healthy volunteers aged 52±7years, with body mass index (BMI) 25±4 Kg/m 2 , and 24-hour ABP 130±11/82±9 mmHg. Overall SBP decreased from day to night 134±13 to 117±10 mmHg, diastolic blood pressure (DBP) from 86±9 to 72±8 mmHg, and heart rate (HR) from 80±10 to 70±9 beats per minute (bpm). Urinary NE and EPI excretion decreased (p&lt;0.005) from 19±10 to 10±6 μmol/mol creatinine, and from 4±2 to 0.8±0.4 μmol/mol creatinine, respectively. Awake or asleep SBP was not correlated to the corresponding NE excretion (r=-0.2, and 0.19). We defined SBP dippers (n=22) as those with a night/day ratio (NDR) of &lt;0.9. There were no differences in age, gender, BMI, 24-hour ABP, daytime DBP, sleep ABP, daytime or sleep HR, or daytime or overnight NE or EPI excretion. On the other hand awake SBP 129±11 mmHg was lower, p&lt;0.05, and NDR DBP 0.89±0.05, NDR HR 0.90±0.05, and NDR NE 0.66±2.7, were significantly higher p&lt;0.05, in the non-dippers (n=15) , than in dippers 138±17mmHg, 0.81±0.05, 0.86±0.8, 0.49±0.18, respectively. In a stepwise multiple regression analysis model with SBP NDR as the dependent variable, awake SBP, p=0.0008, and NDR NE p=0.03, were significant predictors, whereas age and BMI were excluded from the model. In conclusion although day and night blood pressure and urinary NE are not related, the nocturnal decrease of SBP is closely related to the degree of reduction in sympathetic activity as reflected by urinary NE excretion on the same day.

Pulse pressure and systolic night–day ratio interact in prediction of macrovascular disease in patients with type 2 diabetes mellitus

Patients with type 2 diabetes mellitus are at increased risk of cardiovascular disease (CVD). We examined the predictive ability of 24-hour ambulatory pulse pressure (24-h PP), ambulatory arterial stiffness index (AASI) and diurnal blood pressure (BP) parameters for fatal and non-fatal CVD in patients with type 2 diabetes mellitus. A total of 108 patients with type 2 diabetes mellitus (mean duration 6.6 years) were followed for 9.5 (0.5-14.5) years. At baseline, all patients underwent ambulatory BP monitoring. During follow-up, 45 patients had cardiovascular (CV) events (35 non-fatal and 10 fatal). In bivariate analysis, events during follow-up were predicted by 24-h PP (P<0.01), AASI, 24-h systolic BP and systolic and diastolic night-day BP ratio (P<0.05 for all). In Cox regression analysis adjusted for established risk markers, only 24-h PP and systolic night-day BP ratio predicted CV events, P<0.05 for both. A significant interaction between the two parameters was found, P<0.05; thus, the higher the systolic night-day ratio, the greater the increase in hazard ratio (HR) per mmHg increase in 24-h PP and vice versa. A combined 10 mmHg increase in 24-h PP and 10%-point increase in systolic night-day ratio from the 25th percentile increased the adjusted HR (95% confidence interval) for CV events with 1.29 (0.53; 3.12), whereas a similar increase from the 75th percentile increased the HR with 4.2 (1.54; 11,51). Our study showed that 24-h PP and systolic night-day ratio interact as predictors of CV events in type 2 diabetes patients, and should be considered in conjunction when evaluating the risk of CVD.

Increased plasma soluble endoglin levels as an indicator of cardiovascular alterations in hypertensive and diabetic patients

BackgroundEndoglin is involved in the regulation of endothelial function, but there are no studies concerning its relation with hypertension- and diabetes-associated pathologies. Thus, we studied the relationship between plasma levels of soluble endoglin and cardiovascular alterations associated with hypertension and diabetes.MethodsWe analyzed 288 patients: 64 with type 2 diabetes, 159 with hypertension and 65 healthy patients. We assessed the relationship of soluble endoglin plasma levels measured by enzyme-linked immunosorbent assay with basal glycemia, glycosylated hemoglobin, blood pressure, endothelial dysfunction (assessed by pressure wave velocity), hypertensive retinopathy (by Keith-Wagener classification), left ventricular hypertrophy (by Cornell and Sokolow indexes), cardiovascular risk and target organ (heart, vascular, kidney) damage.ResultsThere are significant correlations between endoglin and glycemia, systolic blood pressure, pulse pressure, pressure wave velocity and electrocardiographically assessed left ventricular hypertrophy. Endoglin levels were significantly higher in patients with diabetes who had nondipper and extreme dipper circadian blood pressure patterns than in dipper circadian patterns, in patients with hypertension and diabetes who had riser pattern than in the other patients, and in patients with diabetes but not hypertension who had extreme dipper pattern than in dipper, nondipper and riser groups. There was also a significant correlation between plasma-soluble endoglin and lower levels of systolic night-day ratio. Higher endoglin levels were found in patients with diabetes who had retinopathy, in patients with diabetes who had a high probability of 10-year cardiovascular risk, and in patients with diabetes and hypertension who had three or more damaged target organs (heart, vessels, kidney) than in those with no organs affected.ConclusionsThis study shows that endoglin is an indicator of hypertension- and diabetes-associated vascular pathologies as endothelial dysfunction and cardiovascular damage.

A Prospective Observational Study of Changes in Renal Function and Cardiovascular Risk Following Living Kidney Donation

The effect of unilateral nephrectomy on the cardiovascular risk profile of living kidney donors has not been prospectively studied. We performed an observational cohort study of 58 living donors to 6 months postdonation for changes in 24-hr ambulatory blood pressure profiles, renal function, urine protein excretion, body mass index, glucose tolerance, and fasting lipid profiles. The 24-hr systolic blood pressure average and night-day ratio were unchanged from pre- to postdonation (118.9+/-11 vs. 118.1+/-14 mm Hg, P=0.77; 0.87+/-0.07 vs. 0.87+/-0.09, P=0.68, respectively). Estimated glomerular filtration rate declined from 91.9+/-16 to 61.6+/-12 mL/min/1.73 m2 (P<0.0001). Protein excretion, body mass index, glucose, and lipids were unchanged. No significant differences were noted between dippers and nondippers either pre- or postdonation. In summary, living kidney donation in the short term is safe. We suggest further observation of individuals with lower glomerular filtration rate for possible increased cardiovascular risk factors in the future.

Changing the Timing of Antihypertensive Therapy to Reduce Nocturnal Blood Pressure in CKD: An 8-Week Uncontrolled Trial

Nondipping status is associated with greater cardiovascular morbidity and mortality and faster progression of chronic kidney disease (CKD). We examined whether shifting 1 antihypertensive drug from morning to evening restores the circadian rhythm of blood pressure in nondipper patients with CKD. 8-week clinical trial without a control group. We selected from our outpatient renal clinic 32 patients with CKD with estimated glomerular filtration rate less than 90 mL/min/1.73 m(2) and night-day ratio of mean ambulatory blood pressure (ABP) greater than 0.9, but with normal daytime ABP (<135/85 mm Hg) to avoid the required therapy intensification. Shifting 1 antihypertensive drug from morning to evening. Percentage of patients changing the night-day ratio of mean ABP from greater than 0.9 to 0.9 or less 8 weeks after the shift. Office blood pressure/ABP and proteinuria at baseline and after the shift. There were 55% men with a mean age of 67.4 +/- 11.3 years and estimated glomerular filtration rate of 46 +/- 12 mL/min/1.73 m(2). They were treated with 2.4 +/- 1.4 antihypertensive drugs. After the drug shift, the night-day ratio of mean ABP decreased in 93.7% of patients, with normal circadian rhythm restored in 87.5%. The nocturnal systolic and diastolic ABP decrease was not associated with an increase in diurnal ABP and was independent from number and class of shifted drug. Office blood pressure in the morning also decreased (from 136 +/- 16/77 +/- 10 to 131 +/- 13/75 +/- 8 mm Hg; P = 0.02). Urinary protein excretion decreased from 235 +/- 259 to 167 +/- 206 mg/d (P < 0.001). Absence of a control group and patients with severe proteinuria or uncontrolled daytime ABP. In nondipper patients with CKD, changing the timing of antihypertensive therapy decreases nocturnal blood pressure and proteinuria.

Research Article: Temperature and photoperiod effects on activity of the northern short-tailed shrew (Blarina brevicauda)

Changes in pattern of activity may help shrews survive harsh winter conditions. In particular, shrews may become less active and less nocturnal during winter. To better understand the mechanisms underlying the shrew response to winter conditions we measured several kinds of activity and an index of nocturnality (night-day ratio) for six northern short-tailed shrews (Blarina brevicauda) in laboratory activity chambers. Experimental conditions were light:dark (L:D) cycles of 16:8 or 8:16 crossed with temperatures of 5°C or 19°C. Shrews were given unlimited food and prevented from hoarding. Feeding activity was greater (P < 0.001) and time spent out of the den was less concentrated during night (P = 0.021) at 5°C than 19°C. Overall activity did not vary with photoperiod or temperature, but shrews were more consistently active through the day at lower temperatures. Shrews may become less strictly nocturnal during winter because of the need to forage more frequently during the day. Food limitation and hoarding, which were not considered in this study, may be important factors affecting the reduced levels of activity during winter observed in other studies of shrews.

Nocturnal hypoxemia, night-day arterial pressure changes and left ventricular geometry in dialysis patients

Nocturnal hypoxemia, night-day arterial pressure changes and left ventricular geometry in dialysis patients

Diurnal blood pressure patterns in normotensive and hypertensive children and adolescents.

As abnormalities in diurnal ambulatory blood pressure (BP) have been associated with hypertensive target organ damage in adults, we investigated the diurnal systolic BP (SBP) and diastolic BP (DBP) patterns of 54 normotensive children, age 13.4 +/- 3.0 years, and 45 untreated borderline and mildly hypertensive children, age 14.4 +/- 2.6 years. Subjects wore the SpaceLabs 90207 ambulatory BP monitor for 24 h. BP was measured q 15 min from 08.00-21.00 h then q 30 min from 21.00-08.00 h. Nocturnal BP fall, the night-day ratio and cusum derived measures were calculated from time-weighted daytime and night-time SBP and DBP. The groups were compared using analysis of covariance with adjustment for age, race, gender and body mass index. The influence of age, gender and race on the diurnal BP profile was also examined. Nocturnal SBP fall was greater in hypertensive compared to normotensive subjects (17.1 +/- 6.7 vs 14.6 +/- 7.1 mm Hg; unadjusted mean +/- s.d., P = 0.022). Normotensive and hypertensive groups did not differ in nocturnal DBP fall or SBP or DBP night-day ratio. Race appeared to influence the diurnal BP pattern as black subjects had less nocturnal SBP fall (12.9 +/- 6.9 vs 17.1 +/- 6.5 mm Hg; P < 0.005) and a higher night-day SBP ratio (90.1 +/- 5.3 vs 86.7 +/- 4.6%; P < 0.005) than white subjects. In conclusion, hypertensive children and adolescents have a similar diurnal BP pattern as their normotensive counterparts, except that the entire BP profile is shifted upward with a greater absolute fall in SBP at night. Race also appears to influence the diurnal BP profile of normotensive and hypertensive children and adolescents.

Nocturnal blood pressure fall on ambulatory monitoring in a large international database. The "Ad Hoc' Working Group.

A wide range of definitions is used to distinguish subjects in whom blood pressure (BP) falls at night (dippers) from their counterparts (nondippers). In an attempt to standardize the definition of nondipping, we determined the nocturnal BP fall and night-day BP ratio by 24-hour ambulatory monitoring in 4765 normotensive and 2555 hypertensive subjects from 10 to 99 years old. In all subjects combined, the systolic/diastolic nocturnal fall and corresponding ratio averaged (+/- SD) -16.7 +/- 11.0/ -13.6 +/- 8.1 mm Hg and 87.2 +/- 8.0%/83.1 +/- 9.6%, respectively. In normotensive subjects, the 95th percentiles were -0.3/-1.1 mm Hg for the nocturnal fall and 99.7%/98.3% for the night-day ratio. Both the fall and ratio showed a curvilinear correlation with age. The smallest fall and largest ratio were observed in older (> or = 70 years) subjects. A higher BP on conventional sphygmomanometry was associated with a larger systolic (partial r = .11) and diastolic (r = .12) nocturnal BP fall. The diastolic (r = .08) but not the systolic night-day ratio increased with higher conventional BP. The nocturnal BP fall was larger and the corresponding night-day ratio smaller in oscillometric (n = 5884) than in auscultatory (n = 1436) recordings, in males (n = 3730) than in females (n = 3590), and in Europe (n = 4556) than in the other continents (n = 2764). The distributions of the nocturnal BP fall and night-day ratio showed considerable overlap among normotensive and hypertensive subjects, but the overlap tended to be larger for the ratio than for the fall. Of all subjects, 3.2% had systolic and diastolic ratios of 100% or more. With adjustments applied for confounders, the probability of being a nondipper increased 2.8 times (95% confidence interval, 2.0-4.0) from 30 to 60 years and 5.7 times (4.4-7.4) from 60 to 80 years. The odds ratios were 1.0 (0.8-1.4) for males versus females. 1.6 (1.2-2.1) for subjects with definite hypertension versus normotensive subjects, 2.4 (1.2-4.7) for Asians (n = 2213, 96% Japanese) versus inhabitants of the other continents, and 2.4 (1.5-3.8) for subjects examined with auscultatory versus oscillometric devices. In conclusion, the mathematical definition of nondipping, ie, having a night-day ratio of 100% or more for systolic and diastolic BPs, closely approximated the 95th percentiles of the night-day ratio in normotensive subjects. The ratio depends less on BP level than the nocturnal BP fall and is therefore to be preferred in the definition of dipping status. Notwithstanding the present findings, the reproducibility of nondipping and its prognostic significance need further clarification.