Postural changes in blood pressure and pulse rate among black adolescents and white adolescents: the Minneapolis Children's Blood Pressure Study

Changes in Retinal Optical Coherence Tomography Angiography Indexes Over 24 Hours

Purpose

To evaluate changes in the retinal microvasculature of young adults over 24 hours using optical coherence tomography angiography (OCT-A).

Methods

Participants (n = 44, mean age 23.2 ± 4.1 years, 24 myopes and 20 nonmyopes) with normal ophthalmological findings were recruited. Two macular OCT-A and OCT scans, systemic blood pressure, intraocular pressure (IOP), and biometry measurements were taken every four hours over 24 hours. Superficial and deep retinal layer en face images were analyzed to extract magnification-corrected vascular indexes using image analysis including foveal avascular zone metrics, vessel density, and perfusion density for the foveal, parafoveal, and perifoveal zones.

Results

Significant diurnal variations (P < 0.001) were observed in the vessel and perfusion density in the three superficial retinal layer regions, with acrophase between 4:30 PM and 8:30 PM. Only foveal and parafoveal regions of the deep retinal layer exhibited significant diurnal variations with acrophase between 9 AM and 3 PM. Myopes and nonmyopes had different acrophases but not amplitudes in the parafoveal perfusion density of superficial retinal layer (P = 0.039). Significant correlations were observed between diurnal amplitudes or acrophases of superficial retinal layer indexes and systemic pulse pressure, IOP, axial length and retinal thickness.

Conclusions

This study shows, for the first time, that significant diurnal variation exists in OCT-A indexes of macular superficial and deep retinal layer over 24 hours and were related to variations in various ocular and systemic measurements. Myopes and nonmyopes showed differences in the timing but not in amplitude of the superficial retinal layer parafoveal perfusion density variations but not in deep retinal layer.

Monitoring nutritional status accurately and reliably in adolescents with anorexia nervosa

AIM

Accurate assessment of nutritional status is a vital aspect of caring for individuals with anorexia nervosa (AN) and body mass index (BMI) is considered an appropriate and easy to use tool. Because of the intense fear of weight gain, some individuals may attempt to mislead the physician. Mid-upper arm circumference (MUAC) is a simple, objective method of assessing nutritional status. The setting is an eating disorders clinic in a tertiary paediatric hospital in Western Australia. The aim of this study is to evaluate how well MUAC correlates with BMI in adolescents with AN.

METHODS

Prospective observational study to evaluate nutritional status in adolescents with AN.

RESULTS

Fifty-five adolescents aged 12-17 years with AN were assessed between January 1, 2004 and January 1, 2006. MUAC was highly correlated with BMI (r = 0.79, P < 0.001) and individuals with MUAC >or=20 cm rarely required hospitalisation (negative predictive value 93%).

CONCLUSIONS

MUAC reflects nutritional status as defined by BMI in adolescents with AN. Lack of consistency between longitudinal measurements of BMI and MUAC should be viewed suspiciously and prompt a more detailed nutritional assessment.

Trajectory of systolic blood pressure in children and adolescents

PURPOSE

Rapid height and weight changes during childhood contribute markedly to blood-pressure change during children's physical growth. This article evaluates the differences in systolic blood pressure (SBP) growth or changes between four gender-ethnic groups: African American males (AM), Caucasian males (CM), African American females (AF), and Caucasian females (CF).

METHODS

Subjects 6-9 years old at entry (n = 1302) were followed for 12 years. The repeated-measure data of SBP were analyzed using the Gompertz growth model with random coefficients.

RESULTS

Mean SBP (mmHg) at age 6 years was lowest in African American girls (82.23 +/- 0.76) and highest in Caucasian boys (102.83 +/- 0.5). And for both ethnic groups, girls had lower levels at which SBP growth stopped. The peak growth ages (years) also differed by group: 9.30 +/- 0.73, 9.91 +/- 0.28, 10.00 +/- 0.82, and 10.60 +/- 0.22 for African American girls, African American boys, Caucasian girls and Caucasian boys, respectively.

CONCLUSION

SBP growth differed among gender-ethnic groups with respect to mean SBP level at age 6, the level at which SBP growth stops and the mean age at which SBP growth rate was at its peak.

Descriptive epidemiology of blood pressure response to change in body position. The ARIC study

The epidemiology of a common measure of cardiovascular reactivity, the change in systolic blood pressure (DeltaSBP) from the supine to the standing position, is described in a cohort of 13 340 men and women aged 45 to 65 years enrolled in the Atherosclerosis Risk in Communities (ARIC) Study. The distribution of DeltaSBP was found to be symmetrical and unimodal, with a mean value near zero (-0.45 mm Hg). The range of DeltaSBP was from -63.2 to 54.3 mm Hg, and the standard deviation was 10.8. Stratification of DeltaSBP by race and gender shows a slight shift in distribution toward higher values for black men and women. DeltaSBP was categorized into deciles. Participants in the top 30% and bottom 30% of the distribution were compared with individuals in the middle 40% of the distribution, who had little or no change in SBP on standing. Participants in the bottom 30% (ie, SBP decreased on standing) were significantly older, had a greater prevalence of hypertension and peripheral vascular disease, had higher values of SBP, and had more cigarette-years of smoking. Among participants in the top 30% (ie, SBP increased on standing), a significantly larger proportion were black, mean seated SBP was higher, and the predicted risk of developing coronary heart disease after 8 years was greater. The response of SBP to change in posture showed considerable variability in a population sample of middle-aged adults. Cardiovascular morbidity, sociodemographic factors, and cigarette smoking were associated with the magnitude and direction of the postural change.

Postural effects on hemodynamic response to interpersonal interaction

Laboratory studies of stress-induced cardiovascular reactivity have been conducted predominantly with participants in a seated posture. This procedure may contribute to limited laboratory-field generalization of cardiovascular response. The present study examined hemodynamic adjustments underlying pressor responses, in addition to heart rate and systolic time intervals, during seated and standing role-played, interpersonal interaction in 60 young adults. Irrespective of gender or race, blood pressure responses to the seated and standing interactions were comparable. However, seated interactions yielded a significantly greater increase in heart rate, shortened preejection period and decreased stroke index as compared to standing. Alternatively, interacting while standing yielded a significantly increased left ventricular ejection time and total peripheral resistance in comparison to sitting. These results suggest that hemodynamic adjustments during stressful interpersonal interaction vary as a function of posture, with somewhat greater cardiac influences apparent while seated and a more pronounced vascular response while standing.

The cardiovascular response to postural change as a function of race

Little is known about racial differences in cardiovascular responses to postural change. The immediate and delayed change from sitting to standing was studied in 207 healthy young Asian, black, and white men and women by means of a noninvasive blood pressure tracking system. Whereas Asians and whites had decreased mean arterial pressure (MAP) 32-41 s after standing, blacks had an increase. During the delayed response (3 min after standing), compared to Asians and whites, blacks had greater increases in diastolic blood pressure and MAP. Their heart rate increase was also greater than Asians. For systolic blood pressure and pulse pressure there were Race x Family History interactions for the immediate response to orthostasis and Race x Gender interactions for the delayed response. Blacks generally displayed different cardiovascular patterns from the other two racial groups, possibly reflecting increased peripheral resistance and altered baroreceptor function.

Consistency of ethnic differences in children's pressor reactivity. 1987 to 1992

In this prospective investigation, all children enrolled in the public third-grade classrooms of an entire county (n = 474) had blood pressure measured both at rest and during a stressful television video game. Examinations were repeated in 4 subsequent years when cohort children as well as newly enrolled children were in grades 4, 5, 7, and 8. Both cross-sectional and longitudinal analyses indicated that black children demonstrated significantly greater systolic and diastolic pressor reactivity than white children. These data suggest that ethnic differences in children's pressor reactivity presage ethnic differences in adulthood hypertension.

Postural stability of hemodynamic responses during mental challenge

Laboratory stress testing is typically conducted while subjects are seated, whereas real-life stressors may often be encountered while standing. The present study of 20 healthy young men evaluated blood pressure and underlying hemodynamic adjustments to a standardized mental arithmetic task performed twice while seated and twice while standing. Blood pressure increased during mental arithmetic in both postures, but the underlying hemodynamic determinants of the pressor responses were different for the two postures. Augmented cardiac output was responsible for increasing blood pressure during seated task performance, whereas increased vascular resistance was the mechanism for the pressor response to the task performed while standing. Blood pressure and hemodynamic responses were reproducible subject characteristics for a given posture; test-retest correlations were significant for all cardiovascular measures. However, seated blood pressures responses were not significantly correlated with standing blood pressure responses. In contrast, significant between-posture correlations were found for cardiac output and vascular resistance responses. This preliminary evidence of postural stability of the hemodynamic determinants of blood pressure responses during stress is consistent with growing evidence that hemodynamic response tendencies are robust characteristics of reactivity. Ambulatory monitoring of hemodynamic response patterns during real-life stress may reveal more idiosyncratic profiles of stress reactivity than are displayed by blood pressure responses alone.

Orthostatic hypotension in older adults. The Cardiovascular Health Study. CHS Collaborative Research Group

The purpose of the present study was to assess the prevalence of orthostatic hypotension and its associations with demographic characteristics, cardiovascular risk factors and symptomatology, prevalent cardiovascular disease, and selected clinical measurements in the Cardiovascular Health Study, a multicenter, observational, longitudinal study enrolling 5,201 men and women aged 65 years and older at initial examination. Blood pressure measurements were obtained with the subjects in a supine position and after they had been standing for 3 minutes. The prevalence of asymptomatic orthostatic hypotension, defined as 20 mm Hg or greater decrease in systolic or 10 mm Hg or greater decrease in diastolic blood pressure, was 16.2%. This prevalence increased to 18.2% when the definition also included those in whom the procedure was aborted due to dizziness upon standing. The prevalence was higher at successive ages. Orthostatic hypotension was associated significantly with difficulty walking (odds ratio, 1.23; 95% confidence interval, 1.02, 1.46), frequent falls (odds ratio, 1.52; confidence interval, 1.04, 2.22), and histories of myocardial infarction (odds ratio, 1.24; confidence interval, 1.02, 1.50) and transient ischemic attacks (odds ratio, 1.68; confidence interval, 1.12, 2.51). History of stroke, angina pectoris, and diabetes mellitus were not associated significantly with orthostatic hypotension. In addition, orthostatic hypotension was associated with isolated systolic hypertension (odds ratio, 1.35; confidence interval, 1.09, 1.68), major electrocardiographic abnormalities (odds ratio, 1.21; confidence interval, 1.03, 1.42), and the presence of carotid artery stenosis based on ultrasonography (odds ratio, 1.67; confidence interval, 1.23, 2.26). Orthostatic hypotension was negatively associated with weight. We conclude that orthostatic hypotension is common in the elderly and increases with advancing age. It is associated with cardiovascular disease, particularly those manifestations measured objectively, such as carotid stenosis. It is associated also with general neurological symptoms, but this link may not be causal. Differences in prevalence of and associations with orthostatic hypotension in the present study compared with others are largely attributed to differences in population characteristics and methodology.

Correlates of postural hypotension in a community sample of elderly blacks and whites

Postural hypotension is thought to be prevalent among the elderly, but few community-based studies of this condition have been conducted. In addition, little is known about postural hypotension in blacks despite well documented racial differences in hypertension and stroke. Data on 659 elderly (greater than or equal to 60 years of age) participants in a survey of two rural, biracial townships were analyzed to describe the frequency and correlates of postural hypotension. Twelve percent of the 659 adults experienced a drop of 10 mmHg or greater in systolic blood pressure on going from sitting to standing (supine measures were not available). This degree of postural hypotension was twice as common for whites as for blacks (14.5% vs 7.5%, P = 0.01). Postural hypotension was associated with elevated sitting blood pressure and showed positive but statistically non-significant relationships with anti-hypertensive medications and leanness. The association between race and postural hypotension persisted after adjusting for these and other risk factors (OR = 2.2, 95% CI:1.2,4.0).

Postural effects on blood pressure reactivity: implications for studies of laboratory-field generalization

This study was designed as an in-laboratory evaluation of the significance of postural blood pressure (BP) adjustments in the investigation of laboratory-field generalization. Blood pressure responses were monitored while 20 subjects completed a mental arithmetic task in two postures, seated and standing. Baseline data were also collected in each posture. The standing challenge was regarded as a laboratory representation of real-world standing challenges. Reactivity scores for the seated stressor were calculated as seated task level minus seated baseline level. For the standing stressor, they were calculated in two ways; standing task level minus standing baseline, and standing task level minus seated baseline. It was hypothesized that the standing reactivity scores calculated from standing baselines (i.e. from the same-posture baselines) would be more highly correlated with seated reactivity than would the standing reactivity scores calculated using sitting baselines. This was not found to be the case for either SBP or DBP. Absolute task SBP levels were very similar in both postures, while they were significantly different for DBP, with standing task levels being higher. It was concluded that ignoring posture will not mask SBP reactivity associations between laboratory and field, but that it may do so for DBP, particularly in future studies as our overall understanding of laboratory-field generalization increases.