Impact of postures on blood pressure in healthy subjects

Association of Postural Blood Pressure Response With Disease Severity in Primary Open Angle Glaucoma

PRCIS

Patients with primary open angle glaucoma (POAG) demonstrated exaggerated postural blood pressure dip in recumbency that was positively correlated with the severity of glaucomatous optic neuropathy (GON). Postural dip testing can be used clinically as a marker of systemic vascular dysregulation in GON risk assessment.

OBJECTIVE

To investigate whether patients with POAG demonstrated abnormal postural blood pressure response to recumbency and whether such abnormal postural response correlated with GON severity.

PATIENTS AND METHODS

This is a prospective observational study where 47 patients with POAG underwent intraocular pressure and systemic arterial blood pressure, systolic blood pressure (SBP) and diastolic blood pressure (DBP), measurement in seated and after 20-minute recumbency positions. Mean arterial blood pressure (MABP) was calculated for seated and recumbent positions. The percentage difference between seated and recumbent SBP, DBP, and MABP was calculated according to which participants were divided into 3 groups, that is, nondippers, normal dippers, and exaggerated dippers with percentage dips of <10%, ≥10%≤20%, >20%, respectively. Participants underwent optical coherence tomography of optic nerve head to measure retinal nerve fiber layer thickness (RNFLT) which was used as a structural biomarker of GON.

RESULTS

RNFLT was lower in exaggerated dippers than in nondippers and normal dippers. There was a negative correlation between postural dip and average RNFLT. Linear regression showed that postural dip was associated with lower RNFLT independent of age and intraocular pressure. The χ 2 independence test demonstrated a strong relation among corresponding dip groups for SBP, DBP, and MABP. However, it showed no significant relation between hypertension and postural dip. Fisher exact test showed no relation between antihypertensive medication and postural dip.

CONCLUSIONS

Patients with POAG demonstrated abnormal postural blood pressure response comprising exaggerated recumbent dip which was positively correlated with disease severity. Postural dip assessment may serve as a simple clinic-based test of systemic vascular dysregulation as part of GON risk evaluation.

Simultaneous influence of sex and age on blood pressure difference between supine and sitting body positions

OBJECTIVES

Doctors' offices and outpatient departments typically measure blood pressure (BP) with the patient in a sitting position, whereas inpatient departments also use the supine position. As sex and age influence the autonomic function associated with BP regulation our study compared BP measurements in supine and sitting positions for men and women of different ages.

METHODS

We included 91 men and 118 women (≥18 years) without severe diseases. Hypertension was not an exclusion criterion because it is common in older persons. Mean left brachial BP and heart rate were determined by a digital sphygmomanometer in supine position as well as in sitting position before and after hand force measurement.

RESULTS

In a supine position women had slightly lower diastolic BP values than men. After sitting up, the diastolic BP increased in nearly all subjects. This increase was greater in women older than 50 years than for aged-matched men. In contrast to diastolic BP the systolic BP increased after sitting up in only two thirds of the subjects. Especially in women younger than 50 years the systolic BP often did not increase but decreased in response to postural change. The pulse pressure was mostly reduced after sitting up. This reduction was more pronounced in women than men independent of age and physical effort (i.e. hand force measurement). The sitting position also caused an increased heart rate, which was independent of sex and age.

CONCLUSION

Postural changes in the systolic and diastolic BP simultaneously depend on sex and age that needs to be considered for BP measurements in supine and sitting body positions.

The association between PTSD and cardiovascular disease and its risk factors in male veterans of the Iraq/Afghanistan conflicts: a systematic review

Military personnel with Post-Traumatic Stress Disorder (PTSD) can experience high levels of mental and physical health comorbidity, potentially indicating a high level of functional impairment that can impact on both military readiness and later ill-health. There is strong evidence to implicate PTSD as a contributory factor to Cardiovascular Disease (CVD) among serving personnel and veterans. This systematic review focusses on the association between PTSD and cardiovascular disease/risk factors in male, military serving and ex-serving personnel who served in the Iraq/Afghanistan conflicts. PUBMED, MEDLINE, PILOTS, EMBASE, PSYCINFO, and PSYCARTICLES were searched using PRISMA guidelines. Three hundred and forty-three records were identified, of which 20 articles were selected. PTSD was positively associated with the development of CVD, specifically circulatory diseases, including hypertension. PTSD was also positively associated with the following risk factors: elevated heart rate, tobacco use, dyslipidaemia, and obesity. Conflicting data is presented regarding heart rate variability and inflammatory markers. Future studies would benefit from a standardized methodological approach to investigating PTSD and physical health manifestations. It is suggested that clinicians offer health advice for CVD at an earlier age for ex-/serving personnel with PTSD.

Epidemiological and clinical implications of blood pressure measured in seated versus supine position

The evidence concerning how posture influences blood pressure is not consistent. The aim of this cross-sectional study was to consider the clinical and epidemiological implications of blood pressure measured in seated versus supine position, and to investigate the impact of age, sex, body mass index (BMI), and diabetes on these differences.This study included 1298 individuals (mean age 58.6 ± 11.8 years) from the Vara-Skövde cohort at the 10 years' follow-up visit in 2014. Physical examination included blood pressure measurements in seated and supine position. Self-reported information on diabetes status, hypertension, ongoing medication, leisure time physical activity, and smoking habits were obtained. Linear regression models accounted for differences in age, sex, BMI, and known diabetes.Both systolic and diastolic blood pressure were significantly higher in the seated position [1.2 mm Hg, P < .001, 95% confidence interval (95% CI) 0.79-1.54 and 4.2 mm Hg, P < .001, 95% CI 4.08-4.71, respectively]. The prevalence of high blood pressure in seated position was higher (19.9%) than in supine position (13.5%). Linear regression analysis showed that age (β = -0.215, P < .001) and diabetes (β = -0.072, P = .012) were associated with smaller differences in postural diastolic blood pressure and BMI (β = 0.124, P < .001) with greater difference.This study showed substantial postural differences in blood pressures measured in office. Measuring blood pressure in the supine position shows lower blood pressure readings when compared with the seated position. Clinicians should be aware of how age, BMI, and diabetes influence these differences.

Factors affecting the determination of cerebrovascular reactivity

BACKGROUND AND PURPOSE

Cerebrovascular reactivity (CVR), measures the ability of the cerebrovasculature to respond to vasoactive stimuli such as CO2. CVR is often expressed as the ratio of cerebral blood flow change to CO2 change. We examine several factors affecting this measurement: blood pressure, stimulus pattern, response analysis and subject position.

METHODS

Step and ramp increases in CO2 were implemented in nine subjects, seated and supine. Middle cerebral artery blood flow velocity (MCAv), and mean arterial pressure (MAP) were determined breath-by-breath. Cerebrovascular conductance (MCAc) was estimated as MCAv/MAP. CVR was calculated from both the relative and absolute measures of MCAc and MCAv responses.

RESULTS

MAP increased with CO2 in some subjects so that relative CVR calculated from conductance responses were less than those calculated from CVR calculated from velocity responses. CVR measured from step responses were affected by the response dynamics, and were less than those calculated from CVR measured from ramp responses. Subject position did not affect CVR.

CONCLUSIONS

(1) MAP increases with CO2 and acts as a confounding factor for CVR measurement; (2) CVR depends on the stimulus pattern used; (3) CVR did not differ from the sitting versus supine in these experiments; (4) CVR calculated from absolute changes of MCAv was less than that calculated from relative changes.

Systolic blood pressure reactivity during submaximal exercise and acute psychological stress in youth

BACKGROUND

Studies in youth show an association between systolic blood pressure (SBP) reactivity to acute psychological stress and carotid artery intima-media thickness (CIMT). Submaximal exercise produces similar cardiovascular responses as acute psychological stress and may be a valuable tool to assess SBP reactivity in youth. However, it has not yet been determined whether SBP reactivity during submaximal exercise in youth is associated with CIMT, as it is during psychological stress.

METHODS

Fifty-four adolescents aged 13-16 years completed 3 visits. On one visit, adolescents completed three, 4-minute stages of increasing intensity on a treadmill. On another visit, adolescents completed measures of acute psychological stress reactivity (star tracing, speech preparation, speech). On a third visit, adolescents completed an ultrasound scan to measure CIMT.

RESULTS

SBP reactivity during lower- (β = 0.29, P = 0.03) and higher-intensity (β = 0.31, P = 0.02) submaximal exercise was associated with greater CIMT. SBP reactivity during higher-intensity submaximal exercise was positively associated with SBP reactivity during star tracing (β = 0.34, P = 0.01), speech preparation (β = 0.37, P = 0.007), and speech (β = 0.41, P = 0.003).

CONCLUSIONS

Greater SBP reactivity during submaximal exercise in healthy adolescents was associated with greater CIMT, similar to SBP reactivity during acute psychological stress. Adolescents who had greater SBP reactivity during exercise also demonstrated greater SBP reactivity during the psychological stress tasks. Given that exercise testing can be standardized for comparison across studies, submaximal exercise tests may be a valuable tool to assess SBP reactivity in youth.