Effects of supine blood pressure on interpretation of standing up test in 500 patients with diabetes mellitus

Determinants of orthostatic hypotension in type 2 diabetes: is cardiac autonomic neuropathy the main factor?

OBJECTIVES

To evaluate the determinants of orthostatic hypotension (OH) in type 2 diabetes (T2D) and the usefulness of ΔHR/ΔSBP, index of cardiac baroreflex function, in identifying neurogenic OH.

METHODS

In 208 participants with T2D, we performed three heart rate based cardiovascular reflex tests (HR-CARTs) and OH test and assessed clinical history and variables. We defined OH as a systolic blood pressure (BP) fall ≥20 and ≥30 mmHg with supine BP <140 and ≥140 mmHg, respectively, and early and confirmed CAN based on 1 and 2 abnormal HR-CARTs. In participants with OH, we measured ΔHR/ΔSBP, using data from the lying to standing and OH test, and its diagnostic accuracy for neurogenic OH (as OH plus confirmed HR-CAN).

RESULTS

OH was present in 25 participants and associated with lower HR-CARTs (P=0.01), higher HbA1c (P=0.0048), presence of CAN (P=0.0058), retinopathy (P=0.037), and peripheral vascular disease (P=0.0056), absence of hypertension (P=0.0008) and physical activity (P=0.0214), but not with interfering drugs and beta-blockers. In a multiple logistic regression, HR-CAN was the main independent determinant of OH (odds ratio: 4.74) with physical activity and hypertension (odds ratio: 0.16 and 0.23) (R2=0.22). ΔHR/ΔSBP had a good diagnostic accuracy for neurogenic OH (AUC: 0.816±0.087), and at the cut-off of 0.5 bpm/mmHg a sensitivity of 100% and specificity of 63.2%.

CONCLUSION

CAN is still the main determinant of OH in T2D but does not explain all its variance with contribution of comorbidities and physical inactivity. The index ΔHR/ΔSBP might represent a useful clinical tool to identify neurogenic OH.

Supine Hypertension Is Associated With an Impaired Cerebral Oxygenation Response to Orthostasis: Finding From The Irish Longitudinal Study on Ageing

[Figure: see text].

Differences in blood pressure by body position (supine, Fowler's, and sitting) in hypertensive subjects

BACKGROUND

Although blood pressure (BP) differences from supine to sitting position have long been recognized, limited data are available on other commonly used body positions. We performed a cross-sectional study to compare BP values obtained in supine, sitting, and Fowler's positions in essential hypertensive subjects.

METHODS

Systolic BP (SBP) and diastolic BP (DBP) were recorded using an automatic oscillometric device. Nine measurements were taken: three measurements, in random order, in supine, Fowler's, and sitting position. Two generalized estimating equations models were used to evaluate potential predictors of SBP and DBP adjusting for heart rate and measurement order.

RESULTS

The sample consisted of 250 subjects (mean age 66.3 ± 13.4 years; 44.4% males). Measured in supine, Fowler's, and sitting position, mean SBPs were 139.3 ± 14.0; 138.1 ± 13.8; 137.2 ± 13.7 mm Hg, respectively, and mean DBPs 80.1 ± 9.1; 81.9 ± 9.4; 83.0 ± 9.6 mm Hg, respectively. At multivariate analysis, mean SBP significantly decreased if measured in Fowler's and sitting positions, as compared to supine. In contrast, DBP significantly increased. A relevant proportion of subjects showed large differences (≤ or ≥10 mm Hg) in mean SBP across positions: i.e., 30.0% comparing supine vs. sitting SBP. An even higher prevalence of large differences was observed according to the measurement order within the same positions, with no univocal direction (random variation).

CONCLUSIONS

Fowler's position may represent a valid alternative to sitting and supine positions for BP measurement in clinical practice. BP random variability was found to be large regardless of body position, reinforcing the need for operators to closely follow current guidelines that recommend ≥2 recordings at each measurement.

Reappraisal of the diagnostic role of orthostatic hypotension in diabetes

OBJECTIVE

Given the controversial aspects of orthostatic hypotension (OH) testing in diabetes, we evaluated the diagnostic role for cardiac autonomic neuropathy (CAN) and for nondipping of OH, defined according to a fall in systolic blood pressure (BP) > or = 30 (30-OH) or > or = 20 mmHg (20-OH).

METHODS

164 diabetic patients underwent 24 hours BP monitoring, three heart rate cardiovascular tests, and OH test.

RESULTS

Compared to 30 mmHg, the 20 mmHg criterion increased the frequency of OH from 11 to 19.5%. Both 30-OH and 20-OH were associated with CAN (chi (2) = 30.5, P < 0.0001, and chi (2) = 45.1, P < 0.0001, respectively) and nondipping (chi (2) = 31.7, P < 0.0001, and chi (2) = 17.2, P = 0.0001, respectively). ROC curve for orthostatic systolic BP fall provided an AUC of 0.79 +/- 0.04 (95% CI 0.70-0.86) for diagnosing CAN and of 0.77 +/- 0.05 (95% CI 0.66-0.86) for diagnosing nondipping. Both 30-OH and 20-OH showed a low sensitivity and high specificity for CAN [sensitivity 31%, specificity 98%, Likelihood Ratio for a positive result (LR(+)) 17.1; and sensitivity 50%, specificity 95%, LR(+) 9.3, respectively], and for nondipping (sensitivity 40%, specificity 96%, LR(+) 8.9, and sensitivity 47%, specificity 87%, LR(+) 3.5, respectively), having 30-OH a higher LR(+) in both cases.

INTERPRETATION

OH had only moderate diagnostic accuracy, with high specificity and low sensitivity, for CAN, diagnosed on the basis of heart rate cardiovascular tests, and-as a novel finding-also for nondipping. A different definition of OH did not substantially affect its diagnostic characteristics, with just a slightly greater ability of the 30 mmHg criterion to estimate the probability of CAN and nondipping.

Population-based study on the prevalence and risk factors of orthostatic hypotension in subjects with pre-diabetes and diabetes

OBJECTIVE

The aim of this study was to investigate the relationship between pre-diabetes and orthostatic hypotension and to examine the prevalence and correlates of orthostatic hypotension in community dwellers with normal glucose tolerance (NGT), pre-diabetes, and diabetes.

RESEARCH DESIGN AND METHODS

All participants were classified as having NGT (n = 1,069), pre-diabetes (n = 412), or diabetes (n = 157). Orthostatic hypotension was defined as a decline in systolic/diastolic blood pressure of > or =20/10 mmHg when an individual changed from a supine to a standing position. The cardiovagal response to standing was the ratio between the longest RR interval around beat 30 and the shortest RR interval around beat 15 after standing (30 max-to-15 min ratio).

RESULTS

The prevalences of orthostatic hypotension were 13.8, 17.7, and 25.5% in subjects with NGT, pre-diabetes, and diabetes, respectively. For all subjects, age, diabetes, hypertension, and a decreased 30 max-to-15 min ratio, but not pre-diabetes, were independently associated with orthostatic hypotension. Age, hypertension, and 30 max-to-15 min ratio were the correlates of orthostatic hypotension in NGT subjects. Age and hypertension were related to orthostatic hypotension in pre-diabetic subjects. A1C and hypertension were the determinants of orthostatic hypotension in diabetic subjects. Supine blood pressure was related to orthostatic hypotension in all subjects and subgroups.

CONCLUSIONS

Pre-diabetic subjects do not have a higher risk of orthostatic hypotension than subjects with NGT, although the risk of orthostatic hypotension is higher in diabetic subjects. Hypertension and supine blood pressure were risk factors for orthostatic hypotension in both pre-diabetic and diabetic subjects. Age and A1C were the correlates of orthostatic hypotension in pre-diabetic and diabetic subjects, respectively. The cardiovagal response to standing is an important determinant of orthostatic hypotension in subjects with NGT but not in pre-diabetic and diabetic subjects.

Clinical Features of Elderly Patients Submitted to Coronary Artery Bypass Graft

OBJECTIVE

To describe the clinical features as well as morbidity and mortality of elderly patients submitted to coronary artery bypass graft (CABG).

DESIGN

Randomized, single-center, observational study.

METHODS

A prospective study was carried out in a tertiary referral teaching hospital (Heart Institute-Brazil). A total of 220 inpatients submitted to elective CABG were evaluated and data collected from the pre-, intra- and postoperative periods.

INSTRUMENTS

The patients were assessed according to the Geriatric Depression Scale. A diagnosis of delirium was determined according to DSM-IV criteria.

RESULTS

Of these 220 patients 64.5% were males and 35.5% females. The mean age was 71 years. The most important preoperative findings were a higher incidence of comorbidities such as hypertension (73%), diabetes mellitus (35%), dyslipidemia (27%), and previous myocardial infarction (41%). The majority of patients were found to have three or more vessels obstructed at angiography (74%). The major intraoperative findings were that a high number of the patients received more than 3 grafts (74%). A large proportion (72%) of patients needed a blood transfusion and the overall incidence of clinical complications was 33%. The overall postoperative mortality rate for this observational study was 5%. A large number of patients presented complications (56%) such as hypotension (22%), atrial fibrillation (22%), and delirium (34%).

CONCLUSIONS

Although elderly patients have a somewhat increased, however acceptable, operative mortality rate, we believe that this patient group can benefit from CABG.

Normative data on phases of the Valsalva maneuver

The phases of the Valsalva maneuver have well-known pathophysiology, and are used in the evaluation of adrenergic function. Because scant normative data is available, we have evaluated normative data for the Valsalva maneuver in control subjects. The patient, supine, performed the Valsalva maneuver maintaining an expiratory pressure of 40 mm Hg for 15 seconds. We reviewed 188 Valsalva maneuver recordings of normal control subjects, and recordings were excluded if two reproducible recordings were not obtained, or if expiratory pressure was <30 mm Hg or < 10 seconds. One hundred and three recordings were acceptable for analysis; 47 female and 56 male subjects, age in years (mean +/- SD) was 52.2+/-17.3 and 44.8+/-17.3, respectively. The association of expiratory pressure with age (P < 0.001) and gender ( P < 0.001) was complex, expressed as a parabola in both men and women, but resulted in phases I and III that were not significantly different. An increase in age resulted in a progressively more negative phase II_E (P < 0.05) and attenuation of phase II_L (P < 0.01). An increase in supine blood pressure resulted in a significantly more negative phase II_E (P < 0.001) and a lower phase IV. Phase IV is unaffected by age and gender.

Effect of age and gender on sudomotor and cardiovagal function and blood pressure response to tilt in normal subjects

Normative data are limited on autonomic function tests, especially beyond age 60 years. We therefore evaluated these tests in a total of 557 normal subjects evenly distributed by age and gender from 10 to 83 years. Heart rate (HR) response to deep breathing fell with increasing age. Valsalva ratio varied with both age and gender. QSART (quantitative sudomotor axon-reflex test) volume was consistently greater in men (approximately double) and progressively declined with age for all three lower extremity sites but not the forearm site. Orthostatic blood pressure reduction was greater with increasing age. HR at rest was significantly higher in women, and the increment with head-up tilt fell with increasing age. For no tests did we find a regression to zero, and some tests seem to level off with increasing age, indicating that diagnosis of autonomic failure was possible to over 80 years of age.