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Beat-to-beat (B2B) variability in biomedical signals has been shown to have high diagnostic power in the treatment of various cardiovascular and autonomic disorders. In recent years, new techniques and devices have been developed to enable non-invasive blood pressure (BP) measurements. In this work, we aim to establish the concept of two-dimensional signal warping, an approved method from ECG signal processing, for non-invasive continuous BP signals. To this end, we introduce a novel BP-specific beat annotation algorithm and a B2B-BP fluctuation (B2B-BPF) metric novel for BP measurements that considers the entire BP waveform. In addition to careful validation with synthetic data, we applied the generated analysis pipeline to non-invasive continuous BP signals of 44 healthy pregnant women (30.9 ± 5.7 years) between the 21st and 30th week of gestation (WOG). In line with established variability metrics, a significant increase (p < 0.05) in B2B-BPF can be observed with advancing WOGs. Our processing pipeline enables robust extraction of B2B-BPF, demonstrates the influence of various factors such as increasing WOG or exercise on blood pressure during pregnancy, and indicates the potential of novel non-invasive biosignal sensing techniques in diagnostics. The results represent B2B-BP changes in healthy pregnant women and allow for future comparison with those signals acquired from women with hypertensive disorders. [ABSTRACT FROM AUTHOR]

Beat-to-beat (B2B) variability in biomedical signals has been shown to have high diagnostic power in the treatment of various cardiovascular and autonomic disorders. In recent years, new techniques and devices have been developed to enable non-invasive blood pressure (BP) measurements. In this work, we aim to establish the concept of two-dimensional signal warping, an approved method from ECG signal processing, for non-invasive continuous BP signals. To this end, we introduce a novel BP-specific beat annotation algorithm and a B2B-BP fluctuation (B2B-BPF) metric novel for BP measurements that considers the entire BP waveform. In addition to careful validation with synthetic data, we applied the generated analysis pipeline to non-invasive continuous BP signals of 44 healthy pregnant women (30.9 ± 5.7 years) between the 21st and 30th week of gestation (WOG). In line with established variability metrics, a significant increase (p < 0.05) in B2B-BPF can be observed with advancing WOGs. Our processing pipeline enables robust extraction of B2B-BPF, demonstrates the influence of various factors such as increasing WOG or exercise on blood pressure during pregnancy, and indicates the potential of novel non-invasive biosignal sensing techniques in diagnostics. The results represent B2B-BP changes in healthy pregnant women and allow for future comparison with those signals acquired from women with hypertensive disorders.

Background: Older adults with hypertension often had diminished walking performance. The underlying mechanism through which hypertension affects walking performance, however, has not been fully understood. We here measured the complexity of the continuous systolic (SBP) and diastolic (DBP) blood pressure fluctuation, grade of white matter lesions (WMLs), and cognitive function and used structural equation modeling (SEM) to examine the interrelationships between hypertension, BP complexity, WMLs, cognitive function, and walking speed in single- and dual-task conditions.Methods: A total of 152 older adults with age > 60 years (90 hypertensive and 62 normotensive participants) completed one MRI scan of brain structure, a finger BP assessment of at least 10 min, Mini-Mental State Examination (MMSE) to assess cognitive function, and 10-meter walking tests in single (i.e., normal walking) and dual tasks (i.e., walking while performing a serial subtraction of three from a random three-digit number). The grade of WMLs was assessed using the total score of Fazekas scale; the complexity of SBP and DBP was measured using multiscale entropy (MSE), and the walking performance was assessed by walking speed in single- and dual-task conditions.Results: As compared to normotensives, hypertensive older adults had significantly slower walking speed, lower complexity of SBP and DBP, greater grade of WMLs, and poorer cognitive function (p < 0.03). Those with lower BP complexity (β > 0.31, p < 0.003), greater WML grade (β < −0.39, p < 0.0002), and/or poorer cognitive function (β < −0.39, p < 0.0001) had slower walking speed in single- and/or dual-task conditions. The SEM model demonstrated significant total effects of hypertension on walking speed, and such effects were mediated by BP complexity only, or BP complexity, WML grade, and cognitive function together.Conclusion: This study demonstrates the cross-sectional association between the complexity of continuous beat-to-beat BP fluctuation, WML grade, cognitive function, and walking speed in hypertensive and normotensive older adults, revealing a potential mechanism that hypertension may affect walking performance in older adults through diminished BP complexity, increased WML grade, and decreased cognitive function, and BP complexity is an important factor for such effects. Future longitudinal studies are warranted to confirm the findings in this study.

Background: Older adults with hypertension often had diminished walking performance. The underlying mechanism through which hypertension affects walking performance, however, has not been fully understood. We here measured the complexity of the continuous systolic (SBP) and diastolic (DBP) blood pressure fluctuation, grade of white matter lesions (WMLs), and cognitive function and used structural equation modeling (SEM) to examine the interrelationships between hypertension, BP complexity, WMLs, cognitive function, and walking speed in single- and dual-task conditions. Methods: A total of 152 older adults with age > 60 years (90 hypertensive and 62 normotensive participants) completed one MRI scan of brain structure, a finger BP assessment of at least 10 min, Mini-Mental State Examination (MMSE) to assess cognitive function, and 10-meter walking tests in single (i.e., normal walking) and dual tasks (i.e., walking while performing a serial subtraction of three from a random three-digit number). The grade of WMLs was assessed using the total score of Fazekas scale; the complexity of SBP and DBP was measured using multiscale entropy (MSE), and the walking performance was assessed by walking speed in single- and dual-task conditions. Results: As compared to normotensives, hypertensive older adults had significantly slower walking speed, lower complexity of SBP and DBP, greater grade of WMLs, and poorer cognitive function (p < 0.03). Those with lower BP complexity (β > 0.31, p < 0.003), greater WML grade (β < −0.39, p < 0.0002), and/or poorer cognitive function (β < −0.39, p < 0.0001) had slower walking speed in single- and/or dual-task conditions. The SEM model demonstrated significant total effects of hypertension on walking speed, and such effects were mediated by BP complexity only, or BP complexity, WML grade, and cognitive function together. Conclusion: This study demonstrates the cross-sectional association between the complexity of continuous beat-to-beat BP fluctuation, WML grade, cognitive function, and walking speed in hypertensive and normotensive older adults, revealing a potential mechanism that hypertension may affect walking performance in older adults through diminished BP complexity, increased WML grade, and decreased cognitive function, and BP complexity is an important factor for such effects. Future longitudinal studies are warranted to confirm the findings in this study. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the properties of blood pressure (BP) fluctuation and sympathovagal imbalance with the severity of OSAS. Methods: Nocturnal BP was continuously monitored by polysomnography for mild (n = 33), moderate (n = 34), and severe (n = 37) OSAS patients. Apnea-related systolic BP elevation (△SBP) indicated the amplitude of BP fluctuation. The SBP index, number of △SBP > 10 mmHg/h of sleep, indicated the frequency of significant BP fluctuations. The low frequency/high frequency (LF/HF) ratios indicated heart rate variability and sympathovagal imbalance. Results: △SBP and the SBP index were the highest in severe OSAS (12.9 ± 2.3 mmHg and 33.7 ± 14.7/h), followed by moderate OSAS (9.5 ± 2.6 mmHg and 7.1 ± 4.4/h), and mild OSAS (8.3 ± 1.6 mmHg and 3.4 ± 2.1/h). The LF/HF ratios in severe OSAS were significantly higher than that in moderate and mild OSAS. In mild OSAS, arousal played a more important role in BP fluctuation. In moderate OSAS, the oxygen desaturation index (ODI) and the SBP index were correlated. The difference in △SBP induced by hypoxia or by arousal was not significant. In severe OSAS, the apnea-hypopnea index (AHI) and LF/HF ratio were correlated with the SBP index, and △SBP was larger with hypoxia than arousal. Conclusions: BP fluctuation and sympathovagal imbalance were both related to obstructive sleep apnea severity. The influence of arousal and hypoxia on BP fluctuation varied with OSAS severity. Trial registration: NCT02876471 [ABSTRACT FROM AUTHOR]

Purpose: Obstructive sleep apnea syndrome (OSAS) can induce dramatic blood pressure (BP) fluctuations during sleep and it can be associated with hypertension. We investigated the properties and associated influential factors of BP fluctuation in severe OSAS with and without hypertension.Methods: Two hundred one severe OSAS subjects were divided into hypertensive and normotensive groups. BP was continuously monitored via measurement of pulse transmit time (PTT). The value of apnea-related systolic BP elevation (ΔSBP) was used to reflect the amplitude of BP fluctuation, and the SBP index (the number of ΔSBP > 10 mmHg per hour of sleep time) was used to stand for the frequency of significant BP fluctuations.Results: Compared with the normotensive group, △SBP and SBP index were higher in the hypertensive group (13.8 ± 4.4 mmHg vs 10.9 ± 3.1 mmHg; 44.8 ± 21.3 events/h vs 26.8 ± 15.8 events/h, all p < 0.001). Multiple regression analysis showed that percentage of sleep time with oxygen saturation < 90% (TST90) and SBP index correlated more with mean level of awakeness and sleep SBP than with apnea-hypopnea index (AHI). Analysis of all apnea events demonstrated that △SBP and the frequency of BP fluctuations were more remarkable following hypoxia than following arousal; △SBP correlated more with oxygen desaturation degree (r = 0.388, p < 0.01) and minimal SpO2 (r = 0.392, p < 0.01) than with apnea length and desaturation duration.Conclusions: In severe OSAS, nocturnal and awake BP levels are associated more with the nocturnal hypoxic duration and BP fluctuation than with AHI. Nocturnal BP fluctuation can be induced by both hypoxia and arousal, and especially by hypoxia.Trial registration: NCT02876471 [ABSTRACT FROM AUTHOR]

Summary: Objective: Pheochromocytoma surgery carries a high risk of haemodynamic instability (HI). However, there are few studies investigating the risk factors for HI for pheochromocytoma surgery in a Chinese population. Therefore, our objective was to identify preoperative risk factors for HI during surgery in a Chinese population with pheochromocytoma. Patients and methods: In this retrospective study, 134 patients undergoing surgery for pheochromocytoma at a single university‐affiliated hospital between November 2002 and July 2017 were enrolled. Demographics, comorbidities, preoperative medical preparation, operation details and perioperative haemodynamics of these patients were retrospectively collected and analysed. Multivariable logistic regression analysis was performed to identify the preoperative risk factors for intraoperative HI. Results: 32.8% (44/134) patients suffered from intraoperative HI. According to the result of multivariate analysis, tumour diameter >50 mm (odds ratio [OR] 2.526; 95% confidence interval [CI] 1.163–5.485; P = .019), diabetes/prediabetes (OR 2.251; 95% CI 1.039–4.876; P = .040) and preoperative systolic blood pressure fluctuation >50 mm Hg (OR 3.163; 95% CI 1.051–9.522, P = .041) were independent predictors for intraoperative HI. The observed incidence of HI was 8.9%, 42.6%, 47.8% and 60% when zero, one, two or three risk factors were present, respectively. Conclusions: HI is common among Chinese patients undergoing surgery for pheochromocytoma. Our study identified three predictive factors for intraoperative HI: a large tumour diameter, diabetes/prediabetes and a great preoperative systolic blood pressure fluctuation. Furthermore, patients are more likely to suffer from HI when they have more predictive risk factors. Identification of these risk factors can help to improve perioperative management. [ABSTRACT FROM AUTHOR]

Background and objective Autonomic disturbances and sleep problems are common non-motor symptoms in patients with Parkinson's disease (PD). Orthostatic hypotension, supine hypertension (SH), and nocturnal hypertension (NH) are inter-related in patients with PD. These abnormalities might be associated with restless legs syndrome (RLS), which occurs predominantly at rest or during sleep. Few reports have suggested an association between circadian blood pressure disturbances and RLS in the general population. We evaluated the relationship between neurocardiovascular blood pressure alterations and RLS in patients with early PD. Methods A total of 225 patients, newly diagnosed with PD, were included in the study. RLS was diagnosed by the International Restless Legs Syndrome Study Group's diagnostic criteria. Orthostatic vital signs and ambulatory 24-h blood pressure were monitored and recorded. Results Thirty-six (16.0%) participating patients had RLS. SH and NH were more frequent in the PD + RLS group than in the group without RLS. Supine blood pressure, orthostatic decline in blood pressure, nighttime blood pressure, and the standard deviation of systolic blood pressure were significantly higher in the PD + RLS group than in the group without RLS. Conclusion RLS is related to nocturnal/supine hypertension and blood pressure fluctuations, suggesting a neuropathological association between autonomic and sleep dysfunctions in patients with PD. RLS may be a determinant of neurocirculatory abnormalities. Detecting and effectively treating RLS might slow the rate of pressure-related neurocardiovascular damage in dysautonomic patients with PD. [ABSTRACT FROM AUTHOR]

Background: Cardiovascular morphological changes are often conspicuous in autopsy examination of chronic hemodialysis (HD) patients. On the other hand, the fluctuation pattern in blood pressure (BP) during HD treatment varies from one patient to another. Cardiovascular changes may correlate with clinical findings including BP fluctuation patterns during HD, although no autopsy studies have previously examined this issue. Methods: In this study, 53 autopsies of patients who had been on chronic HD were reviewed. We determined the relationship between BP fluctuation during HD treatment along with stable and cardiovascular morphology, including heart weight, ventricular wall thickness, circumferences of the valves and the severity of aortic arteriosclerosis and coronary stenosis. Patients were divided into 4 groups according to the pattern of BP fluctuation during HD treatment at about 6 months before death: group 1 (n = 13), symptomatic hypotension and/or decline pattern during HD; group 2 (n = 11), continuously high BP during HD treatment; group 3 (n = 17), continuous normal BP during HD treatment, and group 4 (n = 12), continuously low BP without symptomatic hypotension during HD treatment. Results: Heart weight and ventricular wall thickness were greatest in group 2. The scores for aortic arteriosclerosis in groups 1 and 2 were higher than in groups 3 and 4. The coronary stenosis index was significantly higher in group 1 than in the other groups, and that in group 2 was higher than in group 4. Multiple regression analysis showed that age, HD duration and pulse pressure were independent variables for the score of arteriosclerosis, and the decline pattern of BP fluctuation during HD and pulse pressure were independent variables for coronary stenosis index. Conclusions: Our results suggest that certain clinical parameters including BP during HD may reflect cardiovascular morphological changes in stable HD patients, although further examination, such as 24-hour blood pressure measurement is recommended to elucidate the pathophysiology of cardiovascular diseases in HD patients.Copyright © 2001 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]