Pressure Measurements Research Articles

Transforming Hypertension Diagnosis and Management in The Era of Artificial Intelligence: A 2023 National Heart, Lung, and Blood Institute (NHLBI) Workshop Report.

Hypertension is among the most important risk factors for cardiovascular disease, chronic kidney disease, and dementia. The artificial intelligence (AI) field is advancing quickly, and there has been little discussion on how AI could be leveraged for improving the diagnosis and management of hypertension. AI technologies, including machine learning tools, could alter the way we diagnose and manage hypertension, with potential impacts for improving individual and population health. The development of successful AI tools in public health and health care systems requires diverse types of expertise with collaborative relationships between clinicians, engineers, and data scientists. Unbiased data sources, management, and analyses remain a foundational challenge. From a diagnostic standpoint, machine learning tools may improve the measurement of blood pressure and be useful in the prediction of incident hypertension. To advance the management of hypertension, machine learning tools may be useful to find personalized treatments for patients using analytics to predict response to antihypertension medications and the risk for hypertension-related complications. However, there are real-world implementation challenges to using AI tools in hypertension. Herein, we summarize key findings from a diverse group of stakeholders who participated in a workshop held by the National Heart, Lung, and Blood Institute in March 2023. Workshop participants presented information on communication gaps between clinical medicine, data science, and engineering in health care; novel approaches to estimating BP, hypertension risk, and BP control; and real-world implementation challenges and issues.

Validation of the DBP-8278B Wrist-type Fully Automatic Blood Pressure Monitor in the general population according to the ISO 81060-2:2018/AMD 1:2020 protocol.

The aim of this study was to evaluate the accuracy of the DBP-8278B Wrist-type Fully Automatic Blood Pressure Monitor in the general population according to the AAMI/ESH/ISO Universal Standard (ISO 81060-2 : 2018/AMD 1 : 2020). The test monitor was used to measure SBP and DBP and pulse rate in the wrists using the oscillometric method. According to this protocol using the same-arm sequential blood pressure measurement method, subjects were recruited to fulfill the age, sex, blood pressure, and cuff distribution criteria of the Universal Standard. A single cuff for wrist sizes of 13.5-21.5 cm was used. A total of 85 subjects were included in this study. According to Criterion 1, the mean difference in SBP between the test device and the reference device was 0.89 mmHg, with a SD of 7.76 mmHg. The mean difference of DBP was -1.44 mmHg, with a SD of 6.23 mmHg. The mean difference between SBP and DBP was less than 5.0 mmHg, and the SD was less than 8.0 mmHg, which met the requirements. According to Criterion 2, the SD of the mean differences of SBP between the test device and the reference device per subject was 5.65 mmHg, which was less than 6.88 mmHg and met the requirements. The SD of the mean differences of DBP between the test device and the reference device per subject was 5.61 mmHg, which was less than 6.78 mmHg and met the requirements. The DBP-8278B Wrist-type Fully Automatic Blood Pressure Monitor met the requirements of the AAMI/ESH/ISO Universal Standard (ISO 81060-2 : 2018/AMD 1 : 2020). It can be recommended for home and clinical use.

Real world treatment of hypertension on hemodialyses-data from large Polish database.

The prevalence of hypertension among patients with end stage kidney disease (ESKD) undergoing hemodialysis (HD) ranges from 72-88% depending on applied diagnostic criteria and chosen method of blood pressure measurement. Despite the guidelines recommending the widespread use of renin angiotensin system blockers (RASB) in patients with kidney disease, their utilization in patients on HD may be suboptimal, especially in patients with preserved diuresis. This hesitance often steams from concern is often due to fear of a decrease in eGFR and a subsequent decrease in diuresis. The aim of this study was to compare clinical characteristics, blood pressure, safety, and hemodialysis adequacy indices in hypertensive HD patients on multiple antihypertensive drug regimens, including diuretic treated with RASB (RASB group) or without RASB (no-RASB) with preserved residual diuresis. We sought to examine the real life use of RASB in hemodialysis patients in relation to their clinical characteristics, blood pressure, safety, and hemodialysis adequacy. From a database of 5879 patients receiving hemodialysis (mean age 65.2±14.2 yrs., 60% of males) of the largest provider of HD in the country, we selected the subgroup treated with at least three antihypertensive medications including diuretics. We compared patients treated with RASB to counterparts without RASB (no-RASB). RASB group has similar age and gender proportions as well as BMI and bioimpedance,compared to counterparts. However, dry body mass was significantly lower in the RASB group (78.1±18.3 kg vs. 80.0±18.2 kg, p<0.017). Prevalence of diabetes mellitus was similar in both groups, but RASB-treated patients have cardiovascular diseases more frequently (70.1% vs. 60.8%; p<0.001). Systolic blood pressure and the number of antihypertensive drugs used were significantly higher in RASB patients than in counterparts (146±16 mmHg vs. 144±15 mmHg; p<0.001 and 4.1±0.9 vs. 3.5±0.5; p<0001 respectively). RASB-treated patients have significantly longer dialysis vintage (52.7±44.4 months vs. 40.2±40.9 months; p<0.001) and dialysis time (722±87.1 min./week vs. 713±93.4 min./week;p<0.017) than counterparts. Serum potassium was slightly but significantly higher in RASB (5.3±0.8 mmol/L vs. 5.1±0.7 mmol/L;p<0.01). In the real world setting, RASB can be safely used in HD patients treated with diuretics with preserved residual diuresis. Given that many HD patients present numerous multimorbidities, RASB should not only be considered as an additional hypotensive drug in poorly controlled hypertension but also in other compelling indications in HD patients. The tendency toward hyperkalemia in HD patients could be effectively managed with appropriate diet and HD prescription adjustments.

Observing and Modeling Short‐Term Changes in Basal Friction During Rain‐Induced Speed‐Ups on an Alpine Glacier

AbstractBasal shear stress on hard‐bedded glaciers results from normal stress against bed roughness, which depends on basal water pressure and cavity size. These quantities are related in a steady state but are expected to behave differently under rapid changes in water input, which may lead to a transient frictional response not captured by existing friction laws. Here, we investigate transient friction using Global Positioning System vertical displacement and horizontal velocity observations, basal water pressure measurements, and cavitation model predictions during rain‐induced speed‐up events at Glacier d'Argentière, French Alps. We observe up to a threefold increase in horizontal surface velocity, spatially migrating at rates consistent with subglacial flow drainage, and associated with surface uplift and increased water pressure. We show that frictional changes are mainly driven by changes in water pressure at nearly constant cavity size. We propose a generalized friction law capable of capturing observations in both the transient and steady‐state regimes.

Patient experiences with blood pressure measurement methods for hypertension diagnosis: Qualitative findings from the BP-CHECK study.

Out-of-office blood pressure (BP) measurement is recommended when making a new hypertension diagnosis. In practice, however, hypertension is primarily diagnosed using clinic BP. The study objective was to understand patient attitudes about accuracy and patient-centeredness regarding hypertension diagnostic methods. Qualitative study within a randomized controlled diagnostic study conducted between May 2017 and March 2019 comparing the accuracy and acceptability of BP measurement methods among patients in an integrated healthcare delivery system. All participants completed 24-hour ambulatory blood pressure monitoring (ABPM), plus either clinic BP, home BP monitoring (HBPM), or kiosk BP diagnostic testing. Qualitative interviewees (aged 31-76 years, n=35) were recruited from the main study. Participants who completed HBPM found it to be comfortable and low burden, and believed it produced accurate results. Participants in the clinic arm described clinic measurements as inconvenient. Participants in the kiosk arm overall did not favor kiosks due to concerns about accuracy and privacy. Participants described ABPM as the most accurate method due to repeated measurements over the 24-hour period in real-world contexts, but many found it uncomfortable and disruptive. Participants also noted methods that involved repeated measures such as HBPM and ABPM particularly influenced their understanding of whether or not they had hypertension. Hypertension diagnostic methods that include more BP measurements help patients gain a deeper understanding of BP variability and the lower reliability of infrequent measurements in clinic. These findings warrant implementing strategies to enhance out-office BP diagnostic testing in primary care.

Prevalence of interarm blood pressure difference is notably higher in women; the Viborg population-based screening program (VISP)

BackgroundBilateral blood pressure (BP) measurement is important in cardiovascular prevention for identifying systolic interarm BP difference (IAD) and hypertension. We investigated sex-stratified IAD prevalence and its associations and coexistence with screen-detected peripheral atherosclerosis and hypertension. Furthermore, we determined the proportion misclassified as non-hypertensive when using the lower versus the higher reading arm.MethodsThis sub-study formed part of the Viborg Screening Program (VISP), a cross-sectorial population-based cardiovascular screening programme targeting 67-year-old Danes. VISP includes screening for peripheral atherosclerosis (lower extremity arterial disease and carotid plaque), abdominal aortic aneurysm, hypertension, diabetes mellitus, and cardiac disease. Self-reported comorbidities, risk factors, and medication use were also collected. Among 4,602 attendees, 4,517 (82.1%) had eligible bilateral and repeated BP measurements. IAD was defined as a systolic BP difference ≥ 10 mmHg. IAD-associated factors (screening results and risk factors) were estimated by logistic regression; proportional coexistence was displayed by Venn diagrams (screening results).ResultsWe included 2,220 women (49.2%) and 2,297 men (50.8%). IAD was more predominant in women (26.8%) than men (21.0%) (p < 0.001). This disparity persisted after adjustment [odds ratio (OR) 1.53; 95% confidence interval (CI) 1.32–1.77]. No other association was recorded with the conditions screened for, barring potential hypertension: BP 140–159/90–99 mmHg (OR 1.68, 95% CI 1.44–1.97) and BP ≥ 160/100 mmHg (OR 1.82, 95% CI 1.49–2.23). Overall, IAD and BP ≥ 160/100 mmHg coexistence was 4% in women and 5% in men; for BP ≥ 140/90 mmHg, 13% and 14%, respectively. Among those recording a mean BP ≥ 140/90 mmHg in the higher reading arm, 14.5% of women and 15.3% of men would be misclassified as non-hypertensive compared with the lowest reading arm.ConclusionFemale sex was an independent factor of IAD prevalence but not associated with other arterial lesions. Approximately 15% needed reclassification according to BP ≥ 140/90 mmHg when the lower rather than the higher reading arm was used; verifying bilateral BP measurements improved detection of potential hypertension. In future, the predictive value of sex-stratified IAD should be assessed for cardiovascular events and death to verify its potential as a screening tool in population-based cardiovascular screening.Trial registration for VISPNCT03395509:10/12/2018.

Intraocular pressure measurement and association with corneal biomechanics in patients underwent Descemet’s stripping with endothelial keratoplasty: a comparative study

Intraocular pressure measurement and association with corneal biomechanics in patients underwent Descemet’s stripping with endothelial keratoplasty: a comparative study

Wearable cuffless blood pressure tracking: when will they be good enough?

Wearable health monitoring is a multibillion-dollar industry. But the holy grail is probably getting it right for blood pressure monitoring without a cuff, because raised blood pressure is very common and the leading cause of death in the world. Many have tried and failed, but industry is persisting: numerous cuffless wearable blood pressure devices are on the market, several technologies have been developed, hundreds of patents are registered every year, and some devices already have regulatory approval. However, to convince the die-hard blood pressure critic is a different ball game. To understand the challenges of currently accepted methods and cuffless devices, I performed a 24-h blood pressure monitoring self-test, including measurements when awake, asleep and watching an intense match of the Rugby World Cup final, with the purpose to demonstrate the challenges and opportunities we face. Blood pressure was monitored using five different devices simultaneously: validated left and right arm cuff blood pressure, and three cuffless wearable devices (wrist-band, chest patch and a ring). Whilst none of these devices proved to be perfect in capturing a physiologically challenging measure, namely blood pressure, it emphasised that our current practice of a single blood pressure measurement in clinical practice should be revisited. It further begs the question of when cuffless measurements will be good enough to incorporate in clinical decision-making.

Correlation between arousal threshold and occurrence of hypertension in patients with obstructive sleep apnea hypopnea syndrome

Objective: To investigate the relationship between arousal threshold (ArTH) and hypertension in patients with obstructive sleep apnea hypopnea syndrome (OSA). Methods: This study recruited 648 patients diagnosed with OSA at the Sleep Center of the Second Affiliated Hospital of Soochow University from January 2020 to August 2021, including 569 males and 79 females, aged 42(35,52) years. The basic demographic information and clinical data of all patients were collected, including blood pressure measurement, and relevant questionnaire scores, and nocturnal polysomnography (PSG) parameters. A clinical predictive model based on sleep apnea hypopnea index (AHI), lowest pulse oxygen saturation (LSpaO2) and hypopnea ratio (FHypopneas) was used to access the arousal threshold of OSA patients. Patients were divided into OSA group and OSA with hypertension group according to whether they were combined with hypertension. The differences in the above indexes between the two groups were analyzed to explore the relationship between arousal threshold and hypertension in OSA patients, using a binary logistic stepwise regression analysis. Results: A total of 648 OSA patients were enrolled, including 415 in the OSA with hypertension group and 233 in the OSA group. Compared with OSA group, OSA with hypertension group had older age, higher body mass index (BMI), higher blood pressure at bedtime and at awakening, higher AHI and lower proportion of hypopnea (all P<0.05). There were no significant differences between other general data and PSG parameters (all P>0.05). The proportion of patients with low arousal threshold (AHI<30 events per hour, LSpO2>82.5%, Fhypopneas>58.3%) in OSA with hypertension group was lower, and the proportion of phenotypic patients with low arousal threshold was significantly lower (30.1% vs. 52.4% P<0.001). Binary logistic stepwise regression analysis showed that the high arousal threshold (OR=1.930, 95%CI:1.326-2.808, P=0.001) was an independent risk factor for OSA complicated with hypertension. Conclusion: The arousal threshold is associated with the development of hypertension in OSA patients, and OSA patients with a high arousal threshold have a higher risk of developing hypertension.

Arterial hypertension after liver transplantation.

One of the most prevalent influenceable risk factors for poor cardiovascular outcome is arterial hypertension.This is aprospective analysis of liver transplant recipients in which 24-hour blood pressure (BP) measurement was performed. The primary aim was to identify post-LT (liver transplantation) patients without ahistory of arterial hypertension who meet the criteria for arterial hypertension using 24-hour BP monitoring. Secondary objectives were to determine how many patients with known treated arterial hypertension had suboptimal BP control. The group included 88 patients (men, 52.3%, history of arterial hypertension group: n=56, no history of arterial hypertension group: n=32) with an average age at the time of measurement of 62.4 years±11. The average time since LT at the time of measurement was 45.2 months. De novo arterial hypertension using 24-hour BP monitoring was diagnosed in 28%. Hypertonic changes in the fundus oculi were confirmed as predictor for suboptimally controlled hypertension [OR 5,1265, p=0.0279]. On the other hand, male sex [OR 3.1840, p=0.0311], together with age [OR 1.3347, p=0.0153] and waist circumference [OR 4.3490, p=0.0418] predicted the need of intensification of antihypertensive treatment. Male sex, age and waist circumference should increase the index of suspicion and lead to zoom-in on apossibility of poorly controlled blood pressure. Where automated blood pressure monitoring is unavailable, regular examination of the fundus could serve as an available surrogate marker of suboptimally controlled arterial hypertension (Tab.6, Fig. 1, Ref. 36). Text in PDF www.elis.sk Keywords: liver transplantation, arterial hypertension, automated blood pressure monitoring.

Influence of implantable Collamer lens implantation on choroidal thickness and blood flow density

Objective: To observe the impact of implantable Collamer lens (ICL) implantation surgery on choroidal thickness and blood flow density in myopic patients. Methods: This was a prospective cohort study. Patients undergoing ICL surgery at Qingdao University Affiliated Hospital between June 2021 and May 2023 were consecutively enrolled. Patients were categorized into high myopia (HM) and super high myopia (SHM) groups based on whether their spherical equivalence power exceeded 10.00 D. Comprehensive ophthalmic examinations, including optical coherence tomography, optical coherence tomography angiography, visual acuity assessment, intraocular pressure measurement, and optometry, were performed preoperatively and at 1 week, 1 month, and 3 months postoperatively. Results: A total of 42 patients (84 eyes), with an average age of (25.27±3.18) years, comprising 11 males and 31 females, were enrolled in the study. Among them, 20 patients belonged to the HM group, while 22 patients were in the SHM group. Both choroidal thickness and blood flow density exhibited significant increases at postoperative 1 week and 1 month compared to preoperative levels (P<0.05), but returned to baseline levels by postoperative 3 months. Specifically, the subfoveal choroidal thickness increased from (169.49±61.57) μm preoperatively to (180.16±66.61) μm at 1 week, (186.69±63.32) μm at 1 month, and then reverted to (169.58±60.82) μm at 3 months. The central choroidal blood flow density showed changes from 60.03%±1.60% preoperatively to 61.04%±1.17% at 1 week, 60.42%±1.81% at 1 month, and 60.22%±1.57% at 3 months. Furthermore, the HM group exhibited more pronounced changes in both choroidal thickness and blood flow density across all time points compared to the SHM group. Significant differences were observed in choroidal thickness changes at various areas at 1 month, while changes in blood flow density in specific areas were significant. However, no significant differences were noted at 3 months postoperatively. Correlation analysis revealed a negative correlation of changes in subfoveal choroidal thickness and central choroidal blood flow density postoperatively at 1 week and 3 months with preoperative choroidal blood flow density. Notably, no correlation was found between preoperative choroidal thickness and postoperative changes. Conclusions: In the early period following ICL implantation, the increase in choroidal thickness and blood flow density may be more pronounced in HM compared to SHM, but the two parameters can return to baseline levels by 3 months. ICL implantation transiently affects the fundus microenvironment in myopic patients, with implications of preoperative choroidal blood flow.

Why are continent catheterizable channels continent? A stomal pressure profilometry feasibility study.

A continent catheterizable channel (CCC) may be a solution for patients with impaired bladder emptying and difficult transurethral access. Leakage of the CCC is a common complication. To prevent leakage, the pressure in the CCC has to be higher than the reservoir (bladder/pouch) pressure in at least one location. It has not been clearly defined through which mechanism(s) the CCC achieves continence. In this feasibility study, we measured the CCC pressure profile in adult patients with various types of CCC's with and without stomal leakage. Adult patients with a CCC on a (augmented) bladder or pouch who underwent a urodynamic investigation between January and March 2023 were included. Next to the standard urodynamic investigation, a continuous stomal pressure measurement (CSP) and stomal pressure profilometry with empty bladder (SPP-1) and with filled bladder (SPP-2) of the CCC were performed. A total of 17 patients were included. It was technically possible to perform SPP-1 and SPP-2 in all patients, and to measure the CSP in 16/17 patients. The median maximum stomal pressures in SPP-1 and SPP-2 were 112 (interquartile range [IQR], 76-140) cmH2O and 120 (IQR, 92-140) cmH2O, respectively. Nine patients had stomal leakage during the urodynamic investigation. In five patients, the detrusor leak point pressure (dLPP) was low (<20 cmH2O). A pressure peak at the beginning of SPP-2 was absent in all patients with stomal leakage at low dLPP. SPP and CSP measurement in CCCs are feasible. We found differences in SPP-2 between patients with and without leakage at low dLPP, indicative of a role of the intravesical tunnel in continence or high dLPP. The results of this study may improve our understanding of the physiology and dynamics of CCCs as well as the management of CCC-related complications.

Clinical Profile of Ocular Trauma at a Tertiary Care Hospital

Background: Ocular trauma is preventable and one of the leading causes of ocular morbidity and blindness. Approximately 6 million people are blind from eye injuries, 2.3 million with bilateral visual impairment and 19 million with unilateral visual loss worldwide. In developing countries like ours the incidence of eye injuries is very high. This study has been conducted in the view of public health importance to provide information on magnitude, clinical and epidemiological profile of ocular injuries. Methods: A hospital based, cross sectional observational study, conducted during September 2014 - March 2016 in tertiary care center in Jharkhand, all cases of ocular trauma were included in the study. Demographic profile (age, sex, locality, occupation), nature and cause of injury was recorded. Detailed ophthalmological examination including visual acuity, slit lamp examination, indirect ophthalmoscopy, B-scan, intraocular pressure measurement, gonioscopy, computed tomography brain with orbit, Magnetic Resonance Imaging, X-Ray were done in relevant cases. Results: Total of 948 patients of ocular trauma were included. Most patients belong to the age group 21-40 years (60.87%), with mean age of 29.79 + 16.47 years. Males were affected more (73.52%) than females (26.47%). Closed globe injuries were more (75%) than open globe injuries (25%). Anterior segment was involved in (94.30%) and posterior segment in (8.86%). Work-related ocular injuries formed the commonest mode of injury (41.8%) followed by road traffic accident (30.37%). Conclusion: Ocular trauma is one of the most common causes of unilateral blindness. Targeting groups most at risk with health education, providing effective eye protection and strict implementation of traffic rules may decrease the occurrence of ocular injuries.

Dexmedetomidine Moderate Sedation Versus General Anesthesia on the Diagnostic Yield of Endobronchial Ultrasound-Guided Transbronchial Needle Aspiration: A Randomized Controlled Study

Background: One of the factors that affect the diagnostic yield of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) is the level of sedation. Objectives: Therefore, we aimed to compare dexmedetomidine (DEX) as moderate sedation (MS) versus general anesthesia (GA) on the diagnostic yield of EBUS-TBNA. Methods: This randomized open-label controlled trial was carried out on 70 patients older than 18 years of age, classified as American Society of Anesthesiologists (ASA) II or III, and scheduled for EBUS-TBNA. Patients were randomly allocated into two equal groups. Group D received 1 μg/kg fentanyl 2 minutes before induction with a 1 μg/kg infusion of DEX for 10 minutes, then maintenance with 0.5 - 1 μg/kg/h aiming for a Ramsey Sedation Scale of 4 - 5 while preserving hemodynamics. Group GA received 1 μg/kg fentanyl, 2 mg/kg propofol, and 0.5 mg/kg atracurium (then 0.1 mg/kg every 20 minutes). Results: Group D had a significantly higher rate of recalling the procedure (P = 0.005) and a lower rate of shortness of breath compared to group GA (P = 0.038). Intraoperative heart rate measurements at baseline were not significantly different between groups but were significantly lower at 5 min, 10 min, 15 min, 20 min, and at the end of surgery in group D compared to group GA (P &lt; 0.05). Intraoperative mean arterial blood pressure measurements at baseline, 5 min, 10 min, 15 min, 20 min, and at the end of surgery were not significantly different between groups. Recovery time was significantly shorter in group D compared to group GA (P &lt; 0.001). Conclusions: Compared to GA, MS with DEX showed a comparable diagnostic yield with faster recovery time and better patient satisfaction, as evidenced by a willingness to repeat procedures when needed and less shortness of breath in EBUS-TBNA.

Epidural pressure measurement using a fiber-optic sensor (proof-of-principle invivo animal trial).

An increase in epidural pressure around the stenosis has been observed in patients with lumbar spinal stenosis (LSS) with positive signs of sedimentation or redundant nerve roots. Further analysis of the pressure conditions in the stenotic area would be of great interest. We hypothesized that it would be possible to determine the physiological parameters of the epidural pulse wave and its course in pathological stenosis as a basis for objective identification of LSS based on pressure using a new measuring method with continuous spatial and temporal resolution. We performed a single-case proof-of-principle invivo animal trial and used a newly developed hybrid pressure-measurement probe with a fiber-tip Fabry-Pérot interferometer and several fiber Bragg gratings (FBG). With reproducible precision, we determined the mean epidural pressure to be 7.5 mmHg and the peak-to-peak value to be 4-5 mmHg. When analyzing the pressure measured by an FBG array, both the heart and respiratory rates can be precisely determined. This study was the first to measure the pulse wave velocity of the cerebrospinal fluid pressure wave as 0.97 m/s using the newly developed pressure probe. A simulated LSS was detected in real time and located exactly. The developed fiber-optic pressure sensor probe enables a new objective measurement of epidural pressure. We confirmed our hypothesis that physiological parameters of the epidural pulse wave can be determined and that it is possible to identify an LSS.

Epidural pressure measurement using a fiber-optic sensor (proof-of-principle invivo animal trial).

An increase in epidural pressure around the stenosis has been observed in patients with lumbar spinal stenosis (LSS) with positive signs of sedimentation or redundant nerve roots. Further analysis of the pressure conditions in the stenotic area would be of great interest. We hypothesized that it would be possible to determine the physiological parameters of the epidural pulse wave and its course in pathological stenosis as a basis for objective identification of LSS based on pressure using a new measuring method with continuous spatial and temporal resolution. We performed a single-case proof-of-principle invivo animal trial and used a newly developed hybrid pressure-measurement probe with a fiber-tip Fabry-Pérot interferometer and several fiber Bragg gratings (FBG). With reproducible precision, we determined the mean epidural pressure to be 7.5 mmHg and the peak-to-peak value to be 4-5 mmHg. When analyzing the pressure measured by an FBG array, both the heart and respiratory rates can be precisely determined. This study was the first to measure the pulse wave velocity of the cerebrospinal fluid pressure wave as 0.97 m/s using the newly developed pressure probe. A simulated LSS was detected in real time and located exactly. The developed fiber-optic pressure sensor probe enables a new objective measurement of epidural pressure. We confirmed our hypothesis that physiological parameters of the epidural pulse wave can be determined and that it is possible to identify an LSS.

Dissecting the vascular-cognitive nexus: energetic vs. conventional hemodynamic parameters.

Blood pressure or flow measurements have been associated withvascular health and cognitive function. We proposed that energetic hemodynamic parameters may provide a more nuanced understanding and stronger correlation with cognitive function, in comparisons with conventional aortic and carotid pressure and flow parameters. The study comprised 1858 participants, in whom we assessed cognitive function via MoCA method, and measured central aortic and carotid pressure and flow waveforms. In addition to various pressure and flow parameters, we calculated energetic hemodynamic parameters through integration of pressure multiplying flow with respect to time. Energetic hemodynamic parameters, particularly aortic and carotid mean and pulsatile energy and pulsatility index (PI), were significantly associated with MoCA score more than any aortic and carotid pressure and flow parameters, after adjusting for age, sex, education, depression score, heart rate, BMI, HDL-cholesterol, and glucose levels. MoCA exhibited a strong positive relationship with carotid mean energy (standardized beta = 0.053, P = 0.0253) and a negative relationship with carotid energy PI (standardized beta = -0.093, P = 0.0002), exceeding the association with all traditional pressure- or flow-based parameters. Aortic pressure reflection coefficient at the aorto-carotid junction was positively correlated with mean carotid energy and negatively correlated with PI. Aortic characteristic impedance positively correlated with carotid energy PI but not mean energy. Our research indicates that energetic hemodynamic parameters, particularly carotid mean energy and carotid energy PI, have a stronger association with MoCA scores than traditional pressure- or flow-based metrics. This correlation with cognitive function is notably influenced by the properties of the aorto-carotid interface.

Dissecting the vascular-cognitive nexus: energetic vs. conventional hemodynamic parameters.

Blood pressure or flow measurements have been associated withvascular health and cognitive function. We proposed that energetic hemodynamic parameters may provide a more nuanced understanding and stronger correlation with cognitive function, in comparisons with conventional aortic and carotid pressure and flow parameters. The study comprised 1858 participants, in whom we assessed cognitive function via MoCA method, and measured central aortic and carotid pressure and flow waveforms. In addition to various pressure and flow parameters, we calculated energetic hemodynamic parameters through integration of pressure multiplying flow with respect to time. Energetic hemodynamic parameters, particularly aortic and carotid mean and pulsatile energy and pulsatility index (PI), were significantly associated with MoCA score more than any aortic and carotid pressure and flow parameters, after adjusting for age, sex, education, depression score, heart rate, BMI, HDL-cholesterol, and glucose levels. MoCA exhibited a strong positive relationship with carotid mean energy (standardized beta = 0.053, P = 0.0253) and a negative relationship with carotid energy PI (standardized beta = -0.093, P = 0.0002), exceeding the association with all traditional pressure- or flow-based parameters. Aortic pressure reflection coefficient at the aorto-carotid junction was positively correlated with mean carotid energy and negatively correlated with PI. Aortic characteristic impedance positively correlated with carotid energy PI but not mean energy. Our research indicates that energetic hemodynamic parameters, particularly carotid mean energy and carotid energy PI, have a stronger association with MoCA scores than traditional pressure- or flow-based metrics. This correlation with cognitive function is notably influenced by the properties of the aorto-carotid interface.

Concatenated Bragg grating fiber-optic sensors for simultaneous measurement of curvature, temperature, and axial pressure

Abstract. This paper presents the development and evaluation of four sensors based on multiple fiber Bragg grating (FBG) constellations embedded in a silicon dioxide single-mode fiber (SMF) for simultaneous measurement of pressure, temperature, and bending curvature. We applied dimension and material variations – including core, cladding, and coating dimensions; coating material; and the number and arrangement of the FBGs – to optimize the reflected signal response and increase information density. A bootstrap-aggregated ensemble of decision trees was used to evaluate the sensor signal. The results show that adjusting the cladding-to-coating ratio led to significant improvements in pressure and bending prediction performance. Additionally, two combined FBGs were fabricated to form a fiber Bragg grating Fabry–Pérot interferometer, which enabled the detection of curvature with a root-mean-square error (RMSE) of 0.0034 L mm−1 (R2=1), axial pressure with an RMSE of 0.0564 bar (R2=0.99), and temperature with an RMSE of 0.0265 °C (R2=1). At the time of writing, there is no commercially available instrument that can perform these measurements simultaneously.

Experimental Investigation Of The Flow-Acoustic Interaction In Human Phonation

In the human phonation process, acoustic standing waves in the vocal tract can influence the fluid flow through the glottis. To investigate the amount of two-way coupling between the flow field and the acoustics, the supraglottal flow field has been recorded via high-speed particle image velocimetry (PIV) in a synthetic larynx model for several configurations with different vocal tract lengths. Based on the obtained velocity fields, aeroacoustic source terms were computed. Furthermore, the hydrodynamic pressure in the vocal tract was recorded via wall pressure measurements. The recordings revealed that near a vocal tract resonance frequency, the focal fold oscillation frequency jumps onto the resonance. This is accompanied by a substantial relative increase in aeroacoustic sound generation efficiency. At the same time, the glottal volume flow needed for stable vocal fold oscillation decreases strongly. The pressure measurements showed that acoustic anti-resonances of the vocal tract directly dampen the harmonic content of the hydrodynamic pressure field when matching frequencies. This result shows that back-coupling of the acoustics onto the flow field does not only occur in the case where the vocal fold oscillation frequency and a resonance frequency of the vocal tract match, but also under more other conditions.