Radial Pulse Pressure Research Articles

Haemodynamics of hyperthyroidism: increased cardiac work and findings related to vasodilatation.

Hyperthyroidism increases cardiovascular morbidity and mortality, but the underlying mechanisms are not fully understood. In this study we compared non-invasive haemodynamics between 20 hyperthyroid patients and 60 euthyroid subjects. The measurements were performed median 6 days after the initiation of antithyroid medication when the patients were still hyperthyroid. Three controls matched for age, sex, body mass index, and smoking status were selected for each patient. Recordings were performed during rest and passive head-up tilt using whole-body impedance cardiography, radial pulse wave analysis, and finger blood pressure measurements. Systolic and diastolic blood pressures in the aorta and radial artery were similar in hyperthyroid and euthyroid subjects, while finger blood pressure was 16/12 mmHg lower in hyperthyroidism (p<0.001). Pulse wave velocity and aortic pulse pressure were similar, but radial pulse pressure was ~5 mmHg higher in hyperthyroidism (p=0.040) due to augmented amplification (p=0.045). Systemic vascular resistance was reduced (-18%), whereas heart rate (+19 beats/min), cardiac index (+28%), and left cardiac work (+31%) were increased in hyperthyroidism (p<0.001). Subendocardial viability ratio, reflecting the balance between coronary perfusion and pressure load, was reduced by 19% in hyperthyroidism (p<0.001). Compared with euthyroid subjects, hyperthyroid patients presented with reductions in systolic and diastolic finger blood pressures (p<0.001), and higher increase in heart rate (p=0.014) during upright posture. Hyperthyroid patients exhibited hyperdynamic circulation, reduced vascular resistance, reduced peripheral but not central blood pressure, and higher pulse pressure amplification. Furthermore, left cardiac workload was increased in parallel with unfavourable changes in coronary perfusion conditions.

Takayasu’s arteritis during pregnancy: A case report

Takayasu’s arteritis (TA) is also known as aorto arteritis having an incidence is 13/per million population. Here, we report the case of a 30-year-old woman gravida 2, para 1, who was admitted for safe delivery at 38 weeks of pregnancy. Clinical examination revealed an absence of radial pulse and blood pressure (BP) in both upper limbs and lower limbs BP recording showed 150/90 mm Hg with a pulse rate of 112/min. She was a known case of TA diagnosed during her first pregnancy. An elective cesarean section was done and a healthy male baby weighing 3.2 kg was delivered. The postnatal period was uneventful. She was discharged on the 8th day. A magnetic resonance imaging (MRI) angiogram was done before the second pregnancy. There was complete occlusion of the left common carotid artery from the origin with occlusion of the left internal carotid artery and there was collateral refilling of the left anterior cerebral artery and middle cerebral artery from the posterior communicating artery. The left vertebral artery showed circumferential wall thickening with hypointense flap within.

Development of a Simulator Capable of Generating Age-Specific Pulse Pressure Waveforms for Medical Palpation Training

With the emergence of the metaverse and other human–computer interaction technologies, promising applications such as medical palpation training are growing for training and education purposes. Thus, the overarching goal of this study is to develop a portable and simple pulse pressure simulator that can reproduce age-specific pulse pressure waveforms for medical palpation training. For training applications, the simulator is required to produce accurate radial pulse waveforms consistently and repeatedly. To this end, exploiting the cam-based pneumatic pulse generation mechanism, this study intends to develop a cylindrical (or 3D) cam whose continually varying surface contains a wide range of age-related pulse pressure profiles. To evaluate the performance of the simulator, the reproduced pulse waveforms were compared with approximate radial pulse pressure waveforms based on in vivo data in terms of the augmentation index (AI) and L2 error. The results show that the errors were less than 10% for all ages, indicating that the proposed pulse simulator can reproduce the age-specific pulse waveforms equivalent to human radial pulse waveforms. The findings in this study suggest that the pulse simulator would be an excellent system for RAPP palpation training as it can reproduce a desired pulse accurately and consistently.

Femoral Pulse Pressure Variation Is Not Interchangeable with Radial Pulse Pressure Variation during Living Donor Liver Transplantation.

The radial artery is commonly used as the site measuring pulse pressure variation (PPV) during surgery. Accurate measurement of circulating blood volume and timely interventions to maintain optimal circulating blood volume is important to deliver sufficient oxygen to tissues and organs. It has not rather than never studied in patients undergoing liver transplantation whether PPV measured at peripheral sites, such as the radial artery, do represent central PPV for evaluating blood volume. In this retrospective study, 51 liver transplant recipients were enrolled. The two PPVs had been automatically recorded every minute in electrical medical records. A total 1878 pairs of the two PPVs were collected. The interchangeability of PPV measured at the radial and the femoral artery was analyzed by using the Bland–Altman plot, four-quadrant plot, Cohen’s kappa (k), and receiver operating curve. The bias and limits of agreement of the two PPVs were −1.3% and −8.8% to 6.2%, respectively. The percentage error was 75%. The concordance rate was 65%. The Kappa of PPV-radial determining whether PPV-femoral was >13% or ≤13% was 0.64. We found that PPV-radial is not interchangeable with PPV-femoral during liver transplantation. Additionally, PPV-radial failed to reliably track changes of PPV-femoral. Lastly, the clinical decision regarding blood volume status (depletion or not) is significantly different between the two PPVs. Therefore, PPV-femoral may help maintain blood volume circulating to major organs including the newly transplanted liver graft for liver transplant recipients.

Feasibility of waveform separation of central aortic pressure pulse based on lognormal flow wave approximation

Wave reflections affect the aortic pressure and flow waves and may yield effective indices for monitoring cardiovascular health and disease. More accurate measures of wave reflection are obtainable after separation of aortic pressure waveform into its forward and backwards components. This paper presents a novel method for waveform separation of aortic pressure using a single pressure pulse measurement together with a lognormal flow wave approximation. The separated forward and backward waves were used to calculate the wave reflection parameters including reflection amplitude (RM) and reflection index (RI), and derive the aortic pulse transit time (PTT). The feasibility of the proposed method was verified using the central aortic pressure estimated from a measured radial pressure pulse by an aortic pulse analyzer and aortic flow waveform (39 data sets). Wave separation analysis (WSA) was assessed using the pressure and approximated flow waveforms based on two methods respectively, the proposed lognormal flow wave and the existing triangular flow wave. The results were compared with that of the measured flow wave. In time domain, for RM, RI, and PTT, the relations between the values calculated from the estimated flow and that from the measured flows can be characterized accurately by the linear regression models with the following coefficients of determination: R2 = 0.87 (RM), 0.86 (RI), 0.79 (PTT) using the lognormal flow; R2 = 0.84 (RM), 0.83 (RI), 0.77 (PTT) using the triangular flow. Agreement between reference and approximated values was increased when the approximated flow waveform was obtained using lognormal approximation rather than triangular estimation. The lognormal flow wave, a more physiological waveform, for approximating the flow improved the results of WSA in both time and frequency domains.

“One for two” strategy of fully integrated textile based supercapacitor powering an ultra-sensitive pressure sensor for wearable applications

Textile-based energy storage devices help realize the full potential of flexible electronics as they combine the functionality of wearable devices with the inherent high-power density and fast charging/discharging capability of supercapacitors. In this work, Nickel di-selenide (NiSe2) is grown on carbon cloth (CC) via a facile one-pot hydrothermal technique and is used for supercapacitor and pressure sensor to demonstrate a textile-based fully integrated system. In a three-electrode configuration, the NiSe2 electrode produces a half-cell specific capacitance of 980 Fg−1 at 1 Ag−1, indicating its high-rate capability. Further, the NiSe2 electrode is combined with activated carbon (AC) electrodes generated from biomass to construct an asymmetric supercapacitor device (ASC) with a 1.6 V of output voltage. The ASC device delivers maximum specific energy of 50 Whkg−1 at a current density of 1 Ag−1 and a maximum specific power of 900 Wkg−1 at 10 Ag−1. An ultra-sensitive pressure sensor is fabricated by sandwiching the NiSe2 grown carbon cloth between thin layers of PDMS, which exhibits a sensitivity of 0.91 kPa−1 in the wide dynamic pressure range of 1– 80 kPa−1. An exceptional mechanical stability is obtained for an unloading/loading of 1 kPa of pressure for 5000 cycles. Further, it is powered using the NiSe2/CC || AC/CC AFSC for steady and reliable detection of radial pulse pressure on the human wrist in real-time. This work paves a new path in exploring the potential of textiles when combined with nanomaterials to develop low-cost, self-powered healthcare systems for real-time monitoring of health parameters.

A Transfer Function Model Development for Reconstructing Radial Pulse Pressure Waveforms Using Non-Invasively Measured Pulses by a Robotic Tonometry System.

The primary goal of this study is to develop a mathematical model that can establish a transfer function relationship between the “external” pulse pressures measured by a tonometer and the “internal” pulse pressure in the artery. The purpose of the model is to accurately estimate and rebuild the internal pulse pressure waveforms using arterial tonometry measurements. To develop and validate a model without human subjects and operators for consistency, this study employs a radial pulse generation system, a robotic tonometry system, and a write model with an artificial skin and vessel. A transfer function model is developed using the results of the pulse testing and the mechanical characterization testing of the skin and vessel. To evaluate the model, the pulse waveforms are first reconstructed for various reference pulses using the model with tonometry data. They are then compared with pulse waveforms acquired by internal measurement (by the built-in pressure sensor in the vessel) the external measurement (the on-skin measurement by the robotic tonometry system). The results show that the model-produced pulse waveforms coinciding well with the internal pulse waveforms with small relative errors, indicating the effectiveness of the model in reproducing the actual pulse pressures inside the vessel.

Advancing High-Resolution Imaging of Scalp EEG and Mobile Brain/Body Imaging

Radial augmentation index (rAI), a marker of aortic wave reflection, is usually lower in patients with diabetes (DM) than in non-DM subjects, even though atherosclerotic change is advanced in DM.We sought to explore why rAI in DM is lower than in non-DM.We performed radial applanation tonometry in 1787 subjects who had at least one cardiovascular risk factor. The rAI was defined as [late systolic shoulder pressure amplitude (PP2)]/[radial pulse pressure (rPP)]. The late systolic shoulder blood pressure (SBP2) and PP2 of a radial pressure wave were used as estimates of the central SBP and PP (cPP), respectively.The age (65.8 ± 9.8 vs. 65.8 ± 12.1 yrs) and mean brachial SBP (141 ± 16 vs. 141 ± 17 mmHg) were similar between the DM and non-DM groups. The rAI was significantly lower in the DM group (83.3 ± 14.1 vs. 87.3 ± 15.7%, p < 0.001), but clinic PP (62 ± 14 vs. 59 ± 14 mmHg, p < 0.001) and cPP (51 ± 15 vs. 49 ± 15 mmHg, p = 0.019) were significantly greater in the DM group than in the non-DM group. In multivariable analyses adjusting for covariates, the significant determinants of rAI were the estimated glomerular filtration rate (eGFR) (β = 0.17, p < 0.001) in the DM group, and the log-transformed homeostatic model assessment of insulin resistance (HOMA-IR) (β = −0.15, p < 0.001) in the non-DM group. The same trends were also seen for central SBP and cPP.The lower rAI in DM associated with higher cPP compared to non-DM suggests proximal conduit–predominant arterial stiffening causing reduced reflection coefficients at systemic reflection sites. As renal function decreases, a cPP increase may overcome the increase of augmentation pressure in the DM group.

Colectomy influences the radial pulse parameters of traditional Chinese medicine pulse diagnosis in patients with colorectal cancer

IntroductionIn Traditional Chinese Medicine (TCM), manual palpation of the radial pressure pulse (RPP) has remained a traditional method of clinical diagnoses for centuries. Arterial mechanics have been studied by various researchers. Time-domain and frequency-domain analyses of the RPP has typically provided a quantitative and non-biased assessment that gives complex physiological and pathological information. To date, no preceding research has clarified the relationship of the radial pulse and the large intestine in TCM theory. In this pre-post intervention study, we compared the RPP parameters of patients with colorectal cancer before and after colectomy. MethodsThirty patients aged between 18 and 80 years old from the Department of Colorectal Surgery in Taichung Tzu Chi Hospital, Taiwan were enrolled into this study based on predefined inclusion and exclusion criteria before the colectomy. The assessment of RPP was performed before the colectomy and within 24 h after the colectomy. The mean value of the spectral energy (SE0―10 Hz, SE10―50 Hz, and SE13―50 Hz) and the radial augmentation index (AI) were obtained. ResultsWe observed that the SE10―50 Hz and SE13―50 Hz of the right Chy was significantly increased after the colectomy while the SE13―50 Hz of the right Chun was significantly decreased after the colectomy procedures. The radial AI of the right Chy was significantly reduced after the colectomy compared to the remaining pulse positions. ConclusionsTo our best knowledge, this preliminary study is the first attempt to investigate the influence of colectomy on the radial pulse parameters in patients with colorectal cancer. The major findings from this study include a significant reduction of the radial AI at the right Chy pulse, and a significant difference in the SE at the right Chy and Chun pulses after colectomy. It is also the first study using modern scientific tools to validate the TCM theory that the right Chy pulse corresponds to the changes in the large intestine through surgical removal of the visceral organs.

Associations of Intraoperative Radial Arterial Systolic, Diastolic, Mean, and Pulse Pressures with Myocardial and Acute Kidney Injury after Noncardiac Surgery: A Retrospective Cohort Analysis.

Arterial pressure is a complex signal that can be characterized by systolic, mean, and diastolic components, along with pulse pressure (difference between systolic and diastolic pressures). The authors separately evaluated the strength of associations among intraoperative pressure components with myocardial and kidney injury after noncardiac surgery. The authors included 23,140 noncardiac surgery patients at Cleveland Clinic who had blood pressure recorded at 1-min intervals from radial arterial catheters. The authors used univariable smoothing and multivariable logistic regression to estimate probabilities of each outcome as function of patients' lowest pressure for a cumulative 5 min for each component, comparing discriminative ability using C-statistics. The authors further assessed the association between outcomes and both area and minutes under derived thresholds corresponding to the beginning of increased risk for the average patient. Out of 23,140 patients analyzed, myocardial injury occurred in 6.1% and acute kidney injury in 8.2%. Based on the lowest patient blood pressure experienced for greater than or equal to 5 min, estimated thresholds below which the odds of myocardial or kidney injury progressively increased (slope P < 0.001) were 90 mmHg for systolic, 65 mmHg for mean, 50 mmHg for diastolic, and 35 mmHg for pulse pressure. Weak discriminative ability was noted between the pressure components, with univariable C-statistics ranging from 0.55 to 0.59. Area under the curve in the highest (deepest) quartile of exposure below the respective thresholds had significantly higher odds of myocardial injury after noncardiac surgery and acute kidney injury compared to no exposure for systolic, mean, and pulse pressure (all P < 0.001), but not diastolic, after adjusting for confounding. Systolic, mean, and pulse pressure hypotension were comparable in their strength of association with myocardial and renal injury. In contrast, the relationship with diastolic pressure was poor. Baseline factors were much more strongly associated with myocardial and renal injury than intraoperative blood pressure, but pressure differs in being modifiable.

Abstract 445: Monitoring the Hemodynamic Status During Three Trimesters of Pregnancy and Non-pregnancy Periods

Pregnancy is an important stage in women and is associated with delicate cardiovascular adaptation from non-pregnancy to pregnancy. Maternal hemodynamic changes are made to provide sufficient nutrients and oxygen to support the normal growth of the developing fetus. This study was designed to assess maternal hemodynamic status during three trimesters of pregnancy and non-pregnancy periods. Total 326 women (84 pregnant women and 242 age-matched non-pregnant women of childbearing age) between the ages of 20 and 44 participated in this non-invasive observational study. In this cross-sectional study, enrolled participants underwent blood pressure and radial pressure pulse measurements. In order to compare the hemodynamic status of different subjects, we recorded the systolic and diastolic blood pressure and calculated the first five harmonic amplitudes(C1~C5) and phases(P1~P5) of radial pulse wave using Fourier transform method. Compared with non-pregnant women, the maternal systolic and diastolic blood pressures were lower, and heart rate, C2, C4, and P1 were higher in pregnant women (Table 1). Those hemodynamic changes may be due to decreased arterial stiffness and peripheral arterial vasodilatation in pregnancy. In summary, a series of changes in maternal hemodynamic status can be observed during the trimesters of pregnancy, including lowering blood pressure and increasing harmonics of radial pulse. This study demonstrates the feasibility of non-invasive monitoring of the hemodynamic status of pregnant women, which could be used for early detection of pregnancy disorder.

An investigation into the effects of acupuncture on radial pressure pulse waves in patients with low back pain: A protocol for a quasi-experimental study

IntroductionThe characteristics of radial pressure pulse waves (RPPW) provide an essential diagnostic technique in Traditional Chinese Medicine (TCM). The purpose of this research is to develop a study protocol that integrates the concept of TCM and traditional acupuncture treatment with modern scientific tools utilizing a quasi-experimental design. We will investigate the effects of acupuncture on the RPPW in study participants with low back pain (LBP) using modern tools, including the pulse sphygmograph, the fingertip-to-floor test, the Faces Pain Scale-Revised, the Oswestry Disability Index, the Health Status Questionnaire, and the Constitution in Chinese Medicine Questionnaire. MethodsWe will attempt to recruit 80 eligible subjects with LBP based on our predefined inclusion and exclusion criteria. Acupuncture intervention will be performed bilaterally on Shenshu (BL23), Dachangshu (BL25) and Weizhong (BL40) for 20 min. Objective and subjective baseline assessments and outcome evaluations will be performed at a specific time before and after the intervention. This paper describes the methods of our original research approved by the China Medical University Hospital's Research Ethics Committee. Recruitment is in progress and data collection will continue until March 2019. ConclusionsTo our knowledge, this preliminary study is the first attempt to investigate the effects of acupuncture on the RPPW in LBP subjects using a pulse sphygmograph and other modern tools. The findings will also investigate the effectiveness of the selected acupuncture point combinations for LBP. We hope this preliminary study will provide a basic foundation for a large-scale research study that involves randomisation in the future.

Effect of Black Tea and Green Tea on the Radial Pulse Spectrum in Healthy Humans.

The consumption of black tea and green tea has been shown to be beneficial for cardiovascular health. Because the chemical composition of the two teas varies widely, the purpose of the study was to investigate whether the consumption of green tea and black tea had different effects on the arterial system. Thirty-three healthy subjects received a single dose of green tea (dose = 0.05 g/kg) and black tea (dose = 0.05 g/kg) in different weeks. Radial blood pressure and radial pulse pressure were measured before and after drinking tea. The harmonic analysis was performed on radial pressure waves, and harmonics (Cns) were recorded. The results showed that both black tea and green tea consumption significantly increased the C1, C2, C6, C7, C8, C9, and C10 of the radial pressure wave. Furthermore, the results confirmed that the consumption effect of green tea on C6-C10 increase is greater than that of black tea. This report also found a subtle difference that consumption of green tea increased C4, whereas consumption of black tea increased C3. We concluded that black tea and green tea have similar patterns in higher harmonics, but with varying degrees.

Calculation of central blood pressure by analyzing the contour of the photoplethysmographic pulse measured at the finger with the pOpmètre® device

Analysis of the contour of the peripheral pulse to assess arterial properties was first described in the nineteenth century. The reference technique to estimate central blood pressure (CBP), non-invasively, is by analyzing the radial pressure pulse acquired using a tonometer and then to establish a transfer function relating the radial pressure to the CBP. An alternative technique utilizes a volume pulse. This may conveniently be acquired optically from a finger. This technique deserves further consideration because of its simplicity and ease of use. The objective is to establish a transfer function estimating the central blood pressure (CBP), calibrated with a brachial pressure cuff and using the parameters obtained with the contour analysis of the photoplethysmographic pulse measured at the finger with the pOpmètre ® system. We positioned the photodiode sensor on the finger, insuring that the sensor's lens is in contact with the finger. Brachial blood pressure measurements was performed with a standard cuff. The central blood pressure values measured with Sphygmocor used as the reference values. Multiple regression analysis was done to establish the transfer functions. Sixty-nine subjects were included: 24 healthy subjects and 45 patients with essential hypertension aged 33 ± 8 years and 59 ± 17 years respectively. The correlation between the estimated central systolic pressure (CSP) and the reference one, was good and significant ( r 2 = 0.91; P < 0.0001). A better correlation was found in terms of central diastolic pressure (CDP) ( r 2 = 0.92; P < 0.0001). The Bland and Altman analysis, mean difference was 4 mmHg P < 0.0001 (CSP) versus 3 mmHg P < 0.0001 (CDP), the standard deviation of the difference was 5 mmHg (CSP) versus 4 mmHg (CDP), classifying the estimation as good agreement. The estimation of the central blood pressure with the finger pulse qualifies as good agreement with the reference technique for the central systolic and diastolic pressure estimation.

Comparison between radial artery tonometry pulse analyzer and pulsed-Doppler echocardiography derived hemodynamic parameters in cardiac surgery patients: a pilot study.

BackgroundBedside non-invasive techniques, such as radial artery tonometry, to estimate hemodynamic parameters have gained increased relevance as an attractive alternative and efficient method to measure hemodynamics in outpatient departments. For our pilot study, we sought to compare cardiac output (CO), and stroke volume (SV) estimated from a radial artery tonometry blood pressure pulse analyzer (BPPA) (DMP-Life, DAEYOMEDI Co., Gyeonggi-do, South Korea) to pulsed-wave Doppler (PWD) echocardiography derived parameters.MethodsFrom January 2015 to December 2016, all patients scheduled for coronary artery bypass (CABG) surgery at our department were screened. Exclusion criteria were, inter alia, moderate to severe aortic- or Mitral valve disease and peripheral arterial disease (PAD) > stage II. One hundred and seven patients were included (mean age 66.1 ± 9.9, 15 females, mean BMI 27.2 ± 4.1 kg/m2). All patients had pre-operative transthoracic echocardiography (TTE). We measured the hemodynamic parameters with the BPPA from the radial artery, randomly before or after TTE. For the comparison between the measurement methods we used the Bland-Altman test and Pearson correlation.ResultsMean TTE-CO was 5.1 ± 0.96 L/min, and the mean BPPA-CO was 5.2 ± 0.85 L/min. The Bland-Altman analysis for CO revealed a bias of −0.13 L/min and SD of 0.90 L/min with upper and lower limits of agreement of −1.91 and +1.64 L/min. The correlation of CO measurements between DMP-life and TTE was poor (r = 0.501, p < 0.0001). The mean TTE-SV was 71.3 ± 16.2 mL and the mean BPPA-SV was 73.8 ± 19.2 mL. SV measurements correlated very well between the two methods (r = 0.900, p < 0.0001). The Bland-Altman analysis for SV revealed a bias of −2.54 mL and SD of ±8.42 mL and upper and lower limits of agreement of −19.05 and +13.96 mL, respectively.ConclusionOur study shows for the first time that the DMP-life tonometry device measures SV and CO with reasonable accuracy and precision of agreement compared with TTE in preoperative cardiothoracic surgery patients. Tonometry BPPA are relatively quick and simple measuring devices, which facilitate the collection of cardiac and hemodynamic information. Further studies with a larger number of patients and with repeated measurements are in progress to test the reliability and repeatability of DMP-Life system.

Improving Medical Student Confidence in Clinical Skills through a Peer-Facilitated Workshop

University of Maryland, School of Maryland’s (UMSOM) curriculum does not provide training in physical exam skills to first year medical students (MS1s). A peer assisted learning model offered a unique way to address this deficiency. We aimed to design, implement, and evaluate a clinical skills workshop facilitated by upper-level medical students (upper MSs) that could be replicated by other medical schools. Faculty provided a one-hour training session to upper MSs. These students then facilitated a two-hour workshop for MS1s providing instruction on select elements of the physical exam. We theorized that upper MSs would have increased confidence in their abilities to perform the physical exam by learning to teach these skills. Additionally, we hypothesized that MS1s would have increased confidence in their abilities to perform the same skills after participating in the peer-facilitated workshop. We tested these hypotheses using a paired pre- and post-survey model and used paired sample t test analyses to determine statistical significance. We used thematic analyses to analyze free response answers. After training, upper MSs (n = 43) reported a significant improvement (p < .01) in self-reported confidence for each item: measure radial pulse, respiratory rate, and blood pressure, and auscultate lung fields and heart valves. There was a significant improvement (p < .01) in self-reported confidence by MS1s (n = 47) for the same items after the workshop. Students reported positive feedback regarding the use of peer assisted learning. Implementing a peer-facilitated workshop led to increased self-confidence in performing clinical skills by MS1s and upper MSs with minimal faculty demand. Similar models could be feasibly implemented at other institutions.

PP.09.31] CALCULATION OF CENTRAL BLOOD PRESSURE BY ANALYZING THE CONTOUR OF THE PHOTOPLETHYSMOGRAPHIC PULSE MEASURED AT THE FINGER WITH THE POPMÈTRE® DEVICE

Objective: Analysis of the contour of the peripheral pulse to assess arterial properties was first described in the nineteenth century. The reference technique to estimate central blood pressure (CBP), non-invasively, is by analyzing the radial pressure pulse acquired using a tonometer and then to establish a transfer function relating the radial pressure to the CBP. An alternative technique utilizes a volume pulse. This may conveniently be acquired optically from a finger (digital volume pulse obtained with the photodiode of the pOpmètre® device- Axelife SAS- France). The objective is to establish a transfer function estimating the central blood pressure (CBP), calibrated with a brachial pressure cuff and using the parameters obtained with the contour analysis of the photoplethysmographic pulse measured at the finger with the pOpmètre® system. Design and method: We positioned the photodiode sensor on the finger, insuring that the sensor's lens is in contact with the pulp. Brachial blood pressure measurement was performed with a cuff adapted to the arm circumference and an oscillometric device (Omron M10 -IT). The central blood pressure values measured with Sphygmocor used as the reference values, with similar calibrating pressures. Multiple regression analysis was done to establish the transfer functions. Pearson's correlation and Bland Altman graph were performed for agreement. Results: 69 subjects were included: 24 healthy subjects and 45 patients with essential hypertension aged 33 ± 8 years and 59 ± 17 years respectively. The correlation between the estimated central systolic pressure (CSP) and the reference one, was good and significant (r2 = 0.94; p < 0.0001). A better correlation was found in terms of central diastolic pressure (CDP) (r2 = 0.95; p < 0.0001). The Bland and Altman analysis, mean difference was 4 mmHg p < 0.0001 (CSP) versus 3 mmHg p < 0.0001 (CDP), the standard deviation of the difference was 5 mmHg (CSP) versus 4 mmHg (CDP), classifying the estimation as good agreement. Conclusions: The estimation of the central blood pressure with the finger pulse qualifies as good agreement with the reference technique for the central systolic and diastolic pressure estimation.

Applanation tonometry for evaluation of the haemodynamic response to the active orthostatic test

BackgroundOur study was aimed at the assessment of the age-specific hemodynamic response to the active orthostatic test (OT). MethodsTwo groups (60-Y/O and 20-Y/O) were subjected to OT (three 5-minute periods: baseline supine, upright standing, recovery supine). Continuous electrocardiogram was recorded and heart rate variability (HRV) analysed. At the end of each period pulse wave analysis was performed (Sphygmocor, AtCor Medical). ResultsWe observed significantly higher radial and central systolic and pulse pressures in the adults at baseline. We found out reduced efficiency of the hemodynamic compensatory response to orthostasis in the 60-Y/O group: mild heart rate increase (75 ± 2 vs. 88 ± 3 beats per minute); moderate aortic systolic pressure reduction (124 ± 6 to 119 ± 5 vs. 99 ± 2 to 101 ± 3 mm Hg); considerable aortic pulse pressure decrease (47 ± 4 to 38 ± 3 vs. 27 ± 2 to 22 ± 2 mm Hg); absence of diastolic pressure elevation. The adults showed significantly higher baseline augmentation indices (AIx); the young responded to the upright position with noticeable reduction of AIx most probably resulting from the pronounced tachycardia and the consequent delayed timing of pulse wave return. HRV data showed milder sympathetic activation in the 60-Y/O individuals in response to OT as compared to the 20-Y/O. ConclusionsPulse wave analysis provided new knowledge concerning the age-related hemodynamic response pattern to active orthostasis. We believe the underlying mechanism was the ‘physiological’ arterial stiffening with aging and the ensuing reduced arterial baroreflex sensitivity. HRV data for lesser sympathetic activation in response to the orthostatic challenge in the 60-Y/O group supported this assumption.

A method for determining transverse permeability of tight reservoir cores by radial pressure pulse decay measurement

AbstractA transverse pressure pulse decay (TPPD) method is presented to measure transverse permeability of tight reservoir cores in a cell with finite volume. Given appropriate assumptions, a mathematical model based on the specially designed experiment is formulated, and its general solution is proposed. Early‐time and late‐time techniques are further presented for convenient postprocessing applications of experimental data. Meanwhile, sensitivity analysis of TPPD method is given. It is found that a good TPPD experimental principle can be obtained by adjusting test gas, experimental pressure, dimension of core sample, and volume ratio (λ). The volume ratio error (λerror) analysis reveals the following: (1) a larger λerror results in increased transverse permeability error (kerror); (2) the volume ratio (λ) is better not very close to 0.754; (3) when λ is equal to or greater than 1, the kerror resulting from λerror is monotonic decreasing as the volume ratio increases. In practice, λ is usually equal to or greater than 1 due to the very small pore volume of a tight core. But this does not mean that the volume ratio should be as large as possible. The reason for this is that a pressure transducer with higher resolution is needed to record pressure change. That means experimental apparatus is much more costly. And such a TPPD experiment requires a much longer time to attain the late‐time straight line behavior. The best choice is to find an optimal balance point among experimental cost, time, and accuracy.

Why the radial augmentation index is low in patients with diabetes: The J-HOP study

BackgroundRadial augmentation index (rAI), a marker of aortic wave reflection, is usually lower in patients with diabetes (DM) than in non-DM subjects, even though atherosclerotic change is advanced in DM. ObjectiveWe sought to explore why rAI in DM is lower than in non-DM. MethodsWe performed radial applanation tonometry in 1787 subjects who had at least one cardiovascular risk factor. The rAI was defined as [late systolic shoulder pressure amplitude (PP2)]/[radial pulse pressure (rPP)]. The late systolic shoulder blood pressure (SBP2) and PP2 of a radial pressure wave were used as estimates of the central SBP and PP (cPP), respectively. ResultsThe age (65.8 ± 9.8 vs. 65.8 ± 12.1 yrs) and mean brachial SBP (141 ± 16 vs. 141 ± 17 mmHg) were similar between the DM and non-DM groups. The rAI was significantly lower in the DM group (83.3 ± 14.1 vs. 87.3 ± 15.7%, p < 0.001), but clinic PP (62 ± 14 vs. 59 ± 14 mmHg, p < 0.001) and cPP (51 ± 15 vs. 49 ± 15 mmHg, p = 0.019) were significantly greater in the DM group than in the non-DM group. In multivariable analyses adjusting for covariates, the significant determinants of rAI were the estimated glomerular filtration rate (eGFR) (β = 0.17, p < 0.001) in the DM group, and the log-transformed homeostatic model assessment of insulin resistance (HOMA-IR) (β = −0.15, p < 0.001) in the non-DM group. The same trends were also seen for central SBP and cPP. ConclusionsThe lower rAI in DM associated with higher cPP compared to non-DM suggests proximal conduit–predominant arterial stiffening causing reduced reflection coefficients at systemic reflection sites. As renal function decreases, a cPP increase may overcome the increase of augmentation pressure in the DM group.