Radial Artery Pressure Research Articles

The Effect of K ATP Channel Blocker Glibenclamide on CGRP-Induced Headache and Hemodynamic in Healthy Volunteers.

BackgroundCalcitonin gene-related peptide (CGRP) dilates cranial arteries and triggers headache. The CGRP signaling pathway is partly dependent on activation of ATP-sensitive potassium (KATP) channels. Here, we investigated the effect of the KATP channel blocker glibenclamide on CGRP-induced headache and vascular changes in healthy volunteers.MethodsIn a randomized, double-blind, placebo-controlled, cross-over study, 20 healthy volunteers aged 18–27 years were randomly allocated to receive an intravenous infusion of 1.5 μg/min CGRP after oral pretreatment with glibenclamide (glibenclamide-CGRP day) or placebo (placebo-CGRP day). The primary endpoints were the difference in incidence of headache and the difference in area under the curve (AUC) for headache intensity scores (0–14 h) between glibenclamide and placebo. The secondary endpoints were the difference in AUC for middle cerebral artery blood flow velocity (VMCA), superficial temporal artery (STA) and radial artery (RA) diameter, facial flushing, heart rate (HR) and mean arterial blood pressure (MAP) (0–4 h) between glibenclamide and placebo.ResultsWe found no significant difference in the incidence of headache between glibenclamide-CGRP day (14/20, 70%) and placebo-CGRP day (19/20, 95%) (P = 0.06). The AUC for headache intensity, VMCA, STA, RA, facial skin blood flow, HR, and MAP did not differ between glibenclamide-CGRP day compared to placebo-CGRP day (P > 0.05).ConclusionPretreatment with a non-selective KATP channel inhibitor glibenclamide did not attenuate CGRP-induced headache and hemodynamic changes in healthy volunteers. We suggest that CGRP-induced responses could be mediated via activation of specific isoforms of sulfonylurea receptor subunits of KATP channel.

Aortic pressure waveform reconstruction using a multi-channel Newton blind system identification algorithm

BackgroundCentral aortic pressure (CAP) as the major load on the left heart is of great importance in the diagnosis of cardiovascular disease. Studies have pointed out that CAP has a higher predictive value for cardiovascular disease than peripheral artery pressure (PAP) measured by means of traditional sphygmomanometry. However, direct measurement of the CAP waveform is invasive and expensive, so there remains a need for a reliable and well validated non-invasive approach. MethodsIn this study, a multi-channel Newton (MCN) blind system identification algorithm was employed to noninvasively reconstruct the CAP waveform from two PAP waveforms. In simulation experiments, CAP waveforms were recorded in a previous study, on 25 patients and the PAP waveforms (radial and femoral artery pressure) were generated by FIR models. To analyse the noise-tolerance of the MCN method, variable amounts of noise were added to the peripheral signals, to give a range of signal-to-noise ratios. In animal experiments, central aortic, brachial and femoral pressure waveforms were simultaneously recorded from 2 Sprague-Dawley rats. The performance of the proposed MCN algorithm was compared with the previously reported cross-relation and canonical correlation analysis methods. ResultsThe results showed that the root mean square error of the measured and reconstructed CAP waveforms and less noise-sensitive using the MCN algorithm was smaller than those of the cross-relation and canonical correlation analysis approaches. ConclusionThe MCN method can be exploited to reconstruct the CAP waveform. Reliable estimation of the CAP waveform from non-invasive measurements may aid in early diagnosis of cardiovascular disease.

Lower-body dynamic exercise reduces wave reflection in healthy young adults.

What is the central question of this study? There is a paradoxical reduction in augmentation index during lower-body dynamic (LBD) exercise in the face of an increase in central pressure. To determine causality, the amplitudes of forward and backward pressure waves were assessed separately using wave separation analysis. What is the main finding and its importance? Reflection magnitude decreased during LBD exercise in healthy young adults and was attributable to an increased forward pressure wave amplitude and decreased backward pressure wave amplitude. This vasoactive response might limit the adverse effects of wave reflection during LBD exercise, optimizing ventricular-arterial interactions. Acute lower-body dynamic (LBD) exercise decreases surrogate measures of wave reflection, such as the augmentation index. However, the augmentation index is influenced by the combined effects of wave reflection timing, magnitude and other confounding factors external to wave reflection, which make it difficult to discern the origin of changes in surrogate measures. The relative contributions of forward (Pf) and backward (Pb) pressure wave amplitudes to central pressure can be determined by wave separation analysis. Reflection magnitude (RM=Pb/Pf) and the timing of apparent wave reflection return can also be determined. We tested the hypothesis that acute LBD exercise decreases RM and reflected wave transit time (RWTT). Applanation tonometry was used to record radial artery pressure waveforms in 25 adults (24 ± 4 years of age) at baseline and during light-, moderate- and vigorous-intensity exercise. Wave separation analysis was conducted offline using a personalized physiological flow wave to determine Pf, Pb, RM and RWTT. The RM decreased during all intensities of exercise compared with baseline (all P<0.001; baseline, 43 ± 5%; light, 33 ± 6%; moderate, 23 ± 7%; vigorous, 17 ± 5%). The reduction in RM was attributable to the combined effect of increased Pf and decreased Pb during exercise. The RWTT decreased during all intensities of exercise compared with baseline (all P<0.04; baseline, 156 ± 17ms; light, 144 ± 15ms; moderate, 129 ± 16ms; vigorous, 121 ± 17ms). Lastly, in a stepwise multilinear regression, Pf, but not Pb and RWTT, contributed to increased central pulse pressure during LBD exercise. These data show that wave reflection decreased and that central pulse pressure is most influenced by Pf during LBD exercise.

Arterial stiffness is not acutely modified by consumption of a caffeinated soft drink sweetened with high fructose corn syrup in young healthy adults

Purpose Excessive intake of fructose is associated with an increased risk of developing cardiovascular disease. A major source of dietary fructose is the ingestion of high fructose corn syrup (HFCS) in sugar sweetened beverages (e.g., soft drinks). High arterial stiffness is an independent risk factor for cardiovascular morbidity and mortality. Thus, it is possible that regular consumption of beverages containing HFCS acutely and/or chronically increase arterial stiffness. However, this has never been explored. This study tested the hypothesis that ingestion of a caffeinated soft drink containing HFCS acutely increases arterial stiffness. Methods Fourteen healthy adults (25 ± 3 y, 6 women) reported to the laboratory for two experimental visits and consumed either 500 mL of tap water (H2O) or 500 mL of Mountain Dew® (an HFCS containing caffeinated beverage, DEW) in their first visit and consumed the other beverage in their next experimental visit, employing a counterbalanced, crossover, randomized design. Data were collected pre-consumption, 30 min post-consumption and 120 min post-consumption. Arterial stiffness was measured as carotid-to-femoral pulse wave velocity (cfPWV) using applanation tonometry. Peripheral (brachial) blood pressure was measured via electrosphygmomanometry. Central (aortic) blood pressure was estimated from transfer function analysis of the radial artery pressure waveform. Indices of pulse wave reflection were calculated from the synthesized central pressure waveforms. Data are presented as mean ± SD. Results cfPWV did not differ pre-consumption (DEW: 5.5 ± 0.6 m/s, H2O: 5.3 ± 0.7 m/s, P=0.69). At 30 min post-consumption, cfPWV was higher in the DEW trial (5.7 ± 0.6 m/s) compared to the H2O trial (5.3 ± 0.6 m/s, P=0.01), but cfPWV was not different between DEW and H2O at 120 min post-consumption (DEW: 5.7 ± 0.6 m/s, H2O: 5.5 ±0.6 m/s, P=0.13). Notably however, changes in cfPWV from pre-consumption did not differ between DEW and H2O at 30 min post- (DEW: 0.2 ± 0.3 m/s, H2O 0.0 ± 0.3 m/s, P=0.34) or 120 min post-consumption (DEW: 0.3 ± 0.4 m/s, H2O: 0.2 ± 0.3 m/s, P=0.77). Peripheral and central systolic (P≥0.50) and diastolic (P≥0.25) pressures did not differ between the DEW and H2O trials at any time point. Thus, peripheral (at 120 min post-consumption – DEW: 94 ± 6 mmHg, H2O: 92 ± 6 mmHg, P=0.31) and central (at 120 min post-consumption – DEW: 89 ± 7 mmHg, H2O: 85 ± 7 mmHg, P=0.13) mean arterial pressure also did not differ between trials. Moreover, aortic augmentation pressure, augmentation index, augmentation index corrected to a heart rate of 75 bpm, and reflection magnitude did not differ between the DEW and H2O trials at pre- (P≥0.22), 30 min post- (P≥0.55) or 120 min post-consumption (P>0.18). Conclusion Compared to drinking an equivalent volume of water, consumption of 500 mL of a commercially available caffeinated soft drink containing HFCS has little acute effect on indices of arterial stiffness or central blood pressure. The effect of chronic consumption of soft drinks containing HFCS on arterial stiffness and blood pressure regulation remain largely unknown.

Near-Infrared Spectroscopy Assessment of Tissue Oxygenation During Selective Cerebral Perfusion for Neonatal Aortic Arch Reconstruction.

Objective: Optimal selective cerebral perfusion (SCP) management for neonatal aortic arch surgery has not been extensively studied. We induced mild hypothermia during SCP and used the tissue oxygenation monitor to ensure adequate perfusion during the cardiopulmonary bypass (CPB).Methods: Eight cases were recruited from September 2018 to April 2020. SCP was maintained at 30°C, and CPB was adjusted to achieve a mean right radial artery pressure of 30 mmHg. The near-infrared tissue saturation (NIRS) monitor was applied to assess the right and left brain, flank, and lower extremity during the surgery.Results: During surgery, the mean age was 4.75 days, the mean body weight was 2.92 kg, the CPB duration was 86.5 ±18.7 min, the aortic cross-clamp time was 46.1 ± 12.7 min, and the SCP duration was 14.6±3.4 min. The brain NIRS before, during, and after SCP was 64.2, 67.2, and 71.5 on the left side and 67.9, 66.2, and 70.1 on the right side (p = NS), respectively. However, renal and lower extremity tissue oxygenation, respectively decreased from 61.6 and 62.4 before SCP to 37.7 and 39.9 after SCP (p < 0.05) and then increased to 70.1 and 90.4 after full body flow resumed. No stroke was reported postoperatively.Conclusion: SCP under mild hypothermia can aid in efficient maintenance of brain perfusion during neonatal arch reconstruction. The clinical outcome of this strategy was favorable for up to 20 min, but the safety duration of lower body ischemia warrants further analysis.

Correlation between radial and femoral arterial blood pressure during reperfusion in living donor liver transplantation.

Background and Aims:Accurate blood pressure measurements are the mainstay for the efficient management of abrupt cardiovascular changes during reperfusion in liver transplant. We sought to compare the femoral and radial pressures during reperfusion and at T1:baseline, T2: 1 h in dissection: T3:portosystemic shunt, T4:reperfusion, T5: at bile duct anastomosis.Methods:A retrospective study was performed amongst 102 adult patients who underwent R lobe living donor liver transplantation. Mean arterial pressure (MAP) and systolic arterial pressure (SAP) at 10 s intervals at reperfusion and at five fixed time points were compared by intraclass correlation coefficient (ICC) and limits of agreement by Bland–Altman statistics.Results:MAP by both routes had a good correlation at all time points during reperfusion (overall ICC: 0.946 [0.938, 0.949]) in comparison with SAP (overall ICC: 0.650 [0.6128, 0.684]). At the lowest reperfusion pressure (reperfusion point), MAP showed high levels of agreements (ICC: 0.833 [0.761, 0.885]), whereas SAP showed only a poor level of agreement (ICC 0.343 [0.153, 0.508]). The Bland–Altman analysis for MAP showed a bias of 7.18 (5.94) mmHg and limits of agreement of − 4.5 mmHg to + 18.8 mmHg and for SAP a bias of 25.2 (22.04) mmHg and limits of agreement of − 18.0 mmHg to + 68.4 mmHg at the reperfusion point. The incidence of post-reperfusion syndrome (PRS) was 52.94% by femoral and 57.84% by radial routes.Conclusions:Radial MAP correlated well with femoral MAP during reperfusion and at predefined time points and can be used interchangeably for intraoperative monitoring. A high incidence of PRS was noted by our technique of measurement.

EVOLUTION OF TRANSIT TIME BETWEEN THE SYSTOLIC AND DIASTOLIC PRESSURE PEAKS OF THE RADIAL PULSE WAVEFORM AFTER KIDNEY TRANSPLANTATION

Objective: The transit time between peak systolic and peak diastolic digital volume pulse had been proposed as a measure of arterial stiffness. Indeed, the height of an individual divided by such transit time can be used to estimate a pulse wave velocity. In a cohort of patients with end-stage kidney disease, we aim to examine whether the reduction of aortic stiffness that occurs after kidney transplantation (KTx), translates into improvement of radial artery systolic-diastolic pulse transit time. Design and method: Before and three months after KTx, we recorded radial pressure waveforms using applanation tonometry in 62 patients. We used a two gaussian method to break down the radial pressure waveforms to extract transit time. Radial waveforms were recorded over a 10 seconds period and ensemble-averaged (using in house-MATLAB program) to obtain a single waveform and then modelled using two Gaussian functions. Transit time (dT) was determined as the difference between the first systolic peak (T1) and the early diastolic peak (T2). Generalized transfer function was used to estimate central blood pressures. Carotid-radial and carotid-femoral pulse wave velocities (cr-PWV, cf-PWV) were also measured. Results: 62 patients (66% male, mean age: 48 ± 14 years, mean eGFR: 66 ± 17 ml/min/1.73m2) were assessed. After KTx, there was a significant reduction in cr-PWV (9.49 ± 1.50 to 8.94 ± 1.34, p = 0.001) and cf-PWV (11.56 ± 2.65 to 10.19 ± 1.72, p &lt; 0.001), as well as in central and peripheral blood pressure (p &lt; 0.001). While T1 significantly declined (0.184 [0.172–0.199] to 0.179 [0.164–0.194]s, p = 0.008), there were no significant changes in transit time (0.139 [0.119–0.165] to 0.134 [0.118–0.178]s, p = 0.390) nor in T2 (0.325 [0.293–0.361] to 0.319 [0.283–0.357]s, p = 0.119). Conclusions: Contrary to our expectation, three months after KTx, we did not observe a significant change in transit time. Our results suggest that transit time between the systolic and diastolic pressure peaks of the radial pulse waveform may not be used as a marker of arterial stiffness. We propose that the radial artery pressure wave integrates information from both upstream and downstream vascular beds and so the transit time cannot be used as a reliable surrogate for arterial stiffness.

EFFECTS OF SMOKING ON CENTRAL BLOOD PRESSURE

Abstract Objective: Smoking is known to induce systemic vascular damage, leading to cardiovascular diseases. Recent studies demonstrated that central blood pressure has a greater impact on cardiovascular events than brachial blood pressure. We investigated effects of habitual smoking on central systolic blood pressure (CSBP) in the general population. Design and method: A total of 5630 subjects (male = 2622, 51.7 ± 12.0 year-old at baseline), who visited our hospital for a physical check-up at least twice during the last 10 years and underwent CSBP measurement at each visit, were enrolled, and effects of smoking on the average and yearly changes of CSBP (median follow-up 5 years) were analyzed. Brachial blood pressure (oscillometer) and radial artery pressure waveforms (tonometer) were recorded using an automated device, and the pressure corresponding to the second systolic peak of radial pressure waveforms was taken as CSBP (HEM-9000AI, Omron Healthcare, Kyoto). Hypertension was defined as brachial BP &gt; = 140/90mmHg or the use of antihypertensive medications. A yearly change in CSBP was calculated in each subject by linear regression analysis using longitudinal data. Results: The average CSBP during the follow-up was higher in habitual smokers than in non-smokers when analyzed in normotensive (n = 4634, 109.1 ± 11.7 vs. 107.6 ± 12.8 mmHg, p &lt; 0.001) and non-treated hypertensive subjects (n = 91, 150.7 ± 14.8 vs. 142.8 ± 16.7 mmHg, p &lt; 0.05), whereas in hypertensive subjects under medication the average CSBP was lower in smokers than in non-smokers (n = 905, 124.6 ± 12.4 vs. 127.8 ± 13.6 mmHg, p &lt; 0.01). Although smoking status did not affect yearly changes of CSBP in both normotensive (habitual smokers vs. non-smokers; 1.38 ± 6.00 vs. 1.44 ± 6.04 mmHg/year) and treated hypertensive subjects (-0.16 ± 7.08 vs. -0.66 ± 8.24 mmHg/year), the unfavorable effect of smoking on yearly increase of CSBP was found in non-treated hypertensive subjects (4.09 ± 15.1 vs. -0.53 ± 10.3 mmHg/year). Conclusions: Habitual smoking increases CSBP especially in subjects with hypertension, however, antihypertensive medications counteract the unfavorable effects of smoking on CSBP. These results imply a new pathway underlying the development of cardiovascular diseases in smokers. Unfavorable changes in the cardiovascular system caused by smoking may quite slowly progress that short period of observation in the present study could not have detected enhanced yearly increases of CSBP by smoking.

Intra-arterial versus oscillometric blood pressure measurements in women with severe peripartum hypertension undergoing urgent treatment with nicardipine: An observational study.

The aim of this study was to compare radial arterial catheter-derived pressure with oscillometric blood pressure in women with severe peripartum hypertension undergoing urgent treatment with intravenous nicardipine at a maternal intensive care unit. We obtained patients' paired values of systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP). All of the measurements were divided into four groups based on the levels of SBP and MAP measured using the oscillometric method. We assessed agreements of the paired values using the Bland-Altman method. The clinical relevance of differences between the two methods was assessed by error grid analysis. A total of 337 paired SBP and DBP values and 305 paired MAP values were obtained for 89 patients. The values of intra-arterial SBP were higher than those of oscillometric SBP. The values of intra-arterial MAP were higher than those of oscillometric MAP except for the women with MAP≥125mm Hg. Bland - Altman analysis showed acceptable agreement for DBP and MAP measured by intra-arterial method and oscillometric method. Error grid analysis showed the proportions of measurements in risk zones A to E were 83.22%, 16.46%, 0.32%, 0%, and 0% for SBP, and 97.81%, 2.19%, 0%, 0%, and 0% for MAP, respectively. Intra-arterial MAP can be used reliably to monitor the effect of intravenous nicardipine for treating severe hypertension. Intra-arterial SBP may trigger moderate-risk treatment decisions in the women with oscillometric SBP≤160mm Hg.

Estimation of cardiac output variations induced by hemodynamic interventions using multi-beat analysis of arterial waveform: a comparative off-line study with transesophageal Doppler method during non-cardiac surgery

Multi-beat analysis (MBA) of the radial arterial pressure (AP) waveform is a new method that may improve cardiac output (CO) estimation via modelling of the confounding arterial wave reflection. We evaluated the precision and accuracy using the trending ability of the MBA method to estimate absolute CO and variations (ΔCO) during hemodynamic challenges. We reviewed the hemodynamic challenges (fluid challenge or vasopressors) performed when intra-operative hypotension occurred during non-cardiac surgery. The CO was calculated offline using transesophageal Doppler (TED) waveform (COTED) or via application of the MBA algorithm onto the AP waveform (COMBA) before and after hemodynamic challenges. We evaluated the precision and the accuracy according to the Bland & Altman method. We also assessed the trending ability of the MBA by evaluating the percentage of concordance with 15% exclusion zone between ΔCOMBA and ΔCOTED. A non-inferiority margin was set at 87.5%. Among the 58 patients included, 23 (40%) received at least 1 fluid challenge, and 46 (81%) received at least 1 bolus of vasopressors. Before treatment, the COTED was 5.3 (IQR [4.1–8.1]) l min−1, and the COMBA was 4.1 (IQR [3–5.4]) l min−1. The agreement between COTED and COMBA was poor with a 70% percentage error. The bias and lower and upper limits of agreement between COTED and COMBA were 0.9 (CI95 = 0.82 to 1.07) l min−1, −2.8 (CI95 = −2.71 to−2.96) l min−1 and 4.7 (CI95 = 4.61 to 4.86) l min−1, respectively. After hemodynamic challenge, the percentage of concordance (PC) with 15% exclusion zone for ΔCO was 93 (CI97.5 = 90 to 97)%. In this retrospective offline analysis, the accuracy, limits of agreements and percentage error between TED and MBA for the absolute estimation of CO were poor, but the MBA could adequately track induced CO variations measured by TED. The MBA needs further evaluation in prospective studies to confirm those results in clinical practice conditions.

Fiber Bragg Grating-Based Pulse Monitoring Device for Real-Time Non-Invasive Blood Pressure Measurement—A Feasibility Study

The real-time, continuous, beat-to-beat blood pressure (BP) monitoring is vital in clinical scenarios such as operations theatres, ambulances etc. In the present study, a non-invasive BP monitoring methodology based on Fiber Bragg Grating sensors is reported. The design and development of Fiber Bragg Grating based Pulse Monitoring Device (FBGPM) is demonstrated which is capable of acquiring the radial arterial pulse pressure waveform effectively in real time. The Radial Arterial Pulse Pressure Waveform is acquired on beat to beat basis employing developed FBGPM in a clinical environment. Further, the recorded radial arterial pulse pressure waveform is processed to obtain systolic and diastolic BP by utilizing a standard non-invasive BP measurement device as a reference. The BP values obtained through FBGPM are then compared with the BP values obtained through an Intra-Arterial (IA) probe. The FBGPM is a chemically and electrically inert device which makes it an effective candidate for monitoring the real-time BP. The focus of the study is to demonstrate the feasibility of deploying developed FBGPM device in clinical environment to acquire beat-to-beat BP and subsequently compare the present device to the IA probe method of BP acquisition.

Continuous Noninvasive Arterial Pressure Monitoring for Transcatheter Aortic Valve Replacement

The objective of the present study, which was conducted in patients undergoing transcatheter aortic valve replacement, was to compare continuous noninvasive arterial pressure measured with the ClearSight device (Edwards Lifesciences, Irvine, CA) with invasive radial artery pressure used as the reference method. The authors hypothesized that the ClearSight device is an accurate, precise, safe, and efficient method for arterial blood pressure measurement comparable with an invasive radial arterial line. The study included the retrospective review of 20 consecutive patients scheduled for elective transcatheter aortic valve replacement with the SAPIEN 3 transcatheter heart valve (Edwards Lifesciences) at a single tertiary academic hospital, who underwent monitoring with both the ClearSight device and an invasive radial arterial pressure line. The patients underwent transcatheter aortic valve replacement from October to December 2019. Single tertiary academic medical center. The study comprised 20 patients, with 2,243 unique blood pressure data points. None. A statistically significant correlation between the invasive radial arterial pressure line and the ClearSight device was observed for systolic blood pressure (correlation coefficient 0.86; p < 0.001), diastolic blood pressure (correlation coefficient 0.56; p < 0.001), and mean arterial pressure (correlation coefficient 0.78; p < 0.001). Bland-Altman analysis was used to assess the agreement of systolic blood pressure, diastolic blood pressure, and mean arterial pressure between the two methods. Results for systolic blood pressure between the arterial line and ClearSight device were as follows: bias = 9.8 ± 10.1, percentage bias = 7.6%, and mean error = 15.8%. Results for diastolic blood pressure between the arterial line and ClearSight device were as follows: bias = -5.9 ± 7.8, percentage bias = 10.7%, and mean error = 28.4%. Results for mean arterial pressure between the arterial line and ClearSight device were as follows: bias = 0.3 ± 7.4, percentage bias = 0.4%, and mean error = 18.3%. The concordance rates of systolic blood pressure, diastolic blood pressure, and mean arterial pressure were 100%, 95.1%, and 98.8%, respectively. The accuracy, agreement, and precision of the ClearSight device were convincing for mean arterial pressure, systolic blood pressure, and diastolic blood pressure for patients with severe aortic stenosis undergoing elective transcatheter aortic valve replacement.

PULSE-WAVEFORM AND LASER-DOPPLER INDICES FOR IDENTIFYING COLORECTAL-CANCER PATIENTS

This study aimed to determine the effectiveness of using noninvasive arterial pulse-wave and laser-Doppler flowmetry (LDF) measurements to discriminate between colorectal-cancer (CC) patients and healthy control subjects. Radial-artery blood pressure waveform (BPW), finger photoplethysmography (PPG), and skin-surface LDF signals were measured noninvasively in 12 CC patients and 25 control subjects. Beat-to-beat, spectral, and variability analyses were applied to 20-minute-long recorded signals. Significant intergroup differences were found. In BPW, [Formula: see text]–[Formula: see text] amplitude indices were significantly larger while [Formula: see text]–[Formula: see text] phase-angle indices were significantly smaller in the CC patients than in the controls. The PPG and LDF variability indices were significantly larger and smaller, respectively, in CC patients. The relative energy contributions of the endothelial-, neural-, and myogenic-related frequency bands in LDF were significantly smaller in CC patients. The present findings indicate that pulse and LDF waveform analysis can be used to evaluate the arterial pulse-wave transmission condition, the responses of the blood-flow perfusion, and its regulatory activities in CC patients. There could be some similarities and differences in the present indices for different types of cancer. These findings could be utilized in the development of a rapid, noninvasive, and objective technique for evaluating the CC-induced blood-flow responses.

Abstract 15385: A Tapered BP Cuff More Accurately Measures Systolic Blood Pressure Than Does a Standard Rectangular BP Cuff Over a Range of Arm Circumferences

Introduction: Systolic blood pressure (BP) is an important risk factor for cardiovascular outcomes. However, non-invasive measures obtained using a standard rectangular cuff (RC) are accurate only when the width of the cuff is ~40% of the arm circumference (AC). This ideal Ratio (IR) is met for the medium standard rectangular cuff at an AC of 30 cm. Hypothesis: A tapered cuff (TC) designed to maintain the IR over a range of ACs more accurately measures systolic BP than does a standard rectangular cuff. Methods: Twenty-two measures of BP using the RC and the TC were compared in seven patients with ACs of 30 cm. In addition, twenty-seven measures of SBP using the RC and the TC were compared with radial artery pressures in 12 patients with clinically placed arterial lines and arm circumferences ranging from 24 cm to 38 cm. Results: When ACs were 30 cm, there was no significant difference between the RC and SC systolic pressures (mean ± SD difference of 1.3 mmHg ± 0.8, p=.78) and they correlated with one another, R 2 of 0.99. However, over a range of ACs, the RC systolic pressures significantly differed from the arterial pressures (mean difference ± SD of 11 ± 4 mmHg, p=.005), and did not correlate with the arterial readings (Panel A) , whereas the TC systolic pressures did not differ from the arterial pressures (mean difference ± SD of 2 ± 1.3 mmHg, p=.18) and did correlate with the arterial readings (Panel B). Conclusion: Systolic BPs obtained with a TC which maintains the IR over a continuous range of arm circumferences are more accurate than are those obtained with a RC.

Study on the hydrodynamic mechanisms of the radial arterial blood pressure variation in response to arm elevation

Objective: To analyze the mechanism of invasive blood pressure change in radial artery caused by arm elevation by observing pressure, velocity and diameter of radial artery. Methods: Twenty-six hemodynamically stable hepatobiliary surgery patients admitted to the intensive care unit from June to December 2018 after general anesthesia in Tsinghua Changgung Hospital were selected. When the arm was raised, the invasive blood pressure was recorded, and the inner diameter and blood flow velocity of the radial artery were measured by Doppler ultrasound. The data following a normal distribution were compared with paired t test. Results: After arm elevation for 30 s, systolic blood pressure of radial artery decreased and diastolic blood pressure increased significantly((107±16) mmHg vs (120±17) mmHg, (75±6) mmHg vs (71±9) mmHg, t=25.0, -12.6, both P<0.05), but there was no significant difference in mean arterial pressure ((87±10) mmHg vs (87±11) mmHg, t=1.1, P>0.05). The peak velocity, end-diastolic velocity and resistance index of the radial artery increased significantly, and the transverse and longitudinal inner diameters of the radial artery decreased significantly after the arm was elevated for 30 s (t=-63.4, -14.6, -22.5, 31.4, 25.3, all P<0.01). Conclusions: Kinetic pressure compensation and vascular resistance compensation may be the main mechanism of radial artery pressure change when the arm is elevated. Arm elevation can be used as a vascular resistance response test clinically.

Comparison of cardiac output measurements during coronary artery bypass grafting by arterial pressure waveform (flotractm/vigileo): femoral versus radial

Introduction Cardiac output (CO) monitoring is essential in the assessment of cardiac function and organ perfusion.Thus, CO monitoring is highly recommended in high-risk surgical procedures and critically ill patients1.Despite the invasiveness and associated risk of pulmonary artery catheterization (PAC) with thermodilution, it is still accepted as a gold standard method for evaluating CO1,2.Recently many less invasive or non-invasive devices became available for this purpose. One of these alternatives is FloTracTM/Vigileo system which estimates CO by analyzing the arterial waveform derived from peripheral and central arteries1,3. Since catheterization of radial artery is very common in cardiac surgery, the purpose of this study was to investigate the reliability of femoral versus radial arterial pressure for measuring CO as well as other hemodynamic parameters through FloTracTM/Vigileo system. Methods This was a prospective comparative study. In 73 patients undergoing elective coronary artery bypass grafting (CABG) surgery, we measured simultaneously CO and other hemodynamic parameters derived from both radial and femoral arteries at different important time intervals: before and after sternotomy, before starting cardiopulmonary bypass (CPB), before and after CPB weaning, before and after sternal closure and every 1 hour for 6 hours in the intensive care unit. In addition, the duration of the aortic cross-clamp, the total pump time and administration of any inotropic drugs were recorded. Results The mean CO between the two radial and femoral arteries was not significantly different at any of the time points. There were no significant differences in mean arterial pressure (MAP) in both arteries (P>0.05). The correlation coefficient of CO changes with pump time in the radial and femoral arteries was inverse and significant (P 0.05). Discussion Determination of CO by FloTracTM/Vigileo system demonstrated that the data derived from femoral artery did not differ significantly from radial artery. As a result, both sites of monitoring of arterial pressure waveform (radial and femoral) are acceptable for measuring of CO and other hemodynamic parameters during CABG.

Validation of noninvasive continuous arterial pressure measurement by ClearSight System\u2122 during induction of anesthesia for cardiovascular surgery

BackgroundSince blood pressure tends to be unstable during induction of anesthesia in patients undergoing cardiovascular surgery, an artery catheter is often inserted before induction to continuously monitor arterial pressure during induction of anesthesia. ClearSight System™ enables noninvasive continuous measurement of beat-to-beat arterial pressure via a single finger cuff without pain using photoplethysmographic technology. If ClearSight System™ can replace intra-arterial pressure measurement, blood pressure could be easily and noninvasively assessed. However, the validity of ClearSight System™ during induction of anesthesia in patients undergoing cardiovascular surgery has not been evaluated. The aim of this study was to compare blood pressure measured by ClearSight System™ with intra-arterial pressure during induction of anesthesia for cardiovascular surgery.MethodsThis study was registered retrospectively. Data during induction of anesthesia for elective cardiovascular surgery were obtained for patients in whom noninvasive arterial pressure was measured by ClearSight System™ (APcs) and invasive radial arterial pressure (APrad) was measured simultaneously. According to the widely used criteria formulated by international standards from the Association for the Advancement of Medical Instrumentation, the acceptable bias and precision for arterial pressure measurements were fixed at < 5 mmHg and 8 mmHg, respectively.ResultsData for 18 patients were analyzed. For 3068 analyzed paired measurements, values of APcs vs APrad bias (precision) were 13.2 (17.5), − 9.1 (7.3) and − 3.9 (7.8) mmHg for systolic, diastolic, and mean arterial pressures, respectively.ConclusionsMean arterial pressure measured by ClearSight System™ could be considered as an alternative for mean radial arterial pressure during induction of anesthesia for elective cardiovascular surgery.

Feasibility of Estimation of Aortic Wave Intensity Using Non-invasive Pressure Recordings in the Absence of Flow Velocity in Man.

BackgroundWave intensity analysis provides valuable information on ventriculo-arterial function, hemodynamics, and energy transfer in the arterial circulation. Widespread use of wave intensity analysis is limited by the need for concurrent measurement of pressure and flow waveforms. We describe a method that can estimate wave intensity patterns using only non-invasive pressure waveforms (pWIA).MethodsRadial artery pressure and left ventricular outflow tract (LVOT) flow velocity waveforms were recorded in 12 participants in the Southall and Brent Revisited (SABRE) study. Pressure waveforms were analyzed using custom-written software to derive the excess pressure (Pxs) which was scaled to peak LVOT velocity and used to calculate wave intensity. These data were compared with wave intensity calculated using the measured LVOT flow velocity waveform. In a separate study, repeat measures of pWIA were performed on 34 individuals who attended two clinic visits at an interval of ≈1 month to assess reproducibility and reliability of the method.ResultsPxs waveforms were similar in shape to aortic flow velocity waveforms and the time of peak Pxs and peak aortic velocity agreed closely. Wave intensity estimated using pWIA showed acceptable agreement with estimates using LVOT velocity tracings and estimates of wave intensity were similar to values reported previously in the literature. The method showed fair to good reproducibility for most parameters.ConclusionThe Pxs is a surrogate of LVOT flow velocity which, when appropriately scaled, allows estimation of aortic wave intensity with acceptable reproducibility. This may enable wider application of wave intensity analysis to large studies.

The role of the maximal first derivative of the radial pulse wave (Rad dP/dtmax) in monitoring cardiac function.

BackgroundThis study aimed to assess the clinical significance of the maximal first derivative of the radial pulse wave (Rad dP/dtmax) in monitoring cardiac function with different perioperative patients by researching the relationship between Rad dP/dtmax and cardiac output (CO).MethodsPatients with non-pump coronary artery bypass grafting (CABG) and open liver tumor resection (OLTR) were enrolled in this study (n=10). CO was measured using the thermodilution Swan-Ganz catheter method and Rad dP/dtmax was acquired by the analysis of patients’ left radial artery pressure waveform through the PowerLab data acquisition device. CO, Rad dP/dtmax, heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure, central venous pressure, mean pulmonary arterial pressure, pulmonary artery wedge pressure (PAW), and body surface area was recorded. Data were analyzed using a mixed linear model of time-dependent covariates to duplicate the data.ResultsThe bivariate correlation coefficients of Rad dP/dtmax and CO were 0.526 and 0.413. The result of the multivariate mixed linear model analysis showed that compared with other indicators, Rad dP/dtmax had the greatest standardized coefficient with CO in CABG patients. While in OLTR patients, HR, SBP, PAW, and DBP had larger standardized coefficients.ConclusionsRad dP/dtmax could be a useful indicator to reflect and predict the acute changes in cardiac function in perioperative patients, especially for patients with cardiac dysfunction or contractility abnormality.

Comparing the Accuracy of Physiologic and Triangular Pseudoflow Waveforms for Estimating Wave Reflection Indices in Adults

Central aortic pressure waveforms contain valuable prognostic information in addition to central systolic pressure. Using wave separation analysis, aortic pressure‐flow relations can be used to decompose aortic pressure waveforms into forward (Pf) and backward‐travelling (Pb) components. Pf and Pb are used to calculate reflection magnitude (RM=Pb/Pf) which is predictive of heart failure and all‐cause mortality. Aortic blood flow can be measured non‐invasively via ultrasonography or estimated using a triangular pseudoflow waveform; however, the latter can underestimate true flow and thus overestimate Pb and RM. Recently, a physiologic pseudoflow waveform has been developed that improves on the assumptions of triangulation and so may provide a more accurate estimation of wave reflection.PURPOSEThe purpose of this study was to compare estimates of Pf, Pb, and RM derived from physiologic and triangular pseudoflow waveforms relative to measured flow. We hypothesized that the physiologic waveform would provide a more accurate estimate of wave reflection indices compared to the triangular waveform.METHODSIn 75 adults (age 18–75 yrs), radial artery pressure waveforms were acquired with applanation tonometry and a generalized transfer function was used to synthesize central pressure waveforms. Aortic blood flow velocities were measured via echocardiography and estimated using physiologic (in‐house software) and triangular (SphygmoCor CvMS) pseudoflow waveforms. Pressure‐flow relations were established offline and wave separation analysis was performed. Accuracy of the physiologic and triangular‐derived estimates of Pf, Pb, and RM were assessed using 95% equivalence testing, paired t‐tests comparing the mean absolute biases, and Bland‐Altman plots.RESULTSUsing a 10% equivalence zone as the maximum acceptable difference, the physiologic and triangular pseudoflow waveforms were both comparable to the measured flow waveform in deriving Pf. However, only the physiologic waveform yielded similar estimates of Pb and RM compared to the measured waveform. Further, the physiologic waveform yielded lower mean absolute biases compared to the triangular waveform for Pf (1.7 ± 2.1 vs. 2.8 ± 2.6 mmHg, p&lt;0.001), Pb (1.0 ± 1.1 vs. 3.3 ± 2.7 mmHg, p&lt;0.001), and RM (3 ± 3 vs. 14 ± 13%, p&lt;0.001). Lastly, Bland‐Altman biases were smaller, and 95% limits of agreement were narrower, for all wave reflection indices derived from the physiologic waveform than from the triangular waveform.CONCLUSIONThese data suggest that the physiologic pseudoflow waveform provides a more accurate estimate of wave reflection indices compared to the triangular waveform, and thus may offer a superior alternative when true flow cannot be measured.