Non-invasive Arterial Pressure Measurement Research Articles

In silico data-based comparison of the accuracy and error source of various methods for noninvasively estimating central aortic blood pressure

Background and objectivesThe higher clinical significance of central aortic blood pressure (CABP) compared to peripheral blood pressures has been extensively demonstrated. Accordingly, many methods for noninvasively estimating CABP have been proposed. However, there still lacks a systematic comparison of existing methods, especially in terms of how they differ in the ability to tolerate individual differences or measurement errors. The present study was designed to address this gap. MethodsA large-scale ‘virtual subject’ dataset (n = 600) was created using a computational model of the cardiovascular system, and applied to examine several classical CABP estimation methods, including the direct method, generalized transfer function (GTF) method, n-point moving average (NPMA) method, second systolic pressure of periphery (SBP2) method, physical model-based wave analysis (MBWA) method, and suprasystolic cuff-based waveform reconstruction (SCWR) method. The errors of CABP estimation were analyzed and compared among methods with respect to the magnitude/distribution, correlations with physiological/hemodynamic factors, and sensitivities to noninvasive measurement errors. ResultsThe errors of CABP estimation exhibited evident inter-method differences in terms of the mean and standard deviation (SD). Relatively, the estimation errors of the methods adopting pre-trained algorithms (i.e., the GTF and SCWR methods) were overall smaller and less sensitive to variations in physiological/hemodynamic conditions and random errors in noninvasive measurement of brachial arterial blood pressure (used for calibrating peripheral pulse wave). The performances of all the methods worsened following the introduction of random errors to peripheral pulse wave (used for deriving CABP), as characterized by the enlarged SD and/or increased mean of the estimation errors. Notably, the GTF and SCWR methods did not exhibit a better capability of tolerating pulse wave errors in comparison with other methods. ConclusionsClassical noninvasive methods for estimating CABP were found to differ considerably in both the accuracy and error source, which provided theoretical evidence for understanding the specific advantages and disadvantages of each method. Knowledge about the method-specific error source and sensitivities of errors to different physiological/hemodynamic factors may contribute as theoretical references for interpreting clinical observations and exploring factors underlying large estimation errors, or provide guidance for optimizing existing methods or developing new methods.

Noninvasive Arterial Pressure Measurements at the Lower Leg: Evaluation of the Influence of Patient Position (Semi-Recumbent or Horizontal)—A prospective study

Noninvasive Arterial Pressure Measurements at the Lower Leg: Evaluation of the Influence of Patient Position (Semi-Recumbent or Horizontal)—A prospective study

Finger cuff versus invasive and noninvasive arterial pressure measurement in pregnant patients with obesity.

Pregnant patients with obesity may have compromised noninvasive blood pressure (NIBP) measurement. We assessed the accuracy and trending ability of the ClearSight™ finger cuff (FC) with invasive arterial monitoring (INV) and arm NIBP, in obese patients having cesarean delivery. Participants were aged ≥18 years, ≥34 weeks gestation, and body mass index (BMI) ≥ 40 kg m-2. FC, INV, and NIBP measurements were obtained across 5-min intervals. The primary outcome was agreement of FC measurements with those of the reference standard INV, using modified Bland-Altman plots. Secondary outcomes included comparisons between FC and NIBP and NIBP versus INV, with four-quadrant plots performed to report discordance rates and evaluate trending ability. Twenty-three participants had a median (IQR) BMI of 45 kg m-2 (44-48). When comparing FC and INV the mean bias (SD, 95% limits of agreement) for systolic blood pressure (SBP) was 16 mmHg (17, -17.3 to 49.3 mmHg), for diastolic blood pressure (DBP) -0.2 mmHg (10.5, -20.7 to 20.3), and for mean arterial pressure (MAP) 5.2 mmHg (11.1, -16.6 to 27.0 mmHg). Discordance occurred in 54 (26%) pairs for SBP, 41 (23%) for DBP, and 41 (21.7%) for MAP. Error grid analysis showed 92.1% of SBP readings in Zone A (no-risk zone). When comparing NIBP and INV, the mean bias (95% limits of agreement) for SBP was 13.0 mmHg (16.7, -19.7 to 29.3), for DBP 5.9 mmHg (11.9, -17.4 to 42.0), and for MAP 8.2 mmHg (11.9, -15.2 to 31.6). Discordance occurred in SBP (84 of 209, 40.2%), DBP (74 of 187, 39.6%), and MAP (63 of 191, 33.0%). The FC and NIBP techniques were not adequately in agreement with INV. Trending capability was better for FC than NIBP. Clinically important differences may occur in the setting of the perfusion-dependent fetus.

Perioperative Validation of the TensorTip™ MTX Device for Noninvasive Arterial Pressure Measurement: A Method Comparison Study.

The noninvasive TensorTip™ MTX measures blood pressure by interpreting blood diffusion color of the finger skin. In addition to blood pressure, the device is able to measure various vital signs: heart rate, oxygen saturation, stroke volume, and cardiac output. Studies about accuracy and precision thus far available have only been conducted by the manufacturer. The aim of our study was to investigate the accuracy and precision of the TensorTip MTX in comparison to invasive radial artery blood pressure values. Forty-one patients scheduled for elective surgery were enrolled in this study. Placement of the arterial catheter had to be part of the standard of care. Once hemodynamic stable conditions were achieved, blood pressure was measured. Three measurements with the TensorTip MTX were averaged and compared with one invasive blood pressure measurement using Bland-Altman plot and error grid analysis. Systolic, diastolic, and mean blood pressure had a bias of respectively 6.2, -6.9 and 4.4 mm Hg. Corresponding standard deviation were respectively 30.1, 17.0 and 22.2. Calculated percentage errors were 47.6%, 52.9% and 52.3%. Proportional bias was present in all Bland-Altman analyses. Error grid analysis showed 61.0% of systolic blood pressure measurements, and 46.3% of mean blood pressure measurements were in the clinical acceptable zone. The TensorTip MTX was not able to reliably measure blood pressure compared to blood pressure obtained with an arterial catheter and therefore, the measurement performance is not clinically acceptable. Moreover, a high malfunction rate makes the device unsuitable for use in perioperative period.

People’s Hospital Of Huishan

To explore the mechanism of hypertension caused by sorafenib in liver cancer-bearing rats based on Vascular Endothelial-Growth Factor (VEGF) signal pathway. After the three groups (blank, liver cancer and Spontaneously Hypertensive Rat (SHR) groups, n = 30) were administered orally with sorafenib (2 mg/kg), the non-invasive tail arterial pressure measurement was employed to determine the changes in blood pressure (BP). Enzyme-linked immunosorbent assay measured the changes of VEGF and Nitric Oxide (NO) in serum. The expressions of Kinase insert Domain Receptor tyrosine kinase (KDR-CD), endothelial Nitric Oxide Synthase (eNOS), Bax and Bcl-2 were detected by Western blot. TUNEL assay detected the Apoptosis Index (AI) of cardiomyocyte. CD31 immunohistochemical staining was observed the changes of Myocardial Capillary Density (MCD). The BP and VEGF levels of the blank and SHR groups were not significantly (P > 0.05) different from those in the before treatment cohort, while the BP of the liver cancer group was significantly (P < 0.05) higher. VEGF level was significantly (P < 0.05) lower than before. Compared with the blank group, the levels of NO, KDR-CD, eNOS, Bcl-2/Bax and MCD in the liver cancer group were significantly (P < 0.05) lower than those in the after administration, while the myocardial cell AI increased significantly (P < 0.05). After antagonist intervention, the BPs and myocardial AI of the liver cancer and SHR groups were significantly lower than before the intervention. Besides, levels of KDR-CD, eNOS, Bcl-2/Bax protein, MCD, serum VEGF and NO were significantly higher than before the intervention (P<0.05). Induction mechanism of hypertension induced by sorafenib may be owing to the inhibition of the VEGF signaling pathway, and reduction of endothelial cells proliferation leading to blockade of NO synthesis. This causes vasoconstriction, while promoting myocardial cell apoptosis and decreasing capillary density, thereby inducing the occurrence of hypertension.

Perioperative Hemodynamic Monitoring: An Overview of Current Methods.

Perioperative hemodynamic monitoring is an essential part of anesthetic care. In this review, we aim to give an overview of methods currently used in the clinical routine and experimental methods under development. The technical aspects of the mentioned methods are discussed briefly. This review includes methods to monitor blood pressures, for example, arterial pressure, mean systemic filling pressure and central venous pressure, and volumes, for example, global end-diastolic volume (GEDV) and extravascular lung water. In addition, monitoring blood flow (cardiac output) and fluid responsiveness (preload) will be discussed.

Noninvasive continuous arterial pressure monitoring during anesthesia induction in patients undergoing cardiac surgery.

Objective:In this study we compared noninvasive arterial pressure measurement using ClearSight™ vascular-unloading-technique (Edwards Lifesciences Corp, Irvine, CA) with invasive arterial pressure measurement during induction of anesthesia undergoing mayor cardiac surgery.Design:Prospective, monocentric.Setting:University hospital.Participants:54 patients undergoing mayor cardiac surgery.Interventions:During induction all patients were simultaneously monitored with invasive (reference method) and noninvasive arterial pressure measurement (test-method) over a mean time period of 27 minutes.Measurements and Main Results:We observed slightly lower systolic and mean arterial pressures noninvasive than invasive. For systolic arterial pressure the mean of the differences was -18,05 mmHg (p < 0,05, SD ±16,78 mmHg), the mean arterial pressure MAP -5,47 mmHg (p < 0,05, SD ±11,08 mmHg) and for diastolic pressure -1,09 mmHg (p < 0,05, SD±11,15 mmHg),. The mean of the differences in heartrate was 1,15 (p < 0,05, SD±6,9 mmHg). When considering all measured values of the invasively measured MAP and the ClearSight ™ -MAP at the same timestamp over the recording interval, an almost identical progress can be seen that indicates a sufficient mapping of the hemodynamic changes. The percentage error for mean arterial, systolic and diastolic pressure measured by ClearSight™ amounts to 25,95 %, 26,77 % and 34,16 %, respectively.Conclusions:We conclude that ClearSight ™ is a good option for hemodynamic monitoring during induction of anesthesia. Taking into account the limitations, non-invasive arterial blood pressure measurement offers sufficient security to safely initiate anesthesia, especially when MAP is of particular interest. The use of non-invasive arterial blood pressure measurement with ClearSight ™ during induction of anesthesia in patients scheduled for major cardiac surgery is reliable and easy to use.

Perioperative Continuous Noninvasive Arterial Pressure Monitoring for Neuroendovascular Interventions: Prospective Study for Evaluation of the Vascular Unloading Technique

Blood pressure monitoring is crucial during neuroendovascular procedures. Intraoperative hemodynamic instability is associated with complications, which underscores the importance of continuous monitoring. Although direct measurement with an intra-arterial catheter is the gold standard for determining arterial pressure, it is costly, time-consuming, and associated with complications. The novel ClearSight system offers a noninvasive technique for monitoring arterial pressure via a finger cuff. This study compared noninvasive arterial pressure measurements with the gold standard method. Simultaneous recording of noninvasive and invasive arterial pressure was performed in patients undergoing neuroendovascular interventions. Both techniques were compared employing linear regression, Lin's correlation coefficient, Bland-Altman, and error grid analysis. The study enrolled 24 consecutive patients. The concordance correlation coefficient between both methods was 0.3526 (95% confidence interval [0.3134, 0.3906]) for mean arterial pressure and 0.4680 (95% confidence interval [0.4353, 0.4995]) and for systolic arterial pressure. The mean (SD) of the differences was 0.81 (17.86) mm Hg (95% limits of agreement [-52.52, 54.14]) for mean arterial pressure and 5.38 (14.64) mm Hg (95% limits of agreement [-45.12, 56.08]) for systolic arterial pressure. Error grid analysis demonstrated that the majority of measurements lie in regions with no or low risk for patients (mean arterial pressure, 71.0% and 24.4%; systolic arterial pressure, 59.2% and 25.8%). The ClearSight system provided accurate measurements of arterial blood pressure compared with invasive methods and within safe clinical parameters. This method may serve as a safe and reliable alternative for invasive blood pressure monitoring during neuroendovascular procedures.

From palpation of the pulse to cuff-free methods: evolution of arterial pressure measurement methods

The arterial pressure is an important physiological indicator. The review describes the different techniques of measurement of arterial pressure, their advantages and limitations. Moreover, it also represents a historical reference about the main stage of the development of clinical sphygmomanometrya that nowadays is a relevant method for measuring arterial pressure. The emergence and the development of devices for daily monitoring of arterial pressure and modern techniques for non-invasive arterial pressure measurement are described too.

Continuous noninvasive monitoring of arterial pressure using the vascular unloading technique in comparison to the invasive gold standard in elderly comorbid patients: A prospective observational study.

Background and AimsElderly patients aged ≥65 years represent a growing population in the perioperative field, particularly orthopedic and vascular surgery. The higher degree of age‐related or comorbid‐dependent vascular alterations renders these patients at risk for hemodynamic complications and likely denote a possible limitation for modern, non‐invasive arterial pressure monitoring devices. The aim was to compare vascular unloading technique‐derived to invasive measurements of systolic (SAP), diastolic (DAP), and mean arterial pressure (MAP) in elderly perioperative patients.MethodsThis prospective observational study included patients aged ≥65 years scheduled for orthopedic and patients ≥50 years with peripheral artery disease Fontaine stage ≥ II scheduled for vascular surgery, respectively. Invasive radial artery and non‐invasive finger‐cuff (Nexfin system) arterial pressures were recorded before and after induction of general anesthesia and during surgery. Correlation, Bland‐Altman, and concordance analyses were performed. Measurements of arterial pressure were also compared during intraoperative hypotension (MAP <70 mm Hg) and hypertension (MAP >105 mm Hg).ResultsSixty patients with orthopedic (N = 25, mean (SD) age 77 (5) years) and vascular surgery (N = 35, age 69 [10] years) were enrolled. Seven hundred data pairs of all patients were analysed and pooled bias and percentage error were: SAP: 14.43 mm Hg, 43.79%; DAP: −2.40 mm Hg, 53.78% and MAP: 1.73 mm Hg, 45.05%. Concordance rates were 84.01% for SAP, 77.87% for DAP, and 86.47% for MAP. Predefined criteria for interchangeability of absolute and trending values could neither be reached in the overall nor in the subgroup analyses orthopedic vs vascular surgery. During hypertension, percentage error was found to be lowest for all pressure values, still not reaching predefined criteria.ConclusionArterial pressure monitoring with the vascular unloading technique did not reach criteria of interchangeability for absolute and trending values. Nevertheless, the putatively beneficial use of noninvasive arterial pressure measurements should be further evaluated in the elderly perioperative patient.

Marker profile of myocardial remodeling in different etiopathogenetic forms of arterial hypertension in the experiment

The aim was to determine the morphodensitometric parameters of cardiomyocytes and features of the marker profile of remodeling in the left ventricular myocardium of rats with experimental hypertension of different etiopathogenetic forms.Materials and methods. The experiment was conducted on 20 male Wistar rats and 10 SHR which were divided into two groups of 10 animals each: the 1st –control; the 2nd – rats of the SHR line (EAH); the 3rd – 10 male Wistar rats with endocrine-salt arterial hypertension. Systolic and diastolic BP levels were measured in all the rats using the system of non-invasive arterial pressure measurement BP-2000. The objects of the study were myocardial sections in which the content of immunoreactive material to remodeling markers (cardiotrophin-1, titin, collagen type I, annexin V) was determined by the immunofluorescent method, titin / collagen ratio was calculated, the average linear size of cardiomyocyte nuclei, their density, RNA concentrations in the nucleus and cytoplasm were determined by morphodensitometric method.Results. Arterial hypertension, regardless of its etiopathogenetic form, is characterized by an increase in the number of cardiomyocyte nuclei with an increase in their size, decrease in the density and decrease in their RNA concentration against increase in the cytoplasm. In rats with EAH, the content of cardiotrophin-1 was higher than the control by 27 %, and in ESAH by 80 %. Titin levels were 12% higher in EAH and 46 % in ESAH. The collagen type I content of EAH was higher than the control by 49 %, while in the group with ESAH by 68 %. EAH rats had a higher annexin V content by 58 %, while ESAH – 64 %. The ratio of the content of titin and type I collagen in control rats was 1.01, in rats with EAH decreased to 0.76, while in rats ESAH it was 1.3.Conclusions. The formation of arterial hypertension, regardless of its etiopathogenetic form, leads to the development of pathological myocardial remodeling, as indicated by increased heart mass and specific gravity, changes in the cytoarchitectonics of cardiomyocytes, the development of polymorphism of their nuclei with increasing size against increasing of its number with nuclear dysfunction. The marker profile of myocardial remodeling in rats with essential hypertension is characterized by a moderate increase in cardiotrophin-1 and titin, with a significant increase in collagen type I and annexin V, which in combination with a low ratio of titin / collagen type indicates fibrosis with increased myocardial stiffness and the development of hypertrophic-fibrous type of myocardial remodeling with moderate apoptosis. In rats with endocrine-salt arterial hypertension, the marker profile of myocardial remodeling is characterized by a significant increase in all 4 immunohistochemical markers of remodeling, moderate fibrosis and an increase in the titin / collagen ratio, which is characteristic of hypertrophic-apoptotic type of pathological remodeling.

Pathogenetic features of the nitric oxide system state in the left ventricular myocardium of the rats with experimental arterial hypertension

The aim was to determine the pathogenetic features of the NO system in the myocardium of the left ventricle in the rats with endocrine-salt hypertension.Material and methods. The experiment was conducted on 20 male rats 220-290 g weight, 6–10 months old which were divided into 2 experimental groups: 1st – the control group (10 intact normotensive male Wistar rats); 2nd – 10 male Wistar rats with endocrine-salt arterial hypertension. Systolic and diastolic BP levels were measured in all the rats using a system of non-invasive arterial pressure measurement BP-2000. The objects of study in the experimental animals were blood plasma in which the nitrotyrosine level was measured, and the fragment of left ventricle, which was divided into two parts, one of which was homogenized using a Silent Crusher S homogenizer (Heidolph, Germany), in which nitrites level was determined. Concentration of immunoreactive material to NOS isoforms was detected with immunofluorescence method. The study of NOS mRNA isoforms expression in the left ventricular myocardium homogenates was carried out using a real-time polymerase chain reactionResults. In the experiment, an increase in all 3 isoforms and their mRNA was obtained. In the study, a decrease in nitrites concentration and a significant increase in nitrotyrosine levels, indicates the development of nitroso-oxidative stress.Conclusions. The development of experimental endocrine-salt hypertension in the Wistar rats leads to a stable increase in mean blood pressure by 65 % compared to control. Endocrine-salt arterial hypertension in Wistar rats is characterized by an increased mRNA content of all three isoforms of nNOS, eNOS and iNOS by 2.7, 2.8 and 5.7 times, respectively, compared to the control; increased expression of immunoreactive material to isoforms in transverse fibers by 14.3 %, 16.2 % and 18.5 %, respectively; in longitudinal fibers IRM to nNOS was higher by 8.3 %, to iNOS - by 8. 5%, but to eNOS it was lower by 7.6 %. At the same time, nitrites level decreased by 11.7 % and nitrotyrosine concentration was significantly higher, exceeding the control value by 88.5 %.

Noninvasive measurement of arterial blood pressure in patients with continuous-flow left ventricular assist devices: a systematic review.

Accurate mean blood pressure determination is essential to prevent adverse events in patients with continuous-flow left ventricular assist devices (CFLVAD). We sought to evaluate the accuracy of noninvasive methods of blood pressure measurement compared with invasive intra-arterial recordings in patients with CFLVAD. Systematic electronic search was performed on four online databases (PubMed, Scopus, Embase, and Web of Knowledge) for the terms "Blood Pressure" AND ("Heart-Assist Devices" OR "Left ventricular Assist Devices"). Only studies that compared an intra-arterial and noninvasive blood pressure measurement were included. Electronic search of scientific literature identified 5968 articles. After deduplication, screening of titles and abstracts, full-text review, and excluding incorrect populations and comparator, a total of 12 studies with 502 participants were included, of those 402 participants who had intra-arterial blood pressure measurement. Doppler mean arterial blood pressure showed a very high correlation with mean intra-arterial blood pressure (r = 0.97, r = 0.87) in low pulsatility situations. When the pulsatility was not evaluated, the correlation was high moderate (r = 0.63, r = 0.741). In low pulsatility situations, the correlation was moderate to high moderate (r = 0.42 to r = 0.65). Oscillometer automatic blood pressure cuff showed a moderate to very high correlation with intra-arterial mean arterial blood pressure (r = 0.42, r = 0.86) but also could be low in the context of low pulsatility associated with inconsistent success in noninvasive measurement (r = 0.25). Studies correlating intra-arterial with noninvasive techniques were performed in the context of routine clinical care using fluid-filled catheters. The degree of correlation between both methods is at least moderate.

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.

Accuracy of Non-Invasive Measurement of Mean Arterial Blood Pressure in Patients with Continuous Flow Left Ventricular Assist Devices: A Systematic Review

To determine the accuracy of non-invasive blood mean blood pressure (MAP) assessment in patients with continuous flow left ventricular assist devices. Systematic electronic search was performed on four online databases (PubMed, Scopus, Embase, and Web of Knowledge) for the terms "Blood Pressure" AND ("Heart-Assist Devices" OR "Left ventricular Assist Devices"). Only studies where a non-invasive blood pressure measurement was compared with intra-arterial blood pressure recording were included. A total of 12 studies with 502 participants were included, of those 402 had intra-arterial blood pressure measurement. The median number of participants per study was 30.5 (range: 5-154). The mean age of participants was 53 years old and 77% were male. All were single center prospective studies and intra-arterial blood pressure recordings were performed in the context of routine medical care in the Intensive Care Unit. Characteristics of the included studies are shown in figure 1. Intra-arterial recording was obtained using fluid filled catheter in all studies. Statements regarding the leveling and calibration of transducer 6 (50%) studies. Simultaneous recording occurred in 4 (30%) studies. The correlations between non-invasive and intra-arterial recordings are shown in Figure 2 CONCLUSION: Standardization of quality of signal acquisition and assessment of pulsatility was variable among studies. Non-invasive MAP has variable accuracy and this may adversely influence patients outcomes.

The electrocardiogram of ventricular capture during transcutaneous cardiac pacing

BackgroundTranscutaneous cardiac pacing (TCP) is deeply entwined with the problem of assessing ventricular capture on the electrocardiogram (ECG). We sought clarification of ventricular capture during TCP. MethodsWe studied one hundred and ten patients (75 ± 12 years) with bradycardia who underwent pacemaker or implantable cardioverter-defibrillator implantation. The cohort was stratified by structural heart disease (SHD) status and presence of narrow or wide QRS during spontaneous heart rhythm. We compared 12-lead ECG data at baseline (48 ± 7 beats/min) with those of TCP as well as of transvenous pacing (TVP) at a similar increased heart rate (76 ± 9 beats/min) to ensure constant ventricular capture. The QT interval was corrected for heart rate (QTc) using Bazett's method as well as by the Hodge's and Rautaharju's formulae depending on the presence of narrow or wide QRS at baseline. Electromechanical coupling was assessed by noninvasive arterial pressure measurement. ResultsTCP (median 80 mA) produced a QRS pattern resembling left bundle branch block. Overall, both TCP and TVP induced significant QRS and QTc prolongations when compared with baseline measures (p < 0.001). TCP created narrower QRS than TVP in those patients with SHD and narrow QRS (p < 0.006). There was no significant QTc duration difference between TCP and TVP. Mean arterial pressure underwent similar significant decrease following either TCP or TVP over baseline (p < 0.001), without difference between the two pacing approaches in any patient group. ConclusionTCP is associated with similar ECG and hemodynamic responses to those of TVP, regardless of the presence of SHD.

Hypotensive episodes on program hemodialysis during dialysis procedure: modern approach for diagnostics, prophylaxis and correction

The study objective is to evaluate the effectiveness of different approaches to correction and prevention of arterial hypotension episodes in patients undergoing long-term hemodialysis (HD). Materials and methods. The study included 35patients undergoing long-term hemodialysis in the dialysis center. In all patients, automatic non-invasive measurement of arterial pressure (AP) was performed using a built-in option of the “artificial kidney” device. Prior to the study, all patients underwent clinical test with evaluation of “dry weight” and bioelectrical impedance analysis. Crossover design was used in the study: at the beginning, hypotensive episodes were corrected in all patients using the standard method (the first 4 hemodialysis procedures); then during the following 4 procedures in addition to standard methods a computer algorithm automatically controlling ultrafiltration rate using an automatic system of pressure control (ASPC) with constant AP monitoring (AP was measured prior to hemodialysis and after it and at least 1 time in the first 5 min of the procedure; from the 4h procedure onwards, intervals were determined by the algorithm automatically) was used. Values of mean AP during hemodialysis procedures for the whole monitoring period were analyzed. The duration of the study was 3 weeks for all patients. Results . Mean pre-dialysis systolic and diastolic AP in the patients for the standard approach was 124.6 ± 27.7 and 74.5 ± 21.1 mm Hg, post-dialysis AP was 114.4 ± 24.4 and 71.3 ± 16.3 mm Hg, respectively. For ASPC, pre-dialysis and post-dialysis AP was statistically significantly higher than for the standard approach: 133.2 ± 21.3 and 79.3 ± 15.8 mm Hg (p &lt;0.001; p = 0.009), 125.7 ± 23.9 and 75.9 ± 18.3 mm Hg (p &lt;0.001; p &lt;0.001). Detailed analysis of intra-dialysis AP measured during the standard approach showed that it was 110.2 ± 17.3 and 68.3 ± 13.9 mm Hg. Using ASPC, intra-dialysis AP was significantly higher: 124 ± 20.5 and 75.9 ± 14.2 mm Hg (p = 0.03; p = 0.02). Mean AP was also higher: 82.5 ± 13.9 mm Hgfor the standard approach versus 91.5 ± 15.6 mm Hg (p = 0.01) for ASPC. The ultrafiltration rates were slightly higher without ASPC (8.2 ml/kg/hour vs. 7.9 ml/kg/hour). Therefore, it was shown that the use of ASPC in addition to standard methods of hypotension correction is effective and safe. There weren»t any significant differences in «hemodialysis-dose effectiveness» (Kt/V) in both groups; however, in the ASPC group target values of inorganic phosphorus in serum (for a dialysis patient) were reached which is one of the most important parameters of hemodialysis adequacy. Concentration of inorganic phosphorus for the ultrafiltration control algorithm was 1.5 mmol/l, for the standard dialysis program — 1.8 mmol/l which shows benefits of ASPC. This data didn»t reach statistical significance (p = 0.07) which likely can be attributed to a low number of observations. Conclusion . Intra-dialysis hypotension with high ultrafiltration rates is a frequent and potentially dangerous complication of hemodialysis which negatively affects patients» long-term prognosis mainly due to an increase in cardiovascular morbidity and mortality. A new method for prevention and correction of hypotension using ASPC allows to decrease ultrafiltration rate on time preventing a hypotensive episode, decreasing its rates and improving attainment of AP target values (both pre- and post-dialysis) as well as intra-dialysis variation during dialysis procedure.

A novel approach for non-invasive measurement of mean arterial pressure using pulse transit time

Recent days many researches are carried out related to the heart of the human. As a result many remedies are found for the various heart disorders. Electrocardiography (ECG) is the exertion of the electrical response from heart by placing the electrodes over the chest. The Einthoven triangle is an imaginary formation of the three leads in the triangle used in electrocardiography; by that technique of placement of electrode we can analysis the electrocardiogram of the heart. The waveform is also known as PQR waveform which contains the information of arterial repolarization, arterial polarization, ventricular repolarization and ventricular polarization. In general the BP monitor is carried out using oscillometry. In the existing system separate techniques and devices are used to measure electrocardiography and BP. The proposed system is to integrate both electrocardiography and blood pressure measurement by means adopting transit pulse time. It is defined as the systematic time lay off betwixt oscillometric pulses and peaks of ECG especially R peaks of it. The major advantage of the system is to exhibit non-zero crossing and gives more accurate result. The mean arterial pressure estimation is done by using MatLab which is the unique estimation method for measuring pulse transit time interval. Thus the non invasive system designed which reduce the cuff deviations and errors in electrocardiography. It can be applied in detecting the arterial disorders at most efficient manner.

Method of deflection corrected tonometry with phantom vessel experiments

BackgroundThe Continuous Non-Invasive measurement of arterial Blood Pressure [CNIBP] is possible via the method of arterial tonometry and the arterial volume clamp methods. Arterial tonometry successfully measures continuous arterial pressure but requires large vessel deformation and a highly miniaturized pressure sensor to obtain a direct calibration of pressure. A properly designed tonometer is capable of achieving pressure accuracy of less than 5% error at the radial artery. The volume clamp method achieves comparable errors but is generally restricted to the very peripheral arteries. Since the brachial or radial arteries are preferable sites to record blood pressure, tonometry is generally preferred. However, due to its strict operating requirements, tonometry requires a highly skilled operator. The greatest source of measurement error results from slight deviation from the artery wall applanation position. In this study, a method for correcting tonometry deflection error is introduced and evaluated using preliminary experiments. Methods-modelingIn prior analysis it has been shown that arterial wall flattening causes contact stress to become uniform and equal to the arterial pressure. In this article, we derive the contact stress for deflections other than the ideal applanation position and to allow variable vessel deflection. This analysis permits the contact stress to be corrected for tonometer positions that are not exact so that pressure accuracy is maintained in spite of less than ideal positioning. This will alleviate the necessity for highly skilled users and allow rapid determination of the pulse pressure. Methods-experimentalExperiments were performed to evaluate applied model corrections for tonometer accuracy versus vessel deflection. Two experiments were performed to evaluate tonometer accuracy when deflection is varied. The first experiment used no deflection correction and the second experiment applied model derived deflection correction. A force sensor was used to deflect a phantom latex vessel of known internal pressure. The corrected contact pressure was then compared with known pressures to evaluate the pressure accuracy. Results-modelinga geometric model was derived for vessel contact area versus deflection. This resulted in a formula that provides contact area continuously for any amount of deflection. Once the contact area is known the average tonometer contact pressure was obtained that corresponds with the vessel internal pressure. Results – experimentalA latex tubing phantom vessel was pressurized to a known amount and was deflected in increments over its full diameter while measuring contact force at each position. The model-derived formula was then used to calculate pressure at each position. The calculated pressure was then compared with known internal pressure to evaluate pressure accuracy for all the phantom pressure and deflection points. ConclusionsA modeling method for tonometer deflection correction was derived and evaluated using a phantom vessel. Average error was significantly reduced over the non-corrected data. The variability of error was also reduced for all data points collected. The experiments reveal that blood pressure measurement error can be reduced to levels obtained in near ideal tonometry conditions without the need for precise position control. The relaxed user precision is anticipated to simplify the use and design requirements for arterial tonometry in practice.

Milk plus Carbohydrate Supplementation during Interval Walking Training Enhanced the Improvement of Blood Glucose and Blood Pressure Regulations in Older People

AimsWe examined whether the milk + carbohydrate (CHO) supplementation during interval walking training improved the symptoms of lifestyle‐related diseases with enhanced methylation of the pro‐inflammatory gene, NFKB2.MethodsTwenty nine subjects (~70 yr) having performed interval walking training for &gt;6 months but with &gt;130 mmHg of systolic pressure and &gt;110 mg/dl of blood glucose participated in the study. After the baseline measurements of peak aerobic capacity (VO2peak) by graded walking test, blood constituents, blood glucose by continuous method (iPro2R), and carotid arterial compliance with Doppler ultrasound (Vivid7R) and non‐invasive arterial pressure measurement (FinometerR), we randomly divided subjects into two groups: MILK (6 men, 9 women) and CNT (6 men, 8 women) consuming either milk (10 g protein and 9.5 g CHO) + CHO (8.8 g) or CHO (7 g) alone during 5‐month interval walking training, respectively. After the training, we measured the same variables as before.ResultsIn MILK, VO2peak and carotid arterial compliance increased and mean blood glucose decreased with a reduced fluctuation after standardized meal intake during the day (all, P&lt;0.05); however, these changes were minimal in CNT (all, P&gt;0.06). This was accompanied by enhanced methylation of NFKB2 in MILK than CNT (P=0.045).ConclusionsMilk + CHO supplementation during interval walking training enhanced the improvement of lifestyle‐related diseases with enhanced NFKB2 methylation.Support or Funding InformationThis study was supported by a grant from the Japan Society for the Promotion of Science (15H01830).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.