Principles and techniques of blood pressure measurement

Effects of arm elevation on radial artery pressure: a new method to distinguish hypovolemic shock and septic shock from hypotension

OBJECTIVES

In this prospective observational study, we investigated the variability in radial artery invasive blood pressure associated with arm elevation in patients with different hemodynamic types.

PATIENTS AND METHODS

We carried out a prospective observational study using data from 73 general anesthesia hepatobiliary postoperative adult patients admitted to an ICU over a 1-year period. A standard procedure was used for the arm elevation test. The value of invasive radial arterial pressure was recorded at baseline, and 30 and 60 s after the arm had been raised from 0° to 90°. We compared the blood pressure before versus after arm elevation, and between hemodynamically stable, hypovolemic shock, and septic shock patient groups.

RESULTS

In all 73 patients, systolic arterial pressure (SAP) decreased, diastolic arterial pressure (DAP) increased, and pulse pressure (PP) decreased at 30 and 60 s after arm elevation (P<0.01), but the mean arterial pressure (MAP) was unchanged (P>0.05). On comparing 30 and 60 s, there was no significant difference in SAP, DAP, PP, or MAP (P>0.05). In 40 hemodynamically stable patients, SAP and PP decreased, and DAP and MAP increased significantly at 30 and 60 s after arm elevation compared with baseline (P<0.01). In 16 hypovolemic patients, SAP, DAP, and MAP increased significantly compared with baseline at 30 and 60 s (P<0.01), but PP was unchanged (P>0.05). In 17 patients with septic shock, SAP, PP, and MAP decreased significantly versus baseline at 30 and 60 s (P<0.01), but DAP was unchanged (P>0.05). Comparison of the absolute value of pressure change of septic shock patients at 30 s after raising the arm showed that SAP, DAP, and MAP changes were significantly lower compared with those in hypovolemic shock and hemodynamically stable patients (P<0.01). The areas under the receiver operator characteristic curve for predicting septic shock was 0.930 [95% confidence interval (CI): 0.867-0.992, P< 0.001] for change value at 30 s after arm elevation of SAP. The best cut-off point for the SAP change value was -5 mmHg or less, with a sensitivity of 94.12%, a specificity of 80.36%, a positive likelihood ratio of 4.79 (95% CI: 2.8-8.2), and a negative likelihood ratio of 0.073 (95% CI: 0.01-0.5).

CONCLUSION

Our study shows that hypovolemic shock and septic shock patients have significantly different radial artery invasive blood pressure changes in an arm elevation test, which could be applied as a new method to distinguish hypovolemic shock and septic shock from hypotension.

Design and Simulation of an Integrated Wireless Capacitive Sensors Array for Measuring Ventricular Pressure

This paper reports the novel design of a touch mode capacitive pressure sensor (TMCPS) system with a wireless approach for a full-range continuous monitoring of ventricular pressure. The system consists of two modules: an implantable set and an external reading device. The implantable set, restricted to a 2 × 2 cm² area, consists of a TMCPS array connected with a dual-layer coil, for making a reliable resonant circuit for communication with the external device. The capacitive array is modelled considering the small deflection regime for achieving a dynamic and full 5⁻300 mmHg pressure range. In this design, the two inductive-coupled modules are calculated considering proper electromagnetic alignment, based on two planar coils and considering the following: 13.56 MHz frequency to avoid tissue damage and three types of biological tissue as core (skin, fat and muscle). The system was validated with the Comsol Multiphysics and CoventorWare softwares; showing a 90% power transmission efficiency at a 3.5 cm distance between coils. The implantable module includes aluminum- and polyimide-based devices, which allows ergonomic, robust, reproducible, and technologically feasible integrated sensors. In addition, the module shows a simplified and low cost design approach based on PolyMEMS INAOE^® technology, featured by low-temperature processing.

Robust motion artefact resistant circuit for calculation of Mean Arterial Pressure from pulse transit time

Cuff-less and non-invasive methods of Blood Pressure (BP) monitoring have faced a lot of challenges like stability, noise, motion artefact and requirement for calibration. These factors are the major reasons why such devices do not get approval from the medical community easily. One such method is calculating Blood Pressure indirectly from pulse transit time (PTT) obtained from electrocardiogram (ECG) and Photoplethysmogram (PPG). In this paper we have proposed two novel analog signal conditioning circuits for ECG and PPG that increase stability, remove motion artefacts, remove the sinusoidal wavering of the ECG baseline due to respiration and provide consistent digital pulses corresponding to blood pulses/heart-beat. We have combined these two systems to obtain the PTT and then correlated it with the Mean Arterial Pressure (MAP). The aim was to perform major part of the processing in analog domain to decrease processing load over microcontroller so as to reduce cost and make it simple and robust. We have found from our experiments that the proposed circuits can calculate the Heart Rate (HR) with a maximum error of ~3.0% and MAP with a maximum error of ~2.4% at rest and ~4.6% in motion.

Recent Research and Developing Trends of Wearable Sensors for Detecting Blood Pressure

Blood pressure is considered an index to measure a person's health or state. The IEEE published a standard for wearable cuffless blood pressure measuring devices, which was certified as IEEE1708 on 26 August 2014, and, according to this standard, the development of wearable devices based on blood pressure is expected in the future. Considering this, blood pressure should be detectable all the time and everywhere, and this can help improve health consciousness. In this review, we introduce the recent development of wearable blood pressure measuring devices and research trends, and present the future prospects for blood pressure measuring devices.

STUDY ON THE RELATIONSHIP BETWEEN WALL SHEAR STRESS AND ASPECT RATIO OF CEREBRAL ANEURYSMS WITH DIFFERENT PRESSURE DIFFERENCES USING CFD SIMULATIONS

CFD simulations were performed for 60 human cerebral aneurysms (30 previously ruptured and 30 previously unruptured) to study the behavior of the time-averaged wall shear stress (TAWSS) with respect to the aspect ratio (AR), implementing a set of low, normal, and high-pressure differences between the inlet and the outlets of each artery. It is well known that there exists a direct relationship between TAWSS and the rupture. In this investigation, we presented an important result because the condition of the pressure among the branches and the AR may be measured in any patient, then a slope may be associated, and finally a TAWSS may be estimated. We found that when the pressure difference increased, the absolute slopes between TAWSS and AR increased as well. Also, the magnitude of the slope in the previously unruptured aneurysms was 4.7 times the slope in the previously ruptured aneurysms. On the other hand, TAWSS was higher in the previously unruptured aneurysm than previously ruptured aneurysms due to the unruptured aneurysms that have a smaller surface area. Furthermore, we analyzed the relationship between TAWSS and other geometric parameters of the aneurysm, such as bottleneck and non-sphericity index; however, no correlation was found for either cases.

Clinical value of ambulatory blood pressure in pediatric patients after renal transplantation

Hypertension is a highly prevalent co-morbidity in pediatric kidney transplant recipients. Undertreated hypertension is associated with cardiovascular complications and negatively impacts renal graft survival. Thus, the accurate measurement of blood pressure is of the utmost importance for the correct diagnosis and subsequent management of post-renal transplant hypertension. Data derived from the general population, and to a lesser extent from the pediatric population, indicates that ambulatory blood pressure monitoring (ABPM) is superior to blood pressure measurements taken in the clinical setting for the evaluation of true mean blood pressure, identification of patients requiring antihypertensive treatment, and in the prediction of cardiovascular outcome. This Educational Review will discuss the clinical value of ABPM in the identification of individual blood pressure phenotypes, i.e., normotension, new-onset hypertension, white-coat hypertension, masked hypertension, controlled blood pressure, and undertreated/uncontrolled hypertension in pediatric kidney transplant recipients. Finally, we examine the utility of performing repeated ABPM for treatment monitoring of post-renal transplant hypertension and on surrogate markers related to relevant clinical cardiovascular outcomes. Taken together, our review highlights the clinical value of the routine use of ABPM as a tool for identifying and monitoring hypertension in pediatric kidney transplant recipients.

Establishment of blood pressure nomograms representative for Egyptian children and adolescents: a cross-sectional study

OBJECTIVE

To define nomograms for blood pressure in Egyptian children and adolescents.

METHODS AND STUDY DESIGN

A total of 60 025 Egyptian children from birth to 19 years were enrolled in this cross-sectional randomised study from December 2015 to March 2017. They were selected from diverse geographical districts in Egypt. Healthy children who fulfilled the inclusion criteria, which included good nutritional history, absence of fever or documented underlying disease at the time of examination, no evidence of haemodynamically significant illness, and no antihypertensive drugs or other chronic drug administration, were included in the study. Body weight, recumbent length (for less than 24 months) and height (from 2 years to 19 years), and blood pressure were measured using standard mercury sphygmomanometers.

RESULTS

Blood pressure increases with age in both boys and girls. The 90th percentile of systolic and diastolic blood pressure among Egyptian children was different from other ethnic populations (American and Turkish children) in both sexes. Systolic and diastolic blood pressure showed a positive correlation with weight and height in both sexes (p<0.001).

CONCLUSION

We assumed that normal blood pressure curves should be used cautiously during childhood, and it is recommended that every population have its own normal standard curve to define measured blood pressure levels in children. These centiles increased our knowledge and awareness of normal blood pressure among Egyptian children and adolescents. The percentiles will distinguish children and young adolescents with increased blood pressure and will be of value to both medical practice and scientific research.

BP Measurement Techniques: What They Mean for Patients with Kidney Disease

Patients with CKD typically have hypertension. Manual BP measurement in the office setting was used to define hypertension, establish eligibility, and assess BP targets in the epidemiologic studies and early randomized, controlled trials that inform current management of hypertension. Use of automated oscillometric devices has largely replaced manual BP measurement in the office and clinical trials. These newer devices may reduce the white coat effect and facilitate guideline-adherent measurement protocols. Obtaining BP measurements outside of the office with home and ambulatory BP monitoring is now more common. Out of office BPs are especially important in patients with CKD, because reduced GFR and proteinuria are associated with masked hypertension (normal office BP and elevated BP outside of the office), elevated nighttime BP, and abnormal diurnal variation in BP, all of which are associated with higher risk for target organ damage and adverse outcomes. Also, it is now feasible to routinely measure central BP and central hemodynamics. These measures are of greater importance to patients with CKD given the higher prevalence of increased sympathetic tone, arteriosclerosis, and inflammation as well as impaired sodium excretion and endothelial dysfunction, which lead to alterations in central BPs in this population. In this review, we describe various BP measurement techniques and how they apply to the care of patients with CKD.

Blood pressure measurement techniques: Assessing performance in outpatient settings of a tertiary-level hospital in Rwanda

Cardiovascular diseases (CVD) are the leading cause of mortality globally. Hypertension is a known modifiable risk factor for CVD. Diagnosis and management of hypertension hinges upon accurate blood pressure (BP) measurement. In this study, we assessed performance to recommended guidelines for BP measurement in Rwanda. In 2017, a cross-sectional study investigating performance on 11 techniques recommended for BP measurement was undertaken across outpatient settings of 3 departments at the University Teaching Hospital of Kigali, Rwanda. Performance was checked by an inside observer. The study enrolled 164 patients. The overall mean performance on the 11 BP measurement techniques was 5.69 (±1.02) out of the 11 possible points. There was no significant difference in performance across departments (P = .28). The findings suggest that performance on currently recommended guidelines for BP measurement is not optimal. Going forward, it is important to implement interventions that will enhance performance given that diagnosis and management of hypertension depend upon accurate BP measurement.

Heart Rate Variability following Combined Aerobic and Resistance Training in Sedentary Hypertensive Women: A Randomised Control Trial

Objective

To investigate the effect of combined aerobic and resistance training (CART) on heart rate variability in sedentary, hypertensive women.

Participants

A total of twenty-eight hypertensive (Stage 1 and 2) sedentary women (Age 40.54 ± 4.2 yrs; Height 155.14 ± 5.4 cm; Weight 70.96 ± 10.2 kg; BMI 29.6 ± 4.4; Duration of HTN: 6.43 ± 2.5 yrs) were recruited for the study.

Methods

Participants were randomly assigned to either the CART group that performed combined aerobic and resistance exercise of moderate intensity [aerobic exercise 50–80% of HR_max (maximum heart rate) and resistance exercises at 50–80% of 1 Repetition Maximum (RM)], 5 times/week for 4 weeks, or to the control group that followed conventional treatment without any supervised exercise intervention.

Main outcome measures

Resting blood pressure was measured and standard heart rate variability (HRV) indices were calculated using time domain (SDNN, pNN50, RMSSD) and frequency domain (LFnu, HFnu, LF/HF and TP) analysis.

Results

CART group demonstrated an increase in HFnu, TP, SDNN, and RMSSD, (p < 0.05) along with a significant decrease in LFnu, LF/HF ratio, systolic blood pressure, and diastolic blood pressure (p < 0.05).

Conclusion

CART showed significant improvement in HRV parameters indicating vagal dominance in middle-aged hypertensive women. Therefore, exercise training in combined form (aerobic and resistance) may be incorporated in the management programs of the patients suffering from hypertension in order to augment improvement in their cardiac autonomic control.

Baseline check of blood pressure readings of an automated device in severe pre-eclampsia and healthy normotensive pregnancy

OBJECTIVE

The baseline blood pressure (BP) readings of an automated device that have not been validated in pregnancy require comparison with those from a reference standard before the device is utilized in pregnancy. We aimed to perform a baseline check of BP readings of an automated device, Mindray iMEC12 patient monitor, in severe pre-eclampsia and healthy pregnancy.

STUDY DESIGN

The BP of 50 severe pre-eclamptic and 90 normotensive pregnancies were measured using Mindray iMEC12 patient monitor (test device) and Welch Allyn 767 aneroid sphygmomanometer (reference device). A pass in either the International Organization for Standardization (ISO) or British Hypertension Society (BHS) rating was considered acceptable. The cumulative percentage of absolute BP difference between the test and reference devices within 5, 10 and 15 mmHg were calculated to rate the test device according to the BHS grades (A, B, C or D). The ISO recommends that an accurate device should achieve a mean BP difference ± SD of ≤5 ± 8 mmHg.

RESULTS

The mean BP difference between the test and reference devices were 1.27 ± 7.51 mmHg and 0.05 ± 6.09 mmHg for systolic and diastolic BPs respectively. The test device achieved the BHS grades B and A rating in systolic and diastolic BPs respectively. In each of the 2 groups (pre-eclamptic and normotensive pregnancies), the test device also satisfied the set pass criteria.

CONCLUSIONS

In settings that do not have a validated BP device, Mindray iMEC12 patient monitor may be used for BP measurement in normotensive and severe pre-eclamptic pregnancies.

Accuracy of an oscillometric blood pressure monitor in anesthetized pigs

The purpose of this study is to evaluate the accuracy of an oscillometric blood pressure monitor in anesthetized pigs. Invasive blood pressure (IBP) and noninvasive blood pressure (NIBP) measurements were taken using a DRE Waveline Pro multiparameter monitor at four different time points in 17 pigs undergoing injectable anesthesia. NIBP measurements were taken on both the thoracic and pelvic limbs. Bland Altman analysis was used to assess agreement between methods and a linear mixed-effects model was used to evaluate the effect of cuff position and blood pressure on bias. Invasive systolic arterial pressure (SAP) ranged between 112 and 161 mmHg (mean ± SD: 138.8 ± 13.3; median: 139.5). Invasive diastolic arterial pressure (DAP) ranged between 60 and 104 mmHg (mean ± SD: 86.0 ± 9.1; median: 87.0). Invasive mean arterial pressure (MAP) ranged between 79 and 121 mmHg (mean ± SD: 103.2 ± 9.3; median 103.0). Only the diastolic and mean measurements obtained from the pelvic limb met criteria outlined by the American College of Internal Medicine for required accuracy of NIBP monitors. Bias was significantly higher in the thoracic limb in comparison to the pelvic limb and was significantly higher at blood pressures above median. In general, NIBP measurements underestimated IBP measurements. In conclusion, the use of the DRE Waveline Pro to assess NIBP in anesthetized pigs may be useful in monitoring trends in mean and diastolic blood pressure and is most accurate when used on the pelvic limb.

Quantitative Assessment of Blood Pressure Measurement Accuracy and Variability from Visual Auscultation Method by Observers without Receiving Medical Training

This study aimed to quantify blood pressure (BP) measurement accuracy and variability with different techniques. Thirty video clips of BP recordings from the BHS training database were converted to Korotkoff sound waveforms. Ten observers without receiving medical training were asked to determine BPs using (a) traditional manual auscultatory method and (b) visual auscultation method by visualizing the Korotkoff sound waveform, which was repeated three times on different days. The measurement error was calculated against the reference answers, and the measurement variability was calculated from the SD of the three repeats. Statistical analysis showed that, in comparison with the auscultatory method, visual method significantly reduced overall variability from 2.2 to 1.1 mmHg for SBP and from 1.9 to 0.9 mmHg for DBP (both p < 0.001). It also showed that BP measurement errors were significant for both techniques (all p < 0.01, except DBP from the traditional method). Although significant, the overall mean errors were small (−1.5 and −1.2 mmHg for SBP and −0.7 and 2.6 mmHg for DBP, resp., from the traditional auscultatory and visual auscultation methods). In conclusion, the visual auscultation method had the ability to achieve an acceptable degree of BP measurement accuracy, with smaller variability in comparison with the traditional auscultatory method.

Comparison of Direct and Indirect Methods of Measuring Arterial Blood Pressure in Healthy Male Rhesus Macaques (Macaca mulatta)

Blood pressure is a critical parameter for evaluating cardiovascular health, assessing effects of drugs and procedures, monitoring physiologic status during anesthesia, and making clinical decisions. The placement of an arterial catheter is the most direct and accurate method for measuring blood pressure; however, this approach is invasive and of limited use during brief sedated examinations. The objective of this study was to determine which method of indirect blood pressure monitoring was most accurate compared with measurement by direct arterial catheterization. In addition, we sought to determine the relative accuracy of each indirect method (compared with direct arterial measurement) at a given body location and to assess whether the accuracy of each indirect method was dependent on body location. We compared direct blood pressure measurements by means of catheterization of the saphenous artery with oscillometric and ultrasonic Doppler flow detection measurements at 3 body locations (forearm, distal leg, and tail base) in 16 anesthetized, male rhesus macaques. The results indicate that oscillometry at the forearm is the best indirect method and location for accurately and consistently measuring blood pressure in healthy male rhesus macaques.

A bundled quality improvement program to standardize clinical blood pressure measurement in primary care

We evaluated use of a program to improve blood pressure measurement at 6 primary care clinics over a 6-month period. The program consisted of automated devices, clinical training, and support for systems change. Unannounced audits and electronic medical records provided evaluation data. Clinics used devices in 81.0% of encounters and used them as intended in 71.6% of encounters, but implementation fidelity varied. Intervention site systolic and diastolic blood pressure with terminal digit "0" decreased from 32.1% and 33.7% to 11.1% and 11.3%, respectively. Improvement occurred uniformly, regardless of sites' adherence to the measurement protocol. Providers rechecked blood pressure measurements less often post-intervention (from 23.5% to 8.1% of visits overall). Providers at sites with high protocol adherence were less likely to recheck measurements than those at low adherence sites. Comparison sites exhibited no change in terminal digit preference or repeat measurements. This study demonstrates that clinics can apply a pragmatic intervention to improve blood pressure measurement. Additional refinement may improve implementation fidelity.

Measuring arterial blood pressure in humans: Auscultatory and automatic measurement techniques for human biological field studies

Human biologists have been examining arterial blood pressure since they began studying the effects of the environment and culture on the health of diverse populations. The Korotkoff auscultatory technique with a trained observer and aneroid sphygmomanometer is the method of choice for blood pressure measurement in many bioanthropological field contexts. Korotkoff sounds (the first and fifth phases) are the preferred determinants of systolic and diastolic pressure, even in infants, children, pregnant women, and the elderly. Training of observers, positioning of individuals, and selection of cuff size are all essential for obtaining standardized measurements. Automatic electronic devices are increasingly being used for blood pressure measurement in human biological studies. The automatic monitors often use the oscillometric method for measuring pressure, but must be validated before use. The emergence of automatic ambulatory blood pressure monitors has opened another avenue of research on blood pressure in human biology, where allostasis and circadian responses to environmental change and real life behavioral challenges can be defined and evaluated, largely because there is now the ability to make multiple measurements over time and in varying contexts. Stand-alone automatic monitors can also be substituted for manual auscultated readings in field contexts, although in studies where participants measure their own pressure, education about how the devices work and protocol specifics are necessary. Finally, computer-driven plethysmographic devices that measure pressure in the finger are available to evaluate short-term reactivity to specific challenges.

Bias, Confounding, and Interaction: Lions and Tigers, and Bears, Oh My!

Epidemiologists seek to make a valid inference about the causal effect between an exposure and a disease in a specific population, using representative sample data from a specific population. Clinical researchers likewise seek to make a valid inference about the association between an intervention and outcome(s) in a specific population, based upon their randomly collected, representative sample data. Both do so by using the available data about the sample variable to make a valid estimate about its corresponding or underlying, but unknown population parameter. Random error in an experiment can be due to the natural, periodic fluctuation or variation in the accuracy or precision of virtually any data sampling technique or health measurement tool or scale. In a clinical research study, random error can be due to not only innate human variability but also purely chance. Systematic error in an experiment arises from an innate flaw in the data sampling technique or measurement instrument. In the clinical research setting, systematic error is more commonly referred to as systematic bias. The most commonly encountered types of bias in anesthesia, perioperative, critical care, and pain medicine research include recall bias, observational bias (Hawthorne effect), attrition bias, misclassification or informational bias, and selection bias. A confounding variable is a factor associated with both the exposure of interest and the outcome of interest. A confounding variable (confounding factor or confounder) is a variable that correlates (positively or negatively) with both the exposure and outcome. Confounding is typically not an issue in a randomized trial because the randomized groups are sufficiently balanced on all potential confounding variables, both observed and nonobserved. However, confounding can be a major problem with any observational (nonrandomized) study. Ignoring confounding in an observational study will often result in a "distorted" or incorrect estimate of the association or treatment effect. Interaction among variables, also known as effect modification, exists when the effect of 1 explanatory variable on the outcome depends on the particular level or value of another explanatory variable. Bias and confounding are common potential explanations for statistically significant associations between exposure and outcome when the true relationship is noncausal. Understanding interactions is vital to proper interpretation of treatment effects. These complex concepts should be consistently and appropriately considered whenever one is not only designing but also analyzing and interpreting data from a randomized trial or observational study.

Significantly Reduced Blood Pressure Measurement Variability for Both Normotensive and Hypertensive Subjects: Effect of Polynomial Curve Fitting of Oscillometric Pulses

This study aimed to compare within-subject blood pressure (BP) variabilities from different measurement techniques. Cuff pressures from three repeated BP measurements were obtained from 30 normotensive and 30 hypertensive subjects. Automatic BPs were determined from the pulses with normalised peak amplitude larger than a threshold (0.5 for SBP, 0.7 for DBP, and 1.0 for MAP). They were also determined from cuff pressures associated with the above thresholds on a fitted curve polynomial curve of the oscillometric pulse peaks. Finally, the standard deviation (SD) of three repeats and its coefficient of variability (CV) were compared between the two automatic techniques. For the normotensive group, polynomial curve fitting significantly reduced SD of repeats from 3.6 to 2.5 mmHg for SBP and from 3.7 to 2.1 mmHg for MAP and reduced CV from 3.0% to 2.2% for SBP and from 4.3% to 2.4% for MAP (all P < 0.01). For the hypertensive group, SD of repeats decreased from 6.5 to 5.5 mmHg for SBP and from 6.7 to 4.2 mmHg for MAP, and CV decreased from 4.2% to 3.6% for SBP and from 5.8% to 3.8% for MAP (all P < 0.05). In conclusion, polynomial curve fitting of oscillometric pulses had the ability to reduce automatic BP measurement variability.

Continuous systolic and diastolic blood pressure estimation utilizing long short-term memory network

A novel blood pressure estimation method based on long short-term memory neural network, one of the recurrent neural networks being commonly used nowadays, is proposed in this paper for better chronic diseases monitoring. Along with the neural network, a newly proposed ambulatory blood pressure (ABP) processing technique called Two-stage Zero-order Holding (TZH) algorithm has also been presented in the paper. The proposed methodology has the advantages over traditional blood pressure estimation algorithms which are based on Pulse Transit time (PTT). The paper addresses the effectiveness of the algorithm by computing the Root-Mean-Squared Errors (RMSE) between the BP estimated and the ground truth. Our algorithm shows precise systolic blood pressure and diastolic blood pressure estimation with the average RMSE values in 2.751 mmHg and 1.604 mmHg respectively across the sample used. Experimental results suggest that BP estimation based on LSTM has great potential to be embedded into monitoring system for better accuracy and generalization.

Can blood pressure be measured during exercise with an automated sphygmomanometer based on an oscillometric method?

[Purpose] This study investigated the reliability of an automated sphygmomanometer based on an oscillometric method, when used during exercise. [Subjects and Methods] Ten healthy subjects were included. Blood pressure (BP) was measured with an automated sphygmomanometer based on a cuff-oscillometric method. The experiment consisted of five tests: sitting posture at rest, walking with swinging the upper limbs, walking without swinging the upper limbs, walking on a treadmill, and riding a bicycle ergometer. Right and left brachial artery BP was measured twice at the same times. If the difference in systolic BP on bilateral testing was less than 15 mmHg, it was judged to be accurate, and accurate measurement rates were calculated. [Results] BP could not be measured in most limbs on walking with swinging the upper limbs, walking without swinging the upper limbs, or walking on a treadmill. The accurate measurement rates in bilateral limbs were 95.0% in sitting posture at rest, 0.0% on walking with swinging upper limbs, 5.0% on walking without swinging upper limbs, 15.0% on walking on a treadmill, and 65.0% on riding a bicycle ergometer. [Conclusion] An automated sphygmomanometer based on an oscillometric method was useful for BP measurement only at rest.

Questionable accuracy of home blood pressure measurements in the obese population - Validation of the Microlife WatchBP O3® and Omron RS6® devices according to the European Society of Hypertension-International Protocol

OBJECTIVE

Two oscillometric devices, the Microlife WatchBP O3® and the Omron RS6®, designed for self-blood pressure measurement were evaluated according to the European Society of Hypertension (ESH)-International Protocol (IP) Revision 2010 in the obese population.

METHODS

The Microlife WatchBP O3 measures blood pressure (BP) at the brachial level and the Omron RS6 measures BP at the wrist level. The ESH-IP revision 2010 includes a total of 33 subjects. The difference between observers' and device BP values was calculated for each measure. A total of 99 pairs of BP differences were classified into three categories (≤5, ≤10, and ≤15 mmHg). The protocol procedures were followed precisely in each of the two studies.

RESULTS

Microlife WatchBP O3 and Omron RS6 failed to fulfill the criteria of the ESH-IP. The mean differences between the device and the mercury readings were: 0.3±7.8 mmHg and -1.9±6.4 mmHg for systolic BP and diastolic BP, respectively, for Microlife WatchBP O3, and 2.7±9.9 mmHg for SBP and 3.5±11.1 mmHg for diastolic BP for Omron RS6.

CONCLUSION

Microlife WatchBP O3 and Omron RS6 readings differing from the mercury standard by more than 5, 10, and 15 mmHg failed to fulfill the ESH-IP revision 2010 requirements in obese subjects. Therefore, the two devices cannot be recommended for use in obese subjects.

Do we need to evaluate diastolic blood pressure in patients with suspected orthostatic hypotension?

PURPOSE

The contribution of diastolic blood pressure measurement to the diagnosis of classical orthostatic hypotension is not known. We aimed to explore the prevalence of isolated systolic and diastolic orthostatic hypotension components in patients with syncope and orthostatic intolerance.

METHODS

A total of 1520 patients aged >15 years with suspected syncope and/or symptoms of orthostatic intolerance were investigated in a tertiary center using tilt-table testing and continuous non-invasive blood pressure monitoring. Classical orthostatic hypotension was defined as a decline in systolic blood pressure ≥20 mmHg and/or diastolic blood pressure ≥10 mmHg at 3 min of tilt test. The prevalence of upright systolic blood pressure <90 mmHg and its overlap with isolated diastolic orthostatic hypotension was also assessed.

RESULTS

One hundred eighty-six patients (12.2%) met current diagnostic criteria for classical orthostatic hypotension. Of these, 176 patients (94.6%) met the systolic criterion and 102 patients (54.8%) met the diastolic criterion. Ninety-two patients (49.5%) met both systolic and diastolic criteria, whereas ten patients (5.4%) met the diastolic criterion alone. Of these, three had systolic blood pressure <90 mmHg during tilt test and were diagnosed with orthostatic hypotension on the grounds of low standing blood pressure. Based on patient history and ancillary test results, causes of orthostatic intolerance and syncope other than orthostatic hypotension were present in the remaining seven patients.

CONCLUSIONS

An abnormal orthostatic fall in diastolic blood pressure without an abnormal fall in systolic blood pressure is rare among patients with syncope and orthostatic intolerance. Approximately 95% of patients with classical orthostatic hypotension can be identified by systolic criterion alone.

Worldwide trends in blood pressure from 1975 to 2015: a pooled analysis of 1479 population-based measurement studies with 19·1 million participants

BACKGROUND

Raised blood pressure is an important risk factor for cardiovascular diseases and chronic kidney disease. We estimated worldwide trends in mean systolic and mean diastolic blood pressure, and the prevalence of, and number of people with, raised blood pressure, defined as systolic blood pressure of 140 mm Hg or higher or diastolic blood pressure of 90 mm Hg or higher.

METHODS

For this analysis, we pooled national, subnational, or community population-based studies that had measured blood pressure in adults aged 18 years and older. We used a Bayesian hierarchical model to estimate trends from 1975 to 2015 in mean systolic and mean diastolic blood pressure, and the prevalence of raised blood pressure for 200 countries. We calculated the contributions of changes in prevalence versus population growth and ageing to the increase in the number of adults with raised blood pressure.

FINDINGS

We pooled 1479 studies that had measured the blood pressures of 19·1 million adults. Global age-standardised mean systolic blood pressure in 2015 was 127·0 mm Hg (95% credible interval 125·7-128·3) in men and 122·3 mm Hg (121·0-123·6) in women; age-standardised mean diastolic blood pressure was 78·7 mm Hg (77·9-79·5) for men and 76·7 mm Hg (75·9-77·6) for women. Global age-standardised prevalence of raised blood pressure was 24·1% (21·4-27·1) in men and 20·1% (17·8-22·5) in women in 2015. Mean systolic and mean diastolic blood pressure decreased substantially from 1975 to 2015 in high-income western and Asia Pacific countries, moving these countries from having some of the highest worldwide blood pressure in 1975 to the lowest in 2015. Mean blood pressure also decreased in women in central and eastern Europe, Latin America and the Caribbean, and, more recently, central Asia, Middle East, and north Africa, but the estimated trends in these super-regions had larger uncertainty than in high-income super-regions. By contrast, mean blood pressure might have increased in east and southeast Asia, south Asia, Oceania, and sub-Saharan Africa. In 2015, central and eastern Europe, sub-Saharan Africa, and south Asia had the highest blood pressure levels. Prevalence of raised blood pressure decreased in high-income and some middle-income countries; it remained unchanged elsewhere. The number of adults with raised blood pressure increased from 594 million in 1975 to 1·13 billion in 2015, with the increase largely in low-income and middle-income countries. The global increase in the number of adults with raised blood pressure is a net effect of increase due to population growth and ageing, and decrease due to declining age-specific prevalence.

INTERPRETATION

During the past four decades, the highest worldwide blood pressure levels have shifted from high-income countries to low-income countries in south Asia and sub-Saharan Africa due to opposite trends, while blood pressure has been persistently high in central and eastern Europe.

FUNDING

Wellcome Trust.

The efficacy of isometric resistance training utilizing handgrip exercise for blood pressure management: A randomized trial

INTRODUCTION

Hypertension is a major risk factor contributing to cardiovascular disease, which is the number one cause of deaths worldwide. Although antihypertensive medications are effective at controlling blood pressure, current first-line treatment for hypertension is nonpharmacological lifestyle modifications. Recent studies indicate that isometric resistance training (IRT) may also be effective for assisting with blood pressure management. The aim of this study was to determine the efficacy of IRT for blood pressure management and the suitability of a low-intensity working control group.

METHODS

Forty hypertensive individuals, aged between 36 and 65 years, conducted IRT for 8 weeks. Participants were randomized into 2 groups, working at an intensity of either 5% or 30% of their maximum voluntary contraction. Participants performed 4 × 2 minute isometric handgrip exercises with their nondominant hand, each separated by a 3-minute rest period, 3 days a week.

RESULTS

Blood pressure measurements were conducted at baseline and at the end of the protocol using a Finometer. Eight weeks of isometric resistance training resulted in a 7-mmHg reduction of resting systolic blood pressure (SBP) (136 ± 12 to 129 ± 15; P = 0.04) in the 30% group. Reductions of 4 mmHg were also seen in mean arterial pressure (MAP) (100 ± 8 to 96 ± 11; P = 0.04) in the 30% group. There were no statistically significant reductions in diastolic blood pressure for the 30% group, or any of the data for the 5% group.

CONCLUSION

Isometric resistance training conducted using handgrip exercise at 30% of maximum voluntary contraction significantly reduced SBP and MAP. A lack of reduction in blood pressure in the 5% group indicates that a low-intensity group may be suitable as a working control for future studies.

Montmorency Tart cherries (Prunus cerasus L.) modulate vascular function acutely, in the absence of improvement in cognitive performance

Cerebral blood volume and metabolism of oxygen decline as part of human ageing, and this has been previously shown to be related to cognitive decline. There is some evidence to suggest that polyphenol-rich foods can play an important role in delaying the onset or halting the progression of age-related health disorders such as CVD and Alzheimer's disease and to improve cognitive function. In the present study, an acute, placebo-controlled, double-blinded, cross-over, randomised Latin-square design study with a washout period of at least 14 d was conducted on twenty-seven, middle-aged (defined as 45-60 years) volunteers. Participants received either a 60 ml dose of Montmorency tart cherry concentrate (MC), which contained 68·0 (sd 0·26) mg cyanidin-3-glucoside/l, 160·75 (sd 0·55) mean gallic acid equivalent/l and 0·59 (sd 0·02) mean Trolox equivalent/l, respectively, or a placebo. Cerebrovascular responses, cognitive performance and blood pressure were assessed at baseline and 1, 2, 3 and 5 h following consumption. There were significant differences in concentrations of total Hb and oxygenated Hb during the task period 1 h after MC consumption (P≤0·05). Furthermore, MC consumption significantly lowered systolic blood pressure (P≤0·05) over a period of 3 h, with peak reductions of 6±2 mmHg at 1 h after MC consumption relative to the placebo. Cognitive function and mood were not affected. These results show that a single dose of MC concentrate can modulate certain variables of vascular function; however, this does not translate to improvements in cognition or mood.

Drug-induced blood pressure increase - recommendations for assessment in clinical and non-clinical studies

INTRODUCTION

Changes in blood pressure (BP) are now proactively examined throughout the drug development process as an integral aspect of safety monitoring. This is because hypertension is a very strong risk factor for cardiovascular events and drug-induced increases in BP have attracted increased regulatory attention. However, there is currently no guidance from regulatory agencies on the minimum BP data required for submissions, and there are no specific criteria for what constitutes a safety signal for increased BP in non clinical studies. Areas covered: Evaluation of BP increases through the drug discovery and development process. Expert opinion: Research into the effects of drugs should begin before clinical development is initiated and continue throughout the clinical trial program. Non clinical studies should inform a benefit-risk analysis that will aid decision-making of whether to enter the drug into Phase I development. The degree of acceptable risk will vary according to the therapy area, treatment indication and intended population for the new drug, and the approach to BP assessment and risk mitigation should be tailored accordingly. However, BP monitoring should always be included in clinical trials, and data collected from multiple studies, to convincingly prove or refute a suspicion of BP effects.

Change in Oxidative Stress of Normotensive Elderly Subjects Following Lifestyle Modifications

INTRODUCTION

Oxidative stress is associated with aging, which ultimately causes deterioration of muscles. Antioxidant defense system deteriorates while enhancing accumulations of Reactive Oxygen Species (ROS) due to lipid peroxidation and altered enzyme activities in old age. Regular practice of yoga can maintain the antioxidants level of the body, even in stressful conditions.

AIM

The present study was designed to assess the effects of lifestyle technique on oxidative stress and lipid profile in normotensive elderly subjects.

MATERIALS AND METHODS

Seventy four healthy elderly subjects (43 males and 31 females) 60 to 80 years of age were selected from the Santosh Medical College, Ghaziabad Uttar Pradesh, India, for three months lifestyle modification program which included morning walk, Nadi shodan pranayama, dietary restrictions and increased intake of water. Blood pressure and oxidative stress markers Glutathione (GSH), Super Oxide Dismutase (SOD) and Malondialdehyde (MDA) were recorded twice, one at baseline and another after three months of lifestyle modifications.

RESULTS

Post lifestyle modifications technique values revealed a significant increase in GSH (88.03±9.58 ng/ml vs 93.12±9.17 ng/ml, p < 0.0001) and SOD (78.22±11.97 ng/ml vs 85.22±11.08 ng/ml, p < 0.0001), and a decline in MDA (5.28±0.52 m mol/ml vs 4.48± 0.69 m mol/ml, p < 0.0001) levels. Further, there was significant reduction in the systolic blood pressure (p <0.0001) and diastolic blood pressure (p<0.0002); besides all fasting lipids decreased significantly except High Density Lipids (HDL).

CONCLUSION

The findings of the present study show that lifestyle modification is helpful in reducing cardiovascular disease risk but also assuring for good health by decreasing oxidative stress level along with lipid profile. Further, all these modifications are easy to follow. However, more studies are required to make a generalized lifestyle modification program in normotensive elderly subjects.

Neck circumference might predict gestational diabetes mellitus in Han Chinese women: A nested case-control study

AIMS/INTRODUCTION

A large neck circumference might be an indicator of metabolic syndrome and its components, and for certain patients is more practical as an index than waist circumference. The demarcation value for neck circumference that suggests metabolic syndrome appears to vary by ethnic group. Gestational diabetes mellitus is considered a component of metabolic syndrome in pregnant women. We investigated whether neck circumference in Han Chinese women is associated with gestational diabetes mellitus in early pregnancy, and determined a predictive demarcation value.

MATERIALS AND METHODS

A nested case-control study was carried out with 255 women aged 18-35 years. Gestational diabetes mellitus was diagnosed according to the criteria of the American Diabetes Association through a 2-h, 75-g oral glucose tolerance test.

RESULTS

Of the total population, 41 (16%) women developed gestational diabetes mellitus by 24-28 weeks of gestation. Neck circumference at gestational week 16 positively correlated with pre-pregnancy waist circumference, bodyweight and body mass index, and maternal age (P = 0.029) and hemoglobin A1c at gestational week 24 (P ≤ 0.001). By binary logistic regression, neck circumference was an independent predictor of gestational diabetes mellitus (odds ratio 1.840, 95% confidence interval 1.040-3.254; P = 0.036). According to the receiver operating characteristic curve, for predicting gestational diabetes mellitus the optimal demarcation for neck circumference at gestational week 16 was 35.15 cm.

CONCLUSIONS

Neck circumference is a viable tool to screen for gestational diabetes mellitus. In this population of pregnant Han Chinese women, a neck circumference of ≥35.15 cm was a predictor of gestational diabetes mellitus.

Automated Versus Manual Blood Pressure Measurement: A Randomized Crossover Trial in the Emergency Department of a Tertiary Care Hospital in Karachi, Pakistan: Are Third World Countries Ready for the Change?

BACKGROUND

Hypertension has proven to be a strong liability with 13.5% of all mortality worldwide being attributed to elevated blood pressures in 2001. An accurate blood pressure measurement lies at the crux of an appropriate diagnosis. Despite the mercury sphygmomanometer being the gold standard, the ongoing deliberation as to whether mercury sphygmomanometers should be replaced with the automated oscillometric devices stems from the risk mercury poses to the environment.

AIM

This study was performed to check the validity of automated oscillometric blood pressure measurements as compared to the manual blood pressure measurements in Karachi, Pakistan.

MATERIAL AND METHODS

Blood pressure was recorded in 200 individuals aged 15 and above using both, an automated oscillometric blood pressure device (Dinamap Procare 100) and a manual mercury sphygmomanometer concomitantly. Two nurses were assigned to each patient and the device, arm for taking the reading and nurses were randomly determined. SPSS version 20 was used for analysis. Mean and standard deviation of the systolic and diastolic measurements from each modality were compared to each other and P values of 0.05 or less were considered to be significant. Validation criteria of British Hypertension Society (BHS) and the US Association for the Advancement of Medical Instrumentation (AAMI) were used.

RESULTS

Two hundred patients were included. The mean of the difference of systolic was 8.54 ± 9.38 while the mean of the difference of diastolic was 4.21 ± 7.88. Patients were further divided into three groups of different systolic blood pressure <= 120, > 120 to = 150 and > 150, their means were 6.27 ± 8.39 (p-value 0.175), 8.91 ± 8.96 (p-value 0.004) and 10.98 ± 10.49 (p-value 0.001) respectively. In our study 89 patients were previously diagnosed with hypertension; their difference of mean systolic was 9.43 ± 9.89 (p-value 0.000) and difference of mean diastolic was 4.26 ± 7.35 (p-value 0.000).

CONCLUSIONS

Systolic readings from a previously validated device are not reliable when used in the ER and they show a higher degree of incongruency and inaccuracy when they are used outside validation settings. Also, readings from the right arm tend to be more precise.

Cerebral blood flow and autoregulation: current measurement techniques and prospects for noninvasive optical methods

Cerebral blood flow (CBF) and cerebral autoregulation (CA) are critically important to maintain proper brain perfusion and supply the brain with the necessary oxygen and energy substrates. Adequate brain perfusion is required to support normal brain function, to achieve successful aging, and to navigate acute and chronic medical conditions. We review the general principles of CBF measurements and the current techniques to measure CBF based on direct intravascular measurements, nuclear medicine, X-ray imaging, magnetic resonance imaging, ultrasound techniques, thermal diffusion, and optical methods. We also review techniques for arterial blood pressure measurements as well as theoretical and experimental methods for the assessment of CA, including recent approaches based on optical techniques. The assessment of cerebral perfusion in the clinical practice is also presented. The comprehensive description of principles, methods, and clinical requirements of CBF and CA measurements highlights the potentially important role that noninvasive optical methods can play in the assessment of neurovascular health. In fact, optical techniques have the ability to provide a noninvasive, quantitative, and continuous monitor of CBF and autoregulation.

Cuffless Blood Pressure Estimation Algorithms for Continuous Health-Care Monitoring

GOAL

Continuous blood pressure (BP) monitoring can provide invaluable information about individuals' health conditions. However, BP is conventionally measured using inconvenient cuff-based instruments, which prevents continuous BP monitoring. This paper presents an efficient algorithm, based on the pulse arrival time (PAT), for the continuous and cuffless estimation of the systolic BP, diastolic blood pressure (DBP), and mean arterial pressure (MAP) values.

METHODS

The proposed framework estimates the BP values through processing vital signals and extracting two types of features, which are based on either physiological parameters or whole-based representation of vital signals. Finally, the regression algorithms are employed for the BP estimation. Although the proposed algorithm works reliably without any need for calibration, an optional calibration procedure is also suggested, which can improve the system's accuracy even further.

RESULTS

The proposed method is evaluated on about a thousand subjects using the Association for the Advancement of Medical Instrumentation (AAMI) and the British Hypertension Society (BHS) standards. The method complies with the AAMI standard in the estimation of DBP and MAP values. Regarding the BHS protocol, the results achieve grade A for the estimation of DBP and grade B for the estimation of MAP.

CONCLUSION

We conclude that by using the PAT in combination with informative features from the vital signals, the BP can be accurately and reliably estimated in a noninvasive fashion.

SIGNIFICANCE

The results indicate that the proposed algorithm for the cuffless estimation of the BP can potentially enable mobile health-care gadgets to monitor the BP continuously.

How Accurate Are Home Blood Pressure Devices in Use? A Cross-Sectional Study

Background

Out of office blood pressure measurements, using either home monitors or 24 hour ambulatory monitoring, is widely recommended for management of hypertension. Though validation protocols, meant to be used by manufacturers, exist for blood pressure monitors, there is scant data in the literature about the accuracy of home blood pressure monitors in actual clinical practice. We performed a chart review in the blood pressure assessment clinic at a tertiary care centre.

Methods

We assessed the accuracy of home blood pressure monitors used by patients seen in the nephrology clinic in Ottawa between the years 2011 to 2014. We recorded patient demographics and clinical data, including the blood pressure measurements, arm circumference and the manufacturer of the home blood pressure monitor. The average of BP measurements performed with the home blood pressure monitor, were compared to those with the mercury sphygmomanometer. We defined accuracy based on a difference of 5 mm Hg in the blood pressure values between the home monitor and mercury sphygmomanometer readings. The two methods were compared using a Bland-Altman plot and a student’s t-test.

Results

The study included 210 patients. The mean age of the study population was 67 years and 61% was men. The average mid-arm circumference was 32.2 cms. 30% and 32% of the home BP monitors reported a mean systolic and diastolic BP values, respectively, different from the mercury measurements by 5 mm Hg or more. There was no significant difference between the monitors that were accurate versus those that were not when grouped according to the patient characteristics, cuff size or the brand of the home monitor.

Conclusions

An important proportion of home blood pressure monitors used by patients seen in our nephrology clinic were inaccurate. A re-validation of the accuracy and safety of the devices already in use is prudent before relying on these measurements for clinical decisions.

Orthostatic Hypotension and Risk of Venous Thromboembolism in 2 Cohort Studies

BACKGROUND

Although venous stasis is a risk factor for venous thromboembolism (VTE) and orthostatic hypotension (OH) can cause venous stasis, to our knowledge no study has examined the relationship between OH and VTE risk. We sought to quantify the association between OH and VTE (deep vein thrombosis or pulmonary embolism) using data from 2 large, prospective cohort studies: the Cardiovascular Health Study (CHS) and the Atherosclerosis Risk in Communities (ARIC) Study. We hypothesized that OH was positively associated with incident VTE.

METHODS

We measured OH-defined as a drop in systolic blood pressure (SBP) of at least 20 mm Hg or diastolic blood pressure (DBP) of at least 10 mm Hg within 3 minutes of standing-in participants aged 45-64 years in ARIC (n = 12,480) and ≥65 years in CHS (n = 5,027) at baseline visits (1987-1989 in ARIC; 1989-1990 and 1992-1993 in CHS), and followed participants for incident VTE (n = 568 in ARIC through 2011 and n = 148 in CHS through 2001). We calculated adjusted hazard ratios (HRs) and their 95% confidence intervals (CIs) for incident VTE in relation to OH status.

RESULTS

In CHS, there was a positive association between OH status and incident VTE (HR for VTE = 1.74 (95% CI: 1.20-2.51)). In contrast, there was no association between OH and VTE in the ARIC study (HR for VTE = 0.97 (95% CI: 0.70-1.33)).

CONCLUSIONS

Community-dwelling older adults with OH had a moderately increased risk of VTE. These results were not seen in a population-based middle-aged cohort.

The correlation between body mass index, limb circumferences and blood pressure cuff fit in bariatric surgical patients

Introduction:

The purpose of this study was to determine the correlation between body mass index (BMI) and upper and lower arm as well as lower leg circumferences and the frequency of correct blood pressure (BP) cuff fit. We explored recommendations for the most likely BP cuff size and location for the three BMI categories.

Materials and Methods:

Following IRB approval we retrospectively analyzed a research database of bariatric surgical patients with a BMI of ≥40 kg/m². Data included patients’ characteristics, upper and lower arm as well as lower leg circumferences. Patients were divided into three groups based on BMI (kg/m², Group I: <45, Group II: 45-55, and Group III: >55). Appropriate cuff fit using a standard or large adult BP cuff (CRITIKON^®, GE Healthcare, Waukesha, Wisconsin, USA) on the upper and lower arm, and lower leg was determined. We analyzed the percent proportion of proper cuff fit for cuff sizes and locations between groups using appropriate nonparametric testing.

Results:

Limb circumference correlated significantly with BMI (P = 0.01), and the upper arm correlated most closely (r = 0.76). A standard adult BP cuff on the lower arm fit properly in >90% and >80% and in Groups I and II, respectively. A large cuff on the lower arm was appropriate in 87% of Group III. In two participants, a large cuff fit properly on the lower leg.

Discussion:

Limb circumference significantly correlated with BMI. Recommendations for proper cuff fit in different BMI categories can be made.

Prevalence of pseudoresistant hypertension due to inaccurate blood pressure measurement

The prevalence of pseudoresistant hypertension (HTN) due to inaccurate BP measurement remains unknown. Triage BP measurements and measurements obtained at the same clinic visit by trained physicians were compared in consecutive adult patients referred for uncontrolled resistant HTN (RHTN). Triage BP measurements were taken by the clinic staff during normal intake procedures. BP measurements were obtained by trained physicians using the BpTRU (VSM Med Tech Ltd. Coquitlam, Canada) device. The prevalence of uncontrolled RHTN and differences in BP measurements were compared. Of 130 patients with uncontrolled RHTN, 33.1% (n = 43) were falsely identified as having uncontrolled RHTN based on triage BP measurements. The median (inter-quartile range) of differences in systolic BP between pseudoresistant and true resistant groups were 23 (17-33) mm Hg and 13 (6-21) mm Hg, respectively (P = .0001). The median (inter-quartile range) of differences in diastolic BP between the two groups were 12 (7-18) mm Hg and 8 (4-11) mm Hg, respectively (P = .001). Triage BP technique overestimated the prevalence of uncontrolled RHTN in approximately 33% of the patients emphasizing the importance of obtaining accurate BP measurements.

Development of a simulator for the validation of noninvasive blood pressure-monitoring devices

This research aimed to develop a simulator capable of oscillometric pressure pulses recorded from the participants for the validation of oscillometric noninvasive blood pressure (NIBP) devices. The simulator generates the pressure pulses to the cuff connected to NIBP devices depending on the oscillometric waveforms obtained from the participants. Device readings were compared with auscultatory references (systolic and diastolic blood pressures) of the participants. A total of 94 oscillometric waveforms from participants were used in the simulator for the validation of two automated NIBP devices (Omron HEM-7221 and UA-787Plus). For Omron HEM-7221, the differences between device readings and auscultation references for systolic and diastolic blood pressures were 2.82±7.27 and -4.74±6.73 mmHg, respectively. UA-787Plus showed differences of 3.26±5.69 and -3.53±6.61 mmHg, respectively. Although the number of individual measurements did not fulfill the ISO 81060-2 requirement for clinical validation, criterion 1, where the average of the difference and SD should be lower than ±5 and -8 mmHg, was fulfilled. Although the simulator still needs extensive comparative studies to be verified, it could be a potential candidate for a simple and robust tool for the validation and quality control of NIBP devices.

Noninvasive effects measurements for air pollution human studies: methods, analysis, and implications

Human exposure studies, compared with cell and animal models, are heavily relied upon to study the associations between health effects in humans and air pollutant inhalation. Human studies vary in exposure methodology, with some work conducted in controlled settings, whereas other studies are conducted in ambient environments. Human studies can also vary in the health metrics explored, as there exists a myriad of health effect end points commonly measured. In this review, we compiled mini reviews of the most commonly used noninvasive health effect end points that are suitable for panel studies of air pollution, broken into cardiovascular end points, respiratory end points, and biomarkers of effect from biological specimens. Pertinent information regarding each health end point and the suggested methods for mobile collection in the field are assessed. In addition, the clinical implications for each health end point are summarized, along with the factors identified that can modify each measurement. Finally, the important research findings regarding each health end point and air pollutant exposures were reviewed. It appeared that most of the adverse health effects end points explored were found to positively correlate with pollutant levels, although differences in study design, pollutants measured, and study population were found to influence the magnitude of these effects. Thus, this review is intended to act as a guide for researchers interested in conducting human exposure studies of air pollutants while in the field, although there can be a wider application for using these end points in many epidemiological study designs.

Blood pressure and the obese

With the prevalence of obesity escalating globally, an increasing number of patients who are obese are seeking elective or requiring emergency surgery. Certified registered nurse anesthetists are challenged to provide vigilant, safe care. The ability to provide supportive therapy and make anesthetic adjustments is often hindered with obesity. Although technological advancements may enhance patient care delivery, health care providers must question why and how specific tasks are performed. Health care providers should challenge themselves to acquire and evaluate current evidence that enables communication with colleagues, dissemination of findings to health care providers worldwide, and implementation of evidence-based practice.

Effect of sodium and potassium supplementation on vascular and endothelial function: a randomized controlled trial

BACKGROUND

It is known that increased potassium and reduced sodium intakes can improve postprandial endothelial function. However, the effect of increasing potassium in the presence of high sodium in the postprandial state is not known.

OBJECTIVE

We aimed to determine the effect of high potassium and high sodium on postprandial endothelial function as assessed by using flow-mediated dilatation (FMD) and arterial compliance as assessed by using pulse wave velocity (PWV) and central augmentation index (AIx).

DESIGN

Thirty-nine healthy, normotensive volunteers [21 women and 18 men; mean ± SD age: 37 ± 15 y; BMI (in kg/m(2)): 23.0 ± 2.8] received a meal with 3 mmol K and 65 mmol Na (low-potassium, high-sodium meal (LKHN)], a meal with 38 mmol K and 65 mmol Na [high-potassium, high-sodium meal (HKHN)], and a control meal with 3 mmol K and 6 mmol Na (low-potassium, low-sodium meal) on 3 separate occasions in a randomized crossover trial. Brachial artery FMD, carotid-femoral PWV, central AIx, and blood pressure (BP) were measured while participants were fasting and at 30, 60, 90, and 120 min after meals.

RESULTS

Compared with the LKHN, the addition of potassium (HKHN) significantly attenuated the postmeal decrease in FMD (P-meal by time interaction < 0.05). FMD was significantly lower after the LKHN than after the HKHN at 30 min (P < 0.01). AIx decreased after all meals (P < 0.05). There were no significant differences in AIx, PWV, or BP between treatments over time.

CONCLUSION

The addition of potassium to a high-sodium meal attenuates the sodium-induced postmeal reduction in endothelial function as assessed by FMD. This trial was registered at http://www.anzctr.org.au/ as ACTRN12613000772741.

Noninvasive assessment of hemodynamics: a comparative analysis of fingertip pulse contour analysis and impedance cardiography

OBJECTIVE

Systemic hemodynamic assessment is useful for characterizing the underlying physiology of hypertension, selecting individualized treatment approaches, and understanding the underlying mechanisms of action of interventions. Invasive methods are not suitable for routine clinic or research use, and noninvasive methods such as impedance cardiography have technical and practical limitations. Fingertip pulse contour analysis using the Nexfin device is a novel alternative to noninvasive assessment of blood pressure and hemodynamics. Although both impedance cardiography and the Nexfin have been validated against invasive methods, the extent to which they are correlated with each other is unknown. This study is a comparative analysis of data simultaneously obtained by impedance cardiography and using the Nexfin device.

METHODS

As part of a larger clinical trial, 13 adults with type 2 diabetes completed cardiovascular reactivity testing on three occasions: at study baseline and after two 4-week dietary treatment periods. Blood pressure, hemodynamics, and heart rate variability were assessed at rest and during acute mental stress.

RESULTS

Blood pressure, heart rate, and heart rate variability data were significantly correlated between the two devices, but hemodynamic data (stroke volume, cardiac output, total peripheral resistance) were not significantly correlated. Both techniques detected treatment-related changes in blood pressure and total peripheral resistance, but significantly differed in the magnitude and/or direction of treatment effects.

CONCLUSION

We conclude that Nexfin is not an appropriate alternative to impedance cardiography for measurement of underlying hemodynamics in psychophysiological research, but may be useful for beat-to-beat monitoring of blood pressure and heart rate variability.

Predictors and risks of body fat profiles in young New Zealand European, Māori and Pacific women: study protocol for the women's EXPLORE study

BACKGROUND

Body mass index (BMI) (kg/m(2)) is used internationally to assess body mass or adiposity. However, BMI does not discriminate body fat content or distribution and may vary among ethnicities. Many women with normal BMI are considered healthy, but may have an unidentified "hidden fat" profile associated with higher metabolic disease risk. If only BMI is used to indicate healthy body size, it may fail to predict underlying risks of diseases of lifestyle among population subgroups with normal BMI and different adiposity levels or distributions. Higher body fat levels are often attributed to excessive dietary intake and/or inadequate physical activity. These environmental influences regulate genes and proteins that alter energy expenditure/storage. Micro ribonucleic acid (miRNAs) can influence these genes and proteins, are sensitive to diet and exercise and may influence the varied metabolic responses observed between individuals. The study aims are to investigate associations between different body fat profiles and metabolic disease risk; dietary and physical activity patterns as predictors of body fat profiles; and whether these risk factors are associated with the expression of microRNAs related to energy expenditure or fat storage in young New Zealand women. Given the rising prevalence of obesity globally, this research will address a unique gap of knowledge in obesity research.

METHODS/DESIGN

A cross-sectional design to investigate 675 NZ European, Māori, and Pacific women aged 16-45 years. Women are classified into three main body fat profiles (n = 225 per ethnicity; n = 75 per body fat profile): 1) normal BMI, normal body fat percentage (BF%); 2) normal BMI, high BF%; 3) high BMI, high BF%. Regional body composition, biomarkers of metabolic disease risk (i.e. fasting insulin, glucose, HbA1c, lipids), inflammation (i.e. IL-6, TNF-alpha, hs-CRP), associations between lifestyle factors (i.e. dietary intake, physical activity, taste perceptions) and microRNA expression will be investigated.

DISCUSSION

This research targets post-menarcheal, premenopausal women, potentially exhibiting lifestyle behaviours resulting in excess body fat affecting metabolic health. These behaviours may be characterised by specific patterns of microRNA expression that will be explored in terms of tailored solutions specific to body fat profile groups and ethnicities.

TRIAL REGISTRATION

ACTRN12613000714785.

Dietary predictors of arterial stiffness in a cohort with type 1 and type 2 diabetes

OBJECTIVE

To determine the dietary predictors of central blood pressure, augmentation index and pulse wave velocity (PWV) in subjects with type 1 and type 2 diabetes.

METHODS

Participants were diagnosed with type 1 or type 2 diabetes and had PWV and/or pulse wave analysis performed. Dietary intake was measured using the Dietary Questionnaire for Epidemiological Studies Version 2 Food Frequency Questionnaire. Serum lipid species and carotenoids were measured, using liquid chromatography electrospray ionization-tandem mass spectrometry and high performance liquid chromatography, as biomarkers of dairy and vegetable intake, respectively. Associations were determined using linear regression adjusted for potential confounders.

RESULTS

PWV (n = 95) was inversely associated with reduced fat dairy intake (β = -0.01; 95% CI -0.02, -0.01; p = 0 < 0.05) in particular yoghurt consumption (β = -0.04; 95% CI -0.09, -0.01; p = 0 < 0.05) after multivariate adjustment. Total vegetable consumption was negatively associated with PWV in the whole cohort after full adjustment (β = -0.04; 95% CI -0.07, -0.01; p < 0.05). Individual lipid species, particularly those containing 14:0, 15:0, 16:0, 17:0 and 17:1 fatty acids, known to be of ruminant origin, in lysophosphatidylcholine, cholesterol ester, diacylglycerol, phosphatidylcholine, sphingomyelin and triacylglycerol classes were positively associated with intake of full fat dairy, after adjustment for multiple comparisons. However, there was no association between serum lipid species and PWV. There were no dietary predictors of central blood pressure or augmentation index after multivariate adjustment.

CONCLUSION

In this cohort of subjects with diabetes reduced fat dairy intake and vegetable consumption were inversely associated with PWV. The lack of a relationship between serum lipid species and PWV suggests that the fatty acid composition of dairy may not explain the beneficial effect.

Effect of high potassium diet on endothelial function

BACKGROUND AND AIMS

Increased potassium intake is related to reduced blood pressure (BP) and reduced stroke rate. The effect of increased dietary potassium on endothelial function remains unknown. The aim was to determine the effect of increased dietary potassium from fruit and vegetables on endothelial function.

METHODS AND RESULTS

Thirty five healthy men and women (age 32 ± 12 y) successfully completed a randomised cross-over study of 2 × 6 day diets either high or low in potassium. Flow mediated dilatation (FMD), BP, pulse wave velocity (PWV), augmentation index (AI) and a fasting blood sample for analysis of Intercellular Adhesion Molecule-1 (ICAM-1), E-selectin, asymmetric dimethylarginine (ADMA) and endothelin-1 were taken on completion of each intervention. Dietary change was achieved by including bananas and potatoes in the high potassium and apples and rice/pasta in the low potassium diet. Dietary adherence was assessed using 6 day weighed food diaries and a 24 h urine sample. The difference in potassium excretion between the two diets was 48 ± 32 mmol/d (P = 0.000). Fasting FMD was significantly improved by 0.6% ± 1.5% following the high compared to the low potassium diet (P = 0.03). There were no significant differences in BP, PWV, AI, ICAM-1, ADMA or endothelin-1 between the interventions. There was a significant reduction in E-selectin following the high (Median = 5.96 ng/ml) vs the low potassium diet (Median = 6.24 ng/ml), z = -2.49, P = 0.013.

CONCLUSION

Increased dietary potassium from fruit and vegetables improves FMD within 1 week in healthy men and women but the mechanisms for this effect remain unclear.

CLINICAL TRIAL REGISTRY

ACTRN12612000822886.

Attitudes and beliefs of health risks associated with sodium intake in diabetes

BACKGROUND

  Despite good evidence that reducing sodium intake can reduce blood pressure (BP), salt intake in people with type 1 diabetes (T1DM) or type 2 diabetes (T2DM) remains high. The purpose of this study was to describe the knowledge and beliefs of health risks associated with a high salt diet in adults with diabetes.

METHODS

Men and women with T1DM (n = 27; age 38 ± 16 years) or T2DM (n = 124; age 60 ± 11 years) were recruited.

RESULTS

Nine (6.0%) respondents knew the correct maximum daily recommended upper limit for salt intake. Thirty-six (23.9%) participants were not concerned with the amount of salt in their diet. Most participants knew that a diet high in salt was related to high BP (88.1%) and stroke (78.1%) and that foods such as pizza (80.8%) and bacon (84.8%) were high in salt. Fewer than 30% of people knew that foods such as white bread, cheese and breakfast cereals are high in salt (white bread 28.5%, cheese 29.1%, breakfast cereals 19.9%) and 51.0% correctly ranked three different nutrition information panels based on the sodium content. Label reading and purchase of low salt products was used by 60-80% of the group. Estimated average 24 hour urinary sodium excretion was 169 ± 32 mmol/24 h in men and 115 ± 27 mmol/24 h in women.

CONCLUSION

Label reading and purchase of low salt products was used by the majority of the group but their salt excretion was still high. Men who used label reading had a lower salt intake. Other strategies to promote a lower sodium intake such as reducing sodium in staple foods such as bread need investigation.

Diagnosis, evaluation, and management of the hypertensive disorders of pregnancy

OBJECTIVE

This guideline summarizes the quality of the evidence to date and provides a reasonable approach to the diagnosis, evaluation and treatment of the hypertensive disorders of pregnancy (HDP).

EVIDENCE

The literature reviewed included the previous Society of Obstetricians and Gynaecologists of Canada (SOGC) HDP guidelines from 2008 and their reference lists, and an update from 2006. Medline, Cochrane Database of Systematic Reviews (CDSR), Cochrane Central Registry of Controlled Trials (CCRCT) and Database of Abstracts and Reviews of Effects (DARE) were searched for literature published between January 2006 and March 2012. Articles were restricted to those published in French or English. Recommendations were evaluated using the criteria of the Canadian Task Force on Preventive Health Care and GRADE.