Tag: blood pressure

Categories : Cardiovascular DiseaseTags : 1 Comment

Commonly Used Arm Positions can Greatly Overestimate BP Readings

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A study led by Johns Hopkins Medicine researchers concludes that commonly used ways of positioning the patient’s arm during blood pressure (BP) screenings can substantially overestimate test results and may lead to a misdiagnosis of hypertension.

In a report on the study, published in JAMA Internal Medicine, investigators examined the effects of three different arm positions: an arm supported on a desk, arm supported on a lap, and an unsupported arm hanging at the patient’s side. Researchers found that lap support overestimated systolic pressure by nearly 4mmHg, and an unsupported arm hanging at the side overestimated systolic pressure by nearly 7mmHg.

The findings confirm that arm position makes a “huge difference” when it comes to an accurate blood pressure measurement, says Tammy Brady, MD, PhD, senior author of the study. And they underscore the importance of adhering to clinical guidelines calling for firm support on a desk or other surface when measuring blood pressure, the investigators add.

The latest clinical practice guidelines from the American Heart Association emphasise several key steps for an accurate measurement – including appropriate cuff size, back support, feet flat on the floor with legs uncrossed, and an appropriate arm position, in which the middle of an adjustable BP cuff is positioned at mid-heart level on an arm supported on a desk or table.

Despite these recommendations, the researchers say BP is too often measured with patients seated on an exam table without any, or inadequate, arm support. In some cases, a clinician holds the arm, or the patient holds an arm in their lap. In the new Johns Hopkins study, the researchers recruited 133 adult participants (78% Black, 52% female) between Aug. 9, 2022, and June 1, 2023. Study participants, who ranged from age 18 to 80, were sorted at random into one of six possible groups that differed by order of the three seated arm positions. Measurements were taken during a single visit between 9 a.m. and 6 p.m. Before BP measures were taken, all participants first emptied their bladders and then walked for two minutes to mimic a typical clinical scenario in which people walk into a clinic or office before screening takes place. They then underwent a five-minute, seated rest period with their backs and feet supported. Each person, wearing an upper arm BP cuff selected and sized based on their upper arm size, had three sets of triplicate measurements taken with a digital blood pressure device 30 seconds apart.

Upon completion of each set of three measurements, the cuff was removed, participants walked for two minutes and rested for five minutes. In the same visit, they then underwent a fourth set of triplicate measurements with their arm supported on a desk, a set used to account for well-known variations in BP readings. All of the measurements were conducted in a quiet and private space, and participants were asked not to talk to researchers or use their phones during the screening.

Researchers found that BP measurements obtained with arm positions frequently used in clinical practice – an arm on the lap or unsupported at the side – were markedly higher than those obtained when the arm was supported on a desk, the standard, recommended arm position. Supporting the arm on the lap overestimated systolic and diastolic BP by 3.9mmHg and 4.0mmHg, respectively. An unsupported arm at the side overestimated systolic by 6.5mmHg and diastolic by 4.4mmHg.

“If you are consistently measuring blood pressure with an unsupported arm, and that gives you an overestimated BP of 6.5mmHg, that’s a potential difference between a systolic BP of 123 and 130, or 133 and 140 – which is considered stage 2 hypertension,” says study author Sherry Liu, MHS, an epidemiology research coordinator at Johns Hopkins Bloomberg School of Public Health.

Investigators caution that their study results may only apply during screenings with automated BP devices, and may not apply to readings done with other BP devices.

However, Brady says, the findings suggest that clinicians need to pay better attention to best practice guidelines, and that patients “must advocate for themselves in the clinical setting and when measuring their BP at home.”

Source: Johns Hopkins Medicine

Categories : Cardiovascular Disease Medical Research & TechnologyTags :

A Cuffless Smartphone App that Can Measure Blood Pressure

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Researchers at the University of Pittsburgh are pioneering a new approach to blood pressure monitoring, using the devices we carry with us every day. Ramakrishna Mukkamala, professor of bioengineering at Pitt’s Swanson School of Engineering, is passionate about developing accessible blood pressure (BP) detection tools. Instead of designing a new medical device to monitor BP, Mukkamala decided to take advantage of the sensors readily available in smartphones and figure out how to detect blood pressure with them. 

“The most significant thing you can do to reduce your risk of cardiovascular disease is to lower high blood pressure through lifestyle changes, but in underserved populations, many people don’t have access to blood pressure cuffs, regular doctor’s appointments, or even know it’s a problem,” Mukkamala said. “But they do have smartphones.”

Mukkamala’s team harnessed tools already built into most smartphones, like motion-sensing accelerometers, front cameras, and touch sensors to build an Android smartphone application that can measure an individual’s pulse pressure. The user performs a hand-raising motion while holding the smartphone to make a measurement. The results of the project, published in Scientific Reports, demonstrate a promising new technology that could uniquely help reduce the burden of systolic hypertension globally, particularly in underserved populations. 

Designing blood pressure technology for a touchscreen 

Turning a smartphone into a monitoring device is no easy task, as Vishaal Dhamotharan, graduate student in the Cardiovascular Health Tech Laboratory, found out through multiple iterations of app development. Because smartphones don’t have force sensing tools, a crucial element of the project was figuring out how to replicate the effects of a traditional blood pressure exam using only a cell phone, which the team solved by using a familiar force – gravity.

“Because of gravity, there’s a hydrostatic pressure change in your thumb when you raise your hands up above your heart, and using the phone’s accelerometer, you’re able to convert that into the relative change in pressure.” Dhamotharan said. 

By pairing this hand-raising motion with guided thumb maneuvers on the smartphone, the team was able to calculate each participant’s pulse pressure, the difference between systolic and diastolic numbers. For example, an individual with a BP measurement of 120/80 has a pulse pressure of 40. For Sanjeev Shroff, collaborator and bioengineering department chair, this publication is a promising advancement for blood pressure measurement devices. 

“Development of a cuffless blood pressure measurement device that does not require any external calibration is the holy grail – such a device currently does not exist,” Shroff said. “The research work reported in this publication is an important step in the right direction, and is also encouraging for additional work aimed at obtaining systolic, diastolic, and mean pressures.”

Although pulse pressure isn’t typically used in cardiovascular disease monitoring, the study revealed its significance as a metric for detecting hypertension, according to Céderick Landry, assistant professor at the University of Sherbrooke and former postdoctoral researcher in the lab. 

“Guidelines typically require doctors to measure both systolic and diastolic blood pressure, and pulse pressure is just the difference between the two.” Landry said. “We showed that if you only have access to pulse pressure, it’s still very correlated with hypertension, so part of our challenge now is changing the mentality on how to best measure things.”

Hypertension management within reach

This app could bring blood pressure monitoring software to any smartphone owner, enabling consistent self-monitoring and easy sharing of results with healthcare providers. This innovation is especially promising for managing hypertension, which can often be lowered through lifestyle changes such as reducing salt intake, quitting smoking and exercising regularly. 

“This app would be really useful in low-income settings where people may not even have existing access to blood pressure tools.” Dhamotharan said. “Being able to measure blood pressure more frequently would allow an individual to track any significant changes in blood pressure, monitor for hypertension, and be able to manage their conditions with that knowledge.” 

“The research is here – we just need some help making the technology better.” Landry said. “This is the first method of its kind, and even better, it’s something that we can start implementing right now.”

Source: University of Pittsburgh

Categories : Cardiovascular DiseaseTags :

Innovative Cuffless Blood Pressure Device Improves Hypertension Management

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A new study led by an investigator from Brigham and Women’s Hospital, evaluated a cuffless monitor that uses optical sensors to record blood pressure continually and efficiently, without disruption to the patient. The study, published in Frontiers in Medicine, highlights promising advancements in hypertension diagnosis, risk assessment and management that may be enabled by use of cuffless devices. 

“The successful management of hypertension depends on patients being able to take blood pressure measurements easily and reliably outside of the traditional doctor’s office setting,” said corresponding author Naomi Fisher, MD, of the Division of Endocrinology, Diabetes and Hypertension at Brigham and Women’s Hospital.  “Cuffless devices have the potential to revolutionise hypertension management.  They provide many more readings than traditional devices, during both the day and night, which can help confirm the diagnosis of hypertension and guide medication titration.” 

Medical guidelines increasingly recommend the incorporation of at-home blood pressure monitoring into hypertension diagnosis and management. This is because isolated blood pressure readings taken at a clinician’s office may be inaccurate: for some, blood pressure tends to rise in medical settings (“white coat hypertension”) while others have normal blood pressure during examination despite hypertensive readings at home (“masked hypertension”).  

Time-in-target-range (TTR) describes how often a patient’s blood pressure is in the normal range, and it is emerging as a promising metric of cardiovascular risk. But TTR requires more frequent blood pressure readings that can feasibly be obtained by patients with traditional blood pressure cuffs, which can be inconvenient, burdensome and sometimes uncomfortable for patients.  

Fisher, who designed and led the study, collaborated with co-authors from Aktiia SA, a Swiss biotechnology company, to analyse over 2.2 million blood pressure readings from 5189 subjects in Europe and the U.K. who wore a cuffless wrist monitor manufactured by Aktiia. On average, the Aktiia device collected 29 readings per day, a substantial increase from the number of blood pressure readings patients typically take with home devices (guidelines recommend four per day, which is more than most patients measure). Over a 15-day period, the researchers obtained an average of 434 readings from each patient.  

By calculating TTR over a 15-day period, the researchers were able to risk stratify participants by percentage of readings in target range and compare these classifications to those generated via traditional measurement patterns, using either 24-hour or week-long daytime monitoring schedules. They found that the traditional methods misclassified 26 and 45 percent of subjects, respectively, compared to the reference TTR. They determined that continual monitoring for seven days is required to obtain 90 percent or greater accuracy in hypertension risk classification, a frequency of measurement that may only be possible with cuffless monitors.  

Though the cuffless device studied here has not been approved by the US Food and Drug Administration, it has been validated in multiple studies and is available for over-the-counter purchase in Europe and the UK. Work to evaluate and set standards for such devices in the U.S. is ongoing. 

“For the first time, by using a cuffless device, we can collect continual out-of-office blood pressure readings and use these data to calculate a new metric, time-in-target-range, which shows great promise as a predictor of risk,” Fisher said. “The use of cuffless devices could create a shift in the paradigm of blood pressure monitoring and hypertension management.” 

Source: Brigham and Women’s Hospital

Categories : Medical Research & TechnologyTags :

A New Way to Measure Blood Pressure: A Digital Camera

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Male doctor with smartphone
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Engineers have designed a system that can remotely measure blood pressure from video of a person’s forehead and using artificial intelligence algorithms to extracting cardiac signals across a range of skin tones. They describe their new technology in a new paper published in Inventions.

Using the same remote-health technology they pioneered for non-contact monitoring of vital health signs, this new technology could replace the existing uncomfortable and cumbersome method of strapping an inflatable cuff to a patient’s arm or wrist, the researchers claim.

The researchers, from the University of South Australia and Baghdad’s Middle Technical University, describe the technique, which involves filming a person from a short distance for 10 seconds and then using AI to extract cardiac signals from two regions in the forehead.

Experiments were performed on 25 people with different skin tones and under changing light conditions, overcoming the limitations reported in previous studies. Compared to a digital sphygmomanometer (itself subject to errors), the systolic and diastolic readings were around 90% accurate.

“Monitoring blood pressure is essential to detect and manage cardiovascular diseases, the leading cause of global mortality, responsible for almost 18 million deaths in 2019,” says UniSA remote sensing engineer Professor Javaan Chahl. “Furthermore, in the past 30 years, the number of adults with hypertension has risen from 650 million to 1.28 billion worldwide.”

“The health sector needs a system that can accurately measure blood pressure and assess cardiovascular risks when physical contact with patients is unsafe or difficult, such as during the recent COVID outbreak,” Prof Chahl continues. “If we can perfect this technique, it will help manage one of the most serious health challenges facing the world today.”

The cutting-edge technology has come a long way since 2017, when the UniSA and Iraqi research team demonstrated image-processing algorithms that could extract a human’s heart rate from drone video.

In the past five years the researchers have developed algorithms to measure other vital signs, including breathing rates from 50 metres away, oxygen saturation, temperature, and jaundice in newborns.

Their non-contact technology was also deployed in the United States during the pandemic for non-contact monitoring of COVID signs.

Source: University of South Australia

Categories : Diet and Nutrition GenderTags :

Women Could Counteract Effects of Dietary Salt with Potassium

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By increasing the amount of potassium-rich foods in their diets, women could reduce the negative effects of salt, according to a study published today in European Heart Journal. However, this association was not observed in men.

“It is well known that high salt consumption is associated with elevated blood pressure and a raised risk of heart attacks and strokes,” said study author Professor Liffert Vogt of Amsterdam University Medical Centers, the Netherlands. “Health advice has focused on limiting salt intake but this is difficult to achieve when our diets include processed foods. Potassium helps the body excrete more sodium in the urine. In our study, dietary potassium was linked with the greatest health gains in women.”

The study included 11 267 male and 13 696 female participants of the EPIC-Norfolk study, which recruited 40 to 79 year-olds from general practices in Norfolk, UK, between 1993 and 1997. Participants completed a questionnaire on lifestyle habits, blood pressure was measured, and a urine sample was collected. Urinary sodium and potassium served as an estimate for dietary. Participants were divided into tertiles according to sodium intake (low/medium/high) and potassium intake (low/medium/high).

The researchers analysed the association between potassium intake and blood pressure after adjusting for age, sex and sodium intake. Potassium consumption (in grams per day) was associated with blood pressure in women — as intake went up, blood pressure went down. When the association was analysed according to sodium intake (low/medium/high), the relationship between potassium and blood pressure was only observed in women with high sodium intake, where every 1 gram increase in daily potassium was associated with a 2.4mmHg lower systolic blood pressure. In men, there was no association between potassium and blood pressure.

During a median follow-up of 19.5 years, 13 596 (55%) participants were hospitalised or died due to cardiovascular disease. The researchers analysed the association between potassium intake and cardiovascular events after adjusting for confounding factors. In the overall cohort, people in the highest tertile of potassium intake had a 13% lower risk of cardiovascular events compared to those in the lowest tertile. When men and women were analysed separately, the corresponding risk reductions were 7% and 11%, respectively. The amount of salt in the diet did not influence the relationship between potassium and cardiovascular events in men or women.

Professor Vogt said: “The results suggest that potassium helps preserve heart health, but that women benefit more than men. The relationship between potassium and cardiovascular events was the same regardless of salt intake, suggesting that potassium has other ways of protecting the heart on top of increasing sodium excretion.”

The WHO-recommened adult intake is at least 3.5 grams of potassium and less than 2 grams of sodium (5 grams of salt) per day. Foods rich in potassium include vegetables, fruit, nuts, beans, dairy products and fish.

Professor Vogt concluded: “Our findings indicate that a heart healthy diet goes beyond limiting salt to boosting potassium content. Food companies can help by swapping standard sodium-based salt for a potassium salt alternative in processed foods. On top of that, we should all prioritise fresh, unprocessed foods since they are both rich in potassium and low in salt.”

Source: European Society of Cardiology

Categories : Cardiovascular Disease Mental HealthTags :

Mental Health Conditions Disrupt Blood Pressure and Heart Rate

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A new study published in BioMedical Engineering has revealed that mental health is closely aligned to blood pressure and heart rate variations. The researchers found that mental illness could cause widely fluctuating blood pressure, which can lead to cardiovascular disease and organ damage.

University of South Australia researcher Dr Renly Lim and colleagues said there is clear evidence that mental illness interferes with the body’s autonomic functions, including blood pressure, heart rate, temperature and breathing.

“We reviewed 12 studies on people with anxiety, depression and panic disorders and found that, regardless of age, mental said is significantly associated with greater blood pressure variations during the day,” Dr Lim says.

“We also found that for people who are mentally ill, their heart rate does not adapt to external stressors as it should.

“Contrary to what many people think, a healthy heart is not one that beats like a metronome. Instead, it should adjust to withstand environmental and psychological challenges. A constantly changing heart rate is actually a sign of good health.”

Reduced heart rate variation (HRV) is common in people with mental illness and indicates that the body’s stress response is poor, exacerbating the negative effects of chronic stress.

Unlike normally consistent heart rates, HRV is more complex and is the time between two heartbeats, which should change according to external stressors.

“What we aim for is not a constantly changing heart rate but a high heart rate variation. This is achieved through a healthy diet, exercise, low stress and good mental health.”

Low HRV occurs during ‘fight-or-flight’ mode, or in those who are easily stressed and is common in people with chronic diseases, including cardiovascular and mental health problems.

While large blood pressure variations (BPV) during the day are not ideal, at night the systolic pressure should dip by between 10–20% to allow the heart to rest. People with mental health issues were found to have an insufficient BP drop at night, dropping less than 10%.

The reduced dipping can be caused by many factors, including autonomic dysfunction, poor quality of sleep and disrupted circadian rhythms that regulate the sleep-wake cycle.

“The takeout from this study is that we need to pay more attention to the physical impacts of mental illness,” Dr Lim said.

“It is a major global burden, affecting between 11–18 per cent (one billion) of people worldwide. Since mental illness can contribute to the deterioration of heart and blood pressure regulation, early therapeutic intervention is essential.”

Source: University of South Australia

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Doctor’s Presence During BP Measurement Triggers Flight-or-fight Response

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A small study has shown that a doctor’s presence during a blood pressure measurement skews the results, according to researchers who studied the effect by measuring nerve activity.

The phenomenon known as ‘white coat hypertension‘ is where the mere presence of a medical professional can raise blood pressure. Known about for decades, it occurs in about a third of patients.

In a small study published in the journal Hypertension, researchers probed the effect by measuring blood pressure, heart rate and nerve traffic in the skin and muscles with and without a doctor present.

The researchers found a “drastic reduction” in the body’s alarm response when a doctor was not present, said co-lead author Dr Guido Grassi, professor of internal medicine at the University of Milano-Bicocca.

Blood pressure and heart rate increases in response to a perceived threat, said Dr Meena Madhur, associate professor of medicine in the divisions of clinical pharmacology and cardiology at Vanderbilt University.

“If you’re out in the wild and a bear was charging after you, you’d want your blood vessels in your skin, for example, to constrict and the blood vessels in your muscles to dilate to provide more blood flow to those organs so that you can run really fast,” said Prof Madhur, who was not involved in the new research.

The study included 18 people, 14 of them men, with untreated mild to moderate hypertension. Each participant was examined in a lab, where an electrode measured nerve activity in the skin and muscles. Readings were taken twice in the presence of a doctor and twice without.

Both blood pressure and heart rate rose when the doctor was present, with nerve traffic patterns to the skin and skeletal muscle suggesting a classic fight or flight reaction.

Without the doctor’s presence, cardiovascular and neural responses were “strikingly different,” the researchers wrote. Fight or flight response indications were “entirely absent”.

Peak systolic blood pressure was an average of 14 points lower when the participant was alone than when a doctor was present, and peak heart rate was lowered by nearly 11 beats per minute.

This was the first study to actually measure sympathetic nervous system responses to doctors supervising a blood pressure measurement, the researchers wrote.

The study’s findings illustrated the complexity of blood pressure measurement and how it is affected by involuntary nervous system reactions, Grassi said. “Measurements without the doctor’s presence may better reflect true blood pressure values.”

White coat hypertension is not a new concept, Prof Madhur said, “this just drives home the fact that we should be more conscious of how the blood pressure is taken in the clinic.”

Last year, the American Medical Association and AHA issued a joint report endorsing more blood pressure measurement at home.

Limitations included the small study size due to the complexity of the measurements, the researchers said. Subsequent research would need to examine blood pressure medication as they could affect the fight or flight response, said Orof Madhur.

The work needs to be repeated with more women to examine possible sex differences. And she’d be interested in seeing whether people have the same response to nurses and other medical professionals as they did to doctors in this study.

Previous work shows that when nurses take blood pressure measurements, the white coat effect is reduced.

This latest research emphasises the need for people to handle blood pressure measurements with care, Prof Madhur said.

“I always tell my patients that we really can’t rely on a single office blood pressure measurement, because that’s just a random point in time,” she said.

Prof Madhur said that to take an accurate reading at home, a patient should sit still, with their back straight and supported and feet on the floor, waiting at least a few minutes before recording blood pressure. They should take multiple readings at the same time of day over the course of a week, and bring that log to their doctor’s appointment. Those at-home readings should be the ones used for planning treatment, she said.

“But,” Prof Madhur added, “if we are going to do an office blood pressure reading, it should be taken with the doctor not in the room.”

Source: American Heart Association

Categories : Medical Research & TechnologyTags :

Exact Location of Body’s Blood Pressure Sensors Finally Revealed

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After 60 years of fruitless searches by scientists, researchers from the University of Virginia have finally determined the location of our bodies’ natural blood-pressure sensors.

These cellular sensors monitor blood pressure and adjust hormone levels to keep it in check. Scientists have long suspected that these ‘baroreceptors’, may exist in or around specialised kidney cells called renin cells, but no one has been able to locate the baroreceptors within the cell until now.

The new findings, from UVA Health’s Dr Maria Luisa S Sequeira-Lopez and colleagues, finally reveal where the barometers are located, how they work and how they help prevent hypertension or hypotension. The study was published in Circulation Research.

“It was exhilarating to find that the elusive pressure-sensing mechanism, the baroreceptor, was intrinsic to the renin cell, which has the ability to sense and react, both within the same cell,” said Dr Sequeira-Lopez. “So the renin cells are sensors and responders.”

Back in 1957, it was first proposed that a pressure sensor existed inside renin cells because the cells had to know when to release renin, a hormone that helps regulate blood pressure. Though the baroreceptors had to exist, scientists couldn’t tell what it was and whether it was located in renin cells or surrounding cells.

To tackle this decades-old mystery, the study’s researchers used a combination of innovative lab models and determined that the baroreceptor was a ‘mechanotransducer’ inside renin cells. This mechanotransducer detects pressure changes outside the cell, then transmits these mechanical signals to the cell nucleus, akin to how the cochlea turns sound vibrations into nerve impulses.

Through in vitro tests, the researchers found that applying pressure to renin cells triggered changes within the cells and decreased activity of the renin gene, Ren1. The scientists also compared differences in gene activity in kidneys exposed to lower pressure and those exposed to higher pressure.

Ultimately, when the baroreceptors detect excess pressure outside the renin cell, renin production is cut back, while low blood pressure prompts more renin production.

Dr Sequeira-Lopez said she is looking forward to the work to “unravel the signaling and controlling mechanisms of this mechanotransducer and how we can use the information to develop therapies for hypertension.”

Source: University of Virginia