Philadelphia, PA - Higher diastolic blood pressure (DBP), but not systolic blood pressure (SBP), can impair cognitive status in individuals without a prior history of stroke or transient ischemic attack (TIA), according to results of a large study reported in the August 25, 2009 issue of Neurology [1].
"The present study indicates that elevated [DBP] levels are linearly and cross-sectionally associated with a higher likelihood of impaired cognitive status. If this association is causally established in future longitudinal studies, reducing elevated BP levels may result in reducing the incidence of dementia," lead author Dr Geogios Tsivgoulis (University of Alabama at Birmingham) said in an interview.
The study authors write that the prevalence of dementia is estimated at approximately 8% and the prevalence of hypertension is approximately 65% among individuals aged 65 years or older. While the relationship between blood pressure, cognitive function, and dementia has received a lot of attention in recent years, the findings have varied greatly.
In this study, the investigators sought to evaluate the cross-sectional relationship of blood-pressure components (SBP, DBP, and pulse pressure) with cognitive impairment after adjusting for potential confounders.
Tsivgoulis and his team looked at data from 19 836 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national, population-based, longitudinal cohort evaluating stroke risk.
The subset of patients studied by Tsivgoulis et al had no prior history of stroke or TIA and completed baseline home physical evaluations.
Intriguing findings
Study results showed that higher DBP levels were associated with impaired cognitive status after adjustment for demographic and environmental characteristics, risk factors, depressive symptoms, and antihypertensive medications. An increment of 10 mm Hg in DBP was associated with 7% (95% CI 1%-14%, p=0.0275) higher odds of cognitive impairment.
However, no independent association was identified between impaired cognitive status and SBP (odds ratio 1.02, 95% CI 0.99-1.06) or pulse pressure (OR 0.99, 95% CI 0.95-1.04).
"We attributed these intriguing findings to a potential association between diastolic hypertension and accelerated stiffening of cerebral small vessels that are profoundly affected by DBP," Tsivgoulis commented.
The results showed no evidence of nonlinear relationships between any of the blood-pressure components and impaired cognitive status; no interaction between age and the relationship of impaired cognitive status with SBP, DBP, or pulse pressure; and no interaction between race and the relationship of impaired cognitive status with SBP, DBP, or pulse-pressure levels.
"Our study showed that higher DBP levels were independently related to a higher likelihood of impaired cognitive status in a large national sample that was nearly balanced with respect to race and gender," said Tsivgoulis. However, he added, the linear, cross-sectional association needs to be confirmed in a longitudinal analysis.
Laying the groundwork
Dr John Hart (University of Texas, Dallas), who was not involved with the study, said that it "is another step in laying the groundwork for some things we're noticing about the vascular effects on cognitive decline with aging."
In the future, Hart said that he'd like to see a big, definitive, prospective, longitudinal study "with a rich set of cognitive measures and some neuroimaging to correlate with the findings.
"I think this study reaffirms the fact that you want to do your best to screen and treat for vascular risk factors in individuals, not just those that people normally think of [for heart disease], but also for strokes or vascular changes that might affect cognition in the brain. It just adds another piece of evidence that says that we should all be treating these risk factors aggressively to prevent long-term effects down the road. That's such a straightforward, easy thing to do, and it lets you see real differences at the end of the game."Philadelphia, PA - Higher diastolic blood pressure (DBP), but not systolic blood pressure (SBP), can impair cognitive status in individuals without a prior history of stroke or transient ischemic attack (TIA), according to results of a large study reported in the August 25, 2009 issue of Neurology [1].
"The present study indicates that elevated [DBP] levels are linearly and cross-sectionally associated with a higher likelihood of impaired cognitive status. If this association is causally established in future longitudinal studies, reducing elevated BP levels may result in reducing the incidence of dementia," lead author Dr Geogios Tsivgoulis (University of Alabama at Birmingham) said in an interview.
The study authors write that the prevalence of dementia is estimated at approximately 8% and the prevalence of hypertension is approximately 65% among individuals aged 65 years or older. While the relationship between blood pressure, cognitive function, and dementia has received a lot of attention in recent years, the findings have varied greatly.
In this study, the investigators sought to evaluate the cross-sectional relationship of blood-pressure components (SBP, DBP, and pulse pressure) with cognitive impairment after adjusting for potential confounders.
Tsivgoulis and his team looked at data from 19 836 participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national, population-based, longitudinal cohort evaluating stroke risk.
The subset of patients studied by Tsivgoulis et al had no prior history of stroke or TIA and completed baseline home physical evaluations.
Intriguing findings
Study results showed that higher DBP levels were associated with impaired cognitive status after adjustment for demographic and environmental characteristics, risk factors, depressive symptoms, and antihypertensive medications. An increment of 10 mm Hg in DBP was associated with 7% (95% CI 1%-14%, p=0.0275) higher odds of cognitive impairment.
However, no independent association was identified between impaired cognitive status and SBP (odds ratio 1.02, 95% CI 0.99-1.06) or pulse pressure (OR 0.99, 95% CI 0.95-1.04).
"We attributed these intriguing findings to a potential association between diastolic hypertension and accelerated stiffening of cerebral small vessels that are profoundly affected by DBP," Tsivgoulis commented.
The results showed no evidence of nonlinear relationships between any of the blood-pressure components and impaired cognitive status; no interaction between age and the relationship of impaired cognitive status with SBP, DBP, or pulse pressure; and no interaction between race and the relationship of impaired cognitive status with SBP, DBP, or pulse-pressure levels.
"Our study showed that higher DBP levels were independently related to a higher likelihood of impaired cognitive status in a large national sample that was nearly balanced with respect to race and gender," said Tsivgoulis. However, he added, the linear, cross-sectional association needs to be confirmed in a longitudinal analysis.
Laying the groundwork
Dr John Hart (University of Texas, Dallas), who was not involved with the study, said that it "is another step in laying the groundwork for some things we're noticing about the vascular effects on cognitive decline with aging."
In the future, Hart said that he'd like to see a big, definitive, prospective, longitudinal study "with a rich set of cognitive measures and some neuroimaging to correlate with the findings.
"I think this study reaffirms the fact that you want to do your best to screen and treat for vascular risk factors in individuals, not just those that people normally think of [for heart disease], but also for strokes or vascular changes that might affect cognition in the brain. It just adds another piece of evidence that says that we should all be treating these risk factors aggressively to prevent long-term effects down the road. That's such a straightforward, easy thing to do, and it lets you see real differences at the end of the game."
Friday, August 28, 2009
t+ blood pressure lite enables monitoring of patients' blood pressure at home
Oxford University spin-out t+ Medical has launched t+ blood pressure lite, which enables healthcare professionals to effectively monitor their patients’ blood pressure without patients having to leave their home.
t+ blood pressure lite enables healthcare professionals to monitor their patients' blood pressure without the inconvenience of having to visit the surgery each time.
GP Dan Lasserson from Jericho Health Centre, Oxford said: “Improving our diagnosis and management of hypertension is key to reducing the burden of cardiovascular disease. The BP lite system will allow us to make decisions much more accurately and it is more convenient for patients. Embracing new technology is essential for modern primary care so that we can work together with our patients to prevent the major diseases that cause disability and shorten life expectancy.”
The system has already been trialed, and is continuing to be used by the Stroke Prevention Research Unit at the John Radcliffe Hospital, Oxford. It was found that home monitoring of patients' blood pressure using t+ blood pressure lite was feasible in most patients following a mini-stroke (TIA), irrespective of age, and patient satisfaction was high. The home monitoring was able to identify masked hypertension and led to improved blood pressure control.
Business Development Director at t+ Medical Rob Halhead said: “t+ blood pressure lite is another example of our innovation. Our purpose is to use everyday technology which is familiar, cost effective and easy for patients to use to enable the NHS to deliver radically improved healthcare outcomes and at significantly lower cost. We take a collaborative approach with us wherever we go and we’re delighted with the improvements we’re helping our NHS colleagues to deliver in Oxfordshire”.
t+ blood pressure lite enables healthcare professionals to monitor their patients' blood pressure without the inconvenience of having to visit the surgery each time.
GP Dan Lasserson from Jericho Health Centre, Oxford said: “Improving our diagnosis and management of hypertension is key to reducing the burden of cardiovascular disease. The BP lite system will allow us to make decisions much more accurately and it is more convenient for patients. Embracing new technology is essential for modern primary care so that we can work together with our patients to prevent the major diseases that cause disability and shorten life expectancy.”
The system has already been trialed, and is continuing to be used by the Stroke Prevention Research Unit at the John Radcliffe Hospital, Oxford. It was found that home monitoring of patients' blood pressure using t+ blood pressure lite was feasible in most patients following a mini-stroke (TIA), irrespective of age, and patient satisfaction was high. The home monitoring was able to identify masked hypertension and led to improved blood pressure control.
Business Development Director at t+ Medical Rob Halhead said: “t+ blood pressure lite is another example of our innovation. Our purpose is to use everyday technology which is familiar, cost effective and easy for patients to use to enable the NHS to deliver radically improved healthcare outcomes and at significantly lower cost. We take a collaborative approach with us wherever we go and we’re delighted with the improvements we’re helping our NHS colleagues to deliver in Oxfordshire”.
Sunday, August 23, 2009
What are low blood pressure signs and symptoms?
When the blood pressure is not sufficient to deliver enough blood to the organs of the body, the organs do not work properly and may be permanently damaged. For example, if insufficient blood flows to the brain, brain cells do not receive enough oxygen and nutrients, and a person can feel lightheaded, dizzy, or even faint.
Going from a sitting or lying position to a standing position often brings out symptoms of low blood pressure. This occurs because standing causes blood to "settle" in the veins of the lower body, and this can lower the blood pressure. If the blood pressure is already low, standing can make the low pressure worse, to the point of causing symptoms. The development of lightheadedness, dizziness, or fainting upon standing caused by low blood pressure is called orthostatic hypotension. Normal individuals are able to compensate rapidly for the low pressure created by standing with the responses discussed previously and do not develop orthostatic hypotension.
When there is insufficient blood pressure to deliver blood to the coronary arteries (the arteries that supply blood to the heart's muscle), a person can develop chest pain (a symptom of angina) or even a heart attack.
When insufficient blood is delivered to the kidneys, the kidneys fail to eliminate wastes from the body, for example, urea and creatinine, and an increase in their levels in the blood occur (for example, elevations of blood urea nitrogen or BUN and serum creatinine, respectively).
Shock is a life-threatening condition where persistently low blood pressure causes organs such as kidney(s), liver, heart, lung, and brain to fail rapidly.
Going from a sitting or lying position to a standing position often brings out symptoms of low blood pressure. This occurs because standing causes blood to "settle" in the veins of the lower body, and this can lower the blood pressure. If the blood pressure is already low, standing can make the low pressure worse, to the point of causing symptoms. The development of lightheadedness, dizziness, or fainting upon standing caused by low blood pressure is called orthostatic hypotension. Normal individuals are able to compensate rapidly for the low pressure created by standing with the responses discussed previously and do not develop orthostatic hypotension.
When there is insufficient blood pressure to deliver blood to the coronary arteries (the arteries that supply blood to the heart's muscle), a person can develop chest pain (a symptom of angina) or even a heart attack.
When insufficient blood is delivered to the kidneys, the kidneys fail to eliminate wastes from the body, for example, urea and creatinine, and an increase in their levels in the blood occur (for example, elevations of blood urea nitrogen or BUN and serum creatinine, respectively).
Shock is a life-threatening condition where persistently low blood pressure causes organs such as kidney(s), liver, heart, lung, and brain to fail rapidly.
How does the body maintain normal blood pressure?
The body has mechanisms to alter or maintain blood pressure and blood flow. There are sensors that sense blood pressure in the walls of the arteries and send signals to the heart, the arterioles, the veins, and the kidneys that cause them to make changes that lower or increase blood pressure. There are several ways in which blood pressure can be adjusted - by adjusting the amount of blood pumped by the heart into the arteries (cardiac output), the amount of blood contained in the veins, the arteriolar resistance, and the volume of blood.
* The heart can speed up and contract more frequently and it can eject more blood with each contraction. Both of these responses increase the flow of blood into the arteries and increase blood pressure.
* The veins can expand and narrow. When veins expand, more blood can be stored in the veins and less blood returns to the heart for pumping into the arteries. As a result, the heart pumps less blood, and blood pressure is lower. On the other hand, when veins narrow, less blood is stored in the veins, more blood returns to the heart for pumping into the arteries, and blood pressure is higher.
* The arterioles can expand and narrow. Expanded arterioles create less resistance to the flow of blood and decrease blood pressure, while narrowed arterioles create more resistance and raise blood pressure.
* The kidney can respond to changes in blood pressure by increasing or decreasing the amount of urine that is produced. Urine is primarily water that is removed from the blood. When the kidney makes more urine, the amount (volume) of blood that fills the arteries and veins decreases, and this lowers blood pressure. If the kidneys make less urine, the amount of blood that fills the arteries and veins increases and this increases blood pressure. Compared with the other mechanisms for adjusting blood pressure, changes in the production of urine affect blood pressure slowly over hours and days. (The other mechanisms are effective in seconds.)
For example, low blood volume due to bleeding (such as a bleeding ulcer in your stomach or from a bad laceration from an injury) can cause low blood pressure. The body quickly responds to the low blood volume and pressure by the following adjustments which all increase blood pressure:
* The heart rate increases and the forcefulness of the heart's contractions increase, thus more blood is pumped through the heart.
* Veins narrow to return more blood to the heart for pumping.
* Blood flow to the kidneys decreases to reduce the formation of urine and thereby increases the volume of blood in the arteries and veins.
* Arterioles narrow to increase resistance to blood flow
These adaptive responses will keep the blood pressure in the normal range unless blood loss becomes so severe that the responses are overwhelmed.
* The heart can speed up and contract more frequently and it can eject more blood with each contraction. Both of these responses increase the flow of blood into the arteries and increase blood pressure.
* The veins can expand and narrow. When veins expand, more blood can be stored in the veins and less blood returns to the heart for pumping into the arteries. As a result, the heart pumps less blood, and blood pressure is lower. On the other hand, when veins narrow, less blood is stored in the veins, more blood returns to the heart for pumping into the arteries, and blood pressure is higher.
* The arterioles can expand and narrow. Expanded arterioles create less resistance to the flow of blood and decrease blood pressure, while narrowed arterioles create more resistance and raise blood pressure.
* The kidney can respond to changes in blood pressure by increasing or decreasing the amount of urine that is produced. Urine is primarily water that is removed from the blood. When the kidney makes more urine, the amount (volume) of blood that fills the arteries and veins decreases, and this lowers blood pressure. If the kidneys make less urine, the amount of blood that fills the arteries and veins increases and this increases blood pressure. Compared with the other mechanisms for adjusting blood pressure, changes in the production of urine affect blood pressure slowly over hours and days. (The other mechanisms are effective in seconds.)
For example, low blood volume due to bleeding (such as a bleeding ulcer in your stomach or from a bad laceration from an injury) can cause low blood pressure. The body quickly responds to the low blood volume and pressure by the following adjustments which all increase blood pressure:
* The heart rate increases and the forcefulness of the heart's contractions increase, thus more blood is pumped through the heart.
* Veins narrow to return more blood to the heart for pumping.
* Blood flow to the kidneys decreases to reduce the formation of urine and thereby increases the volume of blood in the arteries and veins.
* Arterioles narrow to increase resistance to blood flow
These adaptive responses will keep the blood pressure in the normal range unless blood loss becomes so severe that the responses are overwhelmed.
What is low blood pressure?
Blood pressure is the force exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs of life, which also include heart beat, rate of breathing, and temperature. Blood pressure is generated by the heart pumping blood into the arteries and is regulated by the response by the arteries to the flow of blood.
An individual's blood pressure is expressed as systolic/diastolic blood pressure, for example, 120/80.The systolic blood pressure (the top number) represents the pressure in the arteries as the muscle of the heart contracts and pumps blood into them. The diastolic blood pressure (the bottom number) represents the pressure in the arteries as the muscle of the heart relaxes after it contracts. Blood pressure always is higher when the heart is pumping (squeezing) than when it is relaxing.
Systolic blood pressure for most healthy adults falls between 90 and 120 millimeters of mercury (mm Hg). Normal diastolic blood pressure falls between 60 and 80 mm Hg. Current guidelines define normal blood pressure as lower than 120/80. Blood pressures over 130/80 are considered high. High blood pressure increases the risk of developing.
Low blood pressure (hypotension) is pressure so low it causes symptoms or signs due to the low flow of blood through the arteries and veins. When the flow of blood is too low to deliver enough oxygen and nutrients to vital organs such as the brain, heart, and kidney, the organs do not function normally and may be permanently damaged.
Unlike high blood pressure, low blood pressure is defined primarily by signs and symptoms of low blood flow and not by a specific blood pressure number. Some individuals may have a blood pressure of 90/50 with no symptoms of low blood pressure and therefore do not have low blood pressure. However, others who normally have high blood pressure may develop symptoms of low blood pressure if their blood pressure drops to 100/60
An individual's blood pressure is expressed as systolic/diastolic blood pressure, for example, 120/80.The systolic blood pressure (the top number) represents the pressure in the arteries as the muscle of the heart contracts and pumps blood into them. The diastolic blood pressure (the bottom number) represents the pressure in the arteries as the muscle of the heart relaxes after it contracts. Blood pressure always is higher when the heart is pumping (squeezing) than when it is relaxing.
Systolic blood pressure for most healthy adults falls between 90 and 120 millimeters of mercury (mm Hg). Normal diastolic blood pressure falls between 60 and 80 mm Hg. Current guidelines define normal blood pressure as lower than 120/80. Blood pressures over 130/80 are considered high. High blood pressure increases the risk of developing.
Low blood pressure (hypotension) is pressure so low it causes symptoms or signs due to the low flow of blood through the arteries and veins. When the flow of blood is too low to deliver enough oxygen and nutrients to vital organs such as the brain, heart, and kidney, the organs do not function normally and may be permanently damaged.
Unlike high blood pressure, low blood pressure is defined primarily by signs and symptoms of low blood flow and not by a specific blood pressure number. Some individuals may have a blood pressure of 90/50 with no symptoms of low blood pressure and therefore do not have low blood pressure. However, others who normally have high blood pressure may develop symptoms of low blood pressure if their blood pressure drops to 100/60
Pacemaker for high blood pressure
BACKGROUND: One in three American adults has high blood pressure; one third of those with high blood pressure are unaware of it, according to the American Heart Association. There are no known symptoms, and the only way to know your blood pressure is to have it checked. High blood pressure is defined by a pressure 140/90 mm Hg or above and can lead to stroke, heart attack, heart failure or kidney failure.
RISK FACTORS: Although high blood pressure offers no symptoms, there are many risk factors associated with it. Uncontrollable risk factors include race, heredity and age. Blacks develop high blood pressure more than whites, often earlier and with more severity. More than 40 percent of African Americans have high blood pressure, according to the American Heart Association. High Blood pressure may run in the family, so if your parents or close blood relatives have it, you have a higher chance of developing it. People over 35 have the highest chance of development -- men most often between 35 and 55, and women after menopause.
There are many ways you can control your chances of developing high blood pressure. Keep a healthy body mass index. A BMI of 30 or higher identifies obesity and a higher risk for high blood pressure. Eating a diet high in salt or drinking too much alcohol can also increase the risk. Physical activity helps maintain a healthy blood pressure, while mental stress often raises blood pressure.
TREATMENT: The first step to lower blood pressure should always be a healthy lifestyle. Common drugs to lower blood pressure are diuretics, beta blockers, ACE inhibitors, angiotensin antagonists, calcium channel blockers, alpha blockers, nervous system blockers and vasodilators. Each has a unique function, and multiple medications are commonly taken daily.
RHEOS: A new drug-free treatment for hypertension is the Rheos system. The device jump starts the body's natural regulation system to reduce high blood pressure. Electrical pulses are sent to baroreceptors (nerves inside the carotid arteries of the neck) which send a signal to the brain, which is interpreted as a rise in blood pressure. After the brain is alerted, it sends instructions to other parts of the body, such as the vessels, heart or kidneys, to do whatever is needed to reduce the blood pressure level. The device is about the size of an iPod and is implanted below the collar bone along with two thin electrode wires. In addition, physicians keep an external device that they use to regulate electrical energy from the pulse generator to the wires.
RISK FACTORS: Although high blood pressure offers no symptoms, there are many risk factors associated with it. Uncontrollable risk factors include race, heredity and age. Blacks develop high blood pressure more than whites, often earlier and with more severity. More than 40 percent of African Americans have high blood pressure, according to the American Heart Association. High Blood pressure may run in the family, so if your parents or close blood relatives have it, you have a higher chance of developing it. People over 35 have the highest chance of development -- men most often between 35 and 55, and women after menopause.
There are many ways you can control your chances of developing high blood pressure. Keep a healthy body mass index. A BMI of 30 or higher identifies obesity and a higher risk for high blood pressure. Eating a diet high in salt or drinking too much alcohol can also increase the risk. Physical activity helps maintain a healthy blood pressure, while mental stress often raises blood pressure.
TREATMENT: The first step to lower blood pressure should always be a healthy lifestyle. Common drugs to lower blood pressure are diuretics, beta blockers, ACE inhibitors, angiotensin antagonists, calcium channel blockers, alpha blockers, nervous system blockers and vasodilators. Each has a unique function, and multiple medications are commonly taken daily.
RHEOS: A new drug-free treatment for hypertension is the Rheos system. The device jump starts the body's natural regulation system to reduce high blood pressure. Electrical pulses are sent to baroreceptors (nerves inside the carotid arteries of the neck) which send a signal to the brain, which is interpreted as a rise in blood pressure. After the brain is alerted, it sends instructions to other parts of the body, such as the vessels, heart or kidneys, to do whatever is needed to reduce the blood pressure level. The device is about the size of an iPod and is implanted below the collar bone along with two thin electrode wires. In addition, physicians keep an external device that they use to regulate electrical energy from the pulse generator to the wires.
Friday, August 21, 2009
Blood pressure pill could help treat multiple sclerosis
Professor Lawrence Stienman, a neurologist, believes the drug, which costs a fraction of the price of normal treatment for the degenerative disease, could slow down the relentless march of the condition by blocking the way it attacks the central nervous system.
The research could offer new hope to the 100,000 or so sufferers of the condition which leads to debilitating attacks, including balance problems, bladder complaints and memory loss.
Professor Stienman, who studies treatments for MS, discovered that the pill Lisinopril may be effective in treating the condition when he was prescribed it for his own high blood pressure. He looked up the treatment during an internet search on his computer and found surprising links with his own research.
Further testing on mice and human brain tissue showed that it should in theory at least be affective in slowing down the progression of MS which damages myelin- a protective sheath surrounding nerve fibres of the central nervous system.
When myelin is damaged, this interferes with messages between the brain and other parts of the body.
While Professor Steinman of Stanford University, cautioned that extensive clinical trial work is needed to determine if the drug can do in humans what it does in mice, he is excited that "we were able to show that all the targets for lisinopril are there and ready for therapeutic manipulation in the multiple-sclerosis lesions of human patients.
The medication works by suppressing angiotensin, a hormone which controls blood pressure but also plays a role in MS. The hormone is found in elevated levels in the brains of MS sufferers.
The drug also appears to have certain anti-inflammatory properties which can also suppress MS.
The research, published in the journal of the Proceedings of the National Academy of Sciences, found in mice that Lisinopril reduced paralysis caused by MS and could even reverse the the damage..
Professor Steinman's results have major public-health implications, said Marc Feldmann, an Imperial College London immunologist who is familiar with the study but did not participate in it. He said that the current therapies for multiple sclerosis, including Tysabri, are expensive, costing thousands of pounds a year.
"If multiple-sclerosis patients can be treated with lisinopril at something like one per cent of the price of treatment with Tysabri, then far more patients will receive adequate therapy, at a substantially lower cost to those paying for it," he said.
Oscillometric methods
The auscultatory method uses a stethoscope and a sphygmomanometer. This comprises an inflatable (Riva-Rocci) cuff placed around the upper arm at roughly the same vertical height as the heart, attached to a mercury or aneroid manometer. The mercury manometer measures the height of a column of mercury, giving an absolute result without need for calibration, and consequently not subject to the errors and drift of calibration which affect other methods. The use of mercury manometers is often required in clinical trials and for the clinical measurement of hypertension in high risk patients, such as pregnant women.
A cuff of appropriate size is fitted smoothly and snugly, then inflated manually by repeatedly squeezing a rubber bulb until the artery is completely occluded. Listening with the stethoscope to the brachial artery at the elbow, the examiner slowly releases the pressure in the cuff. When blood just starts to flow in the artery, the turbulent flow creates a "whooshing" or pounding (first Korotkoff sound). The pressure at which this sound is first heard is the systolic blood pressure. The cuff pressure is further released until no sound can be heard (fifth Korotkoff sound), at the diastolic arterial pressure. Sometimes, the pressure is palpated (felt by hand) to get an estimate before auscultation.
Auscultatory methods
The auscultatory method uses a stethoscope and a sphygmomanometer. This comprises an inflatable (Riva-Rocci) cuff placed around the upper arm at roughly the same vertical height as the heart, attached to a mercury or aneroid manometer. The mercury manometer measures the height of a column of mercury, giving an absolute result without need for calibration, and consequently not subject to the errors and drift of calibration which affect other methods. The use of mercury manometers is often required in clinical trials and for the clinical measurement of hypertension in high risk patients, such as pregnant women.A cuff of appropriate size is fitted smoothly and snugly, then inflated manually by repeatedly squeezing a rubber bulb until the artery is completely occluded. Listening with the stethoscope to the brachial artery at the elbow, the examiner slowly releases the pressure in the cuff. When blood just starts to flow in the artery, the turbulent flow creates a "whooshing" or pounding (first Korotkoff sound). The pressure at which this sound is first heard is the systolic blood pressure. The cuff pressure is further released until no sound can be heard (fifth Korotkoff sound), at the diastolic arterial pressure. Sometimes, the pressure is palpated (felt by hand) to get an estimate before auscultation.
Palpation methods
A minimum systolic value can be roughly estimated without any equipment by palpation, most often used in emergency situations. Palpation of a radial pulse indicates a minimum blood pressure of 80 mmHg, a femoral pulse indicates at least 70 mmHg, and a carotid pulse indicates a minimum of 60 mmHg. However, one study indicated that this method was not accurate enough and often overestimated patients' systolic blood pressure.A more accurate value of systolic blood pressure can be obtained with a sphygmomanometer and palpating for when a radial pulse returns.The diastolic blood pressure can not be estimated by this method
Noninvasive measurement
The noninvasive auscultatory (from the Latin for listening) and oscillometric measurements are simpler and quicker than invasive measurements, require less expertise in fitting, have virtually no complications, and are less unpleasant and painful for the patient. However, non-invasive measures may yield somewhat lower accuracy and small systematic differences in numerical results. Non-invasive measurement methods are more commonly used for routine examinations and monitoring.
Measurement
Arterial pressure is most commonly measured via a sphygmomanometer, which historically used the height of a column of mercury to reflect the circulating pressure (see Noninvasive measurement). Today blood pressure values are still reported in millimetres of mercury (mmHg), though aneroid and electronic devices do not use mercury.
For each heartbeat, blood pressure varies between systolic and diastolic pressures. Systolic pressure is peak pressure in the arteries, which occurs near the end of the cardiac cycle when the ventricles are contracting. Diastolic pressure is minimum pressure in the arteries, which occurs near the beginning of the cardiac cycle when the ventricles are filled with blood. An example of normal measured values for a resting, healthy adult human is 115 mmHg systolic and 75 mmHg diastolic (written as 115/75 mmHg, and spoken [in the US] as "one fifteen over seventy-five"). Pulse pressure is the difference between systolic and diastolic pressures.
Systolic and diastolic arterial blood pressures are not static but undergo natural variations from one heartbeat to another and throughout the day (in a circadian rhythm). They also change in response to stress, nutritional factors, drugs, disease, exercise, and momentarily from standing up. Sometimes the variations are large. Hypertension refers to arterial pressure being abnormally high, as opposed to hypotension, when it is abnormally low. Along with body temperature and pulse rate, blood pressure measurements are the most commonly measured physiological parameters.
Arterial pressures can be measured invasively (by penetrating the skin and measuring inside the blood vessels) or non-invasively. The former is usually restricted to a hospital setting.
[edit] Units
The standard unit for blood pressure measurement is mmHg (millimeter of mercury). For example, normal pressure can be stated as 120 over 80, where 120 is the systolic reading and 80 is the diastolic.
For each heartbeat, blood pressure varies between systolic and diastolic pressures. Systolic pressure is peak pressure in the arteries, which occurs near the end of the cardiac cycle when the ventricles are contracting. Diastolic pressure is minimum pressure in the arteries, which occurs near the beginning of the cardiac cycle when the ventricles are filled with blood. An example of normal measured values for a resting, healthy adult human is 115 mmHg systolic and 75 mmHg diastolic (written as 115/75 mmHg, and spoken [in the US] as "one fifteen over seventy-five"). Pulse pressure is the difference between systolic and diastolic pressures.
Systolic and diastolic arterial blood pressures are not static but undergo natural variations from one heartbeat to another and throughout the day (in a circadian rhythm). They also change in response to stress, nutritional factors, drugs, disease, exercise, and momentarily from standing up. Sometimes the variations are large. Hypertension refers to arterial pressure being abnormally high, as opposed to hypotension, when it is abnormally low. Along with body temperature and pulse rate, blood pressure measurements are the most commonly measured physiological parameters.
Arterial pressures can be measured invasively (by penetrating the skin and measuring inside the blood vessels) or non-invasively. The former is usually restricted to a hospital setting.
[edit] Units
The standard unit for blood pressure measurement is mmHg (millimeter of mercury). For example, normal pressure can be stated as 120 over 80, where 120 is the systolic reading and 80 is the diastolic.
Blood pressure (BP)
Blood pressure (BP) is the pressure (force per unit area) exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as it moves away from the heart through arteries and capillaries, and toward the heart through veins. When unqualified, the term blood pressure usually refers to brachial arterial pressure: that is, in the major blood vessel of the upper left or right arm that takes blood away from the heart. Blood pressure may, however, sometimes be measured at other sites in the body, for instance at the ankle. The ratio of the blood pressure measured in the main artery at the ankle to the brachial blood pressure gives the Ankle Brachial Pressure Index (ABPI).
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