Proposal Report Draft:
Literature Review research
Below is a collection of medical devices article that related to the development of portable digital blood pressure monitor using micro-controller.
1. Sphygmomanometer
Among the many common tools used in a doctor’s office is one
which we’re all familiar with, but whose real name is little-known. That
device is the sphygmomanometer, which is used to measure blood pressure.
The sphygmomanometer has been in wide use since the early 20th century,
and consists of a cuff placed around the arm, as well as a device to
measure the pressure at which blood flows freely, and the pressure at
which blood flow is restricted.
When a sphygmomanometer is used,
the cuff is inflated, usually around the upper arm, and the pressure is
gradually released. A digital sphygmomanometer often operates at the
touch of a button, and the blood pressure data is displayed on a digital
screen. Many manual sphygmomanometers are also still in use, which
usually require a medical professional to operate correctly.
In a
manual device, the pressure is displayed as the height of a column of
mercury in a tube. As the cuff is manually inflated, the height of the
column increases, and then decreases as the pressure is released. While
the cuff deflates, the doctor usually listens with a stethoscope to the main artery of the arm.
When the flow of blood begins to flow again after being
stopped by the cuff, there begins to be a rushing or pounding sound that
the doctor is able to hear through the stethoscope. The pressure at
which this occurs is noted, and is called the systolic pressure. The
cuff is allowed to further deflate, and the pressure at which the sound
is no longer audible is also noted, and is called the diastolic pressure. These two values are the pair of numbers that are recognizable as a blood pressure value.
It is important that a person’s blood pressure be measured when he is
relaxed, otherwise the reading will be falsely elevated. Hormones such
as adrenaline can increase blood pressure dramatically by constricting blood vessels.
A person who has just been severely startled, for example, will have an
elevated blood pressure compared to someone who is watching television.
Accurate readings are essential to determine the health of the heart
and therefore the rest of the body.
The use of a manual sphygmomanometer, like many things in medicine,
takes some practice before you can consistently get correct readings.
For those with hypertension,
however, this may be a valuable skill, since it is important in that
case to measure your blood pressure frequently. Apart from the
convenience involved, some patients get nervous when their blood
pressure is taken by a doctor, sometimes referred to as lab coat
syndrome. This can throw off the reading, so being able to measure your
own blood pressure at home is not only convenient but also medically
relevant.
2. Oscillometric
A second type of noninvasive blood pressure measurement strategy, the
oscillometric method, also employs an occluding cuff. However, in
contrast to the auscultatory method, which relies on detection of
Korotkoff sounds, the oscillometric method operates by sensing the
magnitude of oscillations caused by the blood as it begins to flow again
into the limb.
Typically, very faint blood flow oscillations begin to be detected as
the air pressure in the cuff coincides with SBP. As air pressure is
slowly released from the occluding cuff, the amplitude of these
pulsatile oscillations increases to a point and then decreases as blood
flow to the limb normalizes. Although the oscillation with the greatest
amplitude has been shown to correspond reliably with mean arterial
pressure (Mauck et al., 1980), determinations of SBP, which are
associated with a marked increase in amplitude of oscillations, and DBP,
which are associated with the point at which oscillations level off,
are often less accurate when compared with auscultatory measures (Fowler
et al., 1991).
Therefore, while oscillometric methods tend to overestimate SBP and
underestimate DBP (Maheswaran et al., 1988; Manolio et al., 1988), they
can be useful for determining accurate estimates of mean arterial
pressure.
Larkin, K. T., and Zayfert, C.
Published with assistance from the foundation established in memory of Amasa Stone Mather of the Class of 1907, Yale College.
3. Wrist Blood Pressure Monitor
The
onset of new medical technology paved the way for a more modern and
convenient way to measure blood pressure. While the old way to measure
blood pressure was by using a cuff that goes on the upper left arm and
uses a stethoscope, the new method now is by way of attaching it to the
wrist and is known as the wrist blood pressure monitor. The
advantages of the wrist blood pressure monitor are that it is easier to
use and can fit in any wrist size regardless if the person is thin or
fat. The comparison between the two methods is now more focused
on the accuracy of the blood pressure readings of the person rather
than the size of the monitors.
The wrist blood pressure monitor
is effective if it is properly used. The exact directions and procedures
must be followed to get accurate results. The accuracy of this monitor
is somehow affected by the position of the body so extra care should be
observed when using this monitor. Doctors advise that the arm and wrist
should be at heart level to get an accurate reading. Because of this
required positioning of the arm and wrist, more wrist monitors are made
to adapt to this requirement to record blood pressure.
The convenience of taking blood pressure at home is another advantage of the wrist monitor.
You can instantly get a reading of your blood pressure. If you have
been trained and guided properly to the use of the wrist monitor, then
you would be confident enough to get the accurate reading of your blood
pressure. In cases that you are unsure, then it is wise to go to your
doctor so he can correctly supervise and check the accuracy of your
blood pressure reading.
However, there are some instances that
you cannot really validate the accuracy of your blood pressure so you
have no choice but to consult your doctor and have him validate it. The
use of the old traditional method is helpful in this case to double
check the accuracy of the results. These cases are very few and have not
affected the good effects of the wrist blood pressure monitors.
The
use of the wrist blood pressure monitor is widely accepted because it
has its good uses. It is an effective tool to measure accurate blood
pressure immediately especially during travel. Most monitors have a
memory recall to check any fluctuations in the readings. It even has a
system to monitor irregular heartbeat. It has been clinically validated
and has passed the rigid standards of safety and accuracy set by most
independent medical organizations.
Most people are now aware
that having a weak heart means taking more necessary precautions in food
intakes and exercise. Such is the use of the wrist blood pressure
monitor, it is like a security blanket that helps monitor blood pressure
based on the accuracy and the convenient way it was made to be.
4. Blood Pressure Monitors
Which type of blood pressure monitor is recommended to use at
home?
High Blood Pressure affects millions of people in the UK increasing
the risk of stroke, heart attack and heart failure.
- High blood
pressure usually has no symptoms.
- The only
way for you to know if you have normal, high or low blood pressure
is to have it measured
- You can measure
your blood pressure in your own home ideally with a reliable,
accurate blood pressure monitor.
- The information
below is intended to help you make an informed purchase should
you decide to buy a machine to use at home.
- These machines
are available to buy online at First
Aid Warehouse, Medisave and Amazon
Types of Machines
For ease of use machines can be fully automatic and measure blood
pressure correctly on the upper arm at heart level. The readings
are given on a digital display and can be stored in the monitor's
memory or printed out. There are many different types of machines
available however the standards of accuracy may vary. The information
on these pages will hopefully help you make an informed decision
on your purchase - which machines are best, where to buy them from
trusted online stores and how to use the blood pressure monitor
correctly.
Sometimes your blood pressure is raised when taken in a clinical
or medical environment, such as your doctor’s surgery. This
is called white coat hypertension
and can be caused by feeling anxious, or by being in a busy or noisy
environment. Blood pressure readings taken at home are often lower
than those taken at a doctor’s surgery, whether a doctor or
a nurse takes them. Readings taken away from the clinic are now
seen to give a more accurate picture of your normal blood pressure.
Research published in the British Medical Journal revealed that
people who monitor their blood pressure at home have better blood
pressure control. The paper, "Blood pressure control by home
monitoring.." shows clear evidence that patient involvement
in the monitoring of blood pressure brings better results than those
monitored solely at their surgery or clinic.
Recommended Blood Pressure Monitors
Staff taking general enquiries at the Blood Pressure Association became
aware that increasingly people are measuring their own blood pressure
at home, and are keen to know what machines are recommended. There
is a wide range of machines available to the public. If you are
considering buying a blood pressure monitor it is important that
you make an informed purchase, it is worth investigating the quality,
types and check prices before you buy a machine for home use.
Details of blood pressure monitors suitable for home use, compiled
by the British Hypertension Society (BHS) are available on their
Web site you may find it a useful guide when you buy a blood pressure
monitor. All of the monitors on this list are digital upper arm
monitors and have been through independent testing shown in research
to be accurate and are currently available.
