2. Aneroid sphygmomanometers (mechanical types with a dial) are in
common use; they may require calibration checks, unlike mercury
manometers. Aneroid sphygmomanometers are considered safer
than mercury sphygmomanometers, although inexpensive ones are
less accurate.A major cause of departure from calibration is
mechanical jarring. Aneroids mounted on walls or stands are not
susceptible to this particular problem.
3. • Mercury sphygmomanometers are considered the gold
standard. They show blood pressure by affecting the
height of a column of mercury, which does not require
recalibration.Because of their accuracy, they are often
used in clinical trials of drugs and in clinical evaluations
of high-risk patients, including pregnant women. A wall
mounted mercury sphygmomanometer is also known
as a Baumanometer
4. • Digital meters employ oscillometric measurements and
electronic calculations rather than auscultation. They may
use manual or automatic inflation, but both types are
electronic, easy to operate without training, and can be used
in noisy environments. They measure systolic and diastolic
pressures by oscillometric detection, employing either
deformable membranes that are measured using differential
capacitance, or differential piezoresistance, and they include
a microprocessor
5. • The stethoscope is an acoustic medical device for auscultation, or
listening to the internal sounds of an animal or human body. It
typically has a small disc-shaped resonator that is placed against the
skin, and one or two tubes connected to two earpieces. A
stethoscope can be used to listen to the sounds made by the heart,
lungs or intestines, as well as blood flow in arteries and veins. In
combination with a manual sphygmomanometer, it is commonly
used when measuring blood pressure.
