Working for a company that develops blood
pressure monitoring devices and technologies, I deal with blood pressure on
some level every day. We make accurate and reliable blood pressure measurement our
business...literally. So, it only makes sense that we should care about
accurate blood pressure measurement from a fundamental perspective, which is
the inspiration for my first blog post.
As most readers probably know, the typical
method for blood pressure measurement has long been the manual auscultatory
technique with a mercury column or mechanical aneroid sphygmomanometer.
However, with the benefits that automated BP devices provide with a repeatable
standardized technique and removal of observer bias, there has been a shift
towards automated devices in clinical practice. As the American Heart
Association (AHA) states in their most recent recommendations for blood
pressure measurement, "there is a role for (automated) devices in office
use, both as a substitute for traditional (manual) readings and as supplements
to them." * However,
the AHA goes on to recommend that a properly maintained monitor for manual
measurement of blood pressure be available for routine office measurement.
Another observation the AHA makes is that
although the auscultatory method has been the standard for blood pressure
measurement for over 50 years, surveys indicate that physicians rarely follow
the well published guidelines for their use. * This
is where we feel it is important to remind all healthcare professionals of
best practices related to manual blood pressure measurement, so without further
ado...
Step 1 - Choose the right
equipment:
What you will need:
1. A quality stethoscope
2. An appropriately sized blood pressure cuff
3. A blood pressure measurement instrument such as an aneroid or mercury column sphygmomanometer or an automated device with a manual inflate mode.
What you will need:
1. A quality stethoscope
2. An appropriately sized blood pressure cuff
3. A blood pressure measurement instrument such as an aneroid or mercury column sphygmomanometer or an automated device with a manual inflate mode.
Step 2 - Prepare the patient: Make
sure the patient is relaxed by allowing 5 minutes to relax before the first
reading. The patient should sit upright with their upper arm
positioned so it is level with their heart and feet flat on the floor.
Remove excess clothing that might interfere with the BP cuff or constrict
blood flow in the arm. Be sure you and the patient refrain from talking during
the reading.
Step 3 - Choose the proper BP
cuff size: Most measurement errors occur by not taking the time to
choose the proper cuff size. Wrap the cuff around the patient's arm and use the
INDEX line to determine if the patient's arm circumference falls within the
RANGE area. Otherwise, choose the appropriate smaller or larger cuff.
Step 4 - Place the BP cuff on
the patient's arm: Palpate/locate the brachial artery
and position the BP cuff so that the ARTERY marker points to the brachial
artery. Wrap the BP cuff snugly around the arm.
Step 5 - Position the stethoscope: On
the same arm that you placed the BP cuff, palpate the arm at the antecubical
fossa (crease of the arm) to locate the strongest pulse sounds and place the
bell of the stethoscope over the brachial artery at this location.
Step 6 - Inflate the BP cuff: Begin
pumping the cuff bulb as you listen to the pulse sounds. When the BP cuff has
inflated enough to stop blood flow you should hear no sounds through the
stethoscope. The gauge should read 30 to 40 mmHg above the person's normal
BP reading. If this value is unknown you can inflate the cuff to 160 - 180
mmHg. (If pulse sounds are heard right away, inflate to a higher pressure.)
Step 7 - Slowly Deflate the BP
cuff: Begin deflation. The AHA recommends that the pressure
should fall at 2 - 3 mmHg per second, anything faster may likely result in
an inaccurate measurement. *
Step 8 - Listen for the
Systolic Reading: The first occurence of rhythmic
sounds heard as blood begins to flow through the artery is the
patient's systolic pressure. This may resemble a tapping noise at first.
Step 9 - Listen for the
Diastolic Reading: Continue to listen as the BP cuff
pressure drops and the sounds fade. Note the gauge reading when the rhythmic
sounds stop. This will be the diastolic reading.
Step 10 - Double Check for
Accuracy: The AHA recommends taking a reading with both arms and
averaging the readings. To check the pressure again for accuracy wait about
five minutes between readings. Typically, blood pressure is higher in the
mornings and lower in the evenings. If the blood
pressure reading is a concern or masked or white coat hypertension is
suspected, a 24 hour blood pressure study may be required to assess the
patient's overall blood pressure profile.
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