Measurement of blood pressure is an important part of vital sign measurement, identification of a patient's baseline status, and identification of changes in a patient's status (Taylor et al., 2023). Normal blood pressure is defined as a systolic pressure ;120 mm Hg and ;80 mm Hg (Whelton et al., 2018). Table 2-2 on page 77 identifies the categories for blood pressure levels in adults.

The auscultatory method has been the traditional approach to measurement of systolic and diastolic blood pressure and remains an acceptable method for measuring blood pressure (Muntner et al., 2019). This method is described below.

However, this method is being replaced more and more by oscillometric devices in clinical practice (Muntner et al., 2019). The use of an automated, electronic oscillometric blood pressure device to measure blood pressure is outlined in Skill 2-7 on page 76. Systolic blood pressure can also be estimated by palpation or using a Doppler ultrasound device (refer to the Skill Variation on page 93).

The nurse must know the appropriate equipment to use, including choosing the appropriate blood pressure cuff (see Table 2-3), how to accurately obtain the measurement, how to describe the sounds that are heard during the auscultatory method of measurement, and which site to choose to accurately assess blood pressure. Refer to Box 2-3 on page 78 for important considerations related to accurate blood pressure measurement.

A sphygmomanometer, along with a stethoscope, is used to assess blood pressure in the auscultatory method of blood pressure measurement. The sphygmomanometer consists of a cuff (with an air compartment), a pump, and the manometer (pressure dial) (Figure 1). The series of sounds for which to listen when assessing blood pressure using the auscultatory method are called Korotkoff sounds. Table 2-4 on page 86 describes and illustrates these sounds.

Regardless of the method used to measure blood pressure, health care providers must ensure the use of careful, accurate technique to avoid errors in BP measurement (Muntner et al., 2019; Pickering et al., 2005; Whelton et al., 2018). Box 2-4 on page 79 identifies potential sources of blood pressure measurement error.

Various sites can be used to assess blood pressure. The brachial artery and the popliteal artery are used most commonly. This skill discusses using the brachial artery site to obtain a blood pressure measurement. The skill begins with the procedure for estimating systolic pressure. Estimation of systolic pressure prevents inaccurate readings in the presence of an auscultatory gap (a pause in the auscultated sounds). To identify the first Korotkoff sound accurately, the cuff must be inflated 20 to 30 mm Hg above the point at which the pulse can no longer be felt (Muntner et al., 2019).

At times, it is necessary to assess a patient for orthostatic hypotension (postural hypotension). Assessment for orthostatic hypotension may be accomplished using either an automated, electronic oscillometric blood pressure device or the auscultatory method of measuring blood pressure. Box 2-5 on page 79 outlines the procedure to assess for orthostatic hypotension.

Assessment

Assess the brachial pulse, or the pulse appropriate for the site being used. Assess for an intravenous infusion or breast or axilla surgery on the side of the body corresponding to the arm used. Assess for the presence of a cast, arteriovenous shunt, or injured or diseased limb. If any of these conditions are present, do not use the affected arm to monitor blood pressure. Assess the size of the limb so that the appropriate-sized blood pressure cuff can be used (refer to Table 2-3). Assess for factors that could affect blood pressure reading, such as the patient's age, physical activity, weight, fluid balance, medications, and presence of disease and/or health conditions. Note baseline or previous blood pressure measurements. Assess the patient for pain. If the patient reports pain, give pain medication as ordered before assessing blood pressure. If the blood pressure is taken while the patient is in pain, make a notation concerning the pain if the blood pressure is elevated.

Actual or Potential Health Problems and Needs

Many actual or potential health problems or needs may require the use of this skill as part of related interventions. An appropriate health problem or need may include:

• Impaired Cardiac Output
• Hypertension risk
• Hypotension risk

Outcome Identification and Planning

The expected outcome to achieve when measuring blood pressure is that the patient's blood pressure is measured accurately without injury. Other outcomes may be appropriate, depending on the specific diagnosis or patient problem identified for the patient.

Implementation

Action	Rationale
1. Check the prescribed interventions or plan of care for frequency of blood pressure measurement. More frequent measurement may be appropriate based on nursing judgment.	Provides for patient safety.
2. Perform hand hygiene and put on PPE, if indicated.	Hand hygiene and PPE prevent the spread of microorganisms. PPE is required based on transmission precautions.
3. Identify the patient.	Identifying the patient ensures the right patient receives the intervention and helps prevent errors.
4. Close the curtains around the bed and close the door to the room, if possible. Discuss the procedure with the patient and assess patient's ability to assist with the procedure. Instruct the patient to hold the limb still and refrain from speaking during the measurement. Validate that the patient has relaxed for several minutes.	This ensures the patient's privacy. Explanation relieves anxiety and facilitates cooperation. Keeping the limb still and refraining from talking provide for accurate measurement of BP levels (Muntner et al., 2019). Activity immediately before measurement can result in inaccurate results.
5. Put on gloves, if indicated.	Gloves prevent contact with blood and body fluids. Gloves are usually not required for measurement of blood pressure, unless contact with blood or body fluids is anticipated.
6. Select the appropriate arm (or alternate site) for measurement and blood pressure cuff (refer to Table 2-3).	Decision on measurement site and cuff size is based on nurse's assessment of individual patient circumstances. Incorrect cuff size contributes to the most frequent error in measurement in nonacute care settings (Muntner et al., 2019).
7. Have the patient assume a comfortable lying or sitting position with the forearm supported at the level of the heart and the palm of the hand upward (Figure 2). If the measurement is taken in the supine position, support the arm with a pillow. In the sitting position, support the arm yourself or by using the bedside table. If the patient is sitting, have the patient sit back in the chair so that the chair supports their back. In addition, make sure the patient keeps the legs uncrossed.	The position of the arm can have a major influence when the blood pressure is measured; if the upper arm is below the level of the right atrium, the readings will be too high. If the arm is above the level of the heart, the readings will be too low (Muntner et al., 2019; Pickering et al., 2005). This position places the brachial artery on the inner aspect of the elbow so that the bell or diaphragm of the stethoscope can rest on it easily. Support for the patient's arm prevents isometric exercise that will affect the BP level (Muntner et al., 2019). If the back is not supported, the diastolic pressure may be elevated falsely; if the legs are crossed, the systolic pressure may be elevated falsely (Muntner et al., 2019; Pickering et al., 2005).
8. Expose the brachial artery by removing garments or move a sleeve if it is not too tight, above the area where the cuff will be placed.	Clothing over the artery interferes with the ability to hear sounds and can cause inaccurate blood pressure readings. A tight sleeve would cause congestion of blood and possibly inaccurate readings (Muntner et al., 2019).
9. Palpate the location of the brachial artery. Center the bladder of the cuff over the brachial artery, about midway on the upper arm, so that the lower edge of the cuff is about 2.5 to 5 cm (1 to 2 inches) above the inner aspect of the elbow. Line up the artery marking on the cuff with the patient's brachial artery. The tubing should extend from the edge of the cuff nearer the patient's elbow (Figure 3).	Pressure in the cuff applied directly to the artery provides the most accurate readings. If the cuff gets in the way of the stethoscope, readings are likely to be inaccurate. A cuff placed upside down with the tubing toward the patient's head may give a false reading.
10. Wrap the cuff around the arm smoothly and snugly, and fasten it. Do not allow any clothing to interfere with the proper placement of the cuff.	A smooth cuff and snug wrapping produce equal pressure and help promote an accurate measurement. A cuff wrapped too loosely results in an inaccurate reading.
11. Check that the needle on the aneroid gauge is within the zero mark (Figure 4).	If the needle is not in the zero area, the blood pressure reading may not be accurate.
Estimating Systolic Pressure
12. Palpate the pulse at the brachial or radial artery by pressing gently with the fingertips (Figure 5).	To identify the first Korotkoff sound accurately, the cuff must be inflated 20 to 30 mm Hg above the point at which the pulse can no longer be felt (Muntner et al., 2019).
13. Tighten the screw valve on the air pump.	The bladder within the cuff will not inflate with the valve open.
14. Inflate the cuff while continuing to palpate the artery. Note the point on the gauge where the pulse disappears.	The point where the pulse disappears provides an estimate of the systolic pressure. To identify the first Korotkoff sound accurately, the cuff must be inflated to a pressure above the point at which the pulse can no longer be felt.
15. Deflate the cuff and wait 1 minute.	Allowing a brief pause before continuing permits the blood to refill and circulate through the arm.
Obtaining Blood Pressure Measurement
16. Assume a position that is no more than 3 ft away from the gauge.	A distance of more than about 3 ft can interfere with accurate reading of the numbers on the gauge.
17. Place the stethoscope earpieces in your ears. Direct the earpieces forward into the canal and not against the ear itself.	Proper placement blocks extraneous noise and allows sound to travel more clearly.
18. Place the bell or diaphragm of the stethoscope firmly but with as little pressure as possible over the brachial artery (Figure 6). Do not allow the stethoscope to touch clothing or the cuff.	Having the bell or diaphragm directly over the artery allows more accurate readings. Heavy pressure on the brachial artery distorts the shape of the artery and the sound. Placing the bell or diaphragm away from clothing and the cuff prevents noise, which would distract from the sounds made by blood flowing through the artery.
19. Pump the pressure 20 to 30 mm Hg above the point at which the systolic pressure was palpated and estimated. Open the valve on the manometer and allow air to escape slowly (allowing the gauge to drop 2 mm Hg per second) (Muntner et al., 2019).	Increasing the pressure above the point where the pulse disappeared ensures a period before hearing the first sound that corresponds with the systolic pressure. It prevents misinterpreting phase II sounds as phase I sounds.
20. Note the point on the gauge at which the first of at least two consecutive beats appears (Figure 7). Read the pressure to the closest 2 mm Hg. Note this number as the systolic pressure.	Systolic pressure is the point at which the blood in the artery is first able to force its way through the vessel at a similar pressure exerted by the air bladder in the cuff. The first sound is phase I of Korotkoff sounds.
21. Do not reinflate the cuff once the air is being released to recheck the systolic pressure reading.	Reinflating the cuff while obtaining the blood pressure is uncomfortable for the patient and can cause an inaccurate reading. Reinflating the cuff causes congestion of blood in the lower arm, which lessens the loudness of Korotkoff sounds.
22. Note the point at which the sound completely disappears (Figure 8). Read the pressure to the closest 2 mm Hg. Note this number as the diastolic pressure.	The point at which the sound disappears corresponds to the beginning of phase V Korotkoff sounds and is generally considered the diastolic pressure reading (Muntner et al., 2019; Pickering et al., 2005).
23. Allow the remaining air to escape quickly. Repeat any suspicious reading, but wait at least 1 to 2 minutes. Deflate the cuff completely between attempts to check the blood pressure.	False readings are likely to occur if there is congestion of blood in the limb while obtaining repeated readings.
24. When measurement is completed, remove the cuff. Remove gloves, if worn. Perform hand hygiene. Cover the patient and help them to a position of comfort.	Removing gloves properly reduces the risk for infection transmission and contamination of other items. Hand hygiene prevents the spread of microorganisms. Covering and positioning the patient ensures patient comfort.
25. Clean the bell or diaphragm of the stethoscope with the alcohol wipe. Clean and store the sphygmomanometer, according to facility policy.	Appropriate cleaning deters the spread of microorganisms. Equipment should be left ready for use.
26. Remove additional PPE, if used. Perform hand hygiene.	Proper removal of PPE reduces the risk for infection transmission and contamination of other items. Hand hygiene deters the spread of microorganisms.

Evaluation

The expected outcome has been met when the blood pressure has been measured accurately without injury and with minimal patient discomfort.