*Skill 24-4 : Assessing Blood Pressure by Auscultation

Home Care Considerations

-Automated blood pressure devices in public locations are generally inaccurate and inconsistent. In addition, the cuffs on these devices are inadequate for persons with large arms (Pickering et al., 2004). -Explain to the patient that it is important to use a cuff size appropriate for limb circumference. Inform the patient that cuff sizes range from a pediatric cuff to a large thigh cuff and that a poorly fitting cuff can result in an inaccurate measurement. -Inform the patient about digital blood pressure monitoring equipment. Although more costly than manual cuffs, most provide an easy-to-read recording of systolic and diastolic measurements. -Explain that three readings, at least 1 minute apart, should be taken while in a sitting position, both in the morning and at night. Measurement should occur after resting quietly in a chair for 3 to 5 minutes, with the upper arm at heart level. The readings should be recorded to show to the health care provider. -Explain that home monitoring devices should be checked for accuracy every 1 to 2 years. Readings should be compared with auscultated measurement by a health care practitioner to ensure accuracy.

Infant and Child Considerations

-In infants and small children, the lower extremities are commonly used for blood pressure monitoring. The more common sites are the popliteal, dorsalis pedis, and posterior tibial. Blood pressures obtained in the lower extremities are generally higher than if taken in the upper extremities. In children over 1 year of age, the systolic pressure in the thigh tends to be 10 to 40 mm Hg higher than in the arm; the diastolic pressure remains the same (Kyle & Carman, 2013). -Infants and children presenting with cardiac complaints may have blood pressures assessed in all four extremities. Large differences among blood pressure readings can indicate heart defects. -The fifth Korotkoff sound corresponds to diastolic blood pressure in children. In some children, the Korotkoff sounds continue to 0 mm Hg. In this situation, document the reading as systolic pressure over "P" for pulse (Kyle & Carman, 2013).

SPECIAL CONSIDERATIONS General Considerations

-It is recommended that blood pressure measurements should be checked in both arms at the first examination. Most people have differences in blood pressure readings between arms. It is normal to have a 5- to 10-mm Hg difference in the systolic reading between arms. When there is a consistent interarm difference, use the arm with the higher pressure (Pickering et al., 2004). -If you have difficulty hearing the blood pressure sounds, raise the patient's arm, with cuff in place, over the patient's head for 30 seconds before rechecking the blood pressure. Inflate the cuff while the arm is elevated, and then gently lower the arm while continuing to support it. Position the stethoscope and deflate the cuff at the usual rate while listening for Korotkoff sounds. Raising the arm over the head reduces vascular volume in the limb and improves blood flow to enhance the Korotkoff sounds (Pickering et al., 2004). -Blood pressure can be assessed using an automatic electronic blood pressure monitor or Doppler ultrasound. -[Many versions of automatic electronic blood pressure monitors are not recommended for patients with irregular heart rates, tremors, or the inability to hold the extremity still. The presence of these conditions may cause the monitor to incorrectly overinflate the cuff, causing pain for the patient. Check the manufacturer's guidelines when considering use with these patients. -Diastolic pressure measured while the patient is sitting is approximately 5 mm Hg higher than when measured while the patient is supine; systolic pressure measured while the patient is supine is approximately 8 mm Hg higher than when measured in the patient who is sitting (Pickering et al., 2004). -Measuring blood pressure in the forearm by auscultating the radial artery for the Korotkoff sounds is becoming more common. Forearm measurements tend to be higher than the upper arm measurements (Domiano et al., 2008; Frese et al., 2011). The accuracy of readings with forearm monitors is affected by the position of the wrist relative to the heart. This can be avoided if the wrist is always at heart level when the reading is taken (Pickering et al., 2004). This site for measurement has been suggested as an alternative for obtaining blood pressure readings in people who are obese. It is often difficult to obtain the appropriately sized cuff for the upper arm, given arm circumference and conical-shaped upper arms common in obesity. The conical shape of the upper arm makes it difficult to fit the cuff to the arm, increasing the likelihood of inaccurate blood pressure measurement (Palatini & Parati, 2011). Thus, measurement in the forearm can be a possible solution to this problem. -When the patient's brachial artery is inaccessible and/or the use of the upper arm is contraindicated, the nurse can assess the blood pressure using the popliteal artery in the leg. The systolic pressure is normally 10 to 40 mm Hg higher at this site, although the diastolic pressure is the same.

Key Concepts

-Vital signs are a person's temperature, pulse, respiration, and blood pressure. Pain and pulse oximetry may also be included as part of the measurement of vital signs. A person's health status is reflected in these indicators of body functions. A change in vital signs might indicate a change in health. -Nurses obtain vital signs as often as a patient's condition requires. Frequency of assessment should be based on institutional policies, medical orders, the patient's medical diagnosis, comorbidities, types of treatments received, and the patient's level of acuity. -Normal body temperature is 35.9ºC to 38ºC (96.7ºF to 100.5ºF), depending on route used for measurement. There are individual variations of these temperatures as well as variations related to physical activity, age, gender, time of day, and state of health. -To accurately assess body temperature, the nurse must know what equipment to use, which site to choose, and what method is appropriate. -The sites most commonly used to assess body temperature are oral (sublingual), tympanic, temporal artery, rectal, and axillary. -The peripheral pulse is a throbbing sensation that can be palpated over a peripheral artery. Characteristics of the peripheral pulse include rate, quality (strong or weak), and rhythm. -An apical pulse is auscultated over the apex of the heart as the heart beats. -The pulse rate is the number of pulsations felt over a peripheral artery or heard over the apex of the heart in 1 minute. The normal pulse rate for adolescents and adults ranges from 60 to 100 beats/min. -Respirations measure the rate of ventilation, breathing in (inhaling) and out (exhaling). Healthy adults breathe about 12 to 20 times each minute. -Blood pressure refers to the force of the moving blood against arterial walls. The pressure rises as the ventricle contracts (systole) and falls as the heart relaxes (diastole). The highest pressure, created during ventricular contraction, is the systolic pressure. When the heart rests between beats during ventricular diastole, the pressure drops. The lowest pressure present on arterial walls at this time is the diastolic pressure. -Blood pressure can be within a wide range and still be normal. A rise or fall of 20 to 30 mm Hg in a person's blood pressure is significant, even if it is within the generally accepted normal range. Optimal blood pressure for adults is defined as less than 120/80 mm Hg.

Sample Documentation

10/18/15 0945 Blood pressure taken in right arm 180/88. Physician notified. Ordered captopril 25 po mg b.i.d. Blood pressure to be repeated 30 minutes after administering medication. —M. Evans, RN

Obtaining Blood Pressure Measurement 16. Assume a position that is no more than 3 feet away from the gauge.

A distance of more than about 3 feet can interfere with accurate readings of the numbers on the gauge.

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.

15. Deflate the cuff and wait 1 minute.

Allowing a brief pause before continuing permits the blood to refill and circulate through the arm.

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.

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.

23. Allow the remaining air to escape quickly. Repeat any suspicious reading, but wait at least 1 minute. 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.

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.

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.

18. Place the bell or diaphragm of the stethoscope firmly but with as little pressure as possible over the brachial artery (Figure 5). 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.

3. Identify the patient.

Identifying the patient ensures the right patient receives the intervention and helps prevent errors.

11. Check that the needle on the aneroid gauge is within the zero mark (Figure 3). If using a mercury manometer, check to see that the manometer is in the vertical position and that the mercury is within the zero level with the gauge at eye level.

If the needle is not in the zero area, the blood pressure reading may not be accurate. Tilting a mercury manometer, inaccurate calibration, or improper height for reading the gauge can lead to errors in determining the pressure measurements.

19. Pump the pressure 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 to 3 mm per second).

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.

6. Select the appropriate arm for application of the cuff.

Measurement of blood pressure may temporarily impede circulation to the extremity.

DELEGATION CONSIDERATIONS

Measurement of brachial artery blood pressure may be delegated to nursing assistive personnel (NAP) or unlicensed assistive personnel (UAP), as well as to licensed practical/vocational nurses (LPN/LVN). The decision to delegate must be based on careful analysis of the patient's needs and circumstances, as well as the qualifications of the person to whom the task is being delegated.

*Estimating Systolic Pressure* 12. Palpate the pulse at the brachial or radial artery by pressing gently with the fingertips (Figure 4).

Palpation allows for measurement of the approximate systolic reading.

9. Palpate the location of the brachial artery. *Center the bladder of the cuff over the brachial artery, about midway on the 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 2). (Taylor 617) Taylor, Carol. Fundamentals of Nursing. Wolters Kluwer Health, 10/2014. VitalBook file. The citation provided is a guideline. Please check each citation for accuracy before use.

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. (Taylor 617) Taylor, Carol. Fundamentals of Nursing. Wolters Kluwer Health, 10/2014. VitalBook file. The citation provided is a guideline. Please check each citation for accuracy before use.

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.

IMPLEMENTATION ACTION 1. Check the medical order or nursing care plan for frequency of blood pressure measurement. More frequent measurement may be appropriate based on nursing judgment.

RATIONALE Provides for patient safety.

DOCUMENTATION Guidelines

Record the findings on paper, flow sheet, or computerized record. Report abnormal findings to the appropriate person. Identify arm used and site of assessment if other than brachial.

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.

26. Remove additional PPE, if used. Perform hand hygiene.

Removing PPE properly reduces the risk for infection transmission and contamination of other items. Hand hygiene deters the spread of microorganisms.

24. When measurement is completed, remove the cuff. Remove gloves, if worn. Cover the patient and help the patient to a position of comfort.

Removing gloves properly reduces the risk for infection transmission and contamination of other items. Ensures patient comfort.

20. Note the point on the gauge at which the first faint, but clear, sound appears that slowly increases in intensity. Note this number as the systolic pressure (Figure 6). Read the pressure to the closest 2 mm Hg.

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.

13. Tighten the screw valve on the air pump.

The bladder within the cuff will not inflate with the valve open.

22. Note the point at which the sound completely disappears. Note this number as the diastolic pressure (Figure 7). Read the pressure to the closest 2 mm Hg.

The point at which the sound disappears corresponds to the beginning of phase V Korotkoff sounds and is generally considered the diastolic pressure reading (Pickering et al., 2004).

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.

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 1). 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 the patient's back. In addition, make sure the patient keeps the legs uncrossed. (Taylor 616) Taylor, Carol. Fundamentals of Nursing. Wolters Kluwer Health, 10/2014. VitalBook file. The citation provided is a guideline. Please check each citation for accuracy before use.

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 (Pickering, et al., 2004). 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 (Pickering et al., 2004). 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. This sitting position ensures accuracy.

4. Close the curtains around the bed and close the door to the room, if possible. Discuss procedure with the patient and assess the patient's ability to assist with the procedure. Validate that the patient has relaxed for several minutes.

This ensures the patient's privacy. Explanation relieves anxiety and facilitates cooperation. Activity immediately before measurement can result in inaccurate results.

EQUIPMENT

•Stethoscope •Sphygmomanometer •Blood pressure cuff of appropriate size •Pencil or pen, paper, flow sheet, or computerized record •Alcohol swab •PPE, as indicated