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May.27.2020

Blood Pressure: Auscultation of Upper Extremity (Ambulatory) - CE

ALERT

If unable to palpate an artery because of a weak pulse, use an ultrasonic stethoscope (Figure 1)Figure 1.

Blood pressure (BP) measurements with an electronic BP device may be affected by excessive movement, such as that with seizures, tremors, or shivering, and irregular heart rates.

OVERVIEW

BP is the force exerted by blood against the vessel walls. During a normal cardiac cycle, BP reaches a peak followed by a trough. The peak pressure occurs when the heart’s ventricular contraction, or systole, forces blood under high pressure into the aorta. When the ventricles relax, the blood remaining in the arteries exerts a trough, or diastolic, pressure against the arterial wall. Diastolic pressure is the consistent, minimal pressure exerted against the arterial wall.

Patients at risk for alterations in BP measurement include those who have:

  • Circulatory shock (hypovolemic, septic, cardiogenic, or neurogenic)
  • Acute or chronic pain
  • Rapid IV infusion of fluids or blood products
  • Increased intracranial pressure
  • Postoperative status
  • Preeclampsia of pregnancy

The standard unit for measuring BP is millimeters of mercury (mm Hg). The measurement indicates the height to which the BP can sustain the column of mercury.

The most common methods for measuring BP are auscultation using a sphygmomanometer and a stethoscope and measurement using an electronic BP monitor. Palpation may be used to obtain an estimate of systolic BP before using the auscultation method.

During auscultation, as the sphygmomanometer cuff is deflated, five different sounds, called Korotkoff sounds, are heard over the artery. Each sound has a distinct characteristic (Figure 2)Figure 2. BP is recorded with the systolic reading (first Korotkoff sound) before the diastolic reading (beginning of the fifth Korotkoff sound). The difference between systolic pressure and diastolic pressure is the pulse pressure. For a BP of 120/80 mm Hg, the pulse pressure is 40 mm Hg, the difference between 120 mm Hg and 80 mm Hg.undefined#ref3">3

Cuff size should be proportionate to the extremity circumference (Table 1)Table 1. Most adults require a large adult cuff. An improper-size cuff produces inaccurate BP measurements (Table 2)Table 2. Studies show that using a cuff that is too narrow results in an overestimation of BP and using a cuff that is too wide results in an underestimation of BP.1

When measuring BP in the upper arm is not possible—for example, when the available BP cuffs do not fit the upper arm properly—BP may be measured in the forearm. To obtain the most accurate reading, the health care team member must use the proper size BP cuff for the forearm, which typically has a smaller circumference than the upper arm. BP measurements in the forearm and upper arm are not interchangeable. Forearm measurements tend to be higher than upper-arm measurements with the greater variability in systolic BPs.6 The thigh or calf can be used if measurement of the upper arms and forearms is not possible.1

EDUCATION

  • Provide developmentally and culturally appropriate education based on the desire for knowledge, readiness to learn, and overall neurologic and psychosocial state.
  • Explain the equipment and the procedure to the patient and family.
  • Instruct the patient about ambulatory BP threshold guidelines. In adults, normal BP is less than 120/80 mm Hg3 (Table 3)Table 3.
  • Educate the patient and family about the risk factors for hypertension.
    • Family history of hypertension, premature heart disease, lipidemia, or renal disease
    • Obesity
    • Cigarette smoking
    • Heavy alcohol consumption
    • High blood cholesterol and triglyceride levels
    • Prolonged stress from psychosocial and environmental factors
    • Sedentary lifestyle
  • Educate the patient and family regarding the primary strategies for preventing hypertension.4
    • Managing weight
    • Limiting sodium and saturated fat in the diet
    • Taking medications as prescribed
    • Maintaining adequate intake of dietary potassium and calcium
    • Engaging in daily exercise
    • Limiting alcohol intake
    • Avoiding tobacco products
  • Teach the patient the signs and symptoms of high BP (e.g., shortness of breath, severe headache, severe anxiety, pulsations in neck or head) and instruct him or her on when to seek additional care.
  • Instruct the patient to ensure that he or she has adequate rest before BP measurements and that they are performed at the same time each day using the same arm with the patient in the same position, either sitting or lying down.
  • Explain to the patient that he or she must remain still and quiet during the procedure.
  • Encourage questions and answer them as they arise.

PROCEDURE

  1. Perform hand hygiene.
  2. Introduce yourself to the patient.
  3. Verify the correct patient using two identifiers.
  4. Explain the procedure to the patient and ensure that he or she agrees to treatment.
  5. Ensure that evaluation findings are communicated to the clinical team leader per the organization’s practice.
  6. Review the patient’s record for a history of hypertension, cardiovascular disease, renal disease, diabetes, and other factors that influence BP (e.g., weight, smoking, medications).
  7. Evaluate the patient for signs and symptoms of BP alterations.
    1. Determine if the patient is at risk for high BP if he or she is experiencing these signs and symptoms:
      1. Headache (usually occipital)
      2. Facial flushing
      3. Nosebleed
      4. Fatigue
    2. Determine if the patient is at risk for low BP if he or she is experiencing these signs and symptoms:
      1. Dizziness
      2. Mental confusion
      3. Restlessness
      4. Pale, dusky, or cyanotic skin and mucous membranes
      5. Cool, mottled skin over the extremities
  8. Determine the best site for BP measurement. Avoid applying the cuff to the patient’s arm in these situations:
    1. IV fluids are infusing.
    2. An arteriovenous shunt or fistula is present.
    3. Ipsilateral breast or axillary surgery has been performed.
    4. The arm has been traumatized.
    5. The arm has known infections or medical conditions (e.g., those causing vasoconstriction or a tumor pressing on the vascular supply).
    6. The arm has a cast or bulky bandage.
  9. If available, review the previous baseline BP and measurement site from the patient’s record.
  10. Determine the appropriateness of using an electronic BP measurement (Box 1)Box 1.
  11. Ensure that the patient has not exercised, ingested caffeine, or smoked for 30 minutes2 before BP measurement. Ensure that the patient does not have to void.
  12. Rationale: The urge to void can significantly increase BP. 5
  13. Ensure that the room is warm.
  14. Rationale: Exposure to cold can significantly increase systolic BP. 5
  15. Measure the patient’s arm circumference and select the appropriate-size cuff (Figure 3)Figure 3 (Table 1)Table 1.
  16. Rationale: An improper-size cuff produces inaccurate BP measurements. Studies show that using a cuff that is too narrow results in an overestimation of BP and using a cuff that is too wide results in an underestimate of BP. 1
  17. Inform the patient that BP is going to be taken and that the cuff will squeeze the arm.

Auscultation Method

  1. Perform hand hygiene.
  2. Verify the correct patient using two identifiers.
  3. Explain the procedure to the patient and ensure that he or she agrees to treatment.
  4. Ensure that evaluation findings are communicated to the clinical team leader per the organization’s practice.
  5. Have the patient sit or lie down. Record the patient’s position when performing orthostatic vital signs. If the patient is sitting, ensure that his or her back is supported.5
  6. Rationale: BP is generally higher in the supine position than the sitting position. 5
  7. Position the patient’s forearm at heart level, supported, with the palm facing up (Figure 4)Figure 4. If the patient is sitting, instruct him or her to keep the feet flat on the floor with the legs uncrossed. If the patient is supine, ensure that his or her legs are not crossed.
  8. Rationale: If the patient’s arm is not supported at heart level, a lower BP will be recorded when the arm is above heart level, and a higher BP will be recorded when the arm is below heart level. 1 Leg crossing can falsely increase systolic and diastolic BP.
  9. Expose the patient’s arm fully by removing constricting clothing. Do not place the BP cuff over clothing.
  10. Rationale: Placing the cuff over clothing may affect the BP measurement.
  11. Apply the BP cuff.
    1. Upper arm
      1. Palpate the brachial artery for a pulse (Figure 5A)Figure 5A.
      2. Position the cuff in the antecubital space (Figure 5B)Figure 5B.
      3. Apply the cuff above the artery by centering the arrows marked on the cuff over the artery so that the end of the cuff is 2 to 3 cm (about 1 in) above the antecubital fossa to allow room for placement of the stethoscope (Figure 5C)Figure 5C.1 If the cuff has no center arrows, estimate the center of the bladder and place it over the artery.
      4. Rationale: Positioning the cuff bladder directly over the brachial artery ensures that proper pressure is applied during inflation.
      5. Wrap the fully deflated cuff evenly and snugly around the patient’s upper arm.
      6. Rationale: A loose-fitting cuff causes false-high readings.
    2. Forearm
      1. Palpate the radial artery for a pulse.
      2. Position the cuff above the styloid process.
      3. Apply the cuff above the artery by centering the arrows marked on the cuff over the radial artery with the lower edge of the cuff positioned about 2.5 cm (1 in) above the styloid process.6 If the cuff has no center arrows, estimate the center of the bladder and place it over the artery.
      4. Rationale: Positioning the cuff bladder directly over the radial artery ensures that proper pressure is applied during inflation.
      5. Wrap the fully deflated cuff evenly and snugly around the patient’s forearm.
      6. Rationale: A loose-fitting cuff causes false-high readings.
  12. Position the manometer vertically at eye level.
  13. Rationale: Looking up or down at the scale can result in incorrect readings.
  14. Ask the patient not to speak while BP is being measured.
  15. Optional step: Estimate the patient’s systolic BP by palpation.
    1. Locate the brachial or radial pulse.
    2. Palpate the artery distal to the cuff with the fingertips of the nondominant hand while inflating the cuff rapidly to a pressure above the point at which the pulse disappears.
    3. Slowly deflate the cuff and observe the point when the pulse reappears.
    4. Deflate the cuff fully.
  16. Place the stethoscope earpieces in the ears and ensure that the sounds are clear, not muffled.
  17. Locate the brachial or radial artery, as appropriate, and place the diaphragm of the stethoscope over it below the lower edge of the cuff.
  18. Rationale: Using the bell of the stethoscope may cause inaccurate reading. 5
    1. Do not let the diaphragm touch the cuff or clothing.
    2. Do not place the diaphragm under the cuff.5
    3. Do not place excessive pressure on the stethoscope head.5
    4. If unable to palpate the artery because of a weakened pulse, use an ultrasonic stethoscope (Figure 1)Figure 1.
    5. Rationale: Proper stethoscope placement ensures the best sound reception. An improperly positioned stethoscope causes muffled sounds that can result in false-low systolic and false-high diastolic readings. Use of the bell and excessive pressure on the diaphragm of the stethoscope can lead to inaccurate BP measurements. 5
  19. Turn the valve of the pressure bulb clockwise until it is tight. Quickly inflate the cuff above the patient’s estimated palpated systolic pressure, the patient’s previously documented systolic pressure, or the point at which Korotkoff sounds cease.
  20. Rationale: Closing the valve prevents air leak during inflation. Rapid cuff inflation ensures accurate measurement of systolic pressure.
  21. Slowly release the pressure bulb valve, allowing the manometer needle to fall slowly and continuously at a rate of 2 to 3 mm Hg per second.5
  22. Rationale: Too rapid or too slow a decline in the mercury level causes inaccurate readings.
  23. Observe the point on the manometer at which the first Korotkoff sound is heard, indicating the systolic BP. The sound will slowly increase in intensity.
  24. Rationale: This first Korotkoff sound is a snapping sound. This sound for at least two consecutive heartbeats reflects the systolic BP.
  25. Continue to deflate the cuff gradually; observe the point on the manometer at which all Korotkoff sounds disappear, indicating the diastolic BP.
  26. Rationale: The fifth Korotkoff sound falls silent as the cuff pressure drops below the diastolic pressure. Thus, the beginning of the fifth Korotkoff sound indicates diastolic pressure in adults. 5 The fourth Korotkoff sound involves distinct muffling of sounds and indicates diastolic pressure in children. 7
  27. When the sounds disappear, quickly deflate the cuff completely.
  28. Remove the cuff from the patient’s arm unless a repeat measurement is needed.
  29. Rationale: Continuous cuff inflation causes arterial occlusion, resulting in numbness and tingling of the arm.
  30. If this is the patient’s first BP evaluation, repeat the procedure on the other arm. If there is a consistent difference between the BP in the patient’s arms, use the arm with the higher pressure.1
  31. Rationale: Comparison of BP in both arms helps detect cardiovascular, neurologic, and musculoskeletal abnormalities. A normal difference of up to 10 mm Hg may exist between arms. 1
  32. Assist the patient with resuming a comfortable position and return any removed clothing. Inform the patient of the BP reading, as appropriate.
  33. Clean the BP cuff per the manufacturer’s instructions and the organization’s practice. Clean the earpieces and diaphragm of the stethoscope per the organization’s practice.
  34. Return the equipment to its assigned storage space.
  35. Perform hand hygiene.
  36. Document the procedure in the patient’s record.

Electronic Method

  1. Perform hand hygiene.
  2. Verify the correct patient using two identifiers.
  3. Explain the procedure to the patient and ensure that he or she agrees to treatment.
  4. Ensure that evaluation findings are communicated to the clinical team leader per the organization’s practice.
  5. Have the patient sit or lie down. Record the patient’s position when performing orthostatic vital signs. If the patient is sitting, ensure that his or her back is supported.5
  6. Rationale: BP is generally higher in the supine position than the sitting position. 5
  7. Plug in the device and place it near the patient’s arm, then choose an appropriate-size cuff (Table 1)Table 1. Ensure that the BP cuff is appropriate for the electronic device per the manufacturer’s instructions.
  8. Prepare the BP cuff by manually squeezing all the air out of it and connecting it to the connector hose.
  9. Position the patient’s forearm, supported, at heart level with the palm facing up (Figure 4)Figure 4. If the patient is sitting, instruct him or her to keep the feet flat on the floor with the legs uncrossed. If the patient is supine, ensure that his or her legs are not crossed.
  10. Rationale: If the patient’s arm is not supported at heart level, a lower BP will be recorded when the arm is above heart level, and a higher BP will be recorded when the arm is below heart level. 1 Leg crossing can falsely increase systolic and diastolic BP.
  11. Expose the upper arm fully by removing constricting clothing. Do not place the BP cuff over clothing.
  12. Rationale: Placing the cuff over clothing may affect the BP measurement.
  13. Apply the BP cuff. Do not place the cuff over a bony prominence, superficial nerve, or joint.1
    1. Upper arm
      1. Palpate the brachial artery for a pulse (Figure 5A)Figure 5A.
      2. Position the cuff in the antecubital space (Figure 5B)Figure 5B.
      3. Apply the cuff above the artery by centering the arrows marked on the cuff over the artery so that the end of the cuff is 2 to 3 cm (about 1 in) above the antecubital fossa (Figure 5C)Figure 5C.1 If the cuff has no center arrows, estimate the center of the bladder and place it over the artery.
      4. Rationale: Positioning the cuff bladder directly over the brachial artery ensures that proper pressure is applied during inflation.
      5. Wrap the fully deflated cuff evenly and snugly around the patient’s upper arm.
      6. Rationale: A loose-fitting cuff causes false-high readings.
    2. Forearm
      1. Palpate the radial artery for a pulse.
      2. Position the cuff above the styloid process.
      3. Apply the cuff above the artery by centering the arrows marked on the cuff over the radial artery with the lower edge of the cuff positioned about 2.5 cm (1 in) above the styloid process.6 If the cuff has no center arrows, estimate the center of the bladder and place it over the artery.
      4. Rationale: Positioning the cuff bladder directly over the radial artery ensures that proper pressure is applied during inflation.
      5. Wrap the fully deflated cuff evenly and snugly around the patient’s forearm.
      6. Rationale: A loose-fitting cuff causes false-high readings ( Table 2)Table 2.
  14. Ask the patient not to speak while BP is being measured.
  15. Verify that the connector hose between the cuff and the machine is not kinked.
  16. Set the frequency control for automatic or manual and then press the start button following the manufacturer’s instructions.
  17. When the deflation is complete, observe the digital display, which provides the most recent values. Displays vary among different types of BP monitors.
  18. Obtain additional readings by pressing the start button rather than the cancel button.
  19. Rationale: Pressing the cancel button immediately deflates the cuff.
  20. If frequent BP measurements are required, leave the cuff in place. Set the frequency of BP measurements and the upper and lower alarm limits for systolic, diastolic, and mean BP readings. If repeat measurements are not needed, remove the cuff from the patient’s arm.
  21. Rationale: Leaving the cuff in place when serial measurements are not needed may cause arterial occlusion, resulting in numbness and tingling of the arm.
    1. Remove the cuff at regular intervals to inspect the underlying skin integrity.
    2. Alternate BP sites, if possible.
    3. Patients with abnormal bleeding tendencies are at risk for microvascular rupture from repeated inflations.
  22. If this is the patient’s first BP evaluation, repeat the procedure on the other arm. If there is a consistent difference between the BP in the patient’s arms, use the arm with the higher pressure.1
  23. Rationale: Comparison of BP in both arms helps detect cardiovascular, neurologic, and musculoskeletal abnormalities. A normal difference of up to 10 mm Hg may exist between arms. 1
  24. Assist the patient with resuming a comfortable position and return any removed clothing. Inform the patient of the BP reading, as appropriate.
  25. Clean the BP cuff and electronic device per the manufacturer’s instructions and the organization’s practice.
  26. Return the equipment to its assigned storage space.
  27. Perform hand hygiene.
  28. Document the procedure in the patient’s record.

EXPECTED OUTCOMES

  • BP is within acceptable range for patient’s age and body size.
  • Patient tolerates procedure.
  • No significant difference exists between left-arm and right-arm BP readings

UNEXPECTED OUTCOMES

  • BP is above acceptable range for the patient’s age and body size.
  • BP is below acceptable range or insufficient for adequate perfusion and oxygenation of tissues for the patient’s age and body size.
  • BP reading cannot be obtained.
  • Patient experiences orthostatic hypotension.
  • A significant difference exists between left-arm and right-arm BP readings.

DOCUMENTATION

  • BP measurement
  • Method
  • Site used and patient’s position
  • BP measurement after administration of specific therapies
  • Signs and symptoms of BP alterations
  • Evaluation findings communicated to the clinical team leader per the organization’s practice
  • Abnormal findings
  • Unexpected outcomes and related interventions
  • Education

PEDIATRIC CONSIDERATIONS

  • The right arm is preferred for BP measurement in children for consistency and comparison with standardized BP measurement tables for age and weight.7
  • BP measurement may frighten children. A child should be prepared for the squeezing feeling of an inflated BP cuff by comparing the sensation to an elastic band on a finger or a tight hug on the arm.
  • The child’s BP should be measured before performing anxiety-producing tests or procedures.
  • A child’s or adolescent’s awareness of body size and age should be considered during the BP measurement.
    • Heavier and taller children have higher BPs than smaller children of the same age.
    • During adolescence, BP continues to vary according to body size.
  • Korotkoff sounds are difficult to hear in children because of the low frequency and amplitude. Using a pediatric stethoscope is helpful.
  • Although the beginning of the fifth Korotkoff sound indicates diastolic pressure in adults, the fourth Korotkoff (distinct muffling) indicates diastolic pressure in children.
  • An acceptable chart for expected ranges that is based on age, height, and weight should be used.

OLDER ADULT CONSIDERATIONS

  • Older adults, especially frail older adults, typically have lost upper-arm mass, requiring special attention to BP cuff size.
  • Older adults’ skin is more fragile and susceptible to damage from cuff pressure when BP measurements are frequent. More frequent evaluations of the skin under the cuff or rotation of BP sites is recommended.
  • Older adults have increased systolic pressure related to decreased vessel elasticity.
  • In most cases, older adults experience a fall in BP after eating.
  • Older adults should be instructed to change position slowly and to wait after each change to avoid postural hypotension and prevent injuries.

REFERENCES

  1. American Association of Critical-Care Nurses (AACN). (2016). AACN practice alert: Obtaining accurate noninvasive blood pressure measurements in adults. Critical Care Nurse, 36(3), e12-e16. doi:10.4037/ccn2016590 (Level VII)
  2. American Heart Association (AHA). (2017). Monitoring your blood pressure at home. Retrieved April 14, 2020, from https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings/monitoring-your-blood-pressure-at-home#.Wuct7ExFwy9 (Level VII)
  3. American Heart Association (AHA). (2017). Understanding blood pressure readings. Retrieved April 14, 2020, from https://www.heart.org/en/health-topics/high-blood-pressure/understanding-blood-pressure-readings#.Wucr9UxFwy9 (Level VII)
  4. American Heart Association (AHA). (2017). The facts about high blood pressure Retrieved April 14, 2020, from https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure (Level VII)
  5. Kallioinen, N. and others. (2017). Sources of inaccuracy in the measurement of adult patient’s resting blood pressure in clinical settings: A systematic review. Journal of Hypertension, 35(3), 421-441. doi:10.1097/HJH.0000000000001197 (Level I)
  6. Schimanski, K. and others. (2014). Comparison study of upper arm and forearm non-invasive blood pressures in adult emergency department patients. International Journal of Nursing Studies, 51(12), 1575-1584. doi:10.1016/j.ijnurstu.2014.03.008 (Level IV)
  7. Schroeder, M.L. and others. (2019). Chapter 27: The child with cardiovascular dysfunction. In M.J. Hockenberry, D. Wilson, C.C. Rodgers (Eds.), Wong’s nursing care of infants and children (11th ed., pp. 958-1091). St. Louis: Elsevier.

Elsevier Skills Levels of Evidence

  • Level I - Systematic review of all relevant randomized controlled trials
  • Level II - At least one well-designed randomized controlled trial
  • Level III - Well-designed controlled trials without randomization
  • Level IV - Well-designed case-controlled or cohort studies
  • Level V - Descriptive or qualitative studies
  • Level VI - Single descriptive or qualitative study
  • Level VII - Authority opinion or expert committee reports