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To obtain an accurate blood pressure (BP) measurement, use the proper cuff size for the patient.
BP measurement is taken for a variety of diagnostic and therapeutic decisions; therefore, measurements must be correct and reproducible. Values that fall outside the expected range warrant further physical examination, investigation, and practitioner notification. BP evaluation should be part of a complete physical assessment of the patient.
Intraarterial measurement with an invasive catheter is the gold standard for obtaining an arterial BP. Because the intraarterial method is not practical for most pediatric patients, noninvasive blood pressure (NIBP) measurements are used. The standard of care is to obtain NIBP measurements via auscultation using a sphygmomanometer. This standard requires the health care team member to take the BP measurement in the right upper arm with the stethoscope placed over the brachial artery.undefined#ref2">2 This proven and consistent method for measuring BP yields reliable and reproducible results.2 Although the standard of care is to obtain an NIBP measurement in the upper right arm, obtaining a secondary BP measurement from the calf in a pediatric patient is an alternative if a BP reading cannot be obtained in the upper arm.
When using sphygmomanometry, the health care team member determines the pressure necessary to collapse the artery in the arm by inflating the cuff. As the cuff is deflated, the team member notes the pressure as sounds produced by the arterial pulse waves (Korotkoff sounds).
NIBP can also be measured using oscillometry or palpation. BP values obtained from oscillometric (automated) devices differ from values obtained by auscultation. Oscillometric devices are useful when auscultation is difficult or frequent BP measurements are necessary. Oscillometric devices measure BP by detecting oscillations on the walls of the occluded artery as the cuff is deflated, calculating systolic blood pressure (SBP) and diastolic blood pressure (DBP) values from measurements of the mean arterial BP. Elevated BP readings obtained using an oscillometric device should be remeasured with a sphygmomanometer if possible.
Whichever NIBP method is chosen, the cuff size (inner inflatable bladder) of the measuring device is an important factor in the accuracy of the BP measurement. For a child, the bladder cuff width should be approximately 40% of the circumference6 of the arm (Figure 1), measuring at a point midway between the olecranon (elbow) and acromion (bony projection of the shoulder blade)3,7 (Figure 2), and the bladder cuff length should cover 80% to 100% of the arm circumference.6 The American Heart Association’s recommendations (Table 1)6 help the health care team member select an appropriate size cuff for the child, which directly reflects the radial arterial pressure when used on the upper arm.3 Extremity circumference should be used when measuring for cuff size as well as when determining placement. For a neonate or infant, the cuff bladder width should be approximately 50% of the mid-arm circumference.1
Standard BP tables used to determine hypertension status are based on auscultatory measurements. However, BP values obtained with oscillometric methods can be reliable and consistent if recorded in standardized conditions with a well-functioning measurement device.
Normal BP is defined as SBP and DBP less than the 90th percentile for age, height, and gender.5 Prehypertensive BP is defined as average SBP or DBP greater than or equal to the 90th percentile but less than the 95th percentile.5 Hypertension is defined as average SBP or DBP greater than or equal to the 95th percentile for age, height, and gender measured on at least three separate occasions.5
Current charts for BP values in children are based on gender, age, and height. Current national BP standards for children are based on BP values obtained with a mercury sphygmomanometer and do not apply to values obtained with oscillometric devices, which tend to overestimate BP and hypertension (Table 2).5
Rationale: Avoiding extremities that have wounds, IV lines, vascular compromise, fragile bones, or injuries helps prevent injury to the extremity. Pressure created by the inflated bladder of the BP device can temporarily impair blood flow and compromise circulation in an extremity that already has impaired circulation.
Do not use a cuff that is smaller than appropriate; doing so can lead to false high BP readings. Do not use a cuff that is wider or larger than appropriate; doing so may produce false low readings.
Rationale: Sitting upright is the optimal position for BP measurement. The sitting position ensures that the midpoint of the arm is at the level of the heart (right atrium). The BP may be falsely elevated if the patient actively holds his or her arm at the level of the heart.
Keep a patient who is critically ill in a position that maintains hemodynamic stability. When taking a BP measurement in a patient who is supine, support the arm on a pillow to ensure that it is at the level of the heart.
Rationale: Proper cuff application improves the accuracy of the measurement.
Remove clothing with sleeves; rolling up a sleeve may cause a tourniquet effect around the upper arm.
Rationale: Korotkoff sounds are heard more easily with the bell of the stethoscope in younger children.
Rationale: Proper positioning of the earpieces allows the best sound transmission.
Ensure that the room is quiet so Korotkoff sounds are audible.
Avoid placing excessive pressure on the brachial artery because doing so may affect Korotkoff sounds.
Overinflating the cuff may cause discomfort to the patient.
Avoid deflating the cuff too rapidly; doing so may cause inaccurate BP measurements.
Rationale: K1 indicates SBP.
Rationale: Korotkoff sounds can often be heard through the entire period of cuff deflation; absence of sounds (K5) denotes DBP.
Rationale: Continuing to deflate the cuff slowly ensures that no further sounds are audible.
Rationale: BP values vary widely because of physiologic variables, and further evaluation may be necessary.
Rationale: Adjusting the settings helps ensure accurate readings and prevents unnecessarily high inflation of the cuff, which causes excessive discomfort for the patient.
If the BP measurement is elevated, measure BP using the auscultatory method.
Reportable conditions: Inability to obtain BP values because of agitation or other factors, BP values that remain higher or lower than expected or vary significantly from the patient’s baseline values, significant differences between BP values in the upper and lower extremities
*In these skills, a “classic” reference is a widely cited, standard work of established excellence that significantly affects current practice and may also represent the foundational research for practice.
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