What are the best sites to measure Blood Pressure (BP) in infants?

From the Guidelines

The best site to measure blood pressure in infants is the right upper arm (brachial artery) using an oscillometric device with a properly sized cuff, as this method is recommended for use in the office setting and is suitable for infants who are unable to cooperate with manual BP determination. When using the upper arm, it is essential to ensure the cuff width covers approximately 40% of the arm circumference between the olecranon and acromion, with the bladder encircling 80-100% of the arm circumference, as stated in 1. Some key points to consider when measuring blood pressure in infants include:

• Proper cuff sizing is crucial, as too small a cuff yields falsely high readings while too large a cuff gives falsely low readings 1.
• The infant should be calm or sleeping during measurement, as crying or agitation can significantly elevate blood pressure readings.
• Oscillometric (automated) devices are commonly used in clinical settings, though auscultatory methods remain the gold standard when precision is critical.
• When measuring BP in premature infants, the lower leg (posterior tibial or dorsalis pedis artery) may also be used when upper extremities are inaccessible due to IV lines or other medical equipment.
• Multiple readings should be taken and averaged for the most accurate assessment of an infant's blood pressure, as recommended in 1. It is also important to note that the oscillometric device used should be validated in neonates and programmed to have an initial inflation value appropriate for infants (generally ≤120 mm Hg), as stated in 1. Overall, measuring blood pressure in the right upper arm using an appropriately sized cuff and an oscillometric device is the recommended method for infants, as it provides accurate and reliable readings, and is suitable for use in the office setting 1.

From the Research

Best Sites to Measure Blood Pressure in Infants

The best sites to measure blood pressure (BP) in infants include the right upper arm and the calf.

• Studies have shown that BP values obtained from the calf are almost identical to those obtained from the arm 2.
• However, another study found a significant difference in diastolic BP measurements between the arm and calf, suggesting that further investigation is needed 3.
• The right upper arm is a commonly used site for BP measurement in infants, and studies have established normative BP values for this site 2, 4.
• The calf is also a suitable site for BP measurement in infants, and reference data are available for BP measurements at this site 5.

Factors to Consider When Measuring BP in Infants

When measuring BP in infants, several factors should be considered, including:

• The size of the BP cuff, which should be selected based on the circumference of the extremity 2, 6.
• The position of the infant, with studies suggesting that the prone position may result in lower BP measurements than the supine position 4.
• The state of the infant, with studies showing that a restful state is essential for accurate BP measurement 4.
• The method of cuff size selection, with visual assessment being an unreliable method 6.

Comparison of Arm and Calf BP Measurements

Studies have compared BP measurements obtained from the arm and calf in infants, with results showing:

• No significant difference in systolic or mean BP measurements between the arm and calf 3.
• A significant difference in diastolic BP measurements between the arm and calf, with the calf measurement being higher 3.
• A moderate correlation between arm and calf BP measurements, suggesting that calf BP measurements may not be equivalent to arm BP measurements 5.