The peripheral pulse is the rhythmic throbbing sensation felt in arteries close to the body’s surface, reflecting the mechanical activity of the heart. This palpable wave is a fundamental measurement used to quickly assess a person’s circulatory status and overall cardiovascular health. It serves as a simple gauge of how effectively the heart is pumping blood throughout the systemic circulation.
The Physical Mechanism
The pulse felt in the extremities is not the direct movement of blood flowing through the vessels, but rather a pressure wave created by the heart’s contraction. This process begins when the left ventricle contracts during systole, forcefully ejecting a volume of blood into the aorta. The sudden surge of volume distends the elastic walls of the large arteries, creating a high-pressure wave.
This pressure wave travels much faster than the blood itself, propagating rapidly along the arterial walls toward the body’s periphery. As the wave moves, it temporarily expands the artery walls, which is the sensation registered by palpation. The elastic recoil of the arteries then helps to sustain the blood flow and pressure until the next heartbeat.
Key Measurement Sites
Palpating the peripheral pulse relies on locating an artery that runs close to the skin’s surface and is supported by a firm structure, typically bone, to allow the pressure wave to be felt. The most common site for a routine assessment is the radial artery, which is found on the thumb-side of the wrist. Here, two or three fingertips are placed gently over the artery, pressing it lightly against the underlying radius bone to feel the distinct beat.
The carotid pulse, located in the neck, is often assessed in emergency situations because it remains palpable even when blood pressure is low. Another frequent location in the upper extremity is the brachial artery, situated on the inside of the elbow (antecubital fossa). This site is routinely used to auscultate blood pressure and is the preferred pulse check location for infants during resuscitation.
In the lower extremities, two common sites are the posterior tibial and dorsalis pedis arteries. The posterior tibial pulse is found just behind the medial malleolus, the prominent bony bump on the inside of the ankle. The dorsalis pedis pulse is found on the top of the foot, slightly lateral to the tendon of the great toe, and assessing these distal sites provides insights into the peripheral perfusion of the limbs.
Interpreting Pulse Characteristics
Once the pulse is located, its assessment moves beyond mere detection to a detailed analysis of its characteristics, providing substantial clinical information. The first characteristic evaluated is the rate, measured in beats per minute (bpm). A normal resting heart rate for an adult generally falls within the range of 60 to 100 bpm.
A pulse rate consistently above 100 bpm is termed tachycardia, which may suggest the heart is working harder to compensate for an underlying issue, like dehydration or fever. Conversely, a rate below 60 bpm is called bradycardia and can be normal in highly conditioned athletes, but may also signal certain heart conduction problems. The rhythm is another important characteristic, referring to the regularity of the beats.
A regular pulse features even intervals between each beat, following a steady tempo. An irregular pulse suggests a disruption in the heart’s electrical signaling, which can be either a predictable pattern (regularly irregular) or a completely chaotic one (irregularly irregular), the latter of which is often associated with a condition like atrial fibrillation. The strength, or amplitude, of the pulse is also assessed and is typically graded on a scale.
A normal pulse is usually graded as strong or 2+, indicating it is easily palpable but not overly forceful. A weak or thready pulse (1+) is difficult to find and suggests a low blood volume or poor cardiac output, often seen in shock or severe illness. Conversely, a bounding pulse (3+) feels forceful and hyperkinetic, which can result from high cardiac output or certain valvular heart diseases that increase the stroke volume.