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18.6E: Pulse

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    7865
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    Pulse is a measurement of heart rate by touching and counting beats at several body locations, typically at the wrist radial artery.

     

    LEARNING OBJECTIVES

     

    Describe the cardiovascular pulse

     

    KEY TAKEAWAYS

    Key Points

     

    • Physiologically, pulse is the expansion of the artery due to pressure from the heartbeat, and thus is most closely correlated to systolic blood pressure.
    • Sometimes the pulse cannot be taken at the wrist and may therefore be taken at the neck against the carotid artery (carotid pulse) or behind the knee ( popliteal artery ).
    • The heart rate may be greater or less than the pulse rate depending upon physiologic demand. In this case, the heart rate is determined by auscultation or audible sounds at the heart apex, not the pulse.
    • Pulse rate is recorded as beats per minute (bpm) and varies with age. A newborn or infant can have a heart rate of approximately 130-150 bpm, while an adult pulse rate is between 50 and 80 bpm.

     

    Key Terms

     

    • popliteal artery: The popliteal artery is defined as the extension of the superficial femoral artery after passing through the adductor canal and adductor hiatus above the knee.
    • radial artery: The main artery that enters the wrist on the side of the thumb, it is the most common location for measuring pulse rate.
    • heart rate: The number of heartbeats per unit of time, usually expressed as beats per minute.
    • pulse rate: The physical expansion of an artery per unit of time, usually expressed as beats per minute.
    • carotid artery: Either of a pair of arteries on each side of the neck that branch from the aorta and supply blood to the head.

    The pulse is the physical expansion of an artery generated by the increase in pressure associated with systole of the heart. Pulse is often used as an equivalent of heart rate due to the relative ease of measurement; heart rate can be measured by listening to the heart directly through the chest, traditionally using a stethoscope.

    image

    Measurement of the pulse: Measurement of the pulse can occur at several locations, including the radial artery shown here.

    Pulse rate or velocity is usually measured either at the wrist from the radial artery and is recorded as beats per minute (bpm). Other common measurement locations include the carotid artery in the neck and popliteal artery behind the knee

    Pulse varies with age; a newborn or infant can have a heart rate of about 130-150 bpm. A toddler’s heart will beat about 100-120 times per minute, an older child’s heartbeat is around 60-100 bpm, adolescents around 80-100 bpm, and a healthy adults pulse rate is anywhere between 50 and 80 bpm.

    The heart rate may be greater or less than the pulse rate depending upon physiologic demand. In this case, the heart rate is determined by auscultation or audible sounds at the heart apex, not the pulse. The pulse deficit (difference between heartbeats and pulsations at the periphery) is determined by simultaneous palpation at the radial artery and auscultation at the heart apex.

     

    Measurement Techniques

     

    While a simple measurement of pulse rate is achievable by anyone, trained medical staff are capable of much more accurate measurements. Radial pulse is commonly measured using three fingers: the finger closest to the heart used to occlude the pulse pressure, the middle finger used get a crude estimate of blood pressure, and the finger most distal to the heart used to nullify the effect of the ulnar pulse as the two arteries are connected via the palmar arches.

    Where more accurate or long-term measurements are required, pulse rate, pulse deficits, and more physiologic data are readily visualized by the use of one or more arterial catheters connected to a transducer and oscilloscope. This invasive technique has been commonly used in intensive care since the 1970’s. The rate of the pulse is observed and measured by tactile or visual means on the outside of an artery and is recorded as beats per minute. The pulse may be further indirectly observed under light absorbencies of varying wavelengths with assigned and inexpensively reproduced mathematical ratios. Applied capture of variances of light signal from the blood component hemoglobin under oxygenated vs. deoxygenated conditions allows the technology of pulse oximetry.