Exam 1 Review:  Chapter 19:  Pulse

pulse - The rhythmical throbbing of arteries produced by the regular contractions of the heart, generally reported in beats per minute especially as palpated at the wrist or in the neck; in an artery this vital sign is due to the expansion and contraction of the elastic walls of the artery by the action of the ventricles contracting upon the column of blood in the arterial system; on the commencement of the diastole of the ventricle, the semilunar valves are closed, and the aorta recoils by its elasticity so as to force part of its contents into the vessels farther onwards; these, in turn, as they already contain a certain quantity of blood, expand, recover by an elastic recoil, and transmit the movement with diminished intensity; thus a series of movements, gradually diminishing in intensity, pass along the arterial system; for the sake of convenience, the radial artery at the wrist is generally chosen to detect the precise character of this vital sign; observing this vital sign gives information about both the rate and the rhythm of the heart; its rate varies with age, position, sex, stature, physical and psychical influences, etc.


Taking a pulse

Try taking your pulse at the following sites (see figure).

  • Radial Pulse:  This is probably what we're most familiar with when visiting the doctor's office. Take two fingers, preferably the 2nd and 3rd finger, and place them in the groove in the wrist that lies beneath the thumb. Move your fingers back and forth gently until you can feel a slight pusation - this is the pulse of the radial artery which delivers blood to the hand. Don't press too hard, or else you'll just feel the blood flowing through your fingers!
  • Carotid Pulse:  The carotid arteries supply blood to the head and neck. You can feel the pulse of the common carotid artery by taking the same two finger and running them alongside the outer edge of your trachea (windpipe). This pulse may be easier to find than that of the radial artery. Since the carotid arteries supply much of the blood to the brain, it's important not to press on both of them at the same time!
  • Femoral pulse:  The femoral atery carries blood to parts of the leg. Aside from the carotid artery, it is another common site to check for a pulse in an emergency situation. Think of an imaginary line running from your hip to the groin. The approximate superficial location of the femoral artery lies 2/3 of the way in from the hip.

    The other following sites can also be tried:

    1. Facial artery: Gently run a finger along the lower edge of the jaw bone. Just beyond the 'chin' on either side, you might be able to feel the pulse of the facial artery.
    2. Brachial artery: Flex your bicpes muscle. Press your thumb or a few fingers into the groove created between the biceps and other muscles, approximately 5cm from the armpit. You should be able to feel the pulse of the brachial artery. This is the major artery supplying blood to the forearm.
    3. Abdominal aorta: Individuals may be able to note a slight pulsation near the stomach when lying down in a relaxed position. This pulsation is caused by the abdominal aorta. At the level of the umbilicus (belly button), the aorta splits into the left and right common iliac ateries which deliver blood to the legs.
    4. Popliteal atery: This artery lies behind the knee. Bend your knee slightly and feel in the soft area behind the knee.

    Explanation:
    The pulse represents the beating of the heart, specifically the ejection of blood from the left ventricle to the systemic circulation of the body. The ventricles (right and left) have two phases: diastole or the time when the ventricles relax so they can fill with blood, and systole, the time when the ventricles contract to send blood either to the lungs (from the right side of the heart), or to the rest of the body (from the left side of the heart). Blood from the left side of the heart first enters the aorta, the largest artery in the body. The aorta branches into smaller arteries which carry blood to all part of the body.

    The pulse represents the variation in blood pressure from diastole to systole. During diastole, blood pressure falls, but increases after systole as the heart pumps more blood into the arterial tree. You feel this difference when taking your pulse. Clinicians use a device called a sphygmomanometer (blood pressure cuff) to measure the systolic and diastolic blood pressures. The average adult has a systolic blood pressure ~120-150 mm Hg (mercury), an average diastolic blood pressure ~80 mm Hg, and an average pulse of 72 beats/minute.

    Useful References:
    The human heart, an exploration


  • Korotkoff sounds - Technically, there are five sounds which are heard as the blood pressure in the syphgmomanometer cuff is released during the measurement of arterial pressure; these are described as:

    In ordinary clinical practice, the first Korotkoff sound is the "sharp thud" associated with the first squirt of blood passing through the artery when cuff pressure has dropped slightly below systolic pressure in the artery, and we note the blood pressure at the time of the "first" Korotkoff sound as the systolic blood pressure reading; the "last" Korotkoff sound is the soft blowing sound associated with the final squirt of blood passing through the artery when cuff pressure is just slightly above diastolic pressure and the artery will still close before the next beat of the heart (pulse pressure wave), and we note the blood pressure at the time of the "last" Korotkoff sound as the diastolic blood pressure reading.

    pulse pressure - The two numbers (measured in mm of Hg = Torr) which represent the range of blood pressure in an artery between (1) ventricular contraction, which produces the systolic pulse measurement, and (2) ventricular relaxation, the diastolic pressure measurement which is maintained by the elasticity and muscular tone of the arterial tree between heart beats; a pulse pressure of approximately 40 (120 - 80) is considered normal; arterial pulse pressure can be affected by stroke volume, arterial compliance, and heart rate; changes noted in the pulse pressure have clinical diagnostic significance.

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