Pulse: Encyclopedia - Pulse

Pulse

In medicine, a person's pulse is the throbbing of their arteries as an effect of the heart beat. It can be felt at the neck, at the wrist and other places.

The pulse results from pressure waves moving through the blood vessels, which are pliable; it is not caused by the forward movement of the blood. When the heart contracts, blood is ejected into the aorta and the aorta stretches. At this point the wave of distention (pulse wave) is most pronounced, but relatively slow-moving (3 to 5 m/s). As it travels towards the peripheral blood vessels, it gradually diminishes and becomes faster. In the large arterial branches, its velocity is 7 to 10 m/s; in the small arteries, it is 15 to 35 m/s. The pressure pulse is 15 or more times more rapidly transmitted than the blood flow.

The term pulse is also used, although incorrectly, to denote the frequency of the heart beat, usually measured in beats per minute. In most people, the pulse is an accurate measure of heart rate. Under certain circumstances, including arrhythmias, some of the heart beats are ineffective and the aorta is not stretched enough to create a palpable pressure wave. The pulse is irregular and the heart rate can be (much) higher than the pulse rate. In this case, the heart rate should be determined by auscultation of the heart apex, in which case it is not the pulse. The pulse deficit (difference between heart beats and pulsations at the periphery) should be determined by simultaneous palpation at the radial artery and auscultation at the heart apex.

A normal pulse rate for a healthy adult, while resting, can range from sixty to ninety beats per minute (BPM). During sleep, this can drop to as low as forty BPM; during strenuous exercise, it can rise as high as 200–220 BPM. Generally, pulse rates are higher in younger persons. A resting heart rate for an infant is as high as or higher than an adult's pulse rate during strenuous exercise.

Besides its rate, the pulse has other qualities which reflect the state of the cardiovascular system, such as its rhythm, fullness and the shape of the pulse wave. Certain diseases cause characteristic changes in these qualities. The absence of a pulse at the temple of the skull can be a sign of giant cell arteritis; absent or decreased pulses in the limbs may indicate peripheral artery occlusive disease.

Pulses are manually palpated with fingers or thumb. When palpating the carotid artery, the femoral artery or the brachial artery, the thumb may be used. However, the thumb has its own pulse which can interfere with detecting the patient's pulse at other points, where two or three fingers should be used. Fingers or thumb must be placed near an artery and pressed gently against a firm structure, usually a bone, in order to feel the pulse.

Pulse - Common pulse points

• radial pulse - located on the thumb side of the wrist (radial artery)
• ulnar pulse - located on the little finger side of the wrist (ulnar artery)
• carotid pulse - located in the neck (carotid artery). The carotid artery should be palpated gently. Stimulating its baroreceptors with vigorous palpitation can provoke severe bradycardia or even stop the heart in some sensitive persons. Also, a person's two carotid arteries should not be palpated at the same time, to avoid a risk of fainting or brain ischemia.
• brachial pulse - located between the biceps and triceps, on the medial side of the elbow cavity; frequently used in place of carotid pulse in infants (brachial artery)
• femoral pulse - located in the thigh (femoral artery)
• popliteal pulse - located behind the knee in the popliteal fossa, found by holding the bent knee. The patient bends the knee at approximately 120°, and the physician holds it in both hands to find the popliteal artery in the pit behind the knee.
• dorsalis pedis pulse - located on top of the foot (dorsalis pedis artery)
• tibialis posterior pulse - located in the back of the ankle behind the medial malleolus (posterior tibial artery).
• temporal pulse - located on the temple directly in front of the ear (temporal artery)

The ease of palpability of a pulse is dictated by the patient's blood pressure. If his or her systolic blood pressure is below 90 mmHg, the radial pulse will not be palpable. Below 80 mmHg, the brachial pulse will not be palpable. Below 60 mmHg, the carotid pulse will not be palpable. Since systolic blood pressure rarely drops that low, the lack of a carotid pulse usually indicates death. It is not unheard of, however, for patients with certain injuries, illnesses or other medical problems to be conscious and aware with no palpable pulse.hi

See also:

• Haemodynamics
• Heart
• Heart rate
• Physical examination
• Pulsus paradoxus (paradoxical pulse)

Categories: Sign (medicine) | Medical tests

Adapted from the Wikipedia article "Pulse", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki