In medicine, a person's pulse is the throbbing of their arteries. It can be felt in any place that allows for an artery to be compressed against a bone, such as at the neck (carotid artery), at the wrist (radial artery), behind the knee (popliteal artery), on the inside of the elbow (brachial artery), and near the ankle joint (posterior tibial artery). The pulse rate can also be measured by measuring the heart beats directly (the apical pulse).
Pressure waves move the artery walls, which are pliable; these waves are 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 pronounced but relatively slow-moving (3–6 m/s). As it travels towards the peripheral blood vessels, it gradually diminishes and becomes faster. In the large arterial branches, its velocity is 7–10 m/s; in the small arteries, it is 15–35 m/s. The pressure pulse is transmitted fifteen or more times more rapidly than the blood flow.
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 too 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 60 to 100 beats per minute (BPM), although well-conditioned athletes may have a healthy pulse rate lower than 60 BPM. Bradycardia occurs when the pulse rate is below 60 per minute, whereas tachycardia occurs when the rate is above 100 BPM. During sleep, the pulse can drop to as low as 40 BPM; during strenuous exercise, it can rise as high as 150–200 BPM. Generally, pulse rates are higher in infants and young children. The resting heart rate for an infant is usually close to an adult's pulse rate during strenuous exercise (average 110 BPM for an infant).
A collapsing pulse is a sign of hyperdynamic circulation.
The ease of palpability of a pulse is dictated by the patient's blood pressure. If his or her systolic blood pressure is below 80 mmHg, the radial pulse will not be palpable. Below 70 mmHg, the brachial pulse will not be palpable. Below 60 mmHg, the carotid pulse will not be palpable. However, a study by the National Institutes of Health indicated that this method was not accurate enough and often overestimated a patient's systolic blood pressure. The lack of a palpable carotid pulse is often an indication of death.
Pulses are manually palpated with fingers. 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 the thumb must be placed near an artery and pressed gently against a firm structure, usually a bone, in order to feel the pulse.
Make sure the person is calm and has been resting for 5 minutes before reading the pulse. Put the index and middle fingers over the pulse count, and count for 30 seconds, and afterwards multiply by 2, to get the pulse rate. If the person's pulse rate is irregular, count for a full minute, and do not multiply. Averaging multiple readings may give a more representative figure.
Home blood pressure measurement devices also typically give a pulse reading.