pulse

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In medicine, a person's pulse is the arterial palpation of a heartbeat.^[1] It can be palpated 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).

Physiology

The pulse is a decidedly low tech/high yield and antiquated term still useful at the bedside in an age of computational analysis of cardiac performance. Claudius Galen (129AD?) was perhaps the first physiologist to describe the pulse. The pulse is an expedient tactile method of determination of Systolic Blood Pressure to a trained observer. Diastolic blood pressure is nonpalpable and unobservable, occuring between heartbeats.

Pressure waves generated by cardiac Systole move the artery walls, which are pliable and compliant. These properties form the basis of Contractility of the heart muscle. Contractility is measured in many variables, one example being dP/dt representing a robust mathematical argument for cardiac Compliance.

These waves are not caused by the forward movement of the blood itself, however. When the heart contracts, blood is ejected into the aortic and pulmonary vascular beds. At this point, the wave of distention (pulse wave) is pronounced but relatively slow-moving (3–6 m/s (9.8–20 ft/s)). A Pressure gradient force (driven by blood rather than air) is enabled by the contraction of the myocardium. 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 (23–33 ft/s); in the small arteries, it is 15–35 m/s (49–110 ft/s). The pressure pulse is transmitted fifteen or more times more rapidly than the blood flow.

The term pulse is also used to denote the time frequency of the heart beat, usually measured in beats per minute.^[2] In healthy people, the pulse is an accurate measure of heart rate. Under certain pathologic circumstances, including arrhythmias, some of the heart beats are rendered ineffective, and the aorta is not stretched enough to create a palpable pressure wave.

The heart rate can be (much) higher than the pulse rate depending upon the cause or etiolgy. In this case, the heart rate is 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) is determined by simultaneous palpation at the radial artery and auscultation at the heart apex.

Velocity, pulse deficits and much more physiologic data is readily and simplistically visualized by the use of one or more Arterial Catheter s connected to a Transducer. This invasive technique has been commonly used in Intensive Care since the 1970s.

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 or BPM.

Ranges

A normal pulse rate for a healthy adult, while resting, can range from 60 to 80 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 but is only usually symptomatic when below 50BPM, 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).

Evaluation

A collapsing pulse is a sign of hyperdynamic circulation.

Several pulse patterns can be of clinical significance. These include:

• Pulsus alternans
• Pulsus bigeminus
• Pulsus bisferiens
• Pulsus tardus et parvus
• Pulsus paradoxus

The strength of the pulse can also be reported:^[3][4]

• 0 = Absent
• 1 = Barely palpable
• 2 = Easily palpable
• 3 = Full
• 4 = Aneurysmal or bounding

Common pulse sites

Upper limb

Front of right upper extremity

• Axillary pulse: located inferiorly of the lateral wall of the axilla
• Brachial pulse: located on the inside of the upper arm near the elbow, frequently used in place of carotid pulse in infants (brachial artery)
• Radial pulse: located on the lateral of the wrist (radial artery). It can also be found in the anatomical snuff box.
• Ulnar pulse: located on the medial of the wrist (ulnar artery).

Lower limb

• Femoral pulse: located in the thigh, halfway between the pubic symphysis and anterior superior iliac spine (femoral artery).
• Popliteal pulse: Above the knee in the popliteal nasal, found by holding the bent knee. The patient bends the knee at approximately 124°, 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 on the medial side of the ankle around medial malleolus (posterior tibial artery).

Head/neck

Arteries of the neck.

• Carotid pulse: located in the neck (carotid artery). The carotid artery should be palpated gently and while the patient is sitting or lying down. Stimulating its baroreceptors with low 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. Doing so may limit the flow of blood to the head, possibly leading to fainting or brain ischemia. It can be felt between the anterior border of the sternocleidomastoid muscle, above the hyoid bone and lateral to the thyroid cartilage.
• Facial pulse: located on the mandible (lower jawbone) on a line with the corners of the mouth (facial artery).
• Temporal pulse: located on the temple directly in front of the ear (superficial temporal artery).

Torso

• Apical pulse: located in the 4.5th or 5th left intercostal space, just to the left of the sternum. In contrast with other pulse sites, the apical pulse site is unilateral, and measured not under an artery, but below the heart itself (more specifically, the apex of the heart).

See also

• Pulsus paradoxus
• Heart rate
• Pulse meter

References