Evaluation of the Pulse
Blood forced into the aorta during systole sets up a pressure wave that travels down the arteries. The wave expands arterial walls. The expansion wave is palpated with the fingertips as the pulse. In contrast to the heart rate, where two sounds are heard with each beat, one beat is felt with the pulse.
Palpation is done with the tips of the first two fingers, not the fatty parts, since the digital arteries for each finger anastomose at the fingerpad and using the fatty parts may result in the examiner’s own pulse being recorded.
The heart rate may differ from the pulse rate. This is a pulse deficit, seen in atrial fibrillation and occasionally in premature ventricular contractions.
It occurs in fast rates when some ventricular contractions fail to generate a palpable pulse. One beat is so close to another that the ventricle does not have time to fill and not enough blood is available to produce a pulse wave in the artery. The pulse rate is thus lower than the heart rate. It is discovered when the heart rate is auscultated and the radial pulse is palpated, or when the pulse rate differs from the rate on the cardiac monitor. It is seen in arteries removed from the heart, such as the radial.
Trauma patients and those suspected of having critical conditions such as myocardial infarction, dissecting aortic aneurysm and acute abdominal aneurysm should have pulses assessed in all extremities.
Although various pulse magnitudes and contours exist (i.e., pulsus bigeminus, pulsus bisferiens, Corrigan or water-hammer pulse, etc.), demonstrated by the sphygmograph, the usefulness of these as vital sign parameters is weak. The possible exceptions are pulsus alternans and pulsus paradoxus.
is an alternating weak and strong pulse. It is seen in advanced heart failure.
A paradoxical pulse (pulsus paradoxus)
is an exaggeration of the normal decrease in amplitude of the pulse during inspiration. During inspiration, vessels of the lungs increase in size because of increased negative pressure in the thorax. Blood collects in the lungs, and the stroke volume decreases.
Expiration has the opposite effect. The pulse decreased during inspiration (and in some cases disappeared). However, the heart was obviously still beating, so named the condition “der paradoxe Puls” .
The artery commonly used for pulse-taking is the radial, lying lateral to the flexor carpi radialis tendon on the distal radius. It is sometimes difficult to find.
The second most useful is the brachial, because of blood pressure taking. Its location sometimes surprises people. It is more easily palpable medial, not lateral, to the biceps tendon and superior to, not in, the antecubital fossa (cubital is forearm; antecubital is volar forearm. The differences have become obscured and the two terms are often used synonymously). In the antecubital fossa, the brachial artery divides into the radial and ulnar arteries. The ulnar goes deep and the radial crosses the biceps tendon and runs laterally down the forearm. If the stethoscope is placed in the antecubital fossa, the blood pressure is being measured in the proximal portion of the radial artery, not the brachial. Accurate palpation of the brachial artery alleviates multiple attempts at blood-pressure taking.
The common carotid
artery lies deep and slightly anterior to the sternocleidomastoid muscle. One must be careful to lightly palpate the artery, since sustained pressure will activate the baroreceptor mechanism and slow the heart rate. Do not palpate both carotid arteries at the same time or fainting may occur.
The femoral artery
, the largest of the pulse-taking arteries, is located at the midpoint of the inguinal ligament between the anterior superior iliac spine and the pubic symphysis. It is the more useful for palpation in infants, the obese, the elderly and during cardiopulmonary resuscitation.
The popliteal artery
is the continuation of the femoral at the popliteal fossa. It lies deep and medial to the popliteal vein and tibial nerve and is frequently difficult, if not impossible, to find. Searching for it is unnecessary if good femoral and pedal pulses are present. Popliteal palpation evaluates patency when foot arteries are unavailable.
In the foot, the posterior tibial artery
is the continuation of the popliteal and is sometimes difficult to locate. It lies behind and below the medial malleolus. Often an easier one to find is the dorsal pedis on the dorsum of the foot at the junction of the first two extensor tendons (extensor hallucis longus and brevis—hallus: Latin—great toe). It is helpful to mark the area with an “X” for a difficult-to-find dorsal pedis pulse (or any other).