Pulse Evaluation

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.
Pulsus alternans 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. Kussmaul described the condition in 1873
after treating several patients with pericardial effusion. The pulse decreased
during inspiration (and in some cases disappeared). However, the heart was
obviously still beating, so Kussmaul named the condition “der paradoxe Puls”
.
A paradoxial pulse is seen when cardiac output is blocked, as in cardiac
tamponade, but also when lung compliance is decreased, as in COPD. A
blood-pressure apparatus was not yet invented in 1873 (Korotkoff first used
the Riva-Rocci cuff in 1905) and a link between pulse and blood pressure
was not made until Gauchat and Katz at Western Reserve University did so
in 1924. Thus, although pulsus paradoxus currently is considered a blood
pressure sign, it is actually a pulse sign . In a busy emergency setting where nuances
of change in blood-pressure readings are difficult to detect, reversion to
Kussmaul’s palpation of an artery is more useful. As an example, in the trauma
setting when a penetrating injury to the chest is present, gradual disappearance
of the radial pulse on inspiration may herald an impending cardiac tamponade.
Peripheral Pulses
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)
Practical Points
• Record the rate and rhythm (regular, irregular), as well as the quality
and strength of the pulse (weak, strong, thready). Examples:
1. L radial—54, reg, weak.
2. R femoral—130, irreg, thready.
• Always auscultate the heart and palpate the pulse. The rates may
differ (pulse deficit). Example: HR—120, L radial
• Never be satisfied with one set of vitals.
• In a patient with a possible vascular event, such as a dissecting
thoracic aneurysm, take pulses in all extremities.
• Sometimes in the obese patient and others a radial and brachial
pulse cannot be felt, and one cannot hear a heart beat. If the patient
is comatose, palpate the femoral. It is the easiest to find (in
the elderly the carotid is sometimes stenosed and difficult to find).
Use a Doppler if necessary.
 • Never rely on a monitor or any electronic device for the heart rate.
Murphy’s Law will exert its inexorable effect and although a normal
sinus rhythm will be showing on the monitor the patient will
have no pulse and will be moribund or dead.
• Do not auscultate the heart over clothing.