The pulse reflects the number of times the heart contracts each minute. It is the palpable wave of blood flow used to assess the efficiency of the circulatory system. While the body has several locations where the pulse can be detected, the radial and carotid arteries are the two sites most frequently used for basic assessment. The choice between them is determined by the specific circumstances of the assessment.
Locating and Measuring the Radial Pulse
The radial pulse is located on the thumb side of the wrist, where the radial artery runs close to the surface, positioned over the radius bone. To measure the pulse here, one should use the pads of the index and middle fingers, pressing gently into the groove between the bone and the tendon. It is important to avoid using the thumb, as it has its own prominent pulse which can lead to an inaccurate reading. The pressure applied should be just enough to feel the distinct throbbing of the artery without collapsing the vessel, which would make the pulse disappear.
This peripheral site is the standard choice for routine monitoring in conscious patients. The radial pulse is commonly used during physical examinations or for self-monitoring. Its location makes it a safe, convenient, and non-intrusive method for assessing heart rate and rhythm. The strength and regularity of the pulse felt at this site also offer insights into peripheral blood flow and overall cardiac output.
Locating and Measuring the Carotid Pulse
The carotid pulse is found in the neck, lateral to the trachea and medial to the large sternocleidomastoid muscle. The artery is located by sliding the index and middle fingers into the soft groove on either side of the neck. Since the carotid arteries are major vessels supplying blood directly to the brain, they are considered a more central pulse point.
When palpating this artery, apply only light pressure to avoid stimulating the carotid sinus. Excessive pressure can trigger a reflex that dramatically slows the heart rate, a condition known as vagal stimulation. Never attempt to palpate both carotid arteries simultaneously, as this action risks compromising blood flow to the brain, potentially causing lightheadedness or fainting. The technique requires careful application of pressure on one side only to safely obtain a measurement.
Situational Factors Governing Pulse Site Selection
The decision to use the radial versus the carotid pulse is governed by the patient’s condition and the goal of the assessment. The radial artery is the default choice for routine monitoring, such as during a standard medical check, exercise, or when the patient is calm and stable. Since it is a peripheral artery, its pulse is a good indicator of adequate circulation to the extremities.
The carotid pulse is reserved for emergency situations, particularly when the radial pulse cannot be readily found or felt. In cases of severe shock, massive blood loss, or very low blood pressure, the body naturally shunts blood flow away from the limbs toward vital organs, like the brain and heart. Because the carotid artery is a large, central vessel, it often maintains a detectable pulse longer than the radial artery under conditions of poor perfusion. Therefore, the presence of a carotid pulse is a reliable sign of ongoing central circulation in an unresponsive or critically ill person.
Calculating and Interpreting the Pulse Rate
Once the pulse is located at either site, the rate is determined by counting the number of beats over a specific period. The standard method is to count the beats for 30 seconds and then multiply that number by two to calculate the beats per minute (bpm). For a more accurate reading, especially if the rhythm feels irregular, the pulse should be counted for a full 60 seconds.
In a resting adult, the normal pulse rate falls within the range of 60 to 100 beats per minute. A resting rate consistently above 100 bpm is referred to as tachycardia, indicating the heart is beating too fast. Conversely, a resting rate below 60 bpm is called bradycardia, meaning the heart is beating too slowly.