15.5 Heart Rate

Pulse Locations

Pulse locations are anatomical places on the body where the pulse should be readily palpable because of the artery’s proximity to the surface of the skin (Figure 15.23). The most frequent locations for detecting pulses are over the radial, temporal, and carotid arteries.

The most common pulse location is the radial pulse. This pulse is found on the distal lateral forearm. The radial pulse is the preferred site to obtain a pulse for routine vital signs.

Figure 15.23 The pulse is most readily measured at the radial artery but can be measured at any of the pulse points shown. (credit: modification of work from Anatomy and Physiology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

The temporal pulse site is located on either side of the forehead. The carotid pulse is located on the anterior neck on both sides of the trachea. This is the location of large arteries that branch off the aorta and are the main blood supply to the brain. When a nurse must check the carotid pulse, only one side should be assessed at a time to not restrict blood flow to the brain. This pulse location, due to its size, is often checked in emergency situations to verify the presence or absence of a pulse.

The apical pulse is auscultated directly using a stethoscope. It is located at the fifth intercostal space, midclavicular line on the anterior chest wall. The apical pulse is counted for one full minute when obtaining routine vital signs. Certain populations need the apical pulse auscultated rather than palpating the peripheral pulse. For example, the heart rate should be auscultated in patients receiving digoxin, a medication that affects the heart rate and contraction, and those with an irregular rate or rhythm. As a nurse, if the peripheral pulse requires further investigation, for example, too weak to be felt or too fast to be counted, listening to the apical pulse is a good way to validate results.

The brachial pulse is found in the inner antecubital space and is used when obtaining blood pressure. The stethoscope is placed over this artery to listen to blood flow in the arteries. In infants, the brachial pulse is felt in the inner upper arm and is the preferred upper extremity peripheral pulse site in this age group. It is used in emergency situations to determine the presence or absence of a pulse in infants since the carotid pulse is difficult to quickly locate.

The femoral pulse is found in the groin. The femoral artery is a large artery that provides blood flow to the lower extremities. This femoral pulse is the preferred lower extremity pulse site in infants.

There are several other pulse locations in the lower extremities. One such pulse site is the popliteal pulse, found behind the knee. Other lower extremity pulses are the posterior tibial pulse, located behind the inner ankle, and the dorsalis pedis pulse, commonly called the pedal pulse, which is located on the dorsal aspect of the foot. The dorsalis pedis pulse is the preferred lower extremity peripheral pulse site in adults and children.

When obtaining routine vital signs on an adult, the nurse should assess the radial pulse. However, sometimes this location might not be the optimal pulse location. The radial pulse is not always available to be assessed. For example, the patient may have an arterial line inserted or a cast or bandage may be covering the site. Amputation may also have occurred. In cases where the radial pulse is inaccessible, the nurse should auscultate to obtain the apical pulse. The apical pulse should be listened to for a full minute to determine the heart rate, and the brachial and femoral pulses should be palpated to assess peripheral perfusion. Palpation of the pulse is a direct representation of blood volume and flow. A weak, thready pulse may be due to reduced cardiac blood flow such as with dehydration or heart disease.

Pulse Characteristics

When obtaining the pulse, or heart rate, the nurse is also assessing characteristics such as rhythm, depth, and quality. Characteristics of the pulse provide information about the predictability and efficiency of the heart and the quality of the blood vessels. For instance, the heart may be strong and healthy, but if the blood vessels are occluded, the pulse will feel weak or even absent. The nurse needs to note the rhythm, depth, and quality of the pulse to ensure the health of the cardiovascular system.

Factors Affecting Pulse Rates

Normal and healthy fluctuations can occur, and they affect pulse rate. Exercise, particularly aerobics, increases pulse rate. Sleep, conversely, decreases the pulse. Emotions also affect the heart rate. Intense fear and anxiety increase the pulse rate, while relaxation lowers it.

Pulse rate abnormalities also occur because of physical conditions. Conditions that increase metabolism, such as a fever and hyperthyroidism, will also increase the pulse rate. A lack of oxygen will also increase pulse rate. A lack of oxygen can occur as a result of a variety of pulmonary complications. Without enough oxygen, body tissues are unable to be perfused, or receive the oxygen needed to function. The body then feeds this information back to the brain, which signals the heart to then attempt to resolve by increasing the heart rate. When circulating blood volume is decreased, heart rate will also increase to compensate for the lack of perfusion.

Cardiac abnormalities will also affect pulse rate. Structural problems with the heart may lead to an increased pulse rate since the efficacy of the heart contraction is generally weakened. Heart failure, which may result from structural cardiac anomalies or lifestyle, may also increase heart rate. The heart is unable to contract effectively, which, in turn, causes the heart rate to compensate to aid in maintaining cardiac output. Electrical abnormalities in the heart will lead to a host of cardiac arrythmias, which affect not only pulse rate but also the rhythm.