7.2 How to Perform Vital Signs

Sites and Methods

Common methods of temperature measurement in the hospital setting include oral, tympanic membrane, axillary, and rectal routes. It is important to document the route used to obtain a patient’s temperature because of normal variations in temperature in different locations of the body.

Selecting the correct method to take a temperature is also important (Table 7.2). For children 5 years of age and under, the most accurate choice for taking a temperature is rectally; however, as most children do not like to have their temperature taken this way, it can also be done via tympanic or axillary routes. Tympanic temperatures are the most accurate after rectal/core temperatures. Since oral temperatures require cooperation from the patient, they are usually indicated for patients over 5 years of age.

Oral Temperature

To take an oral temperature, obtain an oral thermometer. These come in many designs and sizes, depending on your practice location (Figure 7.6). Oral temperature is reliable when it is obtained close to the sublingual artery.

Figure 7.6 (a) Oral thermometers come in many shapes and sizes, depending on your practice location. (b) Devices can have blue coloring, indicating it is an oral or axillary thermometer, as opposed to a rectal thermometer that has red coloring. (credit (a): Digital Medical Thermometer, Adoric Rectal and Oral Thermometer for Adults and Babies, Thermometer for Fever - Accurate and Fast Readings with Fever Indicator” by Jefferson William/Flickr, CC BY 2.0) (credit (b): “Oral Thermometer” by Chippewa Valley Technical College, CC BY 4.0)

Follow these steps to take an oral temperature:

1. Wash your hands before any patient interaction, and ensure use of proper personal protective equipment (PPE) as required. Gloves are the standard when working with patients; however, if the patient requires additional PPE, such as masks or gowns, don the additional appropriate PPE as required. Ensure there is a probe cover for the oral thermometer if the thermometer is reusable.
2. Ask the patient to open their mouth and place the thermometer in the posterior sublingual pocket under the tongue, slightly off-center (Figure 7.7).
3. Ask the patient to keep the thermometer under their tongue with their mouth closed and refrain from moving it around. Leave the thermometer in place for as long as is indicated by the device manufacturer. The thermometer typically beeps within a few seconds when the temperature has been taken.

   Figure 7.7 Improperly placing a thermometer in a patient’s mouth can result in inaccurate temperature measurements. By placing an oral thermometer in one of the “hot pockets” under the tongue, you can obtain a more accurate reading. (credit: “Frenulum linguae” by Wikimedia Commons, CC BY 3.0)
4. Remove the thermometer, and read the digital display of the results. Discard the probe cover in the garbage (without touching the cover), clean the device according to facility policy, and place the probe back into the device, if appropriate.

Patient Conversations

Assessing Temperature

Scenario: Corrine is a nurse on a medical-surgical floor, and she is preparing to discharge her 45-year-old adult patient, Anna. While she is preparing the paperwork, Anna puts on her call light. Corrine goes to the room.

Patient: I’m suddenly freezing cold, and I’m shivering! What is the temperature in here?

Nurse: [checks thermostat] It’s 73°F (22.8°C) in here, but it has been that way as long as you have been here. How are you feeling?

Patient: I don’t know. Besides cold, I guess I just don’t feel good. Just kind of icky.

Nurse: Let me take your temperature. [Gets the oral thermometer, sees that the temperature is 104°F (40°C). Corrine looks at her patient and sees she looks a bit more flushed than usual, but she also knows the patient would have many other symptoms if this was a true temperature, so she determines further assessment is needed.] Have you had anything to eat or drink since I was last in here?

Patient: Not really. Well, when I started feeling cold, I drank some of my hot tea to try and warm up. I’m still really cold though.

Nurse: Ah okay. Your oral temperature was quite high, but that’s probably because of the tea. Let me take your temperature from a different site. [She gets the tympanic thermometer and checks Anna’s temperature in her ear.] Ah. Your temperature is 101.3°F (38.5°C), so it looks like you may have a bit of a fever. Let me grab you a warm blanket, and then I will call your provider.

Scenario follow-up: Corrine knows that while tympanic temperatures are not as accurate as oral or core temperatures, the fact Anna has a fever correlates with her feeling chilled; thus, even though the oral temperature was inaccurate, she knows an intervention is still required. She provides the blanket for patient comfort while contacting the doctor.

Some factors can cause an inaccurate measurement using the oral route. For example, if the patient recently consumed a hot or cold food or beverage, chewed gum, or smoked prior to measurement, a falsely elevated or decreased reading may be obtained. Oral temperature should be taken fifteen to twenty-five minutes following consumption of a hot or cold beverage or food, or five minutes after chewing gum or smoking.

Tympanic Temperature

The tympanic temperature is typically 32.5°F to 33.1°F (0.3°C–0.6°C) higher than an oral temperature. It is an accurate measurement because the tympanic membrane shares the same vascular artery that perfuses the hypothalamus (the part of the brain that regulates the body’s temperature). The tympanic method should not be used if the patient has a suspected ear infection.

Obtain the appropriate thermometer to take tympanic (ear) temperature. These thermometers also come in many shapes and sizes, depending on your practice location (Figure 7.8).

Figure 7.8 Tympanic thermometers can be used for adult patients and pediatric patients 2 years of age and older. (credit: “Tympanic thermometer” by BCcampus, CC BY 4.0)

Follow these steps to obtain a tympanic temperature:

1. Wash your hands before any patient interaction. Don appropriate PPE.
2. Remove the tympanic thermometer from its holder, and place a probe cover on the thermometer tip without touching the probe cover with your hands. Turn the device on.
3. Ask the patient to keep their head still. For an adult or older child, gently pull the helix (outer ear) up and back to visualize the ear canal. For an infant or child under age 3 years, gently pull the helix down. Insert the probe just inside the ear canal, but never force the thermometer into the ear. The device will beep within a few seconds after the temperature is measured (Figure 7.9).

   Figure 7.9 Taking a tympanic temperature accurately entails gently using the pinna of the ear to open the ear canal, thus getting a better read on the tympanic membrane. (credit: modification of “Taking tympanic temperature” by BCcampus, CC BY 4.0)
4. Remove the thermometer, and read the results displayed. Discard the probe cover in the garbage (without touching the cover), clean the device according to facility policy, and then place the device back into the holder.

Rectal Temperature

Measuring rectal temperature is an invasive method. Some sources suggest its use only when other methods are not appropriate. However, when measuring infant temperature, it is considered a gold standard because of its accuracy. The rectal temperature is usually 33.8°F (1ºC) higher than the oral temperature. A rectal thermometer has red coloring to distinguish it from an oral or axillary thermometer (Figure 7.11). Thermometers that are specified for rectal use only should not be used to take any other type of temperature.

Figure 7.11 Thermometers specified for rectal use only are generally colored red and/or labeled for rectal use only. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Follow these steps to take a rectal temperature:

1. Before taking a rectal temperature, ensure the patient’s privacy. Wash your hands and put on gloves and any other PPE as necessary.
2. For infants, place them in a supine position and raise their legs upward toward their chest. Parents may also be encouraged to hold the infant across their lap, face down, to decrease movement and provide a sense of safety (Figure 7.12).

   Figure 7.12 Rectal temperatures can be taken in either of these positions for an infant or child under the age of 2 years. (a) In this position, the infant is placed on their back with the nurse holding their legs up. (b) Alternatively, the infant can be placed stomach down on the nurse’s lap. Rectal thermometers should be clearly marked that they are for rectal use only and should not be used for any other route. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)
3. When taking a rectal temperature in older children and adults, assist them into a side-lying position (Figure 7.13) and explain the procedure.

   Figure 7.13 When taking a rectal temperature in adults, bending one or both of the knees better exposes the anus and anatomically aligns the rectum for ease of inserting the temperature probe. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)
4. Remove the probe from the device and place a probe cover on the thermometer. Lubricate the cover with a water-based lubricant, and then gently insert the probe ½ to 1 in (1.3 to 2.5 cm) inside the anus, depending on the patient’s size. Remove the probe when the device beeps.
5. Read the result and then discard the probe cover in the trash can without touching it. Assist the patient with redressing/covering up, as appropriate. Disinfect the device as indicated by facility policy. Remove your gloves, wash your hands, and store the thermometer in a designated place to ensure it will be only for rectal use.

Taking rectal temperatures may not be the standard of practice in acute care or inpatient settings. In general, a specific order is required in inpatient/acute care settings for measuring rectal temperatures. Rectal temperatures are contraindicated in many patient situations, ranging from disease states, such as leukemia, to whether the patient is on certain medications such as blood thinners. Moreover, if the patient cannot be positioned in such a way to take a rectal temperature, this method is contraindicated as well.

Normal Temperature Ranges

Normal temperature ranges can vary across the life span and can vary among individuals. When working in an inpatient or acute care facility, be sure to check facility policy for specific parameters on what defines a fever. See Table 7.3 for normal temperature ranges for various routes.

Sites and Methods

While assessing a pulse, place two fingers on the pulse point. It is important to use your index and middle fingers to assess pulses; your own thumb has a pulse and may interfere with your assessment. Also, the index and middle fingers can easily access almost any pulse point. Pulse is created by the force of blood being pumped through the aorta from the left ventricle. This force manifests as a regular throb at a specific spot under the skin, called a pulse point, where the artery is close to the surface. Press down with your fingers until you can feel the pulsation, but not so forcefully that you are obliterating the wave of the force passing through the artery. Somewhere between light and firm is the best way to check a pulse, and then wait to feel the beat under your fingers.

With palpation, pulse is assessed by feeling with fingers. Palpation is the most frequently used method of assessing pulse, as it is readily available to do and can be done quickly if there is a critical need. Sites at which to obtain pulse measurements include the radial artery (pulse point located at each wrist below the base of the thumb), carotid artery (pulse point located on each side of the neck lateral to and above the trachea), popliteal artery (pulse point located behind both knees), femoral artery (pulse point located in the groin), brachial artery (pulse point located on each side of the upper arm on the medial aspect superior to the antecubital fossa), posterior tibial artery (pulse point located posterior to the medial aspect of the ankle), and dorsalis pedis artery (pulse point located roughly atop both feet). These common sites and methods of obtaining pulse measurements are listed in Table 7.4.

Location	Illustration	Explanation
Radial artery (wrist)	Figure 7.15 (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)	Place the index and middle fingers where the thumb meets the wrist to assess the radial pulse. Note that radial pulses are difficult to palpate on newborns and children under the age of 5 years, so the brachial or apical pulses are typically obtained in this population.
Carotid artery (neck)	Figure 7.16 (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)	Place the index and middle fingers laterally on one side or the other of the trachea, taking special care not to press too hard to occlude blood flow or cause discomfort to the trachea. The carotid pulse is typically palpated during medical emergencies because it is the last pulse to disappear when the heart is not pumping an adequate amount of blood.
Popliteal artery (behind the knee)	Figure 7.17 (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license) Figure 7.18 (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)	With the knee slightly bent, place the index and middle fingers on the medial aspect of the back of the knee. This can also be done with both hands to palpate both the medial and lateral aspects of the knee.
Femoral artery (groin)	Figure 7.19 (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)	With the patient lying supine and relaxed, place the index and middle finger in the middle of the crease where the leg joins the anterior abdomen.
Brachial artery (upper inner arm)	Figure 7.20 (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)	With the patient sitting upright or lying in bed, place the index and middle finger on the medial aspect of the upper arm superior to the antecubital fossa; this also is the place where the bladder of the blood pressure cuff is placed when taking a blood pressure. A brachial pulse is typically assessed in infants and children because it can be difficult to feel the radial pulse in these populations. If needed, a Doppler ultrasound device can be used to obtain the pulse.
Posterior tibial artery (behind the ankle bones)	Figure 7.21 (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)	This is easiest to feel when the patient is lying supine. Place the index and middle fingers posterior to the ankle bones.
Dorsalis pedis artery (top of the foot)	Figure 7.22 (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)	This is best done with the patient lying supine. Place two fingers on the top of the foot; often this pulse is located more medially, superior to the great toe.

Table 7.4 Pulse Points

Sometimes, however, pulses cannot be palpated. This can be due to many reasons, such as trauma to the body or patient disease states, such as cardiovascular disease or peripheral artery disease. If a pulse is absent, a doppler ultrasound device is typically used to verify perfusion of the limbs. A Doppler is a handheld device that allows the examiner to hear the whooshing sound of the pulse. This device is also commonly used when assessing peripheral pulses in the lower extremities, such as the dorsalis pedis pulse or the posterior tibial pulse. Using a Doppler still requires the nurse to be able to identify the anatomical locations of pulses and to know which pulses are best to use in a given situation.

Follow these steps to use a Doppler to auscultate pulses:

1. Obtain a Doppler machine. Wash hands before any patient interaction. Don gloves and any other appropriate PPE necessary.
2. Locate the desired pulse to assess. Apply a small amount of medical-grade ultrasound gel to the desired pulse site.
3. Turn on the Doppler, and place it atop the gel. Gently press on the Doppler probe; as with manual palpation, do not press so hard as to occlude the artery, but do not place the probe so lightly as to not be able to assess the pulse.
4. Listen for a pulsing “whoosh” sound to know if the pulse has been located. Ensure that the sound heard is pulsing; a continuous “whoosh” indicates the Doppler has located a vein and not an artery. Once the pulse is correctly located, assess as if palpating for sixty seconds (or thirty seconds and multiply by two).
5. Wipe down the patient’s skin to clean off the ultrasound jelly; also wipe down the Doppler machine and clean with an alcohol wipe or according to facility policy.

Normal Pulse Ranges

The normal adult pulse rate (heart rate) at rest is 60 to 100 bpm with different ranges according to age (Table 7.5). It is important to consider each patient’s situation when analyzing if their pulse rate is within normal range. Begin by reviewing their documented baseline pulse rate. Consider other factors if the pulse is elevated, such as the presence of pain or crying in an infant. It is best to document the assessment when a patient is resting and comfortable, but if this is not feasible, document the circumstances surrounding the assessment, and reassess as needed.

Measuring Respirations

The easiest and most time-efficient way to measure respiratory rate is to first tell the patient that you will be assessing their pulse. Not telling the patient their respiratory rate is being measured ensures they do not unconsciously change their respiratory rate. Locate the radial pulse and then observe the patient’s chest rise and fall; if the patient has a regular rate, count each respiration cycle for thirty seconds and multiply by two. If the patient’s respirations are irregular, count each cycle for a full minute. Assessment of respirations also includes auscultating their breaths with a stethoscope. Depending on your practice location, the patient may be sitting up or lying down in bed. The ideal position for assessing respirations is sitting up and a bit forward; this is so gravity can help the lungs be as open as possible. If patient acuity does not allow for this, assessing respirations while supine or lying upright in bed is acceptable.

When obtaining a respiratory rate, the respirations are also assessed for quality, rhythm, and rate. The quality of a person’s breathing is normally relaxed and silent. However, loud breathing, nasal flaring, or the use of accessory muscles in the neck, chest, or intercostal spaces indicates respiratory distress. People experiencing respiratory distress also often move into a tripod position, meaning they are leaning forward and placing their arms or elbows on their knees or on a bedside table. If a patient is demonstrating new signs of respiratory distress as you are obtaining their vital signs, it is vital to immediately notify the healthcare provider or follow agency protocol. Respirations normally have a regular rhythm in children and adults who are awake. A regular rhythm means that the frequency of the respiration follows an even tempo with equal intervals between each respiration. However, newborns and infants commonly exhibit an irregular respiratory rhythm.

Normal Respiratory Rate Ranges

Like all other vital signs, the normal respiratory rate is different based on the patient’s age. In infancy, the normal rate is 30 to 53 breaths per minute. This decreases to 22 to 37 breaths per minute for toddlers, and 18 to 25 breaths per minute for school-age children. Then from adolescence through adulthood, the normal rate is 12 to 20 breaths per minute. Changes from these norms can be indicative of disease processes or homeostatic imbalances with the patient, or just as with the other vital signs, it can indicate the effect of external and modifiable factors such as anxiety, fear, or pain. It is important for the nurse to consider the respiratory assessment data in context with the other vital signs and other situational and correlating data obtained from the patient to direct the appropriate course of action.

Normal Oxygen Saturation Ranges

Across the life span, normal oxygen does not vary much; a healthy individual should have an SpO₂ reading between 95 and 100 percent, regardless of age. For patients with chronic respiratory conditions, such as COPD, the target range for SpO₂ is often lower at 88 to 92 percent. Although SpO₂ is an efficient, noninvasive method to assess a patient’s oxygenation status, it is an estimate and is not always accurate. For example, if a patient is severely anemic and has a decreased level of hemoglobin in the blood, the SpO₂ reading is affected. Decreased peripheral circulation can also cause a misleading low SpO₂ level.

In practice, the nurse should be sure to check with the provider to familiarize themselves with the patient’s baseline SpO₂ and ensure the proper orders are in place that outline the amount of oxygen a patient should get according to their disease state. Oxygen is a drug like any other medication, and a person can be given too little or too much. Nurses are licensed to apply oxygen as necessary in an emergency situation and can obtain an order from the healthcare provider after the fact. Some facilities may have standing orders based on vital sign readings.

Sites and Methods

To assess blood pressure, place the patient in a relaxed reclining or sitting position. The patient should be seated quietly for at least five minutes in a chair prior to blood pressure measurement. Ask the patient which arm they prefer to use. Be aware of conditions that contraindicate the use of an arm for blood pressure measurement, such as a previous mastectomy or the presence of a fistula. During the procedure, both feet should be on the floor, and the arm should be supported at heart level. Adapt the procedure to life-span considerations of the patient, as appropriate. There are four main methods to assessing blood pressure:

1. To take a manual blood pressure reading, a stethoscope and a sphygmomanometer (manual blood pressure cuff) are used. This method entails placing the bell (smaller side) or diaphragm (larger side) of the stethoscope on the brachial artery and compressing the artery with the blood pressure cuff. The following are completed to obtain a manual blood pressure:
   1. Gather the proper equipment: a sphygmomanometer, a stethoscope, and an appropriately sized blood pressure cuff. The cuff’s bladder should encircle 80 to 100 percent of the patient’s arm circumference (AHA, 2023). Wash your hands and don gloves (if necessary) before any patient interaction. Don any appropriate PPE as required per patient situation and facility guidelines.
   2. Remove or rearrange the patient’s clothing so the cuff and the stethoscope are on bare skin.
   3. Center the bladder of the blood pressure cuff over the brachial artery with the lower margin 1 in above the antecubital space. Fit the cuff evenly and snugly. Palpate the brachial artery in the antecubital space.
   4. Locate the radial pulse.
   5. Close the valve on the air bulb and inflate the cuff rapidly (while palpating the radial or brachial pulse) to the level at which pulsations are no longer felt.
   6. With the eartips of the stethoscope placed downward and forward, place the bell/diaphragm lightly on the brachial artery and rapidly inflate the cuff to thirty points above where the brachial or radial pulse is no longer felt.
   7. Deflate the cuff gradually at a constant rate by slightly opening the valve on the bulb (2 to 3 mm Hg/second) until the first Korotkoff (pulse) sound is heard. Note the systolic pressure.
   8. Continue to deflate the cuff slowly at 2 mm Hg/second. Note the point at which Korotkoff sounds disappear completely as the diastolic pressure.
   9. Deflate the cuff completely and remove the patient’s arm from the cuff.
   10. Inform the patient of the blood pressure reading.
   11. Cleanse all equipment as per facility policy.
       See Figure 7.25 for a visual of all the elements discussed.

       Figure 7.25 Measuring blood pressure manually entails obtaining the right cuff and placing the cuff in the right place over the brachial artery. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)
2. Electric or automatic blood pressure is taken using an electric cuff/blood pressure machine; no stethoscope is required. The cuff is placed around the patient’s upper arm, and the machine automatically compresses the artery and measures the blood pressure (Figure 7.26). As with a manual pressure, ensure the patient is properly positioned sitting upright with back and arm supported and legs uncrossed.

   Figure 7.26 Using an automatic blood pressure machine does not require a stethoscope but still requires a properly sized blood pressure cuff for accuracy. (credit: modification of “Automatic blood pressure cuff” by BCcampus, CC BY 4.0)
3. In some patient situations, a manual or automatic blood pressure cannot be obtained. The patient could be critically ill and not have peripheral pulses to measure a blood pressure, or they could have a type of heart failure that requires an artificial implant to circulate their blood called a left ventricular assist device. In these special cases, a doppler blood pressure is obtained.
   The procedure to obtain a Doppler blood pressure is similar to that used to obtain a manual or automatic blood pressure. The peripheral pulse is located and auscultated, and the properly sized blood pressure cuff is identified and placed. The cuff is inflated until the pulse on the Doppler machine can no longer be heard, and then the cuff is released, just as with a manual pressure. The number on the sphygmomanometer that correlates with the return of the Doppler pulse sound is the systolic blood pressure; no diastolic pressure is measured with this method.
4. Arterial pressure monitoring may be utilized in some situations where the patient is critically ill and needs continuous pressure monitoring, other methods of blood pressure monitoring are impractical, or the patient needs frequent arterial blood sampling (Saugel et al., 2020). An arterial line is a thin, hollow, flexible tube that is placed into a peripheral artery (often in the wrist or groin). In arterial pressure monitoring, an invasive measurement, a catheter is placed inside the patient’s body. The arterial line is connected to a transducer via a rigid fluid-filled tubing that converts the data to display on a monitor as arterial waveforms during heartbeats as well as numerical pressures (Nguyen & Bora, 2023).
   This method provides real-time, continuous information about the cardiovascular system (Figure 7.27). These constant measurements help the providers make care decisions such as medication selection and titration when these patients are critically ill. It is also a highly complicated method that requires proper skill in selecting the correct catheter site, choosing the correct catheter, leveling and zeroing the transducer, and monitoring the quality of the blood pressure waveform (Saugel et al., 2020).

   Figure 7.27 An arterial line blood pressure monitoring setup requires specialized knowledge not only to insert the tube but also to properly calibrate the pressure tubing in order for the machine to yield accurate blood pressure measurements. (attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Normal Blood Pressure Ranges

Abnormal blood pressure readings can signify an area of concern and a need for intervention. Normal adult blood pressure should be less than 120/80 mm Hg. The medical term for elevated blood pressure readings of 130/80 mm Hg or higher is hypertension. See Table 7.6 for blood pressure categories according to the 2017 American College of Cardiology and American Heart Association Blood Pressure Guidelines (Welton et al., 2018). Prior to diagnosing a person with hypertension, the healthcare provider will calculate an average blood pressure based on two or more blood pressure readings obtained on two or more occasions.

The medical term for low blood pressure readings less than 90/60 mm Hg is hypotension. Hypotension can be caused by dehydration, bleeding, cardiac conditions, and the side effects of many medications. Hypotension can be of significant concern because of the potential lack of perfusion to critical organs when blood pressures are low. A drop in blood pressure that occurs when moving from a lying down (supine) or seated position to a standing (upright) position is orthostatic hypotension. When measuring blood pressure, orthostatic hypotension is defined as a decrease in blood pressure by at least 20 mm Hg systolic or 10 mm Hg diastolic within three minutes of standing. When a person stands, gravity moves blood from the upper body to the lower limbs. As a result, there is a temporary reduction in the amount of blood in the upper body for the heart to pump, which decreases blood pressure. Normally, the body quickly counteracts the force of gravity and maintains stable blood pressure and blood flow. In most people, this transient drop in blood pressure goes unnoticed. However, some patients with orthostatic hypotension can experience lightheadedness, dizziness, or fainting. This is a significant safety concern because of the increased risk of falls and injury, particularly in older adults.