LEARNING OBJECTIVES	PROCEDURES
Temperature
1. Define a vital sign. 2. Explain the reasons for taking vital signs. 3. Explain how body temperature is maintained. 4. List examples of how heat is produced in the body. 5. List examples of how heat is lost from the body. 6. State the normal body temperature range and the average body temperature. 7. List and explain factors that can cause variation in the body temperature. 8. List and describe the three stages of a fever. 9. List the sites for taking body temperature, and explain why these sites are used.	Measure oral body temperature. Measure axillary body temperature. Measure rectal body temperature. Measure aural body temperature. Measure temporal artery body temperature.
Pulse
10. Explain the mechanism of pulse. 11. List and explain the factors that affect the pulse rate. 12. Identify a specific use for each of the eight pulse sites. 13. State the normal range of pulse rate for each age group. 14. Explain the difference between pulse rhythm and pulse volume.	Measure radial pulse. Measure apical pulse.
Respiration
15. Explain the purpose of respiration. 16. State what occurs during inhalation and exhalation. 17. State the normal respiratory rate for each age group. 18. List and explain the factors that affect the respiratory rate. 19. Explain the difference between rhythm and depth of respiration. 20. Describe the character of each of the following abnormal breath sounds: crackles, rhonchi, wheezes, and pleural friction rub.	Measure respiration.
Pulse Oximetry
21. Explain the purpose of pulse oximetry. 22. State the normal oxygen saturation level of a healthy individual. 23. List and describe the functions of the controls, indicators, and displays on a pulse oximeter. 24. Describe the difference between a reusable and a disposable oximeter probe. 25. List and describe factors that may interfere with an accurate pulse oximetry reading.	Perform pulse oximetry.
Blood Pressure
26. Define blood pressure. 27. State the normal range of blood pressure for an adult. 28. List and describe factors that affect the blood pressure. 29. Identify the different parts of a stethoscope and a sphygmomanometer. 30. Identify the Korotkoff sounds. 31. State the advantages and disadvantages of an automated oscillometric blood pressure device. 32. Explain how to prevent errors in blood pressure measurement.	Measure blood pressure. Determine systolic pressure by palpation.

Introduction to Vital Signs

Vital signs are objective guideposts that provide data to determine a person’s state of health. Vital signs include temperature, pulse, respiration (collectively called TPR), and blood pressure (BP). Another indicator of a patient’s health status is pulse oximetry. Although some physicians order this measurement routinely on all patients as part of the patient workup, most physicians order this vital sign only when the patient complains of respiratory problems (e.g., shortness of breath).

The normal ranges of the vital signs are finely adjusted, and any deviation from normal may indicate disease. During the course of an illness, variations in the vital signs may occur. The medical assistant should be alert to any significant changes and report them to the physician because they indicate a change in the patient’s condition. When patients visit the medical office, vital signs are routinely checked to establish each patient’s usual state of health and to establish baseline measurements against which future measurements can be compared. The medical assistant should have a thorough knowledge of the vital signs and should attain proficiency in taking them to ensure accurate findings.

General guidelines that the medical assistant should follow when measuring the vital signs are as follows:

1. Be familiar with the normal ranges for all vital signs. Keep in mind that normal ranges vary based on the different age groups (infant, child, adult, elder).

2. Make sure that all equipment for measuring vital signs is in proper working condition to ensure accurate findings.

3. Eliminate or minimize factors that affect the vital signs, such as exercise, food and beverage consumption, smoking, and emotional state.

4. Use an organized approach when measuring the vital signs. If all of the vital signs are ordered, they are usually measured starting with temperature, followed by pulse, respiration, blood pressure, and pulse oximetry.

Temperature

Regulation of Body Temperature

Body temperature is maintained within a fairly constant range by the hypothalamus, which is located in the brain. The hypothalamus functions as the body’s thermostat. It normally allows the body temperature to vary by only about 1° to 2° Fahrenheit (F) throughout the day.

Body temperature is maintained through a balance of the heat produced in the body and the heat lost from the body (Figure 19-1). A constant temperature range must be maintained for the body to function properly. When minor changes in the temperature of the body occur, the hypothalamus senses this and makes adjustments as necessary to ensure that the body temperature stays within a normal and safe range. If an individual is playing tennis on a hot day, the body’s heat-cooling mechanism is activated to remove excess heat from the body through perspiration.

Figure 19-1 Body temperature represents a balance between the heat produced in the body and the heat lost from the body.

Table 19-1

Equivalent Fahrenheit and Celsius Temperatures

Fahrenheit	Celsius
93.2	34
95	35
96.8	36
97.7	36.5
98.6	37
99.5	37.5
100.4	38
101.3	38.5
102.2	39
104	40
105.8	41
107.6	42
109.4	43
111.2	44
Temperature Conversion
1. Celsius to Fahrenheit: To convert Celsius to Fahrenheit, multiply by and add 32: °F=°C×9/5+32 2. Fahrenheit to Celsius: To convert Fahrenheit to Celsius, subtract 32 and multiply by: °C×°F−32×5/9

From Bonewit-West K: Clinical procedures for medical assistants, ed 8, St Louis, 2011, Saunders.

Alterations in Body Temperature

A body temperature greater than 100.4° F (38° C) indicates a fever, or pyrexia. If the body temperature falls between 99° F (37.2° C) and 100.4° F (38° C), this is called a low-grade fever. When an individual has a fever, the heat the body is producing is greater than the heat the body is losing. A temperature reading greater than 105.8° F (41° C) is known as hyperpyrexia. Hyperpyrexia is a serious condition, and a temperature greater than 109.4° F (43° C) is generally fatal.

A body temperature less than 97° F (36.1° C) is classified as subnormal, or hypothermia. This means that the heat the body is losing is greater than the heat it is producing. A person usually cannot survive with a temperature less than 93.2° F (34° C). Terms used to describe alterations in body temperature are illustrated in Figure 19-3.

Figure 19-3 Terms that describe alterations in body temperature (adult oral temperature).

Variations in Body Temperature

During the day-to-day activities of an individual, normal fluctuations occur in the body temperature. The body temperature rarely stays the same throughout the course of a day. The medical assistant should take the following points into consideration when evaluating a patient’s temperature.

1. Age. Infants and young children normally have a higher body temperature than adults because their thermoregulatory system is not yet fully established. Elderly individuals usually have a lower body temperature owing to factors such as loss of subcutaneous fat, lack of exercise, and loss of thermoregulatory control. Table 19-2 shows the normal ranges of body temperature according to age group.

Table 19-2

Variations in Body Temperature by Age

Age	Site	Average Temperature
Newborn	Axillary	97° F-100° F	36.1° C-37.8° C
1 yr	Oral	99.7° F	37.6° C
5 yr	Oral	98.6° F	37° C
Adult	Oral	98.6° F	37° C
	Rectal	99.6° F	37.5° C
	Axillary	97.6° F	36.4° C
	Aural	98.6° F	37° C
Elderly (over 70 yr)	Oral	96.8° F	36° C

From Bonewit-West K: Clinical procedures for medical assistants, ed 8, St Louis, 2011, Saunders.

2. Diurnal variations. During sleep, body metabolism slows down, as do muscle contractions. The body’s temperature is lowest in the morning before metabolism and muscle contractions begin increasing.

3. Emotional states. Strong emotions, such as crying and extreme anger, can increase the body temperature. This is important to consider when working with young children, who frequently cry during examination procedures or when they are ill.

4. Environment. Cold weather tends to decrease the body temperature, whereas hot weather increases it.

5. Exercise. Vigorous physical exercise causes an increase in voluntary muscle contractions, which elevates the body temperature.

6. Patient’s normal body temperature. Some patients normally run a low or high temperature. The medical assistant should review the patient’s past vital sign recordings.

7. Pregnancy. Cell metabolism increases during pregnancy, and this elevates body temperature.

Fever

Fever, or pyrexia, denotes that a patient’s temperature has increased to greater than 100.4° F (38° C). An individual who has a fever is said to be febrile; one who does not have a fever is afebrile.

Fever is a common symptom of illness, particularly inflammation and infection. When there is an infection in the body, the invading pathogen functions as a pyrogen, which is any substance that produces fever. Pyrogens reset the hypothalamus, causing the body temperature to increase to above normal. Fever is not an illness itself, but rather a sign that the body may have an infection. Most fevers are self-limited, that is, the body temperature returns to normal after the disease process is complete.

Stages of a Fever

A fever can be divided into the following three stages:

1. The onset is when the temperature first begins to increase. This increase may be slow or sudden, the patient often experiences coldness and chills, and the pulse and respiratory rate increase.

2. During the course of a fever, the temperature rises and falls in one of the following three fever patterns: continuous, intermittent, or remittent. Fever patterns are described and illustrated in Table 19-3. During this stage the patient has an increased pulse and respiratory rate and feels warm to the touch. The patient also may experience one or more of the following: flushed appearance, increased thirst, loss of appetite, headache, and malaise. Malaise refers to a vague sense of body discomfort, weakness, and fatigue.

Table 19-3

Fever Patterns

Pattern	Description	Illustration
Continuous fever	Body temperature fluctuates minimally but always remains elevated. Occurs with: Scarlet fever Pneumococcal pneumonia
Intermittent fever	Body temperature alternately rises and falls and at times returns to normal or becomes subnormal. Occurs with: Bacterial infections Viral infections
Remittent fever	Wide range of temperature fluctuations occur, all of which are above normal. Occurs with: Influenza Pneumonia Endocarditis

From Bonewit-West K: Clinical procedures for medical assistants, ed 8, St Louis, 2011, Saunders.

3. During the subsiding stage, the temperature returns to normal. It can return to normal gradually or suddenly (known as a crisis). As the body temperature is returning to normal, the patient usually perspires and may become dehydrated.

Assessment of Body Temperature

Assessment Sites

There are five sites for measuring body temperature: mouth, axilla, rectum, ear, and forehead. The locations in which temperatures are taken should have an abundant blood supply so that the temperature of the entire body is obtained, not the temperature of only a part of the body. In addition, the site must be as closed as possible to prevent air currents from interfering with the temperature reading. The site chosen for measuring a patient’s temperature depends on the patient’s age, condition, and state of consciousness; the type of thermometer available; and the medical office policy.

Highlight on Fever

Although most fevers indicate an infection, not all do. Noninfectious causes of fever include heatstroke, drug hypersensitivity, neoplasms, and central nervous system damage.

A fever usually is not harmful if it remains less than 102° F (38.9° C). Research suggests that fever may serve as a defense mechanism to destroy pathogens that are unable to survive above the normal body temperature range.

The level of the fever is not related to the seriousness of the infection. A patient with a temperature of 104° F (40° C) may not be any sicker than a patient with a temperature of 102° F (38.9° C).

In children, fever often is one of the first signs of illness and has a tendency to become highly elevated. In contrast, in elderly patients, fever may be elevated to only 1° F to 2° F above normal, even with a severe infection.

During a fever, the body’s basal metabolism increases by 7% for each degree of temperature elevation. Heart and respiratory rates also increase to meet this metabolic demand.

Chills during a fever result when the hypothalamus has been reset at a higher temperature. In an attempt to reach this temperature, involuntary muscle contractions (chills) occur, which produce heat, causing the temperature of the body to increase. After the higher temperature has been reached, the chills subside, and the individual then feels warm.

Increased perspiration during a fever occurs when the hypothalamus has been reset at a lower temperature, for example, after taking an antipyretic or after the cause of the fever has been removed. To cool the body and reach this lower temperature, the body perspires, often profusely; profuse perspiration is known as diaphoresis.

Putting It All Into Practice

My name is Sergio Martinez, and I am a registered medical assistant. I work in a large clinic that is associated with a medical school. At present, I work in the family medicine department, but I also have worked in dermatology and internal medicine. Family medicine is the area I enjoy most because of the wide variety of tasks that are performed. There is rarely a dull moment.

I focus primarily on clinical medical assisting. Taking vital signs is a big part of my job responsibilities. It is routine at my clinic to take height, weight, temperature, pulse, respiration, and blood pressure on every patient seen at the clinic, no matter what the reason for his or her visit. I assist the physician with various procedures, examinations, and minor office surgery, and I administer injections, run electrocardiograms, and perform various laboratory tests.

Taking vital signs and length and weight on small children can be very challenging at times. Some children start to cry as soon as they are put on the scale. Taking a temperature on an uncooperative toddler can be very difficult. I try to calm the child as much as possible, and for good behavior, I give a lot of praise. Stickers also are a great reward for cooperative behavior. Usually when small children learn that they can trust you, they are not as frightened by the experience. It is rewarding when a child learns not to be afraid of being evaluated for routine vital signs.

Oral Temperature

The oral method is a convenient and one of the most common means for measuring body temperature. When the medical assistant records a temperature, the physician assumes it has been taken through the oral route, unless it is otherwise noted. There is a rich blood supply under the tongue in the area on either side of the frenulum linguae. The thermometer should be placed in this area to receive the most accurate reading. The patient must keep the mouth closed during the procedure to provide a closed space for the thermometer.

Axillary Temperature

Axillary temperature is recommended as a site for measuring temperature in toddlers and preschoolers. The axillary site also should be used for mouth-breathing patients and for patients with oral inflammation or who have had oral surgery.

The temperature obtained through the axillary method measures approximately 1° F lower than the same person’s temperature taken through the oral route (see Table 19-2). The medical assistant should make a notation to tell the physician that the temperature was taken through the axillary route.

Rectal Temperature

The rectal temperature provides an extremely accurate measurement of body temperature because few factors can alter the results. The rectum is highly vascular and, of the five sites, provides the most closed cavity. The temperature obtained through the rectal route measures approximately 1° F higher than the same person’s temperature taken through the oral route (see Table 19-2). The medical assistant should make a notation on the patient’s chart if the temperature has been taken rectally.

The rectal method is generally used for infants and young children, unconscious patients, and mouth-breathing patients, and when greater accuracy in body temperature is desired. The rectal site should not be used with newborns because of the danger of rectal trauma.

Aural Temperature

The aural (ear) site is used with the tympanic membrane thermometer. The ear provides a closed cavity that is easily accessible. Tympanic membrane thermometers provide instantaneous results, are easy to use, and are comfortable for the patient. They make it easier to measure the temperature of children younger than 6 years, uncooperative patients, and patients who are unable to have their temperatures taken orally.

Forehead Temperature

The temporal artery is a major artery of the head that runs laterally across the forehead and down the side of the neck. In the area of the forehead, it is located approximately 2 mm below the surface of the skin. Because the temporal artery is located so close to the skin surface and is easily accessible, the forehead provides an ideal site for obtaining a body temperature measurement. In addition, the temporal artery has a constant steady flow of blood, which assists in providing an accurate measurement of the patient’s body temperature.

The forehead site can be used to measure body temperature using a temporal artery thermometer in individuals of all ages (newborns, infants, children, adults, elderly). The results compare in accuracy with other methods used to measure body temperature. The temperature obtained through the forehead site is about the same as a rectal temperature measurement. The temporal artery reading measures approximately 1° higher than oral body temperature and 2° higher than axillary temperature on the Fahrenheit scale.

Types of Thermometers

The four types of thermometers available for measuring body temperature are electronic thermometers, tympanic membrane thermometers, temporal artery thermometers, and chemical thermometers. Mercury glass thermometers are no longer used in the medical office because they break easily and release mercury. Mercury is a chemical that is dangerous to the human body because it can cause damage to the nervous system. If mercury is released into the environment, it can be harmful to wildlife. Many cities have banned the sale or use of mercury because of its potential hazards.

Electronic Thermometer

An electronic thermometer is often used in the medical office to measure body temperature. Electronic thermometers are portable and measure oral, axillary, and rectal temperatures ranging from 84° F to 108° F (28.9° C to 42.2° C).

An electronic thermometer measures body temperature in a brief time, which varies between 4 and 20 seconds, depending on the brand of thermometer used. The temperature results are digitally displayed on an LCD screen. An electronic thermometer consists of interchangeable oral and rectal probes attached to a battery-operated portable unit (Figure 19-4). The probes are color-coded for ease in identifying them. The oral probe is color-coded with blue on its collar and is used to take oral and axillary temperatures; the rectal probe is color-coded with red on its collar and is used to take rectal temperatures only.

A disposable plastic cover is placed over the probe to prevent the transmission of microorganisms among patients. Depending on the method of taking the temperature, the probe may be inserted into the mouth, axilla, or rectum and is left in place until an audible tone is emitted from the thermometer. When the tone sounds, the patient’s temperature in degrees Fahrenheit is displayed on the screen. The medical assistant ejects the plastic probe cover into a regular waste container.

The casing, probes, and attached cords of the electronic thermometer should be periodically cleaned with a soft cloth slightly dampened with a solution of warm water and a disinfectant cleaner.

Procedures 19-1, 19-2, and 19-3 outline the methods for measuring oral, axillary, and rectal temperatures using an electronic thermometer.

Procedure 19-1 Measuring Oral Body Temperature—Electronic Thermometer

Outcome

Measure oral body temperature.

Equipment/Supplies

• Electronic thermometer

• Oral probe (blue collar)

• Plastic probe cover

• Waste container

1. Procedural Step. Sanitize your hands, and assemble the equipment.

2. Procedural Step. Remove the thermometer unit from its storage base, and attach the oral (blue collar) probe to it. This is accomplished by inserting the latching plug (at the end of the coiled cord of the oral probe) to the plug receptacle on the thermometer unit until it clicks into place. Insert the probe into the face of the thermometer.

Principle. The oral probe is color-coded with a blue collar for ease in identifying it.

3. Procedural Step. Greet the patient and introduce yourself. Identify the patient and explain the procedure. If the patient has recently ingested hot or cold food or beverages or has been smoking, you must wait 15 to 30 minutes before taking the temperature.

Principle. Ingestion of hot or cold food or beverages and smoking change the temperature of the mouth, which could result in an inaccurate reading.

4. Procedural Step. Grasp the probe by the collar, and remove it from the face of the thermometer. Slide the probe into a disposable plastic probe cover until it locks into place.

Principle. Removing the probe from the thermometer automatically turns on the thermometer. The probe cover prevents the transfer of microorganisms from one patient to another.

5. Procedural Step. Take the patient’s temperature by inserting the probe under the patient’s tongue in the pocket located on either side of the frenulum linguae. Instruct the patient to keep the mouth closed.

Principle. There is a good blood supply in the tissue under the tongue. The mouth must be kept closed to prevent cooler air from entering and affecting the temperature reading.

6. Procedural Step. Hold the probe in place until you hear the tone. At that time, the patient’s temperature appears as a digital display on the screen. Make a mental note of the temperature reading. (The temperature indicated on this thermometer is 98.2° F [36.8° C]).

7. Procedural Step. Remove the probe from the patient’s mouth. Discard the probe cover by firmly pressing the ejection button while holding the probe over a regular waste container. Do not allow your fingers to come in contact with the probe cover.

Principle. The probe cover should not be touched so as to prevent the transfer of microorganisms from the patient to the medical assistant. Saliva is not considered regulated medical waste; the probe can be discarded in a regular waste container.

8. Procedural Step. Return the probe to its stored position in the thermometer unit. Return the thermometer unit to its storage base.

Principle. Returning the probe to the unit automatically turns off and resets the thermometer.

9. Procedural Step. Sanitize your hands, and chart the results. Include the date, the time, and the temperature reading.

Principle. Patient data must be recorded properly to aid the physician in the diagnosis and to provide future reference.

Procedure 19-2 Measuring Axillary Body Temperature— Electronic Thermometer

Outcome

Measure axillary body temperature. NOTE: Many of the principles for taking a temperature already have been stated and are not included in this procedure.

Equipment/Supplies

• Electronic thermometer

• Oral probe (blue collar)

• Plastic probe cover

• Waste container

1. Procedural Step. Sanitize your hands, and assemble the equipment.

2. Procedural Step. Remove the thermometer unit from its storage base, and attach the oral (blue collar) probe to it. This is accomplished by inserting the latching plug (on the end of the coiled cord of the oral probe) to the plug receptacle on the thermometer unit until it locks into place. Insert the probe into the face of the thermometer.

3. Procedural Step. Greet the patient and introduce yourself. Identify the patient and explain the procedure.

4. Procedural Step. Remove clothing from the patient’s shoulder and arm. Ensure that the axilla is dry. If it is wet, pat it dry with a paper towel or a gauze pad.

Principle. Clothing removal provides optimal exposure of the axilla for proper placement of the thermometer. Rubbing the axilla causes an increase in the temperature in that area owing to friction, resulting in an inaccurate temperature reading.

5. Procedural Step. Grasp the probe by the collar, and remove it from the face of the thermometer. Slide the probe into a disposable probe cover until it locks into place.

6. Procedural Step. Take the patient’s temperature by placing the probe in the center of the patient’s axilla. Instruct the patient to hold the arm close to the body. Hold the arm in place for small children and other patients who cannot maintain the position themselves.

Principle. Interference from outside air currents is reduced when the arm is held in the proper position.

7. Procedural Step. Hold the probe in place until you hear the tone. At that time, the patient’s temperature appears as a digital display on the screen. Make a mental note of the temperature reading.

8. Procedural Step. Remove the probe from the patient’s axilla. Discard the probe cover by firmly pressing the ejection button while holding the probe over a regular waste container. Do not allow your fingers to come in contact with the probe cover.

9. Procedural Step. Return the probe to its stored position in the thermometer unit. Return the thermometer unit to its storage base.

10. Procedural Step. Sanitize your hands, and chart the results. Include the date, the time, and the axillary temperature reading. The symbol must be charted next to the temperature reading to tell the physician that an axillary reading was taken.

Procedure 19-3 Measuring Rectal Body Temperature— Electronic Thermometer

Outcome

Measure rectal body temperature.

Equipment/Supplies

• Electronic thermometer

• Rectal probe (red collar)

• Plastic probe cover

1. Procedural Step. Sanitize your hands, and assemble the equipment.

2. Procedural Step. Remove the thermometer unit from its storage base. Attach the rectal (red collar) probe to it. This is accomplished by inserting the latching plug (on the end of the coiled cord of the rectal probe) to the plug receptacle on the thermometer unit. Insert the probe into the face of the thermometer.

Principle. The rectal probe is color-coded with a red collar for ease in identifying it.

3. Procedural Step. Greet the patient and introduce yourself. Identify the patient and explain the procedure. If a patient is a child or an adult, provide him or her with a patient gown. Instruct the patient to remove enough clothing to provide access to the anal area and to put on the gown with the opening in the back. If the patient is an infant, ask the parent to remove his or her diaper.

Principle. It is important to explain what you will be doing, because body temperature may be higher in a fearful or apprehensive patient. The patient gown provides the patient with modesty and comfort.

4. Procedural Step. Apply gloves. Position the patient. Adults and children: Position the patient in the Sims position, and drape the patient to expose only the anal area. Infants: Position the infant on his or her abdomen.

Principle. Gloves protect the medical assistant from microorganisms in the anal area and feces. Correct positioning allows clear viewing of the anal opening and provides for proper insertion of the thermometer. Draping reduces patient embarrassment and provides warmth.

5. Procedural Step. Grasp the probe by the collar, and remove it from the face of the thermometer. Slide the probe into a disposable plastic probe cover until it locks into place. Apply a lubricant to the tip of the probe cover up to a level of 1 inch.

Principle. A lubricated thermometer can be inserted more easily and does not irritate the delicate rectal mucosa.

6. Procedural Step. Instruct the patient to lie still. Separate the buttocks to expose the anal opening, and gently insert the thermometer probe approximately 1 inch into the rectum of an adult, inch in children, and inch in infants. Do not force insertion of the probe. Hold the probe in place until the temperature registers.

Principle. The probe must be inserted correctly to prevent injury to the tissue of the anal opening. The probe should be held in place to prevent damage to the rectal mucosa.

8. Procedural Step. Gently remove the probe from the rectum in the same direction as it was inserted. Avoid touching the probe cover. Discard the probe cover by firmly pressing the ejection button while holding the probe over a regular waste container. Return the probe to its stored position in the thermometer unit. Return the thermometer unit to its storage base.

Principle. Fecal material is not considered regulated medical waste; the probe can be discarded in a regular waste container.

9. Procedural Step. Wipe the patient’s anal area with tissues to remove excess lubricant. Dispose of the tissues in a regular waste container.

Principle. Wiping the anal area makes the patient more comfortable.

10. Procedural Step. Remove gloves, and sanitize your hands. Chart the results. Include the date, the time, and the rectal temperature reading. The symbol must be charted next to the temperature reading to tell the physician that a rectal reading was taken.

Tympanic Membrane Thermometer

The tympanic membrane thermometer is used at the aural site. The tympanic membrane thermometer functions by detecting thermal energy that is naturally radiated from the body. As with the rest of the body, the tympanic membrane gives off heat waves known as infrared waves. The tympanic thermometer functions like a camera by taking a “picture” of these infrared waves, which are considered a documented indicator of body temperature (Figure 19-5). The thermometer calculates the body temperature from the energy generated by the waves and converts it to an oral or rectal equivalent.

The tympanic membrane thermometer is battery operated and consists of a small handheld device with a sensor probe (Figure 19-6). To operate the thermometer, the probe is covered with a disposable soft plastic cover and is placed in the outer third of the external ear canal. An activation button is depressed momentarily, and the results are displayed in 1 to 2 seconds on a digital screen. The probe cover is ejected into a regular waste container. The procedure for taking aural body temperature using a tympanic membrane thermometer is presented in Procedure 19-4.

Procedure 19-4 Measuring Aural Body Temperature—Tympanic Membrane Thermometer