CHAPTER 26 / Vital Sign Assessment 3
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CHAPTER 26 VITAL SIGN ASSESSMENT CRITICAL THINKING CHALLENGE KEY TERMS CRITICAL THINKING CHALLENGE apnea couple in their 50s is shopping in a mall, where a health fair is set up. You are a nurse auscultatory gap participating at a booth offering blood pressure readings. After much coaxing, the A woman persuades her husband to have his blood pressure taken. You obtain a read- blood pressure ing of 168/94 mm Hg. The wife reacts strongly, saying, “I told you that your lack of exercise bradycardia and overeating would catch up with you one day. How am I going to manage being a widow at such an early age?” The husband responds by saying, “Don’t worry about me. I’m bradypnea just as healthy as ever, and I plan to live until I’m 99 years old. I’m sure there’s something core temperature wrong with that machine.” Both of them turn to you. The wife says, “Tell him it’s not the machine and that he isn’t taking care of himself!” diastolic blood pressure Once you have completed this chapter and have incorporated vital signs into your knowledge dyspnea base, review the above scenario and reflect on the following areas of Critical Thinking: eupnea 1. Identify possible interpretations of an isolated blood pressure reading of 168/94 mm Hg. List factors that may have affected the reading’s accuracy. hypertension 2. Analyze the man’s reaction to this situation. Indicate the teaching points about blood hypotension pressure that may be appropriate at this time. 3. Outline potential ways to deal therapeutically with the wife’s anxiety, describing possible Korotkoff sounds verbal and nonverbal interactions. orthostatic hypotension paradoxical blood pressure LEARNING OBJECTIVES prehypertension pulse deficit Upon completion of this chapter, the student will be able to do the following: 1. Describe the procedures used to assess the vital signs: temperature, pulse, respirations, pulse pressure and blood pressure. stroke volume 2. Describe factors that can influence each vital sign. 3. Identify equipment routinely used to assess vital signs. systolic blood pressure 4. Identify rationales for each route of temperature assessment. tachycardia 5. Identify the location of commonly assessed pulse sites. 6. Describe how to assess orthostatic hypotension. tachypnea 7. Recognize normal vital sign values among various age groups. tidal volume 1 2 UNIT 5 / Essential Assessment Components ital signs—body temperature (T), pulse (P), respirations ature can vary widely with environmental conditions and (R), and blood pressure (BP)—indicate the function of physical activity. Despite these fluctuations, the temperature V some of the body’s homeostatic mechanisms. Measure- inside the body, the core temperature, remains relatively con- ment and interpretation of the vital signs are important compo- stant, unless the client develops a febrile illness. The body’s nents of assessment that can yield information about underlying cells, tissues, and organs require this constant internal temper- health status. Client teaching concerning the vital signs is a key ature and function optimally within a relatively narrow tem- aspect of health promotion. perature range. Typical or normal ranges of values for vital signs have been Normal body temperature when measured orally usually established for clients of various age groups (Table 26-1). Dur- ranges between 36.5° and 37.5°C (97.6° and 99.6°F). This state ing initial measurement of a client’s vital signs, the values are of normal body temperature in a client is termed afebrile. When compared with these normal ranges to determine any variation temperature exceeds 37.5°C, this is termed pyrexia. Body tem- that might indicate illness. When several sets of vital signs have perature can fluctuate with exercise, changes in hormone levels, been obtained, this information forms a baseline for comparison changes in metabolic rate, and extremes of external temperature. of subsequent measurements. Isolated vital sign values are less In general, rectal temperatures may be 1° higher than oral tem- helpful; a series of values should be taken and evaluated to estab- peratures and axillary temperatures 1° lower than oral tempera- lish trends for the client. Vital sign trends that deviate from nor- tures (Sund-Levander, Grodzinsky, Loyd, & Wahren, 2004). mal are much more significant than isolated abnormal values. Tympanic temperatures fall approximately midway between The tasks involved in measuring vital signs are simple and normal oral and rectal temperature measurements. Refer to easy to learn, but interpreting the measurements and incorpo- Table 26-2, which lists normal adult temperatures at different rating them into ongoing care and assessment require knowl- body sites. edge, problem-solving skills, critical thinking, and experience. Although measuring vital signs are usually part of routine care, Regulation of Body Temperature they provide valuable information and their evaluation should Body temperature regulation requires the coordination of many not be taken lightly. body systems. For the core temperature to remain steady, heat The frequency with which to assess vital signs should be indi- production must equal heat loss. The hypothalamus, located in vidualized for each client. Healthy people may have vital signs the pituitary gland in the brain, is the body’s built-in thermo- checked only during annual physical examinations. Clients seen stat. It can sense small changes in body temperature and stimu- in ambulatory settings, wellness clinics, or psychiatric institutions lates the necessary responses in the nervous system, circulatory may require infrequent vital sign checks. Most inpatient settings system, skin, and sweat glands to maintain homeostasis (state of have a policy regarding the frequency of vital sign assessment, dynamic equilibrium). minimally every 8 hours for stable clients. Physicians order addi- tional vital sign checks at specific intervals based on the client’s Heat Production condition (e.g. postoperatively or after an invasive diagnostic pro- cedure). The nurse caring for the client may decide to monitor The body continually produces heat as a byproduct of chemical vital signs more frequently if the client’s condition changes. reactions that occur in body cells. This collective process is known as metabolism. The process of thermoregulation keeps core tem- perature fairly constant regardless of where the heat is being pro- BODY TEMPERATURE duced. The basal metabolic rate (BMR) is the amount of energy the body uses, and thus the amount of heat produced, during Humans are warm-blooded creatures, which means they main- absolute rest in an awake state. Physical exercise, increased pro- tain a consistent internal body temperature independent of duction of thyroid hormones, and stimulation of the sympathetic the outside environment. The body’s surface or skin temper- nervous system can increase heat production. TABLE 26-1 NORMAL VITAL SIGN RANGES ACROSS THE LIFESPAN Temperature Blood Pressure (mm Hg) Pulse Respirations (°F) Systolic Diastolic Newborn (>96 h) 70–190 30–60 96–99.5 60–90 20–60 Infant (>1 mo) 80–160 30–60 99.4–99.7 74–100 50–70 Toddler 80–130 24–40 99–99.7 80–112 50–80 Preschooler 80–120 22–34 98.6–99 82–110 50–78 School-age 75–110 18–30 98–98.6 84–120 54–80 Adolescent 60– 90 12–20 97–99 94–120 62–80 Adult 60–100 12–20 97–99 90–120 60–80 Older adult (>70 yr) 60–100 12–20 95–99 90–120 60–80 CHAPTER 26 / Vital Sign Assessment 3 person’s body temperature can vary by as much as 2°C (3.6°F) TABLE 26-2 NORMAL ADULT TEMPERATURE from early morning to late afternoon. Theorists attribute this RANGES FROM DIFFERENT variation to changes in muscle activity and digestive processes, BODY SITES which are usually lowest in the early morning during sleep. Even greater variation in body temperature at various times of the day Oral Axillary Rectal Tympanic is found in infants and children. 97.6°–99.6°F 96.6°–98.6°F 98.6°–100.6°F 98.2°–100.2°F Although researchers have established no absolute relation- ° ° ° ° ° ° ° ° 36.5 –37.5 C 35.8 –37.0 C 37.0 –38.1 C 36.8 –37.9 C ship between circadian rhythm and body temperature, 95% of From Braun, S., Preston, P., & Smith, R. (1998). Getting a better read on clients have their maximum temperature elevation around thermometry. RN, 61(3), 60. 6 PM. A study by Beaudry et al. (1996) suggests once-a-day fever screening of afebrile clients at 6 PM. This would ease bur- dens on staff time and limit the disruption of sleeping clients Heat Loss during the night. Just as the body is continually producing heat, it is also contin- Exercise uously losing heat. Heat is lost through four processes: radia- Body temperature increases with exercise because exercise tion, conduction, convection, and evaporation. increases the breakdown of carbohydrates and fats to provide Exposure to a cold environment increases radiant heat loss. energy. Strenuous exercise, such as running a marathon, can All objects with temperatures above absolute zero constantly temporarily raise the temperature to as high as 40°C (104°F). lose heat through infrared heat rays. Covering the body with Stress closely woven, dark fabric can reduce radiant heat loss. Emotional or physical stress can elevate body temperature. When Conduction is the transfer of heat from one object to another. stress stimulates the sympathetic nervous system, circulating The body loses a considerable amount of heat to the air through levels of epinephrine and norepinephrine increase. As a result, conduction. It can also lose heat to water during swimming or the metabolic rate increases, which, in turn, increases heat pro- tepid baths. Convection is the loss of heat through air currents duction. Stressed or anxious clients may have an elevated tem- such as from a breeze or a fan.