CHAPTER 21 Measuring Vital Signs

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CHAPTER 21 Measuring Vital Signs
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Five Vital Signs

• Temperature, pulse, respiration, blood pressure,
  and pain
• Vital signs give indications as to the current
  health status of the patient and clues to changes
  in conditions as they occur.
• Knowing age-variable normal values
  andphysiologic regulators are part of the
  assessment process.
• Accurate measurements are an absolute requirement.

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Production of Body Heat

• Heat is a by-product of normal body metabolism
• As metabolism increases, heat increases.
• When the body is invaded by pathogens, the body
  elevates the temperature to elevate the basal
  metabolic rate in an effort to destroy pathogens.

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Factors Affecting Body Heat Production

• Basal metabolic rate (BMR) is affected by the
  thyroid hormone.
• Increased thyroid hormone causes an increase in
  metabolic rate and increased temperature.
• Decreased levels of thyroid hormone result in a
  deceased metabolic rate and a decreased body
  temperature.
• (Contd)

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Factors Affecting Body Heat Production

• (Contd)
• Other hormones affecting metabolic rate
• Epinephrine
• Norepinephrine
• Testosterone
• Men have a higher BMR than women because of
  testosterone.
• Voluntary muscle movement causes increased heat
  production.
• Shivering can increase heat production up to five
  times normal.

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Body Temperature Regulation

• Hypothalamus acts as the thermostat to control
  body temperature.
• Pyrogens may increase the thermostats set point
  (pyrexia).
• A decrease in body temperature results in
  peripheral vasoconstriction and shivering.
• An increase in body temperature results in
  peripheral vasodilatation and diaphoresis.
• (Contd)

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Body Temperature Regulation

• (Contd)
• Heat loss occurs through the skins exposure to
  the environment through
• Radiation
• Conduction
• Convection
• Evaporation
• Heat being lost by evaporation results in 800-mL
  loss of water each day.

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Body Temperature Measurements

• Temperature measurements vary depending on site
  used.
• Rectal temperatures are approximately1 F higher
  than oral temperatures.
• Axillary temperatures are approximately1 F
  lower than oral temperatures.
• Tympanic membrane measurement approximates core
  body temperature.
• (Contd)

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Body Temperature Measurements

• (Contd)
• Other factors affecting temperature measurements
• Time of day
• Environmental temperature
• Age of the patient
• Physical exercise
• Menstrual cycle or stress
• Eating, drinking, mouth-breathing

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Pyrexia

• Temperature higher than 100.2 F
• Pyrexia (fever) occurs when normal regulation
  mechanisms cannot keep up with heat produced by
  the body.
• Pyrogens such as bacteria cause an increased body
  temperature.
• Diaphoresis is excessive sweat production in an
  effort to cool the body.

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Nursing Interventions to Reduce Fever

• Increase patients fluid intake
• Lower room temperature
• Increase the rate of circulating air
• Remove excessive clothing or bed covers
• Control or reduce the amount of body activity
• Provide sponge bath or cooling blanket
• Antipyretics (ASA, acetaminophen)

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Hypothermia

• Body temperature lower than 94 F
• People at risk for hypothermia
• Infants
• Surgical patients in the operating room
• Elderly exposed to cold for prolonged periods
• People exposed to extreme cold weather
• People exposed to cold water immersion

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Pulse

• Pulse is produced by cardiac contractions causing
  a pressure wave against the walls of arteries
• Cardiac contractions are normally initiated by
  the sinoatrial node.
• Each contraction propels 60 to 70 mL of blood
  into the aorta (stroke volume).
• Stroke volume affects pulse character.
• Stroke volume x heart rate Cardiac output
  (approximately 5 L/min for the average adult)
• (Contd)

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Pulse

• (Contd)
• Normally found by palpation or by auscultation
• Strength is determined by force of cardiac
  contraction and circulating volume.
• Rate is affected by fever, pain, hypoxia,
  anxiety, exercise and cardiac disease
• Rate does not normally change with age, but
  arrythmias are common in the elderly.
• (Contd)

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Pulse

• (Contd)
• Common pulse points
• Radial artery in the wrist at the base of the
  thumb
• Temporal artery just in front of the ear
• Carotid artery on the front side of the neck
• Femoral artery in the groin
• Apical pulse over the apex of the heart
• Popliteal pulse just behind the knee
• Pedal pulse

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Factors Affecting Pulse Rate

• Age
• Body build and size
• Blood pressure
• Drugs
• Emotions
• Blood loss
• Exercise
• Increased body temperature
• Pain
• Hypoxia

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Respirations

• An involuntary autonomic function
• Controlled by respiratory center in the pons and
  medulla in the brainstem
• Triggered by increased levels of CO2 or serum
  hydrogen ion concentration or by decreased levels
  of O2
• Organs of respiration
• Nose, pharynx, larynx, trachea, bronchi, lungs
• (Contd)

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Respirations

• (Contd)
• Respiratory center works with feedback
  mechanisms.
• The carotid body receptors alter rate and depth
  of respiration based on CO2 content of the blood.
• O2 and CO2 are diffused across capillaries in the
  lungs to maintain normal O2, CO2 and H levels.

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Terms Used to Describe Respirations

• Eupnea
• Dyspnea
• Tachypnea
• Hyperventilation
• Cheyne-Stokes
• Apnea
• Kussmauls
• Biots

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Terms Used to Describe Noisy Respirations

• Crackles
• Ronchi
• Stertor
• Stridor
• Wheezes

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Blood Pressure

• The pressure exerted on the arterial walls by the
  
• pumping action of the heart
• Affected by the condition of the vascular bed,
  circulating blood volume, and cardiac output
• Changes with aging are normal
• (Contd)

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Blood Pressure

• (Contd)
• Systolic pressure The pressure exerted on the
  arterial wall during cardiac contraction
• Diastolic Pressure The pressure exerted on the
  arterial wall between contractions
• Blood pressure is affected by cardiac output.
• Blood pressure increases with increases in
  circulating blood volume.
• (Contd)

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Blood Pressure

• (Contd)
• If blood volume decreases beyond the vascular
  beds ability to compensate, blood pressure may
  decrease.
• Causes
• Dehydration
• Hemorrhage
• Vasoconstriction and vasodilatation alter blood
  pressure to compensate for changes in circulating
  volume.

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Changes in Vital Signs Occurring with Aging

• Temperature Heat loss may lead to hypothermia in
  the elderly.
• Lower metabolic rate may also result in
  hypothermia in the elderly.
• Respiratory rates may vary with decreases in
  vital capacity in the elderly.
• Systolic and diastolic blood pressure may rise
  with hardening of the arteries.

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Pain

• Pain is recognized by the JCAHO as the fifth
  vital sign.
• Assessment should include
• Location
• Intensity
• Character
• Frequency
• Duration
• Pain should be measured using a standardized pain
  scale.