Physiological Processes and Vital Signs

• Vital signs include body temperature, pulse, respirations, and blood pressure
• These signs should be checked to monitor the functions of the body

Learning Objectives

• Describe the four vital signs.
• Enumerate factors that affect human vital signs.
• Identify the different instruments to measure the vital signs.
• Identify alterations in vitals.
• Perform proper procedure in vital sign monitoring.

Body Temperature

• Body temperature reflects the balance between the heat produced and heat lost from the body.
• It is measured in degrees Celsius.
• Core temperature refers to the temperature of the deep tissues of the body, such as the abdominal or pelvic cavity
• Surface temperature involves the temperature of the skin, subcutaneous tissue, and fat

Factors That Affect Body Heat Production

• BMR (Basal Metabolic Rate) is the rate of energy utilization in the body required to maintain life-sustaining activities such as breathing
• The younger the person the higher the BMR
• Muscle Activity increases BMR
• Thyroxine Output increases the rate of cellular metabolism in a process called chemical thermogenesis
• Epinephrine, Norepinephrine, and Sympathetic Stimulation/Stress Response, these hormones immediately increase the rate of cellular metabolism.

Heat Loss

• Radiation transfers heat from the surface of one object to the surface of another without contact, mostly in the form of infrared rays.
• Conduction transfers heat from one molecule to a molecule of lower temperature.
• Convection is the dispersion of heat by air currents
• Vaporization is the continuous evaporation of moisture from the respiratory tract, mucosa of the mouth, and skin, known as insensible water loss.

Regulation of Body Temperature

• The hypothalamus is responsible for the regulation of body temperature.

Physiologic Processes To Increase Body Temperature

• Shivering increases heat production
• Sweating is inhibited to decrease heat loss
• Vasoconstriction decreases heat loss

Factors That Affect Body Temperature

• Age, persons over 75 years of age are at high risk of hypothermia due to inadequate diet, loss of subcutaneous fat, lack of activity, and decreased thermoregulatory efficiency.
• Body temperature changes throughout the day
• The highest temperature occurs between 4:00 PM and 6:00 PM
• The lowest temperature occurs between 4:00 AM and 6:00 AM
• Strenuous activities can increase body temp to as high as 38.3 to 40 degrees centigrade.
• Hormones, progesterone secretion during ovulation for women increase body temp by about 0.3 to – 0.6 degrees centigrade or 0.5-1 degrees Fahrenheit
• Stimulation of the sympathetic nervous system can increase the production of epinephrine and norepinephrine, thereby increasing metabolic activity and heat production.
• Extremes in environment can affect body temperature.

Alterations in Body Temperature

• Pyrexia/Hyperthermia is fever expressed in lay terms, temperature above the normal range.
• Normal temperature is from 36.5 to 37.5 degrees centigrade or 96.8 to 98.6 degrees Fahrenheit
• Febrile indicates with fever
• Afebrile indicates without fever
• In intermittent pyrexia, temperature fluctuates returning to normal. (malaria)
• In remittent pyrexia, a wide range of temperature fluctuations above 2 oC occurs over a 24 hour period, all of which are above normal
• In relapsing pyrexia, periods of fever are interspersed with acceptable temperature values
• In constant pyrexia, temperature fluctuates minimally but always remains above the temperature range

Hypothermia

• Hypothermia involves a core body temperature below the lower limit of normal

Physiologic Mechanisms of Hypothermia

• Excessive heat loss.
• Inadequate heat production to counteract heat loss.
• Impaired hypothalamic thermoregulation.
• Clinical Manifestations of Hypothermia.
• Decreased body temperature.
• Severe shivering.
• Feelings of cold and chills.
• Pale, cool waxy skin.
• Frostbite.
• Hypotension.
• Decreased urinary output.
• Disorientation.
• Drowsiness progressing to coma.

Assessing Body Temperature

• Oral temperature site is accessible and convenient
• Rectal temperature site is a reliable measurement
• Axillary is a safe and noninvasive temperature site
• Tympanic membrane is a safe noninvasive site, readly accessible, reflecting the core temperature, and is very fast.
• A temporal Artery is a safe and noninvasive temperature site

Types of Thermometer

• Electronic thermometers provide a reading in just 2 to 60 seconds.
• Chemical disposable thermometers such as heat sensitive tape or patches applied to the forehead change their color to indicate temperature
• Temperature Sensitive Tape
• Temporal Artery Thermometers

Temperature Scales

• Temperature is measured in degrees on two scales:
• Centigrade
• Fahrenheit.
• C= (Fahrenheit temp – 32 ) X 5/9
• F = (Celsius temp X 9/5 ) + 32

Pulse

• The pulse is a wave of blood created by the contraction of the left ventricle to the heart
• It represents the stroke volume output or the amount of blood that enters the arteries with each ventricular contraction
• In a healthy person, the pulse reflects the heartbeat, that is, the pulse rate is the same as the number of ventricular contractions of the heart
• CO, or Cardiac Output is the amount of blood pumped into the arteries by the heart
• CO = SV, or Stroke Volume X HR, or Heart Rate
• e.g. 60 ml X 70 = 4220 ml or 4.22 L

Factors That Affect The Pulse

• Age, as age increases pulse rate decreases.
• Gender, after puberty, the average male's pulse rate is slightly lower than the female's.
• Exercise increases pulse rate.
• Fever increases pulse rate due to vasodilation and increased BMR.
• Medications may increase or decrease the pulse rate. (e.g. digoxin decreases; epinephrine increases)
• Hypovolemia - low blood volume
• Stress - sympathetic nervous stimulation increases the overall activity of the heart
• Position Changes
• Pathology - cardiac and oxygenation problems

Pulse Sites

• Temporal
• Carotid
• Apical
• Brachial
• Radial
• Femoral
• Popliteal
• Posterior Tibial
• Pedal (Dorsalis Pedis)

Pulse and Respiration Variations by Age

• Newborn pulse range is 80-180 and respiration is 30-80.
• 1 Year old pulse range is 80-140 and respiration is 20-40.
• 5-8 Years old pulse range is 75-120 and respiration is 15-25.
• 10 Years old pulse range is 50-90 and respiration is 15-25.
• Teen pulse range is 50-90 and respiration is 15-20.
• Adult pulse range is 60-100 and respiration is 12-20.
• Older Adult pulse range is 60-100 and respiration is 15-20.

Assessing The Pulse

• It is commonly assessed by palpation or auscultation
• Palpate all sites with the 3 middle fingertips except for the apical pulse
• Check for any medication taken
• Ask for current/past activity performed

Assess the Pulse

• Rate (tachycardic or bradycardic?)
• Rhythm (regular or with dysrhythmia/arrhythmia?)
• Volume (it can range from absent to bounding)
• Arterial wall elasticity, a normal artery feels straight, smooth, soft and pliable
• Presence or absence of equality between sides - indicates a disparity with the two sides of the body

Pulse Deficit

• Apical pulse is greater than peripheral pulse. This occurs when some heart contractions are too weak to produce a palpable pulse at the radial site

Respirations

• Respirations is the act of breathing (inhalation and exhalation)
• The Respiratory center is located in the medulla oblongata and the pons of the brain

Breathing Types

• In costal (thoracic) breathing, the muscles move the chest
• In diaphragmatic (abdominal) breathing, there is movement in the abdomen
• Inspiration lasts 1 to 1.5 seconds
• Expiration lasts 2 to 3 seconds

Assessing Respiration

• Assess for the rate, rhythm, and depth of breath
• The RR is normally described as breaths per minute.
• Bradypnea is abnormally slow respiration.
• Tachypnea/Polypnea are is abnormally fast respiration.
• Eupnea indicates breathing is normal in rate and depth.
• Apnea is the absence of breathing.

Factors That Affect Respiration

• Exercise
• Stress
• Increased Environmental Temperature
• Lowered Oxygen Concentration
• In Hypoventilation is the overexpansion of the lungs characterized by very deep, rapid respiration.
• In Hypoventilation, there is underexpansion of the lungs characterized by very shallow respiration

Breathing Patterns

• Rate
• Tachypnea
• Bradypnea
• Apnea
• Rhythm
• Regular
• Irregular

Breathing

• Biot's
• Kussmaul
• Cheyne-Stokes

Breathing Volume

• Hypoventilation
• Hyperventilation

Breathing Ease

• Dyspnea
• Orthopnea

Blood Pressure

• Blood pressuremeasures the pressure exerted by the blood as it flows through the arteries
• The range is between 90-140 mmHg/ 60-90 mmHg
• Systolic Pressure is the pressure of the blood as a result of the contraction of the ventricles
• Diastolic Pressure is the pressure when the ventricles are at rest
• Pulse Pressure is the difference between the diastolic and systolic pressure
• Normal pulse pressure is around 40mmHg or even 100mmHg during exercise
• Consistent high pulse pressure occurs in arteriosclerosis and decreased pulse pressure occurs in severe heart failure

Blood Pressure Determinants

• Pumping Action of the Heart
• Weak pumping action decreases Cardiac Output, decreasing Blood Pressure
• Peripheral Vascular Resistance
• The diameter of the arterioles and capillaries greatly determines resistance
• The smaller the space within the vessel the greater the resistance
• Atherosclerosis is the formation of plaque in the arteries
• Arteriosclerosis is when the arterial vessel walls stiffen

Blood Volume

• Decreased blood volume decreases blood pressure
• Increased blood volume increases blood pressure

Blood Viscosity

• Blood viscosity, the blood becomes viscous when the proportion of RBC in the plasma is high

Factors That Affect Blood Pressure

• Age
• Exercise
• Stress stimulation of the sympathetic nervous system, increases Cardiac Output, or CO and vasoconstriction thereby increasing Blood Pressure
• Gender
• Medications
• Obesity
• Diurnal Variations or daily happenings can affect a typical blood pressure value
• Disease Process: a patient's condition affecting the CO, blood volume, blood viscosity, compliance of the arteries
  • Any of these factors can easily affect Blood Pressure

Hypotension

• Hypotension indicates a blood pressure below normal limits
• It may be caused by analgesics, bleeding, severe burns, and dehydration

Orthostatic Hypotension

• Place a patient in supine position for 10 minutes
• Record the client's pulse rate and blood pressure
• Assist the client to slowly sit or stand Immediately recheck the blood pressure and pulse rate

Assessing Blood Pressure

• Materials Needed:
• Blood pressure cuff
• Sphygmomanometer
• Stethoscope

Blood Pressure Site

• Upper arm
• Thigh
• Korotkoff sounds

Explore the physiological processes involved in heat transfer, metabolic rate, and body temperature regulation. Understand the effects of muscle activity and thyroxine on basal metabolic rate and body temperature. Review methods for assessing vital signs, including temperature and cardiac output, and their clinical significance.