NSB103 Health Assessment - Introduction to Vital Signs

Introduction to Vital Signs

Learning Outcomes

  • Demonstrate knowledge of body systems' structure and functions.
  • Describe physiological principles behind vital signs: temperature, pulse, respiratory rate, and blood pressure.
  • Explain homeostatic control of core body temperature, blood pressure, and breathing.
  • Apply clinical reasoning to assess and interpret vital signs.
  • Discuss factors affecting body temperature, pulse rate, respiratory rate, and blood pressure.
  • Describe characteristics included in assessing respirations and pulse.
  • Recognize normal age-related variations in vital sign measurements.
  • Communicate biological and health assessment information using appropriate clinical terminology for variations in vital signs.

The Vital Signs and Homeostasis

What are the Vital Signs?

  • Traditional vital signs:
    • Temperature (T)
    • Pulse (P)
    • Respiratory rate (R)
    • Blood pressure (BP)
  • Additional observations:
    • Oxygen saturation (SpO2)
    • Pain
    • Level of consciousness
    • Urine output

Why are These Signs ‘Vital’?

  • Indicators of cardiovascular, respiratory, nervous, and endocrine systems functioning.
  • Disease, infection, trauma can alter/damage homeostatic mechanisms, leading to clinical changes in vital signs.

Reasons for Assessing Vital Signs

  • Establish baseline data.
  • Identify if vital signs are within normal range.
  • Monitor patients at risk for altered vital signs.
  • Early warning of acute physiological deterioration.
  • Evaluate changes in vital signs in response to clinical interventions like therapies and medications.

Why is it Vital That You Assess These Signs?

  • Essential nursing responsibility.
  • Recognizing and responding to deteriorating patients is essential for safe, high-quality care.

Vital Signs and Patient Safety

  • Changes in vital signs can indicate life-threatening clinical states requiring urgent intervention.
  • Strong correlation between increased mortality rates and observations outside normal ranges.
  • Graphs showing prevalence and mortality rates related to:
    • Systolic Blood Pressure
    • Respiratory Rate
    • Heart Rate

TEMPERATURE

  • Body temperature reflects balance between:
    • Heat production (by-product of cell metabolism, especially muscle activity).
    • Heat gain (hot environment).
    • Heat loss (influenced by environmental conditions and body size).
  • Core vs. surface temperature.

Avenues of Heat Gain and Heat Loss from the Body

  • Evaporation from the skin.
  • Convection from the breeze.
  • Radiation from the sun and the ground.
  • Conduction from the ground.

Maintaining Core Body Temperature Homeostasis

Temperature Regulation: When You Get Cold

  • Receptors: Thermoreceptors in the skin and hypothalamus detect decreased body temperature.
  • Control Center: Heat-promoting center in the hypothalamus is activated.
  • Effectors & Response: Blood vessels in the skin constrict, reducing blood flow and minimizing heat loss. Shivering is triggered, generating more heat.
  • Homeostatic Range: As body temperature returns to normal, feedback decreases effector responses.

Temperature Regulation: When You Get Hot

  • Challenge to create a feedback loop describing events to maintain body temperature homeostasis when getting hot.

Factors Affecting Body Temperature

  • Age
  • Time of day
  • Hormones
  • Environment
  • Physical activity or stress
  • Site of temperature measurement

Assessing Body Temperature

  • Common sites:
    • Oral cavity (under the tongue).
    • Axilla.
    • Rectum.
    • Ear (tympanic membrane).
    • Forehead (temporal artery).

Interpreting Temperature Measurements

  • Normal ranges in adults:
    • Tympanic: 35.4 - 37.4 °C
    • Axillary: 36.0 - 38.0 °C
    • Oral: 36.7 - 38.0 °C
    • Rectal: Depends if calibrated to oral or rectal
  • Normal values in children are similar to adults.
  • Body temperature in the elderly is often 1°C lower.

Interpreting Temperature Measurements

  • Abnormal temperatures:
    • Hypothermia: < 35.0°C
      • May be due to: prolonged exposure to cold environment, general anesthesia & surgery
    • Hyperthermia: > 38.5°C
      • May be due to: prolonged exposure to very hot environment, vigorous exercise, some drugs, brain injury
    • Fever:
      • Usually caused by an infection
      • Elderly: ≥ 37.2°C (persistent oral or tympanic) or ≥ 37.5°C (persistent rectal)

RESPIRATION

Respiration

  • Respiration provides the body’s cells with oxygen and removes carbon dioxide.
  • Involves:
    • Movement of air into (inspiration) and out of the lungs (expiration).
    • Gas exchange in the lungs.
    • Gas transport in the blood.
    • Gas exchange at the tissues.

A Respiratory Cycle

Maintaining Homeostasis of Blood Respiratory Gases with Breathing

Homeostatic Control of Breathing

  • Receptors: Chemoreceptors in certain arteries and medulla oblongata detect increased CO_2 (and H^+ ions).
  • Control Center: Respiratory center in the medulla oblongata is activated.
  • Effectors & Response: Increased rate and depth of breathing eliminates more CO_2. Diaphragm and external intercostal muscles are used, along with accessory muscles when needed.
  • Homeostatic Range: As carbon dioxide levels return to normal, feedback decreases effector responses.

Assessing Respirations – What are We Looking For?

  • Rate (breaths per minute).
  • Depth (observing chest or abdomen movement).
  • Rhythm.
  • Character of respirations (sound and effort).

Factors Affecting Respirations

  • Age
  • Exercise
  • Stress including pain, anxiety, fever
  • Environmental conditions including altitude
  • Medications

Interpreting Respiratory Rates

  • Normal ranges across the lifespan.

Interpreting Respiratory Rates

  • Abnormal findings:
    • Tachypnea: RR faster than the upper limit for age; Adult: > 20 breaths/minute
    • Bradypnea: RR slower than the lower limit for age; Adult: < 12 breaths/minute
    • Apnea: Absence of spontaneous breathing for 10 or more seconds

PULSE

Assessing the Pulse – What are We Looking For?

  • Pulse rate.
  • Pulse rhythm (pattern of pulses and intervals).
  • Pulse volume (size and duration of distension).

Factors That Affect Pulse Rate

Factors Affecting Body Pulse Rate

  • Age
  • Gender
  • Physical activity
  • Emotional status
  • Pain
  • Environmental factors
  • Stimulants
  • Medications
  • Disease state

Interpreting Pulse Rates

  • Normal ranges across the lifespan:
    • Newborn: 100-170 (Average 140)
    • 1 year: 80-160 (Average 120)
    • 3 years: 80-120 (Average 110)
    • 6 years: 70-115 (Average 100)
    • 10 years: 70-110 (Average 90)
    • 14 years: 60-110 (Average 85-90)
    • Adult: 60-100 (Average 72)

Interpreting Pulse Rates

  • Abnormal findings:
    • Tachycardia: Pulse rate faster than the upper limit for age; Adult: >100 beats/minute
    • Bradycardia: Pulse rate slower than the lower limit for age; Adult: <60 beats/minute.
    • Asystole: Absence of a pulse

BLOOD PRESSURE

Blood Pressure

  • Blood pressure in arteries fluctuates with the beating of the heart
  • Systolic pressure: Maximum pressure in the arteries when the heart contracts (systole)
  • Diastolic pressure: Minimum pressure in the arteries when the heart is relaxed between beats (diastole)

Factors That Determine Blood Pressure

  • Effectiveness of the heart as a pump
  • Ease with which blood flows through vessels
  • Volume of circulating blood

Maintaining Blood Pressure Homeostasis

Blood Pressure Regulation: When BP Rises

  • Receptors: Baroreceptors in certain arteries above the heart detect increased stretch (due to increased blood pressure).
  • Control Center: Cardiovascular center in the medulla oblongata receives & processes information from the baroreceptors.
  • Effectors & Response: Heart rate decreases, blood vessels widen.
  • Homeostatic Range: As blood pressure returns to normal, feedback decreases effector responses.

Imagine…

  • Challenge to describe the sequence of events that restores blood pressure to the normal range after a drop.

Blood Pressure Regulation: When BP Falls

Auscultating a Manual Blood Pressure

  • Sphygmomanometry: Arterial blood pressure is measured with a sphygmomanometer and a stethoscope.

Check Your Understanding

  • Assume a person has a BP of 124/72 mmHg
    • Systolic pressure: 124 mmHg
    • Diastolic pressure: 72 mmHg
    • Sound at 130mmHg: No sound
    • Sound at 110mmHg: Sound
    • Sound at 70mmHg: No sound

Interpreting Blood Pressure

  • NORMAL ranges across the lifespan:

Interpreting Blood Pressure

  • Abnormal findings in an adult:

Summary of Some Key Points

  • Vital signs indicate functioning of cardiovascular, respiratory, nervous, and endocrine systems.
  • Negative feedback mechanisms maintain homeostasis of core body temperature, respiratory gases and arterial blood pressure.
  • Awareness of factors affecting vital signs helps accurately interpret deviations from the normal range for a person’s age.

References

Additional References Used in Preparing This Material