Vital Signs and Their Assessment

Vital Signs

• Vital signs include temperature, pulse, respiration, and blood pressure.
• Pain is sometimes considered a fifth vital sign.
• Changes in vital signs can indicate changes in health.

Frequency of Vital Sign Assessments

• Stable patients typically have vital signs checked every 4 hours.
• Unstable patients, those taking medications affecting cardiovascular or respiratory function, or those who've had surgery, require more frequent vital sign checks.

Assessing Body Temperature

• Body temperature is the heat of the body, measured in degrees.
• Regulated by the thermoregulatory center in the hypothalamus, which receives signals from thermal receptors in the skin.
• These receptors either produce or conserve body heat, keeping temperature within a 36.4°C–37.3°C range.
• Heat is lost when body heat is transferred to the skin surface via circulating blood.
• Deep body temperature remains fairly constant, but surface temperatures vary with environmental factors.
• Body temperature balance maintains homeostasis.
• Fluctuations in temperature affect fluid balance.

Types of Thermometers

• Electronic thermometers: Measure temperature in 25–50 seconds. Suitable for oral, rectal, and axillary sites. They often have disposable covers to minimize cross-contamination.
• Tympanic thermometers: Use infrared sensors to measure temperature from the eardrum in under 2 seconds. Disposable covers are often used.
• Glass thermometers: Contain mercury, which expands with heat and contracts with cold.
• Temperature-sensitive patch/tape: Applied to forehead or abdomen, color changes indicate temperature. A thermometer is needed to confirm.
• Automated monitoring devices: Used in healthcare settings to measure temperature, pulse, and blood pressure.

Factors Affecting Body Temperature

• Circadian rhythms: Body temperature is typically 0.6°C lower in the early morning than late afternoon.
• Age: Very young and very old are more sensitive to environmental temperature changes.
• Gender: Women tend to have more fluctuations in temperature due to hormonal changes, such as a rise in progesterone around ovulation.
• Stress: Stress increases epinephrine and norepinephrine production, increasing metabolic rate and temperature.
• Environmental temperature: Body responds to environmental temperature changes by adjusting clothing to control heat loss or retention.

Terms & Definitions for Types of Fever

• Intermittent: Temperature alternates regularly between fever, normal, or subnormal.
• Constant: Temperature stays elevated with minimal fluctuations (less than 2°C).
• Relapsing: Temperature returns to normal for at least a day before recurring.
• Crisis: Temperature returns to normal suddenly.
• Lysis: Temperature returns to normal gradually.

Areas to Measure Temperature From

Oral Temperature

• Patient must be able to close their mouth.
• Placed under the tongue and left for 3 minutes.
• Contraindications include unconsciousness, seizures, infants/young people with oral cavity diseases, and recent consumption of hot/cold food/fluids or smoking. Wait 15-30 minutes after consumption.

Rectal Temperature

• Most accurate method, as it measures internal temperature.
• Lubricate the thermometer.
• Insert and leave for 1 minute.
• Contraindications include rectal surgery, diarrhea, rectal diseases, and cardiac surgery (as the thermometer may slow the heart rate).

Axillary Temperature

• Used when oral and rectal temperature measurements are contraindicated.
• Some hospitals use it with newborns to prevent rectal wall perforation.

Average Normal Temperatures for Healthy Adults

• Oral: 37°C
• Rectal: 37.5°C
• Axillary: 36.5°C

Assessing Respirations

• Respiration: Movement of air into and out of the lungs.
• Inspiration: Inhalation (breathing in).
• Expiration: Exhalation (breathing out).
• External respiration: Exchange of O2 and CO2 between alveoli and circulating blood.
• Internal respiration: Exchange of O2 and CO2 between circulating blood and cells in tissues.

Factors Affecting Respiration

• Exercise, respiratory/cardiovascular disease, medications, trauma, infection, pain, and anxiety impact respiration.
• Eupnea: Normal breathing rate, typically 16–20 breaths per minute. Consistent relationship to heart rate (one breath equals roughly four heart beats).
• Tachypnea: Rapid breathing, often due to elevated body temperature (pyrexia) or increased metabolic demands. A temperature rise of every 0.6°C correlates to roughly 4 more breaths per minute.
• Bradypnea: Slow breathing due to depression in the respiratory center or certain medications (e.g., morphine).
• Respiratory depth: Varies from shallow to deep.
  • Apnea: Absence of breathing. Apnea lasting longer than 4-6 minutes can lead to serious brain damage or death.
  • Dyspnea: Difficulty breathing, often rapid and shallow.
  • Orthopnea: Difficulty breathing when lying flat, but breathing is easier when upright.