Nursing Fundamentals: Vital Signs

Vital Signs Overview

  • Definition: Vital signs are critical indicators of a person's physiological state, typically including pulse, blood pressure, respiratory rate, temperature, oxygen saturation, and level of consciousness.
  • Purpose: These measurements help assess the general health and detect any changes in a patient’s condition.

Components of Vital Signs

Historical Context

  • Traditional Vital Signs: Pulse, blood pressure, respiratory rate, and temperature have been routinely used for over a century.
  • Recent Additions: Oxygen saturation and pain assessment have also been recognized as vital signs.
  • Level of Consciousness (LOC): Newly included as a critical sign for patient health, emphasizing comprehensive assessment.

Physiological Principles of Oxygen Delivery

  • Oxygen Delivery Equation:
  • Formula: Oxygen Delivery (mL/min) = Cardiac Output (L/min) × ([Hb] g/dL × SaO2 × 1.39 + 0.003 × PaO2)
  • Components:
    • Cardiac Output: Volume of blood pumped per minute, dependent on heart rate and stroke volume.
    • Hemoglobin Concentration ([Hb]): Reflects oxygen-carrying capacity.
    • Arterial Oxygen Saturation (SaO2): Percentage of hemoglobin saturation.
    • Partial Pressure of Oxygen (PaO2): Measures dissolved oxygen in blood.

Specific Vital Signs

Pulse

  • Definition: Represents the number of heartbeats per minute and characteristics of blood flow.
  • Assessment: Check for rate (number of beats), rhythm (regularity), and volume (strength of pulse).
  • Normal Ranges: 60-100 beats per minute for adults.

Blood Pressure

  • Definition: The force exerted by circulating blood on the walls of blood vessels.
  • Measurement: Systolic (pressure during heart contractions) and diastolic (pressure when the heart is at rest).
  • Factors Affecting Blood Pressure:
  • Cardiac output, blood volume, peripheral resistance.
  • Normal values: Systolic <120 mmHg and Diastolic <80 mmHg.

Respiratory Rate

  • Definition: The number of breaths taken in one minute.
  • Normal Ranges: 12-20 breaths per minute; tachypnoea (>20), bradypnoea (<12).
  • Indicators of Deterioration: Changes in respiratory rate can signify health issues.

Oxygen Saturation (SaO2)

  • Measurement: % of hemoglobin saturated with oxygen, typically assessed using pulse oximetry.
  • Normal Values: 95-100% is ideal, with <90% indicating potential hypoxemia.

Temperature

  • Normal Range: Core temperature averages around 37°C, with variations depending on the measurement site (oral, axillary, rectal).
  • Fever: A body temperature above 37.4°C; indicative of infection or inflammation.

Level of Consciousness (LOC)

  • Assessment Tools: AVPU scale (Alert, Voice, Pain, Unresponsive) for quick evaluations, with detailed tools like the Glasgow Coma Scale (GCS) used for comprehensive assessments.

Importance of Vital Signs in Nursing

  • Monitoring: Routine monitoring helps in early detection of patient deterioration.
  • Documentation: Accurate recording on observation charts for tracking trends and initiating proper medical intervention.
  • Critical Decision-Making: Continuous assessment allows for timely escalation of care and intervention in emergencies.

Escalation Protocols

  • Actions Based on Scores: Use observation and response charts, such as ADDS to determine the need for further medical review based on vital signs scores.
  • Intervention Examples: Increasing observation frequency, alerting senior medical staff, and implementing emergency actions when critical thresholds are met.