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❤️‍🩹First Aid

Vital Signs

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Why This Matters

Vital signs are your window into what's happening inside a person's body when you can't see the problem directly. In first aid situations, these five measurements—pulse rate, respiratory rate, blood pressure, body temperature, and level of consciousness—tell you whether someone is stable, deteriorating, or in immediate danger. You're being tested on your ability to recognize normal ranges, abnormal findings, and what those changes indicate about underlying conditions like shock, respiratory failure, or neurological emergencies.

Don't just memorize the numbers—understand what each vital sign reveals about body function and how changes guide your response. A rapid pulse and fast breathing together might suggest shock; an unresponsive patient with slow breathing demands immediate airway management. The real skill is connecting the dots between vital signs and appropriate interventions, which is exactly what exam questions will ask you to do.


Cardiovascular Indicators

These vital signs reflect how well the heart and blood vessels are delivering oxygen throughout the body. When circulation fails, these measurements change first—often before visible symptoms appear.

Pulse Rate

  • Normal adult range is 60–100 beats per minute—measured at the radial (wrist) or carotid (neck) artery for quick assessment
  • Rapid, weak, or thready pulse suggests shock, dehydration, or blood loss requiring immediate intervention
  • Quality matters as much as rate—note whether the pulse is strong or weak, regular or irregular

Blood Pressure

  • Normal reading is approximately 120/80 mmHg—the top number (systolic) measures pressure during heartbeats, the bottom (diastolic) between beats
  • Hypotension (low BP) in emergencies often indicates shock or severe blood loss and requires positioning and rapid transport
  • Cannot be measured without equipment—in field situations, assess pulse quality and skin signs as indirect indicators

Compare: Pulse rate vs. blood pressure—both reflect cardiovascular function, but pulse can be assessed immediately without equipment while blood pressure requires a sphygmomanometer. If you can only check one vital sign quickly, pulse gives you the fastest insight into circulation status.


Respiratory Indicators

Breathing rate and quality reveal whether the body is getting adequate oxygen. The respiratory system compensates for many problems—increased breathing often signals the body is working harder to maintain oxygen levels.

Respiratory Rate

  • Normal adult range is 12–20 breaths per minute—count for 30 seconds and multiply by two for accuracy
  • Tachypnea (rapid breathing) may indicate respiratory distress, pain, anxiety, or metabolic problems like diabetic ketoacidosis
  • Bradypnea (slow breathing) is more dangerous—suggests respiratory failure, drug overdose, or brain injury requiring immediate airway support

Compare: Tachypnea vs. bradypnea—rapid breathing means the body is compensating and still fighting; slow breathing often means the system is failing. Bradypnea in an unresponsive patient is a critical emergency requiring immediate intervention.


Temperature Regulation

Body temperature reflects the balance between heat production and heat loss. Extreme temperatures in either direction can be life-threatening and require opposite interventions.

Body Temperature

  • Normal range is 97°F–99°F (36.1°C–37.2°C)—slight variations depend on measurement site and time of day
  • Fever (hyperthermia) above 100.4°F indicates infection or heat illness; treat the underlying cause and cool if dangerously elevated
  • Hypothermia below 95°F (35°C) is a medical emergency—handle gently, remove wet clothing, and warm gradually to prevent cardiac complications

Compare: Hyperthermia vs. hypothermia—both are temperature emergencies, but treatment is opposite. Cooling an overheated patient and warming a hypothermic patient seem obvious, but rapid temperature changes in either direction can cause dangerous complications. Gradual correction is key.


Neurological Indicators

Level of consciousness tells you how well the brain is functioning. Changes in awareness are often the earliest warning sign of serious conditions affecting the brain's oxygen or blood supply.

Level of Consciousness

  • AVPU scale provides rapid assessment—Alert, responds to Verbal stimuli, responds to Pain, or Unresponsive
  • Any decline from baseline suggests serious conditions including head injury, stroke, hypoglycemia, overdose, or shock
  • Unresponsive patients require immediate airway management—the tongue can obstruct breathing, so positioning and airway protection become priority one

Compare: Alert vs. unresponsive patients—an alert patient can protect their own airway and tell you what's wrong; an unresponsive patient cannot. This single vital sign determines whether you focus on gathering information or managing life-threatening airway compromise.


Quick Reference Table

ConceptBest Examples
Cardiovascular functionPulse rate, blood pressure
Respiratory functionRespiratory rate, breathing quality
ThermoregulationBody temperature (fever, hypothermia)
Neurological functionLevel of consciousness (AVPU)
Shock indicatorsRapid/weak pulse, low BP, altered consciousness
Can assess without equipmentPulse, respiratory rate, LOC, skin temperature
Requires equipment for accuracyBlood pressure, core body temperature
Airway emergency triggersUnresponsive LOC, bradypnea

Self-Check Questions

  1. A patient has a rapid, weak pulse and fast, shallow breathing. Which two vital sign changes together most strongly suggest shock, and what underlying problem do they indicate?

  2. Compare and contrast tachypnea and bradypnea—which is more immediately dangerous in an unresponsive patient, and why does this guide your intervention priority?

  3. Using the AVPU scale, what is the critical difference between a patient who responds to verbal stimuli versus one who responds only to pain? How does this change your assessment approach?

  4. A hiker is found with slurred speech, confusion, and skin that feels cold. Which vital signs would you prioritize checking, and what condition do these findings suggest?

  5. If you had no equipment available, which three vital signs could you still assess, and what information would each provide about the patient's condition?