Vital Signs

Role of Vital Signs in Patient Assessment

Vital signs are objective measurements of the body’s basic physiological functions. They include temperature, pulse, respiration, and blood pressure—often referred to as TPR and BP. For the Certified Nursing Assistant (CNA), measuring and reporting vital signs accurately is a core clinical skill. Vital signs provide early warning of changes in a patient’s condition, guide treatment decisions, and are a standard component of every patient assessment. On the CNA exam, you will be tested on the correct techniques, normal ranges, infection control practices, and when to report abnormal findings to the nurse.^[1]

Standard Vital Sign Terminology and Ranges

• Vital Signs: Measurements of the body’s basic functions—temperature, pulse, respiration, and blood pressure. Pain is sometimes considered the fifth vital sign.
• Temperature: The balance between heat produced and heat lost by the body. Measured in degrees Fahrenheit (°F) or Celsius (°C).
• Pulse: The rhythmic expansion of an artery caused by the ejection of blood from the left ventricle. Measured in beats per minute (bpm).
• Respiration: The act of breathing (inhalation and exhalation). Measured in breaths per minute (bpm).
• Blood Pressure: The force of blood against the walls of the arteries. Recorded as systolic/diastolic (e.g., 120/80 mmHg).
• Hypothermia: Body temperature below 95°F (35°C).
• Hyperthermia: Body temperature above 99°F (37.2°C) oral; fever is a form of hyperthermia often due to infection.
• Tachycardia: Resting heart rate above 100 bpm.
• Bradycardia: Resting heart rate below 60 bpm.
• Tachypnea: Respiratory rate above 20 breaths per minute.
• Bradypnea: Respiratory rate below 12 breaths per minute.
• Hypertension: Blood pressure consistently above 130/80 mmHg.
• Hypotension: Blood pressure below 90/60 mmHg.

Step-by-Step Vital Sign Measurement Techniques

Temperature

Temperature can be measured by several routes. Each route has a normal range and specific equipment. The CNA must use the correct technique to ensure accuracy and patient safety.^[2]

• Oral: Under the tongue in the sublingual pocket. Wait 15–30 minutes after the patient has eaten, drunk, or smoked. Normal: 97.6–99.6°F (36.5–37.5°C).
• Rectal: The most accurate core temperature. Insert thermometer 1–1.5 inches in adults. Lubricate tip. Normal: 98.6–100.6°F (37–38.1°C).
• Axillary: Under the arm in the skin fold. Least accurate. Normal: 94.5–98.6°F (34.7–36.5°C).
• Tympanic: Ear canal. Fast and noninvasive. Pull ear pinna back and up (adult). Normal: 98.6°F (37°C).
• Temporal: Forehead using infrared scanner. Sweep across forehead, then behind ear. Normal: 99.1–100.6°F (37.3–38°C).

Steps for Oral Temperature (Digital Thermometer)

1. Perform hand hygiene and gather supplies (thermometer, probe cover, gloves).
2. Identify the patient and explain the procedure.
3. Put on clean gloves.
4. Place a probe cover over the thermometer.
5. Insert the thermometer tip into the sublingual pocket at the base of the tongue.
6. Hold in place until the thermometer beeps (approximately 10–20 seconds).
7. Remove, read the display, and discard the probe cover without touching the used cover.
8. Document the result and report any abnormal value to the nurse.

Pulse

The pulse reflects the heart rate and rhythm. The most common site for routine vital signs is the radial pulse (at the wrist). The apical pulse is heard with a stethoscope over the heart’s apex and is used for infants, irregular rhythms, or when peripheral pulses are weak.^[3]

• Normal adult pulse range: 60–100 bpm.
• Factors that can increase pulse: exercise, fever, anxiety, pain, medications, blood loss.
• Factors that can decrease pulse: sleep, athletes, certain heart medications (beta-blockers).

Steps for Measuring Radial Pulse

1. Patient’s arm should be relaxed and supported (resting on a table or armrest).
2. Place the pads of your first two or three fingers over the radial artery (thumb side of the wrist).
3. Apply gentle pressure until you feel the pulse.
4. Count for 30 seconds and multiply by 2, or count for a full 60 seconds if irregular.
5. Note the rhythm (regular or irregular) and strength (bounding, weak, thready).
6. Document the rate, rhythm, and strength.

Respiration

Respiration is often measured immediately after taking the pulse without the patient knowing, because conscious control can alter the rate. One respiration = one inhalation + one exhalation.^[1]

• Normal adult range: 12–20 breaths per minute.
• Depth: deep, shallow, normal.
• Rhythm: regular or irregular.

Steps for Measuring Respiration

1. Keep your hand on the patient’s wrist as if still taking the pulse.
2. Observe the rise and fall of the chest or abdomen.
3. Count breaths for 30 seconds and multiply by 2.
4. Note any difficulty, audible sounds (wheezing, stridor), or accessory muscle use.
5. Document the rate, depth, and rhythm.

Blood Pressure

Blood pressure is measured using a sphygmomanometer (cuff and manometer) and a stethoscope. The first sound heard (Korotkoff phase I) is systolic; the point at which sounds disappear (phase V) is diastolic.^[4]

• Normal adult blood pressure: less than 120/80 mmHg.
• Elevated: 120–129 systolic and less than 80 diastolic.
• Hypertension stage 1: 130–139 systolic or 80–89 diastolic.
• Hypertension stage 2: 140 or higher systolic or 90 or higher diastolic.
• Hypotension: below 90/60 mmHg.

Steps for Measuring Blood Pressure (Manual)

1. Patient should be seated with feet flat, back supported, and arm at heart level (rest on table).
2. Select appropriate cuff size (bladder should encircle 80% of the arm).
3. Place the cuff 1 inch above the antecubital space, centered over the brachial artery.
4. Palpate the brachial pulse and inflate cuff 30 mmHg above the point where pulse disappears.
5. Place the stethoscope over the brachial artery (not under the cuff).
6. Release valve slowly (2–3 mmHg per second).
7. Note the first tapping sound (systolic) and the last sound (diastolic).
8. Deflate completely, remove cuff, and document readings.

Recognizing and Reporting Abnormal Vital Signs

The CNA must recognize abnormal vital signs and report them promptly. Common abnormal findings include:

• Fever: Flushed skin, diaphoresis, chills, increased pulse and respiration.
• Hypothermia: Pale, cool skin; shivering; drowsiness; low pulse and respirations.
• Weak or thready pulse: May indicate low blood volume or shock.
• Bounding pulse: May indicate hypertension or fever.
• Irregular pulse: Could indicate arrhythmia; always count for a full 60 seconds.
• Labored breathing: Use of accessory muscles, nasal flaring, retractions, cyanosis.
• Orthostatic hypotension: Drop in blood pressure when standing; report dizziness or syncope.

Documentation and Normal Ranges for Vital Signs

The CNA documents vital signs immediately after measurement. Use the patient’s medical record (paper or electronic). Include date, time, value, route (if temperature), and any relevant observations (e.g., “patient shivering,” “pulse irregular”).^[5] Abnormal values must be reported to the licensed nurse promptly. The CNA does not interpret or diagnose—only measure, record, and report.

Patient Comfort and Safety During Vital Signs

The CNA’s role regarding vital signs focuses on accurate measurement, patient comfort, and safety. Interventions may include:

• Repositioning the patient for comfort and accurate measurement.
• Providing a warm blanket for a patient with low temperature.
• Encouraging slow, deep breathing when patient is anxious (only if allowed by facility policy).
• Notifying the nurse immediately of abnormal findings, especially if patient shows signs of distress.
• Ensuring the patient is calm and has not exercised, smoked, or consumed caffeine within the last 30 minutes (for accurate resting vitals).

Infection Control and Safety Protocols for Vitals

• Infection control: Use disposable probe covers for thermometers; clean reusable equipment after each use. Wear gloves when there is potential exposure to blood or body fluids.^[6]
• Cross-infection: Never use a thermometer without a cover or without cleaning per facility policy.
• Blood pressure cuff: Do not place on an arm with an IV line, recent trauma, dialysis fistula, or mastectomy (on the same side).
• Rectal temperature: Use caution in patients who have had rectal surgery, are neutropenic, or have a heart condition—insertion can cause vagal stimulation.
• Pressure injury: Do not leave the blood pressure cuff inflated too long; can cause arm pain or nerve damage.
• Patient falls: Assist weak or dizzy patients when changing positions for vital sign measurement.

CNA Exam Preparation for Vital Signs

• Normal ranges: Memorize adult ranges—temperature 97.6–99.6°F oral, pulse 60–100, respirations 12–20, BP <120/80.
• Route differences: Rectal is highest (0.5–1°F higher than oral); axillary is lowest (0.5–1°F lower).
• Counting irregular pulse: Always count for full 60 seconds.
• Counting respirations: Do it after taking pulse without letting the patient know you are counting.
• Equipment: Know how to read a mercury or aneroid manometer (calibration line at zero).
• Common exam questions:
  • “What should the CNA do first if a patient’s blood pressure is 180/100?” – Report to the nurse immediately (do not recheck without instruction).
  • “Which site is most accurate for core temperature?” – Rectal.
  • “When should you use an apical pulse?” – Infants, irregular heartbeats, or to verify a weak peripheral pulse.
• Memory aid: “TPR and BP” – Temperature, Pulse, Respiration, Blood Pressure. Always document in that order.
• Clean gloves: Required for any procedure that might involve contact with mucous membranes, blood, or body fluids (e.g., oral temperature if using glass thermometer, rectal temperature).

References & Sources

1. Potter, P. A., & Perry, A. G. (2017). Fundamentals of Nursing (9th ed.). Elsevier. https://shop.elsevier.com/books/fundamentals-of-nursing/potter/978-0-323-32740-4
2. National Council of State Boards of Nursing (NCSBN). (2023). NCLEX-PN&RN Test Plans. https://www.ncsbn.org/exams/next-generation-nclex.page
3. American Heart Association. (2020). Guidelines for CPR and ECC. https://cpr.heart.org/en/resuscitation-science/cpr-and-ecc-guidelines
4. Centers for Disease Control and Prevention. (2023). High Blood Pressure. https://www.cdc.gov/bloodpressure/index.htm
5. Wilson, S. F., & Giddens, J. F. (2020). Health Assessment for Nursing Practice (6th ed.). Elsevier. https://www.amazon.com/Health-Assessment-Nursing-Practice-Wilson/dp/0323377769
6. Centers for Disease Control and Prevention. (2023). Standard Precautions for All Patient Care. https://www.cdc.gov/infection-control/hcp/basics/standard-precautions.html