Respiration, Blood Pressure, and Oxygen Saturation: Technique and Abnormal Recognition

Respiration, Blood Pressure, and Oxygen Saturation: Technique and Abnormal Recognition

Measuring and reporting vital signs accurately is one of the most important skills you will practice as a nursing assistant. The three signs covered in this lesson—respiratory rate, blood pressure, and oxygen saturation—together tell the care team whether a patient's heart, lungs, and circulation are working within safe ranges. An error in measurement or a missed abnormal value can delay treatment and harm the patient. Accuracy is not optional.

Measuring Respiratory Rate

Respiration is the rise and fall of the chest with each breath. One respiration equals one inhale plus one exhale. The normal adult rate is 12–20 breaths per minute at rest.

Why covert counting matters. Breathing is partly under conscious control. If a patient knows you are watching their breathing, they may unconsciously breathe faster or slower and give you a false number. The standard technique is to keep your fingers on the patient's wrist as though you are still counting the pulse, then shift your eyes to the chest and count silently for a full 60 seconds. Never count for 30 seconds and double; irregular breathing will not be detected that way.

What to observe. Note the rate (breaths per minute), depth (shallow, normal, or deep), and rhythm (regular or irregular). Noisy breathing, labored effort, or the use of neck and shoulder muscles to breathe are additional findings to report.

Abnormal respiratory rates:

• Tachypnea: rate above 20 breaths per minute
• Bradypnea: rate below 12 breaths per minute
• Apnea: complete absence of breathing—report immediately

Measuring Blood Pressure

Blood pressure (BP) is the force of blood against artery walls. It is recorded as two numbers: systolic (the pressure when the heart contracts) over diastolic (the pressure when the heart relaxes), written as mmHg. A typical normal adult range is roughly 90–119 mmHg systolic and 60–79 mmHg diastolic, though normal varies by the individual patient and their baseline.

Selecting and Applying the Cuff

Cuff size matters. A cuff that is too small will read falsely high; a cuff that is too large will read falsely low. The inflatable bladder inside the cuff should encircle at least 80 percent of the upper arm. Most clinical settings stock adult and large-adult cuffs—choose the correct one. Center the bladder over the brachial artery, align the cuff's artery marker with that landmark, and position the lower edge of the cuff about one inch (2–3 cm) above the antecubital crease. The patient's arm should rest at heart level, palm up.

Manual Auscultation Technique

1. Locate the brachial pulse with your fingertips.

2. Place the stethoscope diaphragm (or bell) lightly over the brachial artery—do not tuck it under the cuff.

3. Inflate the cuff to about 30 mmHg above the point where the radial pulse disappears, then release air at roughly 2–3 mmHg per second.

4. The first clear tapping sound you hear is the systolic reading. Note the gauge number.

5. The point at which sounds completely disappear is the diastolic reading.

6. Record to the nearest even number.

Automated Cuff

Automated devices apply the cuff the same way. Keep the arm still and at heart level during the reading; movement and talking cause errors. Cross-check automated readings against manual readings whenever results seem unexpected.

Factors That Affect Accuracy

• Talking, crossing legs, or a full bladder can raise systolic reading
• A recently used arm (IV site, dialysis shunt, mastectomy side) must not be used
• White-coat anxiety may elevate readings; allow the patient to rest for at least five minutes when possible
• Record which arm was used and the patient's position

Oxygen Saturation (SpO2)

A pulse oximeter uses light to estimate the percentage of hemoglobin in the blood that is carrying oxygen. Normal SpO2 in a healthy adult is 95–100%. Values below 95% require prompt reporting; values at or below 90% are generally considered a clinical emergency, though your facility's policy and the patient's baseline guide specific thresholds.

Applying the Oximeter

Clip-style sensors fit on a fingertip, usually the index or middle finger. The finger must be warm, dry, and free of dark nail polish or acrylic nails. Wait until the waveform on the device stabilizes before reading the number.

Causes of False or Inaccurate Readings

| Factor | Effect on reading |

|---|---|

| Dark nail polish or acrylic nails | May read falsely low |

| Cold or poorly perfused extremities | Weak signal; reading may be unreliable |

| Patient movement or shivering | Artifact; unstable waveform |

| Severe anemia | Device may read normal despite low oxygen-carrying capacity |

| Carbon monoxide exposure | Device cannot distinguish; may read falsely normal |

If the reading seems inconsistent with the patient's appearance (color, breathing effort), report your clinical observation to the nurse and note the factor you suspect.

Reporting with SBAR

When you find an abnormal value, report it to the nurse promptly using the SBAR format:

• Situation: what you observed right now
• Background: relevant patient context
• Assessment: what seems abnormal
• Recommendation: what you are requesting (a nurse to come assess the patient)

Example: *"The patient in room 4 has an SpO2 of 88% on room air. She is a 72-year-old with COPD. Her oxygen level is lower than her usual baseline of 93%. I need you to come assess her."

Safety Points

• Never take blood pressure on an arm with an IV line, a dialysis access site, or on the side of a mastectomy without a specific nurse order.
• Always report respiratory rates below 12 or above 20, BP readings significantly outside the patient's established baseline, and SpO2 below 95% (or per facility policy) without delay.
• Document exactly what the device displayed or what you counted—never round or estimate.
• Scope of practice: you measure and report; you do not diagnose or independently decide treatment.