Vital Signs

Overview

Vital signs are the fundamental measurements that healthcare providers use to assess a patient's physiological status. The five primary vital signs are body temperature, pulse rate, respiratory rate, blood pressure, and oxygen saturation (SpO2). These measurements provide a baseline for patient assessment and help identify life-threatening conditions early.

Accurate vital sign measurement requires proper technique, calibrated equipment, and an understanding of normal ranges across different age groups. Trending vital signs over time is often more valuable than any single reading, as it reveals whether a patient is improving, stable, or deteriorating.

Normal Adult Ranges

• Temperature: 97.8–99.1°F (36.5–37.3°C) oral
• Pulse: 60–100 beats per minute at rest
• Respirations: 12–20 breaths per minute
• Blood pressure: systolic 90–120 mmHg, diastolic 60–80 mmHg
• SpO2: 95–100% on room air

Measurement Techniques

Temperature can be measured via oral, tympanic, temporal, axillary, or rectal routes. Rectal is the most accurate core temperature but is invasive. Each route has a known offset from core temperature that must be documented.

Pulse is assessed by palpating a peripheral artery—most commonly the radial artery at the wrist. Count beats for a full 60 seconds if the rhythm is irregular. Note rate, rhythm, and quality. An apical pulse is auscultated at the left midclavicular line, fifth intercostal space.

Blood pressure is measured using a sphygmomanometer and stethoscope or an automated oscillometric device. Proper cuff size—bladder width covering 40% of arm circumference—is essential. A cuff that is too small gives falsely high readings; one that is too large gives falsely low readings.

Clinical Significance

Abnormal vital signs trigger clinical decision-making. Tachycardia (pulse >100) may indicate pain, anxiety, fever, dehydration, or shock. Bradycardia (pulse <60) can result from medications, increased intracranial pressure, or cardiac conduction abnormalities. Hypotension (systolic <90 mmHg) is a hallmark of shock.

In the prehospital setting, EMTs and paramedics use serial vital signs to guide treatment decisions. A narrowing pulse pressure or rising heart rate in a trauma patient suggests internal hemorrhage. In long-term care, CNAs report any deviation from a resident's established baseline to the nurse immediately.

Documentation must include the time, method, position of the patient, and any relevant context. Vital signs are a cornerstone of communication during patient handoffs using frameworks like SBAR.