Accurate measurement of vital signs is the foundation of nursing assessment. Normal adult oral temperature ranges from 36.1°C to 37.2°C (97.0°F to 99.0°F), with values above 38.0°C (100.4°F) defining fever and below 35.0°C (95.0°F) defining hypothermia. Resting respiratory rate is 12 to 20 breaths per minute; the nurse should count for a full minute without alerting the patient, because awareness causes conscious alteration of breathing. A resting heart rate of 60 to 100 beats per minute is normal, with bradycardia below 60 and tachycardia above 100. When the rhythm is irregular, the pulse should be counted for 60 seconds to detect dysrhythmias. Normal blood pressure is systolic below 120 mmHg and diastolic below 80 mmHg, while mean arterial pressure (MAP) of 70 to 100 mmHg reflects organ perfusion and is calculated as (SBP + 2 × DBP) ÷ 3.
The order of vital sign assessment is intentionally designed to avoid influencing the patient. Respirations are counted first, typically while still holding the wrist after palpating the pulse, followed by blood pressure, temperature, and pain. Pulse oximetry measures the percentage of hemoglobin saturated with oxygen (SpO₂), with normal values of 95–100%; however, it does not assess ventilation, so carbon dioxide retention can still occur even with normal saturation. Pulse oximetry is unreliable in carbon monoxide poisoning because carboxyhemoglobin absorbs light similarly to oxyhemoglobin, producing falsely elevated readings. The apical pulse, auscultated at the fifth intercostal space midclavicular line, is preferred for infants, patients with irregular rhythms, and those receiving cardiac medications.
Physical assessment follows a structured sequence of inspection, palpation, percussion, and auscultation, except in the abdomen where auscultation precedes percussion and palpation to avoid altering bowel sounds. Subjective data refers to what the patient reports, while objective data are measurable signs observed by the nurse. Focused assessments include the chief complaint, history of present illness, targeted review of systems, and pertinent physical examination using the four techniques. Pain is evaluated using the PQRST mnemonic: Provocation/Palliation, Quality, Region/Radiation, Severity (0–10), and Timing. For cognitively impaired adults who cannot self-report, observational tools such as PAINAD or FLACC assess breathing, vocalization, facial expression, body language, and consolability.
Abnormal respiratory patterns provide diagnostic clues. Cheyne-Stokes respirations feature crescendo-decrescendo breathing alternating with apnea, suggesting heart failure, stroke, or increased intracranial pressure. Kussmaul respirations are deep, rapid, and labored, classically compensating for metabolic acidosis in diabetic ketoacidosis. Biot respirations consist of irregular quick, shallow gasps with unpredictable apnea, indicating brainstem injury or impending respiratory arrest. Recognizing these patterns allows the nurse to escalate care rapidly. Tools such as the Braden Scale predict pressure injury risk across six subscales, while the Morse Fall Scale identifies fall hazards with a score of 45 or greater signaling high risk requiring targeted interventions.