Vital signs are the fastest objective measure of how well the body is maintaining temperature, circulation, breathing, and perfusion. The four classic vital signs are temperature, pulse, respiration, and blood pressure (BP). Most facilities also record oxygen saturation (SpO₂) and pain with every set. Blood glucose is an important bedside test but is not a vital sign.

Why they change

• Temperature reflects the balance between heat production and heat loss, controlled by the hypothalamus.
• Pulse reflects heart rate and rhythm and, indirectly, stroke volume. Pulse rises with fever, pain, anxiety, exercise, hypovolemia, anemia, hypoxemia, and sympathomimetic drugs; it falls with beta-blockers, digoxin, athletic conditioning, increased vagal tone, and heart block.
• Respiration is controlled by the medulla and pons and is driven mainly by rising PaCO₂. Opioids and sedatives slow it; fever, pain, anxiety, hypoxemia, and metabolic acidosis speed it up.
• Blood pressure = cardiac output × systemic vascular resistance. Low BP with a rising heart rate is an early warning of shock.

Normal adult ranges (resting)

Age-specific ranges (awake; approximate, references vary — follow the facility chart)

Newborn axillary temperature is normally 36.5–37.5 °C (97.7–99.5 °F). Older adults often run lower baselines and may not mount a typical fever; in long-term care, suspect fever with a single oral temperature > 37.8 °C (100 °F), repeated oral readings > 37.2 °C (99 °F), or a rise of > 1.1 °C (2 °F) above baseline. Always compare with the client's own baseline.

Temperature by site

True core temperature is measured invasively (pulmonary artery, esophageal, or bladder probe) in critical care.

Pulse

• Use the radial pulse for routine adult checks; palpate with the pads of the index and middle fingers, never the thumb (it has its own pulse).
• Count for 30 seconds × 2 if regular; count a full minute if irregular, and take an apical pulse for 1 minute at the fifth intercostal space, midclavicular line, before giving digoxin or when the rhythm is irregular.
• Pulse deficit = apical rate − radial rate (measured simultaneously by two nurses); it indicates ineffective beats, as in atrial fibrillation.
• Grade strength: 0 absent, 1+ weak, 2+ normal, 3+ increased, 4+ bounding.
• Use the carotid pulse in emergencies (adults) and the brachial pulse in infants.

Respirations

• Count without the client knowing — keep fingers on the wrist after counting the pulse and watch the chest. Count 30 seconds × 2 if regular, a full minute if irregular.
• Assess rate, depth, rhythm, and effort (accessory muscle use, retractions, nasal flaring).

Order: a common routine is temperature, pulse, respirations, then BP, with respirations counted while the fingers are still on the pulse.

Blood pressure measurement technique (AHA-based)

1. Client rests quietly for at least 5 minutes, seated, back supported, feet flat, legs uncrossed; no talking. Avoid caffeine, exercise, and smoking for 30 minutes beforehand; empty bladder.
2. Bare arm, supported at heart level.
3. Correct cuff size: bladder length about 80% and width about 40% of the arm circumference. Measure the arm; do not guess — arm 22–26 cm small adult cuff; 27–34 cm adult; 35–44 cm large adult; 45–52 cm adult thigh cuff.
4. For auscultation, palpate the brachial artery and estimate systolic pressure by palpation, then inflate 20–30 mmHg above the point where the pulse disappears (this avoids missing an auscultatory gap).
5. Deflate at 2–3 mmHg per second.
6. Systolic = first clear tapping sound (Korotkoff phase I); diastolic = disappearance of sounds (phase V) in adults.
7. Take 2 or more readings 1–2 minutes apart and average them. At the first visit, measure both arms and use the higher arm thereafter.

Common errors

BP categories in adults — 2017 ACC/AHA, unchanged in the 2025 AHA/ACC guideline

• The term "prehypertension" is outdated; 120–129/< 80 is now called elevated BP. Older test banks that call 120–139/80–89 "prehypertension" follow the retired 2003 classification.
• Severe hypertension is systolic > 180 and/or diastolic > 120 mmHg without acute target-organ damage (replaces "hypertensive urgency"). With new or worsening target-organ damage (chest pain, neurologic deficit, pulmonary edema, acute kidney injury) it is a hypertensive emergency.
• Diagnosis is based on the average of readings on two or more occasions, and should be confirmed with out-of-office readings (home BP monitoring or 24-hour ambulatory monitoring).
• White coat hypertension: high in the clinic, normal outside. Masked hypertension: normal in the clinic, high at home. Both are detected by out-of-office monitoring.

Orthostatic (postural) vital signs: measure lying for 5 minutes, then standing at 1 and 3 minutes. A drop of ≥ 20 mmHg systolic or ≥ 10 mmHg diastolic within 3 minutes indicates orthostatic hypotension; a large heart rate rise suggests volume depletion.

Pulse oximetry: reliable only with a good waveform. Readings are falsely affected by poor perfusion, cold fingers, motion, dark nail polish, and carbon monoxide poisoning (falsely normal). Pulse oximeters can overestimate saturation in clients with darker skin pigmentation; FDA draft guidance (2025) calls for testing across skin tones. Until devices improve, treat borderline readings with caution and correlate with the clinical picture and ABGs.

Nurses measure and interpret vital signs; the provider orders treatment based on trends.

• Many hospitals use an early warning score (combining RR, SpO₂, BP, pulse, temperature, and level of consciousness) that triggers a rapid response team.
• Hypertension: the 2025 AHA/ACC guideline keeps a treatment goal of < 130/80 mmHg for most adults and uses the PREVENT risk calculator. Stage 2, or stage 1 with clinical cardiovascular disease, diabetes, chronic kidney disease, or 10-year PREVENT risk ≥ 7.5%, is treated with medication plus lifestyle change; lower-risk stage 1 starts with 3–6 months of lifestyle change. Stage 2 usually starts with two first-line drugs of different classes, preferably as a single-pill combination.
• Hypertensive emergency is treated in intensive care with IV agents; lower BP by no more than about 25% in the first hour, then toward 160/100–110 mmHg over the next 2–6 hours, then gradually to normal over 24–48 hours, to avoid cerebral and coronary ischemia. Faster lowering is reserved for specific conditions (ACC/AHA): in acute aortic dissection, systolic BP below 120 mmHg during the first hour (some summaries say within about 20 minutes); in severe preeclampsia or eclampsia and pheochromocytoma crisis, systolic BP below 140 mmHg during the first hour.
• Antipyretics (acetaminophen, NSAIDs) for fever causing discomfort, with a search for the cause.

Drug safety for common drugs that change vital signs

• Beta-blockers (e.g., metoprolol): bradycardia, hypotension, masked hypoglycemia, bronchospasm in asthma. Check apical pulse and BP first; hold per order if heart rate < 60/min or systolic BP below the ordered limit. Do not stop abruptly.
• Digoxin: take an apical pulse for 1 full minute; usually hold and notify if < 60/min in adults. Toxicity (nausea, vision changes, dysrhythmias) is more likely with hypokalemia.
• Opioids and sedatives: check respiratory rate and sedation level before and after doses; see Pain Management.

1. Recognize instability first. A single abnormal value is rechecked promptly; an abnormal value with symptoms (chest pain, confusion, dyspnea, cool clammy skin) or a worsening trend is reported immediately. Low BP, rising heart rate, and rising respiratory rate together suggest shock.
2. Use correct equipment and technique — correct cuff size, correct site, and a validated device. Verify an unexpected automatic reading manually.
3. Measure at the right times: on admission, per routine, before and after procedures and high-risk medications, with any change in condition, and after transfusion starts.
4. Know the client's baseline and compare; a BP of 100/60 mmHg can be normal for one client and shock for another.
5. Delegation: assistive personnel can measure vital signs on stable clients, but the nurse interprets abnormal values and assesses unstable clients.
6. Fever care: encourage fluids, light clothing, and antipyretics as ordered; avoid chills and do not cover with heavy blankets.
7. Document values, site, position, device, and actions taken.

• Home BP monitoring: use a validated upper-arm device with the correct cuff; sit quietly for 5 minutes; take 2 readings 1 minute apart in the morning before medications and in the evening; record all readings and bring the device to a clinic visit to check accuracy.
• Avoid caffeine, exercise, and smoking 30 minutes before measuring.
• Lifestyle measures that lower BP: weight loss, DASH-style diet, sodium reduction, potassium-rich foods (unless kidney disease or potassium-raising drugs), regular physical activity, limiting alcohol, and not smoking.
• Rise slowly from lying to standing if dizzy on standing.
• Teach clients taking digoxin or beta-blockers how to count their pulse and when to call.
• A fever of 38.0 °C (100.4 °F) or higher in a client receiving chemotherapy, or any fever with a stiff neck, confusion, or difficulty breathing, needs prompt medical attention.

Act immediately for new confusion, SpO₂ that will not rise, or falling BP — call the rapid response team per policy.

• Count respirations without the client's awareness, fingers still on the pulse
• Adult normals: pulse 60–100, respirations 12–20, BP < 120/80
• Rectal is the most accurate noninvasive temperature site; axillary is the least accurate
• Apical pulse for 1 full minute before digoxin and for irregular rhythms; pulse deficit = apical − radial
• Cuff too small → falsely high; cuff too large → falsely low; bladder width about 40% of arm circumference
• Deflate at 2–3 mmHg/second; slow deflation raises the diastolic reading
• Palpate first and inflate 20–30 mmHg above the obliteration point to avoid the auscultatory gap
• Elevated BP = 120–129/< 80; stage 1 = 130–139 or 80–89; stage 2 ≥ 140 or ≥ 90 (2025 AHA/ACC keeps the 2017 categories). "Prehypertension" is outdated
• Confirm hypertension with home or ambulatory monitoring; white coat hypertension is high only in the clinic
• Kussmaul = metabolic acidosis; Cheyne-Stokes = cyclic breathing with apnea
• Orthostatic hypotension: drop ≥ 20 systolic or ≥ 10 diastolic within 3 minutes of standing