Vital signs are the first warning system in nursing. A rising respiratory rate, a falling blood pressure or a new confusion is often the earliest sign that a patient is deteriorating, hours before a cardiac arrest. This guide gives the normal ranges for every age group, explains how to measure each sign accurately, and sets out when to escalate.
Ranges vary slightly between references and local policies. Always follow your hospital’s early warning score and your national guidelines.
Normal vital signs in adults
| Vital sign | Normal adult range | Notes |
|---|---|---|
| Heart rate (pulse) | 60–100 beats per minute | Fit adults and athletes may sit at 50–60 at rest |
| Respiratory rate | 12–20 breaths per minute | The most sensitive early sign of deterioration |
| Blood pressure | Below 120/80 mmHg is considered normal | Systolic below 90 or a big drop from baseline is a warning sign |
| Temperature | About 36.1–37.2°C | 38°C or above is fever; below 36°C may signal sepsis or hypothermia |
| Oxygen saturation (SpO₂) | 94–98% on air | 88–92% target in patients at risk of hypercapnic respiratory failure (e.g. some COPD), as prescribed |
| Level of consciousness | Alert | Any new confusion is significant |
| Pain | As reported by the patient | Often called the “fifth vital sign” |
Normal vital signs in children and infants
Children are not small adults. Their heart and breathing rates are faster, and they compensate well until they suddenly don’t. These are typical resting ranges:
| Age | Heart rate (bpm) | Respiratory rate (breaths/min) |
|---|---|---|
| Newborn (0–1 month) | 100–160 | 30–60 |
| Infant (1–12 months) | 100–160 | 30–50 |
| Toddler (1–2 years) | 90–150 | 24–40 |
| Preschool (3–5 years) | 80–140 | 22–34 |
| School age (6–12 years) | 70–120 | 18–30 |
| Adolescent (13+ years) | 60–100 | 12–20 |
Blood pressure in children depends on age, sex and height, so judge it against centile charts rather than a single number. In children, low blood pressure is a late and ominous sign. A rising heart rate, a prolonged capillary refill (over 2 seconds), cool peripheries and reduced urine output usually come first.
How to measure each vital sign accurately
Respiratory rate
- Count for a full 60 seconds, ideally without telling the patient, since people change their breathing when watched.
- Note the depth and pattern, use of accessory muscles, and whether the patient can speak in full sentences.
- It is the most commonly skipped or estimated sign, and one of the most important. A rate above 24 in an adult should worry you.
Pulse
- Feel the radial pulse for 30 seconds and double it if regular. Count for 60 seconds if irregular.
- Note the rhythm and volume, not just the rate. A weak, thready pulse suggests shock.
- For infants, use the brachial or apical pulse.
Blood pressure
- Use the right cuff size. A cuff that is too small gives falsely high readings, and one that is too large gives falsely low ones.
- Seat or lie the patient with the arm supported at heart level, after five minutes’ rest where possible.
- Recheck any abnormal automated reading manually.
Temperature
- Use the same route each time and document it (tympanic, oral, axillary or rectal for neonates if your policy allows).
- Older adults and patients who are immunosuppressed may not mount a fever even with severe infection.
Oxygen saturation
- Make sure the probe has a good waveform. Cold hands, nail varnish and movement give false readings.
- Pulse oximeters can overestimate saturation in patients with darker skin, so look at the whole patient, not just the number.
- Always record whether the patient is on air or oxygen, and how much.
Red flags: when to escalate immediately
- Respiratory rate of 25 or more, or 8 or below.
- Systolic blood pressure of 90 mmHg or below, or a fall of more than 40 from the patient’s usual.
- Heart rate of 131 or more, or 40 or below.
- SpO₂ of 91% or below on air (outside a prescribed lower target).
- New confusion or reduced consciousness.
- Temperature of 39.1°C or above, or 35°C or below.
- Your own gut feeling that the patient is “not right”. Trust it and escalate.
These thresholds trigger the highest single-parameter scores in early warning systems such as NEWS2, used across the UK and in many hospitals worldwide. When you escalate, use SBAR so the doctor gets the key information in under a minute.
Trends matter more than single readings
A heart rate of 98 is “normal”. But a heart rate that has climbed from 72 to 98 over four hours, with the respiratory rate rising from 16 to 22, tells a story, often sepsis or bleeding. Chart every set of observations, look at the trend and compare with the patient’s baseline. Many patients who arrest in hospital show abnormal vital signs in the hours before.
Documentation tips
- Record the time, the values, the route (for temperature) and the oxygen delivery.
- Calculate the early warning score every time, and act on it.
- Write down who you escalated to, when, and what they advised.
- Never record observations you did not take.
Keep learning: Sepsis recognition and the Sepsis Six · Glasgow Coma Scale explained · Drug calculation formulas
Based on Royal College of Physicians NEWS2 guidance, American Heart Association blood pressure categories, British Thoracic Society oxygen guidance and standard paediatric reference ranges. Educational content: follow your local policy.