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Vital signs, with the why: what normal is, and what each number is telling you.

A vital sign is not a number to write down. It is the body reporting on itself. Learn what each one measures and abnormal readings stop being random.

Neurodivergent VitalsUpdated 2026-09-128 min read

The ranges

These are the commonly taught EMT-level ranges. Textbooks differ slightly at the edges, and every patient has a baseline; a marathon runner at 48 beats a minute is fine and a frightened child at 130 may be too. Trend and context beat any single number.

VitalAdultChild (about 1–12)Infant (under 1)
Pulse (per minute)60–100roughly 70–120, faster in younger children100–160
Respirations (per minute)12–20roughly 15–3025–50
Systolic blood pressureabout 90–140roughly 80–110 (a common rule: 70 + 2 × age in years is the low limit)roughly 70–95
Oxygen saturation95–100%95–100%95–100%
Temperatureabout 98.6 °F / 37 °C; fever is generally above 100.4 °F / 38 °C
Blood glucoseroughly 70–120 mg/dL depending on the last meal; below 60–70 with symptoms is hypoglycemia
Pupilsequal, round, reactive to light
Skinwarm, pink (at the mucous membranes in darker skin), dry

What each one is really measuring

Pulse: how hard the pump is working

The heart speeds up for a reason: fear, pain, fever, blood loss, low oxygen. A fast pulse in a calm patient is the body compensating for something. A fast, weak pulse is the body compensating for not enough blood. A slow pulse in a sick patient, especially a child or a head injury, is late and dangerous.

Respirations: rate is half the story

Count the rate, but look at the work. Fast and shallow, use of neck and rib muscles, speaking in short phrases, a child grunting or flaring the nostrils: those are the signs of inadequate breathing regardless of the number. Slow, irregular breathing in an unresponsive patient is a failing brain or an overdose, and it means you breathe for them.

Blood pressure: the late sign

Pressure is what is left after the body has done everything it can: sped the heart up, clamped the vessels down. When pressure finally falls, compensation has run out. That is why a normal blood pressure never rules out shock, and a falling one is an emergency.

Why children fool youChildren compensate ferociously. Their pressure stays normal until they have lost a large fraction of their blood volume, and then it collapses. In a child, trust the pulse, the skin and the mental status long before you trust the cuff.

Oxygen saturation: useful, with limits

SpO2 tells you how saturated the hemoglobin is, not whether there is enough hemoglobin or whether it is carrying the right gas. Carbon monoxide poisoning can read a perfect 100%. Cold fingers, nail polish, shivering and poor perfusion all give false numbers. Treat the patient, then the probe.

Temperature, glucose, pupils, skin

Fever raises every other rate. Low glucose looks like a stroke, intoxication or a behavioral emergency, which is why you check it in every altered patient. Unequal pupils mean pressure on one side of the brain until proven otherwise. Skin is the earliest window into perfusion: cool and pale is the body pulling blood inward; flushed and hot is vessels wide open.

How to use them

  1. Get a full set early, then repeat. Stable patients every 15 minutes, unstable every 5. The trend is the finding.
  2. Compare to the patient's own baseline when you can get it.
  3. Never let one normal number reassure you when the others, or the patient in front of you, say otherwise.
The one thing

Pulse and skin change first. Pressure changes last. If you wait for the blood pressure to tell you someone is in trouble, you have waited too long.

Questions people ask

What are normal vital signs for an adult?

Commonly taught EMT ranges: pulse 60 to 100 per minute, respirations 12 to 20 per minute, systolic blood pressure about 90 to 140, oxygen saturation 95 to 100 percent, temperature about 98.6 °F (37 °C). Individual baselines vary.

What are normal vital signs for an infant?

Infants under one year typically run a pulse of 100 to 160, respirations of 25 to 50, and a systolic blood pressure roughly in the 70s to 90s. Pulse, breathing effort, skin and mental status are more reliable warning signs in infants than the cuff.

Why is blood pressure a late sign of shock?

The body maintains pressure by speeding the heart and constricting vessels. Pressure only falls when those mechanisms are exhausted, so a normal blood pressure does not rule out shock, and a falling one means compensation has failed.

Where this goes

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