Pediatric Vital Signs and Age-Based Norms —

Pediatric vital signs differ from adult values and shift as the child grows. This note reviews age-specific norms for heart rate, respiratory rate, blood pressure, temperature, and oxygen saturation, along with clinical considerations and common exam traps.

Definition

Pediatric vital signs include heart rate, respiratory rate, blood pressure, temperature, and oxygen saturation.
Normal ranges vary by age: the younger the child, the higher the heart rate and respiratory rate.
Blood pressure increases with age.

Vital Signs by Age

Age	Heart Rate (bpm)	Respiratory Rate (breaths/min)	Blood Pressure (mmHg)
Infant (0–12 months)	100–160	30–60	70–100 / 50–70
Toddler (1–3 years)	90–150	24–40	80–110 / 50–80
Preschool (3–5 years)	80–140	22–34	90–110 / 60–75
School-age (6–12 years)	70–120	18–30	95–115 / 60–75
Adolescent (12–18 years)	60–100	12–20	110–130 / 65–85

Heart Rate

Highest in infancy; decreases with age due to high metabolic demand and a developing cardiovascular system.
Sleeping rates are lower than awake rates — document the patient's state.
Crying and agitation elevate heart rate; allow the child to calm first.
Fever increases heart rate by ~10 bpm per °C (normal compensatory response).
Bradycardia (below normal for age) requires evaluation, especially in infants.
Tachycardia (above normal for age) may indicate fever, pain, dehydration, or respiratory distress.

Respiratory Rate

Highest in infancy; decreases with age.
Infants are obligate nose breathers until ~4–6 months — nasal congestion can cause significant respiratory distress.
Abdominal breathing is normal in infants and young children; the diaphragm is the primary muscle of breathing.
Tachypnea is an early sign of respiratory distress — do not wait for cyanosis to intervene.
Bradypnea is a late sign of respiratory failure and requires immediate intervention.
Count respirations for a full minute in children, as irregular patterns are common.

Blood Pressure

Increases with age; adolescents approach adult norms.
Routine BP measurement should begin at age 3 years.
Hypotension = systolic BP below the 5th percentile for age; it is a late sign of shock. Do not wait for hypotension to intervene.
Hypertension = BP above the 95th percentile for age, sex, and height — requires evaluation.
Correct cuff size is essential: the bladder should cover 80–100% of arm circumference.
- A cuff that is too small → falsely high reading.
- A cuff that is too large → falsely low reading.
Measure in a calm, quiet environment; crying and movement elevate readings.

Temperature

Route	Normal Range	Key Points
Axillary	36.5–37.5°C (97.7–99.5°F)	Least accurate; safe for all ages
Tympanic	36.5–37.5°C (97.7–99.5°F)	Rapid; affected by cerumen or ear infection
Rectal	36.6–38.0°C (97.9–100.4°F)	Gold standard; most accurate

Rectal temperature is the gold standard in infants and reflects core body temperature.
Fever in infants under 3 months = rectal temp ≥ 38°C (100.4°F) → requires immediate medical evaluation due to risk of serious bacterial infection.
Axillary temp is ~0.5°C (0.9°F) lower than rectal.
Tympanic temp is rapid and non-invasive but may be affected by cerumen or otitis media.

Oxygen Saturation

Normal SpO2 is 95–100% in healthy children; values <95% require evaluation for respiratory or cardiac causes.
Children with congenital heart disease may have a lower baseline SpO2 — know the baseline to interpret changes.
Pulse oximetry may be affected by poor perfusion, motion, nail polish, and dark skin pigmentation; correlate with clinical signs.
A normal SpO2 does not rule out respiratory distress — always assess work of breathing.

Common Exam Traps

Do not apply adult normal ranges to children — pediatric values are age-specific.
Do not ignore tachypnea — it is an early sign of respiratory distress.
Do not wait for hypotension to recognize shock — it is a late sign.
Do not use a BP cuff that is too small — it gives a falsely high reading.
Do not assume a crying child's vital signs are accurate — allow the child to calm.
Do not forget that infants are obligate nose breathers — nasal congestion requires intervention.
Do not ignore fever in infants under 3 months — requires immediate evaluation.
Remember: heart rate and respiratory rate decrease with age, while blood pressure increases with age.

Key takeaways

Infants have the highest heart and respiratory rates; values normalize toward adult ranges with age.
Hypotension is a late sign of shock in children — intervene based on earlier signs like tachypnea and tachycardia.
Fever raises HR by ~10 bpm per °C — a normal compensatory response.
Correct BP cuff size is critical: too small reads high, too large reads low.
Infants under 3 months with a rectal temp ≥38°C (100.4°F) require immediate evaluation.
Tachypnea is an early warning sign of respiratory distress — do not wait for cyanosis.