What are the normal vital signs for infants and children?

Normal Vital Signs in Infants and Children

For infants and children, heart rate ranges from 107-182 bpm in neonates (7-30 days), decreasing to 113 bpm by age 2 years, while respiratory rate declines from a median of 44 breaths/min at birth to 26 breaths/min by age 2 years. 1, 2, 3

Heart Rate Parameters by Age

Neonates and Young Infants

• First week of life: 91-166 bpm 1
• 7-30 days: 107-182 bpm (mean 149 bpm) 1, 2
• 1-3 months: 121-179 bpm 1

Older Infants and Children

• Heart rate peaks at approximately 1 month of age, reaching a maximum of 145 bpm before declining 3
• By 2 years: median 113 bpm 3
• Heart rate continues to decline gradually through early adolescence 3

Respiratory Rate Parameters by Age

• Birth: median 44 breaths/min 3
• 2 years: median 26 breaths/min 3
• The steepest decline occurs in infants under 2 years of age 3
• Respiratory rate continues to decrease from birth through early adolescence 3

Blood Pressure Parameters

• Hypertension is defined as systolic or diastolic blood pressure at or above the 95th percentile for age, height, and sex 1
• Blood pressure should be measured after 5 minutes of rest, with the patient seated and right arm supported at heart level 1
• For children <12 years, Pediatric Advanced Life Support definitions fit best with population-based lower centiles 4
• For children >12 years, Parshuram's early warning score cut-offs agree better with the 5th percentile than other guidelines 4

Critical Thresholds Requiring Immediate Action

Bradycardia

• Heart rate <60 bpm with signs of poor perfusion requires immediate CPR and chest compressions 1, 2
• This threshold indicates imminent cardiac arrest 1

Hypotension

• Hypotension with capillary refill >3 seconds indicates more severe shock than isolated tachycardia 1, 2
• Altered mental status, poor peripheral perfusion, or weak pulses warrant immediate evaluation regardless of specific vital sign values 1, 2

Respiratory Support

• Provide rescue breathing at 1 breath every 2-3 seconds (20-30 breaths/min) if pulse is present but breathing is absent or inadequate 1

Important Clinical Pitfalls to Avoid

Normal Physiologic Variations

• Do not misinterpret transient bradycardia during feeding, sleep, or defecation as pathological—these represent normal vagal tone increases 1, 2
• Using 2nd and 98th percentiles means 4% of normal infants will have values outside these ranges 2

Abnormal Values Requiring Investigation

• Heart rates below the lower normal limit (e.g., <107 bpm in infants 7-30 days) may indicate CNS abnormalities, hypothermia, increased intracranial pressure, meningitis, or hypothyroidism 1, 2
• Heart rates above the upper normal limit (e.g., >182 bpm in infants 7-30 days) may indicate fever, infection, anemia, pain, dehydration, hyperthyroidism, or myocarditis 1, 2
• Persistent tachycardia or bradycardia requires investigation for underlying causes 1, 2

Key Considerations for Clinical Practice

• Current reference ranges used in many clinical guidelines show striking disagreement with evidence-based centiles, with published limits frequently exceeding the 99th and 1st centiles 3
• Vital signs should be documented in kilograms for weight, with a full set including temperature, heart rate, and respiratory rate 4
• A process should be in place for identifying abnormal vital signs according to the age of the patient and notifying the physician of abnormal values 4
• Blood pressure and pulse oximetry monitoring should be available for children of all ages based on illness and injury severity 4