Newborns (Birth to 1 Month)
Newborns present with the fastest heart rates and respiratory rates of any age group. Normal heart rate ranges from 120 to 160 beats per minute. Respiratory rate is typically 30 to 60 breaths per minute. Systolic blood pressure ranges from 60 to 80 mmHg. SpO2 should be maintained at 95% or above, though values of 90 to 95% may be acceptable in the first few minutes after birth as the transition from fetal circulation occurs. Newborns are obligate nose breathers, so nasal congestion can cause significant respiratory distress.
Infants (1 Month to 1 Year)
Infants maintain elevated heart rates compared to adults, with a normal range of 100 to 160 beats per minute. Respiratory rate is typically 25 to 50 breaths per minute. Systolic blood pressure ranges from 70 to 95 mmHg. A quick formula for minimum acceptable systolic BP in infants is 70 mmHg plus twice the age in months. SpO2 should remain at 95% or higher. Bradycardia in infants is almost always caused by hypoxia rather than a primary cardiac event, making airway management the top priority.
Children (1 to 5 Years)
Children in this age group have a normal heart rate of 80 to 140 beats per minute. Respiratory rate is typically 20 to 30 breaths per minute. Systolic blood pressure ranges from 80 to 110 mmHg. The minimum acceptable systolic BP can be estimated as 70 mmHg plus twice the age in years. SpO2 should be at 95% or above. Tachycardia is often the first sign of shock in children before blood pressure changes become evident. Children compensate well until sudden decompensation occurs.
Adolescents (6 to 12 Years)
Adolescents begin to approach adult vital sign values. Normal heart rate is 70 to 120 beats per minute. Respiratory rate is typically 15 to 20 breaths per minute. Systolic blood pressure ranges from 90 to 120 mmHg. SpO2 should remain at 95% or higher. As children grow older, their vital sign ranges narrow and more closely resemble adult norms. Minimum acceptable systolic BP can be estimated as 70 mmHg plus twice the age in years.
Adults (13 Years and Older)
Adult normal heart rate ranges from 60 to 100 beats per minute. Respiratory rate is typically 12 to 20 breaths per minute. Systolic blood pressure is normally 90 to 140 mmHg, with diastolic blood pressure of 60 to 90 mmHg. SpO2 should remain at 95% or above. A heart rate below 60 is classified as bradycardia, and above 100 as tachycardia. Hypotension is generally defined as systolic BP below 90 mmHg. In elderly patients, baseline blood pressure may be higher, so a relative drop of 20 to 30 mmHg from their normal may indicate hypotension even if the reading appears within standard range.
Key Clinical Considerations
Always trend vital signs over time rather than relying on a single measurement. A vital sign within normal range does not rule out pathology if the patient is symptomatic. Consider the patient's baseline and medications when interpreting values. Beta blockers can mask tachycardia in shock. Pulse oximetry may be unreliable in patients with poor perfusion, carbon monoxide exposure, or hypothermia. Document the time of each vital sign assessment and note any interventions performed between measurements.