01Purpose and principlesWhat the assessment is for and the core concepts behind it.
Paediatric reference ranges are age dependent and continuous. RCUK 2025 provides approximate lower and upper limits at 1 month, 1, 2, 5, 10 and 18 years and advises intermediate values between those ages. These are emergency reference values, not population centiles for every purpose. National PEWS charts use defined age bands and escalation rules. Use the chart adopted by the organisation while retaining clinical judgement when a child sits close to a boundary or has a known abnormal baseline.
Respiratory rate is often the earliest abnormal observation. Count before touching the chest or causing crying, ideally for a full 60 seconds in infants because breathing is irregular. Watch abdominal and chest movement and record apnoea, grunting, recession, nasal flare and pattern. At 1 month the approximate RCUK range is 25–60/min; it narrows progressively to 12–20/min by 18 years. A high rate may reflect fever, pain, acidosis or lung disease; a low or falling rate with drowsiness suggests central depression or exhaustion.
Heart rate also falls with age. Approximate RCUK limits are 110–180/min at 1 month, 100–170 at 1 year, 90–160 at 2 years, 70–140 at 5 years, 60–120 at 10 years and 60–100 at 18 years. Count an irregular infant pulse for a full minute and correlate monitor rate with a palpable pulse. Fever, distress, dehydration and beta-agonists cause tachycardia; pain treatment and settling should improve a physiological rise. Disproportionate, abrupt or fixed tachycardia raises arrhythmia.
Blood pressure rises with age and height. Use the correct cuff: bladder width about 40% of arm circumference and length covering 80–100% of the arm. A cuff that is too small overestimates and one too large may underestimate. RCUK median systolic values are about 75 mmHg at 1 month, 95 at 1 year, 98 at 2 years, 100 at 5 years, 110 at 10 years and 120 at 18 years. Fifth-centile values are about 50, 70, 73, 75, 80 and 90 mmHg respectively.
The blood-pressure table exposes why one adult cutoff is unsafe. A systolic pressure of 78 mmHg may be above the fifth centile at age 2 but below it at age 10. Even an age-normal pressure can coexist with shock because vasoconstriction preserves it until compensation fails. Assess central and peripheral pulses, skin temperature, capillary refill, consciousness, urine output and lactate. Repeat a surprising automated reading manually while resuscitation continues if the phenotype is concerning.
Oxygen saturation requires a pulsatile waveform, an appropriate probe and warm perfused site. Motion, cold limbs, nail products, venous pulsation and dyshemoglobinaemia can mislead. For most acutely ill previously healthy children, a persistent saturation below the locally defined normal range requires assessment; RCUK describes 90–93% in air as mild-to-moderate hypoxaemia and below 90% as severe. Do not force a normal target on a child with a documented cyanotic congenital-heart baseline; use the specialist target and assess change.
Temperature depends on site and device. Record the method because axillary, tympanic and core values are not interchangeable. NICE advises electronic axillary measurement below 4 weeks and electronic axillary or infrared tympanic measurement from 4 weeks to 5 years in healthcare settings. Fever of at least 38°C under 3 months is high risk; at 3–6 months, at least 39°C is at least intermediate risk. Hypothermia can also signal serious infection, environmental exposure or metabolic failure.
Capillary refill is measured by pressing a central site such as sternum for about five seconds and timing colour return, with adequate lighting and temperature. NICE includes refill of 3 seconds or longer as an abnormal feature in febrile under-5s. Cold environment, skin pigmentation, lighting and technique affect interpretation. Combine it with pulses, skin temperature and mental state. A normal value after compensation or early sepsis does not cancel other circulatory evidence.
Consciousness and behaviour are physiological observations. Record AVPU and interaction, tone, consolability, speech or cry. A toddler who stops playing or an infant who no longer fixes and follows may be deteriorating before a formal score changes. Pain, sleep and neurodevelopment affect assessment, so compare with baseline and caregiver observation. A new response only to voice or pain is an emergency airway and neurological concern.
Urine output integrates perfusion, intake and renal function but often lags. Weigh nappies when accurate measurement matters, using 1 g weight gain as approximately 1 mL urine. Common minimum targets are around 2 mL/kg/hour in infants, 1 in children and 0.5 in adolescents, although local critical-care definitions and renal conditions vary. Oliguria with tachycardia, poor perfusion or rising creatinine is more concerning than an isolated missed void after limited intake.
Always annotate context: asleep or awake, calm or crying, febrile, post-exercise, on oxygen, after salbutamol, analgesia or fluid and measurement site. Repeat after correcting artefact or treating distress. A trajectory across several observations is more powerful than a score at one time. Escalate if clinician or family concern persists, because PEWS complements rather than replaces recognition of abnormal appearance or rapid change.
Key points
- Measure before interpreting: observe a settled child, count respiratory rate for a full minute in infants and use a correctly sized blood-pressure cuff and reliable saturation waveform.
- RCUK 2025 approximate respiratory-rate ranges are 25–60/min at 1 month, 20–50 at 1 year, 18–40 at 2 years, 17–30 at 5 years, 14–25 at 10 years and 12–20 at 18 years.
- RCUK 2025 approximate heart-rate ranges are 110–180/min at 1 month, 100–170 at 1 year, 90–160 at 2 years, 70–140 at 5 years, 60–120 at 10 years and 60–100 at 18 years.
- Median systolic pressure rises with age: approximately 75 mmHg at 1 month, 95 at 1 year, 98 at 2 years, 100 at 5 years, 110 at 10 years and 120 at 18 years.
- The RCUK fifth-centile systolic values are approximately 50 mmHg at 1 month, 70 at 1 year, 73 at 2 years, 75 at 5 years, 80 at 10 years and 90 at 18 years.
- Use intermediate values between table ages and the National PEWS chart assigned to the child's age band; physiology changes continuously rather than on birthdays.
- Crying, pain, fever, exercise and anxiety can raise pulse and respiratory rate, but persistent abnormality after settling or analgesia still needs explanation.
- A normal blood pressure does not exclude compensated shock; interpret pulses, refill, skin temperature, mental state and urine together.
- Capillary refill longer than 3 seconds is abnormal in NICE fever assessment when measured centrally under appropriate conditions, but normal refill cannot exclude shock.
- Healthy children at sea level generally have saturation 95% or higher, but check signal quality and use the prescribed baseline target in congenital cyanotic heart or chronic respiratory disease.
- Urine output is a perfusion trend: commonly seek about 2 mL/kg/hour in infants, 1 mL/kg/hour in children and 0.5 mL/kg/hour in adolescents, interpreted with renal and fluid context.
- Trend and clinical pattern outweigh an isolated borderline reading; document state, oxygen, device, site and interventions with each set.
02Indications, selection and cautionsWhen it is useful, when urgency changes and important limitations.
A pulse must be compared with age, temperature, pain and trend before it is labelled physiological or pathological.
A previously rapid rate that falls alongside reduced effort, air entry or consciousness signals decompensation rather than normalisation.
Normal blood pressure with tachycardia, cool skin, weak peripheral pulses or delayed refill still represents possible shock.
Persistent low saturation with a good waveform, compatible respiratory findings and a warm probe site is more credible than one motion-affected number.
The same temperature carries different risk below 3 months, at 3–6 months and in an older child.
A value inside a population range may be abnormal for a child with chronic disease or a clear personal trend.
03Method and interpretationA systematic approach to the test and its findings.
Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.
- 01
First-line: respiratory rate and effortFirst stepFirst line - Why
- Detect early respiratory or metabolic stress and later fatigue.
- Interpretation and limitations
- Compare with the RCUK age range and record effort, pattern, state and trend; rate alone cannot distinguish compensation from failure.
- 02
First-line: pulse and perfusionFirst line - Why
- Assess cardiovascular compensation and possible arrhythmia.
- Interpretation and limitations
- Relate rate to age, fever, pain, rhythm, pulses, refill, skin and consciousness; bradycardia in an unwell hypoxic child is late.
- 03
Blood pressure with correct cuff - Why
- Identify late shock, hypertension and response to treatment.
- Interpretation and limitations
- Compare with age-specific centiles and clinical perfusion; repeat an unexpected oscillometric value manually with correct technique.
- 04
Pulse oximetry - Why
- Screen oxygenation and follow respiratory support.
- Interpretation and limitations
- Accept only a stable waveform and appropriate probe; compare with prescribed baseline in cyanotic or chronic disease.
- 05
Temperature by documented method - Why
- Identify fever or hypothermia and apply age-specific infection risk.
- Interpretation and limitations
- Use NICE-recommended devices for young children and interpret 38°C below 3 months as high risk.
- 06
National PEWS and trajectory - Why
- Standardise observation frequency and escalation across inpatient care.
- Interpretation and limitations
- Follow the age-band chart, but override the aggregate score for severe single-parameter abnormality, clinical concern or rapid change.
04Clinical next stepsHow the result changes management or prompts escalation.
01Routine observationsMeasure under known conditionsFirst stepA child requires a baseline or repeat observation set.+
- 1Settle and observe the child, select age-appropriate probe and cuff and record oxygen and behavioural state.
- 2Measure respiratory rate, pulse, saturation, temperature, perfusion and indicated blood pressure and consciousness accurately.
- 3Plot on the correct PEWS chart and compare with RCUK age ranges, baseline and previous values.
02Unexpected numberVerify without delaying careA reading conflicts with appearance or is physiologically extreme.+
- 1Check probe signal, cuff, site, movement and device and repeat manually when appropriate.
- 2Assess the corresponding ABC domain clinically rather than waiting for repeated machine results.
- 3EscalationTreat and escalate immediately when phenotype is dangerous, documenting the confirmed value and response.
03Abnormal trendEscalate trajectory before collapseEscalationSuccessive observations worsen or require increasing support.+
- 1Repeat ABCDE and identify whether pain, fever, medicines, fluid or disease explains the direction.
- 2EscalationIncrease observation frequency and escalate through the National PEWS and clinical-concern pathway.
- 3State the trend, baseline, interventions and family concern explicitly during senior review and handover.
04Chronic abnormal baselineUse an individual target safelyCongenital cardiac, respiratory, neurological or autonomic disease changes expected observations.+
- 1Retrieve the documented usual range and specialist target rather than accepting an unverified caregiver estimate alone.
- 2Assess relative change, work of breathing, perfusion, interaction and support requirements.
- 3EscalationRecord the agreed target and escalation threshold visibly and seek specialist review for deviation.
05Risks, monitoring and follow-upComplications, safety checks and further assessment.
- Set observation frequency from the sickest domain, trajectory and intervention rather than the convenience of a routine schedule.
- After oxygen, bronchodilator, analgesia, antipyretic or fluid, repeat the observation most likely to change and perform a complete clinical reassessment.
- Monitor work of breathing and consciousness alongside saturation because oxygen therapy can conceal worsening ventilation.
- Trend urine output with intake, weight and renal function and use weighed nappies when precise monitoring is necessary.
- Record the device, cuff, site, state, oxygen flow and reason for an individual target so later values remain interpretable.
- Escalate for parent concern or clinician concern independently of the PEWS total and document who accepted the escalation.
06Special situationsVariants, exceptions and circumstances that change the usual approach.
Ranges are continuous
A child does not acquire a new normal range on a birthday; interpolate and use the chart's age band with judgement.
Blood pressure hides compensation
Vasoconstriction preserves pressure while tissue perfusion declines, making normal pressure a poor rule-out test for early shock.
Context belongs beside the number
Crying, sleep, oxygen and recent medicines can make identical observations mean very different things.
Equipment creates diagnoses
A small cuff, loose saturation probe or motion artefact can manufacture hypertension or hypoxaemia and trigger inappropriate treatment.
One parameter can trump score
Severe hypoxaemia, bradycardia or reduced consciousness requires action even when other observations keep an aggregate score modest.
Baseline is not immunity
A chronically low saturation may be expected, but further fall, increased effort or altered perfusion still signals acute illness.
07Common pitfallsFrequent interpretation and management errors.
- 01
Do not use one adult normal range for all children.
- 02
Do not count infant respirations for only 15 seconds when breathing is irregular.
- 03
Do not accept a saturation without a credible waveform and compatible pulse.
- 04
Do not use a cuff that is too small and then diagnose hypertension.
- 05
Do not wait for hypotension before treating shock.
- 06
Do not interpret falling pulse or respiratory rate as recovery when appearance worsens.
- 07
Do not apply a healthy saturation target to cyanotic congenital heart disease without the individual plan.
- 08
Do not let fever or crying explain persistent marked tachycardia without reassessment.
- 09
Do not allow a low PEWS score to overrule family concern or clinical deterioration.