Pediatric Asthma Score (PAS)

Why use it

Acute asthma exacerbations are among the most common pediatric emergency presentations, responsible for over 600,000 ED visits per year in the US. Objective severity scoring is essential because clinical assessment of asthma severity by subjective inspection alone is unreliable. The PAS provides a structured, reproducible framework enabling consistent severity classification by nurses, pediatric emergency physicians, and trainees, supporting timely initiation of evidence-based treatment and appropriate disposition decisions.

About

The Pediatric Asthma Score (PAS) is a validated bedside clinical scoring tool used to assess the severity of acute asthma exacerbations in pediatric patients (typically ages 2–18 years). The PAS evaluates five clinical parameters: respiratory rate (age-adjusted), oxygen saturation on room air, auscultatory findings (air entry and wheezing), use of accessory muscles (retractions), and dyspnea (work of breathing). Each parameter is scored 1–3, generating a total score of 5–15. Scores are categorized as mild (5–7), moderate (8–11), and severe (12–15) exacerbations, corresponding to the degree of bronchoconstriction and respiratory compromise. The PAS is used to guide initial treatment intensity, assess response to bronchodilator therapy, and determine disposition (discharge, observation, or hospital admission). It is one of several validated pediatric asthma scoring tools; others include the PRAM (Pediatric Respiratory Assessment Measure) and the Pulmonary Score. The PAS has been validated in emergency department settings and shows good inter-rater reliability (ICC 0.84–0.89).

When to use

• All pediatric patients (ages 2–18) presenting to the ED or urgent care with acute asthma exacerbation
• Initial assessment upon arrival — before and after each treatment cycle (albuterol/salbutamol administration)
• Serial assessment every 20 minutes during acute bronchodilator therapy to track treatment response
• Deciding disposition: discharge (PAS <8 after treatment), observation, or hospital admission (PAS ≥8 after maximum treatment)
• NOT validated in infants <2 years (bronchiolitis or viral wheeze — use RDAI or clinical assessment)
• NOT intended to replace clinical judgment in cases of impending respiratory failure or silent chest

Formula

Pearls & pitfalls

• The PAS respiratory rate thresholds are AGE-ADJUSTED — a rate of 30 bpm is normal in a 2-year-old but tachypneic in a 10-year-old. Always use the age-appropriate thresholds.
• SpO₂ <90% on room air (score 3 for oxygenation) is a red flag for severe hypoxemia and should prompt immediate escalation regardless of other PAS components.
• A "silent chest" (no wheeze on auscultation in a patient with severe distress) is actually more severe than audible wheeze — it indicates near-complete airflow obstruction. This is NOT captured well in any scoring system — recognize clinically and escalate immediately.
• After 3 albuterol treatments (60 minutes), reassess PAS. A PAS improvement to <8 predicts safe discharge; persistent PAS ≥8 after 3 doses predicts need for hospitalization.
• Ipratropium bromide (anticholinergic) should be added to the first 3 albuterol treatments in moderate-severe exacerbations — it provides additive bronchodilation and reduces hospitalization rates.
• IV magnesium sulfate (25 mg/kg, max 2g over 20 minutes) is a first-line adjunct for severe acute asthma and reduces hospitalization by approximately 30% in randomized trials.
• Corticosteroids should be given within the first hour of ED presentation for moderate-severe exacerbations — oral prednisolone is as effective as IV methylprednisolone in children who can swallow.
• Serial PAS assessment is more informative than a single assessment — trajectory (improving vs. worsening) is key to disposition decisions.

Next steps

PAS 5–7 (Mild): Albuterol 2.5–5 mg (or 0.15 mg/kg) via nebulizer every 20 minutes × 3 doses (or MDI with spacer 4–8 puffs). Oral prednisolone 1–2 mg/kg (max 40 mg). Reassess PAS after each treatment cycle. If good response: discharge with albuterol MDI, action plan, and follow-up within 1–2 days. PAS 8–11 (Moderate): Continuous or frequent albuterol (every 20 min × 3, or continuous 0.5 mg/kg/h). Ipratropium bromide (250–500 mcg) added to first 3 doses. IV/IM corticosteroid (methylprednisolone 1–2 mg/kg). Consider IV magnesium sulfate 25–40 mg/kg if inadequate response. Monitor SpO₂ continuously. Admission likely if PAS remains ≥8. PAS 12–15 (Severe): PICU consideration; heliox; IV magnesium 25–75 mg/kg (max 2g) over 20 minutes; continuous albuterol; IV aminophylline in refractory cases; non-invasive ventilation if needed; intubation as last resort.

Evidence

Gorelick MH et al. Performance of a novel clinical score, the Pediatric Asthma Severity Score (PASS), in the evaluation of acute asthma. Acad Emerg Med. 2004;11(1):10-18. PMID:14709424. Inter-rater reliability ICC 0.84–0.89 for validated pediatric asthma scoring systems. Global Initiative for Asthma (GINA) 2023 pediatric guidelines. NAEPP Expert Panel Report 3 (2007) severity classification.

References

1. Gorelick MH et al. Performance of a novel clinical score, the Pediatric Asthma Severity Score (PASS), in the evaluation of acute asthma. Acad Emerg Med. 2004;11(1):10-18. — link
2. Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention. 2023. — link
3. National Heart, Lung, and Blood Institute. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma (EPR-3). 2007. — link