Suspect in any acute dyspnea with unilateral findings, trauma, COPD/asthma exacerbation, post-procedure (central line, thoracentesis), or barotrauma on positive-pressure ventilation.
Reassess at each step: peak flow / FEV₁, work of breathing, SpO₂, ETCO₂, mental status. Advance one rung every 15–20 min if no improvement (or sooner if deteriorating).
Mild — speaking full sentences, SpO₂ ≥ 95%, PEF > 70% predicted
Moderate — partial sentences, accessory-muscle use, PEF 50–70%
Severe — single-word dyspnea, PEF < 50%, SpO₂ < 92% on O₂
Refractory severe — fatigue, normal/rising ETCO₂ in asthmatic
Impending arrest — silent chest, cyanosis, AMS, bradycardia
De-escalation: once PEF > 70% predicted and SpO₂ ≥ 95% on RA × 1 h, space nebs to q1–4 h PRN, complete 5-day steroid course, ensure inhaler technique + follow-up before discharge.
Stridor + worsening perfusion = upper-airway obstruction crossing into shock. Escalate one step every 5–10 min if vitals deteriorate (SpO₂ ↓, HR ↑↓, BP ↓, AMS, mottling).
SpO₂ ≥ 94%, normal HR/BP, no AMS
Tachypnea, mild retractions, SpO₂ 90–94%
Severe retractions, fatigue, RR ↓, HR ↑↑, cap refill ≥ 3 s, cool extremities
Silent chest, cyanosis, AMS, SBP < 5th %ile, bradycardia
Transition trigger to next step: any worsening vital (HR, RR, SpO₂, BP, mental status) within 5–10 min of intervention. Document time-stamped reassessments.