Undifferentiated dyspnea (ED)

Call 911 or go to the nearest emergency room right away if you have:

• natural marker of fluid overload (BNP) >400 OR natural marker of fluid overload (NT-proBNP) > age-adjusted cutoff (>450 if <50 y, >900 50-75, >1800 >75) + orthopnea/PND + pulmonary edema on CXR / B-lines on POCUS (Maisel 2002 PMID 12124404; Heidenreich 2022 PMID 35379503)
• Suspected PE + sustained hypotension (SBP <90 ×≥15 min) OR cardiac arrest with PEA/pulseless rhythm OR RV strain on POCUS with positive D-dimer (ESC 2019 PE Konstantinides PMID 35379503)(life-threatening)
• Known COPD + worsening dyspnea + increased sputum + pH <7.35 + PaCO2 >45 on ABG (GOLD 2026)
• Known asthma + peak flow <50% personal best OR FEV1 <50% predicted + accessory muscle use + oxygen level (SpO₂) <92% RA + speaking in short phrases (GINA 2026)
• Sudden pleuritic dyspnea + tracheal deviation + decreased breath sounds + hyperresonance + hemodynamic compromise — bedside diagnosis, do NOT delay for imaging (ATS/CHEST 2010)(life-threatening)
• Bilateral infiltrates on CXR + PaO2/FiO2 ≤300 + non-cardiogenic edema (natural marker of fluid overload (BNP)/natural marker of fluid overload (NT-proBNP) not consistent with HF, or echo without congestion) — Berlin criteria (Ranieri JAMA 2012; ATS/ESICM 2023)(life-threatening)
• Acute onset (minutes-hours) skin/mucosal involvement (urticaria, angioedema, flushing) + ≥1 of: respiratory compromise (stridor, wheeze, hypoxia) OR hypotension OR persistent GI symptoms after likely allergen exposure (WAO 2020; Sampson NIAID criteria)(life-threatening)
• Dyspnea on exertion + pallor + tachycardia + Hb drop / melena / hematemesis (ACG 2021 UGIB)
• Dyspnea with Kussmaul respirations + glucose >250 + anion gap >12 + ketones + bicarb <18 (ADA 2026)
• Dyspnea on exertion + RV failure signs (JVD, peripheral edema, hepatomegaly) + echo RVSP >40 OR RV strain — group 1-5 PH (ESC/ERS 2022 PH guideline)