Dyspnea or shortness of breath is a common chief complaint among emergency department patients.

Assessment varies based on the severity of the dyspnea and need for intervention.

Differential diagnosis

There are many (some life-threatening) causes of acute dyspnea and they can be organized by system as follows (Table 1):

Establish severity of airway patency and ventilation status and manage accordingly.¹

• Mental status: Decreased LOC, agitation, or altered mental status.
• Respiratory status:
  • Cyanosis.
  • Tiring – Inability to maintain respiratory effort, slow RR is a terminal event.
  • Inability to speak in full sentences.
  • Increased work of breathing: accessory muscle use, profound diaphoresis.
  • Audible stridor, wheezing from obstruction or bronchospasm.
  • Sitting in tripod position, unable to lie supine.
• Signs of an allergic reaction.
• Vital signs:
  • Pulse oximetry:
    • inaccurate in cases of hypothermia, shock, carbon monoxide poisoning, and methemoglobinemia.
    • SpO2 should be >95% for healthy individuals.
    • 92-95% for patients who are older, smoke or are obese.
    • can be <92% for patients with severe chronic lung disease.
  • BP – Hypotension may indicate sepsis / shock picture.
  • HR – tachyarrhythmias rarely can lead to dyspnea and tachycardia can be a finding in PE but are more commonly tachycardia is secondary to the cause of the dyspnea.

Once stabilized/if stable: Determine etiology to guide management

Acute dyspnea (over minutes to hours) has a relatively limited number of causes, including:

• ACS.
• HF.
• Cardiac tamponade.
• Bronchospasm.
• PE.
• Pneumothorax.
• Infection.
• Massive pleural effusion – blood or effusion.
• Upper airway obstruction.
• ARDS.

Past medical history often leads to most likely diagnosis but beware of two conditions: ie. PE or pneumonia in COPD or PTX in asthma exacerbations.

Historical features can help:

• Chest pain – ACS, PE, pneumothorax etc.
• Fever – pneumonia, aspirin poisoning, etc.
• Paroxysmal nocturnal dyspnea (PND) – HF, COPD (asthma or GERD).
• Hemoptysis – severe valvular disease (e.g., mitral stenosis), PE, tuberculosis, malignancy.
• Cough / sputum – white or pink frothy sputum (HF), purulent sputum (pneumonia), nonproductive cough (asthma, heart failure, respiratory infection, or PE).
• Trauma – pneumothorax, hemothorax, cardiac tamponade.
• Wheezing – bronchospasm, foreign body, pulmonary edema.

Physical examination includes an appropriate examination of respiratory, cardiovascular, skin, and extremities.²

CXR and ECG should be obtained in most patients who present to ED with acute dyspnea.

CXR: can help in the diagnosis of:

• Acute HF – Ultrasound is more sensitive than CXR.³
• Pneumonia.
• Pneumothorax.
• COPD / asthma complication such as pneumothorax or pneumonia.

ECG: can help in the diagnosis of:

• cardiac ischemia.
• PE.
• pericardial effusion.
• old ECG helpful for comparison.

Ultrasound: Immediate use of point-of-care ultrasound (POCUS) in combination with standard work-up of dyspneic patients in ED can help improve the accuracy of diagnosis.⁴ Combined heart, lung, and IVC ultrasound has overall high specificity and lower sensitivities for etiologies of acute dyspnea in the emergency department and has a good correlation with diagnosis determined by the emergency physician.⁵

•  Lung views: help with diagnosis of:
  • Pneumothorax.
  • Pulmonary edema.
  • Pleural effusions.
  • Pneumonia.
• Cardiac views: to assess right heart strain, global cardiac dysfunction, focal wall motion abnormalities, and help diagnose pericardial effusion. Overall, echocardiography has a low sensitivity for diagnosing PE. Accuracy is higher in diagnosis of massive PE. Regional wall motion abnormalities sparing the RV apex (McConnell’s sign) are particularly suggestive of PE.⁶
• IVC views: collapsible IVC helps rule out obstructive shock (PE, pericardial effusion, tension pneumothorax).

Lab

• Cardiac biomarkers
  • serial troponin to help rule out ACS.
  • not specific to ACS, can be elevated in PE, sepsis, pericarditis, myocarditis, etc.
• BNP
  • Limited role but if elevated, can help diagnose HF.
  • Non-specific – can be elevated in renal failure, ACS, PE, etc.
• D-dimer
  • To rule out PE in patients with a low probability of PE (Wells score 0-1).
  • Non-specific – can be elevated in malignancy, recent surgery, pregnancy, etc.
• Blood gas
  • Venous BG and serum bicarbonate – to determine the acid-base status of the patient or need for more aggressive management.
  • Methemoglobin and CO levels can also be added.
• Consider ASA overdose

Other investigations

• CT chest / VQ scan
  • CT chest can help diagnose
    • Malignancy.
    • Pneumonia.
    • PE (patients with moderate to high probability of PE, who are not suitable for d-dimer, should receive a CTPE).
  • Ventilation-perfusion (V/Q) scanning – alternative method for diagnosing PE in patients unsuitable for CTPE.
• Peak expiratory flow (PEF) rate
  • to help distinguish pulmonary and cardiac causes of dyspnea.
  • to determine severity of bronchoconstriction severe asthma.

1. Retractions www.nlm.nih.gov/medlineplus/ency/article/003322.htm (Accessed on February 02, 2006).

   
   

2. Wipf JE, Lipsky BA, Hirschmann JV, et al. Diagnosing pneumonia by physical examination: relevant or relic? Arch Intern Med 1999; 159:1082.

   
   

3. Collins SP, Lindsell CJ, Storrow AB, et al. Prevalence of negative chest radiography results in the emergency department patient with decompensated heart failure. Ann Emerg Med 2006; 47:13.

   
   

4. Pirozzi, Concetta, et al. “Immediate versus delayed integrated point-of-care-ultrasonography to manage acute dyspnea in the emergency department.” Critical ultrasound journal 6.1 (2014): 1-8.

   
   

5. Zanobetti M, Scorpiniti M, Gigli C, Nazerian P, Vanni S, Innocenti F, et al. Point-of-Care Ultrasonography for Evaluation of Acute Dyspnea in the ED. Chest. 2017 Jun;151(6):1295-1301. doi: 10.1016/j.chest.2017.02.003. Epub 2017 Feb 16. PMID: 28212836.

   
   

6. Sosland, Rachel P., and Kamal Gupta. “McConnell’s Sign.” Circulation 118.15 (2008): e517-e518.

   
   

1. POCUS use in the diagnosis of acute dyspnea in ED