Acute Dyspnea Study Notes

• Study notes cover acute dyspnea, emphasizing key elements for easier study.

Definition and Initial Assessment

• Dyspnea is a symptom, not a disease, marked by an unpleasant breathing awareness.
• Life-threatening conditions needing immediate intervention are indicated by altered consciousness, inability to maintain respiratory effort, and cyanosis.
• Assessments should evaluate airway permeability, respiratory rate, SpO2, blood pressure, and heart rate.

Signs of Critical Illness

• Polypnea is rapid breathing (> 30 breaths/min); bradypnea is slow breathing (< 8 breaths/min).
• Costal draft (suprasternal, intercostal, subcostal retractions) may be absent in neuromuscular diseases.
• Accessory muscle use suggests respiratory muscle fatigue.
• Other signs include inability to speak in full sentences or lie down, diaphoresis, cyanosis, altered mental status (confusion, agitation, somnolence, convulsions, coma), and arterial hypotension that may progress from initial tachycardia to bradycardia.

Clinical Examination

• Stridor indicates upper airway obstruction.
• Wheezing may indicate asthma, COPD exacerbation, heart failure, or foreign body.
• Diminished or absent breath sounds may indicate pleural effusion, pneumothorax, asthma, or COPD.
• Rales may indicate pneumonia, ARDS, pulmonary fibrosis, or heart failure.
• Chest pain can suggest underlying issues, differentiating between pleuritic and non-pleuritic causes.
• Turgid jugular veins may indicate heart failure, cardiac tamponade, or pulmonary embolism.
• Syncope may indicate AoS, OHCM, arrhythmia, or anemia.
• Hypertension may indicate ACPE, heart failure, AMI, stroke, or panic attack.
• Hypotension may indicate sepsis, metabolic acidosis, pulmonary embolism, or advanced heart failure.
• Hemoptysis may indicate pulmonary embolism, bronchiectasis, pulmonary cancer, tuberculosis, or mitral stenosis.
• Hyperventilation may indicate acidosis, sepsis, salicylate poisoning, or anxiety.
• Orthopnea may indicate acute heart failure or toxic pulmonary edema.
• Peripheral edema may indicate congestive heart failure.
• Paradoxical pulse may indicate severe asthma, pulmonary embolism, or tamponade.

Key Diagnostic Tests

• Chest Radiographs identify pleural effusion, pneumothorax, pneumonia, pulmonary edema, and cardiac silhouette abnormalities.
• 12-lead ECG identifies ischemia, MI, LBBB, LVH, and arrhythmias.
• ABG/Pulse Oximetry assesses oxygenation, ventilation, and acid-base status.
  • Normal ranges: pH (7.36-7.44), pCO2 (40 mmHg), HCO3- (24 mEq/l), pO2 (75-100 mmHg).
• Respiratory Failure is indicated by PaO2 < 60 mmHg + PaCO2 > 45 mmHg.
• Pulse Oximetry normal range is 95-100%.
  • 91-95% requires identification of the cause.
  • ≤ 91% requires emergency evaluation.
  • Conditions such as hypothermia, shock, CO intoxication and methemoglobinemia will cause it to be inaccurate
• Other Tests: Consider ultrasonography, BNP, D-dimer, troponin, and pulmonary CT.

Additional Diagnostic Tests

• Lung Ultrasound differentiates between cardiogenic and non-cardiogenic causes of dyspnea.
• Cardiac Ultrasound assesses LVEF and valvular function.
• Natriuretic Peptides (BNP, NT-proBNP) are used in testing.
  • HF unlikely: BNP < 35 pg/ml, NT-proBNP < 125 pg/ml
  • Suggestive of decompensated HF: BNP > 500 pg/ml
  • Limitations: Cannot differentiate between acute, acute-on-chronic, or chronic HF; also elevated in cor pulmonale and right ventricular dysfunction.
• D-dimer normal range: < 500 ng/ml
  • Age-adjusted value in patients over 50 years: Age x 10 μg/L
  • A raised level may be found in severe infections/sepsis, neoplasia, inflammatory diseases, aortic dissection, normal pregnancy, preeclampsia/eclampsia, stroke, acute ischemia with various locations, intracardiac thrombosis.
• Troponin: Elevated levels may occur in pulmonary embolism, myocarditis, stress cardiomyopathy, supraventricular arrhythmias, sepsis, hypoxia, hypoperfusion, stroke, subarachnoid hemorrhage, and kidney failure.
• Pulmonary CT is more sensitive than chest X-ray for detecting the cause of acute dyspnea.

Causes of Acute Dyspnea

• Respiratory issues include:
  • Upper and lower airways, lung parenchyma, and pleura
  • Examples: epiglottitis, angioedema, anaphylaxis, asthma, COPD exacerbation, airway obstruction, pneumonia, ARDS, pleural effusion, pneumothorax
• Cardiac issues include:
  • Heart and pericardium
  • Examples: decompensated heart failure, acute heart failure, acute coronary syndrome, acute severe MR or AR, myocarditis
• Pulmonary Circulation:
  • Pulmonary arteries and arterioles
  • Example: pulmonary embolism
• Other:
  • Chest wall and diaphragm disorders, blood abnormalities, metabolic issues, toxic substances, psychogenic factors

Common Causes in the ED

• Common causes include COPD, heart failure, pneumonia, acute myocardial infarction, supraventricular arrhythmia, malignant tumors, and pulmonary thromboembolism.

Specific Conditions and Treatments

• COPD Exacerbation:
  • Treatment includes oxygen therapy, non-invasive ventilation (CPAP, BIPAP), invasive mechanical ventilation, bronchodilators, corticosteroids, antibiotics and VTE prophylaxis.
• Acute Heart Failure/Pulmonary Edema:
  • Treatment includes oxygen, CPAP/BiPAP/invasive mechanical ventilation, IV loop diuretics and vasodilators.
• Asthma Exacerbation:
  • Treatment includes ICS-formoterol and SABA.
• ARDS (Adult Respiratory Distress Syndrome):
  • Characterized by acute respiratory failure with multiple causes, leading to acute lung injury and pulmonary edema.
  • Diagnosis involves assessing acute dyspnea, hypoxemia, polypnea, tachycardia, and bilateral pulmonary opacities.
  • Treatment is primarily supportive, including mechanical ventilation and management of underlying causes.
• Pulmonary Embolism (PE):
  • Diagnosis involves assessing risk factors and clinical probability.
  • Treatment depends on the risk level and may include anticoagulation, thrombolysis, or surgical embolectomy.