What is the best approach to manage a patient presenting with shortness of breath, potentially due to respiratory or cardiac causes, and with possible histories of asthma, COPD, or heart failure?

Management of Acute Shortness of Breath

Begin immediate oxygen therapy targeting 94-98% saturation for most patients, or 88-92% for those with COPD or risk of hypercapnic respiratory failure, while simultaneously assessing for life-threatening causes. 1

Immediate Assessment and Oxygen Delivery

Initial Oxygen Therapy Based on Saturation

• If SpO2 <85%: Start reservoir mask at 15 L/min immediately 1
• If SpO2 85-93%: Use nasal cannulae at 2-6 L/min or simple face mask at 5-10 L/min 1
• If COPD/hypercapnic risk present: Target 88-92% saturation pending blood gas results, then adjust to 94-98% if PCO2 is normal 1
• Measure respiratory rate and heart rate carefully—tachypnea and tachycardia are more common than visible cyanosis in hypoxemic patients 1

Critical Vital Signs to Obtain

• Respiratory rate (tachypnea indicates distress) 2
• Heart rate (tachycardia common in hypoxemia) 1
• Blood pressure (assess for shock or heart failure) 1
• Oxygen saturation (guide oxygen therapy) 1

Rapid Differential Diagnosis

Cardiac Causes

• Acute heart failure: Look for orthopnea, elevated jugular venous pressure, pulmonary edema on exam 3
  • BNP <100 pg/mL makes acute heart failure unlikely (LR- = 0.1) 1
  • BNP >500 pg/mL makes acute heart failure likely (LR+ = 6) 1
  • Consider CPAP or NIV for pulmonary edema 1
• Myocardial infarction: Most patients are not hypoxemic; avoid unnecessary high-concentration oxygen as it may increase infarct size 1
• "Cardiac asthma": Presents with wheezing and orthopnea from reflex bronchoconstriction due to pulmonary venous hypertension 1, 3

Pulmonary Causes

• Acute asthma: Administer inhaled short-acting beta-agonists (albuterol) for bronchodilation 1, 4
  • Assist with bronchodilator administration for patients with known asthma and acute shortness of breath 1
  • Use reservoir mask at 15 L/min if SpO2 <85% 1
• COPD exacerbation: Target oxygen saturation 88-92% to avoid hypercapnic respiratory failure 1
  • Recheck blood gases after 30-60 minutes 1
• Pneumonia: Use reservoir mask at 15 L/min if SpO2 <85%, otherwise nasal cannulae or simple face mask 1
• Pneumothorax: Requires aspiration or drainage if patient is hypoxemic 1
  • Most patients with pneumothorax are not hypoxemic and do not require oxygen 1
• Pulmonary embolism: Most patients with minor PE are not hypoxemic and do not require oxygen 1

When Standard Oxygen Therapy Is Insufficient

• Change to reservoir mask if desired saturation cannot be maintained with nasal cannulae or simple face mask 1
• Ensure senior medical staff assess the patient immediately 1
• Consider arterial blood gas measurement if clinical concern persists despite normal pulse oximetry 2

Specific Management Pitfalls

COPD Patients

• Do not over-oxygenate: Target 88-92% saturation initially to prevent hypercapnic respiratory failure 1
• Adjust to 94-98% only if PCO2 is normal on blood gas (unless history of previous hypercapnic respiratory failure requiring NIV) 1
• Beta-blockers are not contraindicated in COPD; cardio-selective agents reduce mortality by 31% 5

Asthma Patients

• Cardio-selective beta-blockers can be used if indicated for cardiac disease 5
• Beta-agonists are strongly associated with new heart failure (relative risk 3.41) and heart failure hospitalizations (odds ratio 1.74) 5
• Paradoxical bronchospasm can occur with albuterol—discontinue immediately if this develops 4

Heart Failure Patients

• Most patients with acute coronary syndromes are not hypoxemic 1
• Oxygen therapy may be harmful for non-hypoxemic patients 1
• Congestive heart failure can coexist with COPD in up to 20% of patients 5
• When both conditions coexist, hazard of death increases by 39% 5

Conditions That Do Not Require Oxygen

• Stroke: Most patients are not hypoxemic; oxygen may be harmful for non-hypoxemic patients with mild-moderate strokes 1
• Hyperventilation/panic attacks: Exclude organic illness first; rebreathing from paper bag may cause hypoxemia and is not recommended 1
• Severe anemia: Main issue is correcting anemia, not oxygen therapy 1

Specialist Referral Indications

• Refer to cardiologist or pulmonologist for cardiopulmonary testing when breathlessness with or without chest pain might be caused by heart disease or other conditions 1
• Consider psychological evaluation when hyperventilation and anxiety disorders are in the differential 1
• Perform spirometry and detailed pulmonary examination to determine if shortness of breath is associated with underlying conditions like COPD, obesity, skeletal defects, diaphragmatic paralysis, or interstitial fibrosis 1

Non-Pharmacological Symptomatic Management

• Hand-held fan directed at the face is first-line symptomatic treatment for breathlessness when oxygen saturation is normal 2
• Appropriately tailored exercise helps improve functional capacity in chronic breathlessness 1
• Breathing training, relaxation techniques, and psychological interventions can be tried 1