Dyspnea and Respiratory Distress

On this page

Dyspnea: Definition & Pathophysiology - Breathless Beginnings

  • Dyspnea: Subjective awareness of uncomfortable breathing.
  • Types:
    • Acute: <2-4 weeks; Chronic: >2-4 weeks.
    • Orthopnea: Dyspnea supine.
    • PND (Paroxysmal Nocturnal Dyspnea): Sudden nocturnal dyspnea.
    • Trepopnea: Dyspnea in one lateral decubitus position.
  • Pathophysiology:
    • Respiratory center stimulation.
    • Inputs from:
      • Chemoreceptors: Central (medullary; $CO_2$, $H^+$); Peripheral (carotid/aortic bodies; $O_2$, $CO_2$, $H^+$).
      • Mechanoreceptors: Lung (stretch, J-receptors); Chest wall (proprioceptors).
    • Ventilation/Perfusion (V/Q) mismatch.

Dyspnea pathophysiology diagram

⭐ Orthopnea is a hallmark of left ventricular failure but can also occur in severe diaphragmatic weakness.

Dyspnea: Etiology - The Usual Suspects

Major Causes:

  • Pulmonary: COPD, Asthma, Pneumonia, PE, Pneumothorax, ILD, Pleural effusion
  • Cardiac: CHF, ACS, Arrhythmias, Pericardial (tamponade, constrictive), Valvular
  • Neuromuscular: Myasthenia, GBS, Diaphragm paralysis
  • Hematologic: Severe Anemia
  • Metabolic: Acidosis (DKA - Kussmaul)
  • Psychogenic: Anxiety, Panic

📌 Acute Dyspnea (4P+A+C):

  • Pneumothorax
  • Pulmonary Embolism (PE)
  • Pneumonia
  • Pulmonary Edema (APO)
  • Asthma
  • Cardiac (ACS/Arrhythmia)

Differentiating Acute Causes:

FeaturePEPneumothoraxAPOAsthma
OnsetSuddenSuddenSudden/RapidGradual/Sudden
Chest PainPleuriticPleuritic, ipsi.+/- PressureTightness
Breath SoundsNormal/Crackles/Rub↓/Absent ipsi.Bilat. crackles/wheezesBilat. wheezes
CXRNormal/Hampton's/WestermarkPleural lineBilat. infiltrates/Kerley BHyperinflation/Normal
Key Assoc.DVT riskTall, thin; traumaHeart disease HxAsthma Hx, triggers

Dyspnea: Clinical Evaluation - Unmasking Dyspnea

  • History: Onset (sudden/gradual), duration, mMRC severity, character, aggravating/relieving factors. Associated: chest pain, cough, fever, wheeze, hemoptysis. PMH, meds, smoking.
  • Physical Exam:
    • General: Distress, cyanosis, accessory muscle use.
    • Vitals: RR, SpO2 (< 90% critical), HR, BP.
    • Respiratory: Palpation, percussion, auscultation (wheezes, crackles, rubs, ↓ breath sounds).
    • Cardiac: JVP, S3, murmurs, edema.
    • Signs of DVT.
  • Initial Investigations: Pulse oximetry, CXR, ECG, ABG ($P(A-a)O_2$).
  • Further: CBC, D-dimer, BNP/NT-proBNP, Troponins, Spirometry/PFTs, Echo, CT chest (CTPA, HRCT).

CXR showing bilateral pleural effusion and consolidation

⭐ Pulsus paradoxus >10 mmHg is a key finding in cardiac tamponade and severe asthma/COPD.

Dyspnea: Management Principles - Breathing Easier

  • General Approach: ABCDE (Airway, Breathing, Circulation, Disability, Exposure). Secure airway, administer Oxygen.
    • Target SpO2: 94-98% (general); 88-92% in COPD with hypercapnic failure.
  • Non-Invasive Ventilation (NIV - CPAP/BiPAP):

    • Indications: COPD exacerbation (respiratory acidosis), cardiogenic pulmonary edema.
    • Contraindications: Facial trauma, undrained pneumothorax, hemodynamic instability, GCS < 8.
  • Life-Threatening Causes: Quick Management

    • Acute Pulmonary Edema: Diuretics, Nitrates, NIV. 📌 LMNOP (Lasix, Morphine, Nitrates, Oxygen, Position).
    • Acute Severe Asthma/COPD: Bronchodilators (SABA, SAMA), Corticosteroids, O2. Consider MgSO4 for asthma.
    • Tension Pneumothorax: Immediate needle decompression → chest tube.
    • Massive Pulmonary Embolism: Anticoagulation; Thrombolysis/embolectomy if unstable.

Tension Pneumothorax Signs and Symptoms

⭐ In tension pneumothorax, needle thoracostomy should be performed in the 2nd intercostal space, mid-clavicular line, or the 5th intercostal space, anterior axillary line, over the superior border of the rib below to avoid neurovascular bundle.

High‑Yield Points - ⚡ Biggest Takeaways

  • Key acute dyspnea causes: PE, pneumothorax, ACS, asthma/COPD exacerbation.
  • Key chronic dyspnea causes: COPD, heart failure, ILD, anemia.
  • Orthopnea & PND: hallmarks of left ventricular failure (LVF).
  • Platypnea-orthodeoxia: linked to hepatopulmonary syndrome, R-L shunts.
  • Kussmaul's respiration: signifies severe metabolic acidosis (e.g., DKA).
  • Pulsus paradoxus >10 mmHg: points to cardiac tamponade, severe asthma/COPD.
  • Acute respiratory distress immediate management: prioritize ABC (Airway, Breathing, Circulation) and administer supplemental oxygen.

Practice Questions: Dyspnea and Respiratory Distress

Test your understanding with these related questions

In a patient with COPD, what is the best management option?

1 of 5

Flashcards: Dyspnea and Respiratory Distress

1/10

If the PSA is found elevated (in a hard feeling prostate) and cancer is suspected, the next step would be to do a _____ followed by biopsy

TAP TO REVEAL ANSWER

If the PSA is found elevated (in a hard feeling prostate) and cancer is suspected, the next step would be to do a _____ followed by biopsy

MRI

browseSpaceflip

Enjoying this lesson?

Get full access to all lessons, practice questions, and more.

Start Your Free Trial