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A 68-year-old man presents with severe shortness of breath and cyanosis. Arterial blood gas analysis shows a low PaO₂ with a normal or low PaCO₂. DIAGNOSIS SUB-QUESTIONS A. What is the diagnosis? B. What are the causes of pleuritic chest pain? C. What are the clinical signs? D. What is the management?

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"pulmonary embolism"[MeSH Terms] AND management

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2026 pulmonary embolism diagnosis management guideline ESC ACCP

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https://www.acc.org/about-acc/press-releases/2026/02/19/19/2…

A. Diagnosis

Acute pulmonary thromboembolism (pulmonary embolism, PE), likely a high-risk or massive PE if severe dyspnea, cyanosis, hypotension, shock, syncope, or right-heart strain is present.
The ABG pattern of hypoxemia with normal or low PaCO₂ reflects ventilation-perfusion mismatch with reflex hyperventilation. It supports PE but is not diagnostic. In PE, emboli usually originate from deep veins of the legs or pelvis and lodge in pulmonary arteries. Gray's Anatomy for Students, p. 281.

B. Causes of pleuritic chest pain

Pleuritic pain is sharp pain made worse by inspiration, coughing, or movement. Major causes include:
  • Pulmonary embolism with pulmonary infarction
  • Pneumothorax
  • Pneumonia with pleurisy
  • Viral pleuritis
  • Tuberculosis
  • Pleural effusion or empyema
  • Pericarditis
  • Malignancy involving pleura
  • Rib fracture, chest-wall trauma, costochondritis
  • Autoimmune pleuritis, for example SLE or rheumatoid disease
  • Aortic dissection and esophageal rupture, which are dangerous alternative diagnoses

C. Clinical signs of pulmonary embolism

Common findings are nonspecific:
  • Sudden-onset dyspnea
  • Tachypnea
  • Tachycardia
  • Hypoxemia and cyanosis
  • Pleuritic chest pain, sometimes hemoptysis if pulmonary infarction occurs
  • Cough, anxiety, sweating, syncope, or presyncope
  • Low-grade fever may occur
  • Signs of DVT: unilateral calf/thigh swelling, pain, warmth, erythema, or dilated superficial veins
  • Chest examination may be normal, or may reveal pleural rub or basal crackles
Features of severe PE / acute right-ventricular failure:
  • Hypotension or shock
  • Raised JVP
  • Loud P2, right ventricular heave
  • New right-sided S3
  • Syncope, altered consciousness, oliguria, cardiac arrest
  • ECG may show sinus tachycardia, right-heart strain, or rarely S1Q3T3 pattern

D. Management

This is an emergency. Start stabilization and diagnostic assessment simultaneously.

1. Immediate measures

  • ABC approach and continuous cardiac, BP, SpO₂ monitoring.
  • Give supplemental oxygen for hypoxemia.
  • Obtain IV access, ECG, chest radiograph, ABG, CBC, renal function, coagulation profile, troponin, BNP, and group/cross-match if unstable.
  • Avoid excessive IV fluids, as they can worsen right-ventricular failure. If shock is present, use cautious fluids and a vasopressor such as norepinephrine in a monitored critical-care setting.
  • Treat cardiac arrest according to ALS protocols while considering PE as a reversible cause.

2. Confirm or exclude PE

  • Assess pretest probability, for example Wells score.
  • In low/intermediate probability cases, use age-adjusted D-dimer where appropriate.
  • CT pulmonary angiography (CTPA) is the usual confirmatory test.
  • Use V/Q scanning if CTPA is contraindicated or unsuitable.
  • Compression ultrasonography of leg veins can establish DVT and may support treatment when definitive chest imaging is not feasible.
  • In unstable patients, bedside echocardiography may show acute right-ventricular dilatation/strain and help support immediate decisions.

3. Anticoagulation

If clinical probability is high and bleeding risk is acceptable, start anticoagulation while diagnostic imaging is being arranged.
  • Hemodynamically stable PE: LMWH, fondaparinux, or an appropriate direct oral anticoagulant.
  • Unstable PE, anticipated thrombolysis, severe renal impairment, or likely procedure: IV unfractionated heparin is often preferred because it can be stopped and reversed rapidly.
  • For most confirmed acute PE patients, anticoagulation is the main treatment. Current US guidance generally prefers DOACs over warfarin for eligible nonpregnant patients, as summarized by the 2026 AHA/ACC acute PE guideline.

4. Reperfusion therapy for high-risk PE

For PE with persistent hypotension or shock, give systemic thrombolysis unless contraindicated, commonly alteplase.
If thrombolysis is contraindicated or unsuccessful:
  • Catheter-directed thrombolysis or mechanical thrombectomy
  • Surgical pulmonary embolectomy, where expertise is available
  • Mechanical circulatory support in refractory collapse in specialist centers

5. Duration and prevention

  • Anticoagulate for at least 3 months.
  • Continue longer if PE is unprovoked, recurrent, associated with persistent risk factors, or cancer-related, balanced against bleeding risk.
  • Identify provoking factors: recent immobility, surgery, trauma, malignancy, previous VTE, thrombophilia, and medications.
  • An IVC filter is reserved for patients with an absolute contraindication to anticoagulation or recurrent PE despite adequate anticoagulation.
Severe breathlessness and cyanosis with suspected PE require immediate emergency or critical-care assessment, not outpatient management.
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