Shortness of Breath OSCE - Pulmonary Embolism

Case Overview

• Age/Sex: 35-year-old female
• Occupation: Primary school teacher
• Setting: Emergency department / urgent assessment clinic
• Chief complaint: "Shortness of breath"

Patient Script

Who I Am

I'm 35, I teach primary school, and I had a knee operation two weeks ago.

What Brings Me In

I've been feeling short of breath for a few days and it's getting worse when I walk up the stairs.

My Story

About 5 days ago I started getting a bit more breathless than usual — at first when I hurried or climbed a couple of flights of stairs, but it's become more noticeable over the last 48 hours. I also had a brief, sharp discomfort when I took a deep breath yesterday, like a mild pleuritic chest twinge, but it wasn't a crushing pain. I had my knee arthroscopy 2 weeks ago and was taking it easy for the first week. I thought it might be a chest infection at first because I had a cough for one day a week ago, but the cough went away. I sometimes get palpitations when I'm anxious.

I also noticed my left calf felt a bit tight and slightly swollen compared to the other leg since the operation, but I put that down to the surgery and being less active. I haven't vomited or passed any blood. I didn't faint.

My Medical Background

• Past medical history: mild childhood asthma (no inhalers used for years), no previous blood clots
• Recent surgery: left knee arthroscopy 14 days ago (day surgery, discharged same day)
• Medications: combined oral contraceptive pill (ethinylestradiol + levonorgestrel), paracetamol PRN for knee
• Allergies: none known
• Social: smokes ~5 cigarettes/day, drinks alcohol occasionally, lives with partner
• Family history: grandmother had a stroke in her 70s

What I Think & Worry About

• I worry this might be a chest infection or that my heart is acting up.
• I wonder if I'm having an anxiety attack — I’ve had panic before and the palpitations worry me.
• I want to know if this is something serious that needs treatment now.

If You Ask Me About Other Symptoms...

• Chest pain: "Only a brief sharp twinge when I took a big breath yesterday, nothing constant."
• Cough: "Had a little cough for a day last week, then it went away."
• Fever: "Felt a bit feverish once but I don't have a high temperature now."
• Leg symptoms: "Left calf has felt a bit tight and looks slightly bigger than the right, but it doesn't hurt much — I thought it was from the surgery."
• Dizziness/syncope: "No fainting. I felt a bit lightheaded once when I stood up quickly."
• Recent travel: "I drove a long distance (about 4 hours) to visit family 10 days ago after the surgery." (red herring / potential risk)
• Anxiety history: "I had a panic attack once in my twenties, so I know what that feels like, but this is different."

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Clinical Summary

Examination

• General: alert, anxious-appearing, speaking in sentences, not in acute respiratory distress
• Vitals: temperature 37.8°C, heart rate 110 bpm (regular), blood pressure 118/76 mmHg, respiratory rate 22/min, SpO2 93% on room air
• Cardiovascular: normal heart sounds, no murmurs, no raised JVP
• Respiratory: chest clear to auscultation bilaterally, no wheeze, no focal crackles
• Extremities: left calf circumference ~1.5 cm larger than right, mild tenderness on deep calf palpation, no overt erythema
• Neurological: grossly normal, no focal deficit

Investigations

• ECG: sinus tachycardia 110 bpm; no ST elevation, no new ischaemic changes
• CXR: clear, no consolidation, no pneumothorax
• Pulse oximetry: SpO2 93% on room air
• ABG (room air): pO2 ~8.5 kPa (approx 64 mmHg), pCO2 normal, mild hypoxaemia
• D-dimer: 1,200 ng/mL (elevated; reference <500 ng/mL)
• Lower limb duplex ultrasound: non-occlusive thrombus in left popliteal vein (if performed)
• CTPA: filling defect in a segmental branch of the right lower lobe pulmonary artery (consistent with pulmonary embolus)

Diagnosis

Primary: Acute pulmonary embolism

• Evidence: recent surgery (2 weeks), ongoing exertional dyspnea and mild pleuritic chest pain, tachycardia and hypoxaemia, elevated D-dimer, imaging (CTPA) demonstrating a filling defect.

Differential diagnoses and reasoning:

• Community-acquired pneumonia: less likely given clear CXR, only transient cough, low-grade fever only once
• Anxiety/panic attack: may explain palpitations and breathlessness but does not explain hypoxaemia, elevated D-dimer, or calf swelling
• Asthma exacerbation: unlikely—no wheeze, no recent use of inhalers, and focal D-dimer/CT abnormalities not explained by asthma
• Musculoskeletal chest wall pain: possible for sharp localized pain, but does not account for hypoxaemia and imaging findings

Management

• Initial stabilization: give supplemental oxygen to maintain SpO2 ≥94% (patient currently 93% — provide oxygen as needed)
• Anticoagulation: start therapeutic low-molecular-weight heparin (e.g., enoxaparin) immediately unless contraindicated; consider switching to an oral direct anticoagulant for outpatient continuation once stable
• Risk assessment: assess haemodynamic stability (this patient is normotensive) — no thrombolysis indicated
• Investigations/precautions: pregnancy test prior to initiating long-term DOAC in a woman of childbearing potential if switching from LMWH
• Source control: arrange lower limb duplex ultrasound to assess for DVT if not yet done
• Stop contributing factors: advise immediate discontinuation of combined oral contraceptive pill
• Further planning: assess need for inpatient observation (likely short admission), discuss anticoagulation duration (at least 3 months given provoked by recent surgery and ongoing risk factors), consider thrombophilia testing only if unprovoked or recurrent
• Patient education: explain diagnosis, signs of bleeding on anticoagulation, advice on mobilization and smoking cessation

Key Learning Points

• Consider pulmonary embolism in any patient with unexplained dyspnea and recent surgery, even if presentation is atypical and chest examination/CXR are unremarkable.
• Use objective testing (Wells score/D-dimer and imaging) rather than relying on presence of classic symptoms; an elevated D-dimer and hypoxaemia should prompt imaging when clinical suspicion exists.
• Identify and address reversible risk factors (e.g., stop combined oral contraceptive) and initiate prompt anticoagulation in confirmed PE unless contraindicated.