Chest pain following long haul flight (547/1700)

A 50yo woman returned by air to the UK from Australia. 3days later she presented with sharp
chest pain and breathlessness. Her CXR and ECG are normal. What is the single most
appropriate inv?
a. Bronchoscopy
b. Cardiac enzymes
c. CT
d. MRI
e. Pulse oximetry
f. V/Q scan
g. CTPA








































answer: G
CXR and ECG do not rule out pulmonary embolism, recent history of long air journey is very suggestive of PE

Pulmonary Angiogram (Gold Standard)

Filling defect indicative of embolus; negative angiogram excludes clinically relevant PE

More invasive, and harder to perform than CT, therefore done infrequently

D-Dimer

Highly sensitive D-dimer result can exclude DVT/PE if pretest probability is already low, little value if pretest probability is high

If D-dimer positive, will need further evaluation with compression U/S

CT Angiogram Both sensitive and specific for PE

Diagnosis and management uncertain for small filling defects

CT may identify an alternative diagnosis if PE is not present

CT scanning of the proximal leg and pelvic veins can be done at the same time and may be helpful

Venous Duplex U/S or Doppler

With leg symptoms

Positive test rules in proximal DVT

Negative test rules out proximal DVT

Without leg symptoms

Positive test rules in proximal DVT

Negative test does not rule out a DVT: patient may have non-occlusive or calf DVT

ECG

Findings not sensitive or specific

Sinus tachycardia most common; may see non-specific ST segment and T wave changes

RV strain, RAD, RBBB, S1-Q3-T3 with massive embolization

CXR

Frequently normal; no specific features

Atelectasis (subsegmental), elevation of a hemidiaphragm

Pleural effusion: usually small

Hampton’s hump: cone-shaped area of peripheral opacification representing infarction

Westermark’s sign: dilated proximal pulmonary artery with distal oligemia/decreased vascular markings (difficult to assess without prior films)

Dilatation of proximal PA: rare

V/Q Scan Very sensitive but low specificity

Order scan if

CXR normal, no COPD

Contraindication to CT (contrast allergy, renal dysfunction, pregnancy)

Avoid V/Q scan if

CXR abnormal or COPD

Inpatient

Suspect massive PE

Results

Normal: excludes the diagnosis of PE

High probability: most likely means PE present, unless pre-test probability is low

60% of V/Q scans are nondiagnostic

Echocardiogram

Useful to assess massive or chronic PE

Not routinely done

ABG

No diagnostic use in PE (insensitive and nonspecific)

May show respiratory alkalosis (due to hyperventilation)