PULMONARY EMBOLISM DETECTION

Fatima Al Awadh

EMERGENCY INVESTIGATIONS

Pulse Oximetry

ElectroCardioGram.

Arterial Blood Gases.

Complete Blood Count.

Cardiac Enzymes.

Chest Radiograph.

PULSE OXIMETRY

detection and

ongoing monitoring

of hypoxaemia with

initiation of oxygen

supplementation as

necessary, while

undertaking

diagnostic work-up

for its cause.

ELECTROCARDIOGRAM

Acute coronary syndromes ST-T-segment changes.

Pericarditis, cardiac tamponade low voltage.

Pulmonary embolism tachycardia.

Right atrial enlargement p-wave changes

Change in the QRS right (COPD, pulmonary

hypertension) or left (hypertension, valvular heart

disease).

ARTERIAL BLOOD GASES

Hypercapnia exacerbation of COPD, stroke, or upper airway

obstruction.

Hypocapnia anxiety and hyperventilation, as in pulmonary

embolism.

Hypoxaemia ARDS, pneumonia, COPD, asthma, pulmonary

embolism, interstitial lung disease, stroke, or upper airway

obstruction.

Acidosis sepsis, pulmonary oedema, exacerbation of COPD

Alkalosis anxiety, dehydration, or pulmonary embolism.

COMPLETE BLOOD COUNT

Leukocytosis infectious process, autoimmune disease,

and leukemia.

Eosinophilia parasitic disease, certain vasculitides (e.g.,

Churg-Strauss syndrome), asthma, eosinophilic pneumonia, or

cocaine.

Anaemia the primary reason for dyspnoea

or may accompany it in drug-related lung

injury, acute chest syndrome of sickle cell disease, pulmonary

alveolar haemorrhage, or widespread infectious processes.

Thrombocytopenia viral infections, including influenza,

SARS, and Hantavirus pulmonary syndrome.

CARDIAC ENZYMES

Acute myocardial infarction

Myocarditis

Takotsubo cardiomyopathy

or Hypothyroidism.

Troponin I/T, Myoglobin, and CK-MB

CHEST RADIOGRAPH

Pulmonary venous congestion and an enlarged heart

CHF.

Parenchymal infiltrates infectious pneumonia, or

pulmonary oedema.

Pleural effusion CHF, liver failure, pulmonary embolism,

or pleuritis.

Lung hyperinflation COPD, exacerbation of asthma, or

foreign body aspiration.

Unilateral lucidity pneumothorax or a diaphragmatic

hernia.

Prominent hilar vessels pulmonary hypertension.

SPECIFIC INVESTIGATIONS FOR PE

CT angiography of the chest

D-DIMER

a by-product of intrinsic fibrinolysis.

elevated levels occur in the presence of a recent

thrombus.

not specific for venous thrombus.

absence of elevated levels suggests the absence

of recent thrombus because the test is sensitive.

V/Q SCANS

detect areas of lung that are ventilated but not perfused,

as occurs in PE

results are reported as low, intermediate, or high

probability of PE based on patterns of V/Q mismatch

completely normal scan excludes PE with nearly 100%

accuracy

Perfusion deficits may occur in many other lung

conditions, including pleural effusion, chest mass,

pulmonary hypertension, pneumonia, and COPD.

ABNORMAL PERFUSION SCAN

Showing multiple peripheral perfusion defects in both lungs. In the presence of a normal chest x

NORMAL VENTILATION SCAN

This "mismatch" between abnormal perfusion and normal

ventilation of the right lung indicates a high probability of acute

pulmonary embolism.

CT ANGIOGRAPHY OF THE CHEST

The best investigation for diagnosing and excluding pulmonary

embolism.

Fast, available, and noninvasive.

Also detect pulmonary parenchymal disease, pulmonary oedema,

airway and vascular abnormalities, pleural effusion.

The sensitivity is highest in lobar and segmental vessels and lowest

for emboli sub-segmental vessels and thus is less sensitive than

perfusion scans.

Sensitivities range from 53 to 100%; Specificities range from 81 to

100%.

REFERENCES

Merck Manuals.

Gyton Medical Physiology.

WALTER C. MORGAN, HEIDI L. HODGE, Diagnostic Evaluation of Dyspnea. Am

Fam Physician. 1998 Feb 15;57(4):711-716.

Conrad Wittram, Michael M. Maher, Albert J. Yoo, Mannudeep K. Kalra, , Jo-Anne

O. Shepard, and, Theresa C. McLoud, CT Angiography of Pulmonary Embolism:

Diagnostic Criteria and Causes of Misdiagnosis September 2004 Volume 24, Issue

5.

WWW.BestPractise.bmj.com

“Thank You”