Author: akil, Posted on Monday, September 06 @ 08:23:07 IST by RxPG  

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WHAT THEY MEAN WHEN THEY SAY PULMONARY MICROEMBOLISM IS PULMONARY TUMOUR MICROEMBOLISM.........

the gold standard for the diagnosis of pulmonary microembolism is
1)lung biopsy
OR
2)video assisted thoracoscopic surgery


When the patient is too hypoxemic to be subjected to lung biopsy then pulmonary wedge aspiration cytology or other modalities may be tried!

laboratory analysis
blood gas analysis reveals hypoxemia and respiratory alkalosis

angiography
the role of angiography is to exclcude the venous thromboembolic disease. In microembolism the sites of microembolism are confined to the capillary bed and arterioles which are BEYOND THE RESOLUTION LIMITS OF CONVENTIONAL ANGIOGRAPHY …

even CT angiography does not have the resolution limit to detect microembolism..findings of beaded and dilated peripheral pulmonary arteries on CT scan suggest micro embolism and this should not b confused with beaded septa( produced by the thickening of peribronchovascular interstitium and fissures) seen in lymphangitic carcinomatosis(but these lymhangitic carcinamatosis are thought to arise from tumour micrembolism though)

ventilation perfusion radionuclide imaging
normal results may be seen in ventilation scan but when perfusion scan is donenumerous small defects outlining the pulmonary fissures and broncho pulmonary segments.This is called segmented contour pattern (not unique …seen in pulmonary vasculitis, fat or oil embolism and primary puilmonary hypertension)

Rt heart catheterization
High rt ventricular systolic pressure of 50- 60 mm Hg
Mean pulmonary arterial pressure- 50 – 100 mm Hg
Pulmonary wedge pressure is normal

pulmonary wedge aspiration cytology
pulmonary microvascular cytology(PMVC) can be obtained by placing the pulmonary art in wedge position and slowly aspirating blood from the pulmonary arterial port..first 10 to 13 ml of blood is discarded and then 5 to 10 ml of blood is drawn into heparin treated tube for cytologic analysis!metastatic cells are seen.

False positive were seen in extensive pulmonary infarction and also in extensive tumour of hepatic veins!