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Seminar

Pulmonary Embolism

DVT – Epidemiology and Etiology :
-Annual incidence of venous thromboembolism (VTE) is 1/1000
-DVT accounts for over one half of VTE
-Carefully evaluated, up to 80% of patients with VTE have one
or more risk factors
-Majority of lower extremity DVT arise from calf veins but ~20%
begin in proximal veins
-About 20% of calf-limited DVTs will propagate proximally
DVT – VTE Risk Factors

Malignancy

-Surgery
-Trauma
-Pregnancy
-Oral contraceptives or hormonal therapy
-Immobilization
-Inherited thrombophillia
-Presence of venous catheter
-Congestive failure
-Antiphospholipid antibody syndrome
-Hyperviscosity
-Nephrotic syndrome
-Inflammatory bowel disease

An Introduction to Pulmonary embolus
-Pulmonary embolism is a life-threatening condition that occurs
when a clot of blood or other material blocks an artery in the
lungs.
-This is an extremely common and highly lethal condition that is
a leading cause of death in all age groups.
-One of the most prevalent disease processes responsible for
in-patient mortality (30%)
-Overlooked diagnosis.

Pulmonary Embolism back ground



Prompt diagnosis and treatment can dramatically reduce the

mortality and morbidity rate.



Majority of the cases are unrecognised clinically.



One third of the patients who survive an initial PE die of a

future embolic episode.



Many patients who die of PE have

not had any diagnostic workup nor have they received any
prophylaxis for the disease
.



In most cases the CLINICIANS have not even considered the

diagnosis of PE.
Pathophysiology of pulmonary embolism



It is often a fatal complication of underlying venous

thrombosis
.



Normally microthrombi (RBC,Platelets and Fibrin) are

formed and lysed with in the venous circulatory system.



Under pathological condition these microthrombi may

escape and propagate and will block the pulmonary blood
vessels causing PE
Predisposing factors



Patients on prolonged bed rest for > a week. Prolonged

immobilization.



Patients in ICU, CCU.



After bypass surgery or any surgery.



All trimesters of pregnancy and puerperium.



Older patients – Age no bar still.

Predisposing factors

: 1-CCF. 2-Fractures. 3-Oral

Contraceptives. 4-Drug abuse. 5-MI. 6-Obesity. 7-Old age. 8-
Malignancy. 9-Catheter

Patient presentation



Haemoptysis, Dyspnoea and Chest pain –

o (Virchows Triad)



Back pain, Abdominal pain, wheezing, SOB, Seizures,

Productive cough, Hiccoughs, Fever……



Can be asymptomatic

Diagnostic Modalities in PE



ECG***



D Dimer assay test



Plain film radiography



Radionuclide imaging (VQ Scan)



CT Angiography



Pulmonary angiography



Echocardiography Ultrasound(DVT)***



MRI & MRA0

-Dimer Assays



Gainfully employed to select patients for further

radiological imaging.



It is a cross linked fibrin degradation product and a

plasma marker of fibrin lysis.



Serum level less than 500ng/L excludes PE with 90-95%

accuracy.



Unfortunately a positive test is non specific (specificity

only 25 – 67% and occurs in about 40 – 69% of the patients

Embolism without Infarction



Most PEs (90%)



Frequently normal chest x-ray



Pleural effusion



Westermark’s sign



“Knuckle” sign abrupt tapering of an occluded vessel

distally



Elevated hemidiaphragm

Ventilation

-perfusion scanning V/Q Scanning



Single most important diagnostic modality for detecting

PE.



Always indicated when PE is suspected and there is no

other diagnosis.



1 in every 25 pts sent home after a normal V/Q scan

actually has a PE that has been

MISSED

Ventilation

-perfusion scanning V/Q Scanning



Radiological procedure which is often used to confirm or

exclude the diagnosis of pulmonary embolism. It may also
be used to monitor treatment.



The ventilation part of the scan is the inhalation of

Krypton 81m, which has a short half life and is a pure
gamma emitter. Ventilation is assessed under a gamma
camera.

Ventilation

perfusion scanning V/Q Scanning



The perfusion part of the scan is achieved by injecting the

patient with technetium 99m, which is coupled with macro
aggregated albumin (MAA). This molecule has a diameter
of 30 to 50 micrometres, and thus sticks in the pulmonary
capillaries.



An embolus shows up as a cold area when the patient is

placed under a gamma camera. The MAA has a half life of
about 10 hours

Spiral CT



HRCT (spiral) CT with CT angiography is a promising

technique.



CT unlikely to miss any lesion.



CT has better sensitivity, specificity and can be used

directly to screen for PE.



CT can be used to follow up “non diagnostic V/Q scans.

Pulmonary Angiogram



Positive angiogram provides 100% certainty that an

obstruction exists in the pulmonary artery.



Negative angiogram provides > 90% certainty in the

exclusion of PE.



Catherterisation of the

Subclavian vein

–

Superior vena

cava

–

right atrium

–

right ventricle

–

main pulmonary artery

Treatment of pulmonary embolism



Emergency treatment and hospitalization are necessary.

In cases of severe, life-threatening pulmonary embolism,
definitive treatment consists of dissolving the clot with
thrombolytic therapy. Anticoagulant therapy prevents the
formation of more clots and allows the body to re-absorb
the existing clots faster.



Thrombolytic therapy (clot-dissolving medication)

includes streptokinase, urokinase, or t-PA.



Anticoagulation therapy (clot-preventing medication)

consists of heparin by

intravenous

infusion initially, then

oral warfarin (Coumadin).

Subcutaneous

low-molecular

weight heparin is often substituted for intravenous heparin
in many circumstances

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