PULMONARY EMBOLISM

PRESENTED BY,RESMI G S

INTRODUCTION

Problems of the vascular system includes disorders of the arteries and veins.

Peripheral arterial disease is a term used to describe a wide variety of conditions affecting arteries in the neck, abdomen and extremities.

Peripheral arterial disease can be subdivided into occlusive disease, aneurismal disease, and vasopastic phenomenon.

In contrast,venous diseases primarily affect the lower extremities and can be categorised into venous thrombosis and chronic venous insufficiency.

DEFINITION

• Pulmonary embolism is the blockage of pulmonary arteries by thrombus,fat or air emboli and tumour tissue.

• It is the most common complication in hospitalised patients.

• An embolus is a clot or plug that is carried by the bloodstream from its point of origin to a smaller blood vessel, where it obstructs circulation.

INCIDENCE

• Actual incidence of mortality and morbidity from pulmonary embolism is unknown, it is estimated that nearly 50,000 people die of pulmonary disease each year in the United states and another 650,000 have non fatal pulmonary embolism.

ETIOLOGY AND RISK FACTORS

• Virtually all pulmonary embolisms develop from thrombi(clots),most of which originate in the deep calf,femoral,popliteal,or iliac veins.

• Other sources of emboli include tumours, fat, air, bone marrow, amniotic fluid, septic thrombi, and vegetations on heart valves that develop with endocarditis.

• Major operations ,especially hip, knee, abdominal and extensive pelvic procedures predispose the client to thrombus formation because of reduced flow of blood through pelvis.

• Travelling in cramped quarters for a long time or sitting for long periods is also associated with stasis and clotting of blood.

• The most common sources of embolism are proximal leg deep venous thrombosis (DVTs) or pelvic vein thromboses.

• Any risk factor for DVT also increases the risk that the venous clot will dislodge and migrate to the lung circulation, which may happen in as many as 15% of all DVTs.

• The conditions are generally regarded as a continuum termed venous thromboembolism (VTE).

• The development of thrombosis is classically due to a group of causes named Virchow's triad (alterations in blood flow, factors in the vessel wall and factors affecting the properties of the blood).

• Often, more than one risk factor is present.

• Alterations in blood flow: immobilization (after surgery, injury, pregnancy (also procoagulant), obesity (also procoagulant), cancer (also procoagulant)

• Factors in the vessel wall: surgery, catheterizations causing direct injury ("endothelial injury")

• Factors affecting the properties of the blood (procoagulant state):– Estrogen-containing hormonal contraception– Genetic thrombophilia (factor V Leiden, prothrombin

mutation G20210A, protein C deficiency, protein S deficiency, antithrombindeficiency, hyperhomocysteinemia and  plasminogen/fibrinolysis disorders)

– Acquired thrombophilia (antiphospholipid syndrome, nephrotic syndrome, paroxysmal nocturnal hemoglobinuria)

– Cancer (due to secretion of pro-coagulants)

CLINICAL FEATURES

• Severity of clinical manifestations of pulmonary embolism depends on the size of the emboli and the size and number of blood vessels occluded.Most common manifestations are,

Anxiety Sudden onset of unexplained dyspnea Tachypnea or tachycardia Cough Pleuritic chest pain Hemoptysis Crackles

FeverAccentuation of the pulmonic heart soundSudden change in mental status as a result of hypoxemia

•In massive emboli,ShockPallorSevere dyspneaCrushing chest painPulse is rapid and weakBp is lowECG indicates right ventricular strain

•In medium sized emboli,Pleuritic chest painDyspnea Slight feverProductive cough with blood streaked sputum

•In small emboli,Pulmonary hypertensionECG and chest X-ray indicates right ventricular hypertrophy

PATHOPHYSIOLOGY

• When emboli travel to the lungs, they lodge in the pulmonary vasculature .

• The size and number of emboli determine the location.

• Blood flow is obstructed ,leading to decreased perfusion of the section of the lung supplied by the vessel.

• The client continues to ventilate the lung portion ,but because the tissue is not perfused, resulting in hypoxemia.

•If an embolus lodges in a large pulmonary vessel, it increases proximal pulmonary vascular resistance, causes atelectasis, and eventually reduces cardiac output.•If the embolus is in a smaller vessel, less dramatic clinical manifestations follow but perfusion is still altered.•The arterioles constrict because of platelet degranulation, accompanied by a release of histamine, serotonin, catecholamines and prostaglandins.•These hemical agents result in bronchial and pulmonary artery constriction.•This vasoconstriction probably plays a major role in the hemodynamic instability that follows pulmonary embolism.

•Pulmonary embolism can lead to right sided heart failure.•Once the clot lodges, affected blood vessels in the lung collapse.•This collapse increases the pressure in the pulmonary vasculature.•The increased pressure increases the work load of the right side of the heart, leading to failure.•Massive pulmonary embolism of the pulmonary artery can also result in cardiopulmonary collapse from lack of perfusion and resulting hypoxia and acidosis.

DIAGNOSTIC STUDIES

History and physical examination Venous studies Chest X-ray Continous ECG monitoring ABGs CBC count with WBC differential D –dimer level Lung scan(ventilation and perfusion) Pulmonary angiography Spiral CT scan

MEDICAL MANAGEMENT

• The objectives of treatment are, Prevent further growth or multiplication of thrombi in

the lower extremities Prevent embolization from the upper or lower

extremities to the pulmonary vascular system. Provide cardiopulmonary support if indicated.

CONSERVATIVE THERAPY

• The administration of O2 by mask or cannula may be adequate for some patients.O2 is given in a concentration determined by ABG analysis.

• In some situations,endotracheal intubation and mechanical ventilation may be needed to maintain adequate oxygenation.

• Respiratory measures such as turning, coughing and deep breathing are necessary to prevent or treat atelectasis.

•If shock is present, vasopressor agents may be necessary to support systemic circulation .If heart failure is present, digitalis and diuretics are used.•Pain resulting from pleural irritation or reduced coronary blood flow is treated with narcotics, usually morphine.

DRUG THERAPY

• Anticoagulant therapy-Properly managed anticoagulant therapy is effective in the treatment of many patients with pulmonary embolism.

• Heparin and Warfarin are the anticoagulant drugs of choice.

• Unless contraindicated, heparin should be started immediately and is continued while oral anticoagulants are initiated.

• The dosage of heparin is adjusted according to PTT and warfarin dose is determined by International normalized ratio.

•Fibrinolytic therapy-The effectiveness of fibrinolytic therapy in the management of a massive pulmonary embolism is not clear,but it may be useful in clients who are hemodynamically unstable.•Thrombolytic agents lyse the clots and restore right-sided heart function.

SURGICAL MANAGEMENT

• Surgical interventions that may be used in the treatment of pulmonary embolism include,

Vena caval interruption with the insertion of a filter and

Pulmonary embolectomy• The Greenfield filter, a basket like cone of

wires bent to look like an umbrella ,is the most commonly used filter.

•The filter is inserted by threading it up the veins in the leg or neck until it reaches the venacava at the level of renal arteries.•The filter allows blood flow while trapping emboli, however venacava filters are less effective than coagulation and may lead to deep vein thrombosis and so these are generally are used only when anticoagulants are contraindicated or ineffective.

•Embolectomy is used in clients with significant hemodynamic instability caused by the embolus,especially those with unstable circulation and contraindications to thrombolytic therapy.•An embolectomy involves surgical removal of emboli from the pulmonary arteries by either thoracotomy or an embolectomy catheter.

CONCLUSION

• Lower airway disorders include asthma, chronic air flow limitations and inflammations of the airways.

• Nursing care centers on reversal of any airway spasm and education of the client about how to live with the disorder and how to reduce the risk of future problems.

• Pulmonary embolism is a potentially life threatening disorder that usually can be managed effectively with prompt recognition.