Pulmonary embolism: therapy and diagnostics

Diagnosis of pulmonary embolism

It is not easy to diagnose a pulmonary embolism, because the symptoms are very general.

The first thing the doctor needs to do is a targeted examination and then some further examinations.

Laboratory testing

1. The blood test can help detect if a person is prone to conditions such as deep vein thrombosis or pulmonary embolism, even if no clots can be detected with it.
2. The most important value in the blood test is the D-dimer, a fibrin degradation product.
3. When a blood clot forms, the plasmid breaks up the fibrin structure and then creates the D-dimer.
4. In 90% of cases of pulmonary embolism, values > 500 ng/ml result.
5. If the value is normal, you can be sure that there is no deep vein thrombosis, but the positive case does not necessarily mean the opposite.
6. Troponin: is very sensitive and specific to myocardial damage (acute myocardial infarction, heart failure, acute pericarditis, myocarditis, hypertensive heart disease). Elevated troponin levels may also be related to pulmonary embolism caused by an abnormality of the right ventricle.
7. Blood gas analysis (BGA) is an examination used to determine the partial pressure of oxygen and carbon dioxide in the blood. This examination is not very meaningful for this disease, because there are other disorders that can change these values.
8. In most cases, patients with pulmonary embolism also have hypocapnia (low CO₂concentration in the blood).

Apparative investigations for pictorial representation

1) Radiography (chest X-ray) does not show coagel, but allows to rule out other diseases such as pneumonia, pneumothorax, pulmonary edema and lung tumor.

2) Angiography, for this examination, a contrast fluid is used, which makes it possible to see the embolus directly and to exclude other lung diseases, such as pleural effusion. Most patients experience multiple embolisms.

3) Pulmonary angiography: until 2003, it was considered the gold standard in the diagnosis of pulmonary embolism, and in fact this method is the most sensitive and very specific (negative cases occur only 1%).
The doctor injects a contrast agent and can see if there is a complete occlusion of a vessel or a lack of filling of vessels. In addition, one recognizes indirect signs, such as slowing or reducing the flow and delaying the venous outflow. A major advantage is the possibility of performing local fibrin-relieving therapy via an angiography catheter.

However, this is an invasive examination in which the catheter is passed through the heart valves. The greatest complications are arrhythmias, cardiac perfusions, acute renal failure and respiratory failure. Today, spiral CT is an excellent alternative.

4) CT angiography of the thorax: the spiral technique allows continuous rapid scanning of an entire organ with a sensitivity of 95.5% and a specificity of 97.6%. It became the most widely used second-level investigation. If the examination is negative, this excludes the possibility of a significant embolism in the following 6 months, so that anticoagulant therapy can be avoided. Some advantages are:

• fast execution,
• possible exclusion of infarction,
• less invasive and with fewer complications than pulmonary angiography.

The CT scan (figure below) shows in the area of the white-colored blood vessels:

• gray spots, if the artery is partially occluded,
• black spots when the artery is completely occluded.

5) Lung MRI: used in individual cases (for example, if there are absolute contraindications to a spiral CT).

6) Color Doppler sonography is used to control blood flow in the leg veins and identify blood clots in the lungs.

7) The electrocardiogram (ECG) is useful in pulmonary embolism because it can indicate hypertrophy of the right ventricle.

In 70% of cases, it is abnormal, but not specific to an embolism. It must therefore be compared with another previous investigation. The following may occur:

• sinus tachycardia,
• abnormal heart rhythm (extrasystoles, atrial fibrillation),
• Right heart stress signs.

8) Echocardiogram: any patient suspected of having a pulmonary embolism must undergo an emergency echocardiographic examination. This method has shown a sensitivity of 87% and a specificity of 100%.

The examination may indicate that:

1. direct signs of pulmonary embolism, such as visualization of the embolus,
2. indirect signs such as:
   1. dilation of the pulmonary artery,
   2. increase in atrial size (AD) and right ventricle (VD),
   3. hypertrophy of the right ventricle in patients with chronic thromboembolism,
   4. left deviation of the interatrial (SI) and interventricular septum,
   5. pulmonary hypertension,
   6. tricuspid regurgitation.

The echocardiogram allows to exclude other serious pathologies that require a different therapeutic path:

1. aortic dissection,
2. rupture of the interventricular septum,
3. right heart attack,
4. Cardiac tamponade (fluid accumulation in the pericardium).

9) Pulmonary scintigraphy: indicated if the examinations of the first category, such as chest X-ray, were inconclusive.

If CT angiography cannot be performed (for example, in chronic renal insufficiency or advanced age). To control the course of the disease.

It can be crucial if the chest X-ray shows no other disturbances and reveals “cold” areas, i.e. areas that have little or no blood flow.

According to the analysis of data from the PISA-PED (Prospective Investigative Study of Acute Pulmonary Embolism Diagnosis), a bandage for careful clinical evaluation, chest X-ray and pulmonary scintigraphy enable diagnosis with high sensitivity (92%) and specificity (87%).

Differential diagnosis

The doctor must exclude:

• Myocardial infarction
• cardiogenic shock caused by left ventricular infarction,
• other causes of right ventricular insufficiency (for example, cardiac tamponade, right ventricular infarction),
• aneurysm dissecans of the aorta,
• acute pericarditis,
• pneumothorax,
• pneumonia,
• Pleurisy.

Treatment of pulmonary embolism

Therapeutic goals are:

• Block thrombus growth → anticoagulant therapy
• Accelerating thrombolysis → fibrinolytic therapy
• Preventing recurrence → long-term anticoagulant therapy

Drug therapy

Anticoagulant drugs do not dissolve the already existing blood clots, but they prevent their increase in size.

Most commonly used drugs are:

• Heparin: is administered through the vein or subcutaneously. Its action is monitored by the aPTT (activated partial thromboplastin time).
• Low molecular weight heparins (LMWH): inactivate factor Xa, have little effect on aPTT; are injected subcutaneously and the effect lasts longer than that of heparin.
• Absolute contraindications: bleeding, recent neurosurgical surgery.
• Relative contraindications: severe arterial hypertension, diabetic proliferative retinopathy, past gastrointestinal bleeding, recent traumatic brain injury, platelet count < 100,000/mm³.
• Warfarin and acenocumarol: are taken orally. They prevent the conversion of vitamin K into its active form and reduce the factors that depend on vitamin K (II, VII, IX, X).
• The full effect occurs after 4-5 days and can be contrasted by the administration of frozen fresh plasma or vitamin K.
• Oral anticoagulant therapy must begin together with heparin and be carried out for at least 48 hours, better 4-5 days at a time and in any case until the therapeutic INR (International Normalized Ratio) is reached with daily control.
• Warfarin is dangerous during pregnancy, so women in other circumstances are only allowed to get heparin.
• Therapy with anticoagulants requires regular monitoring of the active substances in the blood.

Oxygen therapy. In case of hypoventilation and to bind carbon dioxide, this therapy can be carried out on the basis of oxygen.

Aim of mechanical ventilation:

1. Improved gas exchange: reducing PaCO₂ (partial carbon dioxide pressure in the blood) and increasing PaO₂ (oxygen partial pressure in the blood);
2. Improved breathing pattern: increasing ventilation and decreasing respiratory rate;
3. Reducing the work of the respiratory muscles.

Emergency treatment for pulmonary embolism

The patient must be admitted to hospital immediately.

Thrombolytic or fibrinolytic drugs

Doctors immediately begin thrombolytic therapy to dissolve the clot. Thrombolytics are drugs used to dissolve thrombi (blood clots) in emergency situations.

These drugs can cause sudden bleeding in other areas of the body.
Pregnant women are not allowed to receive these drugs.
The risk of bleeding is higher compared to other people.

Reducing or removing the clot with a catheter

The doctor may remove the thrombus through a catheter.
A catheter is a fine flexible tube that is inserted into the upper groin (inguinal) or on the arm.
A vein is used to access the bloodstream to treat the clot in the lungs.
The doctor can:

• remove the coagel,
• inject a drug directly into the thrombus.

Surgery

The procedure to remove the embolus is called embolectomy.
The surgeon:

• performs a thoracotomy (incision on the chest),
• reaches the blood aagel,
• temporarily interrupts blood flow in the tract in front of and behind the embolus,
• cuts in the blood vessel, removes the blood clot and closes the vessel again.

Only rarely is surgical intervention performed. This depends on the clinical picture.

Pulmonary embolism during pregnancy

Pulmonary embolism is one of the causes of death in women during pregnancy.
The risk of pulmonary embolism increases during pregnancy.
Because during pregnancy, there are higher risk factors, including:

• The venous blood flow to the legs is slowed down and the result is a higher risk of blood clots forming.
• Be quiet
• decline in mobility,
• Pregnancy hormones increase the risk of hypercoagulability and the possibility of clot formation.

Women who suffer from deep vein thrombosis have a greater risk of developing pulmonary embolism.
A pulmonary embolism must be diagnosed as soon as possible, because it is life-threatening:

• for the mother,
• for the fetus.

Formation of blood clots after surgery

The formation of blood clots is a common postoperative complication.
After any surgical intervention, one risks developing complications.
The complications most often occur after orthopedic surgery such as:

• knee prosthesis,
• hip prosthesis,
• Joint surgery or interventions after fractures.

Pelvic surgery also causes risks for the formation of blood coagula, as do operations:

• gynaecological in nature,
• urological nature.

Most of these disorders occur:

• in the first 2 weeks,
• up to 12 weeks after surgery.

In some cases, the first symptoms may appear during surgery or a few hours later.
People who are over the age of 40 have a higher risk of forming postoperative blood clots.

Prevention of pulmonary embolism

During the recovery period after surgery, the doctor prescribes anticoagulants until you can walk again and distribute the body weight over both legs.
Physical activity after surgical interventions prevents clot formation.
Long air journeys contribute to the formation of venous thrombosis: patients are advised not to take them after surgery.

How long does the disease last? When is one cured? Prognosis of a patient with pulmonary embolism

If the patient reaches the hospital in time, the survival rate is about 90%.
In the case of a massive pulmonary embolism, the prognosis is infaust because the person often dies within a short time.
After diagnosis, drug therapy must be carried out immediately for at least six months to avoid recurrence.

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