Diagnosis of pulmonary embolism
It is not easy to diagnose pulmonary embolism because the symptoms are generic.
The first thing that must be done is the medical examination, then the prescription of some exams.
1. Blood tests can help determine if a person is more likely to develop diseases such as deep vein thrombosis or pulmonary embolism, but is unable to detect the clot.
The most important thing to evaluate in the blood test is D-dimer , that is a fibrin degradation product.
When a blood clot is formed, the plasmin breaks down the fibrin structure, then produces the D-dimer.
In 90% of cases of pulmonary embolism it is> 500 ng / ml. If it is normal, you are sure there is no deep venous thrombosis, but if it is positive, it does not indicate otherwise.
Troponin : is very sensitive and specific for myocardium ( acute myocardial infarction ,heart failure , acute pericarditis , myocarditis, hypertensive heart disease). Elevated troponin levels may also be associated with pulmonary embolism caused by right ventricular anomalies.
2. Arterial blood gas analysis (GA) is an exam used to evaluate the partial pressure of oxygen and carbon dioxide in the blood. It is not accurate for this disease because there are other diseases that can affect those values.
In most cases, the patient with pulmonary embolism also has hypocapnia (low concentration of CO2 in the blood).
Instrumental exams of images
2) Angiography , for this test is used a contrast liquid that allows to see the plunger directly and exclude other lung diseases, such as pleural effusion . In most patients, there are multiple strokes.
3) Pulmonary angiography : Until 2003, it was considered the gold standard for the diagnosis of pulmonary embolism. It is actually the most sensitive and specific method (the incidence of false negatives is only 1%). The doctor injects a contrast medium and can see if there is a complete obstruction of a vessel or a vessel filling defect. In addition, there are indirect signs, such as deceleration or decreased flow and delayed venous flow.
An important advantage is the possibility of performing local fibrinolytic therapy through the angiographic catheter.
However, it is an invasive exam where the catheter passes through the heart valves . The main complications are arrhythmias , cardiac perforation, acute renal failureand respiratory. Spiral or helical tomography is now a great alternative.
4) Angio CT of the thorax : the spiral technique allows to continuously acquire the images of an entire organ quickly. It has a sensitivity of 95.5% and a specificity of 97.6%. It became the most widely used second-level exam. If the test is negative, it excludes the possibility of significant embolism in the next 6 months, then anticoagulant therapy is avoided. Some advantages include:
- Execution speed,
- Allows to exclude the infarct,
- It is less invasive and causes fewer complications than pulmonary angiography.
In tomography (figure below), at the level of white blood vessels you can see:
- Gray spots if the artery is partially obstructed,
- Black spots if the artery is completely blocked.
5) Pulmonary MRI : used in selected cases (eg in case of absolute contraindications to spiral CT).
6) Color Doppler ultrasonography is used to control blood flow in the leg veins and to identify the formation of blood clots in the lungs .
7) The electrocardiogram ( ECG ) is useful in case of pulmonary embolism, as it may show a right ventricular hypertrophy.
In 70% of cases it is abnormal but is not specific for embolism, so it is crucial to compare it with a previous examination. You can have:
- Sinus tachycardia ,
- Abnormalities in cardiac rhythm ( extra-systole , atrial fibrillation ),
- Signs of right ventricular overload.
8) Echocardiogram : All patients with suspected pulmonary embolism should perform an emergency echocardiogram. This method showed a sensitivity of 87% and a specificity of 100%.
The exam may show:
- Direct signs of pulmonary embolism, such as visualization of the plunger,
- Indirect signals such as:
- Dilation of the pulmonary artery
- Increased right atrial (RV) and right ventricular (RV) diameter
- Right ventricular hypertrophy in patients with chronic thromboembolism
- Deviation to the left of the interatrial septum (SI) and interventricular septum
- Pulmonary hypertension
- Tricuspid valve insufficiency.
The echocardiogram allows the exclusion of other serious pathologies that require a different therapeutic route:
- Aortic dissection,
- Interventricular septum rupture,
- Right myocardial infarction,
- Cardiac tamponade (accumulation of fluid in the pericardium ).
9) Pulmonary scintigraphy – It is indicated: If the first level examinations like the chest radiography do not eliminate any doubt.
If angioCT can not be performed (eg in chronic renal failure , very advanced age), to control the course of the disease.
It may be crucial if the chest X-ray shows no other disturbance, it can detect “cold” areas, that is, with little or no perfusion.
By analyzing the PISA-PED data ( Prospective Study Investigative Diagnosis of Acute Pulmonary Embolism ), the combination of careful clinical evaluation, chest x-ray and scintigraphic diagnosis allows to achieve high sensitivity (92%) and specificity (87%).
The doctor should exclude:
- Myocardial infarction,
- Cardiogenic shock of left ventricular infarction,
- Other causes of right ventricular failure (eg, cardiac tamponade, right ventricular myocardial infarction),
- Dissecting aortic aneurysm ,
- Pericardite aguda,
- Pneumothorax ,
- Pleurisia .
What is the treatment for pulmonary embolism?
The therapeutic objectives are:
- Block thrombus growth → Anticoagulant therapy,
- Accelerate thrombolysis → Fibrinolytic therapy,
- Prevention of recurrences → Long-term anticoagulant therapy.
The anticoagulant drugs do not dissolve existing clots, but avoid the increase in size.
The most commonly used drugs are :
- The heparin is administered intravenously or subcutaneously. The activity is monitored with the APTT (Activated Partial Thromboplastin Time).
- Low molecular weight heparins (LMWH) : inactivate factor Xa, have little influence on aPTT. Injections are subcutaneous and the effects last longer than heparin.
Absolute contraindications: hemorrhage , recent neurosurgical intervention.
Related contraindications: severe arterial hypertension , diabetic proliferative retinopathy , recent gastrointestinal bleeding, recent head injury , platelets <100,000 / mm3.
- The warfarin and acenocoumarol : they are taken orally . They inhibit the conversion of vitamin K into active form and therefore reduce the factors that depend on vitamin K (II, VII, IX, X).
The effect occurs after 4-5 days and can be neutralized by administration of fresh frozen plasma or vitamin K.
Oral anticoagulant therapy should begin with heparin and continue for at least 48 hours, best for 4-5 days, in any case up to to achieve the International Normalized Ratio (RNI) values with daily monitoring.
Warfarin is dangerous during pregnancy, so pregnant women can take only heparin.
Anticoagulant drug therapy needs regular monitoring of levels of the active substance in the blood.
Anyone who interrupts heparin treatment before has many chances of recurrence and develops secondary pulmonary hypertension due to numerous recurrences of pulmonary embolism.
In practice, in the case of eminodimously stable pulmonary embolism, the guidelines are:
- Injection of UFH (unfractionated heparin) 5000 IU
- Clexane (enoxaparin sodium) 100 IU / kg (0.1 ml / 10kg) every 12 hours or 150 IU / kg once daily
- Immediately combine Coumadin (warfarin), 1 tablet daily
- Continue with LMWH for at least 5 days
- Stop HBPM if you RNI> 2 for 2 consecutive days.
Thrombolytic therapy is performed in case of:
- Massive or sub-massive pulmonary thromboembolism,
- Acute pulmonary thromboembolism with shock or hemodynamically unstable disease confirmed with echocardiogram,
- Patients with chronic heart or lung diseases.
Streptokinase, urokinase and recombinant tissue plasminogen activators (r-TPAs) are thrombolytic drugs that cause generalized fibrin degradation.
For hypoventilation and retention of carbon dioxide this oxygen-based treatment can be done.
Objectives of mechanical ventilation:
- Improve gas exchange: lower PaCO2 (blood carbon dioxide pressure) and increase PaO2 (blood oxygen
- Improve respiratory pattern: increases ventilation and decreases respiratory rate,
- Reduce the work of respiratory muscles.
Emergency treatment for pulmonary embolism
The patient should be admitted to the hospital immediately.
Thrombolytic or fibrinolytic drugs
Doctors rely on thrombolytic therapy to dissolve the clot. Thrombolytics are medicines used to dissolve thrombi (blood clots) only in emergencies.
These medicines can cause sudden bleeding in other areas of the body.
Pregnant women are not treated with these medications.
The risk of bleeding is greater than other individuals.
Reduction or elimination of the clot with the catheter
The doctor can remove the clot with the aid of a catheter.
The catheter is a small flexible tube inserted into the upper thigh (groin) or arm.
Through a vein it enters the bloodstream to treat the blood clot in the lung.
Your doctor can:
- Remove the clot,
- Inject thrombolytic medication directly.
The surgery to remove the embolism is called a surgical embolectomy.
- Perform a thoracotomy (incision in the chest),
- It arrives at the blood clot,
- Temporarily stops the flow of blood in the tract before and after the embolus,
- Cut the blood vessel, remove the clot and repair the glass.
Rarely is the surgical treatment chosen, depending on the clinical picture.
Pulmonary Embolism in Pregnancy
Pulmonary embolism is one of the leading causes of death in women during pregnancy.
Increases the risk of blood clots forming in the lungs during pregnancy.
This is because during pregnancy there are major risk factors, for example:
- The venous flow of the legs decreases and the consequence is a greater risk of clot formation,
- The home,
- The decrease in mobility,
- Pregnancy hormones increase the risk of hypercoagulability and the likelihood of clotting.
Women who suffer from deep venous thrombosis are at a greater risk of having pulmonary embolism.
Pulmonary embolism should be diagnosed as soon as possible, as this is life threatening:
- From the mother,
- From the fetus.
Post-surgery blood clots
The formation of blood clots is a frequent postoperative complication.
After any surgical procedure there is a risk of developing some complications.
Complications are more common after orthopedic surgery, such as:
Even pelvic surgeries cause a risk of blood clots, such as operations:
Most of these problems manifest themselves:
- In the first 2 weeks,
- Up to 12 weeks after surgery.
Some individuals may have the first symptoms during the surgical procedure or a few hours later.
People over the age of 40 have a high risk of developing blood clots in the postoperative period.
In the convalescence phase after surgery, the doctor prescribes anticoagulants until he / she begins to walk putting the weight in both legs.
Physical activity after surgery is for the prevention of blood clots.
Long-term air travel contributes to the risk of deep vein thrombosis: patients are advised to abstain after surgery.
How long it takes? The prognosis of patients with pulmonary embolism
If the patient arrives at the hospital, the survival rate is about 90%.
In the case of massive pulmonary embolism, the prognosis is poor because often the individual dies within a short time.
After the diagnosis, it is necessary to undergo the drug treatment for at least six months to avoid a recurrence.