Pulmonary embolism, or PE, is the obstruction of one or more branches of the pulmonary artery. It can strike abruptly and cause sudden death.
The number one risk factor for PE is deep vein thrombosis, or DVT. The risk for DVT and PE is high during periods of prolonged immobility after surgery.
With DVT, a blood clot, air bubble, or fat particle breaks free from the lower extremity veins, becoming an embolus. It travels to the lungs, where it can obstruct a small artery or arterial branch. The pulmonary artery is a major highway for oxygen exchange. So a blockage in this highway means that oxygen cannot get to vital organs. This is called hypoxemia or alveolar hypoventilation.
Prolonged immobility is the most common cause of DVT, as immobility causes blood to pool, a condition known as venous stasis.
Because symptoms are fairly general, PE can be difficult to identify. The patient may experience rapid breathing and heart beat along with sharp, sudden chest pain.
When a patient presents with these symptoms, provide oxygen first, and attach an ECG monitor to assess for a heart attack. Then give IV saline to dilute the blood and address any possible clot until the patient gets a definitive diagnosis.
Stat labs will be drawn, including those for arterial blood gases and D-Dimer, a specific blood clot enzyme.
BNP, which is B-type natriuretic peptide, is tested to rule out heart failure.
The best test for PE is the computed tomography scan with contrast. If this is unavailable, a VQ, or ventilation-perfusion scan, shows areas of the lung that are not receiving enough oxygenated blood. Chest X-ray may also be used to rule out other causes of respiratory distress.
After PE diagnosis, the patient receives IV anticoagulants such as heparin. This prevents new clots from forming. To reduce the clot size, the patient may also receive a thrombolytic agent such as Alteplase.
The patient's partial thromboplastin time, the length of time it takes blood to clot, is monitored to make any needed dose adjustments. Dosages of medications will vary based on patient's weight and lab values.
Finally, Protamine sulfate should be available to reverse heparin effects in case of active bleeding.
With acute massive PE and hemodynamic instability where the patient cannot take thrombolytics, surgical removal of the embolus may be considered.
PE is fatal for up to 30 percent of those diagnosed. Prompt medical treatment increases survival rates significantly. For patients who survive, education is necessary to prevent recurrence.