A pulmonary embolism, frequently abbreviated as a PE, is a blood clot that lodges into the pulmonary vasculature of the lungs. Sometimes this can be asymptomatic, often there are mild-moderate symptoms, and other times patients can go into cardiac or respiratory arrest.
No matter the symptoms, pulmonary embolisms can be deadly, and it is important for nurses to understand this disease and how to treat and monitor your patients with pulmonary embolisms.
This article is part of a new series where we outline various medical conditions and the nursing assessment and management involved with each condition.
Table of Contents
What is a Pulmonary Embolism?
A pulmonary embolism is a blood clot that lodges within the lungs. These are more commonly abbreviated to PEs. These can be very large or very small; only one, or many at the same time.
The larger and more PEs that there are, the more dangerous this can be on the body. This can put significant strain on the heart, and can even cause cardiac arrest.
Remember that a Thombus is one of the Hs and Ts to think about when a patient is coding!
Pulmonary embolism‘s are highly associated with Deep Vein Thrombosis (DVT). You might hear the term VTE, which is an umbrella term for any blood clot within the body including DVTs and PEs.
Causes of a PE
There are many different causes that can cause a PE to develop, but it all goes back to Virchow’s Triad.
Virchow states that in order for blood clots to form within the body, there needs to be at least one of three things:
Stasis of Blood
Anything that causes blood to “sit still”
Damage to the vascular system (arteries & veins)
Something that increases likelihood for clotting
Breaking down Virchow’s Triad, common risk factors for blood clot formation includes:
Stasis of Blood
- Varicose Veins
- Atrial Fibrillation
- Heart Failure
- Elderly Age (>65)
- Recent Surgery (especially orthopedic surgeries)
- Implanted devices
- Central Lines
- Estrogen use (i.e. birth control)
- Inherited genetic predisposition (i.e. Factor V Leidin mutation)
- Severe liver disease
Patients with pulmonary embolisms usually present to the hospital or emergency department with shortness of breath.
This is because an area of their lungs are not able to exchange gas normally. They are able to breathe in adequate oxygen, however they are unable to exchange that oxygen with carbon dioxide wherever the PE is, leading to a ventilation perfusion mismatch.
Symptoms of a PE
Common symptoms of a PE include:
Also referred to as shortness of breath, and may be with exertion or at rest
Usually pleuritic, aka worse with deep breaths or coughing
Usually not productive, but may have pinky frothy or bloody sputum
Syncope with chest pain and SOB is suspicious for PE
Signs of DVT
- Extremity Erythema
- Extremity Edema
- Extremity Pain
Hemoptysis is not nearly as common of a symptom in a PE as your nursing textbook may have led you to think!
The Physical Exam
- Respiratory Distress
- Increased work of breathing
- Use of accessory muscles
- Temp: May have low grade temps
- BP: Normal, increased, or decreased (severe)
- Pulse/HR: Tachycardic
- Respirations: Increased
- SPO2: May be normal or low
- Usually Normal
- May be diminished
- May have crackles if pulmonary infarct or acute CHF
- Pleural friction rub
If a patient has CP/SOB and just recently had surgery or is pregnant, always think PE!
Patients with PEs often have pleuritic chest pain as well, so they’re unable to take full breaths without significant pain. This can increase the respiratory rate as they compensate by taking more frequent, shallow breaths.
Patient’s pulse ox will often be normal unless there is significant respiratory distress. Patients may have a low-grade fever as well.
Patience with PEs will often have tachycardia – which is a heart rate greater than 100 bpm.
Blood pressure is often normal, but may be high secondary to pain. However very large PEs can put significant strain on the heart, causing significant hemodynamic compromise including hypotension and shock.
When auscultating the lungs, a lot of times you aren’t really going to hear any specific bad breath sounds. You may hear some diminishment in the lung with the PE. Sometimes you may hear crackles and rarely wheezing.
Place all patients with chest pain or SOB on a cardiac monitor to detect any arrhythmia that may occur and monitor heart rate.
Patients with PEs will often have sinus tachycardia that does not completely improve with fluid administration.
Patients with PEs can have all sorts of arrhythmias including:
- Atrial fibrillation
All patients presenting with chest pain and/or SOB should have an EKG obtained within 10 minutes of arrival.
This is primarily to rule out any STEMI or ischemia. However, large PEs can cause significant righ theart strain.
While they occur in < 10% of patients, signs of right heart strain on an EKG include:
- Right heart strain pattern
If the patient is significantly hypoxic or tachypneic, apply 2-4 L/min NC. If this is not enough to titrate SPO2 > 90%, apply a non-rebreather.
In these cases, BIPAP or Intubation may be needed.
Start a peripheral IV at least 18-20g in an AC line, as there is a high likelihood that these patients will be needing a CTA. These large bore IVs are needed to inject high-pressure dye.
While drawing blood, make sure to draw a blue top as D-dimer may be ordered, as well as a PT/INR.
Diagnosis of a PE
The Wells’ Criteria for PE is a clinical tool that is able to be used to determine the risk of a PE.
This assigns points to each of the following:
- Signs of DVT: 3 points
- PE #1 likely dx: 3 points
- HR > 100 bpm: 1.5 points
- Immobiilization x 3 days: 1.5 points
- Surgery within 4 weeks: 1.5 points
- Previous PE/DVT dx: 1.5 pnts
- Hemoptysis: 1 point
- Malignancy w/ tx in last 6mo or palliative: 1 point
Once you calculate their score, you can stratify their risk into one of the following:
- Low risk: 0-1 point
- Moderate: 2-6 points
- High risk: >6 points
Scores of 4 or less with a negative D-dimer can effectively rule out a PE.
One way to minimize radiation is to obtain a D-Dimer in a patient with low to moderate suspicion of a PE.
A D-dimer is a byproduct of fibrin which is increased in the blood whenever there is a blood clot.
While this is a great test to see if there is a possibility of blood clots within the body, it is not very specific. This means that a negative D dimer (less than the threshold) is a pretty good way to tell if someone doesn’t have a blood clot. However, a positive D-dimer doesn’t necessarily mean there IS a blood clot in the body.
Any bruise or minor injury can cause elevations in D-dimer, as well as pregnancy, heart disease, infections, and more.
This means that if a D-dimer is above the threshold (around 230 but depends on your lab), then the Provider is pretty much forced to get a CTA to see if their truly is a PE.
If a D-dimer is less than the threshold, then a PE can usually be ruled out. However, this is only the case is clinical suspicion is low to moderate.
In patients who have a high liklihood of a PE, a D-dimer can miss a PE up to 15% of the time!
Other Lab Work
A troponin should be ordered in patients with chest pain and/or SOB. This can sometimes be mildly elevated in PEs, or significantly elevated if a PE causes a STEMI or NSTEMI.
A BNP may be ordered if there are s/s of heart failure.
Renal function should be checked before a CTA can be done, to make sure their kidneys can handle the dye. A GFR > 30 is usually adequate to obtain a CTA.
Coagulation studies may be performed inpatient to see if there are any genetic mutations predisposing the patient to forming thrombi.
An ABG may be obtained if the patient is in significant respiratory distress or has altered mental status.
With a PE causing significant distress, you’ll typically see the following results on an ABG:
- PaO2: Low (<80 mmHG)
- PCO2: Low (<35 mmHG)
- pH: Alkalotic (> 7.45)
- HCO3: May be low (<22 mEq)
A chest x-ray (CXR) will almost always be ordered on patients who are suspected of having a PE, because these can rule out some other causes of chest pain and SOB such as a pneumothorax or pneumonia.
However, a CXR is not going to pick up a pulmonary embolism. A CXR may show nonspecific signs including atelectasis or effusions, but often will be completely normal.
In order to actually see the pulmonary embolism, a CT pulmonary angiography (CTPA or just CTA) is required.
Angiography is when a radiopaque dye is injected into the patient’s vein in order to get a good look at the patient’s vasculature during a CT scan. This can be timed to look at specific areas of the heart.
CT Pulmonary Angiography is when this is done to look at the pulmonary arteries and veins. This means the radiologist can directly visualize pulmonary embolisms.
If the patient’s GFR is <30, we generally avoid contrast dye. However, this may be completely facility dependent.
If a patient cannot be given the dye (GFR < 30 or anaphylactic reaction), the alternative test is to obtain a V/Q Scan.
A VQ scan is a nuclear medicine test where they use radioisotopes in conjunction with X-rays to see if there are any ventilation/perfusion mismatches. Well this is not as definitive as a CTA, it does give probabilities of their being a PE, such as a “very low probability”.
The patients CXR really should be a clear study, otherwise the VQ scan will be poor quality. So if the patient has significant consolidation or pleural effusions, the VQ scan is unlikely to be very sensitive to finding a PE.
Treatment of PE
Treatment of a patient with a PE who is hemodynamically stable will generally consist of admission to the hospital, parenteral anticoagulation, and then transition onto an oral anticoagulant.
Patients who have significant hemodynamic compromise may require reperfusion therapy.
Treatment for pulmonary embolisms primarily involve anticoagulation.
In the hospital setting this is usually IV unfractionated heparin. This Heparin is given as a Heparin drip, which is titratable depending on PTT levels. Each facility should have their own heparin drip protocol.
In general, a bolus dose is given IV (can push fast), and then a slow drip is started. The PTT levels are usually checked every 6 hours but will depend on the protocol.
SQ Lovenox is an alternative to IV heparin, and is given in a dose of 1mg/kg BID.
But how does anticoagulants really help if the blood clot is already there? The role of the anticoagulants are to prevent further clots from forming, as well as to stabilize the clot from moving. This can be especially helpful if there is a DVT or an atrial thrombus within the heart. These can embolize and cause further PEs or even strokes.
I’ve found that usually IV heparin is ordered because this is more easily titrated and can be stopped quicker in case there is any bleeding or procedure that need done while inpatient.
Sometimes the patient can be started directly on an oral anticoagulant and discharged home if they are otherwise stable, but this will depend on the Provider and the facility standards.
Once the patient is stable enough for discharge, they are started on long-term oral anticoagulation, such as Eliquis or coumadin.
Patients with very recent surgery, hemorrhagic stroke, or active bleeding are not started on anticoagulation.
Patients will often need to stay on the anticoagulation for at least 3 months, but sometimes longer. The blood clot should be reabsorbed by the body in about 6 weeks, but will depend on the size of the thrombus.
Some patients will require life-time anticoagulation if they are found to have any genetic predispositions to blood clots. This is also true for patients with atrial fibrillation.
An inferior vena cava filter, commonly referred to as an IVC filter, is a device that is sometimes placed to “catch” clots before they enter the right atria.
This is usually placed in for patients who cannot be on anticoagulation, or those who have gotten repeat PEs despite anticoagulation therapy.
They can be temporary and need removed eventually, but some that are placed are permanent.
In patients who are hemodynamically unstable from their PE, thrombolytic therapy can be given to dissolve the clot. This is like TPA in a stroke, but given for a PE.
However, there are many contraindications to thrombolytic therapy, and there is a risk of bleeding.
An Embolectomy can be performed if needed and if the facility is capable of doing so, particularly when thrombolytic therapy is unsuccessful or cannot be used due to contraindications.
There are additional procedures that can be done to retrieve / break up the clot including:
- Ultrasound-assisted thrombolysis
- Rheolytic embolectomy
- Rotational embolectomy
- Suction embolectomy
- Thrombus fragmentation
- Surgical embolectomy
Many facilities will not have these capabilities, but most should have thrombolytics.
A Saddle pulmonary embolus is a very large PE located at the bifurcation of the main pulmonary artery. These PEs are rare but likely to cause significant hemodynamic compromise and cardiopulmonary respiratory arrest!
Monitor their oxygen status by respirations and pulse oximetry. Stable patients may only need q4h vitals.
If their oxygen is low or if there is significant respiratory distress, titrate up their oxygen levels.
A BIPAP or Intubation may be needed in severe cases.
Blood Pressure Support
Monitor their blood pressure per department protocol.
If hypertensive, treat with analgesics and antihypertensives.
If hypotensive, treat with fluid boluses, paying careful attention to respiratory and cardiac status.
Vasopressors may be required in severe cases.
These patients should have telemetry ordered.
Monitor their cardiac rhythm per department protocol, and notify any changes to the Provider.
Bleeding / Falls
These patients are usually placed on anticoagulation as above. Be sure to place the patient on fall precautions, and monitor for any bleeding.
Titrate the heparin drip according to protocol, and a high PTT may require that you stop the heparin drip for some time.
If the patient begins to deteriorate, be sure to notify the physician or APP and/or call an RRT.
Remember that PEs put strain on the heart, so patients can go into flash pulmonary edema. Those with pre-existing CAD may have heart attacks.
Do you have any crazy PE stories? Let us know in the comments below!
Haag, A., et al (2022). Pulmonary embolism. In R. I. Donaldson (Ed.), WikEM, The Global Emergency Medicine Wiki. https://wikem.org/wiki/Pulmonary_embolism
Sharma, R. (2022). Pulmonary embolism | Radiology reference article. Radiopaedia.org. Retrieved February 8, 2022, from https://radiopaedia.org/articles/pulmonary-embolism
Tapson, V. F., & Weinberg, A. S. (2022). Treatment, prognosis, and follow-up of acute pulmonary embolism in adults. In T. W. Post (Ed.), Uptodate. https://www.uptodate.com/contents/treatment-prognosis-and-follow-up-of-acute-pulmonary-embolism-in-adults
Thompson, B. T., Kabrhel, C., & Pena, C. (2022). Clinical presentation, evaluation, and diagnosis of the nonpregnant adult with suspected acute pulmonary embolism. In T. W. Post (Ed.), Uptodate. https://www.uptodate.com/contents/clinical-presentation-evaluation-and-diagnosis-of-the-nonpregnant-adult-with-suspected-acute-pulmonary-embolism
Thompson, B. T., & Kabrhel, C. (2022). Overview of acute pulmonary embolism in adults. In T. W. Post (Ed.), Uptodate. https://www.uptodate.com/contents/overview-of-acute-pulmonary-embolism-in-adults
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