04.02 Pulmonary Embolism

First things first, what is a PE? A PE happens when something occludes one of the pulmonary vessels. Most often, it's a venous thrombus that dislodges and travels through the vessels, through the right side of the heart, and into the pulmonary circulation. These thrombi can come from anywhere but they most commonly start as deep vein thrombosis in the lower extremities.

So there are numerous risk factors. These can include any incidence of a previous DVT, Any sort of surgery in the last 4 weeks, use of estrogen replacement, active or metastatic cancers, which can actually cause a thrombus of the tumor to break off. Recent long term travel, you know like a flight from Hawaii to New York. And really this speaks to the immobility factor. IV drug use can cause a thrombus and as we get older we are more at risk.

These patients, while they can exhibit symptoms that may steer us in any number of directions, do have a few very telling signs that should alert us to a PE. Many times the symptoms are nonspecific. They can have some trouble breathing, some rapid breathing and a little red tinge to the sputum. They can have a sudden onset of pleuritic chest pain, basically, it hurts to breathe. So what happens when you can't breathe and it hurts with every breath, well your going to get anxious which is going to increase your heart rate. If we suspect a PE we need to look for signs of a DVT like leg swelling or that pain behind the knee. There can also be some very atypical signs but if we focus too much on those it can actually distract us from the main issue.

We want to diagnose so to do that we are going to need some tests. Chest X-ray is a no brainer. Get that line in and get someone to get an arterial blood gas to see if they are in respiratory acidosis. When we get some labs, we want to run a D-Dimer. This is usually done to determine the possible presence of a PE. Usually if its below 500, then you are safe. Over 500 doesn't mean that the PE is definitive, but it does warrant further testing like a CT or an MRI or MRA. You also want to get an ultrasound to the leg to see if there is any DVT still lurking.  And we will also need to get a 12-lead EKG mostly to rule out the possibility of an active myocardial infarction or some other cardiac abnormality.

No once the diagnosis of PE has been confirmed, we need to treat. Always start with the basics. Get some O2 on them and get a line in. We also want to keep a close eye on their vital signs, specifically the oxygen saturation and if you have it, capnography. 

In order to prevent further formation of clots or enlarging of the current blockage, we will start IV heparin therapy. There are specific weight-based formulas for this and hopefully, your facility has these written down somewhere. If not, enlist the help of your pharmacy. 

If the blockage is so severe that it needs immediate removal, there is the possibility of using the clot buster, tPa. If we need more invasive interventions, we can send these patients to the cath lab for an angiogram and clot retrieval. 

We need to use our clinical judgment here to determine if this is a PE of some other disorder. Oxygenation is key as the lungs are getting cut off from the blood supply. And we need to prioritize in order to treat properly. Don't get the EKG before putting on some oxygen, know what should happen first.