Pulmonary Embolism: Diagnosis

00:00 So when we’re thinking about other testing for patients in whom we’re thinking about a pulmonary embolus, we wanna go back and start thinking about keeping our differential broad.

00:10 So we’re thinking about a pulmonary embolus but we also wanna make sure we’re thinking about other things potentially as well.

00:16 So we wanna do our basic lab work.

00:18 We wanna get an EKG to assess for any evidence of ischemia, to assess for an arrhythmia.

00:24 Often times when patients come in with shortness of breath or chest pain, for the most part they’ll get a chest x-ray to take a look and make sure there’s not something else causing it.

00:33 So chest x-rays can show you if there’s pneumonia, if there is a pneumothorax, if the lung has collapsed.

00:38 You potentially might wanna get a troponin if you're thinking about a pulmonary embolus.

00:43 A troponin is helpful to evaluate for acute coronary syndromes but also in patients who have large pulmonary embolus.

00:49 They can have a positive troponin due to the fact that there’s strain placed on the heart.

00:55 You potentially consent a pro-BNP.

00:58 Pro-BNP is thought to be a marker of a strain on the heart as well and also heart failure and can be elevated in patients who have pulmonary embolus.

01:08 And then our PE specific testing, so the D-dimer is the screening blood test for pulmonary embolus and as a screening test we send it and if it’s negative we’re done and if it’s positive then we need to go ahead and do additional testing.

01:23 The last test that we do for pulmonary embolus is a CT angiogram of the chest or VQ scan, and these are more advanced imaging techniques than a chest x-ray.

01:33 The CT angiogram takes a look at the blood vessels very closely and it’s a CT scan that’s done with IV contrast and it’s a good test to look for pulmonary embolus.

01:44 And if the patient is unable to get a CT angiogram of the chest, they can get a VQ scan and we’ll talk about both of these studies in a moment.

01:52 So let’s go back to calculating our risk score.

01:56 Now we mentioned if our patient is PERC negative, they have a less than 2% risk of pulmonary embolus and for this patient who fall into this category there is no indication for additional testing.

02:06 For a patient who is Well’s criteria low risk, for those patients we wanna think about D-dimer testing, so someone is positive in the world of PERC and they are low risk in their D-dimer score, we can go ahead and get a D-dimer.

02:23 If the D-dimer is negative, you can likely stop your work up.

02:26 For patients who are moderate or high risk in Well’s criteria, those are patients who need additional imaging.

02:34 You don’t wanna send a D-dimer in those patients because you already have a higher suspicion that the patient may have a pulmonary embolus.

02:40 So when they fall into that category where they’re moderate or high risk in Well’s, for those patients you can get a CT angiography as the initial testing for pulmonary embolus.

02:49 For patients who can’t get a CT angiography study, they can get a VQ scan.

02:55 So patients who can’t get a CT angiography are patients who potentially have renal disease because it does involve IV contrast and IV contrast is contraindicated in patients with severe renal disease.

03:08 Our patients who are allergic to IV dye also cannot get CT angiography.

03:14 You know, subset of patients who is always a little bit controversial about what imaging study to get are pregnant patients.

03:20 Pregnant patients, generally, CT angiography is actually recommended.

03:25 Meaning, you always wanna make sure that you discuss that with your patient because it does expose them to some radiation and as well as the baby to some radiation.

03:33 But we generally will recommend CT angiography because it can tell you if there’s a pulmonary embolus there but can also tell you whether or not there is other stuff going on in the lungs that might not necessarily have been seen on the chest x-ray.

03:45 VQ scan does have some limitations that we’ll talk about in a moment.

03:49 Now, I just wanna be clear here that one thing that’s very important to think about is that you are thinking about your clinician gestalt.

03:56 So we have all of these decision rules but actually there have been lots of studies that show that clinician gestalt, so whether or not you think that the patient has a PE, is actually sometimes performs better than any of these testing.

04:09 So we talk about these tests a lot and these decision rules a lot but really using your medical instincts can sometimes really serve you well in this situations.

04:19 So definitely make sure you’re using these decision rules but as you get on in your training and in your careers, your clinical gestalt can really serve you quite well.