The perks of PERC

The really worrying question sometimes arises (or depending on your luck, most times arises) while you are in an ED, and you see a patient who comes in with ‘some chest pain’ that’s maybe a little pleuritic in nature, but pleuritic chest pain could result from a punch to the chest, or if you cough too hard or too long (I unfortunately speak from experience!) and you don’t know what to do and someone’s already done a D-Dimer on the patient’s initial bloods as they were triaged, before you saw them, if you are lucky enough to work in a department as great as ours (or unlucky, depending on how you view the over-testing of D-Dimers!) – I have been handed the most amazing tool: the PERC score, or the Pulmonary Embolism Rule-out Criteria. For those of you already aware of the existence of such a magic wand – bravissimo and kudos to you, and no need to read on any further. For the ones like me who until very recently hadn’t even heard of it, please proceed further.

Patients who present with clinically low risk for development of a PE can be subjected to the PERC. This is a pre-test probability type situation, whereby you assess a patient based on clinical parameters (which you obviously already do!) but you mentally check them off a list of specific parameters, and if they meet all 8 (yes EIGHT!) criteria, then you can safely say they do not need further assessment RE:pulmonary embolism, D-dimers, CTPA route etc. This creates a warm and fuzzy feeling in me, because almost every patient in the past 3 years of practising emergency medicine in the UK that presents even remotely with pleuritic sounding chest pain, regardless of whether they have a clinical indication or not, automatically had a D-dimer, and, God forbid, should they have an ever-so-slightly-raised D-dimer level, they were referred to the acute medical team faster than you could say enoxaparin. These were then possibly unnecesarily given doses of enoxaparin, until the gold standard rule-out test could be performed, which is the CT PA (CT pulmonary angiography). That’s just the way things worked, because a positive D-dimer can indicated possible pulmonary embolism, but it needs to be taken with the complete clinical picture, and a (very large) grain of salt. D-dimers can, unfortunately or fortunately, be raised in a number of different situations, e.g an underlying active malignancy (which gives the double whammy of raising your chances of getting a PE in the first place), an infection anywhere in the body, certain medications and inflammatory medical conditions. ┬áThis lead to over treatment of many patients with anticoagulants till the CTPA was performed to finally confirm the existence or absence of the offending clot. Things may have changed for the better with the PERC, though.

The parameters you base your PERC score on are Age (< 50 years), O2 sats (greater than or equal to 95%), Heart Rate (less than 100 BPM), Absence of Hemoptysis, Absence of Oestrogen usage (Contraceptive pills), Absence of history of surgery/trauma requiring hospitalisation/immobilisation within past 4 weeks, Absence of lower limb swelling (unilateral), and absence of prior personal history of clots/emboli/thrombi.

These parameters and this score are widely used now and available as calculator/apps on most phones.

So the way I understand is, low-risk patients meeting the PERC score criteria need not be further assessed (even if they have had a D-dimer done that’s slightly raised, you can ignore it because the pre-test probability was extremely low). Low-risk patients not meeting the PERC criteria may then go on to be assessed on the D-dimer route, and the high risk patients go directly to CTPA without faffing around with PERCs and WELLS and GENEVAs.

Good luck, and happy PERC-ing!

The chest pain that just…kept on giving!

I had the pleasure of seeing this patient, elderly around 75-80 year old male, and you know how you sometimes really connect with someone? Hit it right off even if you are in a hospital cubicle and they’re in pain and you’re the doctor and the nurse is connecting the ECG electrodes to their chest and you are holding their hand? No? Never happened to you guys? Hmmm.

Well, as I said, I had the pleasure of picking up this patient’s card. He had come in with chest pain, that had begun that evening, and he was concerned enough to call an ambulance. His past history was significant for hypertension (high blood pressure) for which he was on x 2 medications, and angina (chest pain, cardiac in origin, usually when you exert yourself, and relieved by rest and/or some medication under the tongue, does not signify lasting cardiac damage, but does signify some degree of cardiac disease). He also had a family history of cardiac disease.

He was otherwise very fit and well, jogged and took his dogs for walks etc daily. Non smoker. He hadn’t had an episode of angina in the last few years, but for the past 2-3 weeks he was having recurrent chest pains, that initially seemed like his usual angina (started on exertion, relieved by rest) but then progressively began to occur with less and less exercise and now for the past 2 days he had had episodes of chest pain at rest, and this latest episode he was lying in bed, reading! On arrival to ED his observations were all within normal limits, and his ECG was within normal limits – slight changes but when compared to a previous one we had on record it was essentially the same. There were no significant findings one examination and his blood tests and CXR were within normal limits. Even so, he was having chest pains with gradually decreasing amounts of exertion, and also at rest (his angina had progressed to a variant known as unstable angina) – he was going to have to stay in hospital for observation, further investigation and a cardiology opinion about whether or not he needed to have an angiogram done. When I broke the news to him, the rather stoic-appearing gentleman became teary-eyed and red-faced; he was quite upset at the thought of having to stay in hospital. I assured him there was nothing horribly horrendous going on, but we were trying to do whatever was the safest course of action for him. He understood of course, but he was still quite reluctant to stay. His wife finally convinced him to stay, and I referred him on to the cardiology unit. And that was that. Or so I thought.

3 weeks later, I picked up a card for the next patient who had come in with chest pain. The name didn’t ring a bell – you see so many patients on a daily basis, it would be impossible for every patient’s nomenclature to remain in your mind’s database. As I stepped in to the cubicle and pulled the curtains behind me, I opened my mouth to introduce myself but the patient beat me to it by exclaiming that he had seen me before – that he was one of my regulars now. I still didn’t recognize him but he then proceeded to outline what had happened on his last attendance, and it became clear: this was the same patient. I asked him what had brought him to ED this time. He reported he had been out of hospital only a week. “Wait a minute, hang on, you say you were discharged just a week ago? But I admitted you ages ago, have you been in hospital all this time?” I was incredulous. He smiled and told me he had had an angiogram during his previous admission, and found to have ‘a lot of clogged arteries’ so he was referred to nearby cardiothoracic surgery hospital for a Coronary Artery Bypass Graft – or CABG, better known as a heart bypass – 2 weeks back! I was shocked, and at a loss for words, and didn’t really know how to proceed with the conversation. Here was a guy who had come in with chest pain not 3 weeks ago, and I had admitted him for observation and further investigation, yet he had somehow had a bypass done in the interim, and also now ironically come back with some more chest pain – anginal symptoms to be exact! Which is unusual, because a CABG would treat the exact anginal symptoms he used to have, and for him to have the misfortune of having cardiac-sounding chest pain, that begins at exertion and relieves at rest (the reason he presented this time) and for him to actually end up in hospital with it; coupled with the misfortune of seeing me as his doctor, again, when I had been the harbinger of bad news previously – it really couldn’t get any worse now, could it? I went about asking him for a detailed history of the events causing him to attend this time, and examined him fully. His ECG showed some changes, but I was unsure if this was now normal for him, since he had recently had cardiac surgery (not two weeks ago!!!). He was currently pain-free, and at no point during the chest pain episode this time did he have any shortness of breath, and no coughs or fevers. Pain was reproducible on palpation of sternum (following chest recently being cracked open, that wasn’t really an unusual finding). He did not have any difficulty taking in deep breaths and the pain did not recur or increase with taking deep breaths – it was non pleuritic and so I basically ruled out a clot on the lungs in his case base on symptoms. He wasn’t even tachycardiac. The holy trinity of a pulmonary embolism or a clot on the lungs is surgery or immobilization for the past few days, chest pain associated with shortness of breath and tachycardia, with an increase in pain on taking a deep breath. He did report some pain and swelling of his left lower leg but that was normal in someone who had only a few days previously had had surgery to remove one of the long veins of his legs to use as a bypassing vessel in his heart – the wound itself was healing and dry, and did not look infected; he reported the swelling was improving since his surgery. I did a baseline set of bloods, including a troponin (enzyme that leaks into blood upon cardiac muscle damage) which came back slightly raised at 28 (normal range is below 14) and it was probably still coming down from his recent cardiac events. I added d-dimers to his bloods – and they came back as positive at 2700 (normal range is less than 230) but they can be raised in many conditions, including pulmonary embolism but also major surgery, pregnancy and infection. The D-dimers seemed to be in keeping with someone who had recently had major surgery, but I still spoke to the medical registrar – I was not going to administer anticoagulants to someone who had just had cardiothoracic surgery! They requested a CT scan of the pulmonary vasculature with contrast, and diagnosed pulmonary embolism.

To this day he remains my only patient who really tested all my differentials of chest pain during our multitude of interactions – I considered him to have at least 4 causes of chest pain at different points in time: Angina (prior history); Unstable angina/ACS (first visit to hospital); Musculoskeletal chest pain (tender anterior chest due to surgical wound); and pulmonary embolism. Wow.