Your patient has a tension pneumothorax after being stabbed. Or maybe it’s a chronic obstructive pulmonary disease patient with a bleb. Honestly, who cares because the breath sounds are unequal and the patient is desaturating. Heck, if this is a board exam, the patient might even have distended neck veins. Even the off-service rotating intern can diagnose this one. But it takes an emergency medicine provider to know what to do and when to do it. You ask for an angiocatheter because you know that a needle decompression is happening and it’s happening now. You’re not scared. In fact, deep down, you’re actually kind of psyched because this is exactly the moment you’ve been trained for. You get that needle, and you get ready to put it exactly where you’ve been taught to put it since you were a mere pup in medical school. Needle decompression of a tension pneumothorax? Second intercostal space at the midclavicular line. You break skin, and you push that sucker in as far as you can. You await that satisfying swish of air. Then, all of a sudden … nothing happens. Your hero moment has been ruined, and quite frankly, you look like an idiot. Oh, and your patient is not doing so well.
Explore This IssueACEP Now: Vol 35 – No 05 – May 2016
It turns out that this was a predictable failure. Why? Because the dogma that the best anatomical location for a needle compression for a tension pneumothorax is in the second intercostal space at the midclavicular line (2nd ICS MCL) is probably bunk. FOAM resources have been onto this for a while, so we covered some of this on a recent episode of FOAMcast.
Back in 2012, Inaba et al published “Radiologic Evaluation of Alternative Sites for Needle Decompression of Tension Pneumothorax,” in which computed tomography imaging suggested that, owing to anatomy alone, choosing the 2nd ICS MCL for needle decompression would be expected to fail 42.5 percent of the time. By comparison, they found that an alternative site, the fifth intercostal space at the anterior axillary line (5th ICS AAL), would only be expected to fail 16.7 percent of the time. The reason makes sense. At the 2nd ICS MCL, the chest wall is simply too thick for standard decompression needles. Clinicians also tend to misjudge exactly where the MCL is, but that’s another story.
We find that one of the most intimidating things about implantable cardiac devices is figuring out what each one does, so we spent some time decoding the alphabet soup of pacemaker function letter codes.
Shortly after this article came out in the Archives of Surgery, Andy Neill wrote a blog post on EmergencyMedicineIreland.com. But when HEFT EMcast, a podcast from the Heart of England Foundation Trust’s Emergency Department in the United Kingdom, revisited this topic, it reminded us that the 5th ICS AAL as the preferred location for needle decompression just hasn’t caught on, so we went through it on FOAMcast. We then discussed a topic that doesn’t get a lot of love in the FOAM world: empyema. Our favorite pearl: in causes of empyema secondary to trauma, the most common bacteria are gram-negative bacilli. Who knew? Well, Tintinalli’s and Rosen’s actually (which we sometimes lovingly refer to as “Rosenalli” on our show).
Secrets of Pacemakers Revealed
Speaking of the upper chest, we spent some time on another recent episode of FOAMcast discussing a post on Dr. Smith’s ECG blog (hqmeded-ecg.blogspot.com) by emergency medicine electrocardiogram guru Stephen W. Smith, MD, professor of emergency medicine at the University of Minnesota in Minneapolis. Dr. Smith has published a couple of case reports showing instances of the use of Sgarbossa criteria in patients with biventricular pacemakers. This is not exactly common practice so far. In fact, almost half of respondents to a recent Medscape poll stated that “one cannot diagnose an infarction from ventricularly paced complexes.” However, Dr. Smith thinks otherwise. While there have not been any large studies to validate his contention, Dr. Smith bases his opinion on “many, many” cases. We used the opportunity to review the modified Sgarbossa criteria and to discuss some finer points of pacemakers and defibrillators.
We find that one of the most intimidating things about implantable cardiac devices is figuring out what each one does, so we spent some time decoding the alphabet soup of pacemaker function letter codes (which can be found on the pacemaker/defibrillator cards that patients carry in their wallets). Every pacemaker has a five-letter code associated with it. Since 2002, the United States and the United Kingdom have used the same letter code for all pacemakers in order to keep things as simple as possible. (We guess the US and the UK have a special relationship after all!) The first three letters are the most commonly referred to letters. The first position tells you which chamber gets paced. The second letter indicates which chamber the pacemaker uses for sensing cardiac activity. The third letter is the “mode of response.” This one indicates how the pacemaker responds to the information it senses. The most common first three letters are VVI (that’s ventricular pacing, ventricle sensing, and inhibition of electric pacing) and DDD (dual chamber pacing, dual chamber sensing, and dual functionality for both the inhibition and the triggering of a pacemaker). While the fourth letter is a little boring (programming settings), the fifth letter in the code is probably our favorite: anti-tachyarrhythmia function.
Many pacers have no anti-tachyarrhythmia functions (denoted as a 0). Some pacemakers pace in response to tachyarrythmias (P). Other pacers can deliver a shock in response to tachyarrhythmias (S). Finally, a pacemaker can have a dual anti-tachyarrhythmia; that’s both shock and pace (D). That’s what we call an “everything but the kitchen sink” pacemaker.
Learn More From FOAMcast
For all of our FOAMcast episodes (which we keep around 20 minutes for your emergency medicine ADHD needs), check out our website.
We also have a couple of free Rosh Review questions with every episode. You can also download the show on iTunes. Our next episode will look at urine toxicology screens and go over some of the most common false positives caused by prescription medications.
As if you needed another reason not to order a u-tox!
Dr. Faust is a senior emergency-medicine resident at Mount Sinai Hospital in New York. He tweets about #FOAMed and classical music @jeremyfaust.
Dr. Westafer is chief resident at the Baystate Medical Center at Tufts University in Springfield, Massachusetts. Follow her @LWestafer.