Know Thy Shelf: Surgery Edition (Part II)
- Feb 03, 2016
As promised, the thrilling follow-up that will get you through the surgery shelf.
Last post we broke down some general principles for approaching the comprehensive (yet loveable) surgery shelf exam. As a quick recap, we focused on:
- the importance of studying whenever able, usually at the hospital
- the material being mostly diagnosis, workup, and treatment/management, with very little operating room knowledge necessary
- the resources that we recommend
- the importance of having a knowledge framework, moving quickly, and going with your intuition
AND, perhaps most importantly
- Using common sense
In this post, we will take things to the next level, diving deeper into some of the actual material that you can expect to see, and what strategies to employ in all sorts of questions.
On the surgery shelf, you can expect a great number of questions involving a patient who was stabbed, shot, or involved in a high-speed motor vehicle crash. For any question (or real life situation) involving a trauma, it is imperative to return to the basics…your ABC’s, the world’s simplest mnemonic for remembering to assess airway, breathing, and circulation, in that order.. Questions will often try to make you think about esoteric imaging studies in a crashing, hypotensive patient. Start by confirming an uncompromised, protected airway. If a patient can answer a question by speaking, you can move on. If they cannot, or their level of consciousness is depressed, do not hesitate to intubate.
‘B’ is for Breathing
This is the time to grab your stethoscope, listen for bilateral breath sounds, and rule out any obvious injuries, like a pneumothorax, tension or otherwise. If you hear both lungs functioning, move on. If there are unilateral absent breath sounds, compromised pre-load/blood pressure, and distended neck veins, it is time to grab that needle for an urgent decompression of the tension pneumothorax.
‘C’ is for Circulation
This is a really common point for intervention, as most of the trauma patients will be hypotensive. It is your job to figure out if the cause of their hypotension. Is it because of blood loss (hypovolemic/hemorrhagic shock)? Have they bled a few liters into the abdomen? Or onto the road/dashboard?
If not, are they in shock because of pump failure (cardiogenic shock)? Big players in your differential here should include myocardial contusion, cardiac tamponade, compressed vena cavae secondary to tension pneumothorax, or an MI. While acute decompensated heart failure could be a cause, in a trauma situation, think about an acute inciting event/injury.
Along these lines, a good rule to live by when answering any “next step in management”: Do not bring a hemodynamically unstable (i.e., crashing) patient to the CT scanner. While a CT can be helpful in diagnosis, an unstable patient needs stabilization, not a protracted diagnostic test. CT’s require wheeling a patient to the scanner, moving them into the machine, having them remain still, and waiting a few minutes for the scan to be complete. While waiting for the scan to complete, no one can do anything else for the patient, and in a trauma situation, that is time wasted. If hemodynamic instability cannot be fixed with proper administration of blood/fluids, then your trauma patient will likely need surgery. That would be an exploratory laparotomy for hemorrhage into the abdomen, or pericardiocentesis/pericardial window for cardiac tamponade.
These are hugely tested and happen a lot in real life. The age-old mnemonic wind, water, walking, wound, wonderdrugs will get you pretty far. Although the word “wonderdrugs” always makes me cringe….
On post-op days (POD) 1-2, think wind, pathologies related to the lungs. These include atelectasis, pneumonia (often secondary to atelectasis), or aspiration. Consider incentive spirometry for primary prevention, and a CXR if you are suspicious.
For POD 3-4, UTI should lead your differential, especially if the patient had an indwelling urinary catheter. Order that urinalysis!
On POD 4-6, deep vein thrombosis and pulmonary embolism (DVT/PE) should come to mind. Depending on the procedure, patients are likely to have experienced endothelial damage to blood vessels and relative immobility (venous stasis), 2 out of 3 components in Virchow’s triad. Think about compression devices, subcutaneous heparin, and WALKING for prevention. If suspicious, consider a venous duplex of the lower extremities or high-resolution CT of the chest w/contrast. If you are really convinced (tachycardic, tachypneic, hypoxic patient with Factor V Leiden on oral contraceptives s/p orthopedic surgery), go straight to IV heparin.
POD 5-7 usually point towards surgical site infections. Check the wound and if it is tender, erythematous, or has purulent discharge, it’s time for antibiotics. Major players include S. aureus, Streptococcus spp., gram-negative rods like Pseudomonas, and anaerobes from the gut. Broad spectrum coverage (including vancomycin for MRSA) should be employed.
After that time-frame, it is time to broaden a differential to include drug fever, or something entirely different that you might be missing. In the 10-14 day mark, abscess formation is a major consideration, and can often be found with ultrasound or CT. And, as with any abscess, incision & drainage (I&D) is the only way to go.
Utilizing Timelines and Demographics
In the heat of the moment, it is too easy to breeze by all the important information in the first sentence of a vignette because you are excited to get to some vital signs, some lab values, and some enticing answer choices. DO NOT miss crucial information like age and timelines in this first sentence. This is incredibly important for Step 2 CK as well. Your 90 year old nursing home patient who is bedbound has a high likelihood to get a pre-renal azotemia because he cannot get up and get a drink. Did that tingling, burning leg pain start instantly 2 hours and 13 minutes ago? If the patient can tell you that, worry about a dreaded arterial embolus. If the same pain started 18 months ago, has gotten progressively worse, and comes on with ambulation, claudication secondary to peripheral artery disease should be on your radar. As sick as you are of hearing it, it all comes back to a good history and physical.
Some last minute advice: While you shouldn’t neglect them, don’t get too hung up on esoteric orthopedic or ENT surgical procedures. The bulk of your test will involve the gastrointestinal, cardiovascular, and respiratory systems. Put in due time in on these big 3 and you will have about half the material covered. It is also important to get (more) comfortable with radiographic findings, all of which are a simple Google Image search away. With a little bit of an understanding of where things are and what pathologies look like, many questions will be way simpler.
That should give you confidence in knowing what to expect on this long and difficult shelf. What questions do you still have about the surgery shelf? Keep them coming and we will be happy to answer and break them down for you!
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