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Diagnosis Deconstructed: An Unembalmed Education

Morchi, Ravi MD

Emergency Medicine News: July 2015 - Volume 37 - Issue 7 - p 3
doi: 10.1097/01.EEM.0000469322.07508.bf
Diagnosis Deconstructed

Dr. Morchiis an associate professor of emergency medicine at UCLA's David Geffen School of Medicine. Read his past columns athttp://bit.ly/MorchiCollection.

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Our patient is unconscious and apneic. Two medical students attempt ventilation: one with a two-handed seal while the other bags. They place a nasal and then oral airway. A chest rise is noted. Time to intubate. Medications are called out followed by multiple attempts with Macintosh and Miller blades.

I take a 21-gauge needle and inject into the peribulbar space. Chemosis ensues. Advancing the needle along the floor of the orbit posteriorly, I inject more and watch the globe proptose. Then, placing the needle through the sclera straight into vitreous, a few milliliters of saline produces an inflated, rock-hard eyeball. I have the students compare the compliance of each globe by palpation over top the edematous conjunctiva and lids that can no longer be manually retracted. They can tell the intraocular pressure is high and the globe proptotic as they perform a lateral canthotomy.

After a dermal wheal and SQ injection at the fifth rib interspace, I ask our participants to use their nondominant hand to completely flatten all soft tissue throughout the procedure. Provided the tissue remains flat and shifted superiorly, a clean incision tract, pleural block, and tube thoracostomy can be accomplished through a 1-cm incision without the need for Kelly guidance of tube placement.

A left anterolateral mini-thoracotomy incision gives us access to the pericardial sac, where I place a 20-gauge angiocath and fill it with saline. Students aspirate from the subxiphoid and parasternal positions while discussing the causes of pericardial tamponade and indications for pericardiocentesis.

Attention is paid to the phrenic nerve as the pericardium is opened and saline tamponade is released. While learners stand out of view, I puncture the RA, RV, and PA sequentially. Upon return, they place their hands around a bloody heart and search for wounds. Once found, serial discharges of a staple gun achieve hemostasis. Internal cardiac compressions are begun. The ET tube is advanced into the right mainstem for left lung deflation in visualizing the posterior mediastinum. I separate the aorta from the esophagus by sharp dissection, and students practice placing a long vascular clamp. We discuss systemic vascular resistance and cephalization of blood flow in states of low cardiac output secondary to hemorrhage.

Extending the thoracotomy incision across the sternum using a Lebsche knife, we incise the inferior pulmonic ligament. Dissecting out the vascular and bronchial hilar structures, we imagine the transit of air in systemic air embolization — from injured bronchi into lacerated pulmonary veins — then practice placing a large Satinsky clamp across the entire hilum.

Proceeding into the superior mediastinum, I isolate the SVC and aortic arch tributaries. We follow the vagus and left recurrent laryngeal nerves. Discussion turns to the causes of a widened mediastinum and the hoarse voice of thoracic aneurysms.

The ET tube is pulled back to tracheal position for left lung ventilation. We watch flattened pulmonary segments reinflate and talk about alveolar recruitment. A midline laparotomy incision allows placement of 1-liter saline bags below the parietal peritoneum into each lower quadrant. Long 18-gauge needles are then used to aspirate bag contents through intact skin, simulating a paracentesis.

Later we explore the entirety of the abdomen with lap sponges and suction. Using bovie electrocautery and ligatures, we remove the gallbladder and skeletonize the portal triad. As structures come into view, we discuss the differential diagnosis of RUQ pain. After reflecting the duodenum medially, participants can visualize and palpate a soft, compliant IVC while hearing about the importance of fluctuations in its caliber for assessing volume status. Before ligating all renal vasculature for a nephrectomy, we discuss pre-renal and intrarenal failure with hands and eyes on the organ. Following the ureter inferiorly in the retroperitoneum, I mention the differential diagnosis for post-renal failure.

We sequentially ligate short gastrics in the LUQ until the splenic hilum. Before the splenectomy, I ask the students for the causes of a splenomegaly. Noting a delicate hilum and soft parenchyma located adjacent to the lower ribs, they can see why the spleen is so commonly injured. I take them into the lesser sac. We dissect loose retroperitoneal tissue around the pancreas and take note of its thin capsule and poor containment of proteolytic enzymes. I pause for a comment on retroperitoneal injury and sequestration of fluid in pancreatitis.

After isolating the esophagogastric junction, performing a subtotal gastrectomy, dividing the pancreas to visualize the confluence of SMV and splenic vein, and dissecting aortic tributaries inferiorly, participants can march from front to back in the differential diagnosis of epigastric pain. Dissection also takes us through the causes of LLQ and RLQ pain.

I ligate the brachiocephalic and external iliac veins bilaterally. Then I place 18-gauge angiocaths to fill the distal vessels with blue-colored saline. The students begin venipuncture attempts using standard landmarks for subclavian and femoral lines. Repeated aspirations make for steadier hands and smoother wire transitions. Peripherally along limbs, they practice nerve blocks, arthrocentesis, and wound repair.

With the thumb and middle finger bracing thyroid cartilage and the index finger feeling for membrane after each swipe of their scalpel, learners attempt a cricothyroidotomy. Later, I place two 0-vicryl sutures through the cricoid cartilage to put the airway on anterior traction. With tension maintained, I note only the posterior component of a single arytenoid visible on laryngoscopy. This looks good to me. Keep tension. Time to practice intubation again. I begin the next lesson: This is a bougie....

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