Grand Rounds Recap 10.02.19

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R1 Clinical Knowledge: Spinal Fractures WITH Dr. Kimmel

Anatomy: When discussing spinal fractures it is helpful to consider the meta-structure of the spinal column in anterior, middle, and posterior portions. The anterior column is bounded by the anterior longitudinal ligament and the anterior portion of the vertebral body, the middle column spans the posterior portion of the vertebral body to the posterior longitudinal ligament, and the posterior column is comprised of all structures beyond that including the pedicles, facets, ligamentum flavum, and the neural arch.

Pathophysiology: A fracture is considered unstable when it affects 2 or more of the structural columns.

Stable vs unstable: Unstable fractures can be easily recalled using the mnemonic device “Jefferson bit off a hangman’s thumb.”

The Jefferson fracture, or C1 burst fracture, involves failure of both the anterior and posterior columns of the spine.

Bilateral cervical facet dislocation occurs generally from a hyperflexion mechanism and often involves a spinal cord injury.

Odontoid fractures are unstable only when the fractured portion lies below the level of the transverse ligament that holds it in place against the C1 arch. Types II and III fall into this category.

Atlanto-occipital dissociation is another hyperflexion injury and may have an associated bran injury.

Hangman’s fractures occur when there are bilateral C2 pedicle fractures resulting from hyperextension.

Teardrop fractures occur as the result of a hyperflexion mechanism that produces a fracture fragment from the anterior portion of a vertebra on the one immediately inferior to it and displaces the body posteriorly. This causes functional disruption of all three columns.

Conversely, the clay-shoveler’s fracture as an example is an isolated fracture of a cervical spinous process. This involves only the posterior column and so is therefore not an unstable fracture.

Spinal precautions: Perhaps somewhat counterintuitively there is a large and growing body of literature to show that spinal precautions are associated with more harm than good. This harm includes introducing difficulty with airway management, increasing midline tenderness, respiratory restriction, increasing ICP, and causing pressure ulcers. EMS agencies in Southwest Ohio use them only under a specific set of circumstances as defined by their protocols and there has been a push recently for switching to vacuum boards with head blocks and traps that conform to patient’s bodies and provide more stability.

Taming the sru: naloxone/heroin-induced pulmonary edema WITH Dr. Koehler

Non-cardiogenic pulmonary edema (NCPE) associated with heroin use was described as early as 1880 by Dr. William Osler long before naloxone was introduced. Until 1953 it carried a grim prognosis as evidenced by the fact that in all the decades since it was first recognized it took until that year for there to be a nonfatal case. It is characterized by persistent hypoxia, characteristic radiographic findings, and frothy sputum.

Naloxone/heroin-induced NCPE affects anywhere from 0.8% - 2.4% of patients who are transported to the hospital for opiate overdoses. Those patients are typically male, have a low prehospital GCS, and are generally novice users. In the vast majority of cases (96%, to be precise) symptoms will be evident within the first one to two hours after presenting.

The pathophysiology of this disease process is not yet well understood. Most cases of naloxone-induced NCPE come from anesthesia literature in patients who were receiving the drug to reverse fentanyl used during their procedures. The mechanism behind the naloxone phenomenon is thought to be due to catecholamine surge brought about by rapid reversal of opiate agonism, an idea that is supported by studies of high-dose naloxone used as a vasopressor in shock.

On the other hand, the heroin-induced phenomenon has several different theories as to its underlying mechanism. This is considered in some ways similar to high-altitude pulmonary edema in that the frothy sputum that is so characteristic has been found to be high in protein and is allowed to accumulate into alveoli due to increased capillary permeability. Histamine may also play a role as well. Another proposed mechanism includes a strong inspiratory effort against a closed glottis.

Treatment for naloxone/heroin NCPE is largely supportive, and fortunately most cases see complete resolution within 24-48 hours. As an adjunctive therapy there does also seem to be some benefit from treating with antihistamines, which lends credence to the histaminergic hypothesis.

Consultant of the quarter: hot topics in trauma WITH dr. pritts

 A hypothetical patient presents as the victim of a high-speed car vs tree MVC with a high shock-index and a positive FAST exam. Where do we stand on choice of resuscitative fluid? On REBOA? On resuscitative thoracotomy?

Resuscitation fluid and Whole Blood: Data supports abandoning the practice of giving large volumes of crystalloid to patients who are expected to need massive transfusion, but blood is a finite resource and it can be difficult to know whether a patient may need massive transfusion.

Fortunately there are validated decision tools that can help us such as the ABC (Assessment of Blood Consumption) score. This scoring system gives one point each to 1) penetrating mechanism, 2) SBP > 90 in the ED, 3) HR > 120 in the ED, and 4) a positive FAST. Two points predicts about a 40% probability of requiring massive transfusion whereas four points on the score predicts a near-100% probability. This scoring system has the benefit of not needing any lab values and can thus be put into use the moment a patient arrives in the ED.

POC INR is also a useful tool as it has been shown that if the value is higher than 1.5 then the patient has an approximate 5-times odds ratio of needing massive transfusion.

The concept of using whole blood as a resuscitation fluid in trauma is not new - it was the fluid of choice in World War I. The practice of fractionating components did not arise until 1940 and gained popularity as a way to increase the shelf-life of a valuable resource. Whereas some components can be stored for only a few days to weeks, plasma can be stored safely for up to one year.

In the early 2000s military physician scientists began to study the benefits of giving ratios of fractionated blood products that more closely matched unfractionated whole blood. The PROMMTT and PROPPR trials are examples of studies that found benefits to giving closely matched proportions of pRBCs, plasma, and platelets. There have since been a number of combat studies that support the use of whole blood as the fluid-of-choice for trauma resuscitation and now at our hospital in Cincinnati our protocol calls for it in all males and all females older than 55 years.

REBOA: The Resuscitative Endovascular Balloon Occlusion of the Aorta procedure and device was first described in the Korean War in a case series of three patients, who all sadly did not survive their injuries. Interest in the device reemerged around 2011 and starting in 2015 there was a dramatic rise in the number of studies looking into its use in civilian trauma.

As it stands, literature is mixed as to whether there is truly a benefit to using REBOA in civilian trauma patients. Studies included in the AORTA registry found benefit, but other studies such as those included in the TQUIP database found the opposite. The discordant results of these studies are likely a symptom of the difficulty in identifying the patient who is truly the most likely to benefit - unfortunately we don’t quite know just who that patient is yet. However, most protocols seem to agree that some combination of traumatic arrest, hemodynamic instability, and lack of response to resuscitation lend towards REBOA use, but that major thoracic hemorrhage, severe upper extremity injuries, and severe TBI are contraindications.

REBOA has several very serious risks including aortic thrombosis, distal limb thrombosis, spinal cord ischemia, aortic or iliac rupture, renal failure, visceral infarction, and ischemia-reperfusion injury that can be anecdotally very impressive. Many of these complications can be mitigated by placing the balloon in zone III between the renal arteries and the aortic bifurcation and by using the newer, smaller 7-french ER-REBOA device.

Resuscitative thoracotomy: Despite all efforts, the sickest trauma patients may still succumb to their injuries even before our very eyes. When this happens we have one final heroic measure to attempt - the resuscitative thoracotomy. Guidelines for performing this procedure are generally that the patient must lose their pulse while in the care of trauma providers, must nonetheless still be considered salvageable, and should have visible cardiac motion or tamponade on ultrasound if available. This is rarely performed for blunt trauma.

The procedure entails entering the chest through an incision in the fifth intercostal space, using a rib spreader to gain access to the mediastinum, making an incision in the pericardium that avoids the phrenic nerve, and delivering the heart through that incision to relieve tamponade, gain source control of bleeding, and performing open cardiac massage. The aorta may also be cross clamped, but this carries with it many of the same risks associated with REBOA.

Hot topics on the horizon:

Rescue foam is an expandable polyurethane foam that can be injected into the abdomen laparoscopically to reduce exsanguination from intra-abdominal trauma and has been shown feasible in porcine models.

Partial REBOA involves intermittent occlusion to achieve sustainable blood pressure but with reduced ischemic complications.

Nano-fibers for non-compressible torso trauma are microscopic fibers that adhere to areas of endothelial injury and may help to achieve hemostasis of injuries that are otherwise anatomically inaccessible.

R1 Clinical diagnostics: Hip and Knee xrays WITH drs. gressick and harty

Hip fractures are common in elderly and osteoporotic patients and are the cause for approximately 300,000 hospitalizations each year. Most are from ground-level falls and they occur twice as frequently in women as in men.

Hip X-rays lack sensitivity. Studies have found that anywhere from 14% to 44% of patients with an initial negative xray were subsequently found to have a fracture on MRI. When a plain film is negative for fracture but clinical suspicion remains high due to factors such as marked tenderness or inability to bear weight despite pain control, consider CT or MRI to investigate for occult fracture. Our radiology department has the ability to perform limited MRI of the pelvis that is fast and will spare radiation if the patient presents at the right time of day.

Knee injuries account for 500,000 emergency department visits each year. They are more common in pediatrics and adolescent patients and are most often traumatic in nature. There are decision support tools such as the Ottawa and Pittsburgh rules that can help us decide if a knee X-ray is indicated. The Ottawa Rule is highly sensitive and accounts for age, palpable tenderness over the head of the fibula or patella, and inability to flex greater than 90 degrees or walk in the ED. The Pittsburgh Rule is less sensitive but is simpler and accounts only for age less than 12 or greater than 55 and inability to take 4 weight-bearing steps in the ED.

Highly morbid knee injuries to bear in mind include dislocation with spontaneous relocation and secondary vascular injury and occult tibial plateau fractures. It is critical to perform a good neurovascular exam on any patient with knee pain. Spontaneous relocation and vascular injury can be detected by decreased pedal pulses or abnormal ABIs in a patient with a suspicious knee injury. Morbid obesity predisposes to this even with low mechanism injuries and if suspected should be pursued with CTA and vascular surgery consultation. If missed they can lead to irreversible limb ischemia and need for above the knee amputation in as little as eight hours after the initial injury.

Tibial plateau fractures can be easily missed on plain films for several reasons. Normal joint surface is projected onto the fracture, which can mask the underlying osseous injury, and osteoporotic fractures can appear normal for weeks after they occur until the plateau flattens. Clues on plain film include a fat fluid level indicative of lipohemarthrosis and xrays should be followed up with CT when the diagnosis is made or when clinical suspicion remains high despite negative xrays.

As a quick-hit side note, remember to obtain sunrise views of the knee if you suspect a patellar injury.

See Dr. Gressick’s full post here

R2 CPC: thyrotoxicosis presenting with a-fib with rvr WITH drs. hassani and lafollette

Thyrotoxicosis affects approximately 1.3% of the population and is far more common in females than it is in males. It presents in different ways depending on the age demographic of the patient - young patients will show many of the classic hyperadrenergic signs that we think of such as hyperactivity, anxiety, heat intolerance, tachycardia, and weight loss. However, older patients can be far more nonspecific. They may have only dyspnea, new onset diabetes or difficulty controlling blood sugar if already diabetic, or heart failure. New onset depression may also be the presenting symptom. As in the case presented by Dr. Hassani, atrial fibrillation with rapid ventricular response may also be the initial presenting sign.

While palpating for an enlarged thyroid gland may be difficult and subjective, our more seasoned faculty members also recommend listening over the thyroid artery with a stethoscope for a superior thyroid artery bruit. The workup should include TSH, which is the most sensitive seromarker, and T3/T4.

Treatment of thyrotoxicosis involves blunting the sympathetic response to increased thyroid hormone with beta blockers (propranolol may also block peripheral conversion of T4 to T3, but atenolol is also commonly used, and esmolol is recommended for the critically ill), stopping new hormone synthesis with PTU or MTZ, and blocking peripheral conversion of hormone with steroids. Iodine is often included in the list of treatments, but is not something that is commonly initiated in the ED.

When patients present with atrial fibrillation know that you can treat this with either a beta blocker or with digoxin. Keep in mind that hyperthyroidism both predisposes to hypercoagulability and can cause a higher rate of metabolism of many medications. Therefore when you start your patient on anticoagulation you will likely need to increase the dose to account for this.

R4 case follow up: Fournier’s gangrene and sepsis-induced cardiomyopathy WITH dr. golden

Fournier’s gangrene affects 1.6 per every 100,000 males, but is exceedingly rare in females. There is a 7.5% associated mortality rate, and the most common co-morbidities include diabetes, morbid obesity, and alcohol use. The disease process is a subtype of necrotizing soft-tissue infections, which are subcategorized into types 1-4 based on their microbiology.

Type 1 NSTI is polymicrobial. These account for over half of cases, are associated with immunocompromised states, and commonly occur on the trunk and perineum. Type 2 are monomicrobial (most often group A Strep) and are associated with trauma or recent surgery. Type 3 NSTI is mostly due to Vibrio species or gram negatives and has a close association with IV drug use, and type 4 NSTI is very rare but is associated with aggressive fungal infections.

The LRINEC score (detailed in an excellent post by our own Dr. Berger can be found here) can help in diagnosis as can obtaining labs and imaging. X-rays have low sensitivity, but CT is much better with sensitivity and specificity of 90 and 93.3%, respectively. There may also be a role for ultrasound in the diagnosis with some studies showing sensitivity of 88% and specificity of 93%. The Fournier’s Gangrene Severity Index is a tool that can help prognosticate the mortality rate of an individual diagnosed.

Early surgical debridement for source control is the mainstay of treatment and delay to surgery over 24 hours has been shown to dramatically increase mortality rate. Medical management should keep in mind the polymicrobial nature of the disease and focus on broad spectrum antibiotics in addition to supportive care. Although the data for clindamycin to reduce toxin formation is controversial, more recent studies have continue to support its use.

Some patients with NSTI or other serious systemic infections may also present with cardiogenic shock. The pathophysiology of sepsis-induced cardiomyopathy is not well understood, but is thought to have contributions from several factors. Patients with underlying CAD who become hypotensive from an overwhelming infection may then decrease their coronary perfusion, leading to a negative feedback loop of hypotension and worsening cardiac function. Low EF in particular is associated with worse outcomes in this disease process. Certain cytokines such as TNFα and IL-1 are thought to play a role, and increased nitric oxide production contributes to vasodilation. The nitric oxide hypothesis is supported by cases in which patients are given methylene blue (a nitric oxide synthase inhibitor) and experience hemodynamic improvement.

Treatment involves addressing the underlying infection, resuscitation with fluids, and supporting hemodynamics with vasopressors and inotropes. The ESMOSEPSIS trial is ongoing and looking at the potential benefit of using beta blockers to improve stroke volume and perfusion, reduce pressor and fluid requirement, shorten hospital and ICU stay, and decrease overall 28-day mortality, but the results are still not yet published.

In cases where there are EKG changes concerning for STEMI, the decision on which problem to intervene upon first can be very difficult. The patient needs both surgical source control of the infection and revascularization of coronary vessels. Delays in either procedure increase morbidity and mortality, but ultimately the decision on how to proceed should be made in close consultation with both interventional cardiology and surgery.