UMEM Educational Pearls

Combination Antimicrobial Therapy for Gram (+) Bacteremia

• Bacteremia is a major cause of morbidity and mortality in the critically ill patient.
• S.aureus remains a common isolate in patients with either hospital-acquired or community-acquired bacteremia.
• In cases of suspected endocarditis due to S.aureus, traditional teaching has been to give an aminoglycoside (i.e. gentamicin) in combination with vancomycin or an antistaphylococcal penicillin.
• Importantly, there is no strong evidence to support this combination in patients with suspected S.aureus bacteremia.
• Furthermore, patients receiving the aminoglycoside combination have higher rates of renal impairment without any added clinical benefit.

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Dabigatran is a new oral anticoagulant (direct thrombin inhibitor) which is being marketed as the new drug to replace warfarin in many cardiac patients. You'll hear much more about it in the coming year, but for now you should know the main advantage and disadvantage:
1. advantage: no need to check levels, e.g. INRs
2. disadvantage: no reversal agent; if a patient is actively bleeding, all you can do is to hold further doses and provide supportive therapy, e.g. tranfusions; hemodialysis is another option, but not ideal to place new dialysis catheters emergently in patients that are coagulopathic!

This second point, the disadvantage of having no reversal agent, is potentially a big issue, especially in older patients at risk for falls. Stay tuned for more information...

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Gout Part 2

• Hyperuricemia can result from both uric acid overproduction (metabolic/myeloproliferative diseases) in addition to uric acid underexcretion (more common).
• Consider gout in any patient who complains of joint pain that reaches peak intensity over hours and may wake them from sleep. Septic joints tend to reach peak intensity of days.
• Patients may have multi joint involvement, low-grade fever and leukocytosis (factors that may lead one to consider an alternative diagnosis)
• Remember that gout is also a disease of the synovial tissue (tendonitis and bursitis).
• NSAIDs: Traditional preferred treatment for acute gout
• Colchicine: Less effective if the current attack is >24 hours. Use correct dosage for best effect/side effect ratio.
• Steroids: At least as effective as NSAIDs.

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Kiwi fruit and latex share several antigens in common.  Thus, individuals who are allergic to either kiwi or latex may also suffer hypersensitivity reactions to the other material.

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• Chemoprophylaxis should be given to those individuals who came into "close contact" with someone infected with meningitis due to meningococcal infection (i.e. Neisseria meningitidis).  It should be given as early as possible following the exposure; when there is a high index of suspicion, do not wait for culture results to give prophylaxis.
• Chemoprophylaxis is generally not indicated when the etiology is Streptococcus pneumoniae, and should be reserved for young children who have not received a Haemophilus influenzae type b (Hib) vaccination and immunocompromised close contacts when the etiology is Hib.
• While the definition of a "close contact" remains somewhat ambiguous, it generally refers to individuals who have had prolonged (>8 hours) contact while in close proximity (<3 ft) to the patient, or who have been directly exposed to the patient's oral secretions between one week prior to the onset of the patient's symptoms until 24 hours after initiation of appropriate antibiotic therapy.
• Standard regimens for antimicrobial prophylaxis include ciprofloxicin, ceftriaxone, and rifampin.  Adults typically require a single oral dose of 500 mg of ciprofloxicin or 250 mg of intramuscular (IM) ceftriaxone, while individuals under age 15 may receive a single dose of 150 mg of IM ceftriaxone.

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Vancomycin is often started empirically for gram-positive and MRSA coverage. Although effective and generally well-tolerated, emerging resistance and side-effect profiles limit its use in some patients. Two alternatives are Linezolid and Daptomycin.

Linezolid

• 600 mg IV every 12 hours
• No renal dosing
• Better lung penetration in pneumonia (compared to Vancomycin)
• Side effects: Serotonin Syndrome (w/ concurrent MAOIs), hypersensitivity reaction, and myelosuppresssion

Daptomycin

• 4 mg/kg IV once daily (skin/subcutaneous tissues infection), 6 mg/kg IV once daily (bacteremia or endocarditis), or 6-8mg/kg IV once daily (bacteremia with intravascular line)
• Renally dosed by altering administration frequency; no change in dose.
• NEVER use for pneumonia; pulmonary surfactant binds and inactivates drug.
• Side effects: Reversible rhabdomyolysis (requires weekly CPK levels)

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Question

60 y/o male transferred from local rehab facility c/o abdominal pain.

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We already know that polypharmacy is a big issue in the elderly, but here are a few key points to keep in mind:
1. Adverse drug effects are responsible for 11% of ED visits in the elderly.
2. Almost 50% of all adverse drug effects in the elderly are accounted for by only 3 drug classes:
     a. oral anticoagulant or antiplatelet agents
     b. antidiabetic agents
     c. agents with narrow therapeutic index (e.g. digoxin and phenytoin)
3. 1/3 of all adverse-effect-induced ED visits are accounted for by warfarin, insulin, and digoxin.
4. Up to 20% of new prescriptions given to elderly ED patients represents a potential drug interaction.

The bottom line here is very simple--scrutinize that medication list and any new prescriptions in the elderly patient!

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Knee dislocations are uncommon, and prosthetic knee dislocations even rarer.  Some general facts about prosthetic knee dislocations are:

• Posterior dislocations typically occur in the post-operative period and are usually the result of trauma that disrupts the PCL ligament.
• Factors that predispose a person to posterior dislocations are valgus deformity of the knee, malposition or improper selection of prosthetic components, patellar instability, and extensor mechanism dysfunction.
• The mechanism for this dislocation is typically flexion and external rotation of the knee when the lateral side of the knee is too loose.
• Anterior dislocations more commonly occur months to years after surgery and usually are not associated with trauma.
• Many of these dislocations result from loss of integrity of the posterior cruciate ligament, which provides anteroposterior stability of the knee and assists in femoral rollback. This motion is essential for the extensor mechanism of the knee to function.
   

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So the magnesium didn't work, and the baby is on the way!  You're prepared with everything you need for the delivery from bulb suction to a tripod for Dad's camera...  But what is going to special about this baby?  

Babies born to mothers who received magnesium therapy for any reason are at risk for hypotonia and severe respiratory depression.

• DO provide respiratory support as needed, as respiratory depression is the only dangerous side effect of hypermagnesemia in the neonate (be prepared to provide supplemental oxygen, positive pressure ventilation (PPV), and possibly intubation)
• DO recognize that generalized hypotonia may be a clue as to how significantly affected the neonate may be, however, don't let the hypotonia itself scare you - it will go away, and is not dangerous in and of itself
• DO follow neonatal resus guidelines (PPV for HR<100, CPR for HR<60), but remember that supportive measures will resolve all problems related to hypermagnesemia in the neonate...if there are other issues, don't blame the mag
• DO NOT give calcium as, in contrast to their mothers, these patients are not hypocalcemic (and the hypermagnesemia will spontaneously resolve in 48 hours)
• DO remember that these infants frequently require a brief NICU stay until they no longer require respiratory support

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·      In the event a nuclear power plant accident, people may be exposed to a mixture of radioactive products. The main radionuclides representing health risk are radioactive caesium and radioactive iodine.

·      Iodine-131 is concentrated in the thyroid gland and may eventually lead to development of thyroid nodules and thyroid cancer.

·      Radioiodine uptake by the thyroid can be blocked by taking potassium iodide (KI) pills or solution, preventing these effects.

·      KI should not be taken in the absence of a clear risk of exposure to a potentially dangerous level of radioactive iodine because KI can cause allergic reactions, skin rashes, salivary gland inflammation, hyperthyroidism or hypothyroidism.

·      Since radioactive iodine decays rapidly, current estimates indicate there will not be a hazardous level of reaching the United States from this accident.

·      There are three FDA approved KI products: Iosat, Thyrosafe and ThyroShield.

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• Trigeminal Neuralgia (TN) presents with unilateral, lancinating head and facial pain, affecting one or more of Cranial Nerve V's divisions.

• The pain occurs in 1 to 5 second multiple attacks throughout the day.  Symptoms may remit and recur.

• TN is associated with trigger points, but lacks any associated focal neurologic deficit or abnormality.

• These characteristics will help distinguish TN from other sources of unilateral headache, such as migraines, cluster headaches, sinusitis, and glaucoma.

• There are a host of treatments for TN, including options such as medical management with anti-convulsants and/or muscle relaxants, surgical ablation, alcohol injection (induces numbness), glycerol injection (destroys affected part of nerve), balloon compression, and administration of electrical current.

• Medical management with analgesics and muscle relaxants is typically the most appropriate, first-line treatment in the emergency department.

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Hemorrhagic bullae in an ill-appearing patient with underlying cirrhosis should prompt consideration for an invasive infection due to Vibrio vulnificus.

V. Vulnificus is a gram negative rod and causes a highly lethal infection in patients with cirrhosis.

Antibiotics for these patients should include coverage for this organism. This should include doxycycline and a third genaration cephalosporin.

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Severe hemolysis/hemolytic anemia in a patient with a prosthetic cardiac valve suggests a paravalvular leak. In this condition, a portion of the valve becomes dislodged from the valve annulus. It can occur immediately after surgery or delayed if from endocarditis. Paravalvular leaks are more common with mechanic valves. Patients may also present with sudden pulmonary edema.

The treatment will focus on management of the pulmonary edema and prompt surgical repair.

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For patients with normal renal function, enoxaparin dosing for treatment of VTE is 1 mg/kg subcut every 12 hours OR 1.5 mg/kg subcut every 24 hours.

Studies have evaluated dosing for patients weighing up to 190 kg and found the 1 mg/kg q 12 hours dose to be safe and effective.  It can even be used for patients heavier than 190 kg, but anti-Xa monitoring is recommended.

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Extravasation from radiocontrast, phenytoin and promethazine have resulted in significant tissue necrosis sometimes requiring surgical debridement and reconstructive plastic surgery. 

Pearl: Keep the infiltrated peripheral IV in and inject hyaluronidase 3-5mL (150U/mL) into the same subcutaneous pocket of medication. Hyaluronidase will increase the systemic absorption of the drug, decreasing its time in the SQ tissue. Extremely safe drug (we have the enzyme in our body) and has been used in neonates as well as adults. Also used for SQ hydration in palliative care and pediatrics.

Controversy: Hot vs Cold - Heat will cause vasodilation and hopefully increase systemic absorption but will likely also increase SQ spread possibly increasing the surface area of injury. Cold will cause vasoconstriction and decrease size of injury however will concentrate drug and possibly worsen the local injury.

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  1: Sokol DK, Dahlmann A, Dunn DW. Hyaluronidase treatment for intravenous  phenytoin extravasation. J Child Neurol. 1998 May;13(5):246-7.     2: Cochran ST, Bomyea K, Kahn M. Treatment of iodinated contrast material  extravasation with hyaluronidase. Acad Radiol. 2002 Aug;9 Suppl 2:S544-6.     3: Few BJ. Hyaluronidase for treating intravenous extravasations. MCN Am J Matern Child Nurs. 1987 Jan-Feb;12(1):23.     4: Kuensting LL. Treatment of intravenous infiltration in a neonate. J Pediatr  Health Care. 2010 May-Jun;24(3):184-8. Epub 2010 Mar 20.     5: Raszka WV Jr, Kueser TK, Smith FR, Bass JW. The use of hyaluronidase in the  treatment of intravenous extravasation injuries. J Perinatol. 1990  Jun;10(2):146-9. 

• Myasthenic patients who initially present in a stable fashion with normal ventilation and minimal dyspnea can decompensate rapidly.
• In Myasthenia Gravis, the body produces antibodies against native post-synaptic acetylcholine (Ach) receptors. Adding a paralytic that occupies the few remaining functional Ach receptors could significantly prolong general muscular dysfunction and the need for ventilatory support during a myasthenic crisis.
• If intubation is required, DO NOT administer neuromuscular blocking/paralytic agents such as succinylcholine or rocuronium, as these agents antagonize Ach binding receptors at the post-synaptic membrane of the neuromuscular junction.
• Studies have shown that the use of propofol and fentanyl, without any paralytic, provides sufficient analgesia and sedation to successfully complete a humane intubation in these cases.
  
   

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Emergency Medicine physicians are gaining experience with non-invasive ventilation (i.e., Bi-level ventilation and continuous positive-pressure ventilation) in managing respiratory distress and failure. Although NIV is commonly used across a variety of pathologies, the best data exists for use with COPD exacerbation and cardiogenic pulmonary edema (CHF, not an acute MI) 

Although other indications for NIV have been studied, the data is less robust (eg., smaller study size, weak control groups, etc.). If there are no contraindications, however, many experts still support a trial of NIV in the following populations:

• Asthma
• Severe community acquired pneumonia
• Acute lung injury / Acute Respiratory Distress Syndrome
• Chest trauma (lung contusion, rib fractures, flail chest,etc)
• Immunosuppression with acute respiratory failure
• Neuromuscular respiratory failure (eg., Myesthenia Gravis)
• Cystic Fibrosis
• Pneumocystis Jiroveci Pneumonia
• “Do not intubate” status

Failure to clinically improve during a NIV trial should prompt invasive mechanical ventilation.

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Question

25 year old male presents after falling from 10 feet and landing on right shoulder. Diagnosis?

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Aortocaval compression occurs often when gestational age is > 20 weeks. This compression significantly compromises the chances of maternal survival in cardiac arrest. Because it is often difficult to know the exact gestational age, it is commonly recommended that emergency C-section in maternal cardiac arrest be performed when the fundus extends above the level of the umbilicus.

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