Pearl of the Day: Empyema

Empyema Background - pleural space infection with pus, positive Gram stain/culture, or parapneumonic effusion - predisposing factors: aspiration pneumonia, respiratory disease impairing ciliary function, alcoholism, malignancy, immuncompromise

Causes and Common Organisms - pneumonia -> Streptococcus pneumoniae, Staphylococcus aureus, Haemophilus influenza - lung abscess, esophageal rupture -> mixed oropharyngeal anaerobes - thoracotomy -> Gram-negative bacilli - immunocompromised pneumonia -> tuberculosis, fungal infections - chest trauma -> S. aureus, Gram-negative bacilli - contiguous abdominal infection -> Gram-negative bacilli, anaerobes

Signs/Symptoms - unresolving fever, cough, dyspnea, pleuritic chest pain, malaise - weight loss, night sweats, anemia - decreased tactile fremitus, friction rub, dullness to percussion

Diagnosis - diagnostic criteria: aspiration of grossly purulent material on thoracentesis and at least one of the following: thoracentesis fluid with positive Gram stain or culture, pleural fluid glucose < 40 mg/dL, pH < 7.1, or LDH > 1000 IU/L

Stages of Disease 1. Exudative: <48 hours, free-flowing pleural effusion amenable to chest tube drainage 2. Fibrinopurulent: fibrin strands form in pleural fluid -> loculations; chest tube drainage is unlikely 3. Organizational: several weeks later; extensive fibrosis with "pleural peel" that restricts lung expansion

Treatment - treat underlying cause - definitive treatment: drainage + antibiotics - respiratory or cardiac distress -> thoracentesis - recommended antibiotics: piperacillin/tazobactam 3.375 - 4.5 g IV q6h or imipenem 0.5 - 1 g IV q6h - may add vancomycin for increased risk of MRSA (e.g., patients recently hospitalized, invasive medical device, from long-term healthcare facility, in contact sports, live in unsanitary conditions) - exudative empyema -> chest tube thoracostomy with antibiotics +/- intrapleural fibrinolytic agents if in fibrinopurulent stage - loculated empyema -> video-assisted thoracoscopic surgery - organizational stage -> surgical removal of fibrous peel

Resources Tintinalli's Emergency Medicine, 8th Edition

Pearl of the Day: Periorbital Infections

Periorbital Infections Periorbital Cellulitis - infection of eyelids and periocular tissues anterior to orbital septum - average age: 2 years; most patients < 10 years - spreads from local infection (e.g., conjunctivitis, dacryoadenitis, dacryocystitis, hordeolum), paranasal sinusitis, hematogenous spread from nasopharyngeal pathogens, upper respiratory tract infections - most common pathogens: S. pneumoniae, Streptococcus pyogenes, H. influenzae, Moraxella catarrhalis

Signs/Symptoms - erythematous, tender, swollen, warm eyelid and periorbital area - excessive tearing - no limitation in extraocular muscles, proptosis, pain with eye movement, normal visual acuity - may have difficulty opening eyelid

Management - may require CT scan of orbits to rule out orbital cellulitis - well-appearing, afebrile -> oral antibiotic therapy (e.g., amoxicillin-clavulanate, cephalexin) - severe periorbital cellulitis -> IV antibiotic therapy (e.g., ceftriaxone + vancomycin)

Blepharitis - inflammation of lid margins - anterior blepharitis: inflammation of eyelid where eyelashes attach, usually infectious in nature - posterior belpharitis: inflammation of inner portion of eyelid margin in contact with eye, usually due to dysfunction of meibomian gland - average age: 40 - 50 years - most common etiology: reaction to deltalike toxin from overgrowth of S. epidermidis - symptoms: conjunctival injection, crusting, pruritic eyelids, photophobia, occasionally eye pain - treatment: daily cleansing of edges of eyelids and eyelashes, warm compresses; severe cases require erythromycin or bacitracin-polymyxin ointment

Dacryocele - small bluish-hued palpable mass at nasolacrimal duct without conjunctival erythema or discharge - due to obstruction at valve of Hasner and common canaliculus - treatment: urgent referral to ENT or ophthalmology for possible marsupialization

Dacryoadenitis - inflammation of lacrimal gland - chronic dacryoadenitis is caused by noninfectious inflammatory disorders (e.g., Sjogren's, sarcoidosis, thyroid disesase) - acute dacryoadenitis is usually infectious (from EBV, mumps virus, coxsackievirus, CMV, VZV, S. aureus, streptococci, Neisseria gonorrhea, Chlamydia trachomatis, Brucella melitensis) - viral dacryoadenitis causes less intense discomfort and erythema - treatment: mild infections can be treated with oral first-generation cephalosporin (e.g., cephalexin) or trimethoprim/sulfamethoxazole if MRSA is suspected; severe infections require IV antibiotics (e.g., nafcillin, vancomycin)

Dacryocystitis - inflammation of lacrimal duct or sac usually caused from obstruction - common pathogens:  Streptococcus pneumoniae, staphylococci, Haemophilus influenzae - initial chronic mucopurulent discharge that progresses to erythema and swelling to inframedial eye - usually secondary bacterial infection following viral upper respiratory infection - diagnosis: applying gentle pressure with finger or cotton swab applied to nasolacrimal sac causes reflux of mucopurulent material (should be cultured) - if improperly treated, can lead to periorbital and orbital cellulitis - treatment: usually requires hospital admission with IV antibiotics (e.g., cefuroxime, cefazolin, clindamycin, +/- vancomycin)

Resources Tintinalli's Emergency Medicine, 8th Edition Periorbital Infections, Medscape, https://emedicine.medscape.com/article/798397-overview

Pearl of the Day: Hypomagnesemia

Hypomagnesemia Pathophysiology - second most abundant intracellular cation - acid-base imbalance affects levels of ionized magnesium - may coexist with hypokalemia - essential to many enzymes, including membrane-bound ATPase; metabolism; regulation of PTH secretion - magnesium blocks release of acetylcholine, interferes with release of catecholamines from adrenal medulla - magnesium is absorbed principally in small intestine - associated with hypokalemia due to similar underlying etiologies

Causes - redistribution: IV glucose, IV hyperalimentation, refeeding syndrome, acute pancreatitis, hypoalbuminemia, postparathyroidectomy, osteoblastic metasis - extrarenal losses: lactation, profuse sweating/burns, sepsis, intestinal or biliary fistula, diarrhea - decreased intake: alcoholism, malnutrition, small bowel resection, malabsorption - renal loss: saline or osmotic diuresis, potassium depletion, phosphorus depletion, familial hypophosphatemia, tubulointerstitial renal disease - drugs: loop diuretics, aminoglycosides, amphotericin B, vitamin D intoxication, alcohol, cisplatin, theophylline, PPIs, calcineurin inhibitors - endocrine disorders: SIADH, hyperthyroidism, hyperparathyroidism, hypercalcemic states, hyperaldosteronism

Signs/Symptoms - neuromsucular: tetany, muscle weakness, cerebellar (ataxia, nystagmus, vertigo), confusion, coma, seizures, depression, paresthesias - GI: dysphagia, anorexia - CV: heart failure, dysrhythmias, hypotension, coronary artery vasospasm - hypokalemia, hypocalcemia, anemia - Chvostek and Trousseau signs (traditionally associated with hypocalcemia)

Diagnosis - likely underdiagnosed as levels are rarely drawn - BMP, LFTs, phosphorus, calcium, magnesium, EKG - EKG changes similar to hypokalemia (tachyarrhythmias, afib, torsades de pointes, ventricular tachycardia, ventricular fibrillation) and hypocalcemia  (prolonged QT interval, T wave inversions) due to alteration of intracellular potassium content - enhances digitalis toxicity -> may also contribute to EKG changes - correction for hypoalbuminemia corrected Mg (mmol/L) = measured total Mg + [0.005 x (40 - serum albumin in g/L)] corrected Mg (mEq/L) = measured total Mg x 0.42 + 0.05 x (4 - serum albumin in g/dL)

Treatment - monitor for hypokalemia, hypocalcemia, hypophosphatemia - if asymptomatic, oral magnesium in multiple low doses - for severe and symptomatic, urgent MgSO4 IV replacement - torsades de pointes or eclampsia -> 1 - 4 g or diluted in 100 mL D5 or NS over 10 - 60 min under continuous cardiac monitoring - chronic deficiency -> 6 g MgSO4 per day - chronic alcoholics with delirium tremens -> 8 - 12 g MgSO4 IV on first day (1.5 - 2 g Iv MgSO4 over 1 to 2 hours) - spironolactone maintains magnesium homeostasis and reduces arrhythmias in CHF patients

Resources Tintinalli's Emergency Medicine, 8th Edition