Episode 66 – Back Pain and Spinal Epidural Abscess

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  • We cover a post from the fantastic St. Emlyn’s team which breaks down a recently published article in Annals of Emergency Medicine comparing diazepam with placebo in patients with acute low back pain.  We recommend you read the full text of the article by Friedman et al.

diazepam

Core Content

We delve into core content on red flags in back pain and spinal epidural abscess using Rosen’s Emergency Medicine and Tintinalli’s Emergency Medicine Chapter 279 as a guide.

red flags

SEA

Rosh Review Emergency Board Review Questions

  • A 13-year-old boy on chemotherapy for acute lymphoblastic leukemia presents with progressive lower back pain for 2 weeks. Per mom, he has had subjective fevers and a “bulge in his lower back” that is warm to touch. He is currently afebrile and has no focal neurologic deficits. An MRI is obtained as seen in the image above. Which of the following regarding this patient’s condition is true?

A. An appropriate antibiotic regimen is cefepime and metronidazole

B. Direct extension of skin and soft tissue infections is the most common cause

C. Erythrocyte sedimentation rate is a sensitive screening tool

D. Most patients present with back pain, fever, and a focal neurologic deficit

Answer

C.  Erythrocyte sedimentation rate is a sensitive screening toolThe patient has a posterior epidural abscess with adjacent osteomyelitis and myositis. The most common cause of an epidural abscess is hematogenous spread of infection, not direct extension from skin or soft tissue infection. Major risk factors include diabetes, intravenous drug abuse, chronic renal failure, alcoholism, and immunosuppression. The most common organism involved is Staphylococcus aureus. Other organisms include streptococci, anaerobes, gram-negative bacilli, and Pseudomonas aeruginosa. Patients present with localized back pain with tenderness to percussion. Fevers are common (reported in up to 75% of patients). MRI is the diagnostic modality of choice, but erythrocyte sedimentation rate is a sensitive marker and may be used in conjunction with plain radiographs to screen for infectious spinal disease.Vancomycin is an important component of the antibiotic regimen because it covers methicillin-resistant Staphylococcus aureus (MRSA) and is usually combined with a 3rd-generation cephalosporin (A). Cefepime is a 4th-generation cephalosporin with pseudomonas coverage. Metronidazole or clindamycin can be added for anaerobic coverage. While the classic triad consists of back pain, fever, and neurologic deficits (D), only a small proportion of patients actually have all three components at presentation. The most common cause of an epidural abscess is hematogenous spread of infection, not direct extension from skin or soft tissue infection (B).

An 8-year-old previously healthy boy presents with back pain and fever for 4 days. He complains of pain in the low back, which is increased with bending or twisting. The pain radiates down into his left leg. He denies trauma. Physical exam is remarkable only for tenderness to palpation over the lumbar spine. What management is indicated

A. Ibuprofen and follow up with his pediatrician

B. MRI of the lumbar spine

C. Plain radiographs of the lumbar spine

D. Urinalysis

Answer

B.

MRI of the lumbar spine. This patient presents with symptoms consistent with discitis and should have an MRI for diagnosis. Discitis is a rare infection of the nucleus pulposus and can involve the cartilaginous endplate and vertebral body. It can occur spontaneously or after surgical procedures. Typically, patients present with severe pain localized to the spinal level of involvement. Any movement of the spine exacerbates the pain. Children often present with sudden onset of back pain and refusal to walk. The lumbar spine is most commonly involved and the average age of patients is 7 years. Radicular symptoms are common (present in 50-90% of cases) and most patients will present with fever (90%). Neurologic deficits are uncommon. Serious pathology should be suspected in any pediatric patient presenting with back pain. Neurologic symptoms are rarely present. MRI is the best study for diagnosis and can also rule out other critical diagnoses including epidural abscess. Laboratory studies are non-specific and insensitive but typically will have an elevated erythrocyte sedimentation rate. White blood cell counts are frequently within the normal range.

Episode 64 – Lumbar Puncture and Central Nervous System Infections

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Ultrasound is gaining popularity in assisting lumbar punctures (LPs). We review this technique as well as Free Open Access Medical Education (FOAM) from the following sites:  5 Min SonoSinai EM, and PEM pearls from ALiEM.

US guided LP

  • This technique is likely most helpful in difficult patients. A recent study demonstrated 27% absolute increase in first attempt success using ultrasound in infants <6 months old undergoing LP; however, the success rate in both arms was abysmal with only 57% success rate in the ultrasound arm.
  • Core Content

We then delve into core content on meningitis, encephalitis, and antiNMDA receptor encephalitis using Rosen’s Chapter 109 and Tintinalli’s Chapters 117 and 174 as a guide.

 Rosh Review Emergency Board Review Questions

A 40-year-old man with HIV presents with two weeks of progressive headache, malaise, and fever. On examination, he has mild nuchal rigidity, confusion, and a temperature of 38.2oC. Cerebrospinal fluid analysis shows a white blood cell count 360 cells/mL with a monocyte predominance, glucose 28 mg/dL, and protein 220 mg/dL. What is the treatment of choice?

A. Acyclovir

B. Amphotericin B

C. Ceftriaxone

D. Vancomycin

Answer

B. Amphotericin B . Cryptococcal meningoencephalitis is an opportunistic infection that occurs primarily in patients with advanced AIDS, although it can be seen in immunocompromised transplant patients as well. The majority of HIV-related cases occur when the CD4 count is < 100 cells/mm3. Patients present with progressive headache, nausea, malaise, and fever over the course of 1 – 2 weeks. Examination findings are typical for meningitis and include altered mental status, photophobia, and fever. Meningismus is less commonly seen. Presentations can be subtle and a high index of suspicion is needed for diagnosis. A CT scan of the brain is indicated if there are signs of increased intracranial pressure or focal neurologic deficits. Lumbar puncture should be performed with careful measurement of the opening pressure. Cerebrospinal fluid will show a mildly elevated white blood cell count with a monocyte predominance, decreased glucose, and mildly elevated protein. However, in some cases the cerebrospinal fluid will only show minor, if any, abnormalities. Cryptococcal antigen testing of the CSF is nearly 100% sensitive and specific. India ink staining will show budding organisms. Treatment of choice is intravenous amphotericin B in addition to oral flucytosine for 14 days followed by an 8 week course of oral fluconazole.  Acyclovir (A) is used in the treatment of herpes meningoencephalitis. Ceftriaxone (C) and vancomycin (D) are indicated in the treatment of bacterial meningitis.

A previously healthy 18-year-old woman presents to the emergency department with complaints of fever, headache, and neck stiffness. She is accompanied by her sister, who expresses concern because the patient seems suddenly confused and cannot remember what she did yesterday. After you administer empiric intravenous antibiotics, which of the following is the next best step?

A. Chest X-ray

B. Complete blood count with differential

C. Lumbar puncture

D. Urinalysis

Answer
C.  Lumbar puncture.  Meningitis is an inflammation of the tissues surrounding the brain and spinal cord (meninges) and may be of infectious (bacterial, viral, or fungal) and various other etiologies. The classic clinical manifestations include nuchal rigidity, fever and altered mental status. Patients often present with headache as well. All patients with suspected meningitis should have lumbar puncture (LP) to evaluate the cerebrospinal fluid (CSF) unless this procedure is contraindicated. There are no absolute contraindications to LP. Relative contraindications include patients with evidence of increased intracranial pressure, thrombocytopenia, bleeding diathesis or spinal epidural abscess. Acute bacterial meningitis is a medical emergency and left untreated or treated late is almost universally fatal. Treatment involves addressing systemic complications and initiating empiric antibiotic therapy as soon as possible.

Up to half of patients with pneumococcal meningitis may have evidence of pneumonia on chest X-ray (A), but this is not part of the initial workup of patients with suspected meningitis. Complete blood count with differential (B) is often ordered in the workup for bacterial meningitis and generally shows increased white blood cell count, but is not as important to order initially as an LP. Urinalysis (D) is generally not a helpful test in the diagnosis of meningitis and therefore not recommended in the workup for patients with suspected bacterial meningitis.

References:

  1. Attia J, Hatala R, Cook DJ, Wong JG. The rational clinical examination. Does this adult patient have acute meningitis?. JAMA. 1999;282(2):175-81.
  2. Nakao JH, Jafri FN, Shah K, Newman DH. Jolt accentuation of headache and other clinical signs: poor predictors of meningitis in adults. Am J Emerg Med. 2014;32(1):24-8.
  3. Neal JT, Kaplan SL, Woodford AL, Desai K, Zorc JJ, Chen AE. The Effect of Bedside Ultrasonographic Skin Marking on Infant Lumbar Puncture Success: A Randomized Controlled Trial. Ann Emerg Med. 2016.

Episode 45 – Diverticulitis

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The Free Open Access Medical Education (FOAM)

Life in the Fast Lane Research and Reviews (LITFL R&R) #121  featured a section on the new American Gastroenterology Association (AGA) guidelines on diverticulitis. The game changer?  Antibiotics aren’t a requirement in select patients with uncomplicated acute diverticulitis [1].

The guidelines based this recommendation on two studies, previously covered by Dr. Ryan Radecki on Emergency Medicine literature of note over the past 3 years. This post details a prospective observational study on antibiotics for acute diverticulitis [2].  In another post, Dr. Radecki discusses an RCT of antibiotics (ABX) vs IV fluids only.

  • 623 patients with an episode with a short history and with clinical signs of diverticulitis, with fever (>38 Celsius) and inflammatory parameters, verified by computed tomography (CT), and without any sign of complications (fistula, perforation, abscess) or signs of sepsis
  • Randomized to IVF only or IVF + antibiotics
  • Primary Outcome – 6 patients (1.9%) developed complications in the no ABX arm vs 3 patients (1.0%) in the ABX arm (not statistically significant). Overall study complication rate was 1.4% [3].

Of note, since 2012, the Cochrane Review suggests that antibiotics may not be necessary in uncomplicated appendicitis [4].

A note on LITFL R&R – every week this blog post features 5-10 high yield articles, culled from contributors across the globe from all kinds of literature – pediatrics, critical care, emergency medicine, etc. It is difficult to keep up with the literature and some have estimated that the number needed to read (NNR) to of 20-200, depending on the journal [5].  Those looking for high yield articles may find their time well spent focused on this cherry picked selection of articles.

Core Content

We delve into core content on diverticula and clostridium difficile using Rosen’s Medicine (8e),  Chapters 31, 173 and Tintinalli’s Emergency Medicine: A Comprehensive Study Guide  (7e) Chapters 76, 85.

Diverticulosis

Diverticula are small herniations through the wall of the colon (small outpouchings). Often this is asymptomatic, identified incidentally on imaging or colonoscopy. Most common cause of lower gastrointestinal bleeding (LGIB) in adults in the U.S.

Diverticulitis

Diverticulitis Algorithm
Diverticulitis Algorithm

Clostridium Difficile (c. diff)

C. Difficile

 

Note on testing – asymptomatic carriage rates of c.diff vary based on the population but may be between 3-50%.  Textbooks quote a 3% carriage rate in newborns and rates of 20%-50% in hospitals and long term care facilities, respectively [10,11].

C. diff historically has a unique odor, refrains of “it smells like c. diff” echo in the halls.  Yet this does not perform very well, essentially a coin flip based on a 2013 study by  Rao and colleagues.  They  had 18 nurses smell 10 stool samples (5 c. diff positive and 5 c. diff neg) and found the median percent correct identification of c. diff positive vs negative was 45% [6]. 

Rosh Review Questions

Question 1. [polldaddy poll=9330955]

Question 2.A 75-year-old woman presents with several days of voluminous watery stools. She was discharged from the hospital one week ago following treatment for pneumonia. Stool studies reveal C. difficile toxin. [polldaddy poll=9333580]

Answers:

  1. C. Patients who present with uncomplicated diverticulitis should be treated with oral antibiotics for 7-10 days. Diverticulitis is an inflammation of the diverticulum in the large intestine. In uncomplicated cases of diverticulitis, patients present with abdominal pain typically in the left lower quadrant with tenderness to palpation in the same area. Patients should not have peritoneal signs or masses on examination. Complicated diverticulitis is defined as the presence of either extensive inflammation or complications such as abscess, peritonitis or obstruction. Patients with uncomplicated diverticulitis can be empirically treated with antibiotics (typically as an outpatient) for 7-10 days. Patients with uncomplicated diverticulitis typically do not require CT imaging (A). Patients with complicated diverticulitis should be treated with intravenous antibiotics (B) and admitted to the hospital. Ultrasound (D) has shown promise in diagnosing diverticulitis but CT is the imaging modality of choice.
  2. C.C. difficile infection is caused by a spore-forming obligate anaerobic bacillus that causes a spectrum of disease ranging from diarrhea to pseudomembranous colitis. C. difficile is the most common cause of infectious diarrhea in hospitalized patients in the United States. Risk factors for infection include broad-spectrum antibiotic use, particularly clindamycin, though other antibiotics have also been implicated. Additional risk factors include prolonged hospitalization, advanced age, and underlying comorbidities. The spectrum of clinical manifestations includes frequent watery stools to a more toxic clinical presentation with profuse stools (up to 20-30 per day), crampy abdominal pain, fever, leukocytosis, and hypovolemia. C. difficile colitis should be suspected in patients who develop diarrhea while taking or after recent cessation of antibiotics, or among recently discharged patients who develop diarrhea. Diagnosis is confirmed by identification of C.difficile toxin in the stool. Colonoscopy, while not usually necessary for diagnosis, reveals characteristic yellowish plaques in the intestinal lumen, confirming pseudomembranous colitis. Treatment for C. difficile infection depends on disease severity. Previously healthy patients with very mild symptoms may be managed by cessation of the offending antibiotic and close clinical monitoring. Oral metronidazole, 500 mg po every 6 hours for 10-14 days is the treatment for moderately severe colitis. Severely ill patients should be hospitalized and treated with oral vancomycin, 125 mg po every 6 hours for 10-14 days.

References:

  1. Stollman N, Smalley W, Hirano I, AGA Institute Clinical Guidelines Committee. American Gastroenterological Association Institute Guideline on the Management of Acute Diverticulitis. Gastroenterology. 2015;149(7):1944–9. doi:10.1053/j.gastro.2015.10.003.
  2. Isacson D, Thorisson A, Andreasson K, Nikberg M, Smedh K, Chabok A. Outpatient, non-antibiotic management in acute uncomplicated diverticulitis: a prospective study. Int J Colorectal Dis. 2015;30(9):1229–1234. doi:10.1007/s00384-015-2258-y.
  3. Chabok A, Phlman L, Hjern F, Haapaniemi S, Smedh K. Randomized clinical trial of antibiotics in acute uncomplicated diverticulitis. Br J Surg. 2012;99(4):532–539. doi:10.1002/bjs.8688.
  4. Shabanzadeh DM1, Wille-Jørgensen P.Antibiotics for uncomplicated diverticulitis.  Cochrane Database Syst Rev. 2012 Nov 14;11:CD009092. doi: 10.1002/14651858.CD009092.pub2. 
  5. McKibbon KA, Wilczynski NL, Haynes RB. What do evidence-based secondary journals tell us about the publication of clinically important articles in primary care journals? BMC Med. 2004;2:33.
  6. Rao K, Berland D, Young C, Walk ST, Newton DW. The Nose Knows Not: Poor Predictive Value of Stool Sample Odor for Detection of Clostridium difficile. Clinical Infectious Diseases. 56(4):615-616. 2012.
  7. “Chapter 85: Diverticulitis.” Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e.New York, NY: McGraw-Hill; 2011. p 578-581.
  8. “Disorders of the Large Intestine.” Rosen’s Emergency Medicine, 8th e. p 1261-1275.
  9. “Gastrointestinal Bleeding.”  Rosen’s Emergency Medicine, 8th e. p 248-253.
  10.  “Infectious Diarrheal Disease and Dehydration.” Rosen’s Emergency Medicine, 8th ep 2188-2204.
  11. “Chapter 76: Disorders Presenting Primarily with Diarrhea.” Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e.New York, NY: McGraw-Hill; 2011. p 534-535
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Sepsis: Redefined

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The Society of Critical Care Medicine (SCCM)  and the European Society of Intensive Care Medicine (ESICM) redefined sepsis with the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). Sepsis is life-threatening organ dysfunction due to dysregulated host responses to infection.  Septic shock is a subset of sepsis where underlying circulatory and cellular/metabolic abnormalities are profound enough to substantially increase mortality [2]. 

2003 vs 2016 Definitions of Sepsis [1-4]

Sepsis 3.0

Systemic Inflammatory Response Syndrome (SIRS) is out.  

  • Includes normal responses to infection (eg. fever and tachycardia is not dysregulated infection; it’s just infection)
  • SIRS even MISSES up to ⅛ very septic ICU pts (NEJM 2015) [5]. 

qSOFA is in. a qSOFA score of 2 or 3 or a rise in the SOFA score of 2.  The SOFA score requires a ton of lab values so the authors wanted something that could be assessed at triage, hence the quick SOFA score (qSOFA). The authors derived and retrospectively validated this score and compared it to SIRS in a cohort of 148,907 patients [3]

qSOFA scoring
qSOFA scoring   —@FOAMpodcast

Issues:

  • Unclear how to interpret studies (EGDT through ProCESS, PROMISE, ARISE) with new definitions.
  • CMS is not going to adapt.
  • Not endorsed by ACEP or SAEM as emergency providers were not included.
  • qSOFA has not been prospectively validated. It’s unclear how it will perform in this fashion

Notes: Sepsis rates have increased over the past 10 years and it appears that mortality has decreased.  However, less sick patients are included  in this. It appears that the Sepsis 3 authors were hoping for a more specific definition.

References:

  1. Levy MM, Fink MP, Marshall JC. 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis Definitions Conference. Critical care medicine. 31(4):1250-6. 2003.
  2.  Singer M, Deutschman CS, Seymour CW, et al: The Sepsis Definitions Task Force The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3).
    AMA. 2016;315(8):801-810. doi:10.1001/jama.2016.0287.
  3.  Seymour CW, Liu V, Iwashyna TJ, et al. Assessment of clinical criteria for sepsis: For the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3).JAMA. 2016;315(8):762-774. doi:10.1001/jama.2016.0288.
  4. Shankar-Hari M, Phillips G, Levy ML, et al.Developing a New Definition and Assessing New Clinical Criteria for Septic ShockFor the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) (JAMA, Feb 22, 2016).
  5. Kaukonen KM, Bailey M, Bellomo R. Systemic Inflammatory Response Syndrome Criteria for Severe Sepsis. The New England journal of medicine. 373(9):881. 2015.
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Episode 25 – Skin and Skin Structure Infections

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The Free Open Access Medical Education (FOAM)

We review the post by Bryan Hayes, PharmD, FAACT on Academic Life in Emergency Medicine,  Sulfamethoxazole-Trimethoprim for Skin and Soft Tissue Infections: 1 or 2 Tablets BID?

The Take Home: Most abscesses do not need antibiotics after incision and drainage.  If the patient has systemic signs (fever, tachycardia), co-morbidities, or a concurrent cellulitis, they may need antibiotics.  Sulfamethoxazole-trimethoprim (SMX-TMP / Bactrim) is one of the most commonly used agents in this case, as it covers MRSA.

Dosing: Two double strength (DS) tablets twice daily is a commonly prescribed regimen; yet,1 DS tablet twice daily is sufficient in most cases with exceptions for patients >100 kg, immunocompromised, or in trauma [1]. ; however, this increases the likelihood of adverse events (nausea, hyperkalemia) without notable substantial positive return.

The Bread and Butter

We cover cellulitis and abscesses, necrotizing infections, and Erythema Multiforme/Stevens-Johnson Syndrome/Toxic Epidermal necrolysis using Tintinalli (7e) Chapter; Rosen’s (8e) Chapter 137 as well as the IDSA guidelines.  But, don’t just take our word for it.  Go enrich your fundamental understanding yourself.

Cellulitis/Abscess

Non-purulent – cover for strep (penicillin, cephalexin/cefazolin).  Even in areas with high incidences of community MRSA, the recommendations for non-purulent skin infections is strep coverage. Five days of treatment is probably enough, and IDSA and Rosenalli approved (see this post)

Purulent – Incise & Drain (I&D).  Cover for MRSA in patients that failed initial I&D or those with systemic signs.

Adapted from the 2014 IDSA Guidelines

Necrotizing Infections

Presentation – pain out of proportion to exam findings, abnormal tachycardia (particularly out of proportion to degree of fever). Crepitus is not reliable (present in 13-30% of patients).

Diagnosis – clinical. X-rays, CT, and MRI have all been used but both x-rays and CT lack sensitivity and it’s probably not a good idea to send a sick patient to MRI.  The gold standard diagnosis is operative findings.

  • The LRINEC score was derived to aid in diagnosis using lab values (sodium, creatinine, white blood cell count, hemoglobin, glucose, CRP) but has not been sufficiently predictive in validation attempts [10].

Classification

  • Type I – polymicrobial. Common in diabetics, immunocompromised.
  • Type II – monomicrobial (often Group A strep or clostridia).
  • Type III? – vibrio, but apparently this is controversial.

Treatment

  • Intravenous fluid and general resuscitation, surgical consult, and antibiotics.

Erythema Multiforme/Stevens-Johnson/Toxic Epidermal Necrolysis (for more, see this Hippo EM podcast)

Courtesy of Rosh Review
Courtesy of Rosh Review

Medications most associated with SJS/TEN:  Antibiotics (sulfa), Anti-epileptics, Nonsteroidals

Treatment of SJS/TEN:  Fluid resuscitation, Burn Center/ICU care, and IVIG

Generously Donated Rosh Review Questions 

Question 1. A 22-year-old woman presents to the emergency department with a painful rash. She has had several days of malaise, arthralgias, and low-grade fever, and today developed diffuse painful erythema across her body which is beginning to blister. She takes no medications, but reports completing a course of trimethroprim-sulfamethoxazole one week ago for a urinary tract infection. Examination reveals diffuse tender erythema over her trunk and extremities with multiple ill-defined large bullae, some of which have ruptured, leaving large areas of denuded skin behind. Oral ulcerations are also noted. [polldaddy poll=8689023]

Question 2.  A 54-year-old man with diabetes presents with severe leg pain. The pain has worsened over the last two days with increased swelling of the calf. He has no chest pain or shortness of breath. Vital signs are: T 101.8°F, BP 98/62, HR 118, RR 18. Physical examination is notable for erythema of the calf, mild tenderness, and crepitus. You initiate IV fluids and broad-spectrum antibiotics. [polldaddy poll=8689082]

Answers

1. This patient has toxic epidermal necrolysis (TEN). TEN is an acute inflammatory process characterized by tender erythema, painful bullae formation, and subsequent exfoliation. It often begins with prodromal symptoms such as fever, malaise, and myalgias. TEN is considered a dermatologic emergency and patients may appear toxic on presentation. Medications (within the first few months of administration) are the most common cause, with sulfa and penicillin antibiotics, anticonvulsants, and oxicam non-steroidal anti-inflammatory drugs commonly implicated. Management of TEN involves admission to a burn unit, fluid resuscitation, and prevention of secondary infection. Steroids are not an indicated treatment. Staphylococcal scalded skin syndrome (C) occurs primarily in infants and young children. Infection with exotoxin-producing Staphyloccus aureus leads to diffuse erythroderma and subsequent exfoliation. Mucous membranes are not usually involved. Treatment is fluid resuscitation and antibiotics. Infection with HSV-1 and HSV-2 results in localized skin infection, though in patients with underlying immunosuppression or malignancy it may lead to disseminated herpes simplex virus infection (A), characterized by diffuse vesicles and ulcerations and multisystem involvement. Photosensitive drug reactions (B) are characterized by confluent erythema, macules, papules, or sometimes vesicles in sun-exposed areas such as the face, neck, and arms, occurring within 1-3 weeks of the patient taking an offending agent.  Medications commonly associated with photosensitivity include sulfonamides, thiazides, furosemide, and fluoroquinolones

2. Necrotizing fasciitis is an infection of the subcutaneous tissue that spreads rapidly across the fascial planes and is often fatal even with aggressive treatment. Risk factors for necrotizing infections include diabetes, vascular insufficiency, and immunosuppression. Classically patients have pain out of proportion to examination. Later findings include diffuse swelling, erythema, induration and crepitus. The gold standard for diagnosis is direct visualization in the operating room by a surgeon. Surgeons may elect to perform a bedside biopsy prior to full exploration. Management includes aggressive IV hydration, broad-spectrum antibiotics, and surgical debridement. CT scan with intravenous contrast of the lower extremity (A) may demonstrate findings suggestive of a necrotizing infection including subcutaneous gas, stranding along the fascial planes or fluid collection. However, the negative predictive value of CT scan has not been quantified and is not yet considered the gold standard. Doppler ultrasound of the lower extremity (B) may be helpful in identifying venous thrombosis as a cause of edema and fullness of the leg. Additionally, sonography may visualize an area of deep fluid collection and may demonstrate artifact from a significant amount of subcutaneous air if present. Measurement of serum lactate and CPK (C) is helpful when positive but not sensitive enough to rule out the diagnosis of necrotizing fasciitis. The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) incorporates other laboratory markers (CRP, WBC, Hemoglobin, Sodium, Creatinine, Glucose) into a decision-rule however lacks sufficient sensitivity in larger studies.

References

1.Stevens DL, Bisno a. L, Chambers HF, et al. Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2014.

2.  Shehab N1, Patel PR, Srinivasan A, Budnitz DS. Emergency department visits for antibiotic-associated adverse events. Clin Infect Dis. 2008 Sep 15;47(6):735-43.

3.  Bourgois FT, Mandl KD, Valim C et al.  Pediatric Adverse Drug Events in the Outpatient Setting: An 11-Year National Analysis. Pediatrics. Oct 2009; 124(4): e744–e750.
4. Goldman JL, Jackson MA, Herigon JC et al.  Trends in Adverse Reactions to Trimethoprim-Sulfamethoxazole.  Pediatrics. Jan 2013; 131(1): e103–e108.

5. Khow KS, Yong TY. Hyponatraemia associated with trimethoprim use. Curr Drug Saf. 2014;9:(1)79-82. [pubmed]

6.Antoniou T, Hollands S, Macdonald EM, et al. Trimethoprim-sulfamethoxazole and risk of sudden death among patients taking spironolactone. CMAJ. 2015.

7. Hepburn MJ, et al. Comparison of short-course (5 days) and standard (10 days) treatment for uncomplicated cellulitis.  Arch Intern med 2004; 164, 1669-1674

8. Hurley HJ, Knepper BC, Price CS, et al. Avoidable antibiotic exposure for uncomplicated skin and soft tissue infections in the ambulatory care setting. Am J Med. 2013;126(12):1099–106.

9. Pallin DJ, Binder WD, Allen MB et al.  Clinical Trial: Comparative Effectiveness of Cephalexin Plus Trimethoprim-Sulfamethoxazole Versus Cephalexin Alone for Treatment of Uncomplicated Cellulitis: A Randomized Controlled Trial.  Clin Infect Dis. (2013) 56 (12): 1754-1762.

10.Liao CI, Lee YK, Su YC et al. Validation of the laboratory risk indicator for necrotizing fasciitis (LRINEC) score for early diagnosis of necrotizing fasciitis. Tzu Chi Medical Journal (2012) 24(2):73-76

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Episode 22 – The Knee

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The Free Open Access Medical Education (FOAM)

This week we’re covering a post from the incredible pediatric resource, Don’t Forget the Bubbles, “Knee X-ray Interpretation” by Dr. Tessa Davis.  We use a systematic approach to assessing chest x-rays, so why not knee x-rays?

  •  Know the anatomy
  •  Look at:
    • Effusion
    • Main bones
    • Tibiofemoral alignment
    • Tibial plateaus
    • Intercondylar eminence
    • Patellar tendon disruption
    • Patellar fracture

The Bread and Butter

We summarize some key topics from Rosenalli, that’s Tintinalli (7e) Chapter s271, 281; Rosen’s (8e) Chapters 57, 136.  But, don’t just take our word for it.  Go enrich your fundamental understanding yourself.

Knee Dislocation

  • Anterior is most common (40%), posterior (33%)
  • Approximately 50% of knee dislocations may be relocated upon presentation to the hospital (this does not reduce risk of badness)
  • Most worrisome sequelae = popliteal artery disruption.  Of patients with popliteal disruption, the amputation rate rises to 90% 8 hours after the injury without surgical intervention.
  • Workup may depend on your institution (ex: angiogram vs. CT angio vs. ultrasound) but all patients will need an ABI + 24 hour of pulse checks per current standards.
Screen Shot 2015-01-08 at 1.10.48 PM
Algorithm (adopted from Rosen’s)

Septic Arthritis

  • Most Common Organisms: S. aureus, N. gonorrhea
  • Hematogenous spread
  • Most Common Location: knee, hip

Risk factors such as immunocompromised hosts and use of steroids are risk factors for septic arthritis but the ones with the highest likelihood ratio (LR+ >10 is ideal):

  • Skin infection overlying prosthetic joint (LR+ 15)
  • Joint surgery within the preceding 3 months (LR+ 6.9)
  • Age > 80 (LR+ 3.5)

Diagnosis:  In the red, hot, swollen, painful joint, think septic arthritis.  Clinical and laboratory indicators aren’t great. Synovial fluid analysis, particularly the culture exists as the gold standard.  Arthrocentesis Trick of the Trade from ALiEM. Here are the operating characteristics from Margaretten et al:

  • Fever: Sensitivity 57%
  • Lab tests: White Blood Cell count (WBC), sedimentation rate (ESR), and c-reactive protein don’t perform well
    • WBC LR+  1.4 (1.1-1.8); LR- 0.28 (0.07-1.10)
    • Erythrocyte sedimentation rate 1.3 (1.1-1.8); LR- 0.17 (0.20-1.30)
    • C-reactive protein  1.6 (1.1-2.5); LR- 0.44 (0.24-0.82)
  • Synovial fluid gram stain and culture is the “gold standard.”

Treatment: Intravenous antibiotics and washout of the joint by orthopedics in the operating room

 Generously Donated Rosh Review Questions 

Question 1. A 67-year-old man with a history of gout presents with atraumatic left knee pain. Physical examination reveals an effusion with overlying warmth and erythema. There is pain with passive range of motion. He reports a history of gout in this joint in the past. [polldaddy poll=8568492]

Question 2.  A 27-year-old woman presents with severe left knee pain after an MVC where she was the front passenger. She states her knee hit the dashboard. An X-ray of the patient’s knee is shown below. After reduction, the physical examination reveals swelling of the knee and an Ankle-Brachial Index (ABI) of 0.8. [polldaddy poll=8569540]

Screen Shot 2015-01-12 at 5.13.06 PM

Answers.

1. D. Septic arthritis is a bacterial or fungal infection of a joint typically spread hematogenously unless there is direct bacterial contamination. The synovium is highly vascular and lacks a basement membrane making it susceptible to bacterial seeding. Certain conditions predispose individuals to septic arthritis including diabetes, sickle cell disease, immunocompromise, alcoholism or pre-existing joint disease like rheumatoid arthritis or gout. Fever is present in less than half of cases of septic arthritis so with clinical suspicion an arthrocentesis is indicated. The knee is the most common joint affected and patients have pain (especially on passive range of motion) and decreased range of motion often accompanied by warmth, erythema and fever. This patient may have an acute gouty flare, but the clinician must exclude an infection. On joint fluid analysis, the white blood cell count of a septic joint is typically > 50,000. Indomethacin (B) is a non-steroidal anti-inflammatory agent commonly used in the treatment of acute gout. Gout is an arthritis caused by deposition of monosodium urate monohydrate crystals in the joint space. Acute flares involve a monoarticular arthritis with a red, hot, swollen and tender joint. Acute episodes of gout result from overproduction or decreased secretion of uric acid. However, measurement of serum uric acid (C) does not correlate with the presence of absence of an acute flare. A radiograph of the knee (D) may show chronic degenerative changes associated with gout but will not help to differentiate a gouty arthritis versus septic arthritis.

2. C. Obtain Angiography. This patient presents with a knee dislocation and signs of a popliteal artery injury requiring angiography for diagnosis. A knee dislocation refers to a dislocation of the tibia in relation to the femur and not a patellofemoral dislocation. A tibiofemoral dislocation is a limb-threatening emergency due to the high rate of popliteal artery injury. The neurovascular bundle (popliteal artery, popliteal vein and common peroneal nerve) runs posteriorly in the popliteal fossa. The popliteal artery is tethered to the femur and tibia by a fibrous tunnel and is inherently immobile making it susceptible to injury during dislocation. Knee dislocations typically occur in major trauma. An MVC where the knee strikes the dashboard is a common scenario. The dislocation is usually clinically obvious and should be emergently reduced regardless of the presence of confirmatory X-rays. The leg should rapidly be assessed for any “hard” signs of vascular injury including an absence of pulse, limb ischemia, rapidly expanding hematoma, the presence of a bruit or thrill and pulsatile bleeding. Neurologic status should also be assessed prior to and after reduction. After reduction, all patients should have ankle-brachial index (ABI) performed. A normal ABI is > 0.9. Any patient with an ABI less than this should be further investigated for a popliteal injury with angiography. Splint and elevation (D) may be appropriate once a vascular injury is ruled out. The patient should not be discharged home (A) with an abnormal ABI. Observation and repeat ABI (B) is indicated if the initial ABI is normal.

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Episode 22 – The Knee

(ITUNES OR LISTEN HERE)

The Free Open Access Medical Education (FOAM)

This week we’re covering a post from the incredible pediatric resource, Don’t Forget the Bubbles, “Knee X-ray Interpretation” by Dr. Tessa Davis.  We use a systematic approach to assessing chest x-rays, so why not knee x-rays?

  •  Know the anatomy
  •  Look at:
    • Effusion
    • Main bones
    • Tibiofemoral alignment
    • Tibial plateaus
    • Intercondylar eminence
    • Patellar tendon disruption
    • Patellar fracture

The Bread and Butter

We summarize some key topics from Rosenalli, that’s Tintinalli (7e) Chapter s271, 281; Rosen’s (8e) Chapters 57, 136.  But, don’t just take our word for it.  Go enrich your fundamental understanding yourself.

Knee Dislocation

  • Anterior is most common (40%), posterior (33%)
  • Approximately 50% of knee dislocations may be relocated upon presentation to the hospital (this does not reduce risk of badness)
  • Most worrisome sequelae = popliteal artery disruption.  Of patients with popliteal disruption, the amputation rate rises to 90% 8 hours after the injury without surgical intervention.
  • Workup may depend on your institution (ex: angiogram vs. CT angio vs. ultrasound) but all patients will need an ABI + 24 hour of pulse checks per current standards.
Screen Shot 2015-01-08 at 1.10.48 PM
Algorithm (adopted from Rosen’s)

Septic Arthritis

  • Most Common Organisms: S. aureus, N. gonorrhea
  • Hematogenous spread
  • Most Common Location: knee, hip

Risk factors such as immunocompromised hosts and use of steroids are risk factors for septic arthritis but the ones with the highest likelihood ratio (LR+ >10 is ideal):

  • Skin infection overlying prosthetic joint (LR+ 15)
  • Joint surgery within the preceding 3 months (LR+ 6.9)
  • Age > 80 (LR+ 3.5)

Diagnosis:  In the red, hot, swollen, painful joint, think septic arthritis.  Clinical and laboratory indicators aren’t great. Synovial fluid analysis, particularly the culture exists as the gold standard.  Arthrocentesis Trick of the Trade from ALiEM. Here are the operating characteristics from Margaretten et al:

  • Fever: Sensitivity 57%
  • Lab tests: White Blood Cell count (WBC), sedimentation rate (ESR), and c-reactive protein don’t perform well
    • WBC LR+  1.4 (1.1-1.8); LR- 0.28 (0.07-1.10)
    • Erythrocyte sedimentation rate 1.3 (1.1-1.8); LR- 0.17 (0.20-1.30)
    • C-reactive protein  1.6 (1.1-2.5); LR- 0.44 (0.24-0.82)
  • Synovial fluid gram stain and culture is the “gold standard.”

Treatment: Intravenous antibiotics and washout of the joint by orthopedics in the operating room

 Generously Donated Rosh Review Questions 

Question 1. A 67-year-old man with a history of gout presents with atraumatic left knee pain. Physical examination reveals an effusion with overlying warmth and erythema. There is pain with passive range of motion. He reports a history of gout in this joint in the past. [polldaddy poll=8568492]

Question 2.  A 27-year-old woman presents with severe left knee pain after an MVC where she was the front passenger. She states her knee hit the dashboard. An X-ray of the patient’s knee is shown below. After reduction, the physical examination reveals swelling of the knee and an Ankle-Brachial Index (ABI) of 0.8. [polldaddy poll=8569540]

Screen Shot 2015-01-12 at 5.13.06 PM

Answers.

1. D. Septic arthritis is a bacterial or fungal infection of a joint typically spread hematogenously unless there is direct bacterial contamination. The synovium is highly vascular and lacks a basement membrane making it susceptible to bacterial seeding. Certain conditions predispose individuals to septic arthritis including diabetes, sickle cell disease, immunocompromise, alcoholism or pre-existing joint disease like rheumatoid arthritis or gout. Fever is present in less than half of cases of septic arthritis so with clinical suspicion an arthrocentesis is indicated. The knee is the most common joint affected and patients have pain (especially on passive range of motion) and decreased range of motion often accompanied by warmth, erythema and fever. This patient may have an acute gouty flare, but the clinician must exclude an infection. On joint fluid analysis, the white blood cell count of a septic joint is typically > 50,000. Indomethacin (B) is a non-steroidal anti-inflammatory agent commonly used in the treatment of acute gout. Gout is an arthritis caused by deposition of monosodium urate monohydrate crystals in the joint space. Acute flares involve a monoarticular arthritis with a red, hot, swollen and tender joint. Acute episodes of gout result from overproduction or decreased secretion of uric acid. However, measurement of serum uric acid (C) does not correlate with the presence of absence of an acute flare. A radiograph of the knee (D) may show chronic degenerative changes associated with gout but will not help to differentiate a gouty arthritis versus septic arthritis.

2. C. Obtain Angiography. This patient presents with a knee dislocation and signs of a popliteal artery injury requiring angiography for diagnosis. A knee dislocation refers to a dislocation of the tibia in relation to the femur and not a patellofemoral dislocation. A tibiofemoral dislocation is a limb-threatening emergency due to the high rate of popliteal artery injury. The neurovascular bundle (popliteal artery, popliteal vein and common peroneal nerve) runs posteriorly in the popliteal fossa. The popliteal artery is tethered to the femur and tibia by a fibrous tunnel and is inherently immobile making it susceptible to injury during dislocation. Knee dislocations typically occur in major trauma. An MVC where the knee strikes the dashboard is a common scenario. The dislocation is usually clinically obvious and should be emergently reduced regardless of the presence of confirmatory X-rays. The leg should rapidly be assessed for any “hard” signs of vascular injury including an absence of pulse, limb ischemia, rapidly expanding hematoma, the presence of a bruit or thrill and pulsatile bleeding. Neurologic status should also be assessed prior to and after reduction. After reduction, all patients should have ankle-brachial index (ABI) performed. A normal ABI is > 0.9. Any patient with an ABI less than this should be further investigated for a popliteal injury with angiography. Splint and elevation (D) may be appropriate once a vascular injury is ruled out. The patient should not be discharged home (A) with an abnormal ABI. Observation and repeat ABI (B) is indicated if the initial ABI is normal.

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