Episode 23 – SBO and Mesenteric Ischemia

(ITUNES OR LISTEN HERE)

The Free Open Access Medical Education (FOAM)

This week we’re covering Dr. Jacob Avila’s post on ultrasound for small bowel obstruction (SBO)  located at Ultrasound of the week.  He has an accompanying video on 5minSono.

Point of care ultrasound has good operating characteristics for diagnosis of SBO with a LR+ 9.5, LR- 0.04, far better than abdominal x-ray [1].

Screen Shot 2015-01-25 at 10.20.44 AM

What to look for:

  • Dilated loops of bowel > 2.5 cm in diameter
  • Additional clues:  “To and fro” peristalsis
  • The piano key sign, Tanga sign
Piano Key Sign
Piano Key Sign

Problems with abdominal x-ray:

  • Rosen’s: Abdominal x-rays are “diagnostic in approximately 50 to 60% of cases of SBO, equivocal in 20 to 30%, and normal, nonspecific, or misleading in 10 to 20%” [2].
  • American College of Radiology: they can “prolong the evaluation period … while often not obviating the need for additional examinations, particularly CT” [3].

Limitations:

  • While ultrasound can diagnose SBO, there is little evidence to suggest that we can identify transition points or strangulation/necrosis.  As such, there can still be a role for CT scan, particularly in first time SBO to identify a transition point.
  • The EAST guidelines acknowledge the utility of ultrasound yet this practice is far from accepted in the surgical community.  Surgical colleagues will likely still want concrete imaging such as an x-ray or CT; however, ultrasound performed concurrent with the history and physical may speed up patient’s disposition to definitive care/imaging.
Possible algorithm for use of US in SBO
Possible algorithm for use of US in SBO

More FOAM on the topic:

The Bread and Butter

We cover key points on SBO and Acute Mesenteric Ischemia from Rosenalli, that’s Tintinalli (7e) Chapter 86; Rosen’s (8e) Chapter 92.  But, don’t just take our word for it.  Go enrich your fundamental understanding yourself.

Small Bowel Obstruction

Etiology of intestinal obstruction: “HANG IV.” Hernia, Adhesions (most common cause), Neoplasm, Gallstone ileus, Intussusception, Volvulus

Treatment

  • Intravenous fluids – resuscitate the patient!
  • Antiemetics.  If a patient is compromising their airway, an aspiration risk, or vomiting despite antiemetics, consider the use of a nasogastric tube.  Shockingly, “use of nasogastric decompression is considered dogma by many emergency physicians and surgeons, its effect in decreasing the duration of SBO has scant support in the medical literature” [2, 5].  This point demonstrates that SBO is not a monolithic disease entity but a spectrum of pathology with variable treatments depending on patient’s sickness.
  • Antibiotics that cover gram-negative and anaerobic organisms
  • Admit. Most of these patients will likely go to the surgical service; however,

Acute Mesenteric Ischemia

Screen Shot 2015-01-24 at 7.18.02 PM

 Generously Donated Rosh Review Questions (scroll for answers)

Question 1. A 73-year-old man presents with vomiting and abdominal pain for 2 days. The patient has a remote history of cholecystectomy and appendectomy. Examination reveals a markedly distended abdomen and absent bowel sounds. Lab studies show an elevated WBC count and a lactate of 4.3 mmol/L. An abdominal radiograph is obtained that is shown below. [polldaddy poll=8607202]

Screen Shot 2015-01-26 at 8.40.19 AM

Question 2. An 87-year-old woman presents with worsening abdominal pain over the last 24 hours. She has minimal tenderness on examination but an elevated lactic acid. An abdominal CT Scan demonstrates mesenteric ischemia. [polldaddy poll=8607198]

References:

1. Taylor MR, Lalani N. Adult small bowel obstruction. Acad Emerg Med. 2013;20(6):528–44.

2. Roline CE, Reardon RF.  “Disorders of the Small Intestine.  Rosen’s Emergency Medicine.  8th ed. pp 1216-1224.e2.

3. Ros PR, Huprich JE. ACR Appropriateness Criteria on suspected small-bowel obstruction. J Am Coll Radiol. 2006;3:(11)838-41.

4. Vicario SJ, Price TG.  “Bowel Obstruction and Volvulus.” Tintinalli’s Emergency Medicine: A Comprehensive Study Guide.  7th ed. pp 581-583.

5.  Fonseca AL, Schuster KM, Maung AA, Kaplan LJ, Davis KA. Routine nasogastric decompression in small bowel obstruction: is it really necessary? Am Surg. 2013;79:(4)422-8.

Answers.

1. D. This patient presents with a high-grade small bowel obstruction (SBO) with evidence of bowel ischemia (elevated lactate). Mortality has fallen in the last century with aggressive surgical treatment (from 60% to 5%). The abdominal radiograph above shows multiple air-fluid levels consistent with an SBO. Radiographs are abnormal in 50-60% of cases and are more likely to demonstrate abnormality when the obstruction is high-grade versus partial. Two views (upright and supine or supine and decubitus) should be obtained. Mechanical obstruction refers to the presence of a physical barrier to the flow of intestinal contents. In a simple obstruction, the intestinal lumen is partially or completely obstructed causing intestinal distension proximally but does not cause compromise of the vascular supply. In a closed-loop obstruction, a segment of bowel is obstructed at two sequential sites usually by twisting on a hernia opening or adhesive band leading to compromise of blood flow eventually resulting in bowel ischemia. Ischemia may only be seen on CT scan or occasionally, on laparoscopy or laparotomy. However, an elevated lactate in the setting of an SBO is highly suggestive of intestinal ischemia. The presence of blood in stool (either gross blood or guaiac positive stools) also suggests the presence of ischemia or infarction. When compromise of the vascular supply is suspected, the patient should have an emergent surgical consultation for operative management. Immediate management should also include placement of a nasogastric tube for decompression of the proximal parts of the intestines, intravascular volume resuscitation and intravenous antibiotics when vascular compromise is suspected or confirmed. CT scan of the abdomen and pelvis (A) is considered complimentary to plain films and is more sensitive and specific. Additionally, CT scan can reveal the site and cause of obstruction. However, surgical evaluation of a high-grade SBO should not be delayed for advanced imaging. Colonoscopy (B) is not indicated in small bowel obstruction. There is an increased risk of perforation. An enema and polyethylene glycol (C) is the treatment for constipation, and may worsen the outcome in patients with high-grade bowel obstruction.

2. Arterial emboli account for more than 50% of cases of mesenteric ischemia. The classic presentation of mesenteric ischemia is abdominal pain out of proportion to examination. Most commonly, thrombi develop in the left ventricle or atrium and embolize into the aorta. From the aorta, the emboli pass into one of the branches supplying the circulation to the gut. Thesuperior mesenteric artery is the most common site of embolization because of its large diameter and narrow angle of takeoff from the aorta. Mesenteric ischemia usually involves the small intestine and sometimes the right colon. The large intestine has significantly more collateral flow and is not as susceptible to ischemia. Aortic dissection (A) may lead to mesenteric ischemia depending on the location of the dissection. It is also possible to have a primary dissection of the mesenteric blood supply (e.g. SMA).Primary arterial thrombosis (C) of the mesentery is much less common and arises from progression of underlying atherosclerotic disease. Patients will often have a history of intestinal “angina” or chronic mesenteric ischemia during which symptoms occur after eating when the gut requires additional blood supply which is limited by the atherosclerotic changes. Venous thrombosis (D) is the least common etiology of mesenteric ischemia and most commonly affects the superior mesenteric vein.

FOAMcastini – Reflections on ACEP tPA Clinical Policy Update Draft

(iTunes or Listen Here)

As detailed in this FOAMcastini, ACEP just released a draft of an updated clinical policy on tPA for acute ischemic stroke.  This came in the wake of years of controversy over the aggressive position taken in the 2012 clinical policy.

While FOAMcast is not an interview style podcast, we felt compelled to get some perspective on Emergency Physicians a little more experienced than ourselves.  Here we interview:

Dr. Ryan Radecki (@emlitofnote), Assistant Professor, University of Texas – Houston

  • We don’t know who best benefits from tPA so elucidating which patients are “carefully selected” may get hard.
  • See his response to the policy on his blog here

Dr. David Newman (#draftnewman), Associate Professor of Emergency Medicine, Mount Sinai Hospital

  • The process for ACEP clinical policy creation seems to work.  The constituency expressed concern and the college listened and went back and re-created the policy from the bottom up.
  • This policy reflects a move from content expert to methodologists which better reflects the evidence compared with opinions (and is the standard per USPSTF).

Dr. Anand Swaminathan (@EMSwami), Assistant Professor of Emergency Medicine, NYU

  • Inclusion of more rigorous methodology and review of evidence.
  • May be perceived as too “soft” by tPA supporters.  This policy may not overtly change practice but may open up avenue of conversations.

Dr. Ken Milne (@thesgem), Chief of Staff at South Huron Hospital

  • When looking at “carefully selected” patients, as noted in the policy, remember to use the Evidence Based Medicine trifecta of evidence, patient values, and clinical expertise.  In isolation, one component is not sufficient.
  • Previous discussions of NINDS, and the Cochrane tPA article

FOAMcastini – ACEP tPA Clinical Policy Update

(ITUNES OR LISTEN HERE)

The Free Open Access Medical Education (FOAM)

Comment on the 2015 ACEP tPA Clinical Policy Draft here

ACEP tPA Clinical Policy 2012 – This policy has been entrenched in controversy since it was published.  Why?  Well, largely because the evidence was given a stronger level recommendation than the data supported, conflicts of interest abounded, and the data (mostly from NINDS (The SGEM review), ECASS, and IST-3) were problematic.  This has been well covered by these reviews of the clinical policy:

What changed in the 2015 draft?

Screen Shot 2015-01-13 at 10.22.04 AM

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.

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 http://www.mindanews.com/buy-imitrex/ 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.