Episode 54 – The Pericardium

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We cover ultrasound guided pericardiocentesis using the posts from EMin5, CoreEM, and the Ultrasound Podcast.

Historically, pericardiocentesis is taught using a landmark based method; however, use of ultrasound guidance may increase success.  Experts recommend an approach wherever the largest pocket of fluid exists and each location has particular downsides to be aware of.

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Core Content

We delve into core content on the pericardium using Rosen’s (8th ed) Chapter 82 and Tintinalli (8th ed) Chapter 55.

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Generously Donated Rosh Review Questions

1.A 25-year-old man presents to the ED with chest pain, shortness of breath, and fever. Vital signs include BP 98/50 mm Hg, HR 136 beats/minute, RR 26 breaths/minute, and T 102.4°F. On auscultation, you hear rales to the mid-thorax bilaterally. Bedside cardiac ultrasound shows global hypokinesis and a small pericardial effusion. Which of the following organisms is the most common cause of this condition worldwide?

A. Coxsackievirus B

B. Mycobacterium tuberculosis

C. Plasmodium falciparum

D. Trypanosoma cruzi

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    [toggle title=”Answers” state=”closed”]D. Trypanosoma cruz.  This patient presents with signs and symptoms of myocarditis accompanied by pericarditis. Myocardial injury results from inflammation of the myocardium. The most common etiology worldwide is Chagas disease, caused by the protozoan Trypanosoma cruzi. The protozoan is spread by the reduviid bug, also known as the kissing bug as it feeds on the faces of those affected. Unfortunately, in many patients, the cause of myocarditis is idiopathic. Other noninfectious causes include connective tissue disorders such as scleroderma, toxins such as chemotherapy, cocaine, and heavy metals, and peripartum myocarditis. Symptoms often include a viral prodrome with fever, myalgias, and generalized weakness. Patients may present with chest pain, symptoms of acute heart failure, tachycardia, dysrhythmias, syncope, cardiogenic shock, or even sudden cardiac death. Diagnosis can be very difficult and patients often present to the ED multiple times prior to being diagnosed. An ECG may show global or segmental ST elevation, nonspecific ST segment and T wave changes, dysrhythmias, or conduction delays. Troponin and creatinine phosphokinase are often elevated. Echocardiography classically shows global hypokinesis. Management is primarily supportive; however, patients with new left bundle branch block or low ejection fraction may require a left ventricular assist device as a bridge to cardiac transplantation in some cases as these are poor prognostic indicators. The most common long-term sequelae of myocarditis is dilated cardiomyopathy.[/toggle]
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2.A 56-year-old woman with a history of lymphoma presents to the Emergency Department at the recommendation of her primary care physician. During a routine visit, she had a chest X-ray that showed a “big heart.” She denies chest pain, shortness of breath, leg swelling, cough, orthopnea, or lightheadedness. Her vital signs include temperature 98.6 ºF, HR 88 beats/minute and regular, RR 14 breaths/minute, BP 121/89 mm Hg, and oxygen saturation 98% on room air. Her cardiac and neck exams are within normal limits. A bedside ultrasound reveals a small pericardial effusion. Which of the following is the next best step in management?

A.Lower extremity ultrasound

B. Pericardiocentesis

C. Reassurance and close follow up

D. Thoracic Surgery consultation

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[toggle title=”Answers” state=”closed”] C.  Reassurance and close follow up. The patient likely has a malignant pericardial effusion secondary to her known malignancy. Pericardial effusions are accumulations of fluid in the pericardial space that occur rapidly or gradually. Rapid accumulation of pericardial effusion can produce tamponade physiology and hypotension. This requires pericardiocentesis for emergent decompression of the effusion. Pericardial effusions that develop gradually often occur secondary to cancer (e.g. lymphoma, lung cancer, breast cancer, melanoma) or as the result of cancer treatment (e.g. radiation). Clinical signs or symptoms are determined by the rate of fluid accumulation. Asymptomatic pericardial effusions require no immediate treatment. Echocardiography is the diagnostic tool of choice. Chest X-ray may show a large cardiac silhouette indicating gradual fluid accumulation within a stretched pericardium. Malignant pericardial effusions can be managed in a variety of ways, including systemic or intrapericardial chemotherapy, or a pericardial window with pericardial resection. Lower extremity venous ultrasound (A) is an imaging modality to evaluating and diagnosing a deep venous thrombosis (DVT). This patient has no clinical features suggesting a DVT. Pericardiocentesis (B) is indicated in patients with symptomatic pericardial effusions or those who are experiencing tamponade physiology with hypotension. Thoracic surgery consultation (D) is not indicated since the patient is asymptomatic and hemodynamically stable.

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3. A 4-year-old girl is brought to the ER by her parents due to lethargy. A week prior the girl had a cough and colds. Later symptoms progressed to include fever and malaise. She has been less active with decreased appetite. A few hours prior to arrival in the ER, she has been having difficulty of breathing. On exam, temperature is 38.3°C, respiratory rate of 35, heart rate of 126, blood pressure of 90/60, clear breath sounds, hepatomegaly, and poor pulses. Which of the following is the most likely diagnosis?

A. Bronchiolitis

B. Dysrhythmia

C. Myocarditis

D.  Pneumonia

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    [toggle title=”Answers” state=”closed”]The girl demonstrates signs and symptoms that are suspicious for myocarditis which is a condition that results from inflammation of the heart muscle. Majority of children present with acute or fulminant disease. Myocarditis can be caused by infectious, toxic, or autoimmune conditions. Common causes of viral myocarditis include enterovirus (coxsackie group B), adenovirus, parvovirus B19, Epstein-Barr virus, cytomegalovirus, and human herpes 6 (HHV-6). The presentation of the disease is variable and patients can present with broad symptoms that range from subclinical disease to cardiogenic shock, arrhythmias, and sudden death. There is usually a history of a recent respiratory or gastrointestinal illness within the previous weeks. There is a prodrome of fever, myalgia, and malaise several days prior to the onset of symptoms of heart dysfunction. Then patients present with heart failure symptoms that include dyspnea at rest, exercise intolerance, syncope, tachypnea, tachycardia, and hepatomegaly. Testing is focused on determining the severity of cardiac dysfunction and these include electrocardiography (ECG), cardiac biomarkers, chest radiography, and echocardiography. Confirmation of myocarditis is generally made by cardiac magnetic resonance imaging or endomyocardial biopsy.

Dysrhythmia (B) usually presents with palpitations, syncope, chest pain. In the vignette, the girl’s symptoms are more consistent with a myocarditis. A primary dysrhythmia resulting in myocardial injury is differentiated from myocarditis by an endomyocardial biopsy. Bronchiolitis (A) is typically a disease in children younger than two years of age. It is diagnosed clinically with the characteristic findings of a viral upper respiratory prodrome followed by increased respiratory effort. Pneumonia (D) usually presents with respiratory complaints, particularly cough, tachypnea, retractions, and abnormal lung examination which were not present in the vignette.

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Episode 23 – SBO and Mesenteric Ischemia

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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].

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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

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 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]

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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.