Questions, Board Review

Board Review Questions: April 2021

PEER (Physician's Evaluation and Educational Review in Emergency Medicine) is ACEP’s gold standard in self-assessment and educational review. These questions are from PEER, updated continually on its digital platform. Order PEER to prepare!

A 78-year-old man presents with a newly elevated BUN of 56 and a creatinine level of 4.1. His medical history is significant for prostate cancer, and a physical examination reveals a tender suprapubic mass. Digital rectal examination is limited by the presence of a large nodular mass. What is the best next step?
A. Discontinue nephrotoxic medications and remeasure the creatinine level
B. Order abdominal and pelvic CT with contrast to evaluate the extent of the tumor
C. Order urine electrolytes to calculate the fractional excretion of sodium
D. Place a Foley catheter into the bladder to relieve the obstruction

The correct answer is D, Place a Foley catheter into the bladder to relieve the obstruction.

Why is this the correct answer?
This patient has an acute kidney injury (AKI) from postrenal obstruction of the bladder outflow due to a large prostate mass. The next step should be to relieve the obstruction with a urinary catheter, which may be sufficient to reverse the AKI. Bladder, cervical, and prostate cancers are well-recognized causes of bilateral postrenal obstruction. A quick bedside ultrasound examination can easily identify urinary obstruction; examiners may see hydronephrosis of one or both kidneys or enlargement of the bladder. Any urinary obstruction identified should be promptly relieved by placing a urinary catheter or arranging for urgent nephrostomy stenting.

One of the first steps in evaluating AKI is to determine if the problem is prerenal, renal, or postrenal. Prerenal AKI is the appropriate compensatory renal response to low circulating plasma volume. If a patient is severely dehydrated or has relative hypovolemia from sepsis, the kidneys respond by restricting urinary output, leading to rising BUN and creatinine levels (azotemia). Intrinsic kidney insults (eg, exogenous toxins, nephrotoxic medications leading to acute tubular necrosis, or glomerulonephritis) result in decreased renal function. Prerenal AKI should be treated primarily by adequate intravenous volume replacement. Postrenal obstruction restricting the output of urine flow also leads to decreased renal function and azotemia. Theoretically, this should happen only when there is bilateral obstruction: One normally functioning kidney should be able to compensate for the decreased function of the other obstructed kidney. In practice, however, patients with chronic conditions such as diabetes and hypertension may have a baseline subclinical renal dysfunction and demonstrate significant azotemia and renal failure from a single obstructed kidney. Large kidney stones and surgical misadventures severing a ureter are two examples of unilateral postrenal obstruction.

Why are the other choices wrong?

  • The patient's medication list should be thoroughly examined for any nephrotoxic medications or drugs that require adjustment for renal dysfunction. However, it takes time to reverse acute tubular necrosis, so other more expedient solutions should be examined first (such as relieving bladder obstruction).
  • Radiographic exploration for the extent of the tumor may be indicated after the initial obstruction is relieved. Although recent studies are changing practice, the use of contrast is not recommended in the setting of AKI if the contrast image is not emergent.
  • The use of urinary electrolytes to calculate the fractional excretion of sodium — or FENa — is very helpful in separating prerenal from renal causes of AKI. The formula for calculating FENa is ([plasma Cr ⨉ urinary Na] / [plasma Na ⨉ urinary Cr]) ⨉ However, the process of obtaining the urine sample in this patient would treat the underlying obstruction.

REFERENCES


2. What is the most likely cause of a single second heart sound with a harsh systolic ejection murmur in an infant?
A. Coarctation of the aorta
B. Tetralogy of Fallot
C. Tricuspid atresia
D. Truncus arteriosus

The correct answer is B, Tetralogy of Fallot.

Why is this the correct answer?
Tetralogy of Fallot (TOF) is one of the cyanotic congenital heart diseases that can present during the neonatal period or during infancy and childhood. TOF is the most common structural congenital heart disease occurring outside the neonatal period. Common physical examination findings in TOF include a right ventricular heave and a harsh systolic ejection murmur with a single second heart sound (without pulmonic valve component). The four features of the TOF defect are: 

  • A large ventricular septal defect (VSD)
  • Right ventricular outflow tract obstruction
  • An overriding aorta
  • Right ventricular hypertrophy

The murmur of TOF softens as the severity of obstruction worsens because more blood is being shunted across the VSD. In patients with TOF, the severity of the outflow obstruction determines the time of symptom onset and appearance of the disease. Severe obstruction causes cyanosis in the newborn (blue tet), and less severe obstruction (pink tet) can delay diagnosis.

Why are the other choices wrong?

  • Coarctation of the aorta is a congenital narrowing of the aorta, occurring most commonly at the level of the ductus arteriosus. Infants with coarctation are often asymptomatic and have normal SpO2 levels as blood bypasses the obstruction when the ductus arteriosus is patent. As the ductus closes, the systemic circulation can be compromised, causing shock. If the narrowing is less severe, the coarctation might not be diagnosed until later in life. Significant physical examination findings are blood pressure or perfusion deficits in the upper compared to the lower extremities. A harsh systolic ejection murmur may also be heard radiating from the left axilla to the back.
  • Tricuspid atresia is characterized by complete absence of the tricuspid valve, a hypoplastic right ventricle, and the presence of a VSD. The size of the VSD determines the amount of pulmonary blood flow. A large VSD can allow for relatively normal pulmonary blood flow and delay detection. Because the left ventricle is the only functional chamber, fluid overload easily occurs, causing heart failure and hepatomegaly in the young. Infants with small VSDs are dependent on the ductus arteriosus for pulmonary blood flow, and tricuspid atresia is often diagnosed during the neonatal period as the ductus arteriosus closes and cyanosis develops. On physical examination, a harsh systolic ejection murmur with a single or split second sound is heard; however, tricuspid atresia is less common in infants and less likely to be the cause of these sounds.
  • Truncus arteriosus is the presence of a single trunk arising from the heart that functions as both the aorta and the pulmonary artery. A single semilunar valve and VSD are present, allowing the complete mixing of systemic and pulmonary blood. As the pulmonary resistance falls after birth and blood travels preferentially through the pulmonary circuit, heart failure ensues. The common physical examination findings include a wide pulse pressure with a systolic ejection murmur and a single second heart sound.

REFERENCES

  • Mick NW. Pediatric cardiac disorders. In: Adams JG, Barton ED, Collings JC, DeBlieux PMC, Gisondi MA, Nadel ES, eds. Emergency Medicine Clinical Essentials. 2nd ed. Elsevier Saunders; 2013:159-166.
  • Horeczko T, Inaba AS. Cardiac disorders. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 2. 9th ed. Elsevier; 2018:2099-2125.

3. Which characteristic of a breast mass is most likely to represent fibrocystic changes?
A. Fluctuance
B. Nipple retraction
C. Nodularity
D. Skin thickening

The correct answer is C, Nodularity.

Why is this the correct answer?
Fibrocystic changes are the most common cause of breast lesions in women. These noncancerous lesions are described as nodular, mobile, and smooth. As the name describes, the breast tissue develops numerous cystic structures from dilatation of the ducts that are mixed with excessive fibrous tissue. A breast that has undergone these changes can become tender with menstrual cycle changes. Several radiologic imaging techniques have been used to make sure that changes noted on physical examination are not indicative of cancer, including ultrasonography, mammography, and MRI. These changes occur in at least one third of women of child-bearing age. In contrast, cancerous lesions are generally firmer and more irregular in shape. Enlarged lymph nodes associated with breast cancer initially are described as rubbery; they become matted and fixed when found in association with breast cancer.

Why are the other choices wrong?

  • A fluctuant breast mass likely represents an abscess; it can be identified using ultrasonography or mammography. Although the label fibrocystic might imply fluctuance of a mass due to its cystic nature, the small size of the cysts and more prominent dense stromal tissue create the classic bumpy, nonfluctuant feel on palpation of the characteristic fibrocystic changes.
  • Nipple retraction is a sign found in cancer and not found in fibrocystic changes. The retraction is a result of fibrosis that can pull the nipple toward the breast and chest wall. Bloody, unilateral nipple discharge is another concerning sign that can indicate the presence of a breast carcinoma.
  • Breast cancer also can cause skin changes, including discoloration, thickening, and dimpling. Classic characteristics of the skin changes in inflammatory breast cancer are skin thickening and an erythema called peau d'orange (orange peel). Some abscesses can cause erythema, but fibrocystic disease does not cause this particular change in the appearance of the skin.

REFERENCES

  • Hang BS. Breast disorders. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill; 2020:658-663.
  • Amin M. Breast masses and infections. In: Wolfson AB, Cloutier RL, Hendey GW, Ling LJ, Rosen CL, Schaider JJ, eds. Harwood-Nuss’ Clinical Practice of Emergency Medicine. 7th ed. Wolters Kluwer; 2021:694-697.
  • Healthline information on breast cancer
  • https://www.healthline.com/health/breast-cancer/pictures

4. A 2-year-old boy presents via ambulance in shock after his mother found him unconscious and pale. He arouses only to painful stimuli; icteric sclera is noted, and there is oozing from the intravenous line. The mother says he had vomiting and diarrhea 2 days ago that resolved overnight. He has no significant medical history, no allergies to medications, and no history of liver disease. The pH on a venous blood gas is 7.26. What is the best initial treatment?
A. Activated charcoal
B. Deferoxamine
C. Ipecac
D. Vitamin B6

The correct answer is B, Deferoxamine.

Why is this the correct answer?
This patient is in the third of four phases of iron toxicity, and he requires treatment for both the shock state and the hepatic injury. Decontamination should be performed with chelation using deferoxamine. Phase 1 of iron toxicity is characterized by vomiting and diarrhea as the iron has a direct effect on the gastric mucosa. If the toxicity is severe enough, the patient can present with signs of shock and bloody vomiting or diarrhea associated with metabolic acidosis. In phase 2, there is resolution of the GI symptoms. This phase can last for 6 to 24 hours, and patients treated during this phase often have a complete recovery. It is during this phase that the iron begins to injure the liver itself, which can lead to the signs and symptoms of phase 3. In phase 3, there is more acidosis associated with seizures or shock status, and there are signs of hepatic failure with alteration in gluconeogenesis. Jaundice and elevated transaminases develop during this phase. Phase 4 occurs in those who survive the iron ingestion and are at risk of developing pyloric stenosis. Most toxic iron incidents are the result of prenatal vitamin ingestion because these tablets have a high concentration of elemental iron. Toxicity can occur with doses as low as 20 mg/kg, and ingestion of 50 mg/kg or more is likely to lead to symptoms of toxicity.

Why are the other choices wrong?

  • Activated charcoal is not effective in GI decontamination of iron toxicity. Iron is a substance to which charcoal does not bind.
  • Ipecac is no longer recommended for the management of ingested poisonings. Instead, decontamination should be performed with chelation using deferoxamine.
  • Vitamin B6 (pyridoxine) should be used as an antidote for isoniazid toxicity, not iron toxicity. This patient should receive deferoxamine for decontamination.

REFERENCES

  • Renny MH, O’Donnell KA, Calello DP. Toxicologic emergencies. In: Shaw KN, Bachur EG, Chamberlain J, Lavelle J, Nagler J, Shook JE, eds. Fleisher & Ludwig's Textbook of Pediatric Emergency Medicine. 8th ed. Wolters Kluwer; 2021:1029-1083.
  • Christian MR, Algren DA. Iron. In: Wolfson AB, Cloutier RL, Hendey GW, Ling LJ, Rosen CL, Schaider JJ, eds. Harwood-Nuss’ Clinical Practice of Emergency Medicine. 7th ed. Wolters Kluwer; 2021:1469-1472.

5. What is a critical initial intervention in the emergency department for a patient with a high-pressure paint injection injury to the tip of the index finger?
A. Administration of tetanus prophylaxis 
B. Early and aggressive cleansing of the wound 
C. Early consultation with a hand specialist 
D. Performance of a digital nerve block to relieve pain

The correct answer is C, Early consultation with a hand specialist.

Why is this the correct answer?
Patients who present with seemingly innocuous findings after high-pressure injection injury can see their conditions rapidly deteriorate. Early consultation is critical to allow for timely surgical decompression and debridement. Less viscous substances can penetrate deeper with less pressure, leading to worsened outcomes. Paint and paint thinners produce a large and early inflammatory response, and the rate of associated amputation is high. Even when patients present soon after injury and with little pain and minimal other findings, prompt consultation with a hand specialist is recommended. Symptoms can develop and progress rapidly to inflammation and swelling and to ischemia and tissue death. Getting the consultation with a hand specialist right away helps prevent delayed surgical management when it is necessary.

Why are the other choices wrong?

  • Initial emergency department management of an injection injury generally consists of pain control, x-rays, splinting, intravenous administration of antibiotics, and tetanus prophylaxis. However, these are not high-risk injuries for tetanus, and prophylaxis, even if indicated, does not need to be performed immediately. In fact, none of the emergency department interventions, outside of pain control, are likely as important as recognition of the potential severity of the injury and early consultation with a hand specialist.
  • The proper way to clean puncture wounds remains debatable, but in this case, no amount of cleansing in the emergency department is likely to make a difference in outcome. The concern with injection wounds is not the superficial puncture but the deep penetration of substances that can lead to increased compartment pressures as well as a robust inflammatory response.
  • Digital blocks are excellent tools to relieve pain and provide anesthesia without distorting the field during wound repair. However, in this case, increased compartment pressures in the finger might lead to tissue ischemia. Injecting an anesthetic agent into the tissue planes and finger compartments can increase the pressure and worsen the injury. There might also be theoretical concerns related to difficulty following the physical examination. In patients with injuries such as the one in this question, systemic pain control using intravenous administration is a better choice.

REFERENCES

  • Quinn J. Puncture wounds and bites. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill; 2020:317-324.
  • Simon BC, Hern HG. Wound management principles. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 1. 9th ed. Elsevier; 2018:659-673.
  • A briefing on hydraulic injection injuries, from the Health and Safety Laboratory for the Health and Safety Executive (United Kingdom)
  • https://www.hse.gov.uk/research/rrpdf/rr976.pdf

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