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A 52-year-old man with a history of exploratory laparotomy 5 years ago presents with severe abdominal pain, nausea, and vomiting. His last bowel movement was 3 days ago. Placement of a nasogastric tube yields copious bilious material. Given the presumed diagnosis, which abdominal x-ray finding is most likely?
- Bowel wall thickening
- Dilated bowel with prominent haustra
- Dilated bowel with prominent plicae circulares
- Distended U-shaped loop of bowel
The correct answer is C, Dilated bowel with prominent plicae circulares.
Why is this the correct answer?
Knowing that this patient's medical history includes an exploratory laparotomy, the entire clinical picture is suggestive of small bowel obstruction (SBO) due to adhesions. SBO is approximately four times more common than large bowel obstruction (LBO), accounting for approximately 15% of all emergency admissions for abdominal pain. Classic x-ray findings for SBO include distended loops of bowel (>3 cm in diameter) and prominent plicae circulares (valvulae conniventes) that go across the entire bowel (the coiled spring sign). These findings are in contrast to haustra of the large intestine, which do not cross the full diameter of the bowel. Generally, the greater the number of distended loops, the more distal the obstruction. CT has higher sensitivity and specificity for detecting SBO and also provides more information regarding the potential cause of the obstruction.
Why are the other choices wrong?
Bowel wall thickening is generally seen with colonic inflammation in conditions such as diverticulitis. It is generally not seen in SBO.
Haustra are present on the large bowel and do not cross the entire bowel. SBO is much more common than LBO.
A distended U-shaped loop of bowel, often called the coffee bean sign or the bent inner tube sign, is seen in sigmoid volvulus. When the volvulus occurs, the bowel folds back on itself, with the two medial walls touching. Sigmoid volvulus is a cause of LBO and occurs when the sigmoid colon twists on the sigmoid mesocolon.
REFERENCES
Roline CE, Reardon RF. Small intestine. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 1. 10th ed. Elsevier; 2023:1093-1104.
Price TG. Bowel obstruction. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill Education; 2020:530-532.
Hucl T. Acute GI obstruction. Best Pract Res Clin Gastroenterol. 2013 Oct;27(5):691-707.
Foster NM, McGory ML, Zingmond DS, Ko CY. Small bowel obstruction: a population-based appraisal. J Am Coll Surg. 2006 Aug;203:170-176.
UpToDate article on SBO in adults, available in full with a subscription
Which statement describes the clinical manifestations of hypoglycemia?
- Bradycardia occurs frequently
- Dry skin is present
- Focal neurologic deficits can occur
- Pulse pressure is decreased
The correct answer is C, Focal neurologic deficits can occur.
Why is this the correct answer?
The neurologic deficits associated with most toxic and metabolic causes of significant altered levels of consciousness (including hypoglycemia) are typically symmetrical (nonfocal). However, a small, but not insignificant, number of patients with hypoglycemia present with focal neurologic deficits, including hemiplegia. The rapid identification and correction of hypoglycemia in all patients, including those with focal neurologic deficits, is critical to avoid severe complications, unnecessary imaging (brain imaging), and potential interventions (thrombolytic therapy).
Why are the other choices wrong?
Although adrenergic symptoms, such as diaphoresis and tachycardia, are common manifestations of hypoglycemia, bradycardia is less common. None of these symptoms should be relied on to determine if a patient is hypoglycemic.
Because of the release of epinephrine during a hypoglycemic episode, adrenergic symptoms such as diaphoresis, not dry skin, are seen. Other symptoms include palpitations, tachycardia, nervousness, and tremors.
Release of the counterregulatory hormone epinephrine in the setting of hypoglycemia can result in a variety of adrenergic symptoms (eg, anxiety, diaphoresis, palpitations, tachycardia, or tremors). There is typically a small increase in the systolic blood pressure but a drop in the diastolic pressure, causing an increase, not a decrease, in the pulse pressure.
REFERENCES
Graffeo CS. Hyperosmolar hyperglycemic state. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill Education; 2020:1443-1447.
Votey SR, Peters AL. Hypoglycemia. 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; 2021:1051-1057.
UpToDate article on hypoglycemia in adults without diabetes mellitus, available in full with a subscription
An intoxicated 52-year-old man presents with altered mental status after using phencyclidine. His laboratory evaluation is significant for a CK level of 5,100 U/L and tea-colored urine. What is the most appropriate treatment?
- Alkalinization of urine
- Diuresis with mannitol
- Intravenous antibiotics
- Intravenous hydration
The correct answer is D, Intravenous hydration.
Why is this the correct answer?
Rhabdomyolysis is diagnosed by laboratory analysis that reveals a CK level of at least five times the level of normal (ABEM's normal range is 30-170 U/L) in addition to the presence of myoglobin in the urine. Aggressive intravenous hydration is the mainstay of treatment for rhabdomyolysis. Urine output should be targeted to 3 to 4 mL/kg/hr. No specific type of crystalloid has been shown to be of particular benefit. If rhabdomyolysis is left undiagnosed or progresses to advanced stages, disseminated intravascular coagulation (DIC) and myoglobin-induced kidney injury can ensue.
Early in the course of rhabdomyolysis, complications such as compartment syndrome, hypovolemia, and hepatic dysfunction are known to occur. Electrolyte disturbances and acidosis are the greatest threats; hyperkalemia and hypocalcemia are the most common electrolyte abnormalities and pose the greatest risk for arrhythmias. Kidney failure begins later in the course as the result of myoglobin being deposited in renal tubules and obstructing them in the presence of aciduria. This, combined with hypovolemia, further reduces the glomerular filtration rate and worsens renal failure. The worse the renal failure, the worse the hyperkalemia can be. In severe forms of this condition, prothrombotic substances are released and cause DIC and hemorrhagic complications.
Why are the other choices wrong?
There is no evidence to suggest that urine alkalinization is a necessary goal in the treatment of rhabdomyolysis. However, aggressive intravenous hydration is necessary, and urine output should be targeted to 3 to 4 mL/kg/hr. Avoiding acidosis is important, so some physicians continue to use sodium bicarbonate in conjunction with intravenous fluids to avoid this complication. Bicarbonate should be reserved for those patients with severe rhabdomyolysis.
Mannitol and other diuretics have not been shown to provide any benefit in the treatment of rhabdomyolysis. Mannitol may actually cause an osmotic diuresis that can worsen a patient's hypovolemic state. Mannitol should be reserved for patients with volume overload, if used at all.
There is no indication that this patient has a UTI, so antibiotics are unlikely to be of benefit. Some antibiotics, particularly macrolides, may actually precipitate rhabdomyolysis either alone or in combination with other medications and risk factors.
REFERENCES
Long B, Koyfman A. Rhabdomyolysis. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 2. 10th ed. Elsevier; 2023:1559-1565.
Counselman, FL. Rhabdomyolysis. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill Education; 2020:570-572.
UpToDate article on preventing and treating heme pigment-induced acute kidney injury, available in full with a subscription
Which drug is used as a first-line agent for smoking cessation?
- Clonidine
- Nortriptyline
- Sertraline
- Varenicline
The correct answer is D, Varenicline.
Why is this the correct answer?
Varenicline is a nicotinic acetylcholine receptor partial agonist, specifically at the alpha-4 beta-2 and alpha-6 beta-2 receptors, which are the receptors most strongly associated with nicotine dependence. Previously, varenicline was associated with neurobehavioral abnormalities, most prominently suicidal ideation, and it carried an associated black box warning. However, later studies showed no conclusive evidence of these effects, and the black box warning was removed. Varenicline commonly causes side effects such as headache, GI upset, and insomnia.
The therapeutic mechanism of action for smoking cessation is to both block nicotine from fully stimulating the receptor and to provide partial agonism; this partial agonism reduces cravings and withdrawal symptoms. This mechanism is in contrast to nicotine replacement therapy, which is also first line for smoking cessation. Nicotine can be provided in various forms, such as a patch or chewable gum. Unlike varenicline, which is a partial agonist, nicotine is a full agonist; nicotine replacement therapy provides the same receptor-level effects as the nicotine inhaled from tobacco smoking. Bupropion is another first-line agent for smoking cessation.
Why are the other choices wrong?
Clonidine is an alpha-2 receptor agonist that has ultimately been found to have limited efficacy with an undesirable side effect profile. Undesirable side effects of clonidine include sedation, fatigue, and rebound hypertension if abruptly discontinued.
Nortriptyline is a tricyclic antidepressant with broad monoamine reuptake inhibition. It can be used for smoking cessation, but it is generally considered a second-line agent behind varenicline, nicotine replacement therapy, and bupropion. Nortriptyline causes undesirable side effects typical of tricyclic antidepressants, such as drowsiness and dry mouth.
Sertraline is a selective serotonin reuptake inhibitor (SSRI) that is primarily used for managing depression and anxiety. In contrast to bupropion and nortriptyline, there is no current evidence to suggest SSRIs are effective for smoking cessation directly. However, their use may still be indicated for treating comorbid depression and anxiety.
REFERENCES
Burns DM. Nicotine addiction. Loscalzo J, Fauci A, Kasper D, Hauser S, Longo D, Jameson J, eds. Harrison's Principles of Internal Medicine. 21st ed. McGraw-Hill Education; 2022:3563-3567.
Tonstad S, Arons C, Rollema H, et al. Varenicline: mode of action, efficacy, safety and accumulated experience salient for clinical populations. Curr Med Res Opin. 2020;36(5):713-730.
UpToDate article on pharmacotherapy for smoking cessation, available in full with a subscription
What is a contraindication to ultrasound-guided thoracentesis?
- Creatinine level 5.2 mg/dL
- Loculated effusions
- Mechanical ventilation
- Skin infection overlying the site
The correct answer is D, Skin infection overlying the site.
Why is this the correct answer?
Contraindications to thoracentesis are infection of the skin overlying the site of thoracentesis, insufficient pleural fluid, and severe bleeding diathesis. In most cases of skin infection overlying the thoracentesis site, an alternative site can be found with ultrasound. The indications for emergent thoracentesis include possible pleural space infection, to relieve dyspnea, and for diagnostic purposes in the evaluation of a new effusion of unclear etiology.
The procedure is performed similarly to a paracentesis or central venous access using the Seldinger technique. Lidocaine should be injected to anesthetize the skin and rib space. The finder needle is then walked up and over the rib to minimize the risk of injury to the neurovascular bundle. Air bubbles in the syringe can indicate that the needle has entered the lung parenchyma, so the placement of the needle should be adjusted. A catheter is threaded over the needle, and a stopcock is placed to drain the fluid. The lowest space recommended to minimize complications is between the eighth and ninth intercostal spaces; performing a thoracentesis more inferiorly increases the risk of diaphragmatic, splenic, or hepatic injury. The complications associated with thoracentesis include pneumothorax, infection, hemothorax, reexpansion pulmonary edema, air embolism, and intra-abdominal hemorrhage.
Why are the other choices wrong?
Although patients with end-stage renal disease may have bleeding diatheses, a creatinine level of 5.2 mg/dL is not considered a contraindication to thoracentesis. A creatinine level greater than 6 mg/dL is a relative contraindication to thoracentesis.
In patients with loculated effusions, ultrasound should be used to determine the best site for thoracentesis. The use of ultrasound minimizes the risk of complications such as pneumothorax.
Mechanical ventilation is not a contraindication to thoracentesis. Although patients on mechanical ventilation are more likely to experience complications such as pneumothorax, the risk remains low.
REFERENCES
Blok BK. Thoracentesis. In: Roberts JR, Custalow CB, Thomsen TW, et al, eds. Roberts and Hedges’ Clinical Procedures in Emergency Medicine and Acute Care. 7th ed. Elsevier; 2019:181-195.
UpToDate article on ultrasound-guided thoracentesis, available in full with a subscription
McVay PA, Toy PT. Lack of increased bleeding after paracentesis and thoracentesis in patients with mild coagulation abnormalities. Transfusion. 1991;31(2):164-171.