All practice questions

8270 questions

All types8,270 Multiple choice4,249 Multiple select325 Numeric160 Matching1,849 Ordering1,687

Following 4 days of profuse, watery diarrhea, a 70-year-old man with a long-standing history of severe chronic obstructive pulmonary disease presents to the emergency department for evaluation of extreme weakness. He reports having 8 to 10 bowel movements daily since attending a family picnic. His home medications include a long-acting muscarinic antagonist and an inhaled corticosteroid.

Vital signs show a temperature of $37.4^\circ\text{C}$ ( $99.3^\circ\text{F}$ ), blood pressure of 102/64 mm Hg, pulse of 115/min, and respiratory rate of 14/min. Physical examination reveals dry mucous membranes, decreased skin turgor, and diffuse expiratory wheezes bilaterally.

Laboratory studies are obtained:

Parameter	Value
Sodium	$140 \text{ mEq/L}$
Potassium	$2.9 \text{ mEq/L}$
Chloride	$114 \text{ mEq/L}$
Bicarbonate	$16 \text{ mEq/L}$
Blood urea nitrogen	$35 \text{ mg/dL}$
Creatinine	$1.4 \text{ mg/dL}$

Arterial blood gas on room air:

Parameter	Value
pH	$7.15$
$PaCO_2$	$48 \text{ mm Hg}$
$PaO_2$	$62 \text{ mm Hg}$

Which of the following best describes this patient's primary acid-base disturbance?

Normal anion gap metabolic acidosis and respiratory acidosis

Normal anion gap metabolic acidosis with adequate respiratory compensation

High anion gap metabolic acidosis and respiratory acidosis

Normal anion gap metabolic acidosis and respiratory alkalosis

Chronic respiratory acidosis with fully compensated metabolic alkalosis

Show answer & explanation

Answer: Normal anion gap metabolic acidosis and respiratory acidosis

Answer

Normal anion gap metabolic acidosis and respiratory acidosis

The patient's severe diarrhea leads to direct gastrointestinal loss of bicarbonate, causing a primary normal anion gap metabolic acidosis (NAGMA). In a healthy individual, the expected physiologic response is hyperventilation to blow off

CO_2

. Using Winter's formula (

PaCO_2 = 1.5 \times [\text{HCO}_3^-] + 8 \pm 2

), the expected

PaCO_2

for this patient should be between

30

and

34 \text{ mm Hg}

. However, his actual

PaCO_2

48 \text{ mm Hg}

. Because his actual

PaCO_2

is much higher than the expected compensatory range, he has a superimposed respiratory acidosis. This occurs because his severe underlying COPD prevents him from adequately increasing his minute ventilation to compensate for the metabolic acidemia.

Step-by-Step Solution

Determine the primary disturbance by looking at pH and bicarbonate.

The pH is

7.15

(acidemia) and bicarbonate is

16 \text{ mEq/L}

(low). This establishes a primary metabolic acidosis.

Acidemia with a corresponding decrease in serum bicarbonate indicates that a metabolic acidosis is the primary driving process.

Calculate the anion gap (AG) to classify the metabolic acidosis.

\text{AG} = \text{Na}^+ - (\text{Cl}^- + \text{HCO}_3^-) = 140 - (114 + 16) = 10 \text{ mEq/L}

An AG of

10 \text{ mEq/L}

falls within the normal range (

8-12 \text{ mEq/L}

), identifying a normal anion gap metabolic acidosis (NAGMA).

Calculate the expected respiratory compensation using Winter's formula.

Expected

PaCO_2 = (1.5 \times 16) + 8 \pm 2 = 32 \pm 2 \text{ mm Hg}

(Range:

30-34 \text{ mm Hg}

Winter's formula determines if the lungs are appropriately blowing off

CO_2

to compensate for the primary metabolic acidosis.

Compare the actual

PaCO_2

to the expected

PaCO_2

range.

The actual

PaCO_2

48 \text{ mm Hg}

, which is significantly higher than the expected

30-34 \text{ mm Hg}

Because the actual

PaCO_2

is higher than expected, there is a concomitant, uncompensated primary respiratory acidosis.

Key Concept

Patients with underlying chronic lung disease (like COPD) may fail to mount an appropriate respiratory compensation (hyperventilation) to a primary metabolic acidosis, resulting in a mixed metabolic and respiratory acidosis.

Question 7802Question →

An independent $72$ -year-old male presents to the acute care clinic with a $6$ -hour history of severe, crampy left-sided abdominal pain and two episodes of bright red blood per rectum. Over the preceding three days, he experienced a viral gastroenteritis characterized by frequent watery stools and poor oral intake, which caused him to feel lightheaded upon standing. His past medical history includes heart failure with preserved ejection fraction, hypertension, and hyperlipidemia. His current medications are lisinopril, metoprolol, and atorvastatin.

Vital signs are heart rate $112\text{/min}$ , blood pressure $105/65\text{ mm Hg}$ , respiratory rate $18\text{/min}$ , and oxygen saturation $96\%$ on room air. Physical examination shows dry mucous membranes and decreased skin turgor. The abdomen is soft but moderately tender to palpation in the left lower quadrant. There is no rebound tenderness, rigidity, or guarding. Bowel sounds are diminished.

Laboratory studies show:
Leukocyte count: $10,500\text{/mm}^3$
Hemoglobin: $14.2\text{ g/dL}$
Creatinine: $1.4\text{ mg/dL}$ (baseline $0.9\text{ mg/dL}$ )
Lactic acid: $1.6\text{ mmol/L}$ (normal: $0.5-2.2\text{ mmol/L}$ )

A CT scan of the abdomen with intravenous contrast reveals edema and thickening of the colonic wall isolated to the splenic flexure and descending colon. There is no evidence of pneumatosis intestinalis or free intraperitoneal air.

Which of the following is the most appropriate next step in management?

Intravenous fluid resuscitation and bowel rest

Immediate exploratory laparotomy

Administration of intravenous meropenem

Administration of intravenous furosemide

Administration of intravenous sodium bicarbonate

Show answer & explanation

Answer: Intravenous fluid resuscitation and bowel rest

Answer

The correct approach is supportive management with intravenous fluid resuscitation and bowel rest.

The correct response provides the mainstay of treatment for nonocclusive ischemic colitis: supportive care. Ischemic colitis most commonly affects older adults following episodes of systemic hypotension or hypovolemia (e.g., severe diarrhea). The splenic flexure (Griffith point) and rectosigmoid junction (Sudeck point) are watershed areas highly vulnerable to decreased arterial flow. Because this patient lacks "red flag" surgical signs—such as peritonitis, hemodynamic collapse, lactic acidosis, or pneumatosis intestinalis on CT—the immediate goal is to restore colonic perfusion through intravenous fluid resuscitation and bowel rest.

Step-by-Step Solution

Analyze the clinical presentation and history.

The patient has acute left-sided abdominal pain and hematochezia following a dehydrating illness, leading to hypovolemia (elevated creatinine, dry mucous membranes, tachycardia).

Identifying the low-flow state is critical to determining the etiology of the intestinal ischemia.

Interpret the diagnostic imaging.

CT shows wall thickening at the splenic flexure without pneumatosis or free air.

This confirms nonocclusive ischemic colitis at a watershed area and rules out perforation or transmural gangrene.

Determine the appropriate intervention.

Select supportive medical management to restore perfusion.

Because the ischemia is nonocclusive and there are no signs of peritonitis, surgical and aggressive antibiotic therapies are deferred in favor of restoring circulating volume.

Key Concept

Management of nonocclusive ischemic colitis focuses on supportive care, including intravenous fluid resuscitation, to restore colonic perfusion in patients without signs of peritonitis or bowel necrosis.

Estimated Time:1m 15s

Question 7803Question →

A 24-year-old male is brought to the emergency department by helicopter after colliding with a tree while skiing at high speed. On arrival, his blood pressure is $76/40$ mmHg, heart rate is $138$ /min, and respiratory rate is $26$ /min. The patient is confused, pale, and diaphoretic. The trachea is midline, and breath sounds are equal bilaterally without chest wall crepitus. The abdomen is distended with diffuse tenderness and involuntary guarding. The pelvis is mechanically stable to gentle anteroposterior and lateral compression. Bilateral large-bore peripheral intravenous lines are placed, and resuscitation with type O negative packed red blood cells is initiated. A bedside Focused Assessment with Sonography for Trauma (FAST) reveals a large anechoic collection in the splenorenal recess and the rectovesical pouch. Which of the following is the most appropriate next step in management?

Exploratory laparotomy

Computed tomography of the abdomen and pelvis with intravenous contrast

Diagnostic peritoneal lavage to confirm the predictive value of the ultrasound findings

Admission to the surgical intensive care unit for serial abdominal examinations

Defer intervention until a surrogate decision-maker can provide informed consent

Show answer & explanation

Answer: Exploratory laparotomy

Answer

Exploratory laparotomy

The correct answer is exploratory laparotomy. This patient presents with hemorrhagic shock secondary to blunt trauma. The primary survey localizes the pathology to the abdomen, which is subsequently confirmed by a positive FAST exam showing intraperitoneal fluid. According to Advanced Trauma Life Support (ATLS) principles, the combination of hemodynamic instability and a positive FAST dictates immediate transport to the operating room for an exploratory laparotomy to identify and stop the bleeding.

Step-by-Step Solution

Evaluate the patient's hemodynamic status.

The patient is in class III/IV hypovolemic shock (blood pressure

76/40

mmHg, heart rate

138

/min, confusion).

Hemodynamic instability dictates the treatment algorithm in trauma, shifting focus from comprehensive diagnostics to immediate life-saving intervention.

Analyze primary survey findings to isolate the source of hemorrhage.

Chest exam is normal (rules out massive hemothorax or tension pneumothorax) and pelvis is stable. The abdomen is distended with guarding.

Identifying the anatomic compartment of bleeding determines the specific surgical or procedural intervention required.

Interpret the adjunct imaging (FAST exam).

The FAST exam is positive, demonstrating anechoic free fluid (blood) in dependent intraperitoneal spaces.

A positive FAST in the setting of blunt trauma confirms the abdomen as the source of major hemorrhage.

Determine the next best step based on ATLS protocols.

The patient requires an immediate exploratory laparotomy.

An unstable patient with a confirmed intra-abdominal source of bleeding requires emergent surgical exploration for hemostasis.

Key Concept

Hemodynamically unstable patients with blunt abdominal trauma and a positive FAST exam require emergent exploratory laparotomy.

Question 7804Question →

Match each clinical presentation of suspected adrenal or pituitary pathology with the most appropriate initial diagnostic or screening test.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The presentations match their respective screening tests based on the suspected underlying hormonal excess or deficiency: primary hyperaldosteronism matches the aldosterone to renin ratio, pheochromocytoma matches plasma free metanephrines, Cushing syndrome matches 24-hour urine free cortisol, and primary adrenal insufficiency matches the morning cortisol with cosyntropin stimulation test.

Each clinical vignette presents classic hallmark signs of a specific adrenal disorder. Primary hyperaldosteronism presents with hypertension and hypokalemia and is screened with an aldosterone-to-renin ratio. Pheochromocytoma presents with episodic headaches, diaphoresis, and palpitations, and is screened with plasma free metanephrines. Cushing syndrome presents with hypercortisolism signs (striae, proximal weakness) and is screened with a 24-hour urine free cortisol or dexamethasone suppression test. Primary adrenal insufficiency presents with hypotension, fatigue, and hyperpigmentation, and is diagnosed using a cosyntropin stimulation test.

Step-by-Step Solution

Analyze the first clinical presentation (hypertension, hypokalemia) to identify the suspected diagnosis.

The suspected diagnosis is primary hyperaldosteronism (Conn syndrome).

Excess aldosterone causes sodium retention (hypertension) and renal potassium wasting (hypokalemia).

Select the appropriate screening test for primary hyperaldosteronism.

Plasma aldosterone concentration to plasma renin activity ratio.

Autonomous aldosterone production suppresses renin, resulting in an elevated aldosterone-to-renin ratio.

Analyze the second presentation (paroxysmal palpitations, severe headaches, diaphoresis, hypertension).

The suspected diagnosis is pheochromocytoma.

These are the classic symptoms of catecholamine excess.

Select the appropriate screening test for pheochromocytoma.

Measurement of plasma free metanephrines.

Metanephrines are the continuously released metabolic byproducts of catecholamines from the tumor.

Analyze the third presentation (central obesity, proximal muscle weakness, wide striae).

The suspected diagnosis is Cushing syndrome (hypercortisolism).

These physical findings are specific for excessive tissue exposure to glucocorticoids.

Select the appropriate screening test for Cushing syndrome.

Measurement of 24-hour urine free cortisol or overnight 1-mg dexamethasone suppression test.

These tests assess for an inappropriate elevation in cortisol production or a lack of expected suppression.

Analyze the fourth presentation (fatigue, hypotension, mucosal hyperpigmentation).

The suspected diagnosis is primary adrenal insufficiency (Addison disease).

Loss of cortisol and aldosterone causes fatigue and hypotension; loss of cortisol removes negative feedback on ACTH, leading to high ACTH and MSH (causing hyperpigmentation).

Select the appropriate screening test for primary adrenal insufficiency.

Measurement of early morning serum cortisol and cosyntropin stimulation test.

Cosyntropin (synthetic ACTH) should normally stimulate cortisol production; failure to do so confirms adrenal insufficiency.

Key Concept

Recognition of classic adrenal pathology syndromes and selection of their respective initial screening laboratory tests.

Estimated Time:1m 30s

Question 7805Question →

Match each clinical presentation and urinalysis finding with the most likely underlying renal pathology.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Contrast-induced injury with muddy brown casts matches Acute tubular necrosis. Nafcillin-induced injury with WBC casts matches Acute interstitial nephritis. Post-impetigo injury with RBC casts matches Glomerulonephritis. Diabetic nephropathy with fatty casts matches Nephrotic syndrome.

The correct pairings rely on identifying the hallmark urinalysis findings and clinical risk factors for each renal pathology. Acute tubular necrosis is characterized by muddy brown casts following an ischemic or nephrotoxic insult. Acute interstitial nephritis is indicated by white blood cell casts and eosinophils following exposure to an offending drug. Glomerulonephritis is diagnosed by red blood cell casts in the setting of nephritic syndrome symptoms. Nephrotic syndrome presents with heavy proteinuria, hypoalbuminemia, and fatty casts.

Step-by-Step Solution

Analyze the first patient's history of recent radiocontrast administration and the presence of muddy brown granular casts.

Identify this pattern as characteristic of acute tubular necrosis (ATN).

Contrast is a known nephrotoxin that damages tubular cells, which slough off and form muddy brown casts.

Evaluate the second patient's presentation of fever, rash, and new medication exposure (nafcillin) alongside white blood cell casts.

Identify this pattern as acute interstitial nephritis (AIN).

AIN is an allergic inflammatory reaction in the kidney interstitium, often drug-induced, characterized by WBCs and eosinophils.

Assess the third patient's post-infectious presentation (impetigo) featuring hypertension, edema, and red blood cell casts.

Identify this pattern as glomerulonephritis.

RBC casts form when red blood cells leak through a damaged glomerular basement membrane, a hallmark of acute nephritic syndrome.

Review the fourth patient's long-standing diabetes, profound hypoalbuminemia, and fatty casts in the urine.

Identify this pattern as nephrotic syndrome.

Severe proteinuria leads to hypoalbuminemia and a compensatory increase in hepatic lipid synthesis, resulting in lipiduria (fatty casts).

Key Concept

Urinalysis sediment interpretation in the differential diagnosis of acute kidney injury and proteinuric states.

Question 7806Question →

A $34$ -year-old man comes to the clinic due to a $2$ -week history of right upper quadrant abdominal pain, fever, and significant fatigue. He returned from a $6$ -month backpacking trip across Southeast Asia and India approximately $1$ month ago. During his trip, he experienced an episode of severe, bloody diarrhea that resolved after $5$ days with over-the-counter oral rehydration. His temperature is $38.7^\circ\text{C}$ ( $101.7^\circ\text{F}$ ), pulse is $102/\text{min}$ , and blood pressure is $118/76\text{ mm Hg}$ . Physical examination reveals a moderately enlarged liver with marked point tenderness to palpation in the right subcostal region. There is no scleral icterus.

Laboratory studies show:

Test	Result
Leukocyte count	$14,500/\text{mm}^3$
Neutrophils	$82\%$
Eosinophils	$2\%$
Aspartate aminotransferase (AST)	$68\text{ U/L}$
Alanine aminotransferase (ALT)	$75\text{ U/L}$
Alkaline phosphatase	$310\text{ U/L}$
Total bilirubin	$1.1\text{ mg/dL}$

An abdominal ultrasound reveals a solitary, $7\text{-cm}$ , round, hypoechoic cystic lesion in the right hepatic lobe with no internal septations.

Which of the following is the most appropriate next step in management?

Initiation of oral metronidazole therapy

CT-guided percutaneous aspiration and drainage

Intravenous piperacillin-tazobactam administration

Initiation of oral albendazole therapy

Endoscopic retrograde cholangiopancreatography

Show answer & explanation

Answer: Initiation of oral metronidazole therapy

Answer

The most appropriate next step is the initiation of oral metronidazole therapy.

The clinical presentation of a young man with recent travel to an endemic area, a preceding episode of bloody dysentery, fever, right upper quadrant pain, and a solitary hypoechoic mass in the right hepatic lobe on ultrasound is classic for an amebic liver abscess caused by Entamoeba histolytica. The diagnosis is definitively confirmed with serologic testing (e.g., E. histolytica IgG antibodies), but empiric medical therapy with oral metronidazole should be initiated immediately when clinical suspicion is high. Following the tissue amebicide (metronidazole), a luminal agent (such as paromomycin or intraluminal iodoquinol) must be given to eradicate intestinal colonization and prevent relapse. Unlike pyogenic liver abscesses, percutaneous drainage is not routinely required and is reserved for large abscesses at high risk of rupture (e.g., left lobe abscesses near the pericardium) or when there is no clinical improvement after 3 to 5 days of medical therapy.

Step-by-Step Solution

Analyze the patient's epidemiologic risk factors and symptom timeline.

The patient is a young male with recent travel to endemic regions (India, Southeast Asia) and a recent history of bloody dysentery, now presenting with fever and right upper quadrant pain.

Identifying travel history and preceding infections helps narrow the differential diagnosis for hepatic lesions, pointing strongly toward a protozoal etiology.

Evaluate the laboratory and imaging findings.

Labs show leukocytosis and an isolated elevated alkaline phosphatase without jaundice. Ultrasound reveals a solitary, hypoechoic cystic mass in the right hepatic lobe.

This classic triad (epidemiology, clinical presentation, solitary right-lobe hypoechoic mass) is highly characteristic of an amebic liver abscess caused by Entamoeba histolytica.

Determine the standard of care for the suspected diagnosis.

Uncomplicated amebic liver abscesses are treated medically with a tissue amebicide (metronidazole) followed by a luminal agent (paromomycin) to eradicate intestinal colonization.

Unlike pyogenic abscesses, percutaneous drainage is not routinely indicated for amebic abscesses unless rupture is imminent or medical therapy fails.

Key Concept

Diagnosis and management of amebic liver abscesses versus other hepatic cystic lesions.

Estimated Time:1m 30s

Question 7807Question →

An orthopedic surgery team is consulted regarding a post-operative complication in an 82-year-old male patient. The patient underwent an uncomplicated left hemiarthroplasty three days ago following a femoral neck fracture. His past medical history is significant for Parkinson disease, essential hypertension, and chronic kidney disease. Over the last 24 hours, the nursing staff reports that he has developed progressive, marked abdominal swelling and has not passed any flatus or stool. He complains of mild, generalized abdominal discomfort and nausea but has not vomited. His current pain management regimen includes scheduled acetaminophen and as-needed intravenous hydromorphone.

His temperature is 37.1°C (98.8°F), pulse is 92/min, blood pressure is 135/85 mm Hg, and respiratory rate is 16/min. Physical examination reveals a profoundly distended and tympanitic abdomen. Bowel sounds are diminished. There is mild, diffuse palpation tenderness, but no guarding, rigidity, or rebound tenderness is elicited. An upright plain radiograph of the abdomen demonstrates marked gaseous distension of the ascending colon and cecum, with the cecal diameter measuring 10.5 cm. The distal colon contains scattered air, and there is no evidence of pneumoperitoneum.

Which of the following represents the most appropriate initial intervention for this patient's current gastrointestinal presentation?

Cessation of the current intravenous opioid and institution of supportive care

Intravenous administration of neostigmine

Endoscopic decompression of the large intestine

Urgent exploratory laparotomy

Initiation of broad-spectrum intravenous antimicrobial therapy

Show answer & explanation

Answer: Cessation of the current intravenous opioid and institution of supportive care

Answer

Cessation of the current intravenous opioid and institution of supportive care

The correct intervention involves stopping the offending medication and providing supportive care. This patient's clinical presentation and radiographic findings (massive right colonic dilation without anatomical obstruction or pneumoperitoneum) are highly characteristic of acute colonic pseudo-obstruction, also known as Ogilvie syndrome. It most commonly occurs in elderly, hospitalized patients following surgery (such as orthopedic procedures) or severe illness. The pathogenesis involves autonomic dysfunction leading to parasympathetic suppression and sympathetic overactivity, which is frequently exacerbated by medications such as opioids and anticholinergics. Because the patient is hemodynamically stable, lacks signs of peritonitis, and the cecal diameter is less than 12 cm (indicating a lower immediate risk of perforation), the most appropriate initial management is strictly conservative. This includes making the patient nil per os (NPO), providing intravenous fluid resuscitation, placing a nasogastric and/or rectal tube for decompression, and immediately discontinuing offending pharmacological agents like intravenous hydromorphone.

Step-by-Step Solution

Analyze the patient's presentation and radiographic findings.

The patient is an elderly postoperative male with massive right-sided colonic dilation (cecum measuring 10.5 cm) but no mechanical obstruction or peritonitis.

To establish the diagnosis of acute colonic pseudo-obstruction (Ogilvie syndrome).

Assess the risk of impending cecal perforation.

The cecal diameter is 10.5 cm, which is below the high-risk threshold of 12 cm. There are no peritoneal signs.

To determine whether conservative or aggressive (pharmacological or invasive) management is indicated.

Identify contributing factors and determine the initial intervention.

The patient is receiving intravenous hydromorphone, an opioid that decreases bowel motility. The initial step is to stop this medication and begin conservative supportive care.

Conservative management is the standard first-line treatment for Ogilvie syndrome without high-risk features.

Key Concept

The initial management of acute colonic pseudo-obstruction (Ogilvie syndrome) in stable patients with a cecal diameter < 12 cm consists of strictly conservative measures: bowel rest, fluid resuscitation, and discontinuation of offending medications (e.g., opioids, anticholinergics).

Estimated Time:1m 15s

Question 7808Question →

A $29$ -year-old man comes to the outpatient clinic due to a painful swelling on his right thigh. He first noticed a "pimple" in the area $4$ days ago, which has progressively enlarged and become increasingly tender. He has no significant past medical history and takes no medications. Vital signs show a temperature of $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure of $122/78$ mm Hg, and heart rate of $76$ /min. Physical examination of the anterior right thigh reveals a $4$ -cm, erythematous, exquisitely tender, and fluctuant mass. There is a $0.5$ -cm rim of surrounding erythema. No induration extending beyond the erythema is noted, and there is no inguinal lymphadenopathy. Which of the following is the most appropriate next step in management?

Incision and drainage alone

Incision and drainage followed by oral trimethoprim-sulfamethoxazole

Incision and drainage followed by oral cephalexin

Oral trimethoprim-sulfamethoxazole alone

Warm compresses and observation

Show answer & explanation

Answer: Incision and drainage alone

Answer

Incision and drainage alone

The correct answer is incision and drainage alone. The patient presents with a classic cutaneous abscess (a purulent skin and soft tissue infection), characterized by a localized, fluctuant, and erythematous mass. According to standard infectious disease guidelines, a purulent infection is classified as 'mild' if there are no systemic signs of infection (e.g., fever, tachycardia, tachypnea, leukocytosis) and the patient is immunocompetent. For mild purulent infections, mechanical source control via incision and drainage is the definitive and only required treatment. Systemic antimicrobial therapy is not recommended in this scenario, as it does not significantly improve cure rates but does contribute to antimicrobial resistance and potential adverse drug effects.

Step-by-Step Solution

Identify the primary clinical finding.

The patient has a 4-cm fluctuant, tender, erythematous mass, which is diagnostic of a cutaneous abscess (purulent skin and soft tissue infection).

Establishing the correct diagnosis determines the treatment algorithm (purulent vs. non-purulent infection).

Assess the severity of the infection.

The patient has normal vital signs (temperature 37.0°C, heart rate 76/min), a small rim of erythema, and no comorbidities.

Severity classification (mild, moderate, or severe) dictates whether systemic antibiotics are required in addition to source control.

Determine the appropriate intervention based on severity.

Because this is a mild, uncomplicated abscess, source control via incision and drainage is the only required intervention.

According to infectious disease guidelines, adding systemic antibiotics to incision and drainage for mild purulent infections does not significantly improve clinical cure rates but does increase adverse events and antibiotic resistance.

Key Concept

Management of uncomplicated cutaneous abscesses requires incision and drainage alone without systemic antimicrobial therapy.

Question 7809Question →

Match each clinical presentation of a hypotensive patient with their most likely corresponding hemodynamic profile obtained via pulmonary artery catheterization. The parameters include central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI), and systemic vascular resistance (SVR).

Click a left item, then click its matching right item

Show answer & explanation

Answer

Cardiogenic shock (myocardial infarction) pairs with increased CVP and PCWP, decreased CI, and increased SVR. Hypovolemic shock (hemorrhage) pairs with decreased CVP, PCWP, and CI, and increased SVR. Septic shock (infection) pairs with decreased CVP, PCWP, and SVR, and increased CI. Obstructive shock (pulmonary embolism) pairs with increased CVP, decreased PCWP and CI, and increased SVR.

Each shock state has a distinct hemodynamic signature. Distributive shock is the only type with decreased SVR and increased CI. Cardiogenic shock is the only type with both increased CVP and increased PCWP. Obstructive shock is uniquely characterized by increased CVP but decreased PCWP due to the blockage occurring between the right and left heart. Hypovolemic shock is characterized by globally decreased pressures (CVP, PCWP) with decreased CI and high SVR.

Step-by-Step Solution

Identify the underlying type of shock based on the clinical scenario.

The scenarios describe cardiogenic shock (myocardial infarction), hypovolemic shock (hemorrhage), distributive/septic shock (infection), and obstructive shock (massive pulmonary embolism).

Accurate diagnosis of the shock etiology is required before applying physiological principles to deduce the expected hemodynamic parameters.

Determine the right-sided and left-sided filling pressures (CVP and PCWP).

Cardiogenic shock elevates both pressures due to left ventricular failure backing up into the lungs and right heart. Obstructive shock (PE) elevates right-sided pressures (CVP) but prevents blood from reaching the left heart (decreasing PCWP). Hypovolemic and septic shock both feature low filling pressures due to absolute or relative volume depletion.

Filling pressures distinguish cardiogenic and obstructive causes from hypovolemic and distributive causes.

Analyze the systemic vascular resistance (SVR) and cardiac index (CI).

Septic shock is unique for its primary severe vasodilation (low SVR) and compensatory high CI. The other three types (cardiogenic, hypovolemic, obstructive) all present with a primary low CI and a compensatory high SVR.

SVR and CI help isolate distributive shock from the other shock etiologies.

Key Concept

Hemodynamic profiles of the major types of shock (Cardiogenic, Hypovolemic, Distributive, and Obstructive) as measured by pulmonary artery catheterization.

Question 7810Question →

A 32-year-old male is brought to the emergency department after being rescued from a structure fire. He sustained deep partial-thickness and full-thickness thermal burns involving his entire anterior chest and abdomen, his entire right lower extremity, and his entire right upper extremity. The patient currently weighs $80\text{ kg}$ . The injury occurred exactly $2\text{ hours}$ prior to his arrival at the emergency department. Two large-bore peripheral intravenous lines are placed. Following current Advanced Trauma Life Support (ATLS) guidelines for adult thermal burns (which recommend $2\text{ mL/kg/\%TBSA}$ ), what should be the initial continuous intravenous infusion rate of lactated Ringer solution in $\text{mL/hr}$ ?

Show answer & explanation

Answer: 600

Answer

600

The patient requires an initial fluid infusion rate of

600\text{ mL/hr}

. According to the Rule of Nines, the TBSA burned is

45\%

(anterior trunk

18\%

+ right leg

18\%

+ right arm

9\%

). Using the current ATLS recommendation for adult thermal burns (

2\text{ mL/kg/\%TBSA}

), the total 24-hour fluid requirement is

2 \times 80 \times 45 = 7200\text{ mL}

. Half of this volume (

3600\text{ mL}

) must be administered within the first 8 hours post-injury. Because 2 hours have already elapsed since the burn occurred, the

3600\text{ mL}

must be infused over the remaining 6 hours, yielding a rate of

600\text{ mL/hr}

Step-by-Step Solution

Calculate the Total Body Surface Area (TBSA) involved using the Rule of Nines.

Anterior chest and abdomen (18%) + right lower extremity (18%) + right upper extremity (9%) = 45% TBSA.

Accurate estimation of the burn area is required to calculate the fluid resuscitation volume.

Calculate the total 24-hour fluid requirement.

2 \text{ mL} \times 80 \text{ kg} \times 45\% = 7200 \text{ mL}

Current ATLS guidelines recommend 2 mL/kg/%TBSA for adult thermal burns to prevent over-resuscitation and subsequent compartment syndromes.

Determine the fluid volume targeted for the first 8 hours post-injury.

7200 \text{ mL} / 2 = 3600 \text{ mL}

Standard burn resuscitation protocols require half of the total calculated 24-hour volume to be administered in the first 8 hours.

Calculate the hourly infusion rate based on the time elapsed since the injury.

8 hours - 2 hours delay = 6 hours remaining.

3600 \text{ mL} / 6 \text{ hours} = 600 \text{ mL/hr}

The 8-hour window begins at the time of injury, not at the time of arrival. Fluid must be given over the remaining hours.

Key Concept

Burn resuscitation fluid calculation using the ATLS modified formula (2 mL/kg/%TBSA) and adjusting the hourly rate based on the time elapsed since the injury.

Question 7811Question →

A 55-year-old man is brought to the emergency department via ambulance after coughing up approximately 400 mL of bright red blood over the past hour. He has a history of treated pulmonary tuberculosis with residual cavitary disease in the right upper lobe. On arrival, he is in moderate respiratory distress and actively coughing up blood. Temperature is 37.1°C (98.8°F), blood pressure is 110/70 mm Hg, pulse is 118/min, and respirations are 28/min. Pulse oximetry shows an oxygen saturation of 86% on room air. Pulmonary auscultation reveals coarse rhonchi and gurgling over the right lung fields, with clear breath sounds over the left lung.

Arrange the following steps in the most appropriate sequential order for the acute management of this patient's massive hemoptysis.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence for managing massive hemoptysis is: 1) Secure the airway via endotracheal intubation, 2) Protect the non-bleeding lung by placing the patient in the right lateral decubitus position, 3) Localize the bleeding and attempt initial control using bronchoscopy, and 4) Provide definitive hemostasis via bronchial artery embolization.

In the management of massive hemoptysis (>600 mL/24 hours or >100 mL/hour), the greatest immediate threat to life is asphyxiation due to blood filling the airways, rather than hemorrhagic shock. Therefore, the absolute first step is to secure the airway with endotracheal intubation to ensure adequate ventilation and oxygenation. The next step is to protect the non-bleeding lung. Because this patient has a history of right-sided cavitary tuberculosis and isolated right-sided gurgling, the right lung is the source of bleeding. The patient should be placed in the right lateral decubitus position (bleeding lung down) so gravity prevents blood from spilling into the healthy left lung. Once the patient is stabilized, a bronchoscopy is indicated to visualize the exact bleeding site and attempt localized therapeutic interventions, such as balloon tamponade. Finally, because most massive hemoptysis originates from the systemic-pressure bronchial arteries, bronchial artery embolization is performed as the definitive procedure to permanently stop the bleeding.

Step-by-Step Solution

Prioritize airway management.

Perform endotracheal intubation.

The patient is expectorating massive amounts of blood and is hypoxic, putting him at imminent risk of asphyxiation.

Protect the unaffected lung.

Place the patient in the right lateral decubitus position.

Clinical signs (right-sided gurgling, right upper lobe cavitary disease history) point to the right lung as the bleeding source. Placing the right lung down prevents gravity-dependent blood flow into the healthy left lung.

Identify the exact bleeding source and attempt local control.

Perform bronchoscopy.

Direct visualization allows for interventions such as balloon tamponade, ice saline lavage, or topical vasoconstrictors to temporarily halt bleeding.

Perform definitive hemostasis.

Perform bronchial artery embolization.

The majority of massive hemoptysis originates from the high-pressure bronchial circulation; embolization definitively stops the bleeding in most cases.

Key Concept

Massive hemoptysis management prioritizes securing the airway to prevent asphyxiation, followed by positioning the patient with the bleeding lung in the dependent position to protect the non-bleeding lung. Bronchoscopy and bronchial artery embolization are subsequent steps for diagnosis and definitive hemostasis.

Question 7812Question →

A 58-year-old man presents to the clinic with progressive abdominal swelling, lower extremity edema, and exertional fatigue over the past 4 months. He has a history of Hodgkin lymphoma, for which he received mantle field radiation therapy 20 years ago. He has no history of tobacco or alcohol use. Vital signs are within normal limits. Physical examination shows marked jugular venous distension; the jugular venous pressure paradoxically increases during inspiration. Lung fields are clear to auscultation bilaterally. Cardiac auscultation reveals a regular rhythm and a high-pitched, early diastolic sound at the left sternal border. The abdomen is distended with a positive fluid wave, and the liver edge is palpable 4 cm below the right costal margin. Bilateral lower extremities demonstrate 2+ pitting edema up to the knees. An electrocardiogram reveals low-voltage QRS complexes in the limb leads. Which of the following is the most likely primary mechanism underlying this patient's presentation?

Decreased ventricular compliance due to a rigid pericardium

Chronic hypoxemia leading to pulmonary arterial hypertension

Ischemic injury causing left ventricular systolic dysfunction

Extracellular deposition of misfolded proteins in the myocardium

Rapid accumulation of fluid in the pericardial space

Show answer & explanation

Answer: Decreased ventricular compliance due to a rigid pericardium

Answer

Decreased ventricular compliance due to a rigid pericardium

The clinical presentation is classic for constrictive pericarditis. The patient exhibits signs of right-sided heart failure (ascites, hepatomegaly, lower extremity edema) without left-sided failure (clear lungs). Kussmaul sign (a paradoxical increase in jugular venous pressure during inspiration) and a pericardial knock (an early diastolic sound caused by the sudden cessation of ventricular filling) are pathognomonic. Mantle field radiation therapy for Hodgkin lymphoma is a well-known cause of radiation-induced fibrosis, which can lead to a rigid, noncompliant pericardium years or decades later. This rigid sac severely restricts diastolic filling, leading to decreased ventricular compliance.

Step-by-Step Solution

Analyze the patient's symptoms and physical exam findings.

The patient has signs of isolated right-sided heart failure (edema, ascites, hepatomegaly, jugular venous distension) with clear lungs.

Identifying the side of heart failure narrows the differential diagnosis to right heart pathologies, pulmonary vascular disease, or pericardial disease.

Identify specific pathognomonic physical exam and ECG findings.

The exam shows Kussmaul sign (paradoxical rise in JVP with inspiration) and a pericardial knock (high-pitched early diastolic sound). ECG shows low voltage.

These findings are highly specific for restricted diastolic filling caused by a pericardial abnormality.

Correlate the findings with the patient's past medical history.

The patient had mantle field radiation therapy for Hodgkin lymphoma 20 years ago, which strongly predisposes him to late-onset constrictive pericarditis.

Connecting the etiology (radiation) with the presentation (right heart failure + Kussmaul sign + knock) confirms the diagnosis.

Key Concept

Constrictive pericarditis is a potential late complication of mediastinal radiation therapy. It presents with signs of right-sided heart failure, Kussmaul sign, a pericardial knock, and low-voltage ECG due to a rigid, thickened pericardium restricting ventricular compliance.

Estimated Time:1m 30s

Question 7813Question →

A $68$ -year-old man is evaluated in the intensive care unit. He was admitted $2$ days ago for acute-on-chronic hypercapnic respiratory failure secondary to a severe chronic obstructive pulmonary disease (COPD) exacerbation. At the time of admission, he was lethargic. His pre-intubation arterial blood gas on room air showed:

* pH: $7.22$
* PaCO $_2$ : $86$ mm Hg
* PaO $_2$ : $52$ mm Hg
* HCO $_3^-$ : $34$ mEq/L

He was endotracheally intubated and initiated on mechanical ventilation. He is currently sedated with propofol and fentanyl and is making no spontaneous respiratory efforts. Current ventilator settings are as follows:

* Mode: Assist-control volume-cycled
* Tidal volume: $450$ mL ( $6$ mL/kg predicted body weight)
* Respiratory rate: $18$ /min
* FiO $_2$ : $0.40$
* PEEP: $5$ cm H $_2$ O

Current vital signs are temperature $37.0^\circ$ C ( $98.6^\circ$ F), blood pressure $125/80$ mm Hg, and heart rate $88$ /min. A repeat arterial blood gas today shows:

* pH: $7.55$
* PaCO $_2$ : $39$ mm Hg
* PaO $_2$ : $85$ mm Hg
* HCO $_3^-$ : $33$ mEq/L

Which of the following is the most appropriate next step in the management of this patient?

Decrease the set respiratory rate

Increase the set tidal volume

Administer intravenous furosemide

Administer intravenous acetazolamide

Increase the positive end-expiratory pressure

Show answer & explanation

Answer: Decrease the set respiratory rate

Answer

Decrease the set respiratory rate

The correct answer is to decrease the set respiratory rate. This patient has post-hypercapnic metabolic alkalosis. In severe COPD, chronic CO2 retention (hypercapnia) leads to compensatory renal retention of bicarbonate (HCO3-) to maintain the pH near normal. When this patient was placed on mechanical ventilation, his PaCO2 was rapidly lowered to a 'normal' level of 39 mm Hg. However, the kidneys require several days to excrete the excess bicarbonate. As a result, the chronically elevated bicarbonate is left unopposed, resulting in a severe alkalemia (pH 7.55). Severe alkalemia is dangerous and can cause arrhythmias, seizures, and decreased tissue oxygen delivery (due to a leftward shift of the oxyhemoglobin dissociation curve). The goal of mechanical ventilation in chronic CO2 retainers is to target their baseline PaCO2 (in this case, roughly 60-65 mm Hg), which will return their pH to a normal range. This is achieved by decreasing minute ventilation, most directly by decreasing the respiratory rate.

Step-by-Step Solution

Analyze the pre-intubation arterial blood gas (ABG) to determine the patient's baseline acid-base status.

The initial ABG shows a pH of 7.22, PaCO2 of 86 mm Hg, and HCO3- of 34 mEq/L.

This establishes that the patient has an acute-on-chronic respiratory acidosis. The elevated HCO3- (34 mEq/L) represents the long-standing renal metabolic compensation for his chronic hypercapnia.

Analyze the current ABG on mechanical ventilation.

The current ABG shows a pH of 7.55, PaCO2 of 39 mm Hg, and HCO3- of 33 mEq/L.

This identifies a severe alkalemia (pH > 7.45). The PaCO2 has been rapidly normalized to 39 mm Hg, but the HCO3- remains significantly elevated because renal excretion of excess bicarbonate takes several days.

Identify the primary pathophysiologic process causing the current alkalemia.

The patient has developed post-hypercapnic metabolic alkalosis.

The rapid correction of PaCO2 by mechanical ventilation in the setting of chronically elevated bicarbonate leaves the bicarbonate unopposed, driving the pH dangerously high.

Determine the optimal intervention to correct the acid-base derangement.

Minute ventilation must be decreased to allow PaCO2 to rise toward the patient's chronic baseline.

By reducing the respiratory rate, the ventilator will clear less CO2. A higher PaCO2 (e.g., 60-65 mm Hg) will balance the elevated HCO3-, returning the pH to a safe, physiological range.

Key Concept

Post-hypercapnic metabolic alkalosis occurs when mechanical ventilation rapidly normalizes PaCO2 in a patient with chronic hypercapnia and an elevated baseline bicarbonate. Management requires decreasing minute ventilation to allow PaCO2 to rise back toward the patient's baseline, thereby normalizing the pH.

Question 7814Question →

Match each patient's clinical exposure scenario with the most appropriate post-exposure prophylaxis or management strategy.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct matches require aligning the specific pathogen exposure with its guideline-directed prophylaxis: the sleeping bat exposure warrants rabies vaccine and immune globulin; the meningococcal roommate contact requires a single dose of ciprofloxacin; the non-immune pregnant woman exposed to varicella requires varicella-zoster immune globulin; and the pertussis household contact requires oral azithromycin.

Each exposure scenario necessitates a specific immunologic or antimicrobial prophylactic intervention. Unrecognized bat exposures while sleeping warrant full rabies PEP due to the high fatality of the disease. Meningococcal close contacts need ciprofloxacin, ceftriaxone, or rifampin to clear colonization. Non-immune pregnant women exposed to varicella require passive immunization (VZIG) because the live vaccine is contraindicated. Finally, pertussis household contacts need macrolide prophylaxis irrespective of past vaccination status.

Step-by-Step Solution

Analyze each clinical vignette to identify the suspected pathogen and the nature of the exposure.

Identified pathogens: Rabies virus, Neisseria meningitidis, Varicella-zoster virus, and Bordetella pertussis.

Post-exposure prophylaxis is highly pathogen-specific.

Assess host factors that influence prophylaxis selection, such as immunity status, age, and pregnancy.

Noted the pregnancy in the varicella exposure (contraindicating live vaccines) and the prior vaccination in the pertussis exposure (which does not preclude the need for antibiotics).

Host factors dictate whether active vaccination, passive immunity, or specific antimicrobial agents are safely indicated.

Match the exposure and host factors to the appropriate prophylactic intervention.

Bat exposure -> Rabies PEP; Meningococcal contact -> Ciprofloxacin; Pregnant varicella contact -> VZIG; Pertussis contact -> Azithromycin.

These pairings reflect the current standard of care for infectious disease post-exposure prophylaxis.

Key Concept

Post-exposure prophylaxis protocols for highly communicable or fatal infectious diseases

Question 7815Question →

Below are microscopic findings obtained from liver biopsies of various adult patients presenting with elevated liver enzymes or cholestatic markers. Match each histopathological description with the most appropriate disease process.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The accurate matches are: Hepatocyte ballooning/neutrophils with Alcoholic hepatitis; Florid duct lesions/granulomas with Primary biliary cholangitis; Concentric 'onion skin' fibrosis with Primary sclerosing cholangitis; and Lymphoplasmacytic infiltrate with Autoimmune hepatitis.

Each hepatobiliary disease possesses a signature histologic pattern on liver biopsy that reflects its distinct underlying pathophysiology. Recognizing these specific cellular infiltrates and architectural changes is critical for establishing a definitive diagnosis and guiding appropriate targeted therapy.

Step-by-Step Solution

Analyze the first histopathologic description focusing on Mallory-Denk bodies and a neutrophilic infiltrate.

Matched to alcoholic hepatitis.

Alcoholic liver disease uniquely features neutrophil-predominant inflammation and cytoskeletal damage (Mallory-Denk bodies) rather than a primarily lymphocytic response.

Evaluate the second description highlighting florid duct lesions and granulomas.

Matched to primary biliary cholangitis.

PBC is an autoimmune process causing granulomatous destruction of small, intrahepatic bile ducts.

Assess the third description noting concentric 'onion skin' periductal fibrosis.

Matched to primary sclerosing cholangitis.

PSC is characterized by fibro-obliterative inflammation of medium and large bile ducts, creating a classic 'onion skin' appearance.

Review the fourth description detailing a lymphoplasmacytic infiltrate with interface hepatitis.

Matched to autoimmune hepatitis.

Autoimmune hepatitis presents with plasma cell-rich inflammation attacking the hepatocyte junction (limiting plate).

Key Concept

Histopathologic differentiation of inflammatory and autoimmune hepatobiliary diseases

Question 7816Question →

A 64-year-old woman is evaluated on postoperative day 6 following an open partial gastrectomy for a refractory peptic ulcer. She complains of increasing pain at her surgical incision site and feeling feverish since yesterday. Her medical history includes type 2 diabetes mellitus and hypertension. Her temperature is 38.5°C (101.3°F), blood pressure is 135/85 mmHg, pulse is 98/min, and respiratory rate is 18/min. Oxygen saturation is 96% on room air. Lung auscultation reveals mild, scattered bibasilar crackles that clear with coughing. Cardiac examination is unremarkable. The abdomen is soft and non-distended, with normal active bowel sounds. Examination of the midline surgical incision reveals a 5-cm area at the inferior aspect that is exquisitely tender, erythematous, indurated, and fluctuant. There is no spontaneous drainage. Which of the following is the most appropriate next step in management?

Initiate broad-spectrum intravenous antibiotics and reassess in 24 hours

Obtain blood cultures, a urine culture, and a chest radiograph

Open the affected portion of the incision to allow for drainage

Insert a nasogastric tube and maintain nothing-by-mouth status

Administer intravenous furosemide and implement fluid restriction

Show answer & explanation

Answer: Open the affected portion of the incision to allow for drainage

Answer

Open the affected portion of the incision to allow for drainage

The patient's presentation of fever, erythema, induration, and a fluctuant mass at the surgical incision on postoperative day 6 is highly diagnostic of a superficial surgical site infection (SSI) complicated by an abscess. The cornerstone of management for a superficial SSI with a fluid collection is source control. The most appropriate next step is to remove the staples or sutures over the affected area to open the wound, allow for drainage of the purulent material, and pack the wound with sterile gauze. Systemic antibiotics are generally reserved for cases with significant surrounding cellulitis, deep space involvement, or systemic inflammatory response syndrome (SIRS), and they should only be given in conjunction with, not instead of, definitive drainage.

Step-by-Step Solution

Analyze the timing and clinical signs of the patient's presentation.

The patient developed fever and localized wound fluctuance on postoperative day 6.

Understanding the timeline of postoperative complications (the '5 Ws') helps isolate the likely etiology, with wound infections classically presenting between days 5 and 7.

Diagnose the specific complication based on physical examination.

The tender, erythematous, and fluctuant mass at the incision site indicates a superficial surgical site infection (SSI) complicated by an abscess.

Fluctuance represents a walled-off collection of purulent material beneath the skin.

Determine the definitive management for a superficial surgical abscess.

The most appropriate next step is bedside source control by opening the wound to drain the pus.

Antibiotics cannot effectively penetrate an abscess cavity; physical evacuation of the infected material is required for resolution.

Key Concept

Superficial surgical site infections presenting with fluctuance (abscess) require immediate source control via bedside opening, drainage, and packing as the primary intervention.

Question 7817Question →

A 45-year-old man is evaluated in the gastroenterology clinic for a 6-month history of severe, burning epigastric pain and chronic, large-volume watery diarrhea. The pain frequently awakens him at night and has not improved despite taking a high-dose proton pump inhibitor (PPI) for the past 8 weeks. Upper endoscopy performed two weeks ago revealed thickened gastric folds and multiple deep ulcerations in the stomach, duodenal bulb, and descending duodenum. Gastric biopsies obtained during the procedure were negative for Helicobacter pylori. Vital signs are within normal limits, and routine laboratory studies show a normal comprehensive metabolic panel. The physician strongly suspects a neuroendocrine etiology for this patient's condition. Arrange the following diagnostic steps in the most appropriate chronological sequence for evaluating this patient's suspected condition.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct diagnostic sequence is to first discontinue the proton pump inhibitor, then measure fasting serum gastrin, follow up with a secretin stimulation test if needed, and finally perform tumor localization imaging.

The diagnostic algorithm for Zollinger-Ellison syndrome (ZES) requires strict biochemical confirmation prior to anatomic localization. Because proton pump inhibitors (PPIs) cause a profound decrease in gastric acid, they stimulate reactive gastrin secretion from normal gastric G-cells, leading to false-positive results. Therefore, the essential first step is to discontinue the PPI. Following an appropriate washout period, a fasting serum gastrin is measured. If this level is equivocal (typically between 110 and 1,000 pg/mL) rather than definitively diagnostic (>1,000 pg/mL with gastric pH <2), a secretin stimulation test is utilized. In a normal physiologic state, secretin inhibits gastrin release; however, it paradoxically increases gastrin secretion from gastrinoma cells. Only after biochemical confirmation is definitively complete should the clinician pursue imaging, such as somatostatin receptor scintigraphy (OctreoScan) or endoscopic ultrasound (EUS), to localize the tumor for potential surgical resection.

Step-by-Step Solution

Discontinue PPI therapy.

Gastric acid secretion recovers, preventing false-positive gastrin elevation.

PPI-induced achlorhydria causes reactive hypergastrinemia, which confounds biochemical screening.

Measure fasting serum gastrin.

Provides the baseline gastrin concentration.

This is the primary biochemical screening test for Zollinger-Ellison syndrome.

Perform a secretin stimulation test.

Paradoxical rise in gastrin (>200 pg/mL) confirms the diagnosis.

Required to differentiate a gastrinoma from other causes of hypergastrinemia when initial levels are non-diagnostic (<1,000 pg/mL).

Perform tumor localization imaging (EUS or somatostatin receptor scintigraphy).

Identifies the anatomic location of the gastrinoma (often in the gastrinoma triangle).

Anatomic localization is strictly reserved until after the biochemical diagnosis is secure to avoid chasing incidental non-functioning neuroendocrine tumors.

Key Concept

The algorithmic diagnostic sequence for Zollinger-Ellison syndrome (Gastrinoma)

Question 7818Question →

A $65$ -year-old man is brought to the emergency department due to the sudden onset of severe, tearing chest pain that radiates to his back. His temperature is $37.1^\circ\text{C}$ ( $98.8^\circ\text{F}$ ), blood pressure is $210/120\text{ mmHg}$ in the right arm and $170/95\text{ mmHg}$ in the left arm, pulse is $112/\text{min}$ , and respirations are $20/\text{min}$ . Physical examination reveals a new diastolic decrescendo murmur at the right upper sternal border. A portable chest radiograph shows a widened mediastinum. Acute ascending aortic dissection is strongly suspected. Arrange the following steps in the most appropriate chronological sequence for the management of this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct management sequence is to first administer intravenous esmolol, followed by intravenous sodium nitroprusside, then obtain CT angiography of the chest, and finally proceed with emergent surgical repair.

The proper sequence for managing a hemodynamically stable (but hypertensive) patient with an acute aortic dissection is initial strict blood pressure and heart rate control, followed by diagnostic confirmation, and finally definitive surgical repair for Type A dissections. Beta-blockers (esmolol) MUST be given before vasodilators (nitroprusside) to prevent reflex tachycardia and increased ventricular contractility, both of which increase aortic wall shear stress. Once the patient is medically stabilized, CT angiography is performed to confirm the anatomy. Because this patient has a Type A dissection (indicated by the aortic regurgitation murmur and right-to-left arm pulse/pressure deficits from brachiocephalic involvement), surgery is the ultimate destination.

Step-by-Step Solution

Identify the clinical presentation as highly suspicious for an acute ascending aortic dissection.

The patient exhibits tearing chest pain, asymmetric blood pressures, a widened mediastinum, and a new murmur of aortic regurgitation.

Recognizing the life-threatening nature of the emergency dictates immediate initial stabilization rather than delaying for imaging.

Select the first-line pharmacologic stabilization.

Administer an intravenous beta-blocker (esmolol).

Beta-blockade reduces heart rate and left ventricular contractility, thereby reducing aortic wall shear stress (

dP/dt

) and preventing dissection propagation.

Select the second-line pharmacologic stabilization.

Administer an intravenous vasodilator (sodium nitroprusside).

A vasodilator is often necessary to further reduce blood pressure but must strictly follow beta-blockade to prevent compensatory reflex tachycardia.

Choose the definitive diagnostic step.

Obtain a CT angiography of the chest.

Definitive imaging is required to confirm the diagnosis and classify the dissection before taking the patient to the operating room.

Choose the definitive therapeutic step.

Proceed with emergent cardiothoracic surgery.

Stanford Type A dissections carry a very high mortality rate and require immediate surgical intervention for repair.

Key Concept

The precise sequence of anti-impulse therapy and definitive management in acute aortic dissection.

Estimated Time:1m 30s

Question 7819Question →

Paramedics bring a 72-year-old female to the resuscitation bay due to sudden and severe difficulty breathing that started in the middle of the night. The patient has a known past medical history of chronic obstructive pulmonary disease (COPD), diet-controlled type 2 diabetes mellitus, and long-standing hypertension. Upon arrival, she is sitting upright on the stretcher, visibly sweating, and speaking in one-word sentences. She states she felt like she was "drowning" when she attempted to sleep in her bed.

Vital signs reveal a temperature of $36.9^\circ$ C ( $98.4^\circ$ F), blood pressure of $172/98$ mm Hg, heart rate of $115$ /min, and respiratory rate of $30$ /min. Oxygen saturation is $84\%$ while breathing ambient air.

Physical assessment demonstrates significant use of accessory neck muscles. The neck veins are visibly distended up to $11$ cm H $_2$ O. Cardiac auscultation is notable for tachycardia and an extra diastolic heart sound shortly after S2. Pulmonary evaluation reveals bilateral widespread expiratory wheezing combined with coarse crackles extending halfway up the lung fields.

Laboratory evaluation of arterial blood drawn without supplemental oxygen demonstrates:
pH: $7.24$
PaCO $_2$ : $62$ mm Hg
PaO $_2$ : $50$ mm Hg
HCO $_3^-$ : $26$ mEq/L

A bedside chest radiograph displays a widened cardiac silhouette, prominent cephalization of pulmonary vessels, and diffuse hazy opacities in the perihilar regions bilaterally.

Which of the following is the most appropriate initial management for this patient's condition?

Intravenous bolus of a loop diuretic coupled with noninvasive ventilatory support

Intravenous methylprednisolone combined with continuous inhaled albuterol

Intravenous infusion of sodium bicarbonate to directly correct the acidemia

Intravenous vancomycin and cefepime to treat presumed atypical pneumonia

Rapid sequence intubation followed by invasive mechanical ventilation

Show answer & explanation

Answer: Intravenous bolus of a loop diuretic coupled with noninvasive ventilatory support

Answer

The most appropriate initial management is to provide an intravenous loop diuretic along with noninvasive ventilatory support.

The correct approach targets the underlying acute decompensated heart failure (ADHF) causing cardiogenic pulmonary edema. Although the patient has a history of COPD, her presentation is classic for ADHF, characterized by paroxysmal nocturnal dyspnea, elevated jugular venous pressure, an S3 gallop, and a chest radiograph showing cardiomegaly with perihilar opacities. The wheezing she exhibits is 'cardiac asthma,' caused by edema fluid compressing the bronchioles. The standard of care for severe ADHF with respiratory distress in a conscious, alert patient involves noninvasive positive-pressure ventilation (NIPPV) and intravenous loop diuretics. NIPPV reduces the work of breathing, improves oxygenation, and increases intrathoracic pressure, which favorably decreases both left ventricular preload and afterload. Loop diuretics act rapidly to reduce intravascular volume and pulmonary congestion.

Step-by-Step Solution

Analyze the clinical signs and history to establish the primary diagnosis.

The combination of orthopnea, elevated jugular venous pressure, an S3 gallop, and radiographic evidence of cardiomegaly with perihilar opacities strongly indicates acute decompensated heart failure (ADHF), despite the patient's history of COPD.

Accurate diagnosis is critical because 'cardiac asthma' (wheezing due to airway edema) can easily mimic a COPD exacerbation but requires different management.

Interpret the arterial blood gas values.

The ABG shows a primary acute respiratory acidosis (low pH of 7.24 and elevated PaCO2 of 62 mm Hg) along with severe hypoxemia.

This confirms acute hypercapnic and hypoxemic respiratory failure resulting from alveolar flooding and respiratory muscle fatigue.

Determine the optimal therapeutic interventions for ADHF with respiratory failure.

Initial treatment must include preload and afterload reduction via noninvasive positive-pressure ventilation (NIPPV) and diuresis with an intravenous loop diuretic.

NIPPV rapidly improves oxygenation, decreases the work of breathing, and favorably alters cardiopulmonary hemodynamics, while diuretics clear the excess intravascular volume.

Key Concept

Patients with acute decompensated heart failure can present with wheezing ('cardiac asthma') and respiratory acidosis; the first-line treatment in alert patients is noninvasive positive-pressure ventilation combined with intravenous loop diuretics.

Question 7820Question →

A 52-year-old man is evaluated in the clinic for an $8$ -month history of worsening fatigue, decreased libido, and a $5\text{ kg}$ ( $11\text{ lb}$ ) weight gain. He works as a delivery driver and reports recently bumping into the side mirrors of parked cars because he "did not see them in the corners of his eyes." He has no significant past medical history and takes no medications. Vital signs show a heart rate of $54/\text{min}$ and blood pressure of $110/70\text{ mm Hg}$ . Physical examination reveals a puffy face and a delayed relaxation phase of the deep tendon reflexes. Visual field testing by confrontation confirms a loss of peripheral vision bilaterally.

Laboratory results are as follows:

Laboratory Test	Result	Reference Range
Thyroid-stimulating hormone (TSH)	$1.1\text{ mU/L}$	$0.4 - 4.0\text{ mU/L}$
Free thyroxine (T4)	$0.4\text{ ng/dL}$	$0.9 - 1.7\text{ ng/dL}$
Total testosterone	$120\text{ ng/dL}$	$300 - 1000\text{ ng/dL}$
Luteinizing hormone (LH)	$1.2\text{ mIU/mL}$	$1.5 - 9.3\text{ mIU/mL}$

Which of the following best describes the underlying pathophysiology of this patient's condition?

Autoimmune destruction of the thyroid gland follicular cells

Decreased peripheral tissue conversion of thyroxine to triiodothyronine

Compression of normal pituitary tissue by a space-occupying lesion

Primary failure of the Leydig cells with aberrant feedback signaling

Autoimmune-mediated destruction of the adrenal cortex

Show answer & explanation

Answer: Compression of normal pituitary tissue by a space-occupying lesion

Answer

Compression of normal pituitary tissue by a space-occupying lesion

This patient's clinical presentation is classic for a non-functioning pituitary macroadenoma. He has symptoms of hypothyroidism (fatigue, weight gain, delayed reflex relaxation) and hypogonadism (decreased libido). The laboratory findings confirm central hypothyroidism (low Free T4 with an inappropriately normal TSH) and central hypogonadism (low testosterone with an inappropriately normal LH). Furthermore, his visual complaints describe bitemporal hemianopsia, a specific visual field defect caused by mass effect compressing the crossing nasal fibers at the optic chiasm. The underlying pathophysiology is the growth of a benign neoplasm (macroadenoma) that both compresses the optic chiasm superiorly and destroys or compresses the normal hormone-producing cells of the anterior pituitary, leading to panhypopituitarism.

Step-by-Step Solution

Interpret the clinical presentation and physical exam findings.

Fatigue, weight gain, bradycardia, and delayed reflexes suggest clinical hypothyroidism. Decreased libido suggests hypogonadism. Bumping into side mirrors indicates bitemporal hemianopsia (loss of peripheral vision).

To identify the distinct symptom clusters pointing toward specific anatomical and endocrine pathologies.

Analyze the thyroid laboratory panel.

The patient has a frankly low Free T4 with an inappropriately normal TSH.

To differentiate between primary hypothyroidism (where TSH would be elevated) and central hypothyroidism.

Evaluate the gonadal laboratory panel.

The patient has low total testosterone with an inappropriately normal/low LH.

To identify concurrent central hypogonadism, which, combined with central hypothyroidism, confirms panhypopituitarism.

Synthesize clinical and laboratory data to determine the etiology.

The combination of multiple anterior pituitary hormone deficiencies (panhypopituitarism) and optic chiasm compression (bitemporal hemianopsia) strongly indicates a pituitary macroadenoma.

To establish the underlying pathophysiological mechanism of the disease process.

Key Concept

Central hypothyroidism presents with low Free T4 and inappropriately normal or low TSH. When combined with other pituitary hormone deficiencies and bitemporal hemianopsia, it strongly suggests a compressive pituitary macroadenoma.

PreviousPage 391 / 414Next

All practice questions

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept