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A 74-year-old woman is evaluated in the intensive care unit for rapidly worsening abdominal distension and shock. She was admitted 10 days ago for community-acquired pneumonia and was treated with a 5-day course of intravenous ceftriaxone and azithromycin. Four days ago, she developed profuse, watery diarrhea and tested positive for *Clostridioides difficile* toxin. She was started on oral vancomycin therapy.

Over the past 12 hours, her diarrhea abruptly ceased, but she became increasingly lethargic and her abdomen became massively distended. She is now mechanically ventilated due to encephalopathy and shock. Her son, who is her legally appointed healthcare proxy, is at the bedside. The patient has a living will from five years ago stating she would refuse major surgery. However, her son states, "Right before she was intubated today, she explicitly told me to authorize any surgery necessary to survive this."

Temperature is 39.4°C (102.9°F), blood pressure is 78/45 mmHg (while receiving a high-dose norepinephrine infusion), and pulse is 132/min. The abdomen is tympanitic, markedly distended, and rigid, with diffuse rebound tenderness. Bowel sounds are absent.

Laboratory results:
Leukocytes: $45,000 / \text{mm}^3$ (25% band forms)
Serum lactate: $6.8 \text{ mmol/L}$
Arterial blood gas:
pH: $7.18$
pCO $_2$ : $25 \text{ mmHg}$
HCO $_3^-$ : $9 \text{ mEq/L}$

Abdominal radiograph reveals a transverse colon diameter of 11 cm with mucosal edema and loss of haustral markings. No free intraperitoneal air is visible.

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

Subtotal colectomy with end ileostomy

Administration of high-dose nasogastric vancomycin, intravenous metronidazole, and vancomycin retention enemas

Escalation of antimicrobial therapy to intravenous meropenem, vancomycin, and anidulafungin

Transition to comfort-focused care in accordance with the documented living will

Urgent colonoscopic decompression of the dilated transverse colon

Show answer & explanation

Answer: Subtotal colectomy with end ileostomy

Answer

Subtotal colectomy with end ileostomy

This patient has fulminant Clostridioides difficile colitis complicated by toxic megacolon (transverse colon > 6 cm, abrupt cessation of diarrhea, rigid abdomen) and refractory septic shock. While maximal medical management (enteral vancomycin and intravenous metronidazole) is the initial therapy for severe C. difficile, this patient exhibits absolute indications for emergent surgery: hemodynamic instability requiring vasopressors, severe lactic acidosis (lactate > 5 mmol/L), marked leukocytosis (> 35,000/mm³), and peritonitis. The standard surgical procedure of choice is a subtotal colectomy with end ileostomy, which provides source control and is life-saving. Furthermore, the son's authorization for surgery is legally and ethically valid; recent, specific verbal wishes expressed to a legally appointed proxy supersede older written advance directives.

Step-by-Step Solution

Diagnose the complication

Fulminant Clostridioides difficile colitis with toxic megacolon

Patient presents with cessation of diarrhea, massive colonic dilation (>6 cm), extreme leukocytosis, and shock after initial C. difficile diagnosis.

Assess clinical stability and surgical indications

Patient requires emergent surgery

Presence of peritonitis (rigid abdomen), refractory shock on vasopressors, and severe lactic acidosis (lactate > 5 mmol/L) indicate impending perforation and medical failure.

Evaluate the ethical constraint regarding the patient's living will

Surgery is ethically and legally authorized

Recent, specific verbal wishes expressed by a competent patient to their legally appointed proxy supersede older, conflicting written advance directives.

Select the definitive intervention

Subtotal colectomy with end ileostomy

This is the standard-of-care life-saving surgical procedure for toxic megacolon secondary to fulminant C. difficile colitis.

Key Concept

Surgical indications for fulminant C. difficile colitis (Toxic Megacolon)

Estimated Time:1m 30s

Question 7142Question →

Match each trauma patient presentation with the most appropriate immediate diagnostic test or therapeutic intervention.

Click a left item, then click its matching right item

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Answer

The presentations map to their respective interventions as follows: Patient 1 requires retrograde urethrography; Patient 2 requires CT cystography; Patient 3 requires CT of the abdomen and pelvis; Patient 4 requires pelvic angiography.

Each trauma presentation requires a specific diagnostic or therapeutic pathway based on ATLS guidelines. Urethral injury must be ruled out with a retrograde urethrogram before catheterization. Bladder injuries are evaluated with CT cystography. Renal injuries in stable patients require contrast CT. Unstable pelvic bleeding without intraperitoneal fluid requires angiography.

Step-by-Step Solution

Identify signs of urethral injury in the first patient presentation.

Blood at the meatus and a high-riding prostate are noted.

These findings contraindicate urethral catheterization until retrograde urethrography confirms the urethra is intact.

Evaluate the second patient presentation for bladder trauma.

Gross hematuria and suprapubic pain with a normal urethral meatus indicate likely bladder rupture.

Because the urethra is normal, a catheter can safely be placed to perform CT cystography to locate the bladder tear.

Assess the third patient for renal trauma.

Lower rib fractures, flank bruising, and microscopic hematuria are identified in a hemodynamically stable patient.

Hemodynamic stability allows for transport to the CT scanner for an IV contrast study to accurately stage the renal injury.

Analyze the hemodynamically unstable patient with a pelvic fracture.

Hypotension despite fluid resuscitation and a negative FAST exam are noted.

A negative FAST points to retroperitoneal hemorrhage rather than intraperitoneal bleeding, making pelvic angiography with embolization the next best step for hemorrhage control.

Key Concept

Genitourinary and Pelvic Trauma Evaluation

Question 7143Question →

A $45$ -year-old male construction worker is brought to the emergency department after a high-voltage electrical injury. He accidentally touched a live power line and was thrown to the ground. The incident occurred exactly $3\text{ hours}$ prior to his arrival at the trauma center. No intravenous fluids were administered during transport. The patient weighs $90\text{ kg}$ . On physical examination, there are deep, full-thickness burns covering his entire anterior torso and his entire right upper extremity. The remainder of his skin is unaffected. A Foley catheter is placed, yielding dark red urine. According to the Advanced Trauma Life Support (ATLS) guidelines, at what rate (in $\text{mL/hr}$ ) should intravenous lactated Ringer solution be administered over the remainder of the first 8-hour post-injury window?

Show answer & explanation

Answer: 972

Answer

972 mL/hr

The correct calculation appropriately utilizes the ATLS multiplier for electrical burns (4 mL/kg/%TBSA), divides the 24-hour total in half for the first 8-hour window, and divides that half strictly by the remaining 5 hours since the injury occurred 3 hours prior.

Step-by-Step Solution

Calculate the burned body surface area using the Rule of Nines

27% TBSA

Accurate TBSA is required for the fluid resuscitation formula. Anterior torso = 18%, right upper extremity = 9%.

Select the appropriate ATLS fluid multiplier for electrical injuries

4 mL/kg/%TBSA

High-voltage electrical burns with suspected myoglobinuria require higher fluid volumes (4 mL) to flush the kidneys compared to standard thermal burns (2 mL).

Calculate the total 24-hour fluid volume

9,720 mL

4 mL × 90 kg × 27% = 9,720 mL total for the first 24 hours.

Determine the fluid volume for the first 8-hour window

4,860 mL

Standard ATLS guidelines dictate that 50% of the calculated 24-hour fluid volume is given in the first 8 hours post-injury.

Calculate the infusion rate over the remaining hours of the first window

972 mL/hr

Because 3 hours have already elapsed since the injury, the 4,860 mL must be infused over the remaining 5 hours (4,860 / 5).

Key Concept

Fluid resuscitation for electrical burns with myoglobinuria utilizes 4 mL/kg/%TBSA, with half administered over the first 8 hours from the time of injury.

Question 7144Question →

A 68-year-old man is evaluated in the intensive care unit on his fifth day of mechanical ventilation. He originally presented with severe acute pancreatitis complicated by acute respiratory distress syndrome. Three days ago, he developed a temperature of $39.2^\circ\text{C}$ ( $102.6^\circ\text{F}$ ), increased purulent endotracheal secretions, and a new right lower lobe infiltrate on chest radiograph. He was diagnosed with ventilator-associated pneumonia and empirically started on intravenous vancomycin, cefepime, and tobramycin. Today, his temperature is $37.4^\circ\text{C}$ ( $99.3^\circ\text{F}$ ), and his oxygen requirements have decreased. The endotracheal aspirate culture from three days ago grows heavy growth ( $>10^5\text{ CFU/mL}$ ) of *Klebsiella pneumoniae*. Susceptibility testing reveals resistance to ampicillin, but susceptibility to ceftriaxone, cefepime, piperacillin-tazobactam, and meropenem. Blood cultures are negative. Which of the following is the most appropriate next step in this patient's antimicrobial management?

Discontinue vancomycin and tobramycin; change cefepime to intravenous ceftriaxone

Discontinue vancomycin and tobramycin; continue intravenous cefepime

Discontinue vancomycin and tobramycin; change cefepime to intravenous piperacillin-tazobactam

Discontinue vancomycin and tobramycin; change cefepime to intravenous meropenem

Continue intravenous vancomycin, cefepime, and tobramycin without modifications

Show answer & explanation

Answer: Discontinue vancomycin and tobramycin; change cefepime to intravenous ceftriaxone

Answer

The most appropriate step is to discontinue vancomycin and tobramycin, and change cefepime to intravenous ceftriaxone.

The correct answer demonstrates proper antimicrobial stewardship through de-escalation. The patient was appropriately started on a broad-spectrum empiric regimen (vancomycin for MRSA, cefepime and tobramycin for double anti-pseudomonal coverage) for ventilator-associated pneumonia. Now that the patient is clinically improving and culture data reveals a single pathogen (*Klebsiella pneumoniae*) that is susceptible to standard beta-lactams, the empiric regimen must be narrowed. Vancomycin and tobramycin should be discontinued because neither MRSA nor *Pseudomonas aeruginosa* was isolated. Among the susceptible beta-lactams, ceftriaxone is a third-generation cephalosporin with excellent activity against wild-type *Klebsiella pneumoniae* but lacks anti-pseudomonal activity. It is the narrowest effective agent listed. Transitioning from cefepime (a fourth-generation cephalosporin with anti-pseudomonal activity) to ceftriaxone is the optimal stewardship intervention.

Step-by-Step Solution

Evaluate the clinical trajectory and need for continued empiric therapy.

The patient's fever has resolved and oxygenation has improved, indicating clinical stability and appropriateness for antimicrobial de-escalation.

De-escalation should be performed once a patient is clinically improving and culture data becomes available.

Interpret the culture and susceptibility results.

The pathogen is Klebsiella pneumoniae, susceptible to multiple beta-lactams but not ampicillin. There is no MRSA or Pseudomonas aeruginosa present.

Identifying the specific pathogen allows for discontinuation of agents covering organisms not present in the culture.

Apply principles of antimicrobial stewardship to select definitive therapy.

Vancomycin (MRSA coverage) and tobramycin (double Gram-negative/Pseudomonal coverage) must be stopped. Cefepime must be narrowed.

Maintaining unnecessary broad-spectrum agents increases the risk of adverse effects and antimicrobial resistance.

Select the narrowest effective agent for the identified organism.

Ceftriaxone is chosen over cefepime, piperacillin-tazobactam, and meropenem.

Ceftriaxone provides targeted therapy for wild-type Klebsiella pneumoniae without exerting selective pressure for Pseudomonas or anaerobic resistance.

Key Concept

Antimicrobial stewardship dictates that empiric broad-spectrum therapy for hospital-acquired infections should be narrowed to the most targeted, definitive agent once culture and susceptibility data are available and clinical improvement is noted.

Estimated Time:2m 0s

Question 7145Question →

Match the following clinical and laboratory profiles of patients presenting with suspected hypercortisolism to their most likely underlying etiology.

Click a left item, then click its matching right item

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Answer

Profile 1 matches Pituitary ACTH-secreting adenoma; Profile 2 matches Ectopic ACTH secretion; Profile 3 matches Primary adrenal adenoma; Profile 4 matches Exogenous synthetic glucocorticoid use; Profile 5 matches Physiologic hypercortisolism.

The correct matches follow the standard endocrine diagnostic algorithm for hypercortisolism. First, true hypercortisolism must be confirmed (or refuted, as in exogenous dexamethasone use where endogenous levels are low, or pseudo-Cushing where diurnal rhythm is intact). Second, ACTH levels determine if the source is ACTH-dependent (high/normal ACTH) or ACTH-independent (suppressed ACTH, implying an adrenal source). Third, high-dose dexamethasone suppression differentiates the ACTH-dependent causes: pituitary sources (Cushing disease) typically suppress, whereas ectopic sources do not.

Step-by-Step Solution

Analyze Profile 4 which presents with paradoxical findings of Cushingoid features but low cortisol levels.

Identifies Exogenous synthetic glucocorticoid use.

Dexamethasone suppresses endogenous ACTH and cortisol but is not detected on standard cortisol assays.

Differentiate between ACTH-dependent and ACTH-independent true Cushing syndrome for Profiles 1, 2, and 3.

Profile 3 has suppressed ACTH, indicating an ACTH-independent source (Primary adrenal adenoma).

Autonomous cortisol secretion from the adrenal glands suppresses pituitary ACTH via negative feedback.

Differentiate the ACTH-dependent causes (Profiles 1 and 2) using the high-dose dexamethasone suppression test.

Profile 1 suppresses (Pituitary adenoma), while Profile 2 does not suppress (Ectopic ACTH).

Pituitary adenomas retain some negative feedback sensitivity at high dexamethasone doses, whereas ectopic sources typically lack functional glucocorticoid receptors.

Analyze Profile 5 for borderline findings in the initial screening tests.

Identifies Physiologic hypercortisolism (Pseudo-Cushing syndrome).

Normal midnight salivary cortisol indicates an intact diurnal rhythm, pointing away from pathological Cushing syndrome.

Key Concept

Diagnostic algorithm for Cushing syndrome and related hypercortisolemic states

Question 7146Question →

A 71-year-old man is evaluated on the medical ward on hospital day 3. He was initially admitted for severe community-acquired pneumonia presenting with fever, productive cough, hypoxemia, and a dense left lower lobe consolidation on a chest radiograph. At the time of admission, empiric therapy with intravenous ceftriaxone and oral azithromycin was initiated. He has shown excellent clinical improvement; his oxygen requirements have resolved, and he has been afebrile for the past 24 hours. The patient is currently tolerating a regular diet and ambulating in the hallways. Both blood and high-quality sputum cultures obtained on admission have finalized, demonstrating the growth of *Streptococcus pneumoniae*. Susceptibility testing results for the isolate are as follows:

Antimicrobial Agent	Interpretation	Minimum Inhibitory Concentration (MIC)
Penicillin	Susceptible	$0.03$ µg/mL
Amoxicillin	Susceptible	$\le 1.0$ µg/mL
Ceftriaxone	Susceptible	$0.25$ µg/mL
Levofloxacin	Susceptible	$0.5$ µg/mL
Azithromycin	Resistant	$> 8.0$ µg/mL

The patient is being prepared for discharge with a prescription to complete a 7-day total course of antibiotics. Which of the following is the most appropriate antibiotic regimen for this patient's discharge?

Oral amoxicillin

Oral amoxicillin-clavulanate

Oral levofloxacin

Oral cefpodoxime

Intravenous ceftriaxone via a peripherally inserted central catheter

Show answer & explanation

Answer: Oral amoxicillin

Answer

Oral amoxicillin

The correct response identifies that the patient requires de-escalation of his antibiotic regimen. He initially received standard empiric therapy (ceftriaxone and azithromycin) for inpatient community-acquired pneumonia. With the pathogen identified as a penicillin-susceptible strain of *Streptococcus pneumoniae*, and the patient clinically stable and tolerating oral intake, the most appropriate next step is to transition to a narrow-spectrum oral agent. High-dose oral amoxicillin effectively treats this infection while strictly adhering to antimicrobial stewardship principles.

Step-by-Step Solution

Identify the primary pathogen and analyze its susceptibility profile from the provided laboratory data.

The pathogen is Streptococcus pneumoniae, which is susceptible to penicillin (and amoxicillin), ceftriaxone, and levofloxacin, but resistant to azithromycin.

Determining the specific etiology and resistance pattern is required to tailor ongoing antimicrobial therapy away from empiric regimens.

Evaluate the patient's clinical trajectory to determine the appropriate route of administration (intravenous vs. oral).

The patient is clinically improved, afebrile, hemodynamically stable, and tolerating an oral diet, indicating he is ready for transition to oral therapy.

Early transition from intravenous to oral therapy reduces catheter-related complications, shortens hospital length of stay, and decreases healthcare costs.

Select the most appropriate oral agent based on the principles of antimicrobial stewardship.

Oral amoxicillin is the optimal choice because it provides highly effective, targeted, narrow-spectrum coverage against this specific isolate.

Using the narrowest effective spectrum minimizes collateral damage to the host microbiome and reduces the selection pressure that drives antimicrobial resistance.

Key Concept

De-escalation of empiric broad-spectrum antibiotic therapy to a targeted, narrow-spectrum agent (e.g., oral amoxicillin) is the standard of care for clinically stable patients with penicillin-susceptible Streptococcus pneumoniae pneumonia.

Estimated Time:1m 0s

Question 7147Question →

The rapid response team is urgently called to evaluate a 58-year-old male due to sudden clinical deterioration. The patient was admitted 48 hours ago with right lower lobe community-acquired pneumonia. He has a history of heart failure with preserved ejection fraction and a 30-pack-year smoking history. His admission blood cultures are currently growing *Streptococcus pneumoniae*, and he has been receiving targeted intravenous ceftriaxone.

Upon evaluation, the patient is lethargic and oriented only to person.

Vital signs are:
- Temperature: $38.6^\circ\text{C}$ ( $101.5^\circ\text{F}$ )
- Heart Rate: $122\text{/min}$
- Blood Pressure: $88/56\text{ mmHg}$
- Respiratory Rate: $34\text{/min}$
- $SpO_2$ : $84\%$ on a high-flow nasal cannula

Physical examination reveals profound use of accessory respiratory muscles. Lung auscultation demonstrates diffuse bilateral crackles and expiratory wheezing. Jugular venous pressure is normal.

Arterial blood gas analysis and relevant laboratories reveal:

Parameter	Value
$pH$	$7.15$
$PaCO_2$	$50\text{ mmHg}$
$PaO_2$	$52\text{ mmHg}$
$HCO_3^-$	$16\text{ mEq/L}$
Serum lactate	$5.2\text{ mmol/L}$

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

Perform endotracheal intubation and mechanical ventilation

Switch current antimicrobial therapy to intravenous vancomycin and cefepime

Administer an intravenous sodium bicarbonate infusion

Administer intravenous furosemide and a nitroglycerin infusion

Administer nebulized albuterol and intravenous methylprednisolone

Show answer & explanation

Answer: Perform endotracheal intubation and mechanical ventilation

Answer

The most appropriate next step is to perform endotracheal intubation and mechanical ventilation.

This patient is in distributive (septic) shock and is exhibiting clear signs of impending respiratory failure. He has severe hypoxemia (

PaO_2 = 52\text{ mmHg}

) and clinical signs of respiratory muscle fatigue (use of accessory muscles, lethargy). Furthermore, his acid-base status confirms a mixed metabolic and respiratory acidosis. He has a metabolic acidosis driven by elevated lactate (

5.2\text{ mmol/L}

). According to Winter's formula (

Expected\ PaCO_2 = 1.5 \times HCO_3^- + 8 \pm 2

), his expected

PaCO_2

should be between

30

and

34\text{ mmHg}

. His actual

PaCO_2

50\text{ mmHg}

, indicating a severe superimposed respiratory acidosis due to inadequate alveolar ventilation. Given his altered mental status (lethargy) and hemodynamic instability, noninvasive positive pressure ventilation is strictly contraindicated, making definitive airway management via endotracheal intubation the most critical next step.

Step-by-Step Solution

Evaluate the patient's clinical status and vital signs.

The patient is lethargic, hypotensive, hypoxemic, and using accessory muscles, indicating septic shock and impending respiratory failure.

Recognizing the signs of respiratory muscle fatigue and altered mental status is critical for determining the urgency of airway intervention.

Analyze the arterial blood gas using Winter's formula to determine the acid-base disorder.

The patient has a primary metabolic acidosis (

HCO_3^-

16\text{ mEq/L}

). Expected

PaCO_2

(1.5 \times 16) + 8 \pm 2 = 32 \pm 2\text{ mmHg}

. Since the actual

PaCO_2

50\text{ mmHg}

, there is a severe concurrent respiratory acidosis.

Identifying the mixed acid-base disorder confirms that the patient's respiratory drive is failing to compensate, necessitating mechanical support.

Select the appropriate method of respiratory support.

Invasive mechanical ventilation via endotracheal intubation is selected.

Non-invasive positive pressure ventilation (NIPPV) is contraindicated due to the patient's lethargy (inability to protect the airway) and hemodynamic instability.

Key Concept

Impending respiratory failure characterized by altered mental status, hypoxemia, and mixed metabolic and respiratory acidosis requires immediate endotracheal intubation.

Question 7148Question →

A previously healthy college student evaluates at the university health clinic reporting sharp, stabbing chest pain that started the day before. The discomfort is severely aggravated by lying flat in bed and taking deep breaths, but provides significant relief when the patient is sitting up and leaning forward. Vital signs reveal a temperature of 38.1°C (100.6°F), heart rate of 98/min, and blood pressure of 118/74 mm Hg. An electrocardiogram demonstrates diffuse, concave ST-segment elevations and PR-segment depressions across most limb and precordial leads. Cardiac troponin levels are within normal limits. Which of the following is the most appropriate initial pharmacological treatment for this patient's condition?

Nonsteroidal anti-inflammatory drugs and colchicine

Dual antiplatelet therapy and a high-dose statin

Intravenous loop diuretics and strict fluid restriction

Inhaled short-acting beta-agonists and oral glucocorticoids

Broad-spectrum intravenous antibiotics

Show answer & explanation

Answer: Nonsteroidal anti-inflammatory drugs and colchicine

Answer

Nonsteroidal anti-inflammatory drugs and colchicine

The correct treatment is the combination of nonsteroidal anti-inflammatory drugs (NSAIDs) and colchicine. The patient's clinical presentation of sharp, pleuritic chest pain that improves with leaning forward, combined with diffuse ST-segment elevations and PR-segment depressions on an electrocardiogram, is classic for acute pericarditis. The standard first-line therapy for idiopathic or viral acute pericarditis consists of NSAIDs (such as ibuprofen or indomethacin) for symptom relief and inflammation reduction, alongside colchicine, which is critical for preventing recurrent episodes.

Step-by-Step Solution

Evaluate the clinical presentation and physical exam findings.

The patient has pleuritic, positional chest pain (worse lying flat, better leaning forward) accompanied by a low-grade fever.

These historical features are highly specific and classic for acute pericarditis.

Analyze the electrocardiogram findings.

The tracing shows diffuse ST-segment elevations and PR-segment depressions.

This ECG pattern is pathognomonic for acute pericarditis, helping to distinguish it from the localized ST elevations typical of an acute myocardial infarction.

Determine the appropriate initial pharmacological therapy.

Nonsteroidal anti-inflammatory drugs (NSAIDs) combined with colchicine.

This dual therapy reduces acute pericardial inflammation, relieves symptoms, and significantly decreases the risk of recurrent disease.

Key Concept

Diagnosis and initial pharmacological management of acute pericarditis.

Question 7149Question →

A 30-year-old man is brought to the emergency department after a fall from a height of 6 meters (20 feet). He is confused and agitated. His temperature is 36.8°C (98.2°F), blood pressure is 75/40 mm Hg, and pulse is 135/min. Primary survey reveals a patent airway and clear, equal breath sounds bilaterally. A focused assessment with sonography for trauma (FAST) examination is negative for intraperitoneal or pericardial fluid. Pelvic examination shows stability to anteroposterior and lateral compression, and a portable anteroposterior pelvic radiograph is normal. Examination of the left lower extremity reveals a visibly deformed, shortened thigh with tense swelling. There are no open wounds. Distal pulses are palpable but diminished in the left foot compared to the right. Which of the following is the most appropriate next step in management?

Transport the patient to the radiology suite for a computed tomography (CT) scan of the abdomen and lower extremity

Administer broad-spectrum intravenous antibiotics such as vancomycin and piperacillin-tazobactam

Initiate intravenous fluid resuscitation and apply a traction splint to the left lower extremity

Delay immediate interventions to identify and contact a legally appointed surrogate decision-maker for consent

Administer intravenous furosemide to rapidly decrease the tense swelling in the left thigh

Show answer & explanation

Answer: Initiate intravenous fluid resuscitation and apply a traction splint to the left lower extremity

Answer

Initiate intravenous fluid resuscitation and apply a traction splint to the left lower extremity

This patient is presenting with hemorrhagic shock resulting from a closed femoral shaft fracture. In the setting of trauma, a patient with hypotension, tachycardia, and altered mental status is presumed to have hemorrhagic shock until proven otherwise. The major areas where a patient can bleed enough to cause shock are the chest, abdomen, pelvis, and thighs (long bones). With a negative FAST exam, normal pelvic radiograph, and clear breath sounds, the internal hemorrhage is localized to the visibly deformed and swollen left thigh. A fractured femur can easily conceal 1,000 to 2,000 mL of blood loss. The most appropriate immediate management is to initiate intravenous fluid (and likely blood) resuscitation while simultaneously applying a traction splint. Traction splinting pulls the limb out to length, which geometrically decreases the volume of the thigh compartment. This helps to tamponade the bleeding, stabilize the fracture fragments, and provide significant pain relief before definitive surgical fixation.

Step-by-Step Solution

Assess the patient's hemodynamic status based on vital signs.

The patient is in hemorrhagic shock, evidenced by a blood pressure of 75/40 mm Hg, heart rate of 135/min, and confusion.

Recognizing shock is the first step in trauma management to prioritize life-saving interventions over definitive diagnostic imaging.

Identify the source of the hemorrhage using the primary survey and adjuncts.

The chest, abdomen, and pelvis have been ruled out as major sources of bleeding (clear breath sounds, negative FAST, stable normal pelvis). The tense, deformed left thigh points to a femoral shaft fracture.

A single closed femur fracture can result in 1 to 2 liters of internal blood loss into the thigh compartment, which is sufficient to cause severe shock.

Determine the appropriate acute intervention for a bleeding femur fracture.

The patient requires immediate volume resuscitation and the application of a traction splint.

A traction splint restores anatomical bone length, which reduces the cylindrical volume of the thigh compartment. This increases the internal tissue pressure and helps to tamponade the bleeding vessels.

Key Concept

Management of hemorrhagic shock secondary to a closed femoral shaft fracture using a traction splint

Estimated Time:1m 15s

Question 7150Question →

A 71-year-old woman is evaluated in the emergency department due to the acute onset of severe, unremitting groin pain accompanied by nausea and green-colored emesis over the past 8 hours. She also reports a failure to pass gas or stool since yesterday. Her temperature is 38.5°C (101.3°F), pulse is 118/min, and blood pressure is 95/60 mm Hg. Physical examination reveals a moderately distended abdomen. High-pitched, tinkling bowel sounds are auscultated. Below the right inguinal ligament and medial to the femoral artery pulsation, there is a 3-cm, tense, exquisitely tender mass. The skin overlying the mass appears erythematous and slightly violaceous. The mass cannot be pushed back into the abdominal cavity. Laboratory analysis is notable for a leukocyte count of 17,000/mm³ and a serum lactate concentration of 4.2 mmol/L. Which of the following is the most appropriate next step in the management of this patient?

Urgent operative intervention

Manual reduction of the mass under procedural sedation

CT scan of the abdomen and pelvis with contrast

Intravenous broad-spectrum antimicrobial therapy and clinical observation

Continued nasogastric decompression and serial physical examinations

Show answer & explanation

Answer: Urgent operative intervention

Answer

The correct response is urgent operative intervention, as the patient has clinical signs of a strangulated femoral hernia.

The correct approach specifies immediate surgery. This patient presents with a small bowel obstruction secondary to a strangulated femoral hernia. The irreducible, exquisitely tender mass with overlying erythema, combined with systemic signs of inflammation and ischemia (fever, leukocytosis, elevated serum lactate), strongly suggests compromised bowel perfusion. This is a surgical emergency that requires immediate operative exploration to release the obstruction and assess bowel viability.

Step-by-Step Solution

Identify the primary clinical problem from the physical examination findings.

The patient has a tender, erythematous, irreducible groin mass below the inguinal ligament, representing an incarcerated femoral hernia causing bowel obstruction.

Accurate identification of the mass determines the etiology of the patient's gastrointestinal symptoms.

Evaluate for complications associated with the hernia.

The presence of fever, tachycardia, skin discoloration, leukocytosis, and elevated lactate indicates strangulation and bowel ischemia.

Distinguishing between a simple incarcerated hernia and a strangulated hernia dictates the urgency and type of treatment.

Select the appropriate management strategy based on the complication.

Urgent operative intervention is chosen over conservative measures, imaging, or manual reduction.

Strangulated bowel is a surgical emergency requiring immediate release of the constriction and potential resection of necrotic tissue.

Key Concept

Strangulated hernias present with signs of bowel obstruction, systemic toxicity, and an irreducible, painful mass with overlying skin changes, necessitating immediate surgical exploration.

Question 7151Question →

A patient receiving cytotoxic chemotherapy for acute myeloid leukemia arrives at the oncology triage unit reporting severe chills and a recorded temperature of $38.8^\circ\text{C}$ ( $101.8^\circ\text{F}$ ). Her blood pressure is $100/60\text{ mm Hg}$ , and her heart rate is $112/\text{min}$ . She has an indwelling totally implantable venous access device. Laboratory analysis reveals an absolute neutrophil count of $350/\text{mm}^3$ .

Arrange the following interventions in the most appropriate sequential order for managing this patient's condition according to standard clinical guidelines for high-risk febrile neutropenia.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: Obtain blood cultures, administer empiric antipseudomonal beta-lactam therapy, reassess clinical response at 48-72 hours, and finally add empiric antifungal therapy if fever persists after 4-7 days.

High-risk febrile neutropenia is an infectious disease emergency. The standard sequence of care dictates immediately drawing blood cultures to identify the pathogen, followed promptly (within 60 minutes) by empiric broad-spectrum antibiotics with antipseudomonal activity. Once stabilized, the patient is reassessed at 48 to 72 hours when preliminary microbiological data is available. If the patient remains persistently febrile and profoundly neutropenic for 4 to 7 days despite appropriate antibacterial therapy, an occult invasive fungal infection is highly suspected, warranting the sequential addition of empiric antifungal coverage.

Step-by-Step Solution

Identify the clinical emergency

The patient has high-risk febrile neutropenia (absolute neutrophil count <

500/\text{mm}^3

and fever).

Recognizing the condition dictates the extreme urgency of diagnostic and therapeutic interventions.

Prioritize initial diagnostic testing

Blood cultures are drawn from both the central port and a peripheral site as the first active intervention.

Crucial to capture the pathogen before antibacterial agents alter microbiological viability.

Initiate empiric pharmacotherapy

Intravenous antipseudomonal beta-lactam therapy is administered immediately after cultures are drawn.

Delays in antibiotic administration significantly increase mortality in neutropenic patients; it is a time-sensitive emergency.

Plan sequential follow-up and escalation

Reassessment occurs at 48 to 72 hours, with potential addition of empiric antifungals at 4 to 7 days if fever persists.

Aligns with expected microbiological turnaround times and the known timeline for secondary invasive fungal infections.

Key Concept

Chronological management of high-risk febrile neutropenia

Question 7152Question →

A 24-year-old man is brought to the emergency department after a high-speed collision while snowboarding, during which he struck a tree. On arrival, he is confused and complains of severe abdominal pain. His temperature is 36.5°C (97.7°F), blood pressure is 82/45 mmHg, pulse is 134/min, and respirations are 24/min. Pulse oximetry is 96% on room air. Primary survey reveals a patent airway and clear breath sounds bilaterally. Cardiac auscultation shows a rapid, regular rhythm with no murmurs. The abdomen is distended with diffuse tenderness, guarding, and rebound tenderness. Examination of the pelvis reveals stability to anteroposterior and lateral compression. Intravenous access is established, and the patient receives 1 L of warmed lactated Ringer solution, after which his blood pressure is 86/48 mmHg and pulse is 128/min. A bedside focused assessment with sonography for trauma (FAST) demonstrates a significant amount of anechoic fluid in the splenorenal and hepatorenal recesses. Which of the following is the most appropriate next step in management?

Computed tomography of the abdomen and pelvis

Diagnostic peritoneal lavage

Exploratory laparotomy

Angiography with therapeutic embolization

Diagnostic laparoscopy

Show answer & explanation

Answer: Exploratory laparotomy

Answer

Exploratory laparotomy

The correct management for this patient is immediate surgical exploration. The patient has sustained blunt abdominal trauma (BAT) and is in hemorrhagic shock, evidenced by persistent hypotension and tachycardia despite an initial fluid challenge. In the setting of BAT, a bedside ultrasound (FAST) is used to rapidly identify free intraperitoneal fluid (blood). When a patient is hemodynamically unstable and has a positive FAST examination, the diagnosis of life-threatening intra-abdominal hemorrhage is established. The absolute next best step is an emergency exploratory laparotomy to achieve surgical source control. Any delay for further diagnostic testing increases mortality.

Step-by-Step Solution

Assess hemodynamic status

The patient remains hypotensive (86/48 mmHg) and tachycardic (128/min) despite initial crystalloid resuscitation.

Hemodynamic instability dictates the urgency and type of subsequent interventions in trauma protocols.

Evaluate the mechanism of injury and primary survey findings

Blunt abdominal trauma with a stable pelvis and no signs of intrathoracic hemorrhage or tension pneumothorax.

Localizes the likely source of hemorrhagic shock to the abdominal cavity.

Interpret the bedside ultrasound (FAST) results

Positive for anechoic fluid in the splenorenal and hepatorenal recesses, indicating hemoperitoneum.

Confirms the abdomen as the source of life-threatening internal hemorrhage.

Determine the definitive management

Immediate transfer to the operating room for surgical exploration.

A hemodynamically unstable patient with confirmed intraperitoneal bleeding requires emergency surgical source control without further diagnostic delay.

Key Concept

Hemodynamically unstable patients with blunt abdominal trauma and a positive FAST examination require immediate exploratory laparotomy.

Estimated Time:1m 30s

Question 7153Question →

A 58-year-old man with a history of diet-controlled type 2 diabetes mellitus is evaluated in the hospital on day 3 of admission. He initially presented with progressive left lower quadrant abdominal pain, nausea, and low-grade fever. Computed tomography of the abdomen and pelvis demonstrated inflammation of the sigmoid colon with surrounding fat stranding, consistent with acute uncomplicated diverticulitis. He was admitted and started on empiric intravenous piperacillin-tazobactam. Currently, his temperature is 37.1°C (98.8°F), his abdominal pain has largely resolved, and he is tolerating a regular diet. Blood cultures drawn on admission have grown *Escherichia coli* and *Bacteroides fragilis*. Susceptibility testing reveals that both isolates are susceptible to amoxicillin-clavulanate, ertapenem, and piperacillin-tazobactam. The *E. coli* isolate demonstrates high-level resistance to ciprofloxacin and levofloxacin. Based on these findings, which of the following is the most appropriate next step in pharmacotherapy?

Transition to oral amoxicillin-clavulanate

Transition to oral ciprofloxacin and metronidazole

Continue intravenous piperacillin-tazobactam

Transition to oral cephalexin and metronidazole

Add intravenous vancomycin to the current regimen

Show answer & explanation

Answer: Transition to oral amoxicillin-clavulanate

Answer

The most appropriate next step is to transition the patient to oral amoxicillin-clavulanate.

The correct answer utilizes optimal antimicrobial stewardship principles. The patient has met the clinical criteria for IV-to-PO conversion (afebrile, tolerating diet, hemodynamically stable). The culture data definitively rules out the use of a fluoroquinolone-based regimen due to resistance. Amoxicillin-clavulanate is available in an oral formulation, covers both the isolated Gram-negative and anaerobic bacteria, and is explicitly listed as susceptible on the panel. Transitioning to this drug allows for safe, effective outpatient completion of therapy.

Step-by-Step Solution

Assess the patient's current clinical trajectory.

The patient is afebrile, his pain has resolved, and he is tolerating oral intake.

These are the criteria for transitioning from intravenous to oral antibiotics and preparing for hospital discharge.

Analyze the microbiologic and susceptibility data provided.

Cultures show *E. coli* and *B. fragilis*. The *E. coli* is resistant to fluoroquinolones but susceptible to amoxicillin-clavulanate.

Antimicrobial therapy must be de-escalated and targeted based on objective susceptibility profiles to prevent resistance.

Select the narrowest, most effective oral regimen.

Oral amoxicillin-clavulanate covers both organisms effectively based on the lab data.

It acts as a potent, single-agent oral therapy, replacing the need for a broad-spectrum intravenous drug or a multi-drug regimen.

Key Concept

In patients recovering from intra-abdominal infections (like diverticulitis), prompt transition to narrow-spectrum oral antibiotics guided by specific culture and susceptibility data is essential for effective antimicrobial stewardship.

Question 7154Question →

A $20$ -year-old woman is brought to the emergency department by her roommate due to confusion, nausea, and ringing in her ears that began several hours ago. The roommate found an empty bottle of an over-the-counter analgesic in their shared bathroom. The patient has a medical history of major depressive disorder. Her temperature is $38.0^\circ$ C ( $100.4^\circ$ F), blood pressure is $112/70$ mm Hg, pulse is $114$ /min, and respirations are $28$ /min. She appears agitated and is breathing deeply and rapidly. Arterial blood gas on room air and serum chemistry results are as follows:

Laboratory Parameter	Result
$pH$	$7.44$
$PaCO_2$	$16$ mm Hg
$PaO_2$	$98$ mm Hg
Sodium ( $Na^+$ )	$140$ mEq/L
Potassium ( $K^+$ )	$3.6$ mEq/L
Chloride ( $Cl^-$ )	$104$ mEq/L
Bicarbonate ( $HCO_3^-$ )	$10$ mEq/L
Blood urea nitrogen	$16$ mg/dL
Creatinine	$0.8$ mg/dL

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

Mixed primary high anion gap metabolic acidosis and primary respiratory alkalosis

Primary high anion gap metabolic acidosis with appropriate respiratory compensation

Primary respiratory alkalosis with appropriate metabolic compensation

Mixed primary normal anion gap metabolic acidosis and primary respiratory alkalosis

Primary high anion gap metabolic acidosis and concurrent primary respiratory acidosis

Show answer & explanation

Answer: Mixed primary high anion gap metabolic acidosis and primary respiratory alkalosis

Answer

Mixed primary high anion gap metabolic acidosis and primary respiratory alkalosis

The correct answer accurately identifies two independent primary acid-base disorders using systematic calculation. First, the anion gap is

26

mEq/L (

140 - [104 + 10]

), which defines a high anion gap metabolic acidosis. Second, applying Winter's formula (

1.5 \times 10 + 8 = 23 \pm 2

mm Hg) reveals that adequate respiratory compensation should result in a

PaCO_2

between

21

and

25

mm Hg. Because the patient's actual

PaCO_2

16

mm Hg, she is 'blowing off' more

CO_2

than expected, proving a concurrent primary respiratory alkalosis. This mixed picture, along with tinnitus and hyperthermia, is the hallmark of salicylate toxicity.

Step-by-Step Solution

Calculate the Anion Gap to determine the presence and type of metabolic acidosis.

AG = Na^+ - (Cl^- + HCO_3^-) = 140 - (104 + 10) = 26

mEq/L.

An elevated anion gap (

>12

mEq/L) establishes the presence of a primary high anion gap metabolic acidosis (HAGMA).

Calculate the expected respiratory compensation for the metabolic acidosis using Winter's formula.

Expected

PaCO_2 = 1.5 \times HCO_3^- + 8 \pm 2 = (1.5 \times 10) + 8 = 23 \pm 2

mm Hg (Range:

21-25

mm Hg).

This determines if the change in

PaCO_2

is purely compensatory or if there is a secondary respiratory acid-base disorder.

Compare the actual

PaCO_2

to the expected

PaCO_2

calculated from Winter's formula.

Actual

PaCO_2

(

16

mm Hg) is less than the expected range (

21-25

mm Hg).

Because the patient is hyperventilating more than expected for her level of metabolic acidosis, there is a concurrent primary respiratory alkalosis.

Calculate the Delta Ratio to check for a third hidden disorder.

\Delta AG = 26 - 12 = 14

\Delta HCO_3^- = 24 - 10 = 14

. Ratio =

14/14 = 1.0

A ratio of

1.0

confirms a pure high anion gap metabolic acidosis with no hidden normal anion gap acidosis or metabolic alkalosis.

Key Concept

Salicylate toxicity classically presents with a mixed acid-base disorder: a primary respiratory alkalosis (due to direct stimulation of the medullary respiratory center) and a primary high anion gap metabolic acidosis (due to uncoupling of oxidative phosphorylation and accumulation of organic acids).

Estimated Time:2m 0s

Question 7155Question →

A 60-year-old man suddenly collapses in the hospital cafeteria. You are the first healthcare provider on the scene. Arrange the following initial steps of Basic Life Support (BLS) in the correct chronological order for managing this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence begins with assessing responsiveness, followed by calling for help and activating the emergency response, checking for a pulse and breathing, initiating CPR with chest compressions, and finally applying an AED as soon as it arrives.

According to standard Basic Life Support (BLS) guidelines for healthcare providers, the correct sequence for managing a sudden collapse is structured to minimize delays to definitive care. First, verify scene safety and check for responsiveness. If the patient is unresponsive, immediately activate the emergency response system and call for an AED. Next, simultaneously check for a pulse and normal breathing for no more than 10 seconds. If no pulse is detected, immediately begin high-quality CPR starting with chest compressions (C-A-B sequence). Finally, apply the AED as soon as it is available to analyze the rhythm and deliver a shock if indicated.

Step-by-Step Solution

Assess responsiveness

Confirms the patient is unresponsive

Prevents unnecessary interventions on a conscious person who may have simply stumbled.

Activate the emergency response system

Summons additional personnel and an AED

Early access to advanced care and defibrillation significantly improves survival rates.

Check pulse and breathing

Identifies the presence of cardiac arrest

Determines whether chest compressions or rescue breathing alone are required.

Start CPR (compressions first)

Mechanically circulates oxygenated blood

Maintains vital organ perfusion until definitive treatment can be applied.

Apply the AED

Analyzes the cardiac rhythm

Early defibrillation is the definitive treatment for ventricular fibrillation or pulseless ventricular tachycardia.

Key Concept

Basic Life Support (BLS) sequence for adult cardiac arrest

Question 7156Question →

A 62-year-old male is brought to the emergency department with a 2-day history of severe right upper quadrant abdominal pain, fever, and yellowing of his skin. In the triage area, he becomes increasingly lethargic and confused. Vital signs show a temperature of 39.2°C (102.6°F), blood pressure of 86/50 mmHg, pulse of 118/min, and respirations of 22/min. Physical examination reveals pronounced scleral icterus and right upper quadrant tenderness with involuntary guarding. Laboratory studies show a leukocyte count of 18,500/mm³, total bilirubin of 6.8 mg/dL, direct bilirubin of 5.1 mg/dL, and alkaline phosphatase of 480 U/L.

Arrange the following management steps in the most appropriate chronological order for this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is to first resuscitate with fluids and antibiotics, then perform an abdominal ultrasound, followed by ERCP for biliary decompression, and finally schedule an elective laparoscopic cholecystectomy.

The patient's presentation of fever, jaundice, right upper quadrant pain, hypotension, and altered mental status represents Reynolds pentad, indicating severe ascending cholangitis with septic shock. The universally accepted management protocol dictates that hemodynamic stabilization and broad-spectrum intravenous antibiotics are the absolute first priorities to reduce mortality. Once the patient is hemodynamically supported, a right upper quadrant ultrasound is the preferred initial diagnostic test to confirm biliary dilation and locate the obstruction. After confirmation, urgent Endoscopic Retrograde Cholangiopancreatography (ERCP) is indicated to definitively decompress the infected biliary tree. Finally, once the patient has fully recovered from the acute episode, an elective laparoscopic cholecystectomy is performed to prevent future gallstone-related complications.

Step-by-Step Solution

Identify the primary clinical syndrome.

The patient exhibits Charcot's triad (fever, jaundice, right upper quadrant pain) plus hypotension and altered mental status.

These five findings constitute Reynolds pentad, which is pathognomonic for severe acute ascending cholangitis complicated by septic shock.

Determine the immediate life-saving intervention.

Intravenous crystalloid resuscitation and broad-spectrum antibiotics are initiated.

In severe sepsis, restoring tissue perfusion and initiating antimicrobial therapy takes absolute priority over diagnostic imaging or definitive procedural interventions.

Select the best initial diagnostic modality.

Right upper quadrant abdominal ultrasound is performed.

Ultrasound is the most appropriate initial, non-invasive imaging test to confirm common bile duct dilation and detect choledocholithiasis rapidly.

Determine the definitive acute treatment.

Endoscopic retrograde cholangiopancreatography (ERCP) is conducted.

ERCP allows for urgent decompression of the infected biliary tree and extraction of the obstructing stone, which is the definitive treatment for the acute ascending cholangitis episode.

Formulate a long-term preventive plan.

Elective laparoscopic cholecystectomy is planned.

Removing the gallbladder prevents the formation of future stones, thereby eliminating the risk of recurrent cholangitis or gallstone pancreatitis.

Key Concept

The management sequence for severe acute ascending cholangitis (Reynolds pentad) prioritizes hemodynamic stabilization and broad-spectrum antibiotics, followed by diagnostic imaging, urgent biliary decompression via ERCP, and eventual elective cholecystectomy.

Question 7157Question →

A 25-year-old medical student is reviewing post-exposure prophylaxis protocols for various infectious disease scenarios. Which prophylactic regimen is most appropriate for each of the following patient exposures?

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct matches align specific infectious exposures with their targeted prophylactic guidelines: Lyme disease exposure requires single-dose doxycycline; HIV requires a 3-drug ART regimen for four weeks; meningococcal exposure requires single-dose ciprofloxacin; a tetanus-prone wound in an unvaccinated patient requires vaccine plus immunoglobulin; and a rabies exposure in an unvaccinated patient requires vaccine plus immunoglobulin.

Each clinical scenario presents a high-risk infectious exposure that warrants immediate, targeted post-exposure prophylaxis to prevent disease transmission or activation. The matching pairs reflect current standard-of-care guidelines for Lyme disease, HIV, meningococcal disease, tetanus, and rabies.

Step-by-Step Solution

Analyze the mechanism of exposure and the suspected pathogen.

Pathogens identified: Borrelia burgdorferi, HIV, Neisseria meningitidis, Clostridium tetani, and Rabies virus.

Accurate pathogen identification dictates the specific prophylactic agent required.

Assess the patient's baseline immune status or symptom profile in the vignette.

Patients are noted as asymptomatic, unvaccinated, or immunologically naive to the specific pathogen.

Vaccination status determines whether passive immunization (immunoglobulins) must be added to active immunization.

Select the guideline-concordant preventive regimen.

Appropriate antimicrobials or immunizations are assigned to each high-risk exposure.

Following current post-exposure prophylaxis guidelines minimizes the risk of progression to active clinical disease.

Key Concept

Post-Exposure Prophylaxis (PEP) in Infectious Diseases

Estimated Time:2m 0s

Question 7158Question →

A physician evaluates a 64-year-old female patient in the emergency department. She presents with sudden-onset right-sided chest pain that worsens with deep inspiration, accompanied by progressive shortness of breath over the past two hours. The patient underwent an uncomplicated right total hip arthroplasty seven days ago and has been recovering at a local rehabilitation facility. Her past medical history is significant for obesity and essential hypertension. Her current temperature is 37.8 C (100.0 F), blood pressure is 112/68 mmHg, pulse is 118/min, and respiratory rate is 26/min. Pulse oximetry shows 89% on room air. Physical examination reveals clear lung fields bilaterally. The right lower extremity demonstrates mild non-pitting edema and tenderness in the calf muscles. An electrocardiogram demonstrates sinus tachycardia. Which of the following are the most appropriate immediate steps in the management of this patient? (Select all that apply)

Select all that apply

Initiate an empiric continuous infusion of unfractionated heparin

Obtain a computed tomography angiogram of the pulmonary arteries

Administer intravenous furosemide

Initiate intravenous piperacillin-tazobactam and vancomycin

Obtain blood cultures and a urinalysis before initiating further therapies

Show answer & explanation

Answer: Initiate an empiric continuous infusion of unfractionated heparin; Obtain a computed tomography angiogram of the pulmonary arteries

Answer

Initiate an empiric continuous infusion of unfractionated heparin AND Obtain a computed tomography angiogram of the pulmonary arteries.

The correct sequence of actions involves both initiating an empiric continuous infusion of unfractionated heparin and obtaining a computed tomography angiogram of the pulmonary arteries. The patient's presentation of sudden-onset pleuritic chest pain, hypoxia, tachycardia, and unilateral calf swelling one week following major pelvic/orthopedic surgery strongly suggests an acute pulmonary embolism (PE). Because she has a high pretest probability for PE (per Wells criteria), clinical guidelines mandate that systemic anticoagulation be initiated immediately—prior to diagnostic imaging—to prevent further thrombus propagation and reduce mortality, provided there are no absolute contraindications. Simultaneously, computed tomography pulmonary angiography (CTPA) should be ordered as it is the most sensitive and specific non-invasive diagnostic test to confirm the presence of a pulmonary embolus.

Step-by-Step Solution

Analyze the clinical presentation and timeline.

The patient has sudden pleuritic chest pain, hypoxia, clear lungs, and unilateral leg swelling seven days after major orthopedic surgery.

Identifying the timing and specific combination of symptoms establishes a high clinical suspicion (high pretest probability) for venous thromboembolism (DVT progressing to PE).

Determine the need for immediate empiric treatment.

Empiric anticoagulation (e.g., unfractionated heparin) is selected.

In patients with a high pretest probability for acute PE and no contraindications, mortality is reduced by starting systemic anticoagulation immediately, rather than waiting for diagnostic confirmation.

Select the appropriate diagnostic imaging.

Computed tomography angiography (CTA) of the pulmonary arteries is ordered.

CTA is the gold-standard and most appropriate initial imaging test to definitively diagnose a pulmonary embolism in a hemodynamically stable patient with abnormal oxygenation.

Key Concept

Management of acute pulmonary embolism in the postoperative period requires simultaneous empiric systemic anticoagulation and diagnostic confirmation with computed tomography pulmonary angiography in patients with high pretest probability.

Question 7159Question →

A 22-year-old collegiate athlete is brought to the emergency department immediately after sustaining a severe hyperextension injury to his left leg during a rugby match. He is in agonizing pain. On physical examination, there is a gross step-off deformity at the left knee joint. The left foot is cold and pale. The dorsalis pedis and posterior tibial pulses are absent on the left side but are robust on the right. Capillary refill time in the left toes is delayed at 5 seconds. Assuming evidence of arterial compromise persists throughout the initial evaluation, arrange the following management steps in the most appropriate sequential order.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequential order is to first perform emergent closed reduction, followed by a post-reduction neurovascular assessment (including ABI), then obtain CT angiography, and finally proceed with operative vascular repair.

Knee dislocations (tibiofemoral dislocations) are high-energy injuries notorious for causing popliteal artery damage due to the artery's tethered anatomical course. When a patient presents with a dislocated knee and a pulseless, ischemic limb, the absolute first step is emergent bedside closed reduction. Delaying reduction for X-rays is contraindicated because it prolongs limb ischemia. After reduction, the physician must reassess the vascular status with an ankle-brachial index (ABI). If the ABI is

< 0.9

or pulses remain asymmetrical, CT angiography is indicated to localize the vascular injury. Finally, the patient is taken to the operating room for definitive vascular exploration and repair.

Step-by-Step Solution

Identify the critical emergency in the clinical presentation.

The patient has a clinically obvious knee dislocation accompanied by hard signs of vascular compromise (absent pulses, cold and pale foot, delayed capillary refill).

Recognizing limb-threatening ischemia dictates the urgency of the next interventions.

Determine the immediate intervention to restore perfusion.

Select emergent closed reduction without waiting for plain radiographs.

The popliteal artery is tightly tethered across the knee joint; prolonged dislocation causes traction and ischemia. Immediate reduction is required to potentially restore blood flow.

Determine the next step after the limb is anatomically realigned.

Select post-reduction neurovascular examination and measurement of the ankle-brachial index (ABI).

Vascular status often changes after reduction. It is mandatory to document whether perfusion has returned or if occult injury persists.

Determine the appropriate diagnostic test for persistent ischemia.

Select computed tomography (CT) angiography of the lower extremity.

Since the premise states vascular compromise persists, advanced imaging is necessary to map the presumed popliteal artery injury.

Identify the definitive management.

Select operative vascular exploration and repair.

A mapped arterial injury causing limb ischemia requires surgical repair to salvage the leg.

Key Concept

In the setting of a joint dislocation with hard signs of vascular compromise, immediate closed reduction takes precedence over obtaining baseline imaging to minimize ischemic time.

Estimated Time:1m 30s

Question 7160Question →

A 45-year-old woman is newly diagnosed with highly active rheumatoid arthritis. She presents with symmetric swelling of her metacarpophalangeal and proximal interphalangeal joints, along with 2 hours of morning stiffness. Radiographs show early marginal erosions. Assuming an inadequate clinical response to each preceding step over several months, arrange the following interventions in the standard sequential order of therapy escalation for the management of her disease.

Drag items to arrange them in the correct order

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Answer

The optimal sequence begins with conventional synthetic DMARDs (methotrexate), progresses to the addition of a biologic DMARD (TNF inhibitor), switches to a non-TNF biologic or targeted synthetic DMARD if the first biologic fails, and ultimately reserves surgical intervention for irreversible, end-stage joint destruction.

The standard of care for rheumatoid arthritis escalation follows a logical progression from broad conventional immunosuppression (methotrexate) to targeted biologic agents (TNF inhibitors), followed by alternative targeted mechanisms (non-TNF biologics or JAK inhibitors) if primary resistance occurs, and ends with surgical correction if irreversible structural damage ensues.

Step-by-Step Solution

Identify the initial pharmacologic treatment for a new diagnosis of active rheumatoid arthritis.

Methotrexate is selected as the first-line conventional synthetic DMARD.

Guidelines universally recommend early initiation of methotrexate to slow disease progression, often with bridging glucocorticoids for rapid relief.

Determine the next step when the initial conventional DMARD fails to achieve disease control.

A biologic DMARD, most commonly a TNF inhibitor, is added to the regimen.

Adding a TNF inhibitor significantly improves clinical response and radiographic outcomes in methotrexate-refractory patients.

Identify the protocol for a patient failing their first biologic agent.

Therapy is switched to a non-TNF biologic or a targeted synthetic DMARD (e.g., JAK inhibitor).

Cycling to another drug class provides the best chance of capturing a response when a primary mechanism-specific therapy fails.

Determine the last resort for refractory, severely symptomatic disease with structural damage.

Surgical joint replacement or arthrodesis is pursued.

When medical therapy cannot prevent joint destruction, mechanical correction is required to restore function and relieve pain.

Key Concept

Stepwise pharmacologic escalation in the management of rheumatoid arthritis.

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