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Internal Medicine

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Question 2661Question →

The intensive care team is evaluating a 64-year-old male who was intubated overnight for progressive hypoxemic and hypercapnic respiratory failure. The patient was admitted to the hospital 48 hours ago for community-acquired pneumonia. His medical history is significant for severe chronic obstructive pulmonary disease (COPD) and hypertension. He is currently sedated and receiving mechanical ventilation.

Current medications include intravenous vancomycin, cefepime, azithromycin, and continuous infusions of propofol and fentanyl.

Current ventilator settings (Volume Assist-Control):

SettingValue
Tidal volume450 mL (6 mL/kg predicted body weight)
Respiratory rate14/min
FiO2_20.50
PEEP5 cm H2_2O

Arterial blood gas (on current settings):

ParameterValue
pH7.15
PaCO2_258 mm Hg
PaO2_282 mm Hg
HCO3−_3^-20 mEq/L

Serum chemistry shows a lactate level of 4.2 mmol/L. Sputum cultures collected at the time of admission are now growing moderate *Streptococcus pneumoniae* that is susceptible to ceftriaxone, levofloxacin, and penicillin.

Physical examination reveals coarse breath sounds bilaterally with a prolonged expiratory phase. Cardiovascular examination reveals regular rate and rhythm with no murmurs. Jugular venous pressure is estimated at 6 cm H 2_2 O (normal < 8 cm H 2_2 O). There is no lower extremity edema.

Which of the following are the most appropriate next steps in the management of this patient? (Select all that apply)

Select all that apply

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Answer: Increase the mechanical ventilator's set minute ventilation; Discontinue vancomycin and cefepime, and initiate targeted therapy with intravenous ceftriaxone

Answer

The most appropriate steps are to increase the mechanical ventilator's set minute ventilation and to discontinue vancomycin and cefepime, initiating targeted therapy with intravenous ceftriaxone.
This patient is experiencing a mixed acid-base disorder alongside severe sepsis. The arterial blood gas shows marked acidemia (pH 7.15) with both a metabolic acidosis (HCO 3−_3^- of 20 mEq/L, elevated lactate) and a respiratory acidosis (PaCO 2_2 of 58 mm Hg). Using Winter's formula to calculate the expected respiratory compensation for the primary metabolic acidosis: Expected PaCO 2_2 = 1.5×20+8±2=38±21.5 \times 20 + 8 \pm 2 = 38 \pm 2 mm Hg. Because the actual PaCO 2_2 (58 mm Hg) is significantly higher than the expected range, the patient has a concurrent primary respiratory acidosis. To correct this life-threatening acidemia, the mechanical ventilator's minute ventilation must be increased (e.g., by increasing the respiratory rate). Additionally, the patient's sputum culture shows *Streptococcus pneumoniae* sensitive to ceftriaxone. Principles of antimicrobial stewardship mandate de-escalating from empiric broad-spectrum therapy (vancomycin and cefepime) to a targeted, narrow-spectrum agent (ceftriaxone) once definitive culture and susceptibility data are available.

Step-by-Step Solution

1
Analyze the arterial blood gas using Winter's formula.
Expected PaCO 2_2 = 1.5×20+8=381.5 \times 20 + 8 = 38 mm Hg. Actual PaCO 2_2 is 58 mm Hg.
To determine if the respiratory acidosis is primary or simply a failed compensatory mechanism for the underlying metabolic acidosis.
2
Adjust the mechanical ventilator settings.
Minute ventilation must be increased.
The presence of a concurrent primary respiratory acidosis (PaCO 2_2 > expected) causing severe acidemia (pH 7.15) requires increased alveolar ventilation to clear carbon dioxide.
3
Evaluate the microbiology results and current antimicrobial regimen.
Sputum grows *Streptococcus pneumoniae* susceptible to ceftriaxone, but the patient is receiving empiric vancomycin and cefepime.
To ensure targeted, pathogen-directed antibiotic therapy.
4
De-escalate the antibiotic therapy.
Discontinue vancomycin and cefepime, and start ceftriaxone.
To comply with antimicrobial stewardship protocols and reduce the risk of selecting for resistant organisms.

Key Concept

Patients with mixed metabolic and respiratory acidosis on mechanical ventilation require increased minute ventilation to correct hypercapnia. Furthermore, empiric broad-spectrum antibiotics should be strictly de-escalated once culture susceptibilities confirm a specific, sensitive organism.
Question 2662Question →

A 69-year-old man presents to the emergency department complaining of progressively worsening shortness of breath over the past 2 days. His medical history is significant for chronic obstructive pulmonary disease, essential hypertension, and a myocardial infarction 5 years ago. The patient reports a cough productive of clear sputum and states he has been sleeping in his recliner chair because lying flat makes him feel as though he is suffocating. His temperature is 37.0 C (98.6 F), blood pressure is 168/96 mmHg, pulse is 108/min, and respiratory rate is 24/min. Oxygen saturation is 90% on room air. On physical examination, the patient is in moderate respiratory distress and is using accessory muscles of respiration. Lung auscultation demonstrates bilateral end-expiratory wheezes and prominent crackles in the lower two-thirds of both lung fields. Cardiac auscultation reveals a regular tachycardia with a distinct third heart sound (S3). The jugular venous pressure is 12 cm H2O. Which of the following findings is most likely to be present on this patient's chest radiograph?

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Answer: Prominence of the upper lobe pulmonary vessels

Answer

Prominence of the upper lobe pulmonary vessels
This patient's clinical presentation of progressive dyspnea, orthopnea (manifested by sleeping in a recliner), crackles, elevated jugular venous pressure, and a third heart sound (S3) strongly suggests acute decompensated heart failure (ADHF). Although he has a history of chronic obstructive pulmonary disease (COPD) and presents with wheezing ('cardiac asthma'), the presence of an S3 gallop is highly specific for left ventricular systolic dysfunction and volume overload. The chest radiograph in ADHF classically reveals signs of pulmonary venous hypertension. The earliest radiographic sign is the redistribution of pulmonary blood flow to the upper lobes (cephalization), which appears as prominence of the upper lobe pulmonary vessels.

Step-by-Step Solution

1
Analyze the patient's presenting symptoms and medical history.
The patient has progressive dyspnea, severe orthopnea, and a history of both a myocardial infarction and COPD.
Identifying the baseline risk factors helps frame the differential diagnosis for acute respiratory distress, which here primarily includes acute decompensated heart failure and COPD exacerbation.
2
Evaluate the physical examination findings to differentiate the cause of the acute dyspnea.
Findings include an S3 gallop, elevated jugular venous pressure, bibasilar crackles, and wheezing.
While wheezing can occur in both conditions ('cardiac asthma' in heart failure), an S3 gallop and severe orthopnea are highly specific for left ventricular fluid overload, confirming acute decompensated heart failure.
3
Correlate the clinical diagnosis with expected radiographic findings.
The diagnosis is acute decompensated heart failure, which classically shows signs of pulmonary venous hypertension on imaging.
Cephalization (prominence of upper lobe vessels) is an early and characteristic chest x-ray finding in pulmonary venous congestion.

Key Concept

Patients with acute decompensated heart failure can present with wheezing (often termed 'cardiac asthma'), but specific findings like a third heart sound (S3) and orthopnea help distinguish it from a COPD exacerbation. The expected initial radiographic finding is pulmonary venous congestion, typically presenting as cephalization.
Question 2663Question →

A 62-year-old man is brought to the emergency department after falling from a 10-foot ladder while cleaning his gutters. He states he was lying on the ground for approximately 12 hours before a neighbor found him. He complains of severe, sharp pain in his right lower chest that significantly worsens when he takes a deep breath. His temperature is 36.8°C (98.2°F), blood pressure is 115/75 mmHg, pulse is 112/min, and respiratory rate is 16/min with shallow breaths. Physical examination reveals bruising and marked point tenderness over the right 7th and 8th ribs. Decreased breath sounds are noted at the right lung base.

Laboratory results are as follows:

Serum ChemistryValue
Sodium140140 mEq/L
Potassium5.25.2 mEq/L
Chloride104104 mEq/L
Bicarbonate1212 mEq/L
Blood urea nitrogen5555 mg/dL
Creatinine3.13.1 mg/dL
Creatine kinase18,50018,500 U/L
Arterial Blood Gas (Room Air)Value
pH7.167.16
PaCO2P_aCO_23535 mmHg
PaO2P_aO_26868 mmHg

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

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Answer: High anion gap metabolic acidosis and concurrent respiratory acidosis

Answer

High anion gap metabolic acidosis and concurrent respiratory acidosis
This patient has a mixed acid-base disorder: a high anion gap metabolic acidosis (HAGMA) and a concurrent respiratory acidosis. The primary disturbance is a metabolic acidosis, evidenced by severe acidemia (pH 7.167.16) and low bicarbonate (1212 mEq/L). The anion gap is elevated at 2424 mEq/L (140−[104+12]140 - [104 + 12]), confirming a HAGMA. Clinically, this is likely secondary to acute kidney injury from rhabdomyolysis (markedly elevated CK and creatinine) following his prolonged immobilization. To assess respiratory compensation, Winter's formula must be applied: ExpectedPaCO2=1.5×HCO3−+8±2Expected P_aCO_2 = 1.5 \times HCO_3^- + 8 \pm 2. For this patient, the expected PaCO2=1.5×12+8=26±2P_aCO_2 = 1.5 \times 12 + 8 = 26 \pm 2 mmHg (range: 24−2824-28 mmHg). The patient's actual PaCO2P_aCO_2 is 3535 mmHg. Because the actual PaCO2P_aCO_2 is significantly higher than the expected range, he has inadequate respiratory compensation, defining a concurrent respiratory acidosis. This hypoventilation is clinically consistent with splinting due to severe pain from his rib fractures.

Step-by-Step Solution

1
Determine the primary acid-base disturbance.
The pH is 7.167.16 (acidemia) and HCO3−HCO_3^- is 1212 mEq/L (low), indicating a primary metabolic acidosis.
The direction of the pH change matches the direction of the HCO3−HCO_3^- change, defining a metabolic primary process.
2
Calculate the anion gap (AG) to classify the metabolic acidosis.
AG=Na+−(Cl−+HCO3−)=140−(104+12)=24AG = Na^+ - (Cl^- + HCO_3^-) = 140 - (104 + 12) = 24 mEq/L.
A normal AG is 10−1410-14 mEq/L. An AG of 2424 indicates a high anion gap metabolic acidosis (HAGMA), likely due to uremia secondary to rhabdomyolysis-induced acute kidney injury.
3
Apply Winter's formula to determine the expected respiratory compensation.
ExpectedPaCO2=1.5×(HCO3−)+8±2Expected P_aCO_2 = 1.5 \times (HCO_3^-) + 8 \pm 2. Thus, 1.5×(12)+8=26±21.5 \times (12) + 8 = 26 \pm 2 mmHg (range: 2424 to 2828 mmHg).
Winter's formula predicts the appropriate compensatory hyperventilation (decrease in PaCO2P_aCO_2) for a given severity of metabolic acidosis.
4
Compare the actual PaCO2P_aCO_2 to the expected PaCO2P_aCO_2.
The actual PaCO2P_aCO_2 is 3535 mmHg, which is significantly higher than the expected range of 24−2824-28 mmHg.
When actual PaCO2P_aCO_2 is higher than expected, it indicates inadequate ventilation and a concurrent respiratory acidosis (due to pain splinting from rib fractures in this patient).
5
Check the delta-delta ratio for any occult metabolic alkalosis.
ΔAG=24−12=12\Delta AG = 24 - 12 = 12. ΔHCO3−=24−12=12\Delta HCO_3^- = 24 - 12 = 12. Ratio = 12/12=1.012 / 12 = 1.0.
A ratio between 11 and 22 implies a pure HAGMA without an additional metabolic component.

Key Concept

Patients with a primary metabolic acidosis should hyperventilate to decrease PaCO2P_aCO_2. If the actual PaCO2P_aCO_2 is higher than the expected PaCO2P_aCO_2 calculated by Winter's formula (1.5×HCO3−+8±21.5 \times HCO_3^- + 8 \pm 2), a concurrent respiratory acidosis is present.
Estimated Time:2m 0s
Question 2664Question →

A 58-year-old man presents to the emergency department with sudden-onset, severe "tearing" chest pain that radiates to his back. His blood pressure is 210/115 mm Hg in his right arm and 175/90 mm Hg in his left arm. His heart rate is 112/min. Physical examination reveals a diastolic decrescendo murmur at the right sternal border. An electrocardiogram shows sinus tachycardia, and a portable chest x-ray reveals a widened mediastinum. The physician suspects an acute aortic dissection.

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

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Answer

The correct sequence is: Administer intravenous esmolol, followed by intravenous sodium nitroprusside, then perform CT angiography of the chest, and finally transfer for emergent surgical repair.
The immediate goal in acute aortic dissection is 'anti-impulse' therapy. This involves decreasing the rate of rise of ventricular force (dP/dt) to minimize shear stress on the aortic intimal tear. Intravenous beta-blockers (e.g., esmolol, labetalol) achieve this by reducing both heart rate and contractility, making them the strict first step in medical management. Once the heart rate is controlled (< 60/min), if the systolic blood pressure remains > 120 mm Hg, an intravenous vasodilator (e.g., sodium nitroprusside) is added. Vasodilators should never be given prior to adequate beta-blockade because they trigger reflex sympathetic activation, causing tachycardia and increased contractility that propagate the dissection. Following hemodynamic stabilization, definitive imaging such as CT angiography is performed to confirm the diagnosis and anatomy. Finally, because the patient has clinical signs of ascending aortic involvement (Type A dissection) such as right-to-left arm blood pressure discrepancy and an aortic regurgitation murmur, emergent surgical repair is indicated as the definitive treatment.

Step-by-Step Solution

1
Administer intravenous esmolol
Heart rate and aortic wall shear stress (dP/dt) are decreased.
Beta-blockade is the critical first step to prevent reflex tachycardia and limit dissection propagation.
2
Administer intravenous sodium nitroprusside
Blood pressure is rapidly lowered to a target systolic of 100-120 mm Hg.
Vasodilators reduce systemic vascular resistance and blood pressure but must be given only after beta-blockade to prevent reflex sympathetic activation.
3
Perform computed tomography (CT) angiography of the chest
The presence, location, and extent of the aortic dissection are confirmed.
Definitive imaging is required to classify the dissection (Type A vs. Type B) and guide definitive therapy, but patients must be hemodynamically stabilized first if possible.
4
Transfer for emergent surgical repair
The torn aortic segment is resected and replaced with a synthetic graft.
Type A dissections (involving the ascending aorta, as suggested by the aortic regurgitation murmur) have a high risk of rupture and require emergent surgical intervention.

Key Concept

In acute aortic dissection, medical therapy must be initiated with beta-blockers before vasodilators to prevent reflex tachycardia and worsening shear stress, followed by imaging and targeted surgical or medical management.
Question 2665Question →

A 68-year-old man with a history of metastatic prostate cancer is brought to the emergency department due to progressively worsening mid-thoracic back pain, bilateral lower extremity weakness, and new-onset urinary incontinence over the past 48 hours. Neurologic examination reveals 3/53/5 motor strength in the lower extremities, hyperreflexia at the knees, and decreased pinprick sensation below the T10 dermatome. Arrange the following management steps in the most appropriate chronological sequence for evaluating and treating this patient's oncologic emergency.

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Answer

The correct sequence is to first administer high-dose intravenous dexamethasone, followed by obtaining an urgent whole-spine MRI, then consulting radiation oncology or spine surgery, and finally initiating localized definitive therapy while tapering corticosteroids.
The correct management of suspected malignant epidural spinal cord compression (MESCC) requires immediate administration of high-dose intravenous corticosteroids (e.g., dexamethasone) as the very first step. This reduces peritumoral edema and relieves pressure on the spinal cord, acting as a neuroprotective bridge. Only after steroids are given should the patient undergo an urgent whole-spine MRI, which is the gold standard for definitive diagnosis and mapping of the compression. Once the imaging confirms the lesion's anatomy, urgent consultation with radiation oncology or spine surgery is warranted for definitive treatment. Finally, after definitive therapy is enacted, the corticosteroids must be tapered to prevent adverse effects.

Step-by-Step Solution

1
Recognize the clinical presentation of malignant epidural spinal cord compression (MESCC).
The patient's triad of worsening back pain, bilateral lower extremity weakness, and autonomic dysfunction strongly suggests MESCC.
Early recognition is critical because a patient's functional outcome heavily depends on their neurologic status at the exact time treatment is initiated.
2
Administer empiric high-dose corticosteroids immediately.
Vasogenic edema surrounding the spinal cord is rapidly reduced.
Corticosteroids must be given upon clinical suspicion to protect the spinal cord from irreversible ischemic and compressive damage while awaiting confirmatory tests.
3
Perform confirmatory imaging using whole-spine MRI.
The exact anatomic level and extent of the spinal cord compression are visualized.
Whole-spine MRI is the gold standard diagnostic test and is necessary to accurately guide subsequent surgical or radiotherapeutic targets.
4
Coordinate definitive mechanical decompression and subsequent medical management.
The mechanical compression is treated by specialists, and the patient is placed on a steroid tapering schedule.
Definitive decompression prevents further tumor expansion, while tapering the initial high-dose steroids prevents long-term iatrogenic toxicity.

Key Concept

In patients with suspected malignant epidural spinal cord compression (MESCC), immediate administration of high-dose corticosteroids is the paramount first step, preceding even confirmatory MRI, to preserve neurologic function.
Question 2666Question →

A 7474-year-old woman is brought to the emergency department from a skilled nursing facility due to progressive confusion, shortness of breath, and decreased urine output over the last 4848 hours. She has a history of ischemic cardiomyopathy with a left ventricular ejection fraction of 30%30\%, severe chronic obstructive pulmonary disease (COPD), and stage III chronic kidney disease. Her temperature is 36.8∘C36.8^\circ C (98.2∘F98.2^\circ F), blood pressure is 82/5482/54 mm Hg, pulse is 118118/min, and respirations are 2828/min. Pulse oximetry shows 85%85\% on room air. Physical examination reveals a lethargic patient in moderate respiratory distress. The jugular venous pressure is estimated at 1414 cm H2OH_2O. Chest auscultation reveals bilateral basilar crackles and diffuse expiratory wheezes with a prolonged expiratory phase. Cardiac auscultation reveals a regular tachycardia and a prominent third heart sound (S3). The extremities are cool and mottled, with 2+ bilateral pitting edema extending to the knees. Laboratory studies show a leukocyte count of 11,20011,200/mm 3^3, a blood urea nitrogen of 4848 mg/dL, and a serum creatinine of 2.32.3 mg/dL (baseline 1.41.4 mg/dL). An arterial blood gas on room air reveals a pH of 7.227.22, PaCO2PaCO_2 of 6060 mm Hg, PaO2PaO_2 of 5050 mm Hg, and HCO3−HCO_3^- of 2424 mEq/L. Which of the following is the most appropriate initial management for this patient?

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Answer: Intravenous dobutamine and noninvasive positive pressure ventilation

Answer

The correct answer is to initiate intravenous dobutamine and noninvasive positive pressure ventilation.
This patient is presenting with cardiogenic shock, evidenced by severe hypotension, signs of end-organ hypoperfusion (lethargy, cool and mottled extremities, acute kidney injury), and acute decompensated heart failure (elevated jugular venous pressure, S3 gallop, pulmonary edema). The profound expiratory wheezing represents 'cardiac asthma' due to peribronchial edema rather than a primary COPD exacerbation. The most appropriate initial management is to support cardiac output and perfusion with an inotrope (such as dobutamine) and provide respiratory support with noninvasive positive pressure ventilation (NIPPV). NIPPV is especially beneficial in left ventricular failure because the positive intrathoracic pressure decreases both venous return (preload) and left ventricular transmural pressure (afterload), while concurrently improving oxygenation and reducing the work of breathing.

Step-by-Step Solution

1
Analyze the patient's hemodynamic status based on vital signs and physical examination.
The patient has marked hypotension (82/5482/54 mm Hg), cool and mottled extremities, altered mental status (lethargy), and acute kidney injury.
These findings definitively indicate a state of shock (inadequate tissue perfusion), which dictates the urgency and direction of initial management.
2
Determine the specific etiology of the shock.
The presence of an elevated jugular venous pressure (1414 cm H2OH_2O), an S3 gallop, and pulmonary edema (crackles) points specifically to cardiogenic shock rather than hypovolemic or distributive shock.
Accurately categorizing the shock prevents lethal errors, such as administering fluid resuscitation to a volume-overloaded patient.
3
Interpret the respiratory presentation and arterial blood gas values.
The wheezing represents 'cardiac asthma' secondary to peribronchial edema. The ABG shows a mixed respiratory acidosis (high PaCO2PaCO_2) and metabolic acidosis (inappropriately normal HCO3−HCO_3^- for the level of hypercapnia, likely lactic acidosis from shock).
This confirms that the respiratory failure is a consequence of acute decompensated heart failure, distinguishing it from a primary COPD exacerbation.
4
Select the most appropriate stabilizing therapies.
Inotropic support (e.g., dobutamine) is chosen to improve cardiac output and end-organ perfusion. Noninvasive positive pressure ventilation (NIPPV) is chosen to provide respiratory support.
Dobutamine directly addresses the pump failure. NIPPV is highly beneficial in cardiogenic pulmonary edema as it decreases both venous return (preload) and left ventricular transmural pressure (afterload).

Key Concept

Cardiogenic shock presenting with 'cardiac asthma' must be carefully differentiated from COPD exacerbations. Management centers on inotropic support to restore tissue perfusion and noninvasive positive pressure ventilation to reduce preload and afterload.
Estimated Time:2m 0s
Question 2667Question →

A 68-year-old man is evaluated in the emergency department for a 3-day history of progressively worsening shortness of breath, increased cough, and a change in sputum color from clear to yellow. He has a history of severe chronic obstructive pulmonary disease and primary hypothyroidism. His current medications include an albuterol inhaler as needed and daily levothyroxine. Temperature is 37.7°C (99.9°F), pulse is 105/min, respirations are 24/min, and blood pressure is 140/90 mm Hg. Pulse oximetry shows 89% on room air. Examination shows a prolonged expiratory phase with diffuse expiratory wheezing. Jugular venous pressure is normal, and there is no lower extremity edema. Laboratory studies show a leukocyte count of 9,000/mm³ and a thyroid-stimulating hormone level of 2.5 µU/mL (normal: 0.4–4.0 µU/mL). Arterial blood gas analysis on room air shows a pH of 7.36, PaCO₂ of 52 mm Hg, and HCO₃⁻ of 29 mEq/L. A chest radiograph reveals hyperinflation without focal consolidation or pulmonary vascular congestion. In addition to supplemental oxygen and inhaled short-acting bronchodilators, which of the following is the most appropriate next step in management?

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Answer: Administration of systemic glucocorticoids and an oral macrolide

Answer

Administration of systemic glucocorticoids and an oral macrolide
The correct answer is the administration of systemic glucocorticoids and an oral macrolide. This patient is experiencing an acute exacerbation of chronic obstructive pulmonary disease, defined by an acute worsening of respiratory symptoms that necessitates a change in medication. He exhibits all three cardinal symptoms: worsening dyspnea, increased cough, and increased sputum purulence (indicated by the change to a yellow color). The standard of care for an acute exacerbation includes supplemental oxygen (target saturation 88-92%), inhaled short-acting bronchodilators, systemic glucocorticoids (which shorten recovery time and improve lung function), and antibiotics. Antibiotics are specifically indicated in patients who have increased sputum purulence along with one other cardinal symptom, or those who require mechanical ventilation. A macrolide (e.g., azithromycin) is a highly appropriate choice for targeted coverage.

Step-by-Step Solution

1
Identify the primary clinical syndrome.
The patient is experiencing an acute exacerbation of chronic obstructive pulmonary disease.
He has a known history of chronic obstructive pulmonary disease and presents with the cardinal symptoms of an exacerbation: increased dyspnea, increased cough, and increased sputum purulence (yellow sputum).
2
Rule out alternative causes of acute respiratory distress based on the physical exam and diagnostic data.
Heart failure and pneumonia are unlikely causes for his presentation.
The absence of jugular venous distention, lower extremity edema, and pulmonary vascular congestion on the chest radiograph rules out decompensated heart failure. The absence of focal consolidation on the radiograph makes pneumonia unlikely.
3
Determine the appropriate pharmacologic management for the exacerbation.
The correct management includes short-acting bronchodilators, systemic glucocorticoids, and targeted antibiotics.
Systemic glucocorticoids reduce recovery time and improve lung function. Antibiotics (such as a macrolide) are specifically indicated because the patient has increased sputum purulence.

Key Concept

The management of an acute exacerbation of chronic obstructive pulmonary disease includes supplemental oxygen, inhaled short-acting bronchodilators, systemic glucocorticoids, and antibiotics (when cardinal symptoms like increased sputum purulence are present).
Question 2668Question →

A 54-year-old man is brought to the emergency department by his wife due to worsening confusion and lethargy over the past 48 hours. He has a history of decompensated alcoholic cirrhosis and was recently discharged after treatment for a variceal bleed. His home medications include nadolol, spironolactone, furosemide, and lactulose. The wife reports he has been having 2 to 3 soft bowel movements daily. Temperature is 38.1°C (100.6°F), blood pressure is 105/65 mmHg, pulse is 98/min, and respirations are 18/min. Physical examination reveals scleral icterus and spider angiomas. The abdomen is distended with a positive fluid wave and shifting dullness. There is diffuse, mild abdominal tenderness to palpation without rebound or guarding. Neurologic examination demonstrates asterixis and disorientation to time and place. Laboratory studies show a leukocyte count of 11,500/mm³, a sodium level of 131 mEq/L, and a bicarbonate level of 18 mEq/L. Which of the following is the most appropriate next step in management?

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Answer: Diagnostic paracentesis

Answer

Diagnostic paracentesis
The most appropriate next step in management for a patient with cirrhosis, ascites, and signs of clinical deterioration (fever, abdominal pain, worsening encephalopathy) is a diagnostic paracentesis. Spontaneous bacterial peritonitis (SBP) is a common, life-threatening precipitant of hepatic encephalopathy. Ascitic fluid must be obtained for cell count and culture before initiating targeted empiric antibiotic therapy, typically with a third-generation cephalosporin like cefotaxime or ceftriaxone. Delaying paracentesis or initiating antibiotics blindly can severely impair the ability to isolate the causative organism.

Step-by-Step Solution

1
Identify the primary clinical problem
A patient with decompensated cirrhosis and ascites presents with fever, diffuse abdominal pain, and worsened hepatic encephalopathy.
Recognizing the classic triad of fever, abdominal pain, and encephalopathy in a cirrhotic patient is highly suspicious for spontaneous bacterial peritonitis (SBP).
2
Determine the diagnostic requirements for the suspected condition
Ascitic fluid analysis is required to confirm the diagnosis.
SBP is diagnosed by an ascitic fluid absolute neutrophil count (ANC) ≥ 250/mm³. Fluid must be obtained before initiating antibiotics to ensure accurate cultures.
3
Select the most appropriate next step in management
Diagnostic paracentesis.
This is the most urgent and necessary step to guide definitive therapy and avoid inappropriate broad-spectrum antibiotic use or unnecessary surgical interventions.

Key Concept

Patients with cirrhosis and ascites who present with fever, abdominal pain, or worsened hepatic encephalopathy should immediately undergo a diagnostic paracentesis to evaluate for spontaneous bacterial peritonitis prior to the initiation of empiric antibiotics.
Estimated Time:1m 15s
Question 2669Question →

Match each patient presentation describing a suspected tick-borne illness with the most appropriate targeted antimicrobial therapy.

Click a left item, then click its matching right item

Items

A 52-year-old man with a history of splenectomy residing in Massachusetts presents with fever, jaundice, hemolytic anemia, and a peripheral blood smear revealing intraerythrocytic tetrads.
A 26-year-old woman at 12 weeks gestation residing in Connecticut presents with an asymptomatic, 7-cm expanding erythematous patch with central clearing on her right thigh.
A 10-year-old boy from North Carolina presents with a high fever, severe headache, and a petechial rash that originated on his wrists and ankles before spreading centrally.
A 33-year-old man from New York presents with progressive fatigue, a unilateral facial nerve palsy, and an electrocardiogram demonstrating a PR interval of 340 milliseconds.

Matches

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Answer

The correct pairings appropriately match the specific tick-borne disease presentation with its guideline-directed antimicrobial therapy: babesiosis with atovaquone/azithromycin, Lyme disease in pregnancy with oral amoxicillin, RMSF in a child with oral doxycycline, and severe Lyme carditis with PR prolongation with IV ceftriaxone.
Each clinical scenario requires specific knowledge of antimicrobial guidelines for tick-borne diseases. Babesiosis requires antiprotozoal therapy (atovaquone and azithromycin). Early Lyme disease in pregnancy necessitates amoxicillin due to doxycycline contraindications. Rocky Mountain spotted fever is a medical emergency requiring doxycycline for all ages, including children. Severe Lyme carditis (PR > 300 ms) mandates parenteral therapy with intravenous ceftriaxone.

Step-by-Step Solution

1
Analyze the first presentation: a splenectomized patient from an endemic area with hemolytic anemia and intraerythrocytic tetrads.
Diagnosis is babesiosis.
Requires identifying the classic 'Maltese cross' and the associated clinical syndrome.
2
Identify the appropriate treatment for babesiosis.
Match with atovaquone and azithromycin.
This combination is standard first-line therapy for mild to moderate babesiosis.
3
Evaluate the pregnant patient with an erythema migrans rash.
Diagnosis is early localized Lyme disease in pregnancy.
Requires recognizing the pathognomonic rash and the contraindication to standard therapy.
4
Select the appropriate antibiotic for Lyme disease in pregnancy.
Match with oral amoxicillin.
Doxycycline is teratogenic; amoxicillin is safe and effective.
5
Assess the 10-year-old child with a centripetal petechial rash and high fever.
Diagnosis is Rocky Mountain spotted fever (RMSF).
The rash pattern and region strongly suggest RMSF.
6
Determine the correct treatment for RMSF in a pediatric patient.
Match with oral doxycycline.
Doxycycline is the definitive treatment for RMSF and is indicated for all ages, superseding the usual pediatric contraindication.
7
Analyze the patient with facial nerve palsy and PR interval of 340 ms.
Diagnosis is early disseminated Lyme disease with severe carditis.
PR interval > 300 ms indicates significant heart block.
8
Select the appropriate level of therapy for severe Lyme carditis.
Match with intravenous ceftriaxone.
Oral therapy is insufficient for severe cardiac involvement; parenteral therapy is required.

Key Concept

Selection of targeted antimicrobial therapy for tick-borne diseases must account for the specific pathogen, disease severity, and patient factors (e.g., age, pregnancy, splenic function).
Question 2670Question →

A 73-year-old woman is brought to the emergency department due to a 4-day history of progressively worsening shortness of breath and an increase in the volume and purulence of her sputum. Her medical history includes severe chronic obstructive pulmonary disease (COPD) and ischemic cardiomyopathy with a left ventricular ejection fraction of 35%.

Vital signs are temperature 38.1°C (100.6°F), blood pressure 146/88 mmHg, pulse 112/min, and respirations 28/min. Pulse oximetry shows 87% on room air.

Physical examination shows a patient in respiratory distress using accessory muscles. Jugular venous pressure is estimated at 7 cm H2O. Chest auscultation reveals a prolonged expiratory phase with diffuse polyphonic wheezing. There is no lower extremity edema.

Laboratory studies show:
Leukocyte count: 14,200/mm³
B-type natriuretic peptide: 85 pg/mL

Arterial blood gas (room air):
pH: 7.26
PaCO2: 68 mmHg
PaO2: 50 mmHg
HCO3-: 30 mEq/L

A sputum Gram stain reveals numerous polymorphonuclear leukocytes and gram-negative coccobacilli. She is promptly started on noninvasive positive-pressure ventilation, nebulized ipratropium-albuterol, and intravenous methylprednisolone.

Which of the following is the most appropriate additional pharmacologic intervention for this patient?

Show answer & explanation

Answer: Oral azithromycin

Answer

The most appropriate additional intervention is the administration of oral azithromycin.
The correct intervention is oral azithromycin. This patient is experiencing a severe acute exacerbation of chronic obstructive pulmonary disease (AECOPD), characterized by the three cardinal symptoms: increased dyspnea, increased sputum volume, and increased sputum purulence. In the setting of an AECOPD with increased sputum purulence, or if the patient requires mechanical ventilation (including noninvasive positive-pressure ventilation), antibiotic therapy is strongly indicated. The Gram stain showing gram-negative coccobacilli suggests Haemophilus influenzae or Moraxella catarrhalis. A macrolide like azithromycin (or an advanced generation cephalosporin or amoxicillin-clavulanate) provides excellent coverage for these typical respiratory pathogens and atypical organisms, directly addressing the inciting infection.

Step-by-Step Solution

1
Analyze the patient's clinical presentation.
The patient has the cardinal symptoms of a COPD exacerbation (worsening dyspnea, increased sputum volume, increased sputum purulence) with fever and a normal BNP.
Differentiating between a COPD exacerbation and acute decompensated heart failure is crucial in a patient with a history of both.
2
Interpret the arterial blood gas (ABG) results.
The ABG shows a pH of 7.26, PaCO2 of 68 mmHg, and HCO3- of 30 mEq/L, indicating an acute-on-chronic respiratory acidosis.
To guide ventilatory and medical management, and to rule out concurrent metabolic acidosis.
3
Identify the required interventions based on the diagnosis.
The patient requires NIPPV, systemic corticosteroids, bronchodilators, and antibiotics targeting common respiratory pathogens.
Standard of care for a severe COPD exacerbation with all three cardinal symptoms includes these four modalities.
4
Select the most appropriate antibiotic therapy.
Azithromycin is selected to cover Haemophilus influenzae (suggested by gram-negative coccobacilli on Gram stain), Moraxella catarrhalis, and atypical organisms.
It provides targeted, appropriate coverage without violating antibiotic stewardship by using unnecessarily broad agents.

Key Concept

Patients with acute exacerbations of COPD presenting with increased sputum purulence require targeted antibiotic therapy (e.g., a macrolide, fluoroquinolone, or amoxicillin-clavulanate) in addition to bronchodilators, systemic corticosteroids, and ventilatory support.
Question 2671Question →

Match each clinical and serological laboratory profile to the most appropriate hepatobiliary diagnosis.

Click a left item, then click its matching right item

Items

Significantly elevated alkaline phosphatase, positive anti-mitochondrial antibodies (AMA), and a normal magnetic resonance cholangiopancreatography (MRCP)
Elevated alkaline phosphatase, positive p-ANCA, and multifocal stricturing with dilation of both intrahepatic and extrahepatic bile ducts on MRCP
Markedly elevated AST and ALT, elevated total IgG, positive anti-smooth muscle antibodies (ASMA), and normal biliary imaging
Elevated transferrin saturation (>45%), elevated serum ferritin, and positive HFE gene C282Y mutation
Elevated AST and ALT, decreased serum ceruloplasmin, elevated 24-hour urinary copper, and presence of Kayser-Fleischer rings

Matches

Show answer & explanation

Answer

The profiles correspond to Primary Biliary Cholangitis, Primary Sclerosing Cholangitis, Autoimmune Hepatitis, Hereditary Hemochromatosis, and Wilson Disease based on their distinct serological and imaging markers.
Each clinical profile provides a definitive set of serological, imaging, or genetic markers that pathognomonically identify specific autoimmune and metabolic liver diseases. Recognizing these distinct patterns is essential for appropriate diagnosis and targeted management.

Step-by-Step Solution

1
Determine the primary pattern of liver injury.
Profiles 1 and 2 show a cholestatic pattern (elevated alkaline phosphatase), while profiles 3, 4, and 5 show a hepatocellular or mixed pattern.
Categorizing the liver enzyme derangement narrows the differential diagnosis significantly.
2
Analyze the cholestatic profiles using imaging and specific autoantibodies.
A normal MRCP with positive AMA confirms Primary Biliary Cholangitis (small duct disease). An abnormal MRCP with strictures and positive p-ANCA confirms Primary Sclerosing Cholangitis (large duct disease).
Imaging separates microscopic from macroscopic biliary destruction, while autoantibodies provide etiological confirmation.
3
Differentiate the hepatocellular profiles using specific metabolic and autoimmune markers.
Positive ASMA and high IgG indicate Autoimmune Hepatitis. Iron overload and HFE mutation indicate Hemochromatosis. Low ceruloplasmin and high urinary copper indicate Wilson Disease.
These unique biomarkers definitively identify the underlying pathophysiology of the hepatocellular damage.

Key Concept

Diagnosis of Autoimmune and Metabolic Liver Diseases
Estimated Time:2m 0s
Question 2672Question →

A 5252-year-old woman is evaluated in the clinic due to new-onset palpitations, resting tremor, and heat intolerance over the past four weeks. She also reports a 33-kg (6.66.6-lb) unintentional weight loss despite maintaining a normal appetite. Her past medical history is unremarkable, and she takes no medications. Vital signs show a temperature of 37.1∘37.1^\circ C (98.8∘98.8^\circ F), blood pressure of 135/75135/75 mmHg, and heart rate of 112112/min. Physical examination reveals warm, moist skin, a fine resting tremor in the outstretched hands, and a diffusely enlarged thyroid gland without discrete nodules. Cardiovascular examination confirms a regular tachycardia. No exophthalmos or pretibial myxedema is noted.

Initial laboratory studies show:

Laboratory testResultReference range
Thyroid-stimulating hormone (TSH)0.030.03 μ\muU/mL0.4−4.20.4-4.2 μ\muU/mL
Free thyroxine (T4)1.41.4 ng/dL0.8−2.70.8-2.7 ng/dL

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

Show answer & explanation

Answer: Measurement of serum triiodothyronine (T3) level

Answer

Measurement of serum triiodothyronine (T3) level
The correct next step is the measurement of serum triiodothyronine (T3). This patient presents with overt clinical symptoms of hyperthyroidism (tachycardia, tremor, weight loss) and a suppressed TSH, but her Free T4 is surprisingly normal. This specific laboratory pattern can indicate either subclinical hyperthyroidism or T3 toxicosis. T3 toxicosis occurs when the thyroid gland autonomously produces excessive amounts of T3 rather than T4, which often happens in early Graves' disease or toxic nodular goiter. Because she is highly symptomatic, T3 toxicosis is strongly suspected and must be biochemically confirmed by measuring the serum T3 level before establishing the etiology with imaging or initiating antithyroid medications.

Step-by-Step Solution

1
Evaluate the clinical presentation and physical exam.
The patient exhibits classic symptoms of hyperthyroidism, including palpitations, tremor, weight loss, and tachycardia.
Identifying the clinical state dictates the urgency and direction of the laboratory workup.
2
Interpret the initial thyroid function tests.
The TSH is severely suppressed (0.030.03 μ\mu U/mL), but the Free T4 is within the normal reference range.
A suppressed TSH usually correlates with an elevated T4 in overt primary hyperthyroidism. A normal Free T4 requires further investigation.
3
Determine the next necessary diagnostic test.
Measure serum T3 to evaluate for T3 toxicosis.
In early hyperthyroidism (especially early Graves' disease or autonomous nodules), the thyroid may preferentially secrete T3 over T4. Normal T4 does not rule out thyrotoxicosis.

Key Concept

In a symptomatic patient with a suppressed TSH and a normal free T4, serum T3 must be measured to differentiate T3 toxicosis from subclinical hyperthyroidism before proceeding with imaging or treatment.
Estimated Time:1m 15s
Question 2673Question →

A 5454-year-old man is evaluated in the hospital on his third day of admission for community-acquired pneumonia. He was initially started on empiric therapy with intravenous ceftriaxone and oral azithromycin. His cough and shortness of breath have significantly improved, and he has been afebrile for the past 2424 hours. He is currently tolerating a regular diet. Sputum cultures collected on admission grew *Streptococcus pneumoniae*. Susceptibility testing reveals that the isolate is susceptible to penicillin, amoxicillin, ceftriaxone, levofloxacin, and vancomycin, and resistant to azithromycin. He has no known drug allergies. Vital signs are temperature 37.0∘C37.0^\circ\text{C} (98.6∘F98.6^\circ\text{F}), pulse 76/min76/\text{min}, respirations 14/min14/\text{min}, and blood pressure 124/78 mmHg124/78\text{ mmHg}. Pulse oximetry is 97%97\% on room air. The patient is being prepared for discharge. Which of the following is the most appropriate antimicrobial regimen to prescribe for this patient upon discharge?

Show answer & explanation

Answer: Oral amoxicillin

Answer

Oral amoxicillin is the most appropriate discharge antibiotic regimen.
The most appropriate next step is to transition this patient to oral amoxicillin. He is clinically stable, afebrile, and tolerating oral intake, which meets all criteria for transitioning from intravenous to oral antibiotics. The sputum culture grew *Streptococcus pneumoniae* that is susceptible to penicillin and amoxicillin. Principles of antimicrobial stewardship dictate that once a pathogen is identified and susceptibilities are known, empiric broad-spectrum therapy should be de-escalated to the narrowest effective agent. Oral amoxicillin provides excellent targeted coverage for susceptible *S. pneumoniae* and is the preferred first-line step-down agent in this clinical scenario.

Step-by-Step Solution

1
Assess the patient's clinical stability for transition to oral therapy.
The patient is afebrile, clinically improving, and tolerating an oral diet, making him eligible for oral step-down therapy.
Transitioning to oral antibiotics reduces hospital stay and intravenous catheter complications.
2
Evaluate the sputum culture and susceptibility results.
The infection is driven by Streptococcus pneumoniae that is susceptible to penicillin and amoxicillin.
Culture data guides the de-escalation of empiric therapy.
3
Select the narrowest-spectrum effective oral antibiotic.
Oral amoxicillin is selected over broader agents.
This adheres to antimicrobial stewardship principles, preventing resistance and minimizing adverse effects.

Key Concept

Antibiotic de-escalation involves transitioning from broad-spectrum empiric therapy to the narrowest-spectrum effective oral agent once culture and susceptibility data are available and the patient is clinically stable.
Question 2674Question →

A 68-year-old man with a history of hypertension and type 2 diabetes mellitus presents to the emergency department with palpitations, fatigue, and mild shortness of breath that began 3 days ago. His blood pressure is 125/80 mm Hg, heart rate is 142/min and irregularly irregular, and respiratory rate is 18/min. An electrocardiogram confirms atrial fibrillation with rapid ventricular response. The physician decides to pursue an early rhythm control strategy to alleviate his persistent symptoms.

Arrange the following management steps in the most appropriate chronological sequence for this patient:

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Administer AV nodal blocker, 2) Initiate systemic anticoagulation, 3) Perform transesophageal echocardiogram, 4) Perform synchronized electrical cardioversion, 5) Continue long-term oral anticoagulation.
The correct sequence prioritizes immediate stabilization with rate control. Even when early rhythm control is desired, the rapid ventricular rate must be managed first. Because the arrhythmia has persisted for >48 hours, systemic anticoagulation is initiated immediately to prevent clot formation. To safely perform early cardioversion without a prior 3-week period of anticoagulation, a transesophageal echocardiogram (TEE) is then required to definitively rule out a left atrial appendage thrombus. Once confirmed clear, synchronized electrical cardioversion is safely performed. Finally, continuous long-term oral anticoagulation is maintained based on the patient's elevated CHA2DS2-VASc score.

Step-by-Step Solution

1
Administer an intravenous AV nodal blocking agent (diltiazem or metoprolol).
Decreased ventricular rate and relief of acute symptoms.
Immediate rate control is prioritized to improve diastolic filling time and prevent hemodynamic decompensation while preparing for further interventions.
2
Initiate therapeutic systemic anticoagulation.
Prevention of new thrombus formation.
Because the atrial fibrillation has been present for >48 hours, the risk of left atrial thrombus is high. Anticoagulation must be active prior to imaging and cardioversion.
3
Perform a transesophageal echocardiogram (TEE).
Visualization of the left atrial appendage.
Before restoring sinus rhythm in a patient with atrial fibrillation >48 hours without prior 3-week anticoagulation, a TEE is mandatory to rule out a pre-existing thrombus, which could embolize upon cardioversion.
4
Perform synchronized electrical cardioversion.
Restoration of normal sinus rhythm.
With a thrombus ruled out and the patient safely anticoagulated, electrical cardioversion can be performed to achieve the planned early rhythm control.
5
Continue long-term oral anticoagulation therapy.
Long-term stroke prevention.
Post-cardioversion, patients require at least 4 weeks of anticoagulation. This patient's CHA2DS2-VASc score of 2 necessitates lifelong therapy to mitigate future stroke risk.

Key Concept

In patients with stable atrial fibrillation lasting >48 hours who are planned for early rhythm control, the sequence of management must prioritize initial rate control, immediate initiation of anticoagulation, a TEE to rule out left atrial appendage thrombus, synchronized cardioversion, and subsequent long-term anticoagulation.

Alternative Method

An alternative approach to early TEE-guided cardioversion is to simply achieve strict rate control and therapeutically anticoagulate the patient for a full 3 to 4 weeks prior to cardioversion. This eliminates the need for a TEE, provided the patient can tolerate being in atrial fibrillation for that duration.
Estimated Time:1m 30s
Question 2675Question →

A medical team is reviewing arterial blood gas and basic metabolic panel results for several patients in the intensive care and step-down units. Match each patient's clinical presentation with their most likely primary acid-base disturbance.

Click a left item, then click its matching right item

Items

A 22-year-old with recurrent vomiting due to severe gastroparesis, presenting with dehydration and muscle cramps
A 28-year-old presenting with perioral numbness and carpopedal spasm during a severe panic attack
A 45-year-old with a high-output ileostomy presenting with lethargy and profound weakness
A 55-year-old with acute mesenteric ischemia presenting with an acute abdomen and hypotension
A 65-year-old with a severe exacerbation of chronic bronchitis presenting with somnolence and a depressed respiratory drive

Matches

Show answer & explanation

Answer

The correct pairings match upper GI losses to metabolic alkalosis, hyperventilation to respiratory alkalosis, lower GI losses to normal anion gap acidosis, tissue ischemia to high anion gap acidosis, and hypoventilation to respiratory acidosis.
Each clinical scenario uniquely maps to a single primary acid-base disturbance: vomiting causes H+ loss (alkalosis), hyperventilation blows off CO2 (respiratory alkalosis), an ileostomy loses HCO3- (normal AG acidosis), ischemia generates lactate (high AG acidosis), and hypoventilation retains CO2 (respiratory acidosis).

Step-by-Step Solution

1
Analyze the acid-base impact of recurrent vomiting.
Metabolic alkalosis.
Loss of gastric acid (H+) and volume depletion-induced aldosterone release lead to net bicarbonate retention and chloride loss.
2
Analyze the acid-base impact of hyperventilation.
Respiratory alkalosis.
An increased respiratory rate directly blows off CO2, lowering PaCO2 and raising pH.
3
Analyze the acid-base impact of lower gastrointestinal fluid losses (e.g., via an ileostomy).
Normal anion gap metabolic acidosis.
Direct loss of bicarbonate-rich fluid from the lower GI tract causes a non-anion gap acidosis, which is balanced by renal chloride retention.
4
Analyze the acid-base impact of acute mesenteric ischemia.
High anion gap metabolic acidosis.
Tissue ischemia rapidly produces lactate, an unmeasured anion that consumes bicarbonate and increases the anion gap.
5
Analyze the acid-base impact of a COPD exacerbation with hypoventilation.
Respiratory acidosis.
Hypoventilation and worsened ventilation-perfusion mismatch lead to acute CO2 retention in the blood.

Key Concept

Different clinical scenarios produce distinct primary acid-base disturbances based on the underlying mechanism (e.g., GI loss of acid vs. base, tissue hypoxia, ventilation changes).
Question 2676Question →

An emergency medical services team brings a 7676-year-old female resident of a skilled nursing facility to the hospital because of severe respiratory distress that awakened her from sleep. The patient is unable to speak in full sentences and is actively coughing up pink, frothy sputum. Her past medical history is notable for systemic hypertension, osteoarthritis, and a 3030-pack-year history of smoking (quit 1515 years ago). Two weeks ago, she was prescribed daily naproxen for worsening knee pain.

Upon arrival, her temperature is 36.9∘C36.9^\circ\text{C} (98.4∘F98.4^\circ\text{F}), blood pressure is 192/108 mmHg192/108\text{ mmHg}, heart rate is 118/min118/\text{min}, and respiratory rate is 30/min30/\text{min}. Oxygen saturation is 84%84\% on room air.

Physical examination displays prominent use of accessory respiratory muscles. The internal jugular vein is visibly distended while the patient is sitting upright. Chest auscultation reveals diffuse expiratory wheezes and coarse crackles extending halfway up both lung fields. Cardiac examination is significant for a rapid, regular rhythm with a distinct low-frequency sound heard just after S2S_2.

An electrocardiogram shows sinus tachycardia with left ventricular hypertrophy but no acute ischemic changes.

Which of the following is the most appropriate initial pharmacological therapy for this patient?

Show answer & explanation

Answer: Intravenous furosemide

Answer

Intravenous furosemide
Intravenous furosemide is the correct choice because the patient is presenting with acute decompensated heart failure (ADHF). This is evidenced by severe dyspnea, an S3S_3 gallop (the low-frequency sound after S2S_2), jugular venous distension, and pink frothy sputum. The recent initiation of an NSAID (naproxen) likely caused sodium and water retention, exacerbating her hypertension and precipitating the heart failure episode. Intravenous loop diuretics like furosemide rapidly decrease preload through direct venodilation and subsequent brisk diuresis, effectively relieving the acute pulmonary edema.

Step-by-Step Solution

1
Analyze the patient's symptoms, vital signs, and recent history.
The patient has acute respiratory distress, severe hypertension, hypoxia, and recently started an NSAID (naproxen).
To establish the acuity of the presentation and identify potential triggers for the decompensation.
2
Interpret the physical examination findings.
The presence of an S3S_3 gallop, jugular venous distension (JVD), bibasilar crackles, and pink, frothy sputum strongly indicates volume overload and elevated left ventricular end-diastolic pressure.
To differentiate between pulmonary (e.g., COPD, pneumonia) and cardiac causes of severe dyspnea.
3
Synthesize the findings to establish a diagnosis.
The diagnosis is acute decompensated heart failure (ADHF) causing acute pulmonary edema, likely precipitated by NSAID-induced fluid retention and exacerbation of hypertension.
NSAids inhibit prostaglandins, reducing renal blood flow and causing sodium and water retention.
4
Select the most appropriate initial pharmacological therapy.
Administer an intravenous loop diuretic (such as furosemide).
Loop diuretics rapidly reduce central venous pressure and pulmonary capillary wedge pressure through immediate venodilation and subsequent diuresis, relieving the pulmonary edema.

Key Concept

Diagnosis and acute pharmacological management of acute decompensated heart failure presenting with 'cardiac asthma'.

Alternative Method

In patients with acute decompensated heart failure and severe hypertension, intravenous vasodilators (such as nitroglycerin) are often used as an adjunct alongside loop diuretics to rapidly reduce both preload and afterload. Non-invasive positive pressure ventilation (NIPPV) is also a critical non-pharmacological adjunct to decrease work of breathing and reduce preload.
Estimated Time:1m 30s
Question 2677Question →

A 7272-year-old woman is evaluated in the hospital for sudden-onset shortness of breath and right-sided pleuritic chest pain. She was admitted 33 days ago for an elective left total hip arthroplasty. Her past medical history is significant for ischemic cardiomyopathy (baseline left ventricular ejection fraction 45%45\%), mild chronic obstructive pulmonary disease, and a pituitary macroadenoma treated with transsphenoidal resection 55 years ago resulting in panhypopituitarism. Her current medications include aspirin, lisinopril, metoprolol succinate, tiotropium, hydrocortisone, and levothyroxine.

Temperature is 37.6∘C37.6^\circ C (99.7∘F99.7^\circ F), pulse is 118/min118/min, blood pressure is 132/84132/84 mm Hg, and respirations are 26/min26/min. Pulse oximetry shows 88%88\% on room air. Physical examination reveals clear lungs to auscultation bilaterally. The jugular venous pressure is 99 cm H2OH_2O. The right calf is swollen, erythematous, and tender to palpation.

Laboratory results are as follows:
Leukocyte count: 9,500/mm39,500/mm^3
Thyroid-stimulating hormone (TSH): 1.1μU/mL1.1 \mu U/mL (Normal: 0.4−4.0μU/mL0.4-4.0 \mu U/mL)
Free thyroxine (T4): 0.6ng/dL0.6 ng/dL (Normal: 0.9−1.7ng/dL0.9-1.7 ng/dL)

Arterial blood gas on room air:
pH: 7.507.50
PaCO2PaCO_2: 2828 mm Hg
PaO2PaO_2: 5656 mm Hg
HCO3−HCO_3^-: 22mEq/L22 mEq/L

An electrocardiogram shows sinus tachycardia with a prominent S wave in lead I, a Q wave in lead III, and an inverted T wave in lead III.

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

Show answer & explanation

Answer: Computed tomography angiography of the chest

Answer

Computed tomography angiography of the chest
The correct answer is computed tomography angiography of the chest because this patient presents with classic signs of an acute pulmonary embolism (PE). Her presentation includes sudden-onset dyspnea, pleuritic chest pain, tachycardia, hypoxia, and evidence of a deep vein thrombosis (DVT) in the setting of recent major orthopedic surgery (total hip arthroplasty). Her arterial blood gas demonstrates acute respiratory alkalosis secondary to hyperventilation, and the electrocardiogram shows the S1Q3T3 pattern, which reflects acute right ventricular strain. For hemodynamically stable patients with a high clinical probability of PE, the definitive diagnostic imaging modality is CT pulmonary angiography.

Step-by-Step Solution

1
Analyze the patient's clinical presentation and risk factors.
The patient has sudden-onset dyspnea, pleuritic chest pain, hypoxia, and unilateral calf swelling 33 days after major orthopedic surgery.
This combination is highly suspicious for a deep vein thrombosis (DVT) that has embolized, causing an acute pulmonary embolism (PE).
2
Interpret the diagnostic data provided in the stem.
The ABG reveals a primary respiratory alkalosis (pH 7.507.50, low PaCO2PaCO_2) driven by tachypnea. The ECG demonstrates the classic S1Q3T3 pattern.
Respiratory alkalosis and the S1Q3T3 pattern (indicating acute right ventricular strain) further support the diagnosis of acute PE.
3
Determine the next best step in management.
Computed tomography (CT) angiography of the chest is the most appropriate next step.
In a hemodynamically stable patient with a high pretest probability for PE (elevated Wells score), CT pulmonary angiography is the definitive diagnostic imaging modality before initiating long-term anticoagulation.

Key Concept

The diagnosis of pulmonary embolism in a hemodynamically stable patient with high clinical suspicion relies on computed tomography (CT) pulmonary angiography.
Estimated Time:1m 30s
Question 2678Question →

Match the following structural heart pathologies with their characteristic auscultatory findings and their specific responses to physiological maneuvers.

Click a left item, then click its matching right item

Items

Hypertrophic cardiomyopathy
Mitral valve prolapse
Aortic stenosis
Aortic regurgitation

Matches

Show answer & explanation

Answer

Hypertrophic cardiomyopathy matches with the systolic murmur that increases with Valsalva; Mitral valve prolapse matches with the murmur and click that occur earlier upon standing; Aortic stenosis matches with the systolic murmur that decreases with Valsalva; Aortic regurgitation matches with the diastolic murmur accentuated by leaning forward.
Physiologic maneuvers alter cardiac hemodynamics, specifically preload and afterload, to aid in differentiating murmurs. Decreasing preload (via the Valsalva strain phase or abrupt standing) decreases left ventricular chamber size. This decreases the intensity of most murmurs, such as aortic stenosis, due to reduced forward flow. However, decreased preload increases the murmur of hypertrophic cardiomyopathy by worsening the dynamic left ventricular outflow tract obstruction, and causes the click and murmur of mitral valve prolapse to occur earlier in systole. Aortic regurgitation, on the other hand, is uniquely accentuated by structural positioning (leaning forward at end-expiration) rather than dynamic volume shifts.

Step-by-Step Solution

1
Analyze the effect of the Valsalva maneuver on left ventricular volume and its impact on hypertrophic cardiomyopathy versus aortic stenosis.
The strain phase of the Valsalva maneuver decreases preload. This increases the murmur of hypertrophic cardiomyopathy by worsening the dynamic obstruction, but decreases the murmur of aortic stenosis due to less blood flow across a fixed obstruction.
Differentiating between dynamic and fixed left ventricular outflow tract obstructions is critical for distinguishing these two systolic crescendo-decrescendo murmurs.
2
Analyze the effect of abruptly standing on the timing of mitral valve prolapse auscultatory findings.
Standing decreases preload, rendering the left ventricle smaller. This structural change causes the mitral valve prolapse to happen earlier in systole, creating an earlier click and a longer murmur.
Understanding how left ventricular volume mechanically affects the timing of the redundant leaflet prolapse confirms the diagnosis.
3
Identify the characteristic presentation and optimal auscultation technique for aortic regurgitation.
It is an early diastolic murmur best heard when the patient sits up, leans forward, and exhales completely.
This specific physical maneuver minimizes anatomical interference by bringing the aortic valve closer to the anterior chest wall, optimizing the auscultation of high-pitched diastolic murmurs.

Key Concept

The physiological response of cardiac murmurs to maneuvers that alter venous return (preload) or afterload is essential for differentiating underlying valvular and structural heart pathologies.
Estimated Time:1m 30s
Question 2679Question →

A 5858-year-old woman is mechanically ventilated in the intensive care unit for acute respiratory distress syndrome (ARDS) secondary to severe pneumonia. She has shown significant clinical improvement over the past 4848 hours. Arrange the following steps in the standard, evidence-based sequential order for assessing readiness and executing liberation from mechanical ventilation.

Drag items to arrange them in the correct order

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Answer

The correct sequence for liberating a patient from mechanical ventilation begins with confirming clinical stability, followed by a Spontaneous Awakening Trial (SAT), then a Spontaneous Breathing Trial (SBT), a cuff leak test to check for airway edema, and finally extubation.
The evidence-based approach to liberating a patient from mechanical ventilation follows a strict step-wise protocol to ensure safety. First, the patient must meet objective criteria indicating the underlying illness has resolved (e.g., low FiO2FiO_2 and PEEP). Second, sedation must be interrupted (SAT) to allow the patient to wake up and regain their respiratory drive. Third, once awake, their physical ability to breathe without the ventilator is tested via an SBT. Fourth, before removing the tube, a cuff leak test is performed to rule out laryngeal edema. Finally, if all steps are successfully passed, the patient is extubated.

Step-by-Step Solution

1
Assess objective readiness criteria.
Confirm stability on PEEP≤8PEEP \leq 8 cm H2OH_2O and FiO2≤0.40FiO_2 \leq 0.40.
Ensures the underlying pathology has sufficiently resolved.
2
Initiate Spontaneous Awakening Trial (SAT).
Sedation is turned off or minimized.
Patient must be awake and neurologically capable of initiating breaths.
3
Perform Spontaneous Breathing Trial (SBT).
Patient breathes with minimal support for 30−12030-120 minutes.
Tests the physiological ability to maintain gas exchange and work of breathing.
4
Check airway patency.
Perform a cuff leak test.
Identifies laryngeal edema which could cause post-extubation stridor and failure.
5
Extubate the patient.
Removal of the endotracheal tube.
Completes the liberation process once all safety checks are passed.

Key Concept

Standard protocol for liberation from mechanical ventilation (ABCDEF bundle)
Question 2680Question →

A 74-year-old man is hospitalized for symptomatic anemia secondary to newly diagnosed myelodysplastic syndrome. His medical history includes chronic obstructive pulmonary disease (COPD) and essential hypertension. His pre-transfusion hemoglobin is 6.1 g/dL.

A transfusion of two units of packed red blood cells is ordered. Thirty minutes into the transfusion of the second unit, the patient reports acute-onset shortness of breath and a dry cough. A urine culture sent on admission for mild dysuria has just resulted, showing >100,000 CFU/mL of *Escherichia coli* that is susceptible to nitrofurantoin and cephalexin, but resistant to ciprofloxacin.

Temperature is 37.1°C (98.8°F), blood pressure is 185/95 mm Hg, pulse is 112/min, and respirations are 28/min. Pulse oximetry shows an oxygen saturation of 85% on room air. Physical examination reveals prominent jugular venous distention. Cardiac examination shows regular tachycardia with a loud S3 gallop. Pulmonary examination reveals bilateral crackles extending halfway up the lung fields, with scattered expiratory wheezes.

Arterial blood gas analysis on room air shows:

ParameterValueReference Range
pH7.317.35 - 7.45
pCO2pCO_249 mm Hg35 - 45 mm Hg
pO2pO_252 mm Hg75 - 105 mm Hg
HCO3−HCO_3^-24 mEq/L22 - 28 mEq/L

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

Show answer & explanation

Answer: Discontinue the transfusion and administer intravenous furosemide

Answer

The most appropriate next step is to discontinue the transfusion and administer intravenous furosemide to manage Transfusion-Associated Circulatory Overload (TACO).
The patient's presentation of acute dyspnea, hypertension, elevated jugular venous pressure, an S3 gallop, and basilar crackles during a blood transfusion is pathognomonic for Transfusion-Associated Circulatory Overload (TACO). TACO occurs when a large volume of blood products is administered rapidly, particularly in patients with underlying cardiopulmonary disease or advanced age (such as this elderly man with COPD and hypertension). The hydrostatic pressure in the pulmonary capillaries increases, leading to acute cardiogenic pulmonary edema. The ABG demonstrates an acute respiratory acidosis secondary to impaired gas exchange. The immediate and most critical steps in management are to discontinue the transfusion, provide supplemental oxygen, and administer intravenous loop diuretics (e.g., furosemide) to reduce intravascular volume and cardiac preload.

Step-by-Step Solution

1
Analyze the patient's acute symptoms and physical examination findings.
The patient developed acute dyspnea, hypertension, tachycardia, hypoxia, elevated JVP, an S3 gallop, and pulmonary crackles during a blood transfusion.
Identifying the constellation of cardiogenic pulmonary edema signs helps differentiate TACO from TRALI (which typically presents with hypotension and no JVD).
2
Interpret the arterial blood gas results.
The ABG shows a low pH (7.31), elevated pCO2 (49 mm Hg), and normal HCO3 (24 mEq/L), indicating an acute, uncompensated respiratory acidosis.
This confirms respiratory failure due to fluid overload (pulmonary edema) rather than a primary metabolic derangement.
3
Determine the optimal immediate management strategy.
The correct action is to immediately stop the transfusion to prevent further fluid administration, provide supplemental oxygen, and administer loop diuretics (intravenous furosemide).
Diuresis rapidly decreases intravascular volume, reducing cardiac preload and relieving the hydrostatic pulmonary edema associated with TACO.

Key Concept

Transfusion-Associated Circulatory Overload (TACO) presents with signs of volume overload (hypertension, elevated JVP, S3 gallop, pulmonary edema) and is managed by stopping the transfusion and administering loop diuretics and oxygen.
Estimated Time:1m 15s
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