Internal Medicine

3151 questions

All types3,151 Multiple choice1,611 Multiple select73 Numeric81 Matching714 Ordering672

A 54-year-old man is evaluated in the hospital on day 4 of admission for a pyogenic liver abscess. He initially presented with a 3-day history of high fever, right-sided abdominal pain, and malaise. An abdominal computed tomography scan on admission revealed a 6-cm multiloculated fluid collection in the right hepatic lobe. He underwent prompt ultrasound-guided percutaneous catheter drainage, and empiric intravenous piperacillin-tazobactam was initiated.

Today, the patient reports significant improvement and is tolerating a regular diet. His temperature is 37.0°C (98.6°F), blood pressure is 122/78 mm Hg, and pulse is 76/min. The percutaneous drain output has decreased to less than 10 mL over the past 24 hours. Blood cultures drawn at admission are sterile. Cultures from the abscess fluid have grown *Klebsiella pneumoniae*. Antimicrobial susceptibility testing indicates the organism is resistant to ampicillin, but susceptible to amoxicillin-clavulanate, ceftriaxone, and ciprofloxacin.

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

Transition to oral amoxicillin-clavulanate

Continue intravenous piperacillin-tazobactam

Transition to oral ampicillin

Add intravenous fluconazole

Discontinue all antimicrobial therapy

Show answer & explanation

Answer: Transition to oral amoxicillin-clavulanate

Answer

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

This patient has a pyogenic liver abscess that has been appropriately managed with ultrasound-guided percutaneous drainage and empiric intravenous broad-spectrum antibiotics (piperacillin-tazobactam). He is now clinically stable, afebrile, and tolerating oral intake with minimal ongoing drain output. Abscess fluid cultures have grown *Klebsiella pneumoniae* that is susceptible to several oral agents, including amoxicillin-clavulanate. In patients with pyogenic liver abscesses who have achieved adequate source control and demonstrated clinical improvement, standard practice dictates transitioning from intravenous to targeted oral antibiotics to complete a total treatment course of 4 to 6 weeks. De-escalation to oral amoxicillin-clavulanate represents proper antimicrobial stewardship by utilizing a targeted, narrow-spectrum oral agent, thereby facilitating hospital discharge and minimizing the risks associated with prolonged intravenous access.

Step-by-Step Solution

Assess the patient's clinical status and response to initial therapy.

The patient is afebrile, hemodynamically stable, tolerating a regular diet, and drain output has appropriately decreased.

Clinical stability dictates whether a patient can be safely transitioned from intravenous to oral medications.

Review the antimicrobial susceptibility testing results from the abscess fluid cultures.

The organism, Klebsiella pneumoniae, is susceptible to amoxicillin-clavulanate, ceftriaxone, and ciprofloxacin, but resistant to ampicillin.

Culture and sensitivity data are required to select a targeted, narrow-spectrum antimicrobial agent.

Determine the appropriate duration and route of ongoing antimicrobial therapy.

The patient requires a total of 4 to 6 weeks of antibiotics, which can now be safely completed with targeted oral amoxicillin-clavulanate.

Once source control is achieved and the patient is clinically stable, de-escalating from broad-spectrum IV antibiotics to a targeted oral agent is the standard of care for pyogenic liver abscesses, avoiding the risks and costs of prolonged IV therapy.

Key Concept

Management of pyogenic liver abscess involves initial source control (percutaneous drainage) and empiric intravenous antibiotics, followed by de-escalation to targeted oral antibiotics once the patient demonstrates clinical improvement and culture results are available.

Estimated Time:1m 0s

Question 3102Question →

A 62-year-old man is evaluated in the medical intensive care unit. He was admitted 8 days ago after suffering an out-of-hospital cardiac arrest and has required continuous mechanical ventilation for airway protection and management of anoxic brain injury. Three days ago, he developed a temperature of $38.8^\circ\text{C}$ ( $101.8^\circ\text{F}$ ), thick purulent secretions from the endotracheal tube, and an increased oxygen requirement. A chest radiograph obtained at that time demonstrated a new right lower lobe consolidation.

He was empirically started on broad-spectrum antimicrobial therapy with vancomycin and cefepime. Today, his clinical condition has significantly improved; he is afebrile, and his oxygenation has stabilized. A quantitative endotracheal aspirate culture obtained prior to antibiotic initiation has returned positive for heavy growth of *Staphylococcus aureus*. Susceptibility testing results are as follows:

Antimicrobial	Interpretation
Cefazolin	Susceptible
Cefepime	Susceptible
Linezolid	Susceptible
Oxacillin	Susceptible
Penicillin	Resistant
Vancomycin	Susceptible

What is the most appropriate next step in the pharmacologic management of this patient?

Add linezolid to the current antimicrobial regimen

Maintain the current regimen of vancomycin and cefepime

Discontinue vancomycin and cefepime, and initiate cefazolin

Discontinue cefepime and maintain vancomycin monotherapy

Discontinue vancomycin and maintain cefepime monotherapy

Show answer & explanation

Answer: Discontinue vancomycin and cefepime, and initiate cefazolin

Answer

Discontinue vancomycin and cefepime, and initiate cefazolin

This patient developed ventilator-associated pneumonia (VAP) and was appropriately started on empiric broad-spectrum antibiotics covering methicillin-resistant *Staphylococcus aureus* (MRSA) and *Pseudomonas aeruginosa* (vancomycin and cefepime). The endotracheal culture has now grown *S. aureus* that is susceptible to oxacillin, meaning it is methicillin-susceptible *Staphylococcus aureus* (MSSA). A core tenet of critical care and infectious disease management is antibiotic stewardship: once culture and susceptibility data are available, broad-spectrum empiric therapy must be de-escalated to targeted, narrow-spectrum therapy. For MSSA pneumonia or bacteremia, narrow-spectrum beta-lactams (such as cefazolin, oxacillin, or nafcillin) are the preferred agents. They provide more rapid bacterial clearance and better clinical outcomes compared to vancomycin. Therefore, the correct management is to discontinue both empiric broad-spectrum agents and initiate targeted therapy with cefazolin.

Step-by-Step Solution

Diagnose the specific infection based on clinical and laboratory data.

The patient developed ventilator-associated pneumonia (VAP) caused by methicillin-susceptible Staphylococcus aureus (MSSA), indicated by the positive culture and susceptibility to oxacillin.

Accurate identification of the pathogen and its resistance profile is required to tailor antimicrobial therapy.

Evaluate the current empiric therapy against the culture results.

The patient is improving on empiric vancomycin and cefepime, but these agents are overly broad given the isolated MSSA.

Empiric therapy is designed to cover a wide array of potential pathogens (e.g., MRSA, Pseudomonas) until specific culture data is available.

Apply the principles of antibiotic stewardship to modify therapy.

Therapy must be de-escalated to a narrow-spectrum agent. Intravenous cefazolin (or nafcillin/oxacillin) is selected, and empiric agents are stopped.

Beta-lactams like cefazolin are the standard of care for MSSA, demonstrating superior bacterial clearance and reduced mortality compared to vancomycin, while also minimizing selective pressure for resistant organisms.

Key Concept

In the management of ventilator-associated pneumonia, empiric broad-spectrum antibiotics should be de-escalated to a targeted, narrow-spectrum agent (e.g., cefazolin or oxacillin for MSSA) once culture and susceptibility results are available. Beta-lactams are superior to vancomycin for treating MSSA infections.

Estimated Time:1m 30s

Question 3103Question →

A 62-year-old man with a history of advanced non-small cell lung cancer is brought to the emergency department due to progressive shortness of breath and lightheadedness over the past three days. Today, he had a syncopal episode. His temperature is $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ), blood pressure is $78/48\text{ mmHg}$ , pulse is $122/\text{min}$ , and respiratory rate is $24/\text{min}$ . Pulsus paradoxus is $18\text{ mmHg}$ . Physical examination reveals distended jugular veins and distant, muffled heart sounds. Lungs are clear to auscultation bilaterally. An electrocardiogram shows sinus tachycardia with low QRS voltage and electrical alternans.

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 management sequence for this patient with acute cardiac tamponade is to first confirm the diagnosis with a bedside echocardiogram, temporize hemodynamics with an intravenous fluid bolus, definitively treat the shock with pericardiocentesis, send the fluid for diagnostic analysis, and finally consult surgery for a pericardial window to prevent recurrence.

This patient presents with Beck's triad (hypotension, distended neck veins, muffled heart sounds), pulsus paradoxus, and electrical alternans, which are classic signs of cardiac tamponade. Given his history of lung cancer, this is likely secondary to a malignant pericardial effusion. The sequential management of this life-threatening emergency must follow a strict algorithm. The immediate first step is to perform a bedside transthoracic echocardiogram to confirm the diagnosis and visualize the effusion. Once confirmed, administering a rapid intravenous normal saline bolus temporizes the patient by increasing right ventricular preload to forcibly overcome the restrictive pericardial pressure. Following this stabilization bridge, emergent ultrasound-guided pericardiocentesis must be performed to physically evacuate the fluid and restore cardiac output. After acute stabilization is achieved and the fluid is removed, the drained sample is submitted for cytological and microbiological analysis to firmly establish the malignant etiology. Finally, because malignant effusions have an exceptionally high recurrence rate, a surgical consultation for a subxiphoid pericardial window is indicated as the final step for long-term management.

Step-by-Step Solution

Confirm the diagnosis

Bedside transthoracic echocardiogram reveals a large pericardial effusion with right ventricular diastolic collapse.

Although clinical signs strongly suggest tamponade, imaging is required to confirm the diagnosis and safely guide subsequent invasive interventions.

Temporize hemodynamics

An intravenous normal saline bolus increases right-sided filling pressures.

Intravascular volume expansion helps the right ventricle overcome the elevated intrapericardial pressure, acting as a vital bridge to keep the patient alive while setting up for drainage.

Relieve pericardial pressure

Emergent ultrasound-guided pericardiocentesis drains the effusion, resolving the shock.

Evacuation of the fluid is the definitive acute, life-saving intervention for cardiac tamponade that immediately restores cardiac output.

Diagnose the underlying etiology

Pericardial fluid is sent for cytology and microbiology.

Identifying the cause (e.g., identifying malignant cells due to his history of lung cancer) is necessary to dictate long-term, disease-specific management.

Prevent future recurrence

Surgical consultation is obtained for a pericardial window.

Malignant effusions frequently and rapidly reaccumulate; a pericardial window provides a permanent drainage route into the pleural or peritoneal space.

Key Concept

The management sequence of acute cardiac tamponade relies on rapid echocardiographic confirmation, hemodynamic temporization with IV fluids, immediate pericardiocentesis, followed by diagnostic fluid analysis and definitive surgical interventions to prevent recurrence in malignant cases.

Question 3104Question →

A $55$ -year-old man with a history of type 1 diabetes mellitus and asthma is brought to the emergency department due to worsening shortness of breath, fever, and a productive cough over the past $3$ days. His temperature is $38.8^\circ\text{C}$ ( $101.8^\circ\text{F}$ ), blood pressure is $105/65$ mm Hg, pulse is $118$ /min, and respirations are $32$ /min. Pulse oximetry shows $88\%$ on room air. Physical examination reveals the use of accessory muscles of respiration, diffuse expiratory wheezes, and crackles over the right lower lung field. Laboratory studies reveal a blood glucose of $450$ mg/dL and strongly positive serum ketones. Arterial blood gas analysis on room air shows:

Variable	Value
pH	$7.22$
$PaCO_2$	$38$ mm Hg
$PaO_2$	$58$ mm Hg
$HCO_3^-$	$12$ mEq/L

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

Primary metabolic acidosis with concurrent respiratory acidosis

Primary metabolic acidosis with appropriate respiratory compensation

Primary metabolic acidosis with concurrent respiratory alkalosis

Primary respiratory acidosis with concurrent metabolic acidosis

Primary respiratory alkalosis with appropriate metabolic compensation

Show answer & explanation

Answer: Primary metabolic acidosis with concurrent respiratory acidosis

Answer

Primary metabolic acidosis with concurrent respiratory acidosis

The correct answer accurately identifies that this patient has two distinct acid-base disturbances. The primary disorder is a metabolic acidosis, driven by his diabetic ketoacidosis (evidenced by blood glucose of

450

mg/dL, positive ketones, and a low

HCO_3^-

12

mEq/L resulting in a pH of

7.22

). When a primary metabolic acidosis is present, the expected compensatory response is hyperventilation to decrease the

PaCO_2

. The adequacy of this compensation is calculated using Winter's formula: Expected

PaCO_2 = (1.5 \times [HCO_3^-]) + 8 \pm 2

. In this patient, the expected

PaCO_2 = (1.5 \times 12) + 8 = 26 \pm 2

mm Hg (range

24

28

mm Hg). The patient's actual

PaCO_2

38

mm Hg. Because the actual

PaCO_2

is greater than the expected

PaCO_2

, the patient is relatively retaining

CO_2

. This indicates a superimposed (concurrent) respiratory acidosis. Clinically, this patient with an asthma exacerbation and pneumonia is tachypneic (

32

/min) but is experiencing respiratory muscle fatigue, leading to impending respiratory failure and an inability to adequately blow off

CO_2

Step-by-Step Solution

Identify the primary acid-base disorder based on pH and

HCO_3^-

The pH is

7.22

(acidemia) and the

HCO_3^-

12

mEq/L (low), which indicates a primary metabolic acidosis.

Establishing the primary disturbance is the first step in diagnosing complex acid-base disorders.

Calculate the expected respiratory compensation using Winter's formula.

Expected

PaCO_2 = (1.5 \times [HCO_3^-]) + 8 \pm 2

. For this patient:

(1.5 \times 12) + 8 = 26 \pm 2

mm Hg. The expected range is

24

28

mm Hg.

Winter's formula determines if the respiratory response (change in

PaCO_2

) is appropriate for the degree of metabolic acidosis.

Compare the actual

PaCO_2

to the expected

PaCO_2

to identify any superimposed disorders.

The patient's actual

PaCO_2

38

mm Hg, which is significantly greater than the expected range of

24

28

mm Hg. This relative retention of

CO_2

indicates a concurrent respiratory acidosis.

PaCO_2

higher than expected in the setting of metabolic acidosis means the patient is failing to adequately hyperventilate, representing an additional, superimposed respiratory acidosis.

Key Concept

In a patient with primary metabolic acidosis, an actual PaCO2 that is higher than the expected PaCO2 calculated by Winter's formula indicates a superimposed respiratory acidosis, often serving as a sign of impending respiratory failure.

Question 3105Question →

A 58-year-old man is admitted to the hospital with a 4-day history of fever, productive cough, and right-sided pleuritic chest pain. Chest radiography reveals a right lower lobe consolidation and a large, freely flowing right-sided pleural effusion. He is initiated on empiric intravenous antibiotics. Over the course of his hospitalization, his pleural space infection proves to be highly refractory, requiring a continuous stepwise escalation of interventions. Arrange the following procedures in the standard chronological sequence utilized for the evaluation and escalating management of a progressive parapneumonic effusion, from initial assessment to definitive rescue therapy.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct chronological sequence for managing an increasingly refractory parapneumonic effusion is: diagnostic thoracentesis, followed by tube thoracostomy, then intrapleural tPA/DNase for loculations, and finally surgical decortication (VATS) if all other measures fail.

The management of parapneumonic effusions mandates a stepwise escalation based on fluid characteristics and the patient's clinical response. A diagnostic thoracentesis is the essential first step to determine if the fluid is a simple sympathetic effusion or an infected complicated effusion. Once fluid is deemed complicated (such as being frankly purulent or having a pH < 7.20), it must be drained, typically via a tube thoracostomy. If the fluid subsequently becomes heavily loculated and fails to drain adequately through the tube, the intrapleural administration of tissue plasminogen activator (tPA) and deoxyribonuclease (DNase) is used to break down fibrin septations and reduce fluid viscosity. Finally, if the infection remains uncontrolled and the lung remains trapped despite these medical and intrapleural measures, surgical decortication via video-assisted thoracoscopic surgery (VATS) is necessary as a definitive rescue therapy.

Step-by-Step Solution

Perform a diagnostic thoracentesis.

Yields pleural fluid for chemical and microbiologic analysis.

Required to definitively differentiate a simple parapneumonic effusion (managed with antibiotics alone) from a complicated one or frank empyema.

Insert a tube thoracostomy.

Achieves initial mechanical drainage of the infected pleural space.

An empyema or complicated parapneumonic effusion (fluid pH < 7.20) requires mechanical source control to clear the infection.

Administer intrapleural tPA and DNase.

Lyses fibrin adhesions and reduces pleural fluid viscosity.

Indicated when chest tube drainage is inadequate due to the formation of multiple pleural loculations.

Perform surgical decortication (VATS).

Manually removes the infected pleural peel and clears the space.

Serves as the definitive surgical rescue intervention for a persistent empyema and trapped lung despite optimized tube drainage and enzyme therapy.

Key Concept

Stepwise escalation in the management of complicated parapneumonic effusions and empyema

Estimated Time:1m 30s

Question 3106Question →

A $28$ -year-old man is brought to the emergency department by his roommate due to confusion, severe shortness of breath, and inability to lie flat. The roommate reports that the patient had a fever, myalgias, and a sore throat a week ago that had seemingly resolved. The patient's temperature is $37.1^\circ C$ ( $98.8^\circ F$ ), heart rate is $134$ /min, blood pressure is $82/55$ mm Hg, and respiratory rate is $28$ /min. Pulse oximetry shows $88\%$ on room air. On physical examination, the patient is lethargic and his extremities are cool and mottled. The jugular venous pressure is elevated at $11$ cm $H_2O$ . Lung auscultation reveals bibasilar crackles extending midway up the lung fields, along with scattered expiratory wheezes. Cardiac auscultation reveals tachycardia, a regular rhythm, and a distinct third heart sound (S3).

Laboratory results are as follows:
Leukocyte count: $8,500/mm^3$
Lactic acid: $4.5$ $mmol/L$
Troponin I: $1.2$ $ng/mL$ (normal $< 0.04$ )
Thyroid-stimulating hormone (TSH): $0.2$ $\mu U/mL$ (normal $0.4-4.0$ )
Free T4: $0.7$ $ng/dL$ (normal $0.9-1.7$ )

An electrocardiogram shows sinus tachycardia with diffuse non-specific ST-segment and T-wave abnormalities. Which of the following is the most appropriate next step in management?

Perform bedside transthoracic echocardiography

Administer intravenous furosemide and inhaled albuterol

Transport to radiology for computed tomography angiography of the chest

Administer intravenous ceftriaxone and azithromycin

Initiate oral levothyroxine therapy

Show answer & explanation

Answer: Perform bedside transthoracic echocardiography

Answer

Perform bedside transthoracic echocardiography

The correct answer is to perform bedside transthoracic echocardiography. This patient is presenting with acute cardiogenic shock, evidenced by severe hypotension (

82/55

mm Hg), poor tissue perfusion (lethargy, cool and mottled extremities, elevated lactic acid), and biventricular failure (elevated JVP, bibasilar crackles, S3 gallop). The recent history of fever, myalgias, and sore throat followed by sudden cardiac decompensation with an elevated troponin is classic for acute viral myocarditis. In any hemodynamically unstable patient, diagnostic testing must be performed at the bedside. Transthoracic echocardiography is the modality of choice as it will rapidly confirm severely depressed left ventricular systolic function and rule out other potential causes of obstructive or cardiogenic shock (such as a large pericardial effusion leading to tamponade) before initiating definitive therapy like inotropic support (e.g., dobutamine).

Step-by-Step Solution

Analyze the patient's hemodynamic status and clinical signs.

The patient is in shock (blood pressure

82/55

mm Hg, lethargy, cool/mottled extremities, lactic acidosis

4.5

mmol/L

) with signs of heart failure (JVP

11

H_2O

, pulmonary crackles, S3 gallop).

Identifying the type of shock is critical. The combination of hypotension and elevated filling pressures (JVP, pulmonary edema) definitively points to cardiogenic shock.

Correlate the shock state with the history and laboratory findings.

A recent viral prodrome followed by acute decompensated heart failure and elevated troponin in a young, previously healthy patient suggests acute viral myocarditis.

Viral myocarditis is a classic cause of sudden-onset dilated cardiomyopathy and cardiogenic shock in young adults.

Determine the safest and most diagnostic next step for an unstable patient in cardiogenic shock.

Bedside transthoracic echocardiography is selected.

An unstable patient must not leave the resuscitation area. Bedside echocardiography rapidly assesses left ventricular ejection fraction, evaluates regional wall motion, and rules out other catastrophic causes like cardiac tamponade, guiding the safe initiation of inotropic support.

Key Concept

In patients presenting with suspected cardiogenic shock (hypotension, elevated JVP, pulmonary edema), immediate bedside transthoracic echocardiography is the diagnostic test of choice to evaluate cardiac function and structure without endangering the unstable patient through transport.

Estimated Time:1m 30s

Question 3107Question →

A $70$ -year-old man with a history of chronic obstructive pulmonary disease (COPD) and hypertension is brought to the emergency department by ambulance due to the sudden onset of severe substernal chest pressure, shortness of breath, and diaphoresis that began $45\text{ minutes}$ ago. Upon arrival, his blood pressure is $85/54\text{ mmHg}$ , heart rate is $108\text{/min}$ , and respiratory rate is $22\text{/min}$ . Pulse oximetry is $94\%$ on room air. Physical examination reveals elevated jugular venous pressure with prominent $x$ and $y$ descents. Lung auscultation is clear bilaterally with mildly prolonged expiration but no wheezes or crackles. A $12$ -lead electrocardiogram demonstrates $3\text{ mm}$ ST-segment elevations in leads II, III, and aVF, with reciprocal ST-segment depressions in leads I and aVL.

In addition to preparation for emergent percutaneous coronary intervention, what is the most appropriate initial step in the management of this patient?

Intravenous furosemide

Sublingual nitroglycerin

Intravenous normal saline bolus

Inhaled albuterol and systemic corticosteroids

Noninvasive positive pressure ventilation

Show answer & explanation

Answer: Intravenous normal saline bolus

Answer

Intravenous normal saline bolus

The correct answer is an intravenous normal saline bolus. This patient's electrocardiogram shows an acute inferior wall myocardial infarction (ST elevations in leads II, III, and aVF). The accompanying clinical triad of hypotension, elevated jugular venous pressure, and clear lung fields strongly suggests a right ventricular (RV) infarction, which complicates up to 50% of inferior myocardial infarctions. The ischemic right ventricle has significantly impaired contractility and becomes highly dependent on elevated preload to maintain forward flow through the pulmonary circulation to the left ventricle. Therefore, the most appropriate initial management for hypotension in the setting of an RV infarction is volume expansion with intravenous isotonic fluids (e.g., normal saline) to maximize the Starling mechanism and improve cardiac output.

Step-by-Step Solution

Analyze the patient's clinical presentation and electrocardiogram (ECG) findings.

The patient exhibits hypotension, elevated jugular venous pressure, clear lung fields, and ST-segment elevations in inferior leads (II, III, and aVF).

Identifying the classic clinical triad combined with inferior ECG changes is essential to diagnose an acute right ventricular (RV) myocardial infarction.

Determine the pathophysiologic state of the right ventricle in this condition.

The ischemic right ventricle loses its contractility and becomes highly dependent on elevated right-sided filling pressures (preload).

Understanding RV preload dependence is crucial for selecting the correct hemodynamic intervention and avoiding fatal medication errors.

Select the appropriate initial management for the patient's hypotension.

Intravenous fluid resuscitation (e.g., normal saline) is indicated.

Increasing preload maximizes the Starling mechanism, thereby maintaining forward blood flow through the pulmonary circulation to the left ventricle and improving systemic blood pressure.

Key Concept

Right ventricular myocardial infarction presents with the triad of hypotension, elevated jugular venous pressure, and clear lungs. It is a highly preload-dependent state that requires intravenous fluid resuscitation; preload-reducing therapies must be strictly avoided.

Estimated Time:1m 15s

Question 3108Question →

A 70-year-old woman is brought to the emergency department by ambulance due to the abrupt onset of severe shortness of breath that began 45 minutes ago while she was watching television. She has a history of severe chronic obstructive pulmonary disease (COPD), hypertension, and a myocardial infarction 3 years ago. She appears extremely anxious, diaphoretic, and is speaking in one-word sentences. Vital signs are temperature $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure $225/115\text{ mmHg}$ , pulse $118\text{/min}$ , and respirations $32\text{/min}$ . Oxygen saturation is $85\%$ on room air.

Physical examination shows prominent use of accessory muscles of respiration. Lung auscultation reveals diffuse high-pitched expiratory wheezing bilaterally and bibasilar crackles. Cardiac auscultation reveals an $S_4$ gallop. There is no jugular venous distension or peripheral edema.

Arterial blood gas on room air reveals:
- pH: $7.25$
- $\text{pCO}_2$ : $65\text{ mmHg}$
- $\text{pO}_2$ : $50\text{ mmHg}$
- $\text{HCO}_3^-$ : $28\text{ mEq/L}$

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

Noninvasive positive-pressure ventilation and intravenous nitroglycerin

Nebulized ipratropium-albuterol and intravenous methylprednisolone

Intravenous furosemide and supplemental oxygen via nasal cannula

Intravenous levofloxacin and intravenous methylprednisolone

Intravenous sodium bicarbonate and endotracheal intubation

Show answer & explanation

Answer: Noninvasive positive-pressure ventilation and intravenous nitroglycerin

Answer

Noninvasive positive-pressure ventilation and intravenous nitroglycerin

This patient is presenting with Sympathetic Crashing Acute Pulmonary Edema (SCAPE), a severe phenotype of acute decompensated heart failure. SCAPE is characterized by the abrupt onset (minutes to hours) of extreme dyspnea, flash pulmonary edema, and severe hypertension resulting from a sympathetic surge and massive afterload increase. Unlike classic heart failure exacerbations, these patients are often euvolemic (no peripheral edema or JVD) but suffer from rapid fluid redistribution from the systemic circulation into the pulmonary vasculature. The prominent wheezing ('cardiac asthma') and history of COPD can mislead clinicians into diagnosing a COPD exacerbation. However, the extreme hypertension, acute onset, and

S_4

gallop strongly point to a cardiac etiology. The most appropriate initial management is rapid afterload reduction with high-dose intravenous nitroglycerin and noninvasive positive-pressure ventilation (NIPPV). NIPPV decreases left ventricular transmural pressure (reducing afterload), decreases venous return (reducing preload), and directly treats hypoxemia and the work of breathing.

Step-by-Step Solution

Analyze the clinical presentation and temporal onset.

The patient has abrupt onset (45 minutes) of severe dyspnea, extreme hypertension (225/115 mmHg), and flash pulmonary edema without peripheral edema.

Differentiates Sympathetic Crashing Acute Pulmonary Edema (SCAPE) from a typical gradual COPD exacerbation or volume-overload heart failure.

Interpret the physical exam findings.

Wheezing with bibasilar crackles and an S4 gallop indicates 'cardiac asthma' secondary to acute elevated left ventricular end-diastolic pressure, not isolated bronchospasm.

Identifies the cardiac etiology of the respiratory distress despite the history of COPD.

Evaluate the arterial blood gas results.

pH 7.25 and pCO2 65 mmHg indicate acute respiratory acidosis with severe hypoxemia.

Confirms the need for immediate ventilatory support.

Determine the most appropriate initial interventions.

Select interventions that rapidly decrease afterload and support ventilation without intubation if possible.

Intravenous nitroglycerin causes rapid vasodilation (reducing afterload and preload), while NIPPV improves oxygenation and decreases work of breathing.

Key Concept

Management of Sympathetic Crashing Acute Pulmonary Edema (SCAPE)

Estimated Time:1m 30s

Question 3109Question →

A 28-year-old woman is brought to the emergency department for severe shortness of breath and wheezing that began $6$ hours ago. She has a history of asthma and uses an albuterol inhaler as needed. For the past two days, she has had a dry cough and rhinorrhea. On initial presentation, she is anxious, diaphoretic, and speaking in one-word sentences. Her temperature is $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ), blood pressure is $135/85 \text{ mm Hg}$ , pulse is $128/\text{min}$ , and respirations are $34/\text{min}$ . Pulse oximetry is $90\%$ on room air. Physical examination shows diffuse expiratory wheezing, prolonged expiration, and prominent use of accessory muscles of respiration.

Initial arterial blood gas (ABG) on room air shows:
pH: $7.48$
$\text{PaCO}_2$ : $26 \text{ mm Hg}$
$\text{PaO}_2$ : $62 \text{ mm Hg}$

She is immediately started on high-flow oxygen, continuous nebulized albuterol, nebulized ipratropium, and intravenous methylprednisolone. One hour later, the patient appears lethargic and is no longer answering questions. Her respiratory rate is now $18/\text{min}$ . A repeat ABG on supplemental oxygen shows:
pH: $7.36$
$\text{PaCO}_2$ : $42 \text{ mm Hg}$
$\text{PaO}_2$ : $68 \text{ mm Hg}$

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

Endotracheal intubation and mechanical ventilation

Continue current medical therapy and observe closely in the intensive care unit

Noninvasive positive-pressure ventilation (NPPV)

Intravenous administration of magnesium sulfate

Intravenous administration of piperacillin-tazobactam

Show answer & explanation

Answer: Endotracheal intubation and mechanical ventilation

Answer

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

The correct answer is endotracheal intubation and mechanical ventilation. During a severe asthma exacerbation, patients initially hyperventilate, leading to a respiratory alkalosis (low

\text{PaCO}_2

). As the exacerbation progresses and airway resistance remains high, the respiratory muscles begin to fatigue. This causes minute ventilation to drop, leading to a steady rise in

\text{PaCO}_2

. A

\text{PaCO}_2

that rises into the normal range (

35-45 \text{ mm Hg}

) in a patient who is still having a severe asthma attack is known as 'pseudonormalization.' When combined with clinical signs of fatigue such as lethargy, a dropping respiratory rate, or a silent chest, it is an ominous sign of impending respiratory arrest. The immediate next step is definitive airway management with endotracheal intubation and mechanical ventilation.

Step-by-Step Solution

Analyze the initial ABG and clinical presentation.

The patient initially presented with tachypnea and a primary respiratory alkalosis (pH 7.48, PaCO2 26 mm Hg), which is the expected physiological response in an acute asthma exacerbation due to hyperventilation.

Establishing the baseline acid-base status helps track the disease trajectory.

Evaluate the clinical changes after one hour of therapy.

The patient's mental status deteriorated to lethargy, and her respiratory rate decreased from 34/min to 18/min.

Altered mental status and a slowing respiratory rate in a previously distressed asthmatic patient are critical warning signs of respiratory muscle fatigue.

Analyze the repeat ABG in the context of the clinical changes.

The repeat ABG shows a 'normal' pH (7.36) and PaCO2 (42 mm Hg).

In the setting of severe asthma and lethargy, a normalizing PaCO2 represents pseudonormalization. The patient can no longer sustain the work of breathing required to blow off CO2, signaling impending respiratory failure.

Determine the most appropriate management.

Immediate airway protection and ventilatory support are required.

Endotracheal intubation and mechanical ventilation are indicated when an asthma patient develops altered mental status, silent chest, or hypercapnia (including pseudonormalization).

Key Concept

Pseudonormalization of PaCO2 in severe asthma exacerbation indicates impending respiratory failure and requires immediate endotracheal intubation.

Estimated Time:1m 15s

Question 3110Question →

A 58-year-old man suddenly collapses while walking in the hospital hallway. He is unresponsive, apneic, and has no palpable carotid pulse. The emergency response team arrives immediately with a resuscitation cart. The cardiac monitor displays coarse ventricular fibrillation. According to the Advanced Cardiovascular Life Support (ACLS) guidelines, arrange the following management steps in the correct chronological order for this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence is: 1) Initiate high-quality chest compressions, 2) Deliver the first unsynchronized shock, 3) Immediately resume chest compressions and obtain IV access, 4) Deliver a second shock and administer epinephrine, and 5) Deliver a third shock and administer amiodarone.

The Advanced Cardiovascular Life Support (ACLS) algorithm for shockable rhythms (ventricular fibrillation or pulseless ventricular tachycardia) dictates starting with high-quality CPR. As soon as the defibrillator is ready, the first unsynchronized shock is delivered. CPR is then immediately resumed for 2 minutes while intravenous or intraosseous access is obtained; no rhythm check should occur immediately after the shock. If the rhythm remains shockable at the next check, a second shock is delivered, CPR is resumed, and epinephrine (1 mg) is administered. If the rhythm is still shockable after another 2 minutes of CPR, a third shock is delivered, CPR is resumed, and an antiarrhythmic like amiodarone (300 mg) is administered.

Step-by-Step Solution

Identify cardiac arrest and begin basic life support.

Chest compressions provide temporary circulation.

Immediate CPR is critical for survival and neurological outcome by maintaining minimal organ perfusion.

Analyze the rhythm and deliver the first shock for ventricular fibrillation.

Attempts to depolarize the myocardium to allow the sinus node to reset.

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

Immediately resume CPR and establish vascular access.

Maintains perfusion without delaying compressions.

Prolonged pauses in chest compressions (such as checking for a rhythm immediately after a shock) decrease the chance of successful defibrillation and survival.

Deliver a second shock if VF persists, resume CPR, and give epinephrine.

Epinephrine provides vasopressor support during continued arrest.

Alpha-adrenergic effects of epinephrine cause peripheral vasoconstriction, increasing aortic diastolic pressure and improving coronary perfusion pressure.

Deliver a third shock if VF persists, resume CPR, and give amiodarone.

Antiarrhythmic therapy for shock-refractory VF.

Amiodarone affects sodium, potassium, and calcium channels and has been shown to improve the rates of return of spontaneous circulation (ROSC) in shock-refractory VF.

Key Concept

Advanced Cardiovascular Life Support (ACLS) Pulseless Arrest Algorithm for Shockable Rhythms

Estimated Time:1m 30s

Question 3111Question →

A 68-year-old man is brought to the emergency department due to sudden-onset severe dyspnea that awoke him from sleep. He has a history of coronary artery disease, hypertension, type 2 diabetes mellitus, and a 40-pack-year smoking history. Temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $172/96\text{ mmHg}$ , heart rate is $115/\text{min}$ , and respiratory rate is $28/\text{min}$ . Oxygen saturation is $85\%$ on room air. Physical examination reveals the use of accessory muscles of respiration. Jugular venous distention is present while sitting upright. Lung auscultation reveals bilateral expiratory wheezes and coarse crackles at the bases. Cardiac auscultation reveals a regular tachycardia with a prominent third heart sound (S3). Arterial blood gas analysis on room air shows:

pH: $7.28$
PaCO2: $58\text{ mmHg}$
PaO2: $52\text{ mmHg}$
HCO3-: $26\text{ mEq/L}$

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

Select all that apply

Intravenous furosemide

Initiation of noninvasive positive pressure ventilation

Intravenous methylprednisolone

Intravenous piperacillin-tazobactam

Intravenous sodium bicarbonate

Show answer & explanation

Answer: Intravenous furosemide; Initiation of noninvasive positive pressure ventilation

Answer

The correct interventions are intravenous furosemide and the initiation of noninvasive positive pressure ventilation (NPPV).

The correct interventions directly address the acute volume overload and hypoxemic respiratory failure caused by acute decompensated heart failure (ADHF). Intravenous furosemide provides rapid venodilation and subsequent diuresis, reducing left ventricular preload. Noninvasive positive pressure ventilation (NPPV) provides both oxygenation support and positive intrathoracic pressure, which beneficially decreases both left ventricular preload and afterload, rapidly improving respiratory mechanics.

Step-by-Step Solution

Identify the primary clinical syndrome based on the presentation.

The patient's paroxysmal nocturnal dyspnea, jugular venous distention, S3 gallop, and bilateral crackles point strongly to acute decompensated heart failure (ADHF) with cardiogenic pulmonary edema.

Recognizing ADHF early prevents misdiagnosis as a COPD exacerbation, despite the patient's smoking history and presence of wheezing ('cardiac asthma').

Interpret the arterial blood gas values.

The ABG shows an uncompensated acute respiratory acidosis (pH

7.28

, PaCO2

58\text{ mmHg}

) and severe hypoxemia.

The expected rise in HCO3- for an acute respiratory acidosis is

1\text{ mEq/L}

for every

10\text{ mmHg}

increase in PaCO2. Since PaCO2 increased by

18\text{ mmHg}

, the HCO3- appropriately rose by approximately

1.8

26\text{ mEq/L}

, confirming no concomitant metabolic acidosis.

Select the appropriate immediate therapies for severe ADHF.

Intravenous loop diuretics (furosemide) and noninvasive positive pressure ventilation (NPPV) are selected.

These interventions rapidly decrease cardiac preload and afterload while directly addressing the severe hypoxemic and hypercapnic respiratory failure.

Key Concept

The initial management of acute decompensated heart failure with pulmonary edema involves reducing preload and afterload using intravenous diuretics, vasodilators (if normotensive or hypertensive), and noninvasive positive pressure ventilation.

Question 3112Question →

A $69$ -year-old man is brought to the emergency department by his family due to rapidly worsening shortness of breath over the past $24$ hours. He has a history of hypertension, coronary artery disease, and a $45$ -pack-year smoking history. Two weeks ago, he was evaluated at an urgent care clinic for a mild productive cough; a sputum culture at that time grew *Streptococcus pneumoniae* that was highly susceptible to penicillin.

Currently, he is sitting upright and is unable to speak in full sentences. His temperature is $37.0^\circ\text{C}$ ( $98.6^\circ\text{F}$ ), blood pressure is $168/94$ mm Hg, pulse is $112$ /min, and respirations are $28$ /min. Oxygen saturation is $88\%$ on room air.

Physical examination reveals a patient in marked respiratory distress. The jugular venous pressure is elevated at $10$ cm H $_2$ O. Chest auscultation reveals diffuse wheezing and bilateral fine crackles in the lower two-thirds of both lung fields. Cardiac examination shows tachycardia and a regular rhythm, with an extra, low-frequency sound heard just after S2 at the cardiac apex. The lower extremities show $2+$ bilateral pitting edema.

Laboratory studies are as follows:
Leukocyte count: $8,200/\text{mm}^3$
Hemoglobin: $13.4$ g/dL
Serum creatinine: $1.3$ mg/dL
Thyroid-stimulating hormone (TSH): $0.9$ mU/L (Normal: $0.5$ – $5.0$ mU/L)
Free thyroxine (T4): $0.7$ ng/dL (Normal: $0.9$ – $1.7$ ng/dL)

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

Intravenous administration of torsemide

Inhaled administration of short-acting beta-agonists

Intravenous administration of methylprednisolone

Intravenous administration of broad-spectrum levofloxacin

Initiation of oral levothyroxine therapy

Show answer & explanation

Answer: Intravenous administration of torsemide

Answer

Intravenous administration of torsemide

The correct answer provides a rapid mechanism to reduce intravascular volume and left ventricular preload. This patient's clinical picture—elevated jugular venous pressure, bibasilar crackles, an S3 gallop (an extra low-frequency sound after S2), and lower extremity edema—is pathognomonic for acute decompensated heart failure (ADHF). The diffuse wheezing is a manifestation of 'cardiac asthma,' which occurs when pulmonary venous hypertension leads to peribronchial edema and subsequent bronchospasm. The immediate administration of an intravenous loop diuretic (e.g., torsemide, furosemide, or bumetanide) is the mainstay of initial therapy for ADHF to alleviate pulmonary congestion.

Step-by-Step Solution

Analyze the patient's presentation and physical examination findings.

The patient has severe dyspnea, hypoxemia, elevated jugular venous pressure, an S3 gallop, bibasilar crackles, and bilateral pitting edema.

These findings are classic for acute left and right ventricular volume overload (Acute Decompensated Heart Failure).

Differentiate the cause of wheezing in this clinical context.

The wheezing is identified as 'cardiac asthma'—bronchospasm caused by peribronchial edema from left heart failure—rather than a primary COPD exacerbation.

The presence of an S3 gallop and elevated JVP strongly points to a cardiac etiology rather than primary pulmonary disease.

Interpret the laboratory findings.

White blood cell count is normal (ruling out acute infection). TSH is normal with a mildly low T4, representing euthyroid sick syndrome.

This rules out concurrent pneumonia or primary hypothyroidism as the driver of his decompensation.

Determine the most appropriate initial management.

Rapid preload reduction is required.

Intravenous loop diuretics (such as torsemide or bumetanide) rapidly decrease circulating volume and relieve pulmonary congestion.

Key Concept

The classic presentation of acute decompensated heart failure includes volume overload signs (elevated JVP, S3 gallop, crackles, edema) and should be initially managed with intravenous loop diuretics, even when wheezing ('cardiac asthma') is present.

Alternative Method

In cases of severe acute decompensated heart failure with hypoxemia that does not respond immediately to supplemental oxygen and diuretics, non-invasive positive pressure ventilation (NIPPV) is an important adjunct to reduce work of breathing and improve oxygenation.

Estimated Time:1m 30s

Question 3113Question →

Match the following characteristic histopathologic findings on liver biopsy to their most likely associated hepatic disorder.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Florid duct lesions match with Primary biliary cholangitis; Onion-skin fibrosis matches with Primary sclerosing cholangitis; PAS-positive diastase-resistant globules match with Alpha-1 antitrypsin deficiency; Lymphoplasmacytic infiltrate with interface hepatitis matches with Autoimmune hepatitis.

Each histologic pattern is pathognomonic for a specific chronic liver disease. Primary biliary cholangitis is defined by autoimmune granulomatous destruction of small intrahepatic bile ducts. Primary sclerosing cholangitis presents with concentric, onion-skin fibrosis around medium and large bile ducts. Alpha-1 antitrypsin deficiency causes accumulation of misfolded proteins in hepatocytes, appearing as PAS-positive, diastase-resistant globules. Autoimmune hepatitis is characterized by a prominent lymphoplasmacytic infiltrate causing interface hepatitis (piecemeal necrosis).

Step-by-Step Solution

Identify the primary pathologic target of granulomatous florid duct lesions.

It targets small intrahepatic bile ducts, which is pathognomonic for Primary biliary cholangitis (PBC).

PBC is an autoimmune condition strongly associated with anti-mitochondrial antibodies (AMA) leading to intrahepatic duct destruction.

Analyze the pattern of 'onion-skin' fibrosis.

This reflects concentric scarring around bile ducts, typical of Primary sclerosing cholangitis (PSC).

PSC is heavily associated with ulcerative colitis and affects both intrahepatic and extrahepatic biliary trees.

Correlate the finding of PAS-positive, diastase-resistant globules.

These represent accumulated unsecreted proteins, seen in Alpha-1 antitrypsin deficiency.

The mutant PiZZ protein cannot be secreted properly and accumulates in the periportal hepatocytes, eventually leading to cirrhosis.

Correlate lymphoplasmacytic infiltrate and interface hepatitis.

This is the classic histologic presentation of Autoimmune hepatitis.

Autoimmune hepatitis is an inflammatory liver disease associated with anti-smooth muscle antibodies (ASMA) and characterized by robust plasma cell infiltration.

Key Concept

Histopathologic findings in chronic liver diseases

Question 3114Question →

A $42$ -year-old woman is evaluated in the intensive care unit for worsening oxygenation. Two days ago, she was admitted to the hospital with severe acute pancreatitis. Over the past $12$ hours, she developed progressive hypoxemia and respiratory distress, requiring endotracheal intubation and mechanical ventilation. Her current ventilator settings are:

Parameter	Value
Mode	Assist-control volume ventilation
Tidal volume	$380$ mL ( $6$ mL/kg of predicted body weight)
Respiratory rate	$16$ breaths/min
Fraction of inspired oxygen ( $FiO_2$ )	$0.70$
Positive end-expiratory pressure (PEEP)	$5$ cm $H_2O$

Vital signs are temperature $37.8^\circ C$ ( $100.0^\circ F$ ), blood pressure $105/65$ mm Hg, and heart rate $112$ /min. Central venous pressure is $6$ mm Hg.
Chest radiograph reveals new-onset, bilateral, diffuse alveolar opacities without cardiomegaly or pleural effusions.
Arterial blood gas analysis on current settings shows:

Measurement	Value
pH	$7.28$
$PaCO_2$	$54$ mm Hg
$PaO_2$	$52$ mm Hg
$HCO_3^-$	$24$ mEq/L

Which of the following is the most appropriate next step in the management of this patient's respiratory failure?

Increase the positive end-expiratory pressure

Increase the tidal volume to 600 mL

Administer intravenous furosemide

Initiate intravenous meropenem

Administer intravenous sodium bicarbonate

Show answer & explanation

Answer: Increase the positive end-expiratory pressure

Answer

The most appropriate next step is to increase the positive end-expiratory pressure (PEEP).

The correct answer is to increase the positive end-expiratory pressure (PEEP). This patient has developed acute respiratory distress syndrome (ARDS) as a complication of severe acute pancreatitis. ARDS is characterized by noncardiogenic pulmonary edema, alveolar collapse, and severe intrapulmonary shunting, leading to refractory hypoxemia. Management relies on lung-protective ventilation with low tidal volumes (

6

mL/kg of predicted body weight) to prevent volutrauma, which often results in permissive hypercapnia (a mild, tolerated respiratory acidosis with pH

> 7.15-7.20

). To manage her severe hypoxemia while minimizing oxygen toxicity from high

FiO_2

(ideally kept below

0.60

), the most appropriate intervention is to increase the PEEP. Higher PEEP recruits collapsed alveoli, decreases intrapulmonary shunting, and improves the

PaO_2/FiO_2

ratio.

Step-by-Step Solution

Identify the primary diagnosis based on the clinical presentation.

The patient has acute respiratory distress syndrome (ARDS) secondary to severe acute pancreatitis, evidenced by severe hypoxemia (

PaO_2/FiO_2

ratio

< 100

) and bilateral pulmonary opacities without left heart failure.

Recognizing ARDS is necessary to apply the appropriate lung-protective mechanical ventilation protocol.

Evaluate the current ventilator settings and arterial blood gas results.

The ABG shows severe life-threatening hypoxemia (

PaO_2

52

mm Hg) despite a high

FiO_2

(

0.70

), along with a mild respiratory acidosis (pH

7.28

) due to low tidal volume ventilation.

To determine the next ventilator adjustment, one must prioritize treating the life-threatening hypoxemia while maintaining lung-protective strategies (permissive hypercapnia).

Select the appropriate ventilator adjustment to improve oxygenation.

Increase the positive end-expiratory pressure (PEEP).

In ARDS, hypoxemia is primarily caused by intrapulmonary shunting from collapsed alveoli. Increasing PEEP recruits these alveoli and improves oxygenation without risking the volutrauma associated with higher tidal volumes or the oxygen toxicity associated with prolonged

FiO_2 > 0.60

Key Concept

In the management of ARDS, severe hypoxemia is addressed by increasing positive end-expiratory pressure (PEEP) to recruit collapsed alveoli, while a mild respiratory acidosis (permissive hypercapnia) is tolerated to maintain low tidal volumes and prevent ventilator-induced lung injury.

Question 3115Question →

A 57-year-old man with a history of alcohol-associated cirrhosis is brought to the emergency department by his family due to increasing confusion and lethargy over the past 24 hours. He has also complained of diffuse abdominal discomfort. His current medications include spironolactone, furosemide, and lactulose. His temperature is $38.1^\circ\text{C}$ ( $100.6^\circ\text{F}$ ), blood pressure is $105/65\text{ mm Hg}$ , and pulse is $96/\text{min}$ . Physical examination reveals scleral icterus, spider angiomas, and a distended abdomen with shifting dullness. He is oriented only to person. Asterixis is present. Diagnostic paracentesis is performed, yielding cloudy fluid. Ascitic fluid analysis shows:

Laboratory Test	Result
Total protein	$1.1\text{ g/dL}$
Leukocyte count	$600/\mu\text{L}$
Neutrophils	$80\%$

Which of the following is the most appropriate next step in the management of this patient's acute condition?

Intravenous ceftriaxone

Intravenous meropenem

Immediate exploratory laparotomy

Increase dosage of oral lactulose

Oral ciprofloxacin

Show answer & explanation

Answer: Intravenous ceftriaxone

Answer

Intravenous ceftriaxone

The correct answer is intravenous ceftriaxone. This patient's ascitic fluid analysis shows a leukocyte count of

600/\mu\text{L}

with

80\%

neutrophils. The absolute neutrophil count (ANC) is calculated by multiplying these values (

600 \times 0.80

), resulting in an ANC of

480/\mu\text{L}

. An ascitic fluid ANC

\geq 250/\mu\text{L}

is diagnostic for spontaneous bacterial peritonitis (SBP). SBP is a severe infection in patients with cirrhosis and ascites, and it frequently precipitates hepatic encephalopathy (as seen with this patient's lethargy, confusion, and asterixis). The most common pathogens are enteric Gram-negative bacteria (e.g., Escherichia coli, Klebsiella pneumoniae) and Streptococcus species. Empiric therapy must be initiated promptly, and intravenous third-generation cephalosporins (such as ceftriaxone or cefotaxime) are the first-line treatment of choice due to their excellent coverage of these organisms and good ascitic fluid penetration.

Step-by-Step Solution

Calculate the absolute neutrophil count (ANC) of the ascitic fluid.

The ANC is calculated as

600/\mu\text{L} \times 0.80 = 480/\mu\text{L}

An ANC

\geq 250/\mu\text{L}

in ascitic fluid is the diagnostic criterion for spontaneous bacterial peritonitis (SBP).

Identify the patient's primary clinical issue based on the calculated ANC.

The patient has spontaneous bacterial peritonitis (SBP) which has precipitated acute hepatic encephalopathy.

Underlying infections are the most common triggers for acute hepatic encephalopathy in cirrhotic patients.

Select the most appropriate empiric antimicrobial therapy.

Intravenous ceftriaxone (or cefotaxime).

Intravenous third-generation cephalosporins provide optimal coverage for the most common causative organisms of SBP (enteric Gram-negative rods and Streptococcus species) without unnecessarily broad spectrum.

Key Concept

Diagnosis and management of Spontaneous Bacterial Peritonitis (SBP)

Question 3116Question →

Match each specific cardiovascular pathology with its most characteristic arterial pulse or hemodynamic physical examination finding.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Chronic severe aortic regurgitation matches with rapidly rising bounding pulse; Hypertrophic obstructive cardiomyopathy matches with bifid carotid pulse; Cardiac tamponade matches with exaggerated decrease in systolic blood pressure during inspiration; Severe calcific aortic stenosis matches with diminished and delayed carotid upstroke.

Each cardiovascular pathology produces distinct hemodynamic alterations that manifest as specific physical examination findings. Aortic regurgitation causes a widened pulse pressure and bounding pulse due to rapid forward and backward flow. Hypertrophic obstructive cardiomyopathy creates a bifid pulse due to dynamic outflow obstruction. Cardiac tamponade exaggerates ventricular interdependence, leading to pulsus paradoxus. Severe aortic stenosis creates a fixed outflow obstruction, resulting in a weak and delayed pulse.

Step-by-Step Solution

Analyze the hemodynamics of chronic severe aortic regurgitation.

Identify that rapid forward flow and backward regurgitation create a rapidly rising bounding pulse with a quick collapse.

This corresponds to the classic water-hammer or Corrigan pulse.

Analyze the hemodynamics of hypertrophic obstructive cardiomyopathy.

Identify that dynamic outflow tract obstruction causes a bifid carotid pulse with a brisk initial upstroke followed by a mid-systolic dip.

This corresponds to the classic pulsus bisferiens.

Analyze the hemodynamics of cardiac tamponade.

Identify that fixed pericardial space constraints lead to an exaggerated decrease in systolic blood pressure during inspiration (> 10 mm Hg).

This corresponds to pulsus paradoxus.

Analyze the hemodynamics of severe calcific aortic stenosis.

Identify that a fixed mechanical obstruction limits and delays forward flow, resulting in a diminished amplitude and delayed peak of the carotid upstroke.

This corresponds to pulsus parvus et tardus.

Key Concept

Physical examination correlates of cardiovascular hemodynamics and structural heart disease.

Question 3117Question →

A $65$ -year-old man comes to the clinic with a $3$ -month history of progressive exertional dyspnea, lower extremity swelling, and abdominal fullness. He has a $30$ -pack-year smoking history and mild chronic obstructive pulmonary disease. Twenty years ago, he was diagnosed with Hodgkin lymphoma and treated with chemotherapy and mantle field radiation.

Vital signs show a blood pressure of $115/75$ mm Hg, pulse of $92$ /min, and respirations of $18$ /min. Pulse oximetry is $96\%$ on room air.

Physical examination reveals an elevated jugular venous pulsation at $11$ cm H $_2$ O that paradoxically increases during inspiration. Auscultation of the heart reveals a regular rhythm and a high-frequency sound just after S $_2$ . The lungs are clear to auscultation bilaterally. The abdomen is distended with shifting dullness, and there is 2+ bilateral pitting edema to the knees.

Laboratory results are as follows:
Thyroid-stimulating hormone (TSH): $2.1$ $\mu$ U/mL (Normal: $0.4$ - $4.0$ $\mu$ U/mL)
Free T $_4$ : $1.0$ ng/dL (Normal: $0.9$ - $2.4$ ng/dL)
Total T $_3$ : $60$ ng/dL (Normal: $80$ - $200$ ng/dL)

Which of the following is the most likely primary pathophysiologic mechanism responsible for this patient's current presentation?

Restricted diastolic filling of the ventricles due to a rigid pericardium

Pulmonary arterial vasoconstriction secondary to chronic alveolar hypoxia

Left ventricular systolic dysfunction resulting in elevated pulmonary capillary wedge pressure

Decreased myocardial contractility secondary to impaired pituitary hormone production

Exaggerated drop in intrathoracic pressure during inspiration leading to decreased left ventricular stroke volume

Show answer & explanation

Answer: Restricted diastolic filling of the ventricles due to a rigid pericardium

Answer

Restricted diastolic filling of the ventricles due to a rigid pericardium

This patient's clinical presentation is highly characteristic of constrictive pericarditis, a known late complication of mediastinal radiation therapy (often used for Hodgkin lymphoma). The radiation causes chronic inflammation, leading to a thickened, fibrotic, and rigid pericardial sac. This rigid pericardium restricts the diastolic filling of the ventricles, causing blood to back up into the systemic venous system, which manifests as right-sided heart failure (elevated jugular venous pressure, hepatomegaly, ascites, and peripheral edema). Classic physical examination findings include Kussmaul sign (a paradoxical increase in jugular venous pressure during inspiration, as the right ventricle cannot accommodate the increased venous return) and a pericardial knock (a high-frequency early diastolic sound caused by the sudden cessation of ventricular filling). The patient's clear lungs indicate the absence of left heart volume overload.

Step-by-Step Solution

Analyze the patient's presenting symptoms and physical examination findings.

The patient has signs of right-sided heart failure (elevated jugular venous pressure, ascites, bilateral pitting edema) without signs of left-sided heart failure (clear lungs). He also has a Kussmaul sign (inspiratory increase in jugular venous pressure) and a pericardial knock (high-frequency early diastolic sound).

Identifying the pattern of isolated right heart failure with specific physical exam signs helps narrow the differential diagnosis.

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

The patient had mantle field radiation for Hodgkin lymphoma

20

years ago. This history, combined with Kussmaul sign and a pericardial knock, strongly suggests constrictive pericarditis.

Radiation therapy is a major risk factor for the development of constrictive pericarditis, which can occur years or decades after exposure.

Evaluate the laboratory findings to rule out confounding conditions.

The thyroid panel shows a low total T

_3

but normal TSH and free T

_4

, which is diagnostic of euthyroid sick syndrome (common in chronic heart failure), ruling out a primary or secondary thyroid disorder as the cause of his symptoms.

It is important to ensure that the symptoms are not driven by a correctable metabolic abnormality.

Determine the pathophysiologic mechanism of the confirmed diagnosis.

Constrictive pericarditis is characterized by a scarred, rigid pericardium that restricts the diastolic filling of the ventricles, leading to systemic venous congestion.

This directly answers the question regarding the underlying mechanism of the patient's presentation.

Key Concept

Constrictive Pericarditis

Question 3118Question →

A 64-year-old man is brought to the emergency department complaining of sudden-onset, severe, tearing chest pain that radiates to his interscapular region. His blood pressure is 185/110 mmHg in the right arm and 145/85 mmHg in the left arm. His heart rate is 112/min. A portable chest radiograph reveals a widened mediastinum. Acute aortic dissection is highly suspected. Arrange the following steps in the most appropriate sequential order for the acute management of this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence of management is: 1) Initiate intravenous esmolol infusion, 2) Initiate intravenous sodium nitroprusside infusion, 3) Obtain contrast-enhanced CT angiography of the chest, 4) Consult cardiothoracic surgery for definitive management.

The precise sequence for managing suspected acute aortic dissection is crucial for patient survival. The immediate goal is 'anti-impulse' therapy to reduce aortic wall shear stress. This begins with intravenous beta-blockers (e.g., esmolol) to decrease heart rate and left ventricular contractility (dP/dt). Once the heart rate is controlled, if the systolic blood pressure remains >120 mmHg, an intravenous vasodilator (e.g., sodium nitroprusside) is added. After hemodynamic stabilization, definitive imaging (CT angiography or TEE) is performed to classify the dissection, followed by surgical consultation, as Type A dissections require emergency repair.

Step-by-Step Solution

Recognize the clinical presentation and prioritize stabilization.

The patient's tearing chest pain, asymmetric blood pressures, and widened mediastinum strongly suggest an acute aortic dissection. Immediate hemodynamic stabilization is required.

Acute aortic dissection is a life-threatening emergency where ongoing shear stress on the aortic wall can lead to fatal rupture or propagation.

Determine the critical first pharmacological intervention.

Intravenous beta-blockers (e.g., esmolol or labetalol) must be administered first.

Beta-blockers reduce heart rate (target < 60/min) and decrease left ventricular contractility (dP/dt), which is the primary driver of aortic wall shear stress.

Determine the subsequent step for blood pressure control.

Intravenous vasodilators (e.g., sodium nitroprusside) are added only after adequate beta-blockade is achieved.

Vasodilators lower systolic blood pressure to the target of 100-120 mmHg. They must be given after beta-blockers to prevent reflex tachycardia and a subsequent increase in dP/dt.

Identify the next diagnostic step.

Definitive imaging with CT angiography is performed.

Once anti-impulse therapy has stabilized the hemodynamics, imaging is required to confirm the diagnosis and determine the anatomical extent (ascending vs. descending aorta).

Determine the final management step.

Consult cardiothoracic surgery.

Surgical evaluation is necessary for definitive treatment, as ascending (Type A) dissections require emergency surgical repair, while descending (Type B) dissections are typically managed medically unless complicated.

Key Concept

In the initial management of acute aortic dissection, beta-blockers (to reduce dP/dt and heart rate) MUST be administered before vasodilators (to lower blood pressure) to prevent reflex tachycardia and worsening of the dissection.

Question 3119Question →

While conducting rounds in the intensive care unit, a physician is called to the bedside of a mechanically ventilated patient who has suddenly developed profound oxygen desaturation to $78\%$ alongside persistent high peak airway pressure alarms. The heart rate has increased to $135$ /min. The patient appears diaphoretic and is making vigorous respiratory efforts out of sync with the machine. Arrange the following clinical actions in the most appropriate sequential order of execution for troubleshooting and managing this patient's acute deterioration.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence of interventions is: 1) Disconnect from ventilator and manually ventilate, 2) Perform rapid chest auscultation, 3) Pass a suction catheter, 4) Obtain a portable chest radiograph.

In any mechanically ventilated patient who suddenly deteriorates with hypoxemia and high peak airway pressure alarms, the immediate priority is to ensure oxygen delivery and rule out equipment failure. This is achieved by disconnecting the patient from the ventilator and manually ventilating with a bag-valve-mask attached to

100\%

oxygen. This action also allows the provider to feel lung compliance. The next step is a rapid physical examination to evaluate for tube displacement (e.g., mainstem intubation) or pneumothorax. Following this, passing a suction catheter assesses for and treats tube obstruction. Finally, a portable chest radiograph is obtained to confirm clinical findings.

Step-by-Step Solution

Remove the patient from the mechanical ventilator and initiate manual bag-valve-mask ventilation.

Bypasses potential ventilator machine malfunctions and provides immediate

100\%

oxygen.

This is the most critical initial intervention because it simultaneously treats hypoxemia and helps the clinician gauge airway resistance manually.

Auscultate the lungs bilaterally and assess chest rise.

Provides immediate clinical information regarding potential pneumothorax, severe bronchospasm, or tube displacement.

Physical examination is rapid and can diagnose immediately life-threatening causes of high peak pressures such as a tension pneumothorax.

Advance a suction catheter down the endotracheal tube.

Clears potential thick secretions and confirms the tube is not kinked or bitten.

Obstruction of the endotracheal tube by mucus plugs or patient biting is a common reversible cause of high airway pressures.

Order a STAT portable chest X-ray.

Visualizes the lung parenchyma, pleural space, and the exact position of the endotracheal tube tip.

Imaging is definitive but time-consuming; it must only be performed after immediate life-saving physical interventions have stabilized the patient.

Key Concept

The DOPE mnemonic (Displacement, Obstruction, Pneumothorax, Equipment) outlines the approach to sudden respiratory distress in a mechanically ventilated patient, prioritizing disconnection from the ventilator followed by sequential clinical assessment.

Estimated Time:1m 30s

Question 3120Question →

A $68$ -year-old woman is evaluated on postoperative day $3$ following an elective open sigmoid colectomy for recurrent diverticulitis. Over the past $2$ hours, she has developed significant shortness of breath, diaphoresis, and acute confusion. Her medical history is significant for hypertension, type $2$ diabetes mellitus, chronic obstructive pulmonary disease, and major depressive disorder. Her home medications, which were restarted postoperatively, include lisinopril, metformin, tiotropium, and citalopram. Temperature is $37.9^\circ$ C ( $100.2^\circ$ F), blood pressure is $82/50$ mm Hg, pulse is $122$ /min, and respirations are $28$ /min. Pulse oximetry shows $88\%$ on room air. Physical examination reveals elevated jugular venous pressure and a new, harsh, holosystolic murmur heard best at the cardiac apex with radiation to the axilla. Lung auscultation demonstrates bilateral crackles extending up to the mid-lung fields. The abdomen is soft, mildly distended, and tender near the surgical incision, which is clean and intact. An electrocardiogram reveals sinus tachycardia with $2$ -mm ST-segment depressions in leads II, III, and aVF. Which of the following is the most appropriate next step in management?

Administer inhaled albuterol and intravenous methylprednisolone

Perform immediate bedside echocardiography

Transport the patient for a computed tomography scan of the abdomen

Obtain blood cultures and initiate intravenous broad-spectrum antibiotics

Administer intravenous haloperidol to manage acute delirium

Show answer & explanation

Answer: Perform immediate bedside echocardiography

Answer

The most appropriate next step is to perform an immediate bedside echocardiography to assess for acute mitral regurgitation secondary to a perioperative myocardial infarction.

The correct action is performing a bedside echocardiogram. This patient has classic signs of acute mitral regurgitation (new holosystolic apical murmur, sudden pulmonary edema, cardiogenic shock) occurring in the setting of inferior myocardial ischemia (ST depressions in II, III, and aVF). The posteromedial papillary muscle of the mitral valve has a fragile, single blood supply from the posterior descending artery, making it highly vulnerable to ischemic dysfunction or rupture. Bedside echocardiography rapidly visualizes the valve structures and confirms the diagnosis without requiring the transport of a hemodynamically unstable patient.

Step-by-Step Solution

Identify the primary physiologic derangement.

The patient is experiencing cardiogenic shock (hypotension, tachycardia, altered mental status) accompanied by acute pulmonary edema (hypoxia, bilateral crackles).

Recognizing the shock phenotype narrows the differential diagnosis away from simple postoperative respiratory issues.

Correlate the physical examination with the electrocardiogram findings.

A new holosystolic apical murmur radiating to the axilla indicates acute mitral regurgitation. The ECG shows ischemic changes in the inferior leads (II, III, aVF).

The posteromedial papillary muscle is supplied solely by the posterior descending artery (PDA). Inferior wall ischemia frequently leads to dysfunction or rupture of this muscle, causing severe, acute mitral regurgitation.

Select the safest, most rapid diagnostic modality.

Bedside echocardiography is selected.

In a hemodynamically unstable patient, bedside ultrasound confirms the mechanical complication quickly without the risks associated with patient transport.

Key Concept

Acute mechanical complications of perioperative myocardial infarction, specifically papillary muscle dysfunction leading to acute mitral regurgitation and cardiogenic shock.

Estimated Time:1m 15s

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