Internal Medicine

3151 questions

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

A woman, aged 48, is brought to the acute care clinic by her husband due to a 3-day history of worsening shortness of breath, severe headache, and blurry vision. She has known diagnoses of diffuse cutaneous systemic sclerosis and hypothyroidism, for which she takes mycophenolate mofetil and levothyroxine. Her temperature is 37.1°C (98.8°F), blood pressure is 225/115 mm Hg, heart rate is 108/min, and respiratory rate is 26/min. Oxygen saturation is 91% on ambient air. Physical examination reveals thickened, tight skin over the face, trunk, and proximal extremities. Funduscopic examination shows bilateral flame-shaped hemorrhages. Cardiopulmonary auscultation reveals bilateral basilar crackles and a loud $S_2$ . There is 2+ pitting edema of the lower extremities.

Laboratory evaluations show:
- Hemoglobin: 8.4 g/dL
- Platelets: 85,000/mm $^3$
- Leukocytes: 11,500/mm $^3$
- Serum creatinine: 3.2 mg/dL (baseline was 0.9 mg/dL two months ago)
- Blood urea nitrogen: 48 mg/dL
- TSH: 2.5 $\mu$ U/mL (Reference: 0.4-4.0 $\mu$ U/mL)
- Free T4: 0.5 ng/dL (Reference: 0.9-1.7 ng/dL)
- Peripheral blood smear: 3-5 schistocytes per high-power field
- Arterial blood gas (ambient air): pH 7.32, $pCO_2$ 30 mm Hg, $pO_2$ 65 mm Hg, $HCO_3^-$ 15 mEq/L

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

Administer inhaled albuterol and systemic glucocorticoids

Administer intravenous sodium bicarbonate for uncompensated metabolic acidosis

Initiate oral captopril therapy

Initiate intravenous vancomycin and piperacillin-tazobactam

Increase the levothyroxine dose for presumed primary hypothyroidism

Show answer & explanation

Answer: Initiate oral captopril therapy

Answer

Initiate oral captopril therapy

The patient's presentation of malignant hypertension, acute kidney injury, and microangiopathic hemolytic anemia in the setting of diffuse cutaneous systemic sclerosis is highly characteristic of scleroderma renal crisis (SRC). SRC is precipitated by renal vascular injury leading to severe ischemia and a massive surge in renin production. The first-line, life-saving treatment is the rapid initiation of an angiotensin-converting enzyme (ACE) inhibitor, typically captopril, to directly counteract the renin-angiotensin-aldosterone system (RAAS) hyperactivation. Even in the presence of acute kidney injury, ACE inhibitors must be started and titrated to control blood pressure.

Step-by-Step Solution

Identify the primary clinical syndrome based on the patient's history and presentation.

The patient has systemic sclerosis and presents with new-onset malignant hypertension, acute kidney injury, and microangiopathic hemolytic anemia (schistocytes, thrombocytopenia).

This triad of findings in a patient with diffuse cutaneous systemic sclerosis establishes the diagnosis of scleroderma renal crisis (SRC).

Determine the underlying pathophysiology driving the acute crisis.

SRC is caused by intimal thickening of the renal arterioles leading to severe renal ischemia. This ischemia triggers massive activation of the renin-angiotensin-aldosterone system (RAAS).

Understanding that RAAS hyperactivation is the primary driver of the malignant hypertension is essential for selecting targeted pharmacotherapy.

Select the most appropriate evidence-based intervention.

An angiotensin-converting enzyme (ACE) inhibitor, such as short-acting captopril, must be initiated immediately.

ACE inhibitors directly block the RAAS cascade, reversing the primary pathophysiologic mechanism of SRC. They are life-saving and should be used even in the setting of acute kidney injury.

Key Concept

Scleroderma renal crisis presents with malignant hypertension, acute kidney injury, and microangiopathic hemolytic anemia. It is a life-threatening emergency that must be treated immediately with an ACE inhibitor (e.g., captopril) to reverse massive RAAS activation.

Question 1342Question →

A $62$ -year-old woman arrives at the emergency department reporting fevers, chills, and profound fatigue over the past $12$ hours. She is currently undergoing multi-agent chemotherapy for diffuse large B-cell lymphoma; her last infusion was $10$ days ago. Her temperature is $38.9^\circ\text{C}$ ( $102.0^\circ\text{F}$ ), blood pressure is $112/72\text{ mm Hg}$ , pulse is $95\text{/min}$ , and respiratory rate is $16\text{/min}$ . Physical examination reveals a totally implanted central venous access device in her right chest with no surrounding erythema, induration, or tenderness. Lungs are clear to auscultation. There are no skin rashes or oral ulcers.

Laboratory results are as follows:

Laboratory test	Result
Hemoglobin	$8.8\text{ g/dL}$
Platelets	$95,000\text{/mm}^3$
Leukocytes	$600\text{/mm}^3$
Segmented neutrophils	$15\%$
Band forms	$5\%$
Creatinine	$1.1\text{ mg/dL}$
Total bilirubin	$0.9\text{ mg/dL}$

A chest radiograph shows no focal consolidation.

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

Obtain blood cultures and initiate oral ciprofloxacin and amoxicillin-clavulanate

Administer filgrastim and discharge with close outpatient follow-up

Obtain blood cultures and initiate intravenous cefepime

Initiate intravenous vancomycin and amphotericin B

Withhold antimicrobial therapy until blood culture results identify a specific organism

Show answer & explanation

Answer: Obtain blood cultures and initiate intravenous cefepime

Answer

The most appropriate next step is to obtain blood cultures and immediately initiate intravenous cefepime.

The correct answer involves obtaining blood cultures and immediately starting an intravenous antipseudomonal beta-lactam, such as cefepime. Febrile neutropenia is a medical emergency defined by an absolute neutrophil count (ANC) of less than

500\text{/mm}^3

and a single oral temperature of

\geq 38.3^\circ\text{C}

(

101.0^\circ\text{F}

) or

\geq 38.0^\circ\text{C}

(

100.4^\circ\text{F}

) sustained over

1

hour. This patient's ANC is

120\text{/mm}^3

(

600 \times 0.20

). Due to the high risk of rapid clinical deterioration from bacterial sepsis (particularly Pseudomonas aeruginosa), prompt initiation of empiric broad-spectrum intravenous antibiotics is mandated. Cefepime, meropenem, or piperacillin-tazobactam are the standard of care for high-risk patients.

Step-by-Step Solution

Calculate the Absolute Neutrophil Count (ANC).

ANC is

120\text{/mm}^3

(Total Leukocytes

600 \times 0.20

[segmented + bands]).

To confirm the presence of profound neutropenia, which is defined as an ANC less than

500\text{/mm}^3

Identify the clinical syndrome based on the presentation.

The patient has febrile neutropenia.

The patient has a single oral temperature of

38.9^\circ\text{C}

concurrent with severe neutropenia.

Risk-stratify the patient to determine the appropriate treatment setting and route.

This is a high-risk presentation.

Patients with hematologic malignancies undergoing active multi-agent chemotherapy who develop profound neutropenia are automatically classified as high-risk and require inpatient intravenous management.

Select the appropriate empirical antimicrobial therapy.

Intravenous cefepime.

Guidelines mandate immediate empiric monotherapy with an antipseudomonal beta-lactam (e.g., cefepime, meropenem, or piperacillin-tazobactam). Additional coverage with vancomycin is not indicated because there is no hemodynamic instability, port infection, or severe mucositis.

Key Concept

High-risk febrile neutropenia is an oncologic emergency that requires immediate blood cultures followed by prompt initiation of an intravenous antipseudomonal beta-lactam.

Question 1343Question →

A 48-year-old woman comes to the emergency department complaining of a severe, throbbing headache, blurred vision, and mild shortness of breath that began $2$ days ago. She has a $4$ -year history of diffuse cutaneous systemic sclerosis. Her home medications include mycophenolate mofetil and omeprazole. In the emergency department, her blood pressure is $220/125$ mmHg, pulse is $98$ /min, and respiratory rate is $18$ /min. Physical examination reveals tight, thickened skin over her face, trunk, and proximal extremities. Funduscopic examination shows bilateral papilledema and flame-shaped hemorrhages. Lung auscultation reveals bibasilar crackles.

Laboratory evaluation:
Hemoglobin: $8.9$ g/dL
Platelets: $95,000$ /mm $^3$
Creatinine: $2.7$ mg/dL (baseline $0.8$ mg/dL)
Peripheral blood smear: 3-4 schistocytes per high-power field

Which of the following is the most appropriate initial pharmacological treatment for this patient's current condition?

Oral captopril

Intravenous labetalol

Intravenous methylprednisolone

Plasma exchange

Intravenous sodium nitroprusside

Show answer & explanation

Answer: Oral captopril

Answer

Oral captopril

The patient's presentation of malignant hypertension, acute kidney injury, and microangiopathic hemolytic anemia (schistocytes, thrombocytopenia) in the setting of diffuse cutaneous systemic sclerosis is classic for scleroderma renal crisis (SRC). SRC is caused by marked intimal proliferation of renal arterioles leading to decreased renal perfusion, which triggers massive activation of the renin-angiotensin-aldosterone system (RAAS). This creates a vicious cycle of severe hypertension and further renal vasoconstriction. The cornerstone of management is rapid RAAS blockade using a short-acting ACE inhibitor, specifically oral captopril. Importantly, ACE inhibitors must be initiated immediately, even in the setting of acute kidney injury and an elevated creatinine, as they uniquely reverse the underlying pathophysiologic mechanism and offer the best chance for renal recovery.

Step-by-Step Solution

Identify the primary diagnosis based on the clinical presentation and history.

The patient has systemic sclerosis and presents with malignant hypertension, acute kidney injury, and microangiopathic hemolytic anemia (MAHA), establishing the diagnosis of scleroderma renal crisis (SRC).

Recognizing the complication is essential to selecting the targeted therapy, as SRC management differs from generic hypertensive emergencies.

Determine the underlying pathophysiology driving the crisis.

SRC is driven by massive activation of the renin-angiotensin-aldosterone system (RAAS) causing severe renal vasoconstriction.

Understanding the mechanism dictates that the therapy must directly inhibit this pathway.

Select the appropriate pharmacotherapy to counteract the mechanism.

An angiotensin-converting enzyme (ACE) inhibitor, specifically captopril, is selected.

ACE inhibitors are uniquely effective in reversing the RAAS hyperactivation and are indicated even in the presence of acute kidney injury.

Key Concept

Scleroderma renal crisis presents with acute oliguric renal failure and malignant hypertension, and the first-line, life-saving treatment is immediate administration of an ACE inhibitor (captopril) regardless of the elevated serum creatinine.

Question 1344Question →

A 31-year-old man returns to the clinic for a follow-up regarding chronic lower back pain. He first developed the pain $18$ months ago. It is characteristically worse in the morning and improves with exercise. Three months ago, he was diagnosed with ankylosing spondylitis based on classic clinical findings and evidence of bilateral sacroiliitis on pelvic radiography. Over the past 3 months, he has undergone consecutive, continuous trials of naproxen and ibuprofen at maximum tolerated doses, along with a daily physical therapy regimen. Today, he reports no significant improvement in his symptoms, complaining of persistent spinal stiffness that lasts for up to $2$ hours every morning. He denies any peripheral joint pain, swelling, eye redness, or gastrointestinal symptoms. Vital signs are within normal limits. Physical examination reveals restricted lumbar flexion and tenderness over the sacroiliac joints. Laboratory studies show an erythrocyte sedimentation rate of $45 \text{ mm/h}$ (Reference: $< 15 \text{ mm/h}$ ) and a C-reactive protein of $22 \text{ mg/L}$ (Reference: $< 3 \text{ mg/L}$ ). Which of the following is the most appropriate next step in the management of this patient's condition?

Add oral methotrexate

Prescribe a tapering dose of oral prednisone

Initiate therapy with etanercept

Add oral sulfasalazine

Obtain magnetic resonance imaging of the sacroiliac joints

Show answer & explanation

Answer: Initiate therapy with etanercept

Answer

Initiate therapy with etanercept

The correct action is to initiate a biologic agent, such as a tumor necrosis factor (TNF) alpha inhibitor (e.g., etanercept, adalimumab, infliximab) or an IL-17 inhibitor. This patient has active ankylosing spondylitis with purely axial involvement that has failed to improve after continuous, adequate trials of multiple nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs are the first-line pharmacotherapy for symptomatic relief; however, if disease activity remains high despite an adequate trial (typically at least 2-4 weeks each of two different NSAIDs), biologic disease-modifying antirheumatic drugs (DMARDs) are indicated to reduce inflammation, improve mobility, and potentially slow radiographic progression.

Step-by-Step Solution

Identify the patient's diagnosis and current disease phenotype.

The patient has confirmed ankylosing spondylitis with isolated axial symptoms (morning stiffness, limited lumbar flexion) and elevated inflammatory markers, with no peripheral joint involvement.

Understanding the clinical phenotype (axial versus peripheral) is necessary to guide therapeutic decisions in spondyloarthropathies.

Evaluate the patient's prior treatment and response.

He has failed continuous trials of two different NSAIDs (naproxen and ibuprofen) at maximum tolerated doses over a 3-month period, alongside physical therapy.

Guidelines require an adequate trial of at least two NSAIDs before escalating therapy for active ankylosing spondylitis.

Determine the appropriate escalation of therapy for purely axial disease.

A biologic DMARD, specifically a TNF-alpha inhibitor (e.g., etanercept) or an IL-17 inhibitor, is indicated.

Conventional synthetic DMARDs (methotrexate, sulfasalazine) are ineffective for axial disease. Biologics are the standard next step to control inflammation and improve functional status.

Key Concept

In patients with ankylosing spondylitis who have purely axial disease and fail to respond to continuous NSAID therapy, the most appropriate next step in management is the initiation of a TNF-alpha inhibitor (e.g., etanercept, adalimumab) or an IL-17 inhibitor. Conventional DMARDs (methotrexate, sulfasalazine) are ineffective for axial disease.

Question 1345Question →

Correlate the following nuanced infectious disease presentations and resistance profiles with their optimal pharmacologic management.

Click a left item, then click its matching right item

Show answer & explanation

Answer

The correct matches align specific pathogen vulnerabilities and resistances with targeted therapies: Post-neurosurgical meningitis requires MRSA and Pseudomonas coverage (vancomycin + cefepime); B. cepacia intrinsically requires TMP-SMX; Cefepime lacks anaerobic coverage for Bacteroides, necessitating metronidazole; V. vulnificus in cirrhosis demands ceftriaxone + doxycycline; and ESBL pyelonephritis in pregnancy is safely managed with ertapenem.

Each pairing tests a critical exception or specific rule in antimicrobial stewardship. Healthcare-associated central nervous system infections demand specific antipseudomonal and MRSA coverage. Pathogens like Burkholderia cepacia and ESBL-producing E. coli harbor distinct resistance profiles that render standard empiric therapies ineffective, necessitating TMP-SMX and carbapenems, respectively. Furthermore, understanding the precise spectrum of broad-spectrum agents (such as cefepime's lack of anaerobic efficacy) and the synergistic regimens required for unique environmental exposures (like Vibrio vulnificus) is essential for preventing adverse clinical outcomes.

Step-by-Step Solution

Analyze the post-craniectomy meningitis presentation.

Identify the necessity for nosocomial central nervous system coverage.

Hospital-acquired meningitis requires targeting MRSA and Pseudomonas aeruginosa, which are not covered by standard community-acquired regimens like ceftriaxone.

Evaluate the cystic fibrosis exacerbation caused by B. cepacia.

Select trimethoprim-sulfamethoxazole.

This organism possesses intrinsic resistance to many standard beta-lactams and aminoglycosides, making TMP-SMX the definitive first-line agent.

Assess the failing febrile neutropenia regimen in the setting of B. fragilis bacteremia.

Identify a critical gap in anaerobic coverage.

While cefepime provides excellent antipseudomonal coverage, it is ineffective against gut anaerobes like Bacteroides, requiring the addition of metronidazole.

Diagnose the saltwater-associated hemorrhagic bullae in a cirrhotic host.

Recognize severe Vibrio vulnificus infection.

This highly lethal pathogen requires synergistic coverage with a third-generation cephalosporin and a tetracycline derivative.

Determine the appropriate therapy for ESBL pyelonephritis during pregnancy.

Select ertapenem.

ESBL-producing organisms require a carbapenem for eradication, and ertapenem is highly effective and generally safe to administer during pregnancy.

Key Concept

Antimicrobial stewardship and targeted drug selection based on complex host factors, environmental exposure history, and intrinsic or acquired pathogen resistance profiles.

Question 1346Question →

Evaluate the following patients presenting with acute electrolyte abnormalities. Match each patient's clinical presentation and laboratory findings with the most appropriate immediate therapeutic intervention.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Hyperkalemia with ECG changes requires calcium gluconate; severe hypokalemia requires IV potassium; severe hypercalcemia requires isotonic saline and calcitonin; and severe symptomatic hyponatremia with seizures requires 3% hypertonic saline.

Each clinical presentation represents a distinct, life-threatening electrolyte emergency requiring a specific targeted intervention to prevent irreversible morbidity or mortality.

Step-by-Step Solution

Analyze the first clinical presentation (altered mental status, peaked T waves, QRS widening).

Identify severe hyperkalemia with cardiac toxicity.

QRS widening indicates an imminent risk of ventricular fibrillation, mandating immediate cardiac membrane stabilization.

Analyze the second clinical presentation (muscle weakness, U waves, potassium 2.2 mEq/L).

Identify severe symptomatic hypokalemia.

Profound hypokalemia with ECG changes requires immediate replacement to prevent arrhythmias and respiratory muscle failure.

Analyze the third clinical presentation (lethargy, constipation, calcium 14.5 mg/dL).

Identify severe symptomatic hypercalcemia.

Calcium levels >14 mg/dL cause severe neurologic and renal dysfunction, requiring rapid reduction through volume expansion and calcitonin.

Analyze the fourth clinical presentation (seizures, sodium 112 mEq/L after a marathon).

Identify severe symptomatic hyponatremia (exercise-associated hyponatremic encephalopathy).

Active seizures in the setting of severe hyponatremia indicate critical cerebral edema, necessitating hyperosmolar therapy to shift fluid out of the brain.

Key Concept

Acute Management of Electrolyte Emergencies

Question 1347Question →

Match each clinical exposure scenario with the most appropriate first-line post-exposure prophylaxis (PEP) or immediate management strategy.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Meningococcal exposure matches with ciprofloxacin/rifampin/ceftriaxone; HIV exposure matches with 3-drug antiretroviral therapy; Tick bite (>36 hours) matches with single-dose doxycycline; Bat exposure matches with rabies immune globulin and vaccine.

Each correct pairing reflects the standard of care guidelines for post-exposure prophylaxis in infectious diseases. Preventing disease after exposure relies on targeting the specific organism's vulnerabilities before it establishes a systemic infection.

Step-by-Step Solution

Analyze each exposure scenario to identify the specific high-risk pathogen involved.

Pathogens identified: Neisseria meningitidis, Human Immunodeficiency Virus (HIV), Borrelia burgdorferi, and Rabies virus.

Different pathogens have entirely distinct pathophysiologies and modes of transmission, dictating specific prophylaxis guidelines.

Select the guideline-concordant prophylactic agent for each pathogen.

Meningococcus requires antibiotics to clear carriage (ciprofloxacin). HIV requires ART to prevent viral integration. Lyme requires a tetracycline to abort spirochete replication. Rabies requires immediate passive and active immunization to prevent fatal encephalitis.

Applying the correct targeted therapy rapidly reduces the risk of disease manifestation and prevents the misuse of inappropriate antimicrobials.

Key Concept

Identifying appropriate post-exposure prophylaxis (PEP) regimens for common high-risk infectious disease exposures.

Estimated Time:1m 0s

Question 1348Question →

Match each clinical scenario describing a high-risk infectious disease exposure with the most appropriate post-exposure prophylaxis (PEP) regimen.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Match the specific exposure to its guideline-directed prophylaxis: Unvaccinated HBV exposure requires HBIG and vaccine; meningococcal close contact requires ceftriaxone, ciprofloxacin, or rifampin; potential bat exposure requires RIG and rabies vaccine; and high-risk occupational HIV exposure requires a 3-drug antiretroviral regimen.

Appropriate post-exposure prophylaxis depends entirely on the specific pathogen, the nature of the exposure, and the host's prior immunity. Bacterial exposures like Neisseria meningitidis require short-course antibiotics to eliminate carriage. Viral exposures like HIV require multi-drug antiretroviral therapy to prevent viral replication and integration. Pathogens with potentially lethal outcomes in naive hosts (Rabies, HBV) require a combination of immune globulin (for immediate passive protection) and vaccination (for lasting active immunity).

Step-by-Step Solution

Evaluate the source patient and the type of exposure.

Identify the specific pathogen risk (HBV, Neisseria meningitidis, Rabies virus, HIV).

Post-exposure prophylaxis regimens are highly pathogen-specific.

Assess the immune status of the exposed individual.

Determine if passive immunity, active immunity, or both are required.

Vaccinated individuals may need different interventions compared to naive individuals (e.g., an unvaccinated person exposed to HBV needs both HBIG and the vaccine).

Select the appropriate pharmacologic or immunologic intervention.

Match the exposure to the current guideline-directed prophylaxis regimen.

Timely administration of the correct regimen prevents disease transmission and progression.

Key Concept

Post-exposure prophylaxis (PEP) guidelines for high-risk infectious exposures

Question 1349Question →

Match each clinical and laboratory presentation with the most likely underlying hematologic diagnosis.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Properly align each clinical vignette with its corresponding hematologic malignancy or disorder based on unique laboratory and symptomatic clues.

Each diagnosis uniquely matches a constellation of symptoms and lab findings. TTP is defined by MAHA and thrombocytopenia with normal coagulation parameters. Polycythemia vera presents with primary erythrocytosis (low EPO) and aquagenic pruritus. ITP presents with isolated thrombocytopenia in the absence of other systemic illnesses. CML is a myeloproliferative disorder characterized by massive splenomegaly, prominent basophilia, and a low LAP score.

Step-by-Step Solution

Analyze the first vignette for the classic pentad.

Identified microangiopathic hemolytic anemia (MAHA), thrombocytopenia, renal failure, neurologic changes, and fever.

These concurrent findings represent Thrombotic thrombocytopenic purpura (TTP).

Evaluate the second vignette for signs of myeloproliferation and specific symptoms.

Elevated hematocrit, WBCs, and platelets with low EPO and aquagenic pruritus.

These are hallmark features of Polycythemia vera, caused by autonomous marrow proliferation.

Assess the third vignette for isolated lab abnormalities.

Isolated thrombocytopenia with normal coagulation studies and no other cytopenias.

This presentation strongly suggests Immune thrombocytopenia (ITP), a diagnosis of exclusion.

Review the fourth vignette for leukocytosis and splenomegaly.

High WBC count with left shift, basophilia, and low LAP score.

A low LAP score and the presence of basophilia differentiate Chronic myeloid leukemia (CML) from severe infection (leukemoid reaction).

Key Concept

Accurate diagnosis of hematologic disorders relies on recognizing pathognomonic clinical features paired with specific laboratory abnormalities, such as smear findings (schistocytes, megathrombocytes) or functional assays (LAP score, EPO levels).

Question 1350Question →

A 64-year-old man is evaluated in the hospital for a new-onset fever. He was admitted 12 days ago for severe acute pancreatitis complicated by a prolonged ileus, which necessitated the placement of a right internal jugular central venous catheter for total parenteral nutrition. Yesterday, he developed a fever of 39.2°C (102.6°F) and chills. Blood cultures were drawn, and empiric intravenous vancomycin and piperacillin-tazobactam were initiated. Today, his temperature is 37.6°C (99.7°F), blood pressure is 118/76 mm Hg, and pulse is 88/min. The central venous catheter has been removed. Blood cultures from both the catheter tip and a peripheral vein are growing *Enterobacter cloacae*. Antimicrobial susceptibility testing results are as follows:

Antimicrobial	Interpretation
Ampicillin	Resistant
Cefazolin	Resistant
Ceftriaxone	Susceptible
Cefepime	Susceptible
Piperacillin-tazobactam	Susceptible
Meropenem	Susceptible
Ciprofloxacin	Susceptible

Which of the following is the most appropriate next step in this patient's pharmacotherapy?

Continue intravenous piperacillin-tazobactam

Change to intravenous ceftriaxone

Change to intravenous cefepime

Change to intravenous meropenem

Change to oral ciprofloxacin

Show answer & explanation

Answer: Change to intravenous cefepime

Answer

The most appropriate next step is to change to intravenous cefepime.

The correct decision is to change therapy to intravenous cefepime. *Enterobacter cloacae* is a classic member of the organisms (along with *Citrobacter freundii* and *Klebsiella aerogenes*) that harbor a chromosomal AmpC beta-lactamase gene. Exposure to third-generation cephalosporins (such as ceftriaxone) can induce the hyperproduction, or derepression, of this enzyme. This leads to profound clinical failure even if the isolate initially tests susceptible in vitro, meaning third-generation cephalosporins are contraindicated for invasive AmpC infections. Cefepime, a fourth-generation cephalosporin, is a weak inducer of AmpC and structurally withstands hydrolysis by the enzyme, making it the preferred definitive therapy. While meropenem is also effective, cefepime is favored to maintain good antibiotic stewardship and spare carbapenems.

Step-by-Step Solution

Identify the organism and its characteristic resistance mechanisms.

The organism is Enterobacter cloacae, a known producer of chromosomal AmpC beta-lactamase.

Recognizing organisms with inducible AmpC (e.g., Enterobacter, Klebsiella aerogenes, Citrobacter freundii) is critical because in vitro susceptibility does not always equal in vivo efficacy.

Evaluate the susceptibility report in the context of AmpC production.

Although ceftriaxone and piperacillin-tazobactam test susceptible in vitro, they are associated with high failure rates in vivo due to AmpC derepression and weak inhibition, respectively.

Standard automated susceptibility testing does not account for the high likelihood of resistance emerging during therapy with specific beta-lactams.

Select the most appropriate definitive therapy balancing efficacy and antibiotic stewardship.

Cefepime is chosen because it is stable against AmpC hydrolysis and is narrower in spectrum than meropenem.

Guidelines recommend cefepime for invasive AmpC infections, reserving carbapenems to prevent the emergence of carbapenem-resistant Enterobacterales.

Key Concept

Definitive management of severe infections caused by organisms with inducible AmpC beta-lactamase (e.g., Enterobacter cloacae) requires cefepime or a carbapenem; third-generation cephalosporins and piperacillin-tazobactam should be avoided despite in vitro susceptibility.

Question 1351Question →

A 42-year-old man comes to the clinic reporting a 4-month history of progressive fatigue, generalized weakness, and decreased libido. He also notes occasional dull, morning headaches that improve as the day progresses. He has no significant past medical history and takes no medications. Vital signs show a heart rate of $56$ /min and a blood pressure of $105/65$ mm Hg. Physical examination reveals delayed relaxation of deep tendon reflexes. His testes are soft and measure $12$ mL bilaterally. Visual fields are full to confrontation. Laboratory studies show:

Laboratory Test	Result	Reference Range
Thyroid-stimulating hormone (TSH)	$2.4$ $\mu$ U/mL	$0.4-4.2$ $\mu$ U/mL
Free thyroxine (T4)	$0.5$ ng/dL	$0.9-1.7$ ng/dL

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

Measure morning serum cortisol level

Initiate oral levothyroxine

Measure serum thyroid peroxidase antibodies

Obtain an ultrasound of the thyroid gland

Schedule a follow-up for repeat thyroid function testing in 6 weeks

Show answer & explanation

Answer: Measure morning serum cortisol level

Answer

The correct answer is to measure a morning serum cortisol level to rule out concurrent central adrenal insufficiency before treating the central hypothyroidism.

The correct answer addresses the critical procedural rule in endocrinology: when a patient presents with central hypothyroidism (low free T4, inappropriately normal/low TSH), panhypopituitarism must be suspected. The adrenal axis must be evaluated with a morning serum cortisol level before initiating thyroid hormone replacement. Giving levothyroxine accelerates cortisol metabolism, which can precipitate acute adrenal crisis if the patient has concurrent untreated central adrenal insufficiency.

Step-by-Step Solution

Interpret the thyroid function tests.

The patient has a low free T4 level but an inappropriately normal TSH.

This specific pattern differentiates central (secondary) hypothyroidism from primary hypothyroidism (where TSH would be elevated).

Correlate laboratory findings with the clinical presentation.

The combination of central hypothyroidism, decreased libido with soft testes (suggesting central hypogonadism), and morning headaches points to panhypopituitarism caused by a pituitary mass.

Establishing the etiology ensures that all potentially affected endocrine axes are considered.

Determine the safest immediate management step.

Order a morning serum cortisol level prior to initiating levothyroxine therapy.

Administering thyroid hormone increases the metabolic clearance of cortisol. If concurrent adrenal insufficiency is present and unrecognized, starting levothyroxine can precipitate a fatal adrenal crisis.

Key Concept

In patients diagnosed with central hypothyroidism, it is essential to evaluate for concurrent central adrenal insufficiency (e.g., via 8:00 AM serum cortisol) before initiating levothyroxine to avoid precipitating an adrenal crisis.

Estimated Time:1m 30s

Question 1352Question →

An 82-year-old man resides in an assisted living facility and is brought to the emergency department after nursing staff noticed him becoming progressively more lethargic over the past 24 hours. Upon evaluation, his temperature is 39.1°C (102.4°F), blood pressure is 105/65 mm Hg, and heart rate is 118/min. The patient is arousable only to painful stimuli. Neurologic examination reveals prominent resistance to passive neck flexion and a diminished gag reflex, alongside symmetric hyperreflexia in the lower extremities. Arrange the following interventions in the most appropriate sequential order for managing this patient.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence for managing suspected bacterial meningitis with indications for preliminary neuroimaging is: 1) Draw peripheral blood cultures, 2) Initiate intravenous dexamethasone, ceftriaxone, vancomycin, and ampicillin, 3) Obtain a non-contrast CT scan of the head, 4) Perform a diagnostic lumbar puncture.

The standard algorithmic approach to a patient with suspected acute bacterial meningitis depends heavily on whether indications for a preliminary CT scan are present. Indications include age greater than 60, immunocompromise, history of central nervous system disease, new-onset seizures, severely altered mental status, and focal neurologic deficits. Because this elderly patient has a severely depressed level of consciousness, he requires a CT scan to rule out elevated intracranial pressure before a lumbar puncture can be safely performed. However, neuroimaging takes time, and delaying treatment in bacterial meningitis significantly increases mortality. Therefore, the most critical principle is to draw blood cultures and immediately administer empiric antibiotics (ceftriaxone, vancomycin, and ampicillin for Listeria coverage in the elderly) along with adjunctive dexamethasone. Once therapy is infusing, the patient can be transported for the CT scan, followed finally by the lumbar puncture.

Step-by-Step Solution

Assess the clinical presentation to synthesize the primary diagnosis.

The combination of severe lethargy, high fever, and nuchal rigidity in an elderly patient is highly concerning for acute bacterial meningitis.

Rapid recognition of this infectious and neurologic emergency is critical for initiating the time-sensitive management pathway.

Determine if there are contraindications to an immediate diagnostic lumbar puncture.

The patient's severely depressed level of consciousness (arousable only to pain) is a strict indication for neuroimaging prior to the procedure.

Performing a lumbar puncture in the setting of elevated intracranial pressure can precipitate fatal cerebral herniation.

Sequence the stabilization, medical therapy, and diagnostic workup.

Blood cultures must be obtained first, immediately followed by empiric antibiotics and steroids. The CT scan is performed next, followed by the lumbar puncture.

Delaying antimicrobial therapy to wait for a CT scan dramatically increases mortality. Cultures must precede antibiotics, and antibiotics must precede imaging.

Key Concept

Algorithmic management of suspected acute bacterial meningitis with high-risk neurologic features

Question 1353Question →

A $66$ -year-old male is evaluated in the intensive care unit for sudden-onset hypotension. He was intubated $6$ hours ago for hypercapnic respiratory failure secondary to a severe chronic obstructive pulmonary disease exacerbation. He has a history of right ventricular hypertrophy. The patient is deeply sedated. Vital signs are temperature $37.4^\circ\text{C}$ ( $99.3^\circ\text{F}$ ), blood pressure $74/46$ mm Hg, heart rate $136$ /min, and respiratory rate $22$ /min (set by ventilator). Oxygen saturation is $92\%$ on a fractional inspired oxygen ( $\text{FiO}_2$ ) of $0.40$ .

Current ventilator settings in volume-assist control mode are:
Tidal volume: $550$ mL ( $8$ mL/kg ideal body weight)
Respiratory rate: $22$ /min
Inspiratory flow rate: $50$ L/min
Positive end-expiratory pressure (PEEP): $5$ cm $\text{H}_2\text{O}$

Physical examination demonstrates markedly distended jugular veins and symmetrically distant breath sounds with a prolonged expiratory phase. The ventilator displays a peak inspiratory pressure of $58$ cm $\text{H}_2\text{O}$ and a plateau pressure of $24$ cm $\text{H}_2\text{O}$ . The flow-time scalar shows that expiratory flow remains negative and does not return to the zero baseline before the delivery of the next mandatory breath.

An arterial blood gas analysis reveals:
pH: $7.26$
$\text{PaCO}_2$ : $68$ mm Hg
$\text{PaO}_2$ : $66$ mm Hg
$\text{HCO}_3^-$ : $30$ mEq/L

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

Administer an intravenous bolus of furosemide

Transport the patient for computed tomography pulmonary angiography

Administer broad-spectrum intravenous antibiotics

Temporarily disconnect the endotracheal tube from the ventilator circuit

Administer intravenous sodium bicarbonate

Show answer & explanation

Answer: Temporarily disconnect the endotracheal tube from the ventilator circuit

Answer

The most appropriate immediate next step is to temporarily disconnect the endotracheal tube from the ventilator circuit.

The correct answer is to temporarily disconnect the endotracheal tube from the ventilator circuit. This patient's flow-time scalar reveals that expiratory flow does not return to zero before the next breath, confirming dynamic hyperinflation (auto-PEEP). The high peak inspiratory pressure with a normal plateau pressure confirms a resistance problem, typical of severe obstructive lung disease. The trapped air progressively increases intrathoracic pressure, which impedes venous return to the right heart. This leads to obstructive shock, presenting with severe hypotension, tachycardia, and jugular venous distention. The immediate, life-saving intervention is to disconnect the patient from the ventilator, allowing the trapped air to escape and immediately restoring venous return. Afterward, ventilator settings should be adjusted to increase expiratory time.

Step-by-Step Solution

Interpret the ventilator graphics and airway pressures.

The high peak inspiratory pressure with a normal plateau pressure indicates high airway resistance. The flow-time scalar failing to reach zero confirms dynamic hyperinflation (auto-PEEP).

Identifying the mechanical abnormality is necessary to understand the cause of the sudden decompensation.

Correlate the mechanical findings with the patient's hemodynamics.

The trapped intrathoracic air increases intrathoracic pressure, which severely reduces venous return, leading to obstructive shock characterized by hypotension, tachycardia, and distended jugular veins.

Differentiating obstructive shock from cardiogenic or distributive shock dictates the immediate life-saving intervention.

Determine the appropriate mechanical intervention.

Temporarily disconnecting the patient from the ventilator allows for prolonged, unobstructed exhalation of the trapped air.

This rapidly decreases intrathoracic pressure, restores venous return to the right heart, and stabilizes the patient's blood pressure.

Key Concept

Recognition and acute management of dynamic hyperinflation (auto-PEEP) causing obstructive shock in mechanically ventilated patients.

Question 1354Question →

A 54-year-old woman is evaluated in the intensive care unit for worsening kidney function. She was admitted four days ago for sepsis secondary to a complicated urinary tract infection and required aggressive fluid resuscitation and vasopressor support. Her urine output has steadily decreased over the past 24 hours.

Current laboratory results are as follows:
Serum sodium: 140 mEq/L
Serum creatinine: 2.1 mg/dL
Urine sodium: 60 mEq/L
Urine creatinine: 30 mg/dL

Based on these findings, what is this patient's fractional excretion of sodium (in percent)?

Show answer & explanation

Answer: 3

Answer

The fractional excretion of sodium (FeNa) is 3%. The calculation is derived using the formula

FeNa = (U_{Na} \times P_{Cr}) / (P_{Na} \times U_{Cr}) \times 100

. Plugging in the values gives

(60 \times 2.1) / (140 \times 30) \times 100

, which simplifies to

126 / 4200 \times 100 = 3

. In this clinical context, a FeNa greater than 2% strongly points toward acute tubular necrosis (ATN) induced by previous ischemic shock, confirming intrinsic renal damage rather than a simple prerenal state.

Step-by-Step Solution

Identify the standard formula for calculating Fractional Excretion of Sodium (FeNa).

FeNa = \frac{U_{Na} \times P_{Cr}}{P_{Na} \times U_{Cr}} \times 100

This formula relates the clearance of sodium to the clearance of creatinine to differentiate prerenal from intrinsic acute kidney injury.

Extract the specific laboratory values from the clinical vignette.

Urine sodium (

U_{Na}

) = 60, Plasma/Serum creatinine (

P_{Cr}

) = 2.1, Plasma/Serum sodium (

P_{Na}

) = 140, Urine creatinine (

U_{Cr}

) = 30.

These variables must be precisely assigned to avoid calculation errors.

Substitute the values into the formula and solve.

FeNa = \frac{60 \times 2.1}{140 \times 30} \times 100 = \frac{126}{4200} \times 100 = 0.03 \times 100 = 3

Solving the arithmetic yields the exact physiological percentage.

Key Concept

Calculation of Fractional Excretion of Sodium (FeNa)

Question 1355Question →

A 32-year-old woman comes to the clinic for evaluation of profound generalized muscle weakness that has progressively worsened over the past three days. She also reports a one-year history of a gritty sensation in her eyes and feeling like she constantly needs to drink water because her mouth is extremely dry. Last year, she was treated in the emergency department for severe left flank pain, which was attributed to a kidney stone. Vitals are within normal limits. Physical examination reveals a dry oral mucosa and bilaterally enlarged parotid glands. Laboratory results are as follows:

Serum chemistry:
Sodium: $139 \text{ mEq/L}$
Potassium: $2.6 \text{ mEq/L}$
Chloride: $114 \text{ mEq/L}$
Bicarbonate: $13 \text{ mEq/L}$
Blood urea nitrogen: $14 \text{ mg/dL}$
Creatinine: $0.9 \text{ mg/dL}$

Arterial blood gas (room air):
pH: $7.28$
pCO_2: $28 \text{ mmHg}$

Urinalysis:
pH: $6.8$
Specific gravity: $1.010$
Blood: Negative
Protein: Negative
Glucose: Negative

Which of the following is the most likely primary mechanism responsible for this patient's current acid-base and electrolyte derangements?

Impaired apical secretion of hydrogen ions in the collecting duct

Defective reabsorption of filtered bicarbonate in the proximal tubule

Reduced responsiveness of the principal cells to aldosterone

Increased gastrointestinal excretion of bicarbonate-rich fluids

Accumulation of unmeasured endogenous organic anions

Show answer & explanation

Answer: Impaired apical secretion of hydrogen ions in the collecting duct

Answer

The correct answer is impaired apical secretion of hydrogen ions in the collecting duct, which is the pathophysiologic mechanism of Type 1 (distal) renal tubular acidosis.

This patient has a normal anion gap metabolic acidosis (Anion Gap =

139 - 114 - 13 = 12 \text{ mEq/L}

) with severe hypokalemia and an inappropriately alkaline urine pH (

6.8

). Coupled with a history of recurrent kidney stones and symptoms highly suggestive of Sjögren syndrome (dry mouth, gritty eyes, parotid enlargement), this presentation is pathognomonic for Type 1 (distal) renal tubular acidosis (RTA).

Type 1 RTA is caused by an inability of the alpha-intercalated cells in the distal collecting duct to secrete hydrogen (

H^+

) ions into the tubular lumen. This primary defect leads to impaired urinary acidification (urine pH is almost always

> 5.5

), decreased bicarbonate regeneration, and obligate potassium wasting (as potassium is secreted in excess to maintain electroneutrality when

H^+

cannot be secreted). The persistently alkaline urine, combined with reduced urinary citrate excretion (hypocitraturia), heavily predisposes these patients to the formation of calcium phosphate kidney stones.

Step-by-Step Solution

Calculate the serum anion gap to determine the primary acid-base disorder.

Anion Gap =

Na^+ - (Cl^- + HCO_3^-) = 139 - (114 + 13) = 12 \text{ mEq/L}

. This indicates a normal anion gap metabolic acidosis (NAGMA).

Categorizing the metabolic acidosis as normal vs. high anion gap is the mandatory first step in narrowing the differential diagnosis.

Evaluate the serum potassium level in the context of the NAGMA.

The potassium is severely low (

2.6 \text{ mEq/L}

Hypokalemia rules out Type 4 RTA (which features hyperkalemia) and points toward gastrointestinal losses or Type 1/Type 2 RTA.

Analyze the urinalysis, specifically the urine pH.

The urine pH is

6.8

, which is inappropriately alkaline in the setting of severe systemic acidosis.

A urine pH

> 5.5

during systemic acidemia indicates a failure of distal renal acidification, differentiating Type 1 RTA from diarrhea and Type 2 RTA (which both typically have a urine pH

< 5.5

Correlate the laboratory findings with the clinical history to identify the underlying mechanism.

The patient has symptoms of Sjögren syndrome (sicca symptoms, parotid enlargement) and a history of kidney stones.

Type 1 RTA is highly associated with autoimmune conditions like Sjögren syndrome and characteristically causes calcium phosphate nephrolithiasis due to alkaline urine and hypocitraturia. The mechanism is a failure of alpha-intercalated cells to secrete

H^+

Key Concept

Type 1 (distal) renal tubular acidosis is characterized by a normal anion gap metabolic acidosis, severe hypokalemia, inappropriately alkaline urine (pH > 5.5), and calcium phosphate nephrolithiasis. It is caused by impaired hydrogen ion secretion by the alpha-intercalated cells of the collecting duct.

Estimated Time:1m 30s

Question 1356Question →

A 72-year-old woman is brought to the emergency department after a syncopal episode. She is currently conscious but complains of severe dizziness and chest pressure. Her blood pressure is 80/50 mm Hg, and her heart rate is 35/min. Arrange the following management steps in the most appropriate chronological sequence according to standard Advanced Cardiovascular Life Support (ACLS) guidelines for symptomatic bradycardia.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence for managing symptomatic bradycardia is: 1) Establish intravenous access and obtain a 12-lead ECG, 2) Administer a rapid intravenous dose of atropine, 3) Initiate transcutaneous pacing, and 4) Insert a temporary transvenous pacemaker.

According to the ACLS algorithm for symptomatic bradycardia, the initial step is to maintain the airway, provide oxygen if hypoxemic, establish IV access, and obtain a 12-lead ECG. Once the patient is deemed unstable (e.g., hypotension, ischemic chest discomfort), the first-line intervention is IV atropine. If atropine is ineffective, the next step is transcutaneous pacing (or IV dopamine/epinephrine infusion). If these measures fail, expert consultation for temporary transvenous pacing is indicated.

Step-by-Step Solution

Identify the clinical condition

The patient has symptomatic bradycardia with signs of hemodynamic instability (hypotension, chest pressure).

Recognizing instability dictates immediate movement down the ACLS symptomatic bradycardia algorithm.

Perform initial stabilization

Establish intravenous access and obtain a 12-lead electrocardiogram.

Before administering medications, it is crucial to ensure IV access and properly identify the underlying rhythm.

Administer first-line pharmacotherapy

Administer a rapid intravenous dose of atropine.

Atropine is the primary medication used to treat symptomatic bradycardia by exerting a vagolytic action on the atrioventricular node.

Provide second-line interventions if needed

Initiate transcutaneous pacing.

If atropine is ineffective or contraindicated, transcutaneous pacing (or chronotropic infusions) should be initiated.

Provide definitive or advanced therapy

Insert a temporary transvenous pacemaker.

If non-invasive measures fail or as a bridge to permanent pacing, expert consultation and transvenous pacing are required.

Key Concept

Advanced Cardiovascular Life Support (ACLS) Symptomatic Bradycardia Algorithm

Estimated Time:1m 0s

Question 1357Question →

A 62-year-old man comes to the clinic because of severe, excruciating pain in his right great toe that began abruptly overnight. He cannot bear weight on his right foot or tolerate the bedsheets touching his toe. His past medical history is significant for hypertension, type 2 diabetes mellitus, and stage 4 chronic kidney disease. Current medications include amlodipine, insulin glargine, and lisinopril. His temperature is 37.6°C (99.7°F), blood pressure is 135/85 mmHg, and pulse is 92/min. Physical examination reveals a markedly erythematous, swollen, warm, and exquisitely tender right first metatarsophalangeal joint. Range of motion is severely limited due to pain. Laboratory studies show a serum creatinine level of 2.6 mg/dL (baseline 2.5 mg/dL) and a serum uric acid level of 5.8 mg/dL (normal: 4.0-8.5 mg/dL). Joint aspiration yields fluid with a leukocyte count of 35,000/mm³ and negatively birefringent, needle-shaped crystals. Gram stain shows no organisms. Which of the following is the most appropriate next step in management?

Administration of intra-articular glucocorticoids

Administration of oral indomethacin

Initiation of oral allopurinol

Administration of intravenous vancomycin and ceftriaxone

Measurement of 24-hour urine uric acid excretion

Show answer & explanation

Answer: Administration of intra-articular glucocorticoids

Answer

Administration of intra-articular glucocorticoids

The correct answer is the administration of intra-articular glucocorticoids. This patient presents with classic signs of an acute gout flare, specifically podagra (acute monoarthritis of the first metatarsophalangeal joint). The diagnosis is definitively confirmed by the presence of negatively birefringent, needle-shaped monosodium urate crystals in the synovial fluid. Standard first-line therapies for an acute gout attack include NSAIDs, colchicine, and glucocorticoids. However, this patient has stage 4 chronic kidney disease (CKD). NSAIDs are strictly contraindicated in severe CKD because they inhibit prostaglandin synthesis, leading to afferent arteriolar vasoconstriction and potentially severe acute kidney injury. Colchicine must also be avoided or heavily dose-reduced in advanced renal impairment due to the high risk of fatal neuromyopathy and bone marrow suppression. Therefore, glucocorticoids are the safest option. Because this is a monoarticular flare, an intra-articular injection of glucocorticoids is preferred over systemic administration. This localized approach provides rapid relief while minimizing systemic side effects, which is particularly advantageous for this patient who also has type 2 diabetes mellitus, as systemic steroids can precipitate severe hyperglycemia.

Step-by-Step Solution

Identify the patient's primary diagnosis based on the clinical presentation and diagnostic studies.

The patient has an acute monoarthritis of the first metatarsophalangeal joint (podagra) with negatively birefringent crystals in the synovial fluid, confirming an acute gout flare.

Establishing the correct diagnosis is essential before determining the appropriate treatment pathway.

Evaluate the patient's medical history and current organ function to identify any contraindications to standard therapies.

The patient has stage 4 chronic kidney disease with a significantly elevated serum creatinine of 2.6 mg/dL.

First-line treatments for acute gout include NSAIDs, colchicine, and glucocorticoids. The choice depends heavily on patient comorbidities.

Select the safest and most effective targeted therapy based on the comorbidities.

NSAIDs and colchicine are contraindicated or highly problematic in severe chronic kidney disease. Intra-articular glucocorticoids are safe, avoid systemic side effects (especially important given his diabetes), and effectively treat monoarticular flares.

Intra-articular glucocorticoid injection provides direct local anti-inflammatory action without the risk of systemic nephrotoxicity.

Key Concept

In patients with an acute gout flare and severe chronic kidney disease, nonsteroidal anti-inflammatory drugs (NSAIDs) and colchicine are typically contraindicated, making intra-articular or systemic glucocorticoids the safest and most appropriate first-line treatment.

Estimated Time:1m 0s

Question 1358Question →

A 56-year-old man is brought to the emergency department by his wife due to a 2-day history of diffuse abdominal discomfort, subjective fever, and increasing confusion. His medical history is significant for decompensated alcohol-associated cirrhosis. He takes furosemide, spironolactone, and lactulose at home. His temperature is 38.2°C (100.8°F), blood pressure is 102/64 mmHg, pulse is 98/min, and respirations are 16/min. Physical examination demonstrates scleral icterus and multiple spider angiomas on the anterior chest. The abdomen is distended with a positive fluid wave and shifting dullness. There is diffuse, mild abdominal tenderness to palpation, but no rebound tenderness or rigidity is present. Neurologic examination reveals a coarse, flapping tremor when the patient's wrists are extended, and he is oriented to person only. Which of the following is the most appropriate next step in management?

Diagnostic paracentesis

Intravenous administration of broad-spectrum antibiotics

Immediate exploratory laparotomy

Measurement of serum thyroid-stimulating hormone

Administration of intravenous haloperidol

Show answer & explanation

Answer: Diagnostic paracentesis

Answer

The most appropriate next step in management is to perform a diagnostic paracentesis.

The correct answer is diagnostic paracentesis. This patient with decompensated cirrhosis presents with the classic triad of spontaneous bacterial peritonitis (SBP): fever, abdominal pain, and altered mental status (hepatic encephalopathy). Because SBP is highly fatal if left untreated, any patient with ascites and signs of infection or clinical deterioration requires prompt evaluation. The essential first step is diagnostic paracentesis to obtain ascitic fluid for cell count and culture. A diagnosis of SBP is established if the ascitic fluid absolute neutrophil count (ANC) is

\geq 250/mm^3

. Empiric intravenous antibiotics (e.g., a third-generation cephalosporin) should be administered immediately after the fluid is drawn, but never before, as doing so can compromise culture yield.

Step-by-Step Solution

Identify the patient's underlying condition and acute presentation.

The patient has decompensated cirrhosis with ascites, presenting with new-onset fever, abdominal pain, and hepatic encephalopathy.

Recognizing the triad of ascites, fever, and altered mental status points directly to a specific infectious complication.

Formulate the most likely diagnosis.

The most likely diagnosis is spontaneous bacterial peritonitis (SBP), which frequently precipitates hepatic encephalopathy.

SBP is a common and life-threatening infection of ascitic fluid in patients with cirrhosis.

Determine the next best step in management.

A diagnostic paracentesis must be performed immediately.

Ascitic fluid analysis (specifically looking for an absolute neutrophil count

\geq 250/mm^3

) is required to confirm the diagnosis and guide targeted antibiotic therapy.

Key Concept

Patients with cirrhosis and ascites who present with fever, abdominal pain, or altered mental status should immediately undergo diagnostic paracentesis to evaluate for spontaneous bacterial peritonitis prior to initiating empiric antibiotics.

Estimated Time:1m 0s

Question 1359Question →

A $52$ -year-old man with a history of recurrent pulmonary infections and bronchiectasis is brought to the emergency department after coughing up approximately $700$ mL of bright red blood over the past two hours. On arrival, he is in severe respiratory distress, lethargic, and coughing continuously. Vital signs show a temperature of $37.2^\circ\text{C}$ ( $99.0^\circ\text{F}$ ), blood pressure of $88/54\text{ mm Hg}$ , pulse of $128\text{/min}$ , and respiratory rate of $28\text{/min}$ . Oxygen saturation is $85\%$ on high-flow oxygen. Auscultation reveals coarse crackles and diminished breath sounds over the right hemithorax. Large-bore intravenous access is established. Arrange the following interventions in the most appropriate sequential order for the acute management of this patient's condition.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence follows the ABCs of resuscitation: secure the airway, protect the breathing (positioning), stabilize circulation, perform diagnostic bronchoscopy, and conclude with definitive embolization.

The algorithmic approach to massive hemoptysis follows standard resuscitation principles. The paramount initial step is securing the airway via endotracheal intubation to prevent asphyxiation, especially given the patient's lethargy and hypoxia. Following airway protection, the patient should be placed with the bleeding lung in the dependent position (right lateral decubitus in this case, given right-sided crackles) to protect the unaffected lung. Once the airway and breathing are managed, hemodynamic resuscitation (Circulation) with intravenous fluids and blood products is optimized. After stabilization, bronchoscopy is performed to clear clots, localize the specific bleeding site, and attempt local hemostatic maneuvers. Finally, as definitive therapy, bronchial artery embolization is performed.

Step-by-Step Solution

Secure the airway via endotracheal intubation

Prevents asphyxiation and allows for effective mechanical ventilation and suctioning.

The patient is lethargic, hypoxic, and actively bleeding into his airways, making immediate airway protection the most critical life-saving priority.

Place the patient in the right lateral decubitus position

Uses gravity to keep blood pooled in the right lung.

The right lung is the suspected source of bleeding based on localized crackles. Placing it dependent protects the healthy left lung from aspiration of blood.

Administer intravenous crystalloid and blood product resuscitation

Restores intravascular volume and improves hemodynamics.

The patient is hypotensive and tachycardic, requiring immediate cardiovascular support (the Circulation step of the ABC algorithm).

Perform urgent bronchoscopy

Visualizes the airways to precisely locate the bleeding source.

Once stabilized, bronchoscopy allows for diagnosis and initial local hemostatic interventions (e.g., balloon tamponade or cold saline lavage).

Proceed with bronchial artery embolization

Stops the arterial bleeding source permanently.

This is the gold-standard definitive treatment for massive hemoptysis when initial procedural stabilization cannot achieve permanent hemostasis.

Key Concept

The management of massive hemoptysis strictly follows the ABCs of resuscitation: Airway protection (intubation), Breathing maintenance (positioning the bleeding lung dependent), and Circulation support (fluids/blood), followed by diagnostic bronchoscopy and definitive bronchial artery embolization.

Question 1360Question →

A $67$ -year-old woman is brought to the emergency department from a skilled nursing facility due to increasing lethargy, shortness of breath, and severe, watery diarrhea for the past $48$ hours. She has a history of severe chronic obstructive pulmonary disease (COPD), heart failure with preserved ejection fraction, and recurrent urinary tract infections. Her daily medications include tiotropium, formoterol, lisinopril, and as-needed albuterol.

On presentation, she is somnolent but arousable. Temperature is $37.8^\circ\text{C}$ ( $100.0^\circ\text{F}$ ), blood pressure is $98/60\text{ mm Hg}$ , pulse is $115/\text{min}$ , and respirations are $24/\text{min}$ . Pulse oximetry shows $89\%$ on $2\text{ L/min}$ oxygen via nasal cannula.

Physical examination reveals dry mucous membranes, decreased skin turgor, and mild abdominal distension with hyperactive bowel sounds. Lung examination shows diminished breath sounds bilaterally with a prolonged expiratory phase. Cardiac examination reveals a regular tachycardia without murmurs or gallops.

Laboratory results:

Laboratory Parameter	Result	Reference Range
Leukocyte count	$11,500/\text{mm}^3$	$4,500-11,000/\text{mm}^3$
Sodium	$139 \text{ mEq/L}$	$136-145 \text{ mEq/L}$
Potassium	$3.1 \text{ mEq/L}$	$3.5-5.0 \text{ mEq/L}$
Chloride	$114 \text{ mEq/L}$	$98-106 \text{ mEq/L}$
Bicarbonate	$15 \text{ mEq/L}$	$22-28 \text{ mEq/L}$
Blood urea nitrogen	$42 \text{ mg/dL}$	$8-20 \text{ mg/dL}$
Creatinine	$1.8 \text{ mg/dL}$	$0.6-1.2 \text{ mg/dL}$

Arterial blood gas (on

2\text{ L/min}

oxygen):

Arterial Blood Gas	Result	Reference Range
pH	$7.21$	$7.35-7.45$
$\text{PaCO}_2$	$39 \text{ mm Hg}$	$35-45 \text{ mm Hg}$
$\text{PaO}_2$	$58 \text{ mm Hg}$	$75-105 \text{ mm Hg}$

A chest radiograph shows hyperinflated lungs but no focal infiltrates or signs of pulmonary edema.

In addition to aggressive intravenous fluid resuscitation, which of the following is the most appropriate next step in the management of this patient's respiratory status?

Empirical intravenous vancomycin and piperacillin-tazobactam

Intravenous sodium bicarbonate therapy

Initiation of noninvasive positive pressure ventilation

Intravenous furosemide therapy

Intravenous acetazolamide therapy

Show answer & explanation

Answer: Initiation of noninvasive positive pressure ventilation

Answer

Initiation of noninvasive positive pressure ventilation

The correct intervention is the initiation of noninvasive positive pressure ventilation (NPPV). This patient presents with a severe non-anion gap metabolic acidosis secondary to profound diarrhea. Applying Winter's formula (

\text{Expected PaCO}_2 = 1.5 \times 15 + 8 \pm 2

), her expected

\text{PaCO}_2

should be between

28.5

and

32.5 \text{ mm Hg}

. However, her actual

\text{PaCO}_2

39 \text{ mm Hg}

. Although

39 \text{ mm Hg}

falls within the standard normal reference range, in the context of a severe metabolic acidosis, it represents a profound failure of respiratory compensation (a superimposed primary respiratory acidosis). In a patient with severe COPD, this relative hypercapnia signifies acute respiratory muscle fatigue and impending frank respiratory failure. NPPV is the preferred initial management to decrease the work of breathing and improve alveolar ventilation in patients who are somnolent but arousable and capable of protecting their airway.

Step-by-Step Solution

Identify the primary acid-base disturbance using the arterial blood gas and basic metabolic panel.

The patient has a primary metabolic acidosis (pH < 7.35 and HCO3- < 24 mEq/L) with a normal anion gap of 10 mEq/L (139 - [114 + 15]).

A normal anion gap metabolic acidosis is highly consistent with her history of severe diarrhea causing gastrointestinal bicarbonate loss.

Determine the expected respiratory compensation using Winter's formula.

Expected PaCO2 = 1.5 × 15 + 8 = 30.5 ± 2 mm Hg (range: 28.5 to 32.5 mm Hg).

Evaluating respiratory compensation is essential to identify mixed acid-base disorders that can mask impending respiratory failure.

Compare the expected PaCO2 with the patient's actual PaCO2 to diagnose any secondary disorder.

The actual PaCO2 is 39 mm Hg, which is significantly higher than the expected maximum of 32.5 mm Hg.

A PaCO2 higher than expected indicates a superimposed primary respiratory acidosis, reflecting respiratory muscle fatigue and a failure to ventilate adequately.

Select the most appropriate clinical intervention for acute-on-chronic hypercapnic respiratory failure.

Initiation of noninvasive positive pressure ventilation (NPPV).

NPPV reduces the work of breathing and improves alveolar ventilation in COPD patients with acute hypercapnic respiratory failure who are somnolent but still able to protect their airway.

Key Concept

Winter's formula (Expected PaCO2 = 1.5 × [HCO3-] + 8 ± 2) is used to assess respiratory compensation in metabolic acidosis; an actual PaCO2 higher than expected indicates a superimposed respiratory acidosis, which in a COPD patient signifies impending respiratory failure requiring ventilatory support.

Estimated Time:2m 0s

PreviousPage 68 / 158Next

Internal Medicine

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Answer

Step-by-Step Solution

Key Concept