A 58-year-old man with a history of hepatitis C-induced liver cirrhosis and chronic obstru… — USMLE Step 2 CK

A $58$ -year-old man with a history of hepatitis C-induced liver cirrhosis and chronic obstructive pulmonary disease (COPD) is brought to the emergency department by his daughter due to increasing confusion and diffuse abdominal pain over the past $24$ hours. His current medications include furosemide, spironolactone, tiotropium, and lactulose. His daughter, who provides a document confirming she is his legally appointed healthcare proxy, insists he receives full medical care. However, the patient's estranged son recently arrived and told the staff, "Dad wouldn't want any of this."

On presentation, his temperature is $38.3^\circ\text{C}$ ( $100.9^\circ\text{F}$ ), blood pressure is $96/60$ mm Hg, pulse is $112$ /min, and respirations are $26$ /min. Pulse oximetry shows $94\%$ on room air. Physical examination reveals scleral icterus and asterixis. Lung auscultation demonstrates decreased breath sounds at the bases but no wheezing. The abdomen is grossly distended, tense, and diffusely tender with shifting dullness.

Arterial blood gas analysis on room air reveals:
- pH: $7.30$
- pCO $_2$ : $30$ mm Hg
- pO $_2$ : $70$ mm Hg
- HCO $_3^-$ : $14$ mEq/L

Serum laboratory studies:
- Creatinine: $1.6$ mg/dL (baseline $0.9$ mg/dL)
- Leukocyte count: $14,000$ /mm $^3$

A diagnostic paracentesis yields cloudy fluid. Fluid analysis shows a leukocyte count of $800$ /mm $^3$ with $80\%$ neutrophils.

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

Intravenous ceftriaxone and albumin administrationAnswer
B
Intravenous piperacillin-tazobactam and metronidazole
C
Endotracheal intubation and mechanical ventilation
D
Administration of systemic corticosteroids and albuterol
E
Defer treatment to convene an ethics committee meeting

Answer

Intravenous ceftriaxone and albumin administration

The correct answer targets the diagnosis of Spontaneous Bacterial Peritonitis (SBP). SBP is diagnosed when the absolute neutrophil count (ANC) in ascitic fluid is

\geq 250

/mm

^3

. This patient's ANC is

640

/mm

^3

(

800 \times 0.80

). The empiric antibiotic of choice is a third-generation cephalosporin, such as intravenous ceftriaxone or cefotaxime, which effectively covers the most common enteric Gram-negative pathogens (e.g., E. coli, Klebsiella). Furthermore, patients with SBP are at high risk for developing hepatorenal syndrome due to splanchnic vasodilation and decreased effective arterial blood volume. Intravenous albumin is strongly indicated to reduce mortality and renal impairment in SBP patients who meet specific criteria: serum creatinine

> 1.0

mg/dL, BUN

> 30

mg/dL, or total bilirubin

> 4.0

mg/dL. This patient's creatinine is

1.6

mg/dL, making albumin administration an essential step.

Step-by-Step Solution

Analyze the ascitic fluid to confirm the diagnosis.

The absolute neutrophil count (ANC) is calculated as

800 \times 0.80 = 640

/mm

^3

. Since this is

>250

/mm

^3

, the diagnosis of Spontaneous Bacterial Peritonitis (SBP) is confirmed.

SBP is defined by an ascitic fluid absolute neutrophil count greater than or equal to

250

/mm

^3

without an obvious intra-abdominal, surgically treatable source.

Evaluate the patient's renal function and criteria for adjunct therapies.

The patient's serum creatinine is

1.6

mg/dL (elevated from

0.9

mg/dL baseline).

Patients with SBP are at high risk for hepatorenal syndrome. Intravenous albumin is indicated if creatinine is

>1.0

mg/dL, BUN is

>30

mg/dL, or total bilirubin is

>4.0

mg/dL.

Select the appropriate pharmacological interventions.

A third-generation cephalosporin (ceftriaxone) and intravenous albumin are selected.

Ceftriaxone provides targeted empiric coverage for the enteric Gram-negative organisms commonly responsible for SBP, while albumin expands intravascular volume and prevents renal failure.

Address the patient's acid-base status and ethical considerations to rule out distractors.

Winter's formula (

1.5 \times 14 + 8 = 29 \pm 2

) perfectly matches the measured pCO

_2

30

mm Hg, meaning no respiratory intervention is needed. Legally, the proxy's decision rules.

Ensures holistic management by recognizing physiological compensation and adhering to legal healthcare directives without delaying urgent care.

Key Concept

Management of Spontaneous Bacterial Peritonitis (SBP) involves targeted antibiotic therapy (third-generation cephalosporins) and intravenous albumin to prevent hepatorenal syndrome in patients meeting specific renal or hepatic criteria.

Estimated Time:1m 30s

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