A 54-year-old man presents to the emergency department with a 5-day history of high fever,… — USMLE Step 2 CK

A $54$ -year-old man presents to the emergency department with a $5$ -day history of high fever, productive cough with rust-colored sputum, and sharp right-sided chest pain that worsens with deep inspiration. He has no significant past medical history other than a $20$ -pack-year smoking history.

His temperature is $38.9^\circ\text{C}$ ( $102.0^\circ\text{F}$ ), blood pressure is $122/78\text{ mm Hg}$ , pulse is $110/\text{min}$ , and respiratory rate is $24/\text{min}$ . Pulse oximetry shows $92\%$ on room air.

Physical examination reveals dullness to percussion and decreased breath sounds over the right lower lung field. A chest radiograph demonstrates a right lower lobe consolidation with a moderate-sized, free-flowing right-sided pleural effusion.

A diagnostic thoracentesis is performed, and pleural fluid analysis yields the following results:

Test	Result
Appearance	Turbid
$\text{pH}$	$7.12$
Glucose	$28\text{ mg/dL}$
Protein	$4.5\text{ g/dL}$ (Serum: $6.0\text{ g/dL}$ )
Lactate dehydrogenase (LDH)	$1200\text{ U/L}$ (Serum: $200\text{ U/L}$ )
Gram stain	Gram-positive diplococci

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

Chest tube placement and targeted intravenous antibioticsCevap
B
Intravenous piperacillin-tazobactam and daily chest radiographs
C
Intravenous furosemide and noninvasive positive pressure ventilation
D
Intravenous sodium bicarbonate infusion and repeat thoracentesis
E
Systemic corticosteroids and inhaled bronchodilators

Cevap

The correct management is chest tube placement and targeted intravenous antibiotics.

The correct answer identifies that this patient has a complicated parapneumonic effusion. A parapneumonic effusion is considered 'complicated' (meaning it is highly unlikely to resolve with antibiotics alone) if it meets any of the following criteria:

\text{pH} < 7.20

, glucose

< 60\text{ mg/dL}

, or direct evidence of microbes (positive Gram stain or culture). This patient meets all three criteria. The standard of care for a complicated parapneumonic effusion or frank empyema is prompt chest tube placement for drainage (source control) combined with targeted intravenous antibiotics based on the Gram stain.

Adım Adım Çözüm

Evaluate the pleural fluid using Light's criteria to determine if it is an exudate or transudate.

The pleural fluid-to-serum protein ratio is

4.5/6.0 = 0.75

(

> 0.5

) and the LDH ratio is

1200/200 = 6.0

(

> 0.6

). The fluid is highly exudative.

Differentiating exudate from transudate narrows the differential diagnosis; exudates typically result from local pleural inflammation or infection.

Assess the specific biochemical and microbiological characteristics of the exudative fluid.

The fluid has a

\text{pH}

7.12

, glucose of

28\text{ mg/dL}

, and a positive Gram stain showing Gram-positive diplococci.

These findings specifically define a complicated parapneumonic effusion (or empyema), which behaves like an abscess in the pleural space.

Determine the appropriate therapeutic intervention for a complicated parapneumonic effusion.

The patient requires immediate pleural space drainage (chest tube thoracostomy) along with pathogen-directed antibiotics.

Antibiotics alone cannot adequately penetrate and clear a highly inflamed, acidic, and loculated pleural space infection; mechanical drainage is mandatory for source control.

Anahtar Kavram

Patients with pneumonia who develop a pleural effusion with a

\text{pH} < 7.20

, glucose

< 60\text{ mg/dL}

, or positive Gram stain/culture have a complicated parapneumonic effusion (empyema) requiring immediate chest tube drainage and antibiotics.

Tahmini Süre:1m 15s

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

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