Pulmonary and Critical Care Medicine · Pleural Disease · study mode — pick an answer, then reveal.
Question · easy
A diagnostic thoracentesis is performed on a patient with a new pleural effusion. Which of the following pleural fluid results classifies the effusion as exudative by Light's criteria?
Light's criteria define an exudate if at least one of the following is met: pleural fluid/serum protein ratio >0.5, pleural fluid/serum LDH ratio >0.6, or pleural fluid LDH >2/3 the upper limit of normal for serum LDH. A protein ratio of 0.6 exceeds the 0.5 threshold and is therefore exudative. An LDH ratio of 0.5 is below the >0.6 cutoff, and a pleural LDH at one-half the serum upper limit of normal is below the two-thirds threshold, so both would support a transudate. A pleural/serum cholesterol ratio >0.3 (or pleural cholesterol >55 mg/dL) is a useful alternative classifier for ambiguous cases, but it is not part of Light's criteria, and a ratio of 0.2 would not meet it anyway. Combined Light's criteria are highly sensitive (~97%) but only ~85% specific, so about one transudate in four is mislabeled exudative.
MKSAP 19 B.5 Ch.5; Harrison's 22e Ch.305
Question · medium
A 74-year-old man hospitalized with decompensated heart failure has received intravenous furosemide for 5 days. A moderate right pleural effusion is sampled: pleural fluid/serum protein ratio is 0.62 and pleural fluid/serum LDH ratio is 0.7, meeting exudative Light's criteria. He is afebrile without pleuritic chest pain, and the clinical picture is otherwise classic for a heart-failure effusion. Which of the following is the most appropriate next step in interpreting this result?
About 25% of transudates — classically heart-failure effusions after loop-diuretic therapy — meet exudative Light's criteria because diuresis concentrates pleural protein and LDH, creating a 'pseudoexudate.' When the clinical story still fits a transudative process, the serum-to-pleural fluid protein gradient (SPPG) >3.1 g/dL or serum-to-pleural albumin gradient (SPAG) >1.2 g/dL reclassifies the effusion as a transudate (reported sensitivity ~100% in heart failure and ~99% in hepatic hydrothorax); a serum NT-proBNP >1500 pg/mL also strongly supports a cardiac effusion. CT-guided biopsy is unwarranted in a patient with an obvious transudative mechanism and no features suggesting malignancy. Chest-tube drainage is reserved for complicated parapneumonic effusions or empyema (pH <7.20, glucose <60 mg/dL, LDH >1000 U/L, pus, or positive Gram stain), none of which are present here. Withholding diuresis in decompensated heart failure to repeat sampling later is clinically inappropriate.
MKSAP 19 B.5 Ch.5; Harrison's 22e Ch.305
Question · medium
A 58-year-old woman with community-acquired pneumonia has a loculated left pleural effusion. Pleural fluid analysis shows pH 7.12, glucose 38 mg/dL, and LDH 1400 U/L; Gram stain shows no organisms. In addition to empiric antibiotics that cover anaerobes, which of the following is the most appropriate management of the effusion?
This effusion meets multiple thresholds for a complicated parapneumonic effusion requiring drainage: pH <7.20, glucose <60 mg/dL, LDH >1000 U/L, and loculated fluid (gross pus or a positive Gram stain/culture would also mandate drainage). Antibiotics alone cannot sterilize a complicated effusion or empyema, and delayed drainage is the main modifiable driver of treatment failure; untreated fibrinopurulent collections organize into a restrictive peel (trapped lung) requiring decortication. If tube drainage is incomplete, the MIST2 regimen of combined intrapleural tPA 10 mg plus DNase 5 mg twice daily for 3 days improves radiographic clearance and reduces surgical referral — but neither agent alone helped, so tPA monotherapy is incorrect. BTS 2023 also endorses a reduced-dose regimen (tPA 5 mg plus DNase 5 mg) when bleeding risk is high. Immediate open decortication is reserved for failure of catheter-based drainage and thoracoscopic adhesiolysis, not as initial therapy.
MKSAP 19 B.5 Ch.5; BTS 2023 (Thorax 2023;78:1143)
Question · hard
A 66-year-old woman with metastatic breast carcinoma has a recurrent, symptomatic, cytology-confirmed malignant right pleural effusion. Large-volume thoracentesis relieves her dyspnea, but a post-procedure radiograph shows a small asymptomatic apical pneumothorax ex vacuo, and CT demonstrates visceral pleural thickening encasing the lung. Which of the following is the best definitive management strategy for her recurrent effusion?
Pneumothorax ex vacuo after thoracentesis signals a trapped lung — tumor or fibrous peel prevents the lung from re-expanding to appose the chest wall. Chemical pleurodesis requires pleural apposition and will fail in this setting, which makes talc slurry the wrong choice (pleurodesis success of 60–90% depends on the degree of lung re-expansion). An indwelling pleural catheter (IPC) is BTS 2023's first-line option for malignant pleural effusion, provides substantial outpatient symptom relief, works even when the lung is unexpandable, and produces spontaneous pleurodesis in about 50% of patients within 6–8 weeks; the OPTIMUM trial showed a fully ambulatory IPC-first pathway is quality-of-life–equivalent to inpatient talc slurry with fewer hospital days. Observation leaves recurrent dyspnea untreated in a patient whose median survival is only 4–7 months but who clearly benefits from drainage. Surgical decortication is inappropriate in this palliative setting with advanced incurable disease. Of note, pleural fluid cytology sensitivity varies by tumor (~79% for adenocarcinoma, ~6% for mesothelioma), but here the diagnosis is already confirmed.
A 22-year-old tall, thin man who smokes presents with sudden right-sided pleuritic chest pain and breathlessness. He is hemodynamically stable with oxygen saturation 94% on room air; breath sounds are reduced on the right. Chest radiography shows a 3-cm rim between the lung margin and the chest wall at the level of the hilum. Which of the following is the most appropriate initial management?
A rim of more than 2 cm between the lung margin and the chest wall at the level of the hilum defines a large pneumothorax. In a symptomatic patient (breathlessness and chest pain) with a large primary spontaneous pneumothorax, the article's algorithm recommends a small-bore (<14 Fr) thoracostomy tube on high-volume, low-pressure suction. Observation with supplemental oxygen (or simple needle aspiration) is appropriate for a small (<2 cm), minimally symptomatic pneumothorax; the 2024 ERS/EACTS/ESTS guideline conditionally supports conservative management only for minimally symptomatic, clinically stable PSP, and when intervention is needed it favors needle aspiration over chest tube as the initial procedure — but this patient is breathless with a large air collection. Emergent needle decompression is reserved for tension pneumothorax, which is a clinical diagnosis (hypotension, unilateral absent breath sounds, tracheal deviation, distended neck veins) requiring immediate decompression without waiting for imaging; this patient is hemodynamically stable. Recurrence-prevention surgery (pleurodesis with bleb stapling) is indicated after the second ipsilateral PSP or the first secondary spontaneous pneumothorax, not after a first PSP.