An Elderly Man With New Lethargy and Abnormal Chest Radiography Findings
Answer: C, place a 14F chest tube with or without tPA-DNase.
This case serves as a springboard for a discussion of the diagnosis and management of the ancient entity of pleural effusion. Medical students and residents everywhere are still taught the classical chest examination findings of diminished breath sounds and dullness to percussion indicative of a fluid collection in the pleural space. Jumping to modern times, the advent of point-of-care ultrasonography has taken the guesswork out of fluid-amount estimates and the detection of septation (important in therapeutic maneuvers, as discussed below) and most importantly, has led to safer thoracentesis for diagnosis and therapy.1 In fact, thoracentesis for fluid analysis and culture is the initial step indicated, as was done in this patient’s case.
Once fluid has been obtained, another timeworn but still appropriate strategy is to differentiate transudate (noninflammatory, hydrostatic/oncotic pressure-related) effusions from inflammatory exudative ones. The Light criteria remain the standard for doing so and define an exudative effusion with at least one of the following findings: (1) the ratio of pleural fluid protein to serum protein exceeds 0.5; (2) the pleural fluid LDH level exceeds 0.67 of the top-normal serum LDH level; or (3) the ratio of pleural fluid to serum LDH exceeds 0.6.2 The presented patient fulfilled all 3 of the Light criteria and thus has an exudative pleural effusion.
The differential diagnosis of pleural effusion is extremely broad, with many unusual “zebras” finding their way into clinicopathologic conferences. If one plays the probabilities, then the overwhelming majority will be one of five or so underlying causes. Among the transudates (which is not the case in our patient), the fluid-retaining states of CHF, cirrhosis, and nephrotic syndrome dominate. All will usually manifest with many other signs and symptoms of the underlying entity (eg, exertional dyspnea, significant edema, stigmata of liver failure). Answer A offers CHF as a potential cause, but although mild edema was present, other CHF findings were absent. The patient’s left-sided effusion rather than the usual right-sided (if unilateral) effusion in CHF makes it a very unlikely cause here.
This brings us to the differential for an exudative pleural effusion, usually either infectious or neoplastic.2 Our patient presented with the typical “failure to thrive” pneumonia (confirmed on imaging) seen in debilitated geriatric populations, and he had a fever and leukocytosis. These findings are adequate to diagnose community-acquired pneumonia with parapneumonic effusion, the most common exudative effusion. The complication of parapneumonic effusion is a significant risk factor for prolongation of hospital stay and poor outcome. A scoring system has been developed assigning risk points for parapneumonic pleural infection, and in high-risk situations, a mortality rate as high as 30% has been reported at 12 weeks.3
Therefore, maneuvers and strategies to better and more quickly treat pleural infection have been analyzed. Varying methods of most effectively removing the fluid, which is vital to cure, are offered in Answers B and D. Serial removal by repeated thoracentesis (Answer D) is not easy, despite point-of-care ultrasonography guidance, due to the viscosity of the fluid precluding effective aspiration with a small-bore needle, and even more so due to loculation of the effusions not allowing free flow. In our patient, the septa and loculations were demonstrated by ultrasonography, and their presence bode poor results of thoracentesis alone,2 making Answer D an incorrect choice.
At the other extreme is proceeding with the most effective but also most aggressive technique of pleural VATS (Answer B). VATS has revolutionized thoracotomy by rendering it far safer than the traditional surgical approach. It has emerged as the definitive treatment for frank empyema (which our patient did not have). However, it is still a relatively high-risk procedure for patients with poor surgical risk such as ours.
Although an argument can be made for the VATS approach, an intermediate strategy is available—the use of small-bore chest tubes (in contrast to older full-size chest tubes), for continual pleural drainage, with the optimal size seeming to be 14F pigtail catheters.4 Positive outcomes regarding endpoints of less pain, avoidance of thoracotomy, and subsequent lower mortality have resulted in guidelines into which our patient seems to fit,2,5 making Answer C the optimal choice.
Another additive maneuver being evaluated with initial positive results is making catheter drainage even more efficient with the administration of intrapleural tPA-DNase to enzymatically dissolve the cellular and proteinaceous debris within the exudate, rendering it less viscous and more amenable to drainage.5 An interesting historical note: This maneuver was first tried with some success 70 years ago by my great mentor, Sol Sherry, MD, after he had discovered the presence of the fibrinolytic system in human plasma, and is so prevalent and effective now in treating causes of acute myocardial infarction, stroke, and pulmonary embolism.6 What a wonderful admixture of the old, the classic, and the modern!