Pleural Diseases

Pleural Effusion

Typical Case of Pleural Effusion:

The patient is a 62-year-old white male with a 2-month history of orthopnea, bilateral lower extremity edema, and a non-productive cough. He denies fever, chills, or night sweats. His cardiac history is remarkable for known coronary artery disease. He has had no prior pulmonary infections or tuberculosis exposure; however, his PPD reactivity has never been measured.

Physical exam: vital signs were P 100, BP 110/70, T 37, and RR 24. Pulmonary exam demonstrated decreased breath sounds over the right lower 1/3 of the chest. There was dullness to percussion with decreased fremitus at the right base. Egophony was present in a narrow band immediately above the dullness (due to an area of collapsed lung forming a consolidation) & was associated with an area of bronchial breath sounds. Cardiovascular exam was remarkable for JVD about 8 cm above the sternal notch, regular rhythm with a grade II/VI SEM, and no S3 or S4. Lower extremities had 2+ pitting edema. The rest of the physical exam was unremarkable. 

The pleura is really 2 continuous layers à they are separated by the pleural space which contains about 15mL of fluid – this is there to provide lubrication between the 2 layers during breathing

Accumulation of fluid within the pleural space is known as pleural effusion. This is not a disease itself but rather a manifestation of other diseases.  

Etiology:

·         Systemic factors à transudative

·         Local factors à exudative

Causes of Transudative Pleural Effusions:

·         CHF

·         Cirrhosis

·         Nephritic syndrome

·         Hypoalbuminemia

·         Unusual causes à peritoneal dialysis, urinothorax (ipsilateral obstructive uropathy), & atelectasis 

Causes of Exudative Pleural Effusions:

·         Infection à paraneumonic (bacterial, fungal, Nocardia, Actinomyces)

·         Iatrogenic à esophageal perforation or hemothorax

·         Malignancy à carcinoma, lymphoma, mesothelioma – may cause obstruction to lymphatic drainage)

·         Other inflammatory disorders à pancreatitis, asbestos, uremia, radiation

·         Connective tissue disorders à SLE, RA, mixed CT disease 

Symptoms of Pleural Effusion:

·         Cough

·         Dyspnea

·         Pleuritic chest pain

·         Associated symptoms related to the primary disease process à need to pay attention to if the patient has CHF, liver disease, etc. 

Signs of Pleural Effusion:

·         Splinting à patient may try not to move one side of their chest to avoid pleuritic chest pain

·         Dullness to percussion over the area of fluid

·         Fluid blocks transmission of breath sounds à decrease in tactile fremitus & breath sounds

·         Egophony (present above fluid)

·         Signs of associated diseases 

Laboratory Evaluation of Pleural Effusion:

·         Chest X-ray

·         Skin test for TB (PPD skin test)

·         Thoracentesis (pass a needle into the pleural space & sample the fluid)

·         Pleural biopsy à cope needle (cutting needle), thoracoscope, open biopsy  

Analysis of Pleural Fluid:

·         All samples à check physical appearance, protein, lactic dehydrogenase, WBC, RBC, glucose, culture, & cytology

·         If clinically relevant

o        Amylase à will be increased with esophageal rupture

o        PH

o        Triglyceride level & cholesterol level à will be increased if lymphatics are ruptured 

Distinguishing an Exudative from a Transudative Pleural Effusion:

·         Exudative effusion must meet at least one criterion

o        Ratio of pleural fluid : serum protein > 0.5

o        Ratio of pleural fluid LDH : serum LDH > 0.6

o        Pleural fluid LDH > 2/3 serum LDH (200 international units)

·         Transudative effusion is due to systemic effects à capillaries of the pleura are intact & keep large molecules in the vascular space & out of the pleura (opposite is true for exudative effusions)  
 

Paraneumonic Pleural Effusion:

·         Important to distinguish à empyema (frank pus), complicated (requires drainage), & uncomplicated (resolves without drainage)

·         Complicated requires drainage à positive culture or gram stain, extensive loculations, & > 50% of hemothorax

Algorithm for the Assessment of Pleural Effusion: 

Unilateral Paralysis of the Diaphragm:

·         Causes

o        Trauma à sneezing, motor vehicle accident, post-open heart surgery

o        Lesions adjacent to or involving the phrenic nerve à pneumonia, substernal thyroid, aortic aneurysm, vasculitis (diabetes), neoplasm

·         Symptoms à dyspnea on exertion (variable intensity)

·         Physical examination à dullness to percussion, decreased breath sounds, decreased respiratory excursion on the involved side

·         Diagnostic studies

o        Chest X-ray à elevation of hemidiaphragm (most are picked up this way)

o        Sniff test à paradoxical movement of the diaphragm (fluoroscopy or ultrasound) with sniffing – this is a confirmatory test

o        Other studies à based in the likely diagnoses (ex: bronchoscopy if neoplasm seems to be likely)

·         Prognosis à usually good – gradual return in function over 6 months to 1 year

Bilateral Diaphragmatic Paralysis:

·         Similar to unilateral paralysis however symptoms are worse & diagnosis may be more difficult (asymmetry of unilateral paralysis aids in diagnosis)

o        If both sides of the diaphragm are elevated its harder to determine that it’s abnormal

Mediastinum:

·         Mass à usually picked up on routine chest X-ray

o        Often asymptomatic

o        Usually benign

o        Clues to diagnosis are based on location (anterior, middle, or posterior)

o        Investigation à CT scanning or tissue diagnosis (needle mediastinoscopy)

·         Pneumomediastinum à air secondary to mechanical ventilation (barotrauma) or asthma

·         Acute mediastinitis à due to infection and can be treated with antibiotics & surgical drainage

If a patient has a pleural effusion you need to do a clinical assessment. If the cause is obvious then you simply observe under treatment and it will either resolve or not.

If the pleural effusion does not resolve or the cause is not obvious then you need to do a thoracentesis & consider a pleural biopsy. From here you can determine if it’s transudative or exudative. If it’s transudative you can have heart failure or a low albumin state and you need to treat as indicated. If there were a positive diagnosis of exudative pleural effusion then you would also treat as indicated. If there’s a negative diagnosis of exudative effusion then you need to do a PPD test. If the PPD test comes back positive then you would observe the patient under therapy for TB. If there’s still no resolution then you have to repeat the biopsy, thorascopy, or surgical biopsy if indicated and then you can treat as indicated. If the PPD comes back negative then you go straight to repeating the tests & then treat as indicated.
 

Therapy for Pleural Effusion:

·         Treat underlying disease

·         Repeated thoracenteses for symptomatic relief

·         Chest tube drainage for complicated parapneumonic effusion or empyema

·         Pleurodesis for malignant effusions

Pneumothorax

Pneumothorax is air in the pleural space and can be primary or secondary.

·         Primary à no precipitating event – possibly subpleural blebs

o        More often in smokers

o        Peak age is early 20s

·         Secondary à complication of underlying lung disease (ex: COPD, PCP infection, cystic fibrosis, TB)

Clinical Features:

·         Decreased chest excursion on the affected side

·         Decreased breath sounds

·         Chest X-ray à pleural line

·         Primary à 25 – 50% re-occurrence

·         Secondary à symptoms are more severe

Treatment (Primary & Secondary):

·         Supplemental oxygen à normal rate of reabsorption is 1.25% volume of hemithorax per 24hours – this is increased 6 fold with O₂

·         Greater than 15% of hemithorax à aspirate air, tube thoracostomy, tube thoracostomy with pleurodesis, or video-assisted thorascopy
 

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