Respiration 13 Diseases Of Pleura

Diseases of Pleura

Pleuritis • Pain due to acute pleural inflammation is caused by irritation of the parietal pleura • Pain is localized, sharp, and fleeting • It is made worse by coughing, sneezing, deep breathing, or movement • When the central portion of the diaphragmatic parietal pleura is irritated, pain may be referred to the ipsilateral shoulder

Causes of pleuritis • In young, otherwise healthy individuals, pleuritis is usually caused by viral respiratory infections or pneumonia • The presence of pleural effusion, pleural thickening, or air in the pleural space requires further diagnostic and therapeutic measures • Simple rib fracture may cause severe pleurisy

Treatment of pleuritis: • Treating the underlying disease • Analgesics and anti-inflammatory drugs (eg, indomethacin, 25 mg orally two or three times daily) are often helpful for pain relief • Codeine (30–60 mg orally every 8 hours) may be used to control cough associated with pleuritic chest pain if retention of airway secretions is not a likely complication. • Intercostal nerve blocks are sometimes helpful but the benefit is usually transient

Pleural Effusion • A pleural effusion is an abnormal accumulation of fluid in the pleural space • Five pathophysiologic processes account for most pleural effusions: 1. Increased production of fluid in the setting of normal capillaries due to increased hydrostatic or decreased oncotic pressures (transudates) 2. Increased production of fluid due to abnormal capillary permeability (exudates) 3. Decreased lymphatic clearance of fluid from the pleural space (exudates) 4. Infection in the pleural space (empyema) 5. Bleeding into the pleural space (hemothorax).

Classification Pleural exudate • A pleural exudate is an effusion that has one or more of the following laboratory features: • (1) ratio of pleural fluid protein to serum protein > 0.5 • (2) ratio of pleural fluid LDH to serum LDH > 0.6 • (3) pleural fluid LDH greater than two-thirds the upper limit of normal serum LDH. • Exudates form as a result of pleural disease associated with increased capillary permeability or reduced lymphatic drainage • Bacterial pneumonia and cancer are the most common causes of exudative effusion, but there are many other causes with characteristic laboratory findings

Pleural Transudates Transudates have none of these features • Transudates occur in the setting of normal capillary integrity and suggest the absence of local pleural disease • Glucose equal to serum glucose • pH between 7.40 and 7.55, and fewer than 1000 white blood cells/mcL with a predominance of mononuclear cells • Causes include increased hydrostatic pressure (congestive heart failure accounts for 90% of transudates), decreased oncotic pressure (hypoalbuminemia, cirrhosis), and greater negative pleural pressure (acute atelectasis)

Causes of pleural fluid transudates and exudates

Transudates

• Congestive heart failure ( 90% of cases) • Cirrhosis with ascites • Nephrotic syndrome • Peritoneal dialysis • Myxedema • Acute atelectasis • Constrictive pericarditis • Superior vena cava obstruction • Pulmonary embolism

Exudates • Pneumonia (parapneumonic effusion) • Cancer • Pulmonary embolism • Bacterial infection • Tuberculosis • Connective tissue disease • Viral infection • Fungal infection • Rickettsial infection • Parasitic infection  

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Asbestos  Meigs' syndrome   Pancreatic disease   Uremia  Chronic atelectasis    Chylothorax   Sarcoidosis  Drug reaction Post-myocardial infarction syndrome

Pleural Effusion Essentials of Diagnosis • May be asymptomatic • Chest pain frequently seen in the setting of pleuritis, trauma, or infection • Dyspnea is common with large effusions. • Dullness to percussion and decreased breath sounds over the effusion • Radiographic evidence of pleural effusion • Diagnostic findings on thoracentesis

Diagnostic thoracentesis • Diagnostic thoracentesis should be performed whenever there is a new pleural effusion and no clinically apparent cause • Observation is appropriate in some situations (eg, symmetric bilateral pleural effusions in the setting of congestive heart failure) • Atypical presentation or failure of an effusion to resolve as expected warrants thoracentesis

Clinical Findings • Dyspnea, cough, or respirophasic chest pain • Physical findings are usually absent in small effusions • Larger effusions may present with dullness to percussion and diminished or absent breath sounds over the effusion • Compressive atelectasis may cause bronchial breath sounds and egophony just above the effusion • Massive effusion with increased intrapleural pressure may cause contralateral shift of the trachea and bulging of the intercostal spaces • A pleural friction rub indicates infarction or pleuritis

Laboratory Findings Gross appearance of pleural fluid: • Grossly purulent fluid signifies empyema • Milky white pleural fluid should be centrifuged and clear supernatant above a pellet of white cells indicates empyema, whereas a persistently turbid supernatant suggests a chylous effusion • Hemorrhagic pleural effusion is a mixture of blood and pleural fluid • Hemothorax is the presence of gross blood in the pleural space, usually following chest trauma or instrumentation

Lab tests for pleural fluid • Pleural fluid samples should be sent for measurement of protein, glucose, and LDH in addition to total and differential white blood cell counts • Thoracentesis with culture and pleural biopsy

Characteristics of important exudative pleural effusions

Etiology or Type of Effusion

Gross White Blood Red Blood Cell Glucose Appearance Cell Count Count (cells/mcL) (cells/mcL)

Malignant effusion

Turbid to 1000 to < bloody; 100,000 M occasionall y serous

100 to several hundred thousand

Equal to Eosinophilia serum uncommon; levels; < 60 positive mg/dL in results on 15% of cytologic cases examination

< 5000

Equal to Tube serum levelsthoracostom y unnecessary

Uncomplicate Clear to d turbid parapneumo nic effusion

5000– 25,000 P

Empyema

25,000– < 5000 100,000 P

Turbid to purulent

Comments

Less than Drainage serum necessary; levels; often putrid odor very low suggests anaerobic

Etiology or Type of Effusion

Gross White Blood Red Blood Appearance Cell Count Cell Count (cells/mcL) (cells/mcL)

Tuberculosi Serous to 5000– s serosangui 10,000 M neous

< 10,000

Glucose

Comments

Equal to serum levels; occasionall y < 60 mg/dL

Protein > 4.0 g/dL and may exceed 5 g/dL; eosinophils (> 10%) or mesothelial cells (> 5%) make diagnosis unlikely

Imaging • On a standard upright chest radiograph, approximately 75–100 mL of pleural fluid must accumulate in the posterior costophrenic sulcus to be visible on the lateral view, and 175–200 mL must be present in the lateral costophrenic sulcus to be visible on the frontal view • Chest CT scans may identify as little as 10 mL of fluid • At least 1 cm of fluid on the decubitus view is necessary to permit blind thoracentesis • Ultrasonography is useful to guide thoracentesis in the setting of smaller effusions

Treatment Transudative Pleural Effusion

• Transudative pleural effusions characteristically occur in the absence of pleural disease • Treatment is directed at the underlying condition • Therapeutic thoracentesis for severe dyspnea typically offers only transient benefit

Malignant Pleural Effusion

• Most common causes are lung cancer and breast cancer. • Most patients with malignant effusions have advanced disease and multiple symptoms • Treatment may be systemic, with therapy for the underlying malignancy; or local, to address specific symptoms related to the effusion itself Local treatment usually involves: • Drainage through repeated thoracentesis • Placement of a chest tube • Pleurodesis: It is a procedure by which an irritant is placed into the pleural space following chest tube drainage and lung reexpansion. The goal is to form fibrous adhesions between the visceral and parietal pleura, resulting in obliteration of the pleural space to prevent or significantly reduce reaccumulation of pleural fluid. Multiple agents have been used for pleurodesis, but the two in most common use are doxycycline and sterile, asbestos-free talc

Parapneumonic Pleural Effusion • Parapneumonic pleural effusions are exudates that accompany bacterial pneumonias

• They are divided into three categories: simple or uncomplicated, complicated, and empyema • Uncomplicated parapneumonic effusions do not need drainage • Empyema should always be drained by tube thoracostomy to facilitate clearance of infection and to reduce the probability of fibrous encasement of the lung, causing permanent pulmonary impairment • Complicated parapneumonic effusions present the most difficult management decisions. The clinician should consider drainage of a complicated effusion under different conditions

Hemothorax

• A small-volume hemothorax that is stable or improving on chest radiographs may be managed by close observation • In all other cases, hemothorax is treated by immediate insertion of a large-bore thoracostomy tube to 1. drain existing blood and clot 2. quantify the amount of bleeding 3. reduce the risk of fibrothorax 4. permit apposition of the pleural surfaces in an attempt to reduce hemorrhage • Thoracotomy may be indicated to control hemorrhage, remove clot, and treat complications such as bronchopleural fistula formation.

Spontaneous Pneumothorax • Pneumothorax is accumulation of air in the pleural space • It is classified as spontaneous (primary or secondary) or traumatic • Primary spontaneous pneumothorax occurs in the absence of an underlying lung disease • Secondary spontaneous pneumothorax is a complication of preexisting pulmonary disease • Traumatic pneumothorax results from penetrating or blunt trauma

• Iatrogenic pneumothorax may follow procedures such as thoracentesis, pleural biopsy, subclavian or internal jugular vein catheter placement, percutaneous lung biopsy, bronchoscopy with transbronchial biopsy, and positivepressure mechanical ventilation

• Tension pneumothorax usually occurs in the setting of penetrating trauma, lung infection, cardiopulmonary resuscitation, or positivepressure mechanical ventilation. In tension pneumothorax, the pressure of air in the pleural space exceeds ambient pressure throughout the respiratory cycle. A check-valve mechanism allows air to enter the pleural space on inspiration and prevents egress of air on expiration

Tension Pneumothorax:

Clinical Findings Symptoms and Signs • Chest pain ranging from minimal to severe on the affected side • Dyspnea • Symptoms usually begin during rest and usually resolve within 24 hours even if the pneumothorax persists • Pneumothorax may present with lifethreatening respiratory failure if underlying COPD or asthma is present

• If pneumothorax is small (less than 15% of a hemithorax), physical findings, other than mild tachycardia, are unimpressive • If pneumothorax is large, diminished breath sounds, decreased tactile fremitus, and decreased movement of the chest are often noted • Tension pneumothorax should be suspected in the presence of marked tachycardia, hypotension, and mediastinal or tracheal shift

Imaging • Demonstration of a visceral pleural line on chest radiograph is diagnostic and may only be seen on an expiratory film • A few patients have secondary pleural effusion that demonstrates a characteristic air-fluid level on chest radiography • In supine patients, pneumothorax on a conventional chest radiograph may appear as an abnormally radiolucent costophrenic sulcus (the "deep sulcus" sign) • In patients with tension pneumothorax, chest radiographs show a large amount of air in the affected hemithorax and contralateral shift of the mediastinum

The complete translucency on the left with absence of vascular markings is characteristic of a pneumothorax. What appears as a left hilar mass is in fact the collapsed left lung retracted into a small central density

Note the marked difference in X-ray transparency (density) between the left and right thoracic cavities .The complete radio-translucency (manifest as greater film density or darker lung field on the image) of the thorax with absence of vascular markings is characteristic of a pneumothorax

There is a small pneumothorax present on the radiograph to the left. It is located in the left pulmonary apex. Notice that the left apex is slightly more lucent than the right. In the left third intercostal space, there is a thin white line (see magnified picture below) that represents the pleural surface of the lung. Increased lucency more peripheral to this line is the air trapped in the pleural space

Apical pneumothorax. •

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A thin line caused by the visceral pleura is seen separated from the lateral chest wall (arrows) Notice that no pulmonary vessels are seen beyond this line and that the line is curved Notice also that the pleural line is white and that it is almost equally dark on the side of the pneumothorax and the side of the lung.

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3 things to look for to confirm the presence of a tension pneumothorax

1.

The visceral-pleura white line. (as marked by the white dots) Loss of pulmonary markings over the left lung. The mediastinum is shifted to the right and the diaphragm over the left side is pushed downwards.

2. 3.

Treatment

• Treatment depends on the severity of pneumothorax and the nature of the underlying disease • In patient with a small (< 15% of a hemithorax), stable spontaneous primary pneumothorax, observation alone may be appropriate • Many small pneumothoraces resolve spontaneously as air is absorbed from the pleural space; supplemental oxygen therapy may increase the rate of reabsorption

• Spontaneous primary pneumothoraces that are large or progressive can have simple aspiration drainage of pleural air with a small-bore catheter (eg, 16 gauge angiocatheter or larger drainage catheter) • Placement of a small-bore chest tube (7F to 14F) attached to a one-way Heimlich valve provides protection against development of tension pneumothorax and may permit observation from home • The patient should be treated symptomatically for cough and chest pain, and followed with serial chest radiographs every 24 hours

• Patients with secondary pneumothorax, large pneumothorax, tension pneumothorax, or severe symptoms or those who have a pneumothorax on mechanical ventilation should undergo chest tube placement (tube thoracostomy) • The chest tube is placed under water-seal drainage, and suction is applied until the lung expands. The chest tube can be removed after the air leak subsides • All patients who smoke should be advised to discontinue smoking and warned that the risk of recurrence is 50% • Future exposure to high altitudes, flying in unpressurized aircraft, and scuba diving should be avoided