DISORDERS OF THE PLEURA

By Dr Odeyemi A.O. Dept. of Medicine,

College of Health Sciences, Bowen University,

Ogbomoso.

INTRODUCTION

• Disorders of the pleura include;

– Pleural effusion;

– Pneumothorax;

– Mesothelioma

• This lecture focuses on pleural effusion and pneumothorax

PLEURAL EFFUSION

INTRODUCTION

• The pleural space normally contains a very thin layer of fluid.

• A pleural effusion is present when there is an excess quantity of fluid in the pleural space.

PATHOPHYSIOLOGY

• Pleural fluid accumulates when pleural fluid formation exceeds pleural fluid absorption.

• Normally, fluid enters the pleural space from the capillaries in the parietal pleura and is removed via the lymphatics in the parietal pleura.

• Other sources of pleural fluid accumulation includes;

– from the interstitial spaces of the lung via the visceral pleura and;

– From the peritoneal cavity via small holes in the diaphragm.

• Accordingly, a pleural effusion may develop when there is excess pleural fluid formation (from the interstitial spaces of the lung, the parietal pleura, or the peritoneal cavity) or when there is decreased fluid removal by the lymphatics.

CLINICAL FEATURES

• Symptoms are usually that of the underlying clinical condition

• Breathlessness (which may be the only symptom) is common particularly when the fluid is much

• Patients may also be asymptomatic

• Clinical signs include; – Tachypnoea

– Contralateral tracheal deviation (when the volume is large)

– Reduced tactile fremitus and vocal resonance

– Stony dull percussion note

– Decreased or absent breath sounds

INVESTIGATIONS

• The presence of free pleural fluid can be demonstrated with a lateral decubitus chest X-ray, chest CT, or ultrasound.

• Chest X-ray (PA & erect) reveals;

– blunting of the costophrenic angle and;

– homogenous opacity arising from the lung base with the extent depending on the volume

• ≥300mls of fluid is required for it to be detected on a PA chest X-ray

• ≥500mls is required for it to be detected clinically

• Chest ultrasound is now the investigation of choice in the evaluation of pleural effusion.

• Chest CT is indicated when malignancy is suspected

Pleural fluid analysis

• Usually indicated to determine the etiology of the pleural effusion

• Pleural fluid is obtained by thoracocentesis

• Biochemical analysis allows classification into transudate and exudates

• A transudative pleural effusion occurs when systemic factors that influence the formation and absorption of pleural fluid are altered.

• An exudative pleural effusion occurs when local factors that influence the formation and absorption of pleural fluid are altered.

• Transudative and exudative pleural effusions are distinguished using the Light’s criteria.

• Exudative pleural effusions meet at least one of the criteria, whereas transudative pleural effusions meet none

• Light’s criteria – Pleural fluid protein/serum protein >0.5

– Pleural fluid LDH/serum LDH >0.6

– Pleural fluid LDH more than two-thirds the normal upper limit for serum

• The primary reason for making this differentiation is that additional diagnostic procedures are indicated with exudative effusions to define the cause of the local disease.

• In some instances (e.g. left ventricular failure), pleural fluid analysis may not be necessary

• Appropriate treatment of the underlying condition (i.e. left ventricular failure in the above example) usually leads to resolution of the effusion)

• The most common cause of pleural effusion is left ventricular failure

• Leading causes of exudative pleural effusions are bacterial pneumonia, malignancy, viral infection, and pulmonary embolism.

Causes of transudative Pleural Effusions

• Congestive heart failure

• Cirrhosis

• Nephrotic syndrome

• Peritoneal dialysis

• Superior vena cava obstruction

• Myxedema

• Urinothorax

Causes of exudative Pleural Effusions

• Neoplastic diseases – Metastatic disease – Mesothelioma

• Infectious diseases – Bacterial infections – Tuberculosis – Fungal infections – Viral infections – Parasitic infections

• Haemothorax • Drugs e.g. amiodarone

• Pulmonary embolization • Gastrointestinal disease

– Esophageal perforation – Pancreatic disease – Intraabdominal

abscesses – Diaphragmatic hernia – After abdominal surgery – Endoscopic variceal

sclerotherapy – After liver transplant

• And many more

MANAGEMENT OF PARAPNEUMONIC EFFUSION

• If the free fluid separates the lung from the chest wall by >10 mm, a therapeutic thoracentesis should be performed (fig 1).

• Factors indicating the likely need for drainage include the following; – Loculated pleural fluid – Pleural fluid pH <7.20 – Pleural fluid glucose <3.3 mmol/L (<60 mg/dL) – Positive Gram stain or culture of the pleural fluid – Presence of gross pus in the pleural space

Figure 1

Malignant pleural effusion

• Malignant pleural effusions secondary to metastatic disease are the second most common type of exudative pleural effusion.

• The three tumors that cause ~75% of all malignant pleural effusions are lung carcinoma, breast carcinoma, and lymphoma

• Diagnosis usually is made via cytology of the pleural fluid.

• If the patient has a disabling dyspnoea that is relieved with a therapeutic thoracocentesis, one of the following procedures should be considered;

– insertion of a small indwelling catheter or;

– tube thoracostomy with pleurodesis (i.e. instillation of a sclerosing agent such as doxycycline or bleomycin).

PNEUMOTHORAX

INTRODUCTION

• Pneumothorax is the presence of air in the pleural space. It is classified as;

• Spontaneous pneumothorax: Develops without preceding trauma or other obvious cause.

• Traumatic pneumothorax: Develops as a result of trauma to the chest, including diagnostic or therapeutic maneuvers (i.e. iatrogenic)

Spontaneous pneumothorax

• Spontaneous pneumothoraxes are subclassified as primary or secondary.

• A primary spontaneous pneumothorax presents in an otherwise healthy person without underlying lung disease.

• A secondary spontaneous pneumothorax complicates an underlying lung disease, most commonly chronic obstructive pulmonary disease (COPD).

Primary spontaneous pneumothorax

• Usually due to rupture of apical pleural blebs (small cystic spaces that lie within or immediately under the visceral pleura).

• It occurs almost exclusively in smokers.

• It is common in young, tall and thin males

• Recurrence of (PSP) is common (~50%)

Secondary pneumothorax

• Most are usually due to chronic obstructive pulmonary disease

• Pneumothoraxes have however been reported with virtually every lung disease.

• Pneumothorax in patients with lung disease is more life-threatening than it is in normal individuals because of the lack of pulmonary reserve in these patients

Types of Spontaneous Pneumothorax

• Closed

• Open

• Valvular (tension)

Closed spontaneous pneumothorax

• The communication between the lung and pleural space seals off as the lung deflates and does not reopen.

• The mean pleural pressure remains negative.

• Air in the pleural space gets reabsorbed spontaneously, the underlying lung re-expands over a few days or weeks.

• Infection is rare

Closed spontaneous pneumothorax

Open pneumothorax

• The communication between the lung and pleural space fails to seal

• Air continues to move freely between the lung and pleural space.

• Usually develops following rupture of a tuberculosis cavity, an emphysematous bulla or lung abscess into the pleural space.

Open pneumothorax (2)

• The mean pleural pressure remains equal to atmospheric pressure; lung cannot expand.

• Bronchopleural fistula, spread of infection from the airways into the pleural space resulting in empyema are common.

Open spontaneous pneumothorax

Tension pneumothorax

• The communication between the airway and the pleura acts as a one-way valve allowing air to enter the pleural space during inspiration but not to escape on expiration.

• This results in large amounts of air being trapped in the pleural space

• The intrapleural pressure may become more than the atmospheric pressure.

Tension pneumothorax (2)

• This may cause mediastinal shift towards the opposite side, compression of the opposite normal lung, impairment of systemic venous return and may result in cardiovascular compromise.

• It usually occurs during mechanical ventilation or resuscitative efforts.

Tension pneumothorax

Traumatic pneumothorax

• It can result from both penetrating and nonpenetrating chest trauma.

• Iatrogenic pneumothorax is a type of traumatic pneumothorax that is becoming more common.

• The leading causes of iatrogenic pneumothorax are transthoracic needle aspiration, thoracentesis, and the insertion of central intravenous catheters

CLINICAL FEATURES

• The most common symptoms are sudden-onset unilateral pleuritic chest pain or breathlessness.

• Breathlessness may be mild and resolve spontaneously or it may be severe (especially in patients with underlying chest disease) and fail to resolve spontaneously.

• In patients with a small pneumothorax, physical examination may be normal.

CLINICAL FEATURES (2)

• Decreased or absent breath sounds may be seen in patients with a large pneumothorax (> 15% of the hemithorax)

• The combination of absent breath sounds and hyperresonant percussion note is diagnostic of pneumothorax.

• Tension pneumothorax manifests with rapidly progressive breathlessness associated with the following;

CLINICAL FEATURES (3)

– marked tachycardia,

– hypotension,

– cyanosis and;

– tracheal displacement away from the side of the silent hemithorax.

• Occasionally, mediastinal shift may be absent in tension pneumothorax, if malignant disease or scarring has splinted the mediastinum.

INVESTIGATIONS

• Chest X-ray shows the sharply defined edge of the deflated lung with no lung markings between this and the chest wall

• X-rays may also show the extent of any mediastinal displacement and reveal any pleural fluid or underlying pulmonary disease

• Chest CT scan may be necessary in difficult cases.

INVESTIGATIONS 2

Right pneumothorax

TREATMENT

• Primary spontaneous pneumothorax (PSP)

• If the lung edge is <2 cm from the chest wall and the patient is not breathless, resolution occurs spontaneouly without intervention

• Moderate or large PSP requires simple aspiration.

• Thoracoscopy with stapling of blebs and pleural abrasion is indicated if; – the lung does not expand with aspiration or;

– if the patient has a recurrent pneumothorax.

TREATMENT (2)

• Secondary Pneumothorax

• Almost all patients with this condition should be treated with tube thoracostomy.

• Most should also be treated with thoracoscopy or thoracotomy with the stapling of blebs and pleural abrasion.

• If surgery is not feasible, pleurodesis should be attempted by the intrapleural injection of a sclerosing agent such as doxycycline.

TREATMENT (3)

• Traumatic Pneumothorax • Treatment is with tube thoracostomy unless they

are very small. • If a haemopneumothorax is present, one chest

tube should be placed in the superior part of the hemithorax to evacuate the air and another should be placed in the inferior part of the hemithorax to remove the blood.

• Iatrogenic pneumothorax is treated with supplemental oxygen or aspiration, (or tube thoracostomy if these fails).

TREATMENT (4)

• Tension pneumothorax

• It must be treated as a medical emergency.

• Death can arise from inadequate cardiac output or marked hypoxemia if the tension in the pleural space is not relieved urgently.

• A large-bore needle should be inserted into the pleural space through the second anterior intercostal space.

TREATMENT (5)

• If large amounts of air escape from the needle after insertion, the diagnosis is confirmed.

• The needle should be left in place until a thoracostomy tube can be inserted.

TREATMENT (6)

• In general, Patients with a closed pneumothorax should be advised not to fly, as the trapped gas expands at altitude

• Diving is potentially dangerous after pneumothorax, unless a surgical pleurodesis has sealed the lung to the chest wall.

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