Unit 10 Pleural Conditions


Disorders of Lung Inflation

Overview of Disorders of Lung Inflation

  • Air enters through the airways, inflating the lung while negative pressure in the pleural cavity prevents lung collapse.

  • Disorders of lung inflation arise from:

    • Airway obstruction.

    • Lung compression (e.g., fluid accumulation in the intrapleural space).

    • Lung collapse (e.g., atelectasis, pneumothorax).

    • Reference: Brown-Richards, 2024, p. 951.

Disorders of the Pleura

Structure and Function of the Pleura

  • The pleura is a double-layered serous membrane that encases the lungs:

    • Parietal Layer: Lines the thoracic wall and diaphragm, continuing around the heart and forming mediastinal walls.

    • Visceral Layer: Directly covers the lung surfaces.

  • The Pleural Cavity: Contains a thin layer of serous fluid that lubricates the pleural surfaces, allowing smooth movement during breathing.

  • Negative pressure in the pleural cavity prevents lung collapse and facilitates lung inflation.

Disorders of the Pleura

  • Common disorders include:

    • Pleural effusion.

    • Hemothorax.

    • Pneumothorax.

    • Pleural inflammation.

Pleural Effusion

Definition of Pleural Effusion

  • Pleural Effusion: Abnormal collection of fluid in the pleural cavity.

    • Occurs when fluid formation rate exceeds removal rate.

    • Can be unilateral (more common) or bilateral.

Etiology and Pathogenesis of Pleural Effusion

  • Due to the pleura's permeability, fluid can cross into the pleural space.

  • Small effusions may not impair lung function and can be resolved by the lymphatic system once the underlying cause is treated.

  • Significant effusions often stem from conditions causing transudation or exudation from blood or lymphatic vessels beneath the pleura or due to blockages/injuries affecting lymphatic drainage.

Classifications of Pleural Effusion

  • Effusions can be classified as:

    • Transudative: Clear, watery fluid (hydrothorax); often a result of congestive heart failure.

    • Exudative: Contains high concentrations of white blood cells and plasma proteins; related to pneumonia, viral infections, pulmonary infarction, and malignancies (about 70% of pleural effusions).

    • Purulent: Contains pus, e.g., empyema.

    • Chyle: Milky fluid from the gastrointestinal tract; termed chylothorax when lymph fills the thoracic cavity.

    • Sanguineous: Bloody fluid.

Clinical Manifestations and Diagnosis of Pleural Effusion

  • Clinical Manifestations: Vary with etiology:

    • Common symptoms include dyspnea and increased work of breathing due to fluid compressing the lung.

    • Patients may exhibit restlessness, anxiety, and report sharp pain worsening during deep inspiration.

    • Large effusions may lead to continuous discomfort.

    • Pleuritic pain only present when inflammation occurs.

    • Characteristic findings include chest dullness or flatness upon percussion and decreased breath sounds upon auscultation.

    • Hypoxemia may occur when surface area is decreased but is typically corrected with supplemental oxygen. Empyema is marked by fever and elevated WBC.

  • Diagnosis: Confirmed through:

    • Chest X-rays, ultrasonography, and CT scans.

    • Thoracentesis (needle aspiration) to identify effusion type and provide symptomatic relief.

Hemothorax

Definition of Hemothorax

  • Hemothorax: A form of pleural effusion characterized by blood accumulation in the pleural space between the lungs and chest wall.

Etiology and Pathogenesis of Hemothorax

  • Occurs commonly due to:

    • Chest injuries.

    • Complications from surgery.

    • Malignancies.

    • Ruptured great vessels (e.g., aortic aneurysm).

  • Classified by amount as minimal, moderate, or large.

Clinical Manifestations of Hemothorax

  • Sudden onset of clinical features, including:

    • Distress with altered gas exchange, ventilation, and breath sounds.

    • Signs of blood loss (e.g., tachycardia).

  • If untreated, moderate to large hemothorax may lead to fibrothorax, with fusion of pleural surfaces and, in severe cases, calcification.

  • Diagnosis: Utilizes chest radiographs, pulse oximetry, and ABGs to assess O₂ saturation and gas exchange efficacy.

Pneumothorax

Definition and Types of Pneumothorax

  • Pneumothorax: Presence of air in the pleural space leading to partial or complete lung collapse.

    • Types:

    1. Spontaneous Pneumothorax: No clear cause or injury.

    2. Traumatic Pneumothorax: Results from direct injury to the chest or airways.

    3. Tension Pneumothorax: Life-threatening condition due to increased intrapleural pressure (air can enter but not leave) impairing both respiratory and cardiac function.

Etiology and Pathogenesis of Pneumothorax

Spontaneous Pneumothorax

  • Occurs due to rupture of air-filled blebs on the lung surface, allowing atmospheric air into the pleural cavity.

  • Primary pneumothorax: occurs in otherwise heathy individuals

  • Secondary pneumothorax: usually more serious 2° occurrence in individuals with underlying lung dz → trapping of gases and destruction of lung tissue

    oCommon etiology: emphysema

    oAssociated conditions: asthma, tuberculosis, cystic fibrosis, sarcoidosis, bronchogenic carcinoma, and metastatic pleural dz

- Leads to lung collapse due to pressure gradients.

Traumatic Pneumothorax

  • Results from penetrating and non-penetrating injuries, fractures, dislocated ribs, and iatrogenic conditions.

Clinical Manifestations of Pneumothorax

  • Depend on pneumothorax size and lung integrity. Pneumothorax include:

    • Sudden chest pain on the same side (ipsilateral).

    • Increased respiratory rate and dyspnea.

    • Chest asymmetry and hyper-resonance upon percussion; decreased or absent breath sounds over the affected area.

    • Hypoxia→ followed by vasoconstriction of the blood vessels in the affected lung → blood to shift to the unaffected lung

Tension Pneumothorax Observations

  • Structures shift away from the tension pneumothorax side, with potential tracheal deviation.

  • Breath sounds may be absent on the side opposite the shift, indicating critical status.

  • Accompanying signs may include jugular vein distention, subcutaneous emphysema, and clinical signs of shock due to compromised cardiac function.

  • Without immediate intervention, the increase in thoracic pressure can lead to respiratory and cardiac arrest due to severe hypoxemia and hypotension.

Diagnosis of Pneumothorax

  • Diagnosis confirmed via:

    • Chest radiograph or CT scan, suspicious based on clinical presentation.

    • Blood oxygen levels evaluated via pulse oximetry and blood gas analysis.

Pleuritis

Definition of Pleuritis

  • Pleuritis/Pleurisy: Inflammation of the pleura.

    • Commonly associated with infectious diseases involving the pleura and presents with sudden, severe chest pain, typically unilateral.

    • Fear of dying

    • Pain worsens with inspiration→ leading to profound dyspnea, coughing makes it worse

    • High RR, low TV

    • Guarding or splinting chest

  • Important to differentiate pleural pain from:

    • Musculoskeletal strain.

    • Bronchial irritation.

    • Myocardial disease

Atelectasis

Definition of Atelectasis

  • Atelectasis: Incomplete expansion of a lung or portion of a lung.

    • Etiologies include:

    • Airway obstruction.

    • Lung compression (pneumothorax or pleural effusion).

    • Increased recoil of the lung due to loss of pulmonary surfactant.

  • Neonatal Atelectasis: Present at birth (primary; often in premature neonates) or develops soon after (secondary).

    • Conditions leading to neonatal atelectasis include respiratory distress syndrome (RDS), amniotic fluid aspiration, and bronchopulmonary dysplasia.

  • Acquired Atelectasis: Primarily occurs in adults, resulting most commonly from airway obstruction or lung compression, especially post-surgery or with immobility.

    • Preventative measures involve deep breathing, coughing, hydration, and early ambulation to facilitate lung expansion.

Clinical Manifestations and Diagnosis of Atelectasis

  • Clinical Manifestations: Symptoms include:

    • Tachypnea, tachycardia, dyspnea, cyanosis.

    • Signs of hypoxemia may develop, indicating diminished lung function due to collapse.

    • Diagnosis involves clinical observation, radiographic evaluation (chest radiographs), and possibly CT scans for obstruction localization.