Pneumothorax
Definition And Epidemiology
- Accumulation extrapulmonary air within chest cavity between parietal, visceral pleura.
- Incidence: 4/100,000 boys, 1/100,000 girls.
Etiology And Classification
Spontaneous Pneumothorax
| Classification | Characteristics And Associations |
|---|---|
| Primary Spontaneous (PSP) | β’ Lacks underlying lung disease. β’ Typically tall, thin adolescent boys. β’ Associated smoking (tobacco, marijuana, crack cocaine, e-cigarettes), MDMA, Valsalva maneuver, apical blebs (controversial). |
| Secondary Spontaneous (SSP) | β’ Underlying lung disease present. β’ Congenital: Congenital Pulmonary Airway Malformation (CPAM), Congenital Lobar Emphysema (CLE), bronchogenic cysts, Birt-Hogg-Dube syndrome. β’ Increased Intrathoracic Pressure: Asthma, bronchiolitis, Cystic Fibrosis (CF), foreign body. β’ Infections: Tuberculosis, Pneumocystis jirovecii, pneumatocele, lung abscess, COVID-19. β’ Lung Diseases: Langerhans cell histiocytosis, Marfan syndrome, Ehlers-Danlos syndrome, pulmonary fibrosis, metastatic osteosarcoma. |
Traumatic And Neonatal Pneumothorax
| Category | Causes |
|---|---|
| Traumatic | β’ Noniatrogenic: Blunt, penetrating trauma. β’ Iatrogenic: Thoracotomy, thoracentesis, tracheostomy, mechanical ventilation, high-flow therapy, tube/needle puncture. |
| Neonatal | Respiratory Distress Syndrome (RDS), meconium aspiration, mechanical ventilation. Oligohydramnios (renal agenesis, obstructive uropathy) leading pulmonary hypoplasia. |
Contributory Factors
- Apical blebs/bullae.
- Pleural porosity (disturbed mesothelial cells).
- Folliculin gene mutations.
Pathophysiology
Mechanism Of Air Leak
- Normal resting state balances outward chest wall expansion against inward lung elastic recoil, generating negative intrapleural pressure.
- Air entering pleural space collapses lung.
- Alveolar hypoventilation, ventilation-perfusion mismatch, intrapulmonary shunt induce hypoxemia.
- Simple pneumothorax: Atmospheric intrapleural pressure, lung collapses up 30%.
Tension Pneumothorax
- Continuous air leak creates increasing positive intrapleural pressure.
- Compresses lung, shifts mediastinal structures contralaterally.
- Decreases venous return, cardiac output, precipitating hemodynamic instability, shock.
- Frequent Secondary Spontaneous Pneumothorax, Traumatic Pneumothorax; uncommon Primary Spontaneous Pneumothorax.
Clinical Manifestations
Symptoms
- Abrupt onset.
- Sharp chest pain, pleuritic nature, worsening during inspiration, cough.
- Dyspnea, cyanosis, breathlessness.
- Potentially minimal/absent depending collapse extent.
Physical Signs
- Tachypnea.
- Affected hemithorax: Decreased chest expansion, hyper-resonance percussion, diminished/absent breath sounds.
- Larynx, trachea, heart shifted toward unaffected side.
- Fluid presence: Gurgling sounds synchronous respirations.
- Tension Pneumothorax specific: Cyanosis, sweating, severe tachypnea, tachycardia, shock.
Evaluation And Diagnosis
Imaging Modalities
| Modality | Diagnostic Findings |
|---|---|
| Chest Radiograph (Upright) | β’ First-line investigation. β’ Black radiolucent rim between visceral pleura, chest wall. Absent bronchovascular markings. β’ Expiratory views accentuate contrast. |
| Chest Ultrasound | β’ Replacing Chest X-Ray β’ Pediatric Intensive Care Unit (PICU) point-of-care tool. β’ Excludes Pneumothorax: Lung sliding, lung pulse, B lines. β’ Confirms Pneumothorax: Absent lung slide, presence lung point, barcode/stratosphere sign. |
| Computed Tomography (CT) | β’ Not routinely recommended initial diagnosis. β’ Identifies underlying disease (apical blebs), evaluates contralateral normal lung recurrences. |
| Transillumination | β’ Useful infants <6 months using fiberoptic light probe. β’ Unreliable older patients, subcutaneous emphysema, atelectasis. |
Sizing Criteria
- Large Pneumothorax (British Thoracic Society): >=2 cm lung margin chest wall hilum level.
- Large Pneumothorax (American College Chest Physicians): >=3 cm apex-to-cupola distance.
Differential Diagnosis
- Localized/generalized emphysema, large emphysematous blebs.
- Large pulmonary cavities, cystic formations.
- Diaphragmatic hernia (evaluate via Barium swallow).
- Compensatory overexpansion concurrent contralateral atelectasis.
- Gaseous gastric distention.
Management
Stepwise Interventions
- Goal encompasses air removal, recurrence prevention.
Observation And Oxygenation
- Indicated small Pneumothorax (<2 cm), lacking respiratory distress.
- High-flow oxygen (10-100%) decreases nitrogen partial pressure, hastens lung reexpansion.
- Avoid observation very young children, traumatic Pneumothorax.
Needle Aspiration
- Indicated large Pneumothorax (>2 cm), respiratory distress, Tension Pneumothorax.
- Execute utilizing large bore intravenous catheter, 3-way stopcock.
- Tension Pneumothorax requires emergent needle decompression prior radiographic confirmation.
Tube Thoracostomy
- Indicated failed simple aspiration, recurrence <7 days, underlying lung disease.
- Site: Midclavicular line, second intercostal space.
- Size: 10 F pigtail catheter minimizes pain, scarring.
- Suction: -20 cmH2O required solely failure inflate >24 hours.
- Removal criteria: Complete reinflation 24 hours, absent bubbling.
Pleurodesis
- Obliterates pleural space adhering parietal, visceral pleura.
- Indications: First occurrence Secondary Spontaneous Pneumothorax, second recurrence Primary Spontaneous Pneumothorax, bilateral spontaneous Pneumothorax, persistent air leak >5-7 days.
- Surgical: Video-Assisted Thoracoscopic Surgery (VATS) or open thoracotomy utilizing mechanical abrasion.
- Chemical: Talc, doxycycline, povidone-iodine, autologous blood patch. Painful, 25% recurrence rate.
Complications And Follow-Up
Complications
- Reexpansion Pulmonary Edema: Suspect developing new-onset cough, breathlessness, chest tightness post-drain insertion. Treat utilizing Positive End-Expiratory Pressure (PEEP).
Follow-Up Guidelines
- Air Travel: Delay flying 7 days to 6 weeks post-resolution. Risk ipsilateral, contralateral recurrence.
- Scuba Diving: Absolutely contraindicated lifelong post-Pneumothorax children.