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Toronto Notes 2019 Diseases of the Mediastinum and Pleura Pneumothorax
Definition
• presenceofairinthepleuralspace
Pathophysiology
• entryofairintopleuralspaceraisesintrapleuralpressurecausingpartiallungdeflation
Etiology
• traumatic:penetratingornon-penetratingchestinjuries
• iatrogenic(centralvenouscatheter,thoracentesis,mechanicalventilationwithbarotrauma) • spontaneous(nohistoryoftrauma)
■ primary (no underlying lung disease)
◆ spontaneous rupture of apical subpleural bleb (packets of air) of lung into pleural space ◆ smoker, male, family history, Marfan's syndrome
■ secondary (underlying lung disease)
◆ rupture of subpleural bleb which migrates along bronchioalveolar sheath to the mediastinum
then to the intrapleural space
◆ necrosis of lung tissue adjacent to pleural surface
◆ pneumonia, abscess, PCP, lung CA, COPD, CF, TB, LAM, Pulmonary Langerhans cell
histiocytosis (PLCH)
Signs and Symptoms
• canbeasymptomatic
• acute-onsetpleuriticchestpain,dyspnea
• tachypnea, tachycardia
• trachealdeviation(contralateraldeviationintensionpneumothorax) • ipsilateraldiminishedchestexpansion
• decreasedtactile/vocalfremitus
• hyperresonance
• ipsilateraldiminishedbreathsounds
Investigations
• CXR
■ small:separationofvisceralandparietalpleuraseenasfinecrescenticlineparalleltochestwallatapex ■ large: decreased density and decreased volume of lung on side of pneumothorax
■ see Medical Imaging, MI9
Treatment
• primaryspontaneouspneumothorax
■ stable, small (<3 cm), minimal symptoms: observation + O2
■ symptomatic or large (>3 cm): aspiration
■ unstable/tension pneumothorax: needle decompression then chest tube, and VATS if unsuccessful
(25-50%)
• secondaryspontaneouspneumothorax
■ stable, small (<3 cm), minimal symptoms: observation + O2
■ symptomatic, large, or unstable: chest tube, and VATS if unsuccessful
Asbestos-Related Pleural Disease and Mesothelioma
Etiology and Pathophysiology
• benignmanifestationsofasbestosexposure: ■ benign asbestos pleural effusion
◆ exudative effusion, typically ~10 yr after exposure, resolves ■ pleural plaques, usually calcified
◆ marker of exposure; usually an asymptomatic radiologic finding • mesothelioma
■ primary malignancy of the pleura
■ decades after asbestos exposure (even with limited exposure)
■ smoking not a risk factor, but asbestos and smoking synergistically increase risk of lung cancer
Signs and Symptoms
• persistentchestpain,dyspnea,cough,bloodypleuraleffusion,weightloss
Investigations
• biopsy(pleuroscopicoropen)
• needlebiopsymayseedneedletractwithtumour
Treatment
• resection(extrapleuralpneumonectomy)requirescarefulpatientselection;rarelysuccessful(average survival <1 yr)
Respirology R25
Need to Rule Out Life-Threatening Tension Pneumothorax
If pneumothorax with:
• Severe respiratory distress
• Tracheal deviation to contralateral side • Distended neck veins (JVP)
• Hypotension
Do not perform CXR
Needs immediate treatment See Emergency Medicine, ER11