SIM Lab Flashcards
How do you define a pneumothorax (PTX)?
It is defined by a loss of negative intrapleural pressure resulting in a collapsed lung.
What is the pathophysiology behind most PTX?
Likely due to the rupture of a sub pleural bleb or bullae.
How many patients with PTX have pulmonary bullae?
Bullae are founding >75% of patients with PTX.
How do bullae form?
Due to degradation of elastic fibers in the lung.
What exacerbates digression of elastic fibers in the lung?
Smoking-related inflammation, influx of neutrophils and macrophages.
What does degradation of elastic fibers cause an imbalance in?
Protease-Antiprotenase and oxidant-antioxidant systems.
What happens after bullae have formed?
Small airway obstruction increases alveolar pressure, resulting in air leaking into pulmonary interstitium. This air moves to the hilum where increased pressure causes rupture of mediastinal parietal pleura and resulting PTX formation.
In what populations is PRIMARY spontaneous pneumothorax more common in (no underlying lung disease)?
- More common in males (~2-4:1 male:female)
- Most common in ages 10-30
- More common in tall, thin people
- More common in smokers
- May be familial
What is SECONDARY spontaneous PTX associated with? What ages are most common?
Associated with underlying lung disease, may be life threatening.
-Peak incidence age >55
What lung diseases are associated with secondary spontaneous PTX?
Many underlying conditions, including but not limited to: COPD, cystic fibrosis, alpha-1 antitrypsin deficiency, PCP (pneumocystisis pneumonia), TB, sarcoid, idiopathic pulmonary fibrosis, connective tissue diseases and lung cancer.
When do most cases of PRIMARY spontaneous PTX occur?
AT REST
What do patients usually present with?
Chest pain and/or dyspnea that developed while at rest (cough, palpitations less common)
What might a small PTX present with?
It may be asymptomatic or have minimal symptoms.
What characterizes the pain with PTX?
Classically: sudden onset, sharp, unilateral pleuritic chest pain, with max. intensity at onset that resolves within 24 hours.
What is unique about symptoms in secondary spontaneous pneumothorax?
Symptoms tend to be more severe and do not resolve.
On physical exam, what is the most common finding with PTX?
Tachycardia
What can you see on physical exam with larger PTX?
- Decreased chest wall motion
- Hyperresonnace on percussion
- Diminished fremitus
- Decreased or absent breath sounds on the affected side
What physical exam findings should increase suspicion for tension PTX?
- Tachycardia >135 bpm
- Hypotension
- Cyanosis
What might you see with tension PTX that you don’t see with spontaneous PTX?
Contralateral tracheal deviation and JVD (>4/5 cm).
What are CXR findings for PTX?
- Shows a visceral pleural line outlining the edge of the lung.
- Absence of lung markings beyond the pleural line
What are ultrasound findings for PTX?
Loss of B-lines and loss of sliding pleura.
What is more sensitive:
- Bedside ultrasound
- CXR
Bedside ultrasound
What tests are highly specific for PTX?
Both CXR and US!
What will arterial blood gases (ABG) show in PTX?
- Increased A-a gradient
- Acute respiratory alkalosis
What are the management options for PTX?
- Observation (for small or asymptomatic PTX)
- Aspiration with catheter with immediate removal of catheter
- Insertion of chest tube
- Pleurodesis
- Video-assisted thoracoscopic surgery (VATS)
What is pleurodesis and what is its significance?
Pleurodesis (using talc- makes the lung stick to the chest wall) via chest tube or thorascopy reduces recurrence rate.
When may surgery be indicated?
In primary spontaneous PTX if there is a persistent air leak, e.g. > 4 days or if recurrent PTX
How does oxygen help in PTX?
Oxygen accelerates resorption of air by the pleura.
What type of PTX requires immediate aspiration?
Tension PTX!
What is contraindicated in patients with previous spontaneous PTX (unless bilateral surgical pleurectomy has been performed)?
Deep-sea diving (SCUBA)
