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Barotrauma
- Extra alveolar gas
- Occurs when gas under pressure causes alveolar rupture
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Predisposing factors for barotraumas!
- High peak airway pressure with low end expiratory pressure
- Bullous lung disease such as may occur with emphysema or history of tuberculosis
- High levels of PEEP, with high tidal volumes
- Aspiration of gastric acid
- Necrotizing pneumonias
- ALI/ARDS
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Subcutaneous Emphysema
- The skin feel crepitant to touch
- It may be visible as puffing of the skin in the patients neck, face, or chest
- Usually occurs without complication and tends to clear without treatment as mean airways are reduced
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Pneumomediastinum
- Can lead to compression of the esophagus, great vessels, and the heart.
- It is easily identified on chest radiograph
- Treatment depends on the severity of the problem and its effect on adjacent structures
- Can cause cardiac tamponade
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Pneumothrax
- Can be detected by a resonant or hyperresonant percussion note and absence of breath sounds on the affected side, and chest radiograph will indicate lack of vascular markings on the affected side
- Treatment usually requries thoracotomy and placement of a chest tube
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Atelectrauma
- Used to describe the injuries to the lungs that occur because of repeated opening and closing of lung units at lower lung volumes
- Inadequate levls of PEEP are applied
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Shear stress
- Occurs when an alveolus that is normally expanded is adjacent to one that is collapsed
- Add PEEP
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Role of PEEP in lung protection!
- Helps restore FRC by recruiting previously collapsed alveoli
- Adequate levels of PEEP prevent repeated collapse and reopening of alveoli and help maintain lung recruitment
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Auto PEEP
Unintentional PEEP that occurs during mechanical ventilation
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The following factors increase the risk of auto PEEP!
- Chronic obstructive airway disease
- High minute ventilation (more than 10-20 L/min) in ventilated patients
- Age greater than 60
- Increased airway resitance
- Increased lung compliance
- High respiratory frequency
- Low inspiratory flow
- Increased Vt
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