Pneumothorax, Respiratory Failure Type 1 and 2 Flashcards
What anatomical structures does pneumothorax affect?
Anatomical space between lungs and chest wall (pleural cavity). Boundaries are visceral (lung) and parietal (chest wall) pleura
What is purpose of serous fluid in pleural cavity?
Allows lubrication of lung against chest wall, preventing friction
Why does pleural cavity contain a vacuum?
Negative pressure to assist process of inspiration / lung expansion
What is pneumothorax?
Collection of air in the pleural cavity (between lungs and chest wall). Causes collapse of lung.
What are effects of pneumothorax?
Impaired mechanics of ventilation / movement of air in and out of lungs
Reduction of O2 if severe
What is primary/secondary pneumothorax?
1ary –> without prior known lung disease
2ary –> COPD or physical trauma to chest (including iatrogenic e.g. surgery)
What are severity of symptoms of pneumothorax determined by?
Size of air leak and speed by which it occurs
What are symptoms/clinical sings of pneumothorax?
- Chest pain
- Shortness of breath
- Deviated trachea (away from side of tension pneumothorax)
- Stethoscope reduced breath sounds (same side)
- Hypoxia
- Hypotension
What is tension pneumothorax?
Air is trapped in the pleural cavity under positive pressure, displacing mediastinal structures and compromising cardiopulmonary function
i.e. tension pneumothorax begins to affect other nearby organs
What would chest x-ray show in pneumothorax?
Air between lung and chest wall at apex of lung
How can small pneumothoraces be treated?
Often resolve by themselves and require no treatment
How can larger pneumothoraces be resolved?
The air may be aspirated with a syringe, or a one-way chest tube / drain is inserted to allow the air to escape
What is 1ary/2ary treatment of pneumothorax?
- Pleurodesis (sticking the lung to the chest wall), may be used if there is a significant risk of repeated episodes of pneumothorax
- Avoid significant changes in atmospheric pressure (e.g. aeroplanes)
What is type 1 respiratory failure?
Low level of O2 in the blood (hypoxemia) with either a normal (normocapnia) or low (hypocapnia) level of CO2 but not an increased level (hypercapnia)
What are the normal partial pressure reference values for CO2 and O2?
PaO2: 10.0 - 13.3 kPa
PaCO2: 4.7 - 6.0 kPa
What structural abnormalities indicate type 1 respiratory failure?
- Significant obstruction of upper airway/trachea/bronchial tree/alveoli
- Fluid, blood or air in pleural space
- Weakness or damage to chest wall / diaphragm
- Damage to brain and central respiratory control by trauma or sedation by drugs
What physical abnormalities are present in type 1 respiratory failure?
- Absence of hypercapnia (high PaCO2)
- Inadequate gas exchange by respiratory system
- Arterial O2 levels cannot be maintained within normal range
- Drop in blood oxygenation (hypoxaemia)
What is type 1 respiratory failure typically caused by?
Ventilation/perfusion (V/Q) mismatch –> volume of air flowing in and out of lungs not matched with flow of blood to lungs
What can cause (V/Q) mismatch causing type 1 respiratory failure?
- Pulmonary embolus blocking pulmonary artery
- Pneumonia resulting in poor gas transfer to and from blood
Symptoms of type 1 respiratory failure?
- Dyspnoea (short of breath)
Clinical signs of respiratory failure?
- Hypoxia (low O2 saturation)
- Tachypnoea (fast respiration)
What are test results in respiratory failure?
- PaO2 markedly decreased (< 8.0 kPa)
- PaCO2 normal or low (< 6.0 kPa)
- pH normal or increased
Treatment for respiratory failure?
- Oxygen
- Treat underlying cause
1ary / 2ary prevention for respiratory failure?
Prevent causes:
- Pulmonary oedema (avoid excess intravenous fluids, use of diuretic therapy)
- Pulmonary embolus (preventative use anticoagulants if a patient is restricted to bed in hospital)
What is type 2 respiratory failure?
Inadequate alveolar ventilation (both O2 and CO2 are affected). Buildup of carbon dioxide levels (PaCO2) that has been generated by the body but cannot be eliminated
What are structural abnormalities of type 2 respiratory failure?
- Any significant obstruction of the upper airway / trachea / bronchial tree / alveoli
- Fluid, blood or air in the pleural space
- Weakness of damage to the chest wall / diaphragm
- Damage to brain and central respiratory control by trauma or sedation by drugs
Physiological abnormalities in type 2 respiratory failure?
Inadequate ventilation of respiratory system so arterial oxygen and/or carbon dioxide levels cannot be maintained within their normal ranges
- Hypercapnia (high PaCO2)
- Hypoxaemia (drop in blood oxygenation)
Causes of type 2 respiratory failure?
- Reduced breathing effort (in fatigued patient)
- A decrease in area of lung available for gas exchange (e.g. in COPD with emphysema)
Symptoms of type 2 respiratory failure?
- Dyspnoea (short of breath)
Clinical signs of type 2 respiratory failure?
- Hypoxia (low O2 saturation)
- Tachypnoea (fast respiration) or low rate of respiration (if drug sedation or brain injury)
What are test results for type 2 respiratory failure?
- PaO2 decreased (< 10.0 kPa)
- PaCO2 increased (> 6.0 kPa)
- pH decreased (respiratory acidosis)
Medical treatment for type 2 respiratory failure?
• Identify and treat underlying cause
• Low flow oxygen (high flow may reduce the respiratory drive of the
brain and cause reduced ventilation with CO2 increase)
• Ventilatory support may be required
1ary and 2ary prevention for type 2 respiratory failure?
If the respiratory failure resulted from an overdose of sedative drugs such as morphine / heroin or benzodiazepines, then the appropriate antidote such as naloxone or flumazenil should be given.
