Respiratory Emergencies Flashcards
What is pleural effusion?
Accumulation of fluid in pleural cavity
Note: Not a diagnosis
What are the causes of pleural effusion?
1) Transudative
- Cardiac failure
- Hypoalbuminemia (eg in nephrotic or liver conditions)
2) Exudative
- Bacterial pneumonia, TB, uremia
3) Hemothorax
__________________________
4) Traumatic
5) Spontaneous
- Cancer related
- Blood dyscrasias
- Pulmonary embolism with infarction
- Spontaneous pneumothorax
What is the pathophysiology of pleural effusion?
1) Small effusions
- >300ml to be seen on X-rays
- No symptoms
2) Large effusions
- Limited lung expansion -> Reduction in vital capacity -> Hypoxia and hypercapnia
What are the clinical features of pleural effusion?
- Acute pleural pain
- Dyspnea
1) Small effusions
- No findings or
- Shifting dullness on percussion
2) Large effusions
- Dullness on percussion
- Shift of mediastinum
- Decreased chest movements
Investigations for pleural effusion?
1) XRay
- White on affected areas
What is the treatment for pleural effusion?
1) Thoracostomy drainage
- For hemothorax
2) Surgical exploration
- In causes of traumatic hemothorax
- If blood >1000mL is evacuated during thoracostomy
- If continuous bleeding from chest 150-200ml/hr for the next 24 hours
- If persistent blood transfusion is needed
What is a pneumothorax?
Collection of air in the pleural cavity
What are the causes of pneumomthorax?
1) Spontaneous
- Rupture of bullae on lung surface
- Bronchial asthma
- COPD
- TB
2) Chest trauma
- Negative pleural pressure allows air to enter
What are the clinical features of a pneumothorax?
1) Small pneumothorax
- Asymptomatic
2) Large pneumothorax
- Acute pleural pain on inspiration
- Dyspnea
- Shift of mediastinal structures
- Hyper-resonance on percussion
- Absent breath sounds
Investigations for pneumothorax?
1) XRay
- Darker on affected areas
- Marked difference in radiolucency
- Absence of vascular markings
What is tension pneumothorax?
Accumulation of air under pressure in the pleural space
Life-threatening emergency
What is the pathophysiology of tension pneumothorax?
1) Increasing pressures -> Displacement of structures and compressions of heart and vessels -> Reduces venous return/preload to R heart -> Decreases cardiac output -> Hypotension
What are the complications of tension pneumothorax?
1) Decreased VR and CO
- Hypotension and tachycardia
2) Hypoxemia (low blood O2)
- Due to alveolar collapse
3) Re-expansion pulmonary edema
- Rapid process (instead of slow) means damaged capillaries allowing more fluid leakage from increased capillary permeability and inflammatory response
4) Bronchopleural fistula (BPF)
- Sinus tract between bronchus and pleural space
- Continuous flow of air into cavity worsens pain
What are the investigations for tension pneumothorax?
1) Chest radiography
- Low quality film may miss out small pneumothorax
- Supine position avoided
2) CT
- To confirm size and presence of pneumothorax
What is the treatment for tension pneumothorax?
1) Oxygen
- Supplemental O2 speeds absorption of air from pleural space
2) Observation of stable px
- Primary: Observe for 4 hrs, home if no enlargement
- Secondary of iatrogenic: Hospitalise and observe
- May need to drain if any vital signs deterioration
3) Simple aspiration
- Use a 3-way stopcock
- Slowly evacuate until no more air at all
- If 4L of air is removed without resistance, insert chest tube
4) Chest tubes
- Small bore: Small incision, 2nd ICS if midclavicular line or 5-7th ICS if laterally
- Large bore: Blunt dissection in 3 -bottle system
5) Pleurodesis
- Stick your lung to your chest wall and prevent fluid or air from accumulating around it
What is pulmonary edema?
Excess fluid that accumulates in the lungs
What are the causes of pulmonary edema?
1) Increased venous hydrostatic pressure
- Due to left ventricular failure
2) Decreased plasma osmotic pressure
- Osmotic pressure pulls fluids to stay within the capillary
- Hypoalbuminemia
3) Altered alveolar capillary membrane permeability
- eg in ARDS
What is the pathophysiology of pulmonary edema?
1) Increased pulmonary capillary pressure
- With increased resistance of small airways
2) Pressure of >25mmHG
- Normally 15mmHG
- Increased filtration of fluid into interstitial space -> interstitial edema -> Disrupts intercellular membranes -> Collection of fluid in alveolar spaces
- Poor gas exchange
What are the clinical features of pulmonary edema?
1) Extreme breathlessness
2) Wheezing
3) Crepitations
4) X-Ray
- Kerley B lines (1-2 cm horizontal lines at the side of the lungs at the costophrenic angle)
5) Cough
- Frothy, blood-tinged sputum
- Can be copious
What is the treatment for pulmonary edema?
1) Oxygen
2) Diuretics
3) Vasodilators
What is a pulmonary embolism?
Blockage and obstruction of a pulmonary vessel by a blood-borne substance
What are the causes of pulmonary embolism?
1) Thrombus
2) Air
3) Fat
4) Amniotic fluid
5) Parasites
6) Septic emboli
7) Tumor
____________________
8a) Venous stasis
- Prolonged bed rest
- Immobilization
- Low CO
- Pregnancy
8b) Hypercoagulability
8c) Vessel wall inflammation
8=Virchow’s Triad
What is the pathophysiology of pulmonary embolism?
1) Microthrombi not removed in venous system + pulmonary vessels do not filter emboli -> Emboli reaches the arterial system -> Large clots damages lungs/heart function
2) Hemodynamic changes like increased pulmonary pressure due to obstruction -> Right ventricle strained if embolus is large -> Decreased CO
3) Change in V/Q ratio
- Decreased perfusion in area distal to obstruction
- Results in compensatory hyperventilation
4) Hypoxemia causes ischemic damage to the alveolus -> Alveolar collapse + Pulmonary edema + Decreased surfactant + Release of inflammatory chemicals
What are the clinical features of pulmonary embolism?
1) X-Ray
- Classical appearance of pulmonary infarction - Wedge-shaped lesion peripherally set against the pleura
2) Small emboli
- Tiredness
- Syncope
- Cardiac arrhythmia
3) Massive emboli
- Sudden severe central chest pain
- Marked tachypnea and dyspnea
- Shock
4) Triad onset of dyspnea, pleuritic pain and hemoptysis
5) Swollen, tender, warm calf
6) Auscultation
- Inspiratory crackles
- Pleural rub
- Wheezing
7) ECG
- Sinus tachycardia
- Deep S in lead 1
- Inverted T lead in lead 3
