ECG's, Bloods & CXR Flashcards
(32 cards)
Put the following in order of density (least=radio-lucent to most=radio-opaque) on chest X-Ray
- Fat
- Bone/free blood
- Air/gas
- Water
- Metal/contrast dyes
Air/gas (black) Fat (grey) Water (pale grey-white) Bone/free blood (white) Metal/contrast dyes (white)
Name 4 mechanisms of lung collapse.
- Hypoventilation
- Obstruction (resorption)
- Positive intra-pleural pressure (compression)
- Surfactant impairment
What are the degrees of lung collapse?
- Atelectasis
- Segmental
- Lobar
- Lung
How can you identify a collapse on CXR?
- Loss of volume
- Movement of adjacent structures towards the collapse
- Silhouette sign
What is consolidation?
Pathological condition where air is replaced in the lung with tissue or fluid of greater density
Causes of consolidation?
- Fluid exudation (pulmonary oedema)
- Exudation (infection or pulmonary haemorrhage)
- Inhalation (gastric contents, toxic fumes)
- Infiltration (lymphoma, alveolar cell carcinoma)
What are the differences between consolidation and collapse on CXR?
Consolidation > Collapse
Normal volume > Reduced volume
No shift of structures > Shift towards collapse
Vascular markings obscured > Vascular markings present and close together
Air bronchogram (black airway visible against white lung field) > No air bronchogram
Causes of pneumothorax?
- Stab wound
- Mechanical ventilation high pressures
- Spontaneous rupture subpleural bleb
- Misplacement subclavian line
- Chest trauma and # ribs
What is a pneumothorax?
Air in the pleural cavity
Pleural effusion
Fluid in the pleural space.
What will pleural effusion look like on CXR?
- Blunting of costophrenic angle
- White opacity (gravity dependent)
- No loss of volume
- Fluid line observed in erect position
What would you expect to see on a COPD CXR?
- Bullae
- Hyperinflation
What are some causes of pulmonary oedema?
- Left ventricular failure
- Renal failure
- IV fluid overload
- Drug abuse
- Neurological events
- ARDS
What is ventilation?
What is perfusion?
Ventilation = Air that reaches the lungs Perfusion = Blood that reaches the lungs
Where does optimal V/Q matching occur?
Dependent region (lower 1/3 of the lungs)
What happens when there is poor ventilation?
Shunt. Perfused area of lung but not ventilated
What happens if there is poor perfusion?
Physiological dead space. Ventilated lung but not perfused, does not participate in gas exchange.
98.5% of O2 is transported where?
Where is the rest?
Binded to haemoglobin on RBC’s.
Dissolved in plasma.
Where is 60-70% of CO2 transported?
In a dissolved state as bicarbonate.
What are two methods of monitoring blood gases?
- Non-invasive (clip on/external attachment eg. pulse oximeter)
- Invasive (via inserted attachment, eg. IV or arterial line)
What are some common insertion locations for arterial lines?
- Radial artery
- Brachial artery
- Femoral artery
What are the two key buffer systems for maintaining the bodies acid-base balance?
How long do these systems take to respond?
- Respiratory (mins-hours)
2. Renal (days)
pH measure ____ concentration which is kept in balance by maintaining _____ and _____ in a constant ratio.
H+
Bicarbonate ions (basic)
PaCO2 (acidic)
What are normal values for the following:
- pH
- PaCO2
- PaO2
- HCO3
pH = 7.35 - 7.45 PaCO2 = 35-45mmHg PaO2 = 80-100mmHg HCO3 = 22-26mmHg
