|1. Describe the mechanism of action of pH electrodes and CO2 electrodes.
- Describe errors in the measurement of CO2 and pH while taking arterial blood gases (ABG).
- What are the two calibration points for the pH electrode in the ABG machine?
- How does the ABG machine calibrate CO2?
2. You are shown photographs of various methods of measuring temperature (e.g. oesophageal probe, mercury thermometer, Bourdon gauge thermometer, bimetallic strip) and asked various questions on them.
- Draw the thermistor resistance curve
- What are the advantages and disadvantages of a thermister?
- What are the principles and disadvantages of a mercury thermometer?
- What is the Seebeck effect?
- What are the two metals used in this effect?
- What is the composition of constantan?
3. You are shown photographs of various endotracheal tubes: an 8.0 RAE, a standard 8.0, and an uncuffed 4.0.
- Of these, which will have the highest resistance and why?
- Explain the Poiseuille formula.
- Which is the site of highest resistance in a circuit with an endotracheal tube?
- Why is the 4.0 endotracheal tube uncuffed?