Primary Viva 11 (Physics)

Part I

1. Discuss pressure measurement in general and non-invasive blood pressure monitoring in particular
2. Discuss the principles of the mercury sphygmomanometer.
– Why is it open at the top?
– What is the significance of cuff size, and what happens with large and small cuffs? What are the complications of cuffs?
3. Draw a diagram of the Bourdon gauge.
– What happens if the tube at end, near the pointer, is broken?
4. What are the units of pressure?
– What is the definition of a Pascal
5. Which is higher, the pressure developed in a 2 ml or a 20 ml syringe and why?
– In which syringe would you be able to clear a blockage?
6. How does a pressure transducer calculate pressure? (mention the word “integration” for measuring the mean arterial pressure!)

Part II

1. You are presented with three curves and their logarithmic transformation.
– Explain the curves, and how they can each be identified. Give examples of particular curves which would fit these patterns and explain how you would interpret them
 – What are the equations describing the curves?
– How would you calculate the various values from the curves (especially the negative exponential curve)?
2. Discuss the concepts of half-life and time constant.
– What are the differences between these functions?
– What amount of function remains at the end of 1, 2 and 3 time constants?
– Explain graphically the concepts of both the half-life and time constant.
– Why are curves logarithmical?

Part III

1. What considerations should be taken before building a vaporiser?
2. You are shown a diagram of an opened up Tec vaporiser.
– Identify the pathways inside and discuss the structure.
– Show the variable bypass and explain what  it means.
– What happens if 100% of the gas is passed through the vaporisation chamber?