51 - 55 Physiology SBAs for the Primary FRCA

51 - 55 Physiology SBAs for the Primary FRCA
Photo by Nguyen Dang Hoang Nhu / Unsplash


Question 51

You have generously and deftly performed a lumbar puncture for the medical team, and the registrar decides to quiz you as you fiddle with the manometer.

Which of the following is true?

  • There is more sodium in plasma than CSF
  • There is more magnesium in plasma than CSF
  • There is less glucose in plasma than CSF
  • There is more bicarbonate in CSF than plasma
  • There is more chloride in CSF than plasma

Answer

  • There is more chloride in CSF than Plasm

CSF is essentially the same as plasma when looking at the positive ions - the numbers vary depending on where you're reading - however there's more significant difference when you look at the negative ions.

  • There is very little protein in normal CSF
  • To compensate for this, there are more chloride ions to maintain electroneutrality

Read more about CSF and head stuff here.