by Andy
(Ohio)
I'm practicing for my board exam, and I'm stumped on this particular practice question:
A patient needs IV infusion of 0.9% NaCl. You have water for injection and 4.5%w/v stock solution of NaCl. There are no displacement volume effects. How much of the 4.5% w/v needs to be added to a 1L WFI bag to produce the desired concentration?
I've tried alligation and the (IS)(IV)=(FS)(FV) methods, and both times I've come to 200 mL of the 4.5%w/v solution. However, that is not one of the choices available. Am I doing something wrong in my calculations?