I'm having problems determining the correct volume to use when calculating IVPB flow rates.
I'm using the V/T x C = R equation.
Example 1 from my text:
cimitidine 250mg q6h in 50 mL D5W IVPB to be infused in 20 minutes
available 300 mg/2 mL of cimitidine
drop factor 10 drops/mL
I calculated that you would give 1.7mL of cimidine
I would think you would add the 1.7mL to the 50mL then calculate V/T x C = R.
The book has us calculating 50mL, not 51.7mL as V.
Using 50 mL you get 25 gtt/min, using 51.7 mL, you get 26 gtt/min.
Which one is right?
theophylline 100 mg in 50 mL of D5W x 30 minutes q6h IVPB
theophylline available 80 mg/15mL
drop factor is 60 gtt/mL
I calculated to give 18.8 mL of theophylline.
The book adds the 18.8mL to the 50mL to give 68.8 mL for the Volume.
Why is this one added? Why would you use 68.8 and not 50mL for Volume.
Using 50 mL for Volume, you get 100 gtt/min. Using 68.8 for Volume, you get 138 gtt/min.
The correct answer in the book is 138 gtt/min.
When do you add them together? It doesn't say in the book? Is it a certain mL? If you have less than 5mL do you not add?