by Raul24 » Wed Apr 06, 2011 4:42 am
[quote="lisa"]I'm in pharamcy class the question is a given a Heparin concentration of 10,000units ml, how many mls of heparin are needed for the following
30,000 units /1000 ml D5W at 1,000 units /hr ml
20,000units/1000ml NS at 1,300 units /hr ml
25,000units /500ml D5W at 1,200 units/hr
Now determine the flow rate in ml/hr
a b c[/quote=Raul"]
Using Dimensional Analysis: (DA) the mL required to match the Heparin dose needed to be included into the IV solutions ( [#1] 30, 000 units in 1000 mL, [#2] 20,000 units in 1000 mL and [#3] 25, 000 units in 500 mL) is calculated as follows:
mL = 1 mL x 30, 000 units = 3 mL mL = 1 mL x 20, 000 units = 2 mL
10,000 units 10,000 units
mL = 1 mL x 25, 000 units = 2.5 mL
10, 000 units
Please notice that for this to be exact and according to the 3 sets of problems as listed, in [#1] 3 mL of the given Heparin concentration (10, 000 units/mL)
will be added to 997 mL of D5W [997mL+3mL =1000 mL] this is 30, 000 units in 1000 mL, in [#2] 2 mL of Heparin will be added to 998 mL of NS [998mL+2mL =1000 mL] this is 20, 000 units in 1000 mL, and finally in [#3] 2.5 mL of Heparin will be added to 497.5 mL of D5W, this is 25,000 units in 500 mL. (if you instead add 3 mL, 2 mL and 2.5 mL to 1000 mL, 1000 mL and 500 mL respectively in each problem the discrepancy will be minor)
Now that you have calculated and compounded the IV solution with the heparin as required you can use (DA) again to calculate the flow rate:
mL = 1000 mL x 1000 units = 33.33 mL/hr (need to round down) = 33 mL/hr for [#1]
30, 000 units 1 hr
mL = 1000 mL x 1300 units = 65 mL/hr (exact division) [#2]
20, 000 units 1 hr
mL = 500 mL x 1200 units = 24 mL/ hr [/b](exact division) [#3]
25, 000 units 1 hr