Quote from Crunktastic
Hey everyone! I need some help with this problem. I want to know how to work it out, not just the answer please! Any help would be very much appreciated!
A 10 year old child is to receive Zosyn 750 mg IVPB q12h. The drug book states: dilute 10-20 mg/ml and administer over 30 minutes. The pharmacy has sent up Zosyn 800 mg in 15 ml. How should the nurse dilute and administer this medication?
A. Add medication to a 25 ml bag of fluid and administer at 80 ml/hr with a VTBI of 40.
B. Add medication to a 50 ml bag of fluid and administer at 100 ml/hr with a VTBI of 50.
C. Add medication to a 100 ml bag of fluid and administer at 230 ml/hr with a VTBI of 115.
This is a lousy problem because none of the choices is actually correct... However, answer {C} is arguably the best of the three.
For simplicity, I'll just brute-force it and solve each choice...
{A}
Find the concentration
800 mg
----------------
15 mL + 25 mL
800 mg/40 mL = 20 mg/mL (acceptable, at the high end of the range)
Calculate the quantity (mass, actually) of medicine given:
20 mg/mL x 40 mL = 800 mg (too much... by 7%)
Calculate the administration time:
40 mL
-----------
80 mL/hr
40/80 = 0.5 hours or 30 mins (acceptable)
{B}
Following same approach:
Concentration = 800 / (50 + 15) = 12.3 mg/mL (acceptable)
Quantity = 12.3 mg/mL x 50 mL = 615 mg (too low by 18%)
50/100 = 30 min (acceptable)
{C}
Following same approach:
Concentration = 800 / (100 + 15) = 7 mg/mL (too low... though not really problematic)
Quantity = 7 mg/mL x 115 mL = 805 mg (too high by 7%)
230/115 = 30 min (acceptable)
I pick choice {C} because the lower concentration is easier on the veins but still delivers the requisite amount of medication in the ordered time. One could argue in favor of {A} by stating that the smaller volume is preferable in a child but a 10-year-old probably weighs about 35 kg or so and a volume of 3 mL/kg is pretty minimal and not likely to create any issues in a kid without renal or cardiac problems.
I wouldn't be cool giving a dose 7% higher than the one ordered, though... would have to seek MD clarification before I gave it...
Or better yet, just add the 15 mL dose to a 50 mL bag and give 61 mL at 122 mL/hr... and say "pshaww" to stupid multiple-choice questions....