05 February 2009

Dopamine and Dobutamine Computation

Infuse Dobutamine 500 mg in 250 ml D5W at 5 mcg/kg/min using microdrip tubing. The client weighs 182 lbs. Determine the ml/hr and the gtts/min.

How do you solve this problem?
All you need to do is to understand the problem and to memorize your conversion.

Step 1 - Know the given: 
  • 500mg/250ml (may 500mg na Dobutamine sa bawat 250mL na hawak mong gamot galing pharmacy/stock dose)
  • 5mcg/kg/min (5mcg sa bawat kg na bigat ng patient per minute ang ibibigay/main order ng Dr.)
  • 182 lbs (182 lbs ang timbang/weight ng patient mo)
Step 2 - Know what is asked:
  • mL/hr (Ilang mL ang ibibigay mo bawat oras?)
  • gtts/min (Ilang gtts per minute ang setting mo?)

Step 3 - Solve the problem:

  • Find the dosage for every total weight of the patient 
a) Convert the weight from lbs to kg. (1kg/2.2lbs) ang conversion so the answer is 82.7kg 
b) Multiply 82.7kg by 5mcg (dahil sa bawat kg weight ng patient magbigay ka daw ng 5mcg) the answer is 413.5mcg/min (eto na ngayon yung main order ng Dr. per total weight of the patient)

  • Convert your stock dose so that you can cancel the units or use the popular formula D/S*Q
a)Convert 500mg to mcg. Use (1mg/1000mcg) the answer is 500,000mcg. You now have 500,000mcg/250mL 

  • We can now use the popular formula D/S*Q (desired / stock * quantity)
a) desired - 413.5mcg
b) stock - 500,000mcg
c) quantity - 250ml

413.5mcg / 500,000mcg * 250ml = (0.20675ml/min) 
(saan nanggaling yung min sa ml/min? = Dito po: 413.5mcg/min)

What is asked:
a) mL/hr? - your answer is in minutes so you just have to multiply by 60, the answer now is 12.4mL/hr
b) gtts/min? - cc/hr or mL/hr IS THE SAME WITH ugtts/min (Remember that!) So the answer is 3 gtts/min from our answer na 12.4 ugtts/min divided by 4 to get the gtts/min.

mahirap yata i-set yung 3gtts/min, mali siguro yung question baka ugtts yun, sabi din kasi use microdrip. I got the question here: LINK Visit this link, maganda din explanation dyan.

NOTE: Stock dose varies, there is what we call Double dose which simply means that the dosage of the stock medicine is greater. Just check the label and compute as is. Don't worry about NCLEX-RN questions about Double or Triple dose, they will surely provide you with the exact stock dosage and details because they don't give vague questions, after all we are dealing with lives.

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  1. the answer 3gtts/min is wrong..

    12.41 ml/hr x (1 hr/60 min) x (60gtts/ml) =
    = 12.41 gtts/min...

  2. to anonymous above:

    kung ang drop factor mo is 60 (microdrip tube) then 12 ang sagot, if 20 then 4 or kung 15 then 3 ang sagot, in this case 15 yung ginamit kasi drops/min yung hinahanap hindi microdrops(ugtts)

    yung (60ugtts/mL) yan yung nagiiba, pwede din yan maging 20gtts/min or 15gtts/min depende sa drop factor. and in this case sabi nga sa observation bakit ka gagamit nang macro set mali nga yung tanong. tama po ba?

  3. Thanks. Very helpful sa mga nagrerecall like me. ^_^ Mahirap nga i-regulate ang 3gtts/min,siguro nag-assume yung nagtanong nyan na gagamit ka ng infusion pump. Or just use microset,and the ugtts/min para kayang iregulate manually. ;)

  4. may mas mdaling computing tech.

    wt (kgs) x therapeutic dose devide sa 16.6=single dose

    82.7x5 /16.6/2 (double dose)= 12.4

    sa hospital prating microset (60 dripping factor) ang ginagamit..

    jun (ER nurse)

  5. the answer is 20.15 drops per minute..

    250ml x 60 gtts/min

    12.41 ml/hr x 60 min

  6. sir jun pano mo nakuha ung therapeutic dose? ung 16.6 atsaka ung double dose? paturo ako :) please tahnky ou

  7. hello po!if me nakakabasa nito, triny ko po ung way ko pagsolve ng dopamine sa problem ng dobutamine prob eh same po ung answer ng 12.4ml/hr... eto po ang link sa youtube... mas madali po actually...

  8. hello po! we arrived at same answer po which is 12.4ml/hr pro ung formula na ginamit ko is ung sa pagsolve ng dopamine problem... eto po ang tutorial nakita ko sa youtube...mas simplified po and youre dealing with small numbers lng po..

  9. I think ung 16.6 is a constant... Kpag nman dopa, 13.3 ang constant...these are for single dose constant..

  10. Hi everyone. The formulas and step by step procedure has been helpful. I want to share the other formula that we are using to make it simple. I hope it will also help the other reviewees:

    To find the cc per hour, first we need to calculate the concentration. We know that the given above is a double concentration of dopamine (33.33). Just to show how it was taken, the ff. formula was used:

    (Stock/vol) x (1,000mcg/1mg) divided by 60mgtts/ml

    =500mg/250ml x (1,000mcg/1mg) divided by 60mgtts/ml

    = 33.33 mcg/mgtts (concentration)

    To find cc/hr

    = desired dose x weight divided by conc.

    = 5mcg/kg/min x 82.7kg divided by 33.33mcg/mgtts

    =12.4 mgtts/min (which is the same with cc/hr)


Thank you for your comments.

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