Base Hospital 2003 Fall Recerts. Medical Math and Drug Calculations.
11798465 Drug Calculations
Transcript of 11798465 Drug Calculations
µgMicrograms should be written out, insist on
it!
__ ss or ss
Write out one-half or 1/2 clearly.
ODOrdered daily? Write out daily. QD, if legible,
should be acceptable.
n or N Nightly? QN? Write out nightly or use hs.
d or D Daily? Write out how many days.
BTOrdered at bedtime? Write out bedtime or
use the standard hs.
Example
Doctor's order:0.25 mg of digoxin p.o. On hand: 0.5 mg tablets
Answer
حبة تعادل نصف ملغ 1
ملغ0.25 كم حبة تعادل
X 1 =كم حبة 0.250.5
Example
Doctor's order:0.25 mg of digoxin p.o. On hand: 0.5 mg tablets
0.5 tablet
حبة تعادل نصف ملغ 1
ملغ0.25 كم حبة تعادل
X 1 =كم حبة 0.250.5
Example
Doctor's order:Give deltasone 7.5 mg PO now.Available : deltasone 2.5 mg tablet.
Answer
AVAILABLE المتوفر حاليا
Example
Doctor's order:Give deltasone 7.5 mg PO now.Available : deltasone 2.5 mg tablet.
3 tablet
AVAILABLE المتوفر حاليا
Example
Doctor's order:Give ranitidine 40 mg PO ABT.Available is ranitidine 20 mg tabletHow many tablet you should give?
Answer
Solution
40 X 120
4020
2 tablets
ABT عند النوم
Example
Doctor's order:Give 7500 i.u of heparin injection S/C .Available:( heparin injection 5000
i.u/ml)How many ml you should give?
Answer
Solution
7500 X 15000
75005000
1.5 ml
Example
Doctor's order:Give 500 cc D5RL to be infused in 6
hrs. You should regulate the I.V at:
Answer
Solution
500 cc X 156 hrs X
60 m
7500
360
21 drop/m
دائما يعتبر عامل التنقيطال اذا ذكر في السؤال15
غير ذلك
المعادلة)عامل التنقيط xالكمية بالمل )
مقسومة على)دقيقة X 60عدد الساعات )
Example
Doctor's order:Give 1500 cc normal saline over 4 hrs. You should regulate the I.V at:
Answer
Solution
1500 cc X 154 hrs X
60 m
22500
240
94 drop/m
دائما يعتبر عامل التنقيطال اذا ذكر في السؤال15
غير ذلك
المعادلة)عامل التنقيط xالكمية بالمل )
مقسومة على)دقيقة X 60عدد الساعات )
Example
Doctor's order:Give 1000 cc dextrose 5% I.V Q 8 hrs. You should regulate the I.V at:
Answer
Solution
1000 cc X 158 hrs X
60 m
15000
480
31 drop/m
دائما يعتبر عامل التنقيطال اذا ذكر في15
السؤال غير ذلك
exit
Example
Doctor's order:Give 3 L of I.V fluid 5% D/0.45%
normal saline over 24 hrs.(the drop factor is 60 gtt/ml).
You should regulate the I.V at:
Answer
Solution
3000 cc X 6024 hrs X
60 m
180000
1440
125 drop/m
دائما يعتبر عامل التنقيطال اذا ذكر في السؤال15
غير ذلك
Example
Doctor's order:Give 3000 cc dextrose 5% I.V Q 6 hrs,
drop factor is 20 gtt/m)How many drops should you give per
minute?
Answer
Solution
3000 cc X 206 hrs X
60 m
60000
360
166.66 (167)
دائما يعتبر عامل التنقيطال اذا ذكر في السؤال15
غير ذلك
Example
Doctor's order:Give penicillin 600.000 u I.M statAvailable: (penicillin 800.000 u/2 cc)How many ml should you give?
Answer
Example
Doctor's order:Give penicillin 600.000 u I.M statAvailable: (penicillin 800.000 u/2 cc)How many ml should you give?
1.5 ml
Example
Doctor's order:Give G/S 2000 cc I.V Q 24 hrs,The rate will be how many drop per
minute?
Answer
Example
Doctor's order:Give G/S 2000 cc I.V Q 24 hrs,The rate will be how many drop per
minute?
21 drop/m
Example
• The physician orders IV fluids to hydrate a client. The order is written as "D5NS 4 Liters over 24 hours." Looking at the package indicates the drip factor of the tubing is 15 gtt/ml. What is the drip rate?
Answer [email protected]
Example
• The physician orders IV fluids to hydrate a client. The order is written as "D5NS 4 Liters over 24 hours." Looking at the package indicates the drip factor of the tubing is 15 gtt/ml. What is the drip rate?
42 gtt/m
:Shortcut method when you know the ordered ml/hr
gtt/ml: divide the ml/hr by 4 15
gtt/ml (typically blood products): divide ml/hr by 6 10
gtt/ml: divide ml/hr by 3 20
4 / 175 = 43.75
gtt/min
6 / 175 = 29.16
gtt/min
3 / 175 = 58.33
gtt/min
Example
•The client's K+ is 2.0 mEq/dl and the physician orders a potassium bolus of 40 mEq of KCl in 200 ml of NS to
be delivered at a rate of 10 mEq/hr. What is the drip rate inmicrodrops ?
(.(Ideal, deliver on a pump
•This is a two-part problem. •Calculate the concentration of the KCl in the NS using ratio and proportion
mEq 40
ml 200 = mEq 10
x ml
40x
= 2000
x = 50
• Now you can use the IV formula.
ml 50
60 min x gtt 601 cc
x 60 50 = 3000
60 / 3000 = 50
Answer: 50 (microgtts/min)
Calculating flow rate
• Flow rate refers to number of ml of fluid to be infused over one hour (ml/hr).
)total # of milliliters )volumetotal # of hours = X ml/hr
Example
• The nurse makes rounds and notes that the current IV bag contains approximately 450 ml. The IV flow rate is 150 ml/hr. How long will it be before the nurse must hang a new bag?
Answer exit
Example
• The nurse makes rounds and notes that the current IV bag contains approximately 450 ml. The IV flow rate is 150 ml/hr. How long will it be before the nurse must hang a new bag?
3 hrs exit
Example
• Order: Administer 1000 cc at 50 gtt/min.
Answer
exit
Example
• Order: Administer 1000 cc at 50 gtt/min.
5 hrs
exit
Example
• John is to receive Cleocin 150 mg IV q 8 hours. The nurse dilutes the medication to a total volume of 30 ml and plans to deliver it via an infusion pump over thirty minutes. What would be the flow rate?
Answer exit
Example
• John is to receive Cleocin 150 mg IV q 8 hours. The nurse dilutes the medication to a total volume of 30 ml and plans to deliver it via an infusion pump over thirty minutes. What would be the flow rate?
60exit
Example
• For the client whose weight is 130 lbs and has dopamine ordered at 8 mcg/kg/min, what rate should the infusion pump be set for a solution of 400 mg dopamine in 250 ml D5W?
Answer
exit
• Client's weight: 130 lbs • Dosage: 8 mcg/kg/min • Solution: 400 (mg) in 250 (ml)
Tip• Convert wt to kg. 130 / 2.2 =
59.09 kg• Find concentration of dopamine in
1 cc. mg 400 250 ml
=x mg 1 ml
250x = 400
x = 1.6
• 3) Concentration is 1.6 mg /cc.
Convert the mg to micrograms. • 1.6 (mg) x 1000 (mcg per 1 mg) =
1600 mcg/cc.Now that you have gathered all the information, plug it into the
formula
unit"/kg/min) ") 8 X 59.09 )wt in kg)X 60 )min/hr) )1600 )"unit" / ml =
28363.32
1600
x = 17.727
17.727 or 18 ( ml/hr) will dialed on the pump
Example
• A client is receiving dopamine at 12 ml/hr. The solution hanging indicates "D5W 250 ml/200 mg dopamine". The client weighs 133 lbs. What is the dosage (mcg/kg/min) the client is receiving?
Answer exit
• Flow rate: 12 ml/hr
• Solution: 200 mg dopa / 250 cc D5W
• Client's weight: 133 lbs
Tip1) Convert wt to kg. 133 / 2.2 =
60.45 kg 2) Find concentration of dopamine
in 1 cc.
mg 200 250 ml = x mg
1 ml
250x = 200
x = 0.8
3) Concentration is 0.8 mg/ml. Convert mg to mcg.
0.8 (mg) X 1000 (mcg per 1 mg) = 800 mcg /ml.Now that you have gathered all
the information, plug it into the formula.
The dosage the client is receiving is 2.65 mcg/kg/min.
ml/hr) ) 12X 800 ("unit"/ml) (Time) 60 min/hr X( 60.45 (weight in kgs =
9600
3627
X = 2.65
Example
• A client is receiving a heparin drip at 22 ml/hr via an infusion pump. The label on the liter bag of D5W indicates 40,000 U of heparin. How many units of heparin does the client receive per hour?
Answer [email protected]
U 40,000 1000 ml = x U
22 ml
1000x = 880,000
x = 880
.The client is receiving 880 U of heparin per hour
3) Concentration is 0.8 mg/ml. Convert mg to mcg.
0.8 (mg) X 1000 (mcg per 1 mg) = 800 mcg /ml.Now that you have gathered all the information,
plug it into the formula.
The dosage the client is receiving is 2.65 mcg/kg/min.
ml/hr) ) 12X 800 ("unit"/ml) (Time) 60 min/hr X( 60.45 (weight in kgs =
9600
3627
X = 2.65
Example
• The physician becomes concerned about John’s renal function and orders the Vancomycin dose (60 mg) to be infused over 90 minutes instead of the usual 60 minutes. If the Vancomycin dosage is diluted into 60 ml of IV fluid, what will be the flow rate? (Given on an IV pump for control.)
Answer
ml 60 90 min
=
X ml 60 min
x 90 = 3600
x = (ml/hr) 40
exit
Example • John's primary IV is running at 34 ml/hr while
NPO. When the nurse runs the Vancomycin (250 mg IV q 8 hr) in over 90 minutes [volume is 100 ml--(2 50 ml syringes)], the primary IV is stopped. The ampicillin (395 mg IV q 6 hr) is given concurrently in 10 ml of fluid over 30 minutes. He received 2 boluses of aminophylline (20 ml each over 20 minutes). The IV fluids were stopped while the aminophylline infused. Since microtubing was used for the medications, total flush is negligible (approximately 3 ml). What is John’s total intake for 24 hours?
Answer exit
Vancomycin runs for 1.5 hrs x 3 doses .hrs IV is stopped 4.5 =
Primary or maintenance IV :fluids
hr) minus 4.5) 24 .hrs 19.5 =
Primary fluid is stopped while:aminophylline is infusing
min x 2 20 minutes 40 =
hr 30 minutes minus 19 40 minutes
hr 50 minutes )18.84 hrs) 18 =x 34 ml
ml 640.5 =
Vancomycin : cc x 3 100 =300.ml
Ampicillin: cc x 4 10 =40.ml
Aminophylline: cc x 2 20 =40.ml
Normal salineflush:
)approximate) = 3ml
3 + 40 + 40 + 300 + 640.5 = .ml / 24 hrs 1023.5
.John's daily intake, based on all therapeutic modalities, is 1023.5 ml
Example
• Crystal has an IV infusing at KVO (10 ml/hr). She receives an antibiotic in 22.5 ml q 8° concurrently. One ml flush is given after each antibiotic. She is given 30 ml of formula q 3°.
• She had diaper weights of 17 ml, 33 ml, 55 ml, 45 ml, 52 ml, 50 ml, 15 ml, and 36 ml.
• Calculate her I & O for the past 24 hours.
Answer
Intake:
IV @ 10 ml/hr x 24 hr = 240 ml
Med of 22.5 ml x 3 )q8°) = 67.5 ml
Flush of 1 ml x 3 = 3 ml
Formula of 30 ml x 8 )q 3°) = 240 ml
.Crystal's intake is 550.5 ml for the past 24 hours
Output:
36 + 15 + 50 + 52 + 45 + 55 + 33 + 17 ml 303 =
.Crystal's output is 303 ml for the past 24 hours
Example
• John also has an order for ampicillin sodium 395 mg IV q 6 hr. The safe range for his type of infection in the literature is 100-200 mg /kg /day. Is this a safe dose?
Answer
Calculate the recommended range: •Minimal: 100 mg x 20 kg = 2000 mg •Maximal: 200 mg x 20 kg = 4000 mg
Recommended range is 2000 - 4000 mg. Actual dose is: 395 x 4 )q 6 hr) = 1580 mg
/ day Compare the two values. The actual dose is less than the recommended dose. Dose is “safe”, but not necessarily therapeutic.
Example
• The physician stopped John’s gentamicin and cleocin when the culture report came back. His new orders include Vancomycin 250 mg IV q 8°. The literature indicates that the minimal dilution concentration for infusion should be 2.5 mg / ml if given through a peripheral intravenous line (PIV). How many ml of diluent will the nurse need to mix the Vancomycin to meet this safety requirement?
Answer
Example
• The physician stopped John’s gentamicin and cleocin when the culture report came back. His new orders include Vancomycin 250 mg IV q 8°. The literature indicates that the minimal dilution concentration for infusion should be 2.5 mg / ml if given through a peripheral intravenous line (PIV). How many ml of diluent will the nurse need to mix the Vancomycin to meet this safety requirement?
100 ml
Example
• A newborn has an order for 0.15 micrograms of Prostin VR (alprostadil) per hour to maintain patency of the ductus arteriosus. The pharmacy prepared a Prostin drip with 25 mcg alprostadil in 50 ml of D5W. What hourly rate is needed to deliver the dosage of medication as ordered?
Answer
Example
• A newborn has an order for 0.15 micrograms of Prostin VR (alprostadil) per hour to maintain patency of the ductus arteriosus. The pharmacy prepared a Prostin drip with 25 mcg alprostadil in 50 ml of D5W. What hourly rate is needed to deliver the dosage of medication as ordered?
0.3 ml/hexit
Example
• John is to be given an Aminophylline bolus of 30 mg in 20 ml of fluid over 20 minutes. The primary IV is running at 40 ml/hr. The drip factor of the tubing (buretrol) is 60 gtts/cc or minidrip. What is the flow rate needed to deliver the Aminophylline bolus as ordered?
Answer exit
Example
• John is to be given an Aminophylline bolus of 30 mg in 20 ml of fluid over 20 minutes. The primary IV is running at 40 ml/hr. The drip factor of the tubing (buretrol) is 60 gtts/cc or minidrip. What is the flow rate needed to deliver the Aminophylline bolus as ordered?
60 ml/hexit
Example
• John is a pediatric client in a hospital in which the policy is to place all children on IV therapy on a buretrol and to only fill the buretrol no more than two-three hours worth of fluid. The nurse fills the buretrol to 90 ml at 10 a.m. If John’s IV is running at 34 ml per hour, how long will it be before the nurse will need to fill it again?
Answer exit
90 ml ÷ 34 (ml/hr) = 2.65 hrs However, 0.65 hrs = ? minutes
hr 1
60 min = hr 0.65
X min
1x = 39.00
X = 39
Answer = 39 minutes Add this to the 2 hours. 10 a.m. + 2 hr 39 minutes = 12:39
p.m.
At 12:39 p.m. the buretrol will need more fluid added so that air does not get
into the tubing. [email protected]