MATH 102 WEEK 04 SESSION 01 AGENDA SU 09
Professor Luke Papademas
papademas@aol.com
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Welcome to MATH 102 Medical Mathematics
Meet: Mondays - Thursdays 6 PM
Room 2109
Meet: Wednesdays 6 PM
Room 1836 ( Professor James )
Sometimes in the PC Lab Room ( Wednesday )
Avoir Du Pois Extra Credit ( consider cereal boxes
and balance weights )
Online Web site:
http://www.papademas.net/occ/MATH102
Final Exam on Thursday
Covers up to Chapter 1 - 10
Lab Projects Wednesday ( MS Excel – calculations, MS Internet
Explorer – interactive Web applications )
Review Chapter 8 ( Calculations of Basic IV Drip Rates )
Cover Chapter 9 ( Special Types of Intravenous Calculations )
Graded work tonight / tomorrow ( webcourses@aol.com )
Monday’s Deliverables include: Homework 6 and 7
Tuesday Homework 8
Thursday Homework 9 / 10
Page 210
Chapter 8
Example – Determining Hours an IV will Run ( time calculations )
Order:
500 mL NS IV ; infuse at 75 mL / hr
Rule:
Number of mL
500 mL
___________
=
_______
Number of mL / hr
75 mL / hr
=
The IV will last approximately 6.7 hours.
2 / 3 hr = (2 /3) ( 60 ) = 40 minutes
We could have used
6.6666
but … we use the traditional rules of rounding
6.7 hrs
6.7 = 6 + 0.7 = 6 hours + 0.7 hours = 6 hours + 0.7 * 60 minutes
Page 211
Example:
Order:
Aminophylline 500 mg in 250 mL D5W IV at 50 mL / hr
Rule:
Number of mL
___________
Number of mL / hr
=
250 mL
___________
50 mL / hr
=
5 hr
Self – Test 2 IV Infusions - Hour
9.
hr
(Page 212)
Calculate the hours that the IV orders will run.
Order:
1000 mL NS IV 12 NOON – 6 PM
Rule: we know that between 12 NOON – 6 PM = 6 hours
Theoretically we would have:
1000 mL
___________
166.67 of mL / hr
=
6 hr
Choosing the Infusion Set
Use Microdrip when ….
-
IV administered over a long period
a small amount of fluid is to be infused
Use Macrodrip when ….
-
the order specifies a large amount of fluid over a short time
-
the microdrips per minute are too many and counting the drip
rate becomes to difficult
Continuous observation is necessary
Adding Medications to IVs
Example ( Page 213 )
Order:
Available:
1000 mL D5W with 20 mEq KCL IV 10 AM – 10 PM
vial of KCL 40 mEq /20 mL, microdrip ( 60 gtt / min ),
macrodrip ( 20 gtt / min )
x =(D/H )*S =
Formula Method
x =(D/H )*S = / * ( )
x = ( 20 mEq / 40 mEq ) * 20 mL
x = 10 mL
Hence, we add 10 mL of KCL to the IV bag.
Step 2 : Choose the tubing
We know that the IV will run in 12 hours ( 10 AM – 10 PM ).
12 * 60 = 720 minutes
Number of mL to infuse * TF
______________________
Number of minutes to infuse
For macrodrip:
1000 mL to infuse * 20 gtt / min
______________________
720 minutes
For microdrip:
=
28 gtt / min
1000 mL to infuse * 60 gtt / min
______________________
720 minutes
=
83 gtt / min
Page 214
Self - Test 3 IV Infusion Rates
Calculate how much medication is needed ( if applicable ) and the
infusion rate.
1.
Order: 500 mL D5W IV with vitamin C 500 mg of 60 mL / hr
Available: ampule of vitamin C labeled 500 mg / 2 Ml ; microdrip
tubing at the 60 gtt / mL
Rule:
500 mL
___________
60 mL / hr
=
8.3 hr
8.3 = 498 minutes
For microdrip:
500 mL to infuse * 60 gtt / min
______________________
498 minutes
=
60 gtt / min
Run at: 60mL / hr which is the same as a microdrip rate;
3.
Order: Aminophylline 250 mg in 250 mL D5W IV; run 50 mL / hr
Available: infusion pump; vial of aminophylline labeled 500 mg / 10 mL
Rule:
250 mL
___________
50 mL / hr
=
5 hr
Since we have an infusion pump – the work is done for you!
Page 217
Example:
Order: Vancomycin 1 g IVPB 7am
Supply: 500mg powder
Package insert directions: 250mL (1g)/D5W
Run over 2 hours (1g). Refrigerate for 7 days.
Use a reconstitution device to add 1g vancomycin (two vials of 500mg) to
250mL D5W. Label the IV. Set the rate at 21 gtt/min. The IVPB will run 2
hours.
mL x TF
-------- = gtt/min
Min
250x10
--------- = 250 20.8 = 21 gtt/min
120
12 )250.0
Use Macrodrip when ….
-
the order specifies a large amount of fluid over a short time
-
the microdrips per minute are too many and counting the drip
rate becomes to difficult
Self-Test #4
2.
Order:
Ceptaz (ceftazidime) 1g IVPB q12h
Supply:
1 g powder
Package directions: 50mL (1g)/D5W. Infuse in 15-30 minutes/store for 7
days (REFRIGATED)
Available: macrodrip tubing at 10gtt/mL
RULE:
mL X TF = gtt/min
min
50mL X 10 = 50 = 16.6 = 17 gtt/min
30mins
3
Example pg 219
Administer ½ strength Isocal at 60mL/hr. The total volume will equal 250
mL.
For this problem, begin by taking ½ of the total volume to infuse:
½ × 250 mL = 125 mL
This number tells you how much formula to add to the tube feeding bag.
Next, subtract that number from the total volume.
250 mL – 125 mL = 125 mL
This new number tells you how much water to add to the tube feeding bag.
Now that you have diluted the formula to ½ strength, infuse it at 60mL/hr.
Self Test # 5 pg 220
1. 25 % Renalcal must be prepared. 400mL is the total volume. How
much Renalcal is to be mixed with how much water?
.25 * 400mL = 100 mL
400 mL – 100 mL = 300 mL
100mL Renalcal. 300 mL water
Self Test # 6 pg 221
6. A patient is receiving an antibiotic IVPB in 50 mL q8h to run over 1
hour plus a maintenance IV of 100 mL/hr. What is the 24 hr intake
parenterally?
50 mL * 3 = 150 mL
100 mL * 21 hr = 2100 mL
2100mL + 150 mL = 2250 mL
Self Test # 7 page 222
6. Order: Amikin (amikacin) 0.4 g IVPB q8h
Supply: 2-mL vial labeled 250 mg/mL
Package directions: 100 mL/D5W 30 minutes
Available: macrodrip tubing 10 gtt/mL
a. How many mL of amikacin should be added to the IV?
1 mL
250mg
=
x
400mg
X = 1.6 mL of amikacin
b. What are the gtt/min?
Add 1.6 mL Amikin to 100 mL D5W
TF = 10 gtt/mL for IVPB, total min: 30
mL × TF = gtt/min
min
100mL × 10 = 33.3 = 33 gtt/min
30 min
Label the IV.
Set the rate at 33 gtt/min.
Example pg 237-238
Heparin is mixed 25,000 units in 500 mL D5W.
How much heparin is in 1 mL of fluid?
25000 units
500 mL
=
x
1 mL
X= 50 units
Example pg 238-239
Order: heparin, infuse 800 units/hr
Available: heparin 40,000 units in 1000 mL D5W infusion pump
800 units/4000 units * (1000 mL) = 20 mL/hr
How many hrs will the IV run?
1000 mL / 20 mL/hr = 50 hrs
Mg/ hr Rule and Calculation
Pg 240
Order: calcium gluconate 2 g in 100 mL D5W; run 0.25 g/hr IV via infusion
pump.
100 mL
2g
=
x
0.25 g/hr
X= 13 mL/hr
Number of mL
mL/hr
100 mL
13 mL/hr
= 7.6 or approximately 8 hrs
Pg 243
Order: lidocaine 2 mg/min in IV
Supply: infusion pump, standard solution of 2 g in 500 mL D5W
(2000 mg in500 mL)
Multiply 2 mg/min × 60 = 120 mg/hr
500 mL
2000 mg
=
x
120 mg
X= 30 mL/hr
Number of mL
mL/hr
500 mL
30 mL/hr
= 16.6 or approximately 17 hrs
m2 Rule and Calculation
Page 251
Example
Patient: Height 6 feet 0 inches
Patient: Weight 175 lb, BSA 2.0 m2
Order: Platinol (cisplatin ) 160 mg ( 80 mg / m2 ) IV in 1 L NS with 2
mg magnesium sulfate over 2 hours
The rate of infusion is
1000 mL
_______
=
500 mL / hr
2 hr
Self – Test 4
Use of the Nomogram
2.
a)
b)
height 165 cm, wt: 70 kg BSA = 1.77 m 2
Order for Lomustine (CCNU) 230 mg po ( 130 mg / m 2 )
ONCE Q6 WEEKS
Is this dosage correct?
1.77 * 130 mg = 230.1 mg ( which is correct)
Lomustine comes in tabs of 100 mg and 10 mg. What is the
dose?
Administer 2 * 100 mg + 3 * 10 mg
Chapter 10 pg 280
Dosage Problems for Infants and Children
Dosage Based on mg/kg and Body Surface Area
EX: An infant weighs 20 lbs 12 oz. Convert the ounces to pounds.
Step 1. Because there are 16 oz in 1 lb, divide the 12 oz by 16.
12/16 = 0.75
Step 2. Add the answer to the pounds to get the total number of
pounds.
20 + 0.75 = 20.75 lbs
Self Test 1 pg 283
8. 12 lb 3 oz =
12 + (3/16) =12.19 lbs
12.19 lbs / 2.2 = 5.5 kg
Example pg 283
Mg/kg Body Weight
Augmentin (amoxicillin) 150 mg po q8h is ordered for a child weighing 33
lbs.
Accompanying prescribing information states that children  40 40 kg receive
6.7-13.3 mg/kg q8h.
We need to convert 33 lb to kg
Step 1. 33 lb / 2.2 kg = 15 kg
Step 2. Determine safe dose range in mg per kg.
Low Dose
High Dose
6.7 mg×15 kg =100.5 mg/kg
13.3 mg × 15 kg =200 mg/kg
Step 3. Is the dosage safe? Yes 
Step 4. Calculate the dose.
Label states 90 mL water should be added gradually to make a
concentration of 125 mg/ 5 mL.
X mL
_____
150 mg
=
5 mL
_____
125 mg
X= 6 mL
Example pg 288
A child weighing 50 lb is ordered Phenergan (promethazine) IM 20 mg for
nausea and vomiting. Is the dose safe? What amount should be given?
Step 1. Convert pounds to kg
50 lb / 2.2 kg = 22.727 kg
The child weighs 22.73 kg
Step 2.
Determine the safe dosage range. The Nursing Drug Guide states
1 mg/kg IM q4-6h prn. The safe dosage range is 10-25 mg.
Step 3. The ordered dose is 20 mg.
22.73 kg * 1 mg/kg = 22.73 mg
Hence, the dosage is safe!
Step 4. Calculate the dose.
X mL
1 mL
_____
=
_____
20 mg
25 mg
X= 0.8 mL (use 1 mL precision syringe)
Self Test 2 pg 290
2. Order: ferrous sulfate 200 mg po tid
Patient: child is 9 yrs old and weighs 30 kg
Supply: bottle of 125 mg/5 mL
Literature states: children 6 to 12 years old, 600 mg divided doses tid
Step 1. Observe patient’s weight in kg
Step 2. Check age range of child
6-12 yrs? Yes
Step 3. Proper range in present
Step 4.
X mL
5 mL
_____
=
_____
200 mg
125 mg
X= 8 mL po tid
8. Order: Cloxapen (cloxacillin) 250 mg po q6h
Patient: weighs 48 lbs
Supply: liquid labeled 125 mg/ 5 mL
Literature states for children more than 20 kg, the dose should
be 250 to 500 mg q6h.
Dosage is correct.
X mL
_____
250mg
=
5 mL
_____
125 mg
X= 10 mL
Steps and rule- m2 medication orders
Step 1. Find the BSA in m2
Step 2. Determine the safe dose using a reference.
Step 3. Decide whether the ordered dose is safe.
Step 4. Calculate the dose needed.
Self Test 4 pg 295
4. Child: 10 yrs; height 50 in; weight 35 kg
Order: Marinol (dronabinol) po 5 mg × 1
Literature: dose 5 mg / m2 1 to 3 hours before chemotherapy
Supply: 2.5 mg capsules
Step 1. Find the BSA in m2 = 1.1 m2
BSA= (127 cm * 35 kg / 3600) = 1.1 m2
Step 2. Determine the safe dose using a reference.
5 mg / m2 1 to 3 hours before chemotherapy
Step 3. Decide whether the ordered dose is safe.
5 mg/ 1.1 m2 = 4.55
Step 4. Calculate the dose needed. 2 capsules
Steps to solving parenteral pediatric medications IVP pg 297
Step 1. Convert lb to kg.
Step 2. Determine the safe dose range in mg/kg using a drug reference.
Step 3. Decide whether the ordered dose is safe by comparing the order with
the safe dosage range listed in the reference.
Step 4. Calculate the dose needed.
Step 5. Check the reference for diluent and duration for administration.
Example pg 297
Child: 5 yrs, 44 lb
Order: Tagamet (famotidine) 5 mg IV bid
Literature: 0.25 mg/kg q12h IV up to 40 mg/day
Dilute with 5 or 10 mL with 5% dextrose or 0.9% sodium chloride and
injected over at least 2 minutes.
Step 1.
44lb /2.2kg = 20 kg
Step 2.
20 kg × 0.25 mg/kg = 5 mg
Step 3. Decide whether the ordered dose is safe by comparing the order with
the safe dosage range listed in the reference.
Step 4. Calculate the dose needed.
Step 5. Check the reference for diluent and duration for administration