Chapter 8 Calculation of Basic IV Drip Rates
Microdrips
Macrodrips
Types of Intravenous Fluids
Sterile plastic bags
Sterile glass bottles
Careful to prepare our solutions
Avoid any errors – may result in patient electrolyte
imbalance
Written order – come from the physician
Label may be different
D -> Dextrose
W -> Water
NS -> Normal Saline (0.9% saline-> 0.9 g per 100 mL
water)
Written
Supply
1000 mL D5W
1000 mL D5%W
500 mL D5S
500 mL D5%0.9NS
250 mL D51/2NS 250 mL D5%0.45NS
500 mL D51/3NS 500 mL D5%0.33NS
500 mL NS
500 mL 0.9% NS
1000 mL 1/2 NS 1000 mL 0.45%NS
Kinds of IV Drip Factors
Check Infusion Set: See needle in the chamber: microdrip
Deliver to the patient 1mL fluid
60 drops = 60 gtt = 1mL
Infusion sets with no needle in the chamber – macrodrip
Baxter-Travenol macrodrip set to deliver 10gtt/mL
Abbott macrodrip set to deliver 15 gtt/mL
Tubing for the above sets can be clamped (opened or closed
to set the drip rate)
Infusion pumps – need only two pieces of info
1) total number of milliliters
2) number of milliliters per hour (infusion rate)
Can also do IVPB
Order: 500 mL D5W IV
Run: 50 mL/hour
Primary versus Secondary
IVPB
Ampicillin 2 g IVPB in 100mL NS over 1 hour
Labeling IVs
Label such that what drip rate is and what is being infused
into the patient
Patient
Date, Time
Order
Time
Room
Rate
Run
Initials
Katherine Papademas
10/02, 1300
1000 mL D5W1/2NS
1300 to 0100
436B
50gtt/min
50 mL/hr
DD
Note: 1000 mL
Run time: Finish time – start time = total hours IV runs
Calculating Basic IV Drip Rates
mL/hour
Step 1:
Total number of mLs ordered = no. mL/hr
Number of hours to run
Step 2:
Number of mLs/hr x Tubing Drip Factor (TF) = drops per minute (gtt/min)
Number of minutes
Order: 1000 mL Ringer’s Lactate IV 8am-8pm
Available: an infusion pump
Logic:
Run time: 12 hours
Step 1:
1000 mL/12 hours = 83.33
(round to nearest whole number)
Enter: total volume: 1000 mL
mL/hr: 83
Order: 500 mL D5NS IV 12noon-4pm
Available: microdrip at 60 gtt/mL;
Macrodrip at 20 gtt/mL
Logic
Run time: 4 hr
Step 1: #mL/hr = 500 mL/4hr = 125 mL/hr
Step 2: Macrodrip calculation
#mL/hr x TF
#min
= 125mL/hr x 20 gtt/mL = 41.6 gtt/min
60 min
= 42 gtt/min
1 hr = 60 min
Step 2: Microdrip calculation
#mL/hr x TF
#min
= 125mL/hr x 60 gtt/mL = 125 gtt/min
60 min
Which one should you choose?
Use Microdrip when …
IV administered over a long period of time
Small amount of fluid to be infused
Macrodrops per minute are too few
Use Macrodrip when …
Large amount of fluid is ordered in a short time
Microdrips per minute are too many and counting the
drip rate might be difficult for the nurse
Need for continuous observation
Check IV frequently
Gravity
Patient’s movements : kink the tube
Watch the flow of the fluid with respect to where
the needle has been inserted – check for infiltration
Swelling
Pain
Coolness
Pallor at the insertion site
Eg. Order: 500 mL D51/3NS IV KVO for 24◦
Available: microdrip at 60 gtt/mL; macrodrip 10gtt/mL
Will have to choose the IV set (as no infusion pump)
Step 1:
# mL/#hr = 500 mL/24 hr = 20.83 mL/hr = 21 mL/hr
Step 2: Macrodrip
#mL/#hr x TF = 21 mL/hr x 10 gtt/mL = 3.5 gtt/min
60 min
60 min
= 4 gtt/min
Step 2: Microdrip
#mL/#hr x TF =
60 min
21 mL/hr x 60gtt/mL =
60 min
21 gtt/min
Which do we choose?????
Macrodrip 4gtt/min too slow
Select microdrip infusion set
Set drip rate at 21 gtt/min
No. 4 on p. 203
Order: 180 mL D5 1/3NS 12 noon – 6pm
Available: macrodrip (10gtt/mL); microdrip (60 gtt/mL)
Step 1
180 mL/6 hr = 30 mL/hr
Step 2 Macrodrip
30mL/hr x 10gtt/ml = 5 gtt/min
60 min
Step 2 Microdrip
30 mL/hr x 60 gtt/mL =
60 min
30 gtt/min
Choose microdrip
Determining hours an IV runs
Number of mLs ordered = run time (#hrs to run)
Number of mLs/hr
Order: 500 mL NS IV; run 75 mL/hr
500 mL = 6.66hr -> 6.7 hr
75 mL/hr
Order: aminophylline 500 mg in 250 mL D5W IV at 50mL/hr
250mL
= 5 hr
50 mL/hr
Adding Medications to IV
When continuous IV order includes medication; add
medication to IV and determine rate of flow
Either pharmacist or nurse will add medication
Buretrol: IV delivery system with tubing and chamber (can
hold 150 mL delivered as microdrip)
Medications ordered over several Hours
Order: 1000 mL D5W with 20 mEq KCl IV 10am-10pm
Available: vial of KCl 40 mEq/20 mL, microdrip (60gtt/min),
macrodrip (20 gtt/min)
D xS=A
H
Desire: 20mEq
Have: 40mEq
Supply: 20 mL
a)
20mEq x 20mL = 10 mL (dosage amount)
40mEq
b) Calculate drip factor
Step 1: #mL/#hr = 1000 mL/12 hr = 83 mL/hr
Step2: Macrodrip
83 mL/hr x 20 gtt/mL = 28 gtt/min
60 min
Step 2: microdrip
83 mL/hr x 60 gtt/mL = 83 gtt/min
60 min
Class chose macrodrip
Add 10 mL KCl to the IV bag
Order: 5 milliunits penicillin G in 1000 mL D5W IV q8hr
Available: macrodrip (10 gtt/mL), microdrip (60gtt/mL)
Logic:
Milliunit -> million units
5 milliunits -> 5000000 units of Penicillin G potassium
Supply: 5-milliunits vial of powder
Directions: reconstitute with 100 mL
Order is safe
Use a 10-mL syringe to remove fluid aseptically from 1000mL bag D5W
Inject 10mL into vial containing powder – make sure all
liquid!!!!!!!
Inject the new supply into the bag (990 mL + 10 mL)
Now that medication has been added – calc the drip factors
and choose!!!!
Step 1: 1000mL/8hr = 125 mL/hr
Step 2:
Macro
125mL/hr x 10 gtt/mL = 20.83 gtt/min =21gtt/min
60 min
Micro
125mL/hr x 60gtt/mL = 125 gtt/min
60 min
p. 207-208
buretrol = microdrip
Order: aminophylline 250 mg in 250 mL D5W; run at 50
mL/hr
Available: ampule of aminophylline 1g in 10mL; Buretrol that
delivers 60 gtt/mL
Logic: Ampule – 1g /1000 mL = 1000 mg/1000 mL
(1) Use Formula Rule
250 mg x 10 mL =2.5 mL want to administer
1000 mg
(2) Preparation: draw up 2.5 mL of drug and inject it into
250 mL D5W. Label the bag.
Buretrol: microdrip 60 gtt/mL
(3) Determine drip rate
mL/hr x TF = 50 mL/hr x 60 gtt/min = 50 gtt/min
60 min
60 min
(4) Label IV Bag: Rate, 50 mL/hr
Eg. Self Test 3 – No. 3
Order: 250 mg hydrocortisone sodium succinate in 1000 mL
8AM – 12 midnight
Available: vial of hydrocortisone sodium succinate labeled
250 mg with a 2mL diluent; microdrip tubing
1) determined total time
8am – 12 midnight = 16 hours
2) determine #mL/hr = run time
1000 mL/16 hours = 62.5 mL/hr -> round to 63 mL/hr
3) #mL/hr x TF = 63 mL/hr x 60 gtt/min = 63 gtt/min
60 min
60 min
4) Label IV:
Medications for Intermittent Intravenous
Administration
IVPB
q4h, q6h, or q8h = time intervals
most in powder form
check dr’s order (drug, route, time interval)
nurse must research manufacturer’s directions for
amount and type of diluent and time for infusion to run
Rule to solve IVPB same as rule to solve IV
#mL x TF = gtt/min
#min
# mL = type and amount of diluent stated on label/insert
TF: tubing for IVPB-> called secondary administration set
and has a macrodrip factor. Shorter than main line IV tubing
– check label for Tubing drip factor
#min -> if number of min not given for IVPB, then general
rule: 30 minutes for every 50 mL solution for adults
Eg. Order: cefazolin 1 g IVPB q6h
Supply: package insert for IVPB dilution of cefazolin sodium:
Reconstitute with 50 to 100 mL sodium chloride injection or
other solution listed (D5W, D10W, D5LR, D5NS)
Use 50 mL D5W
As no time given: use 30 min for 50mL
#mL x TF = gtt/min
#min
50mL x 10 gtt/min = 16.6 = 17 gtt/min
30 min
Use reconstitution device (sterile implement containing 2
needles that connects vial and 50 mL bag)
Admixture IVs
If health care pharmacy reconstitutes and prepares IVPB in a
sterile environment using laminar flow hood – you as nurse
still need to check for proper labeling etc.
Check dose, check expiration date, etc.
Changing the Intravenous drip Rate
If kinking of tube, movement of patient, placement of
needle/catheter, gravity affect flow – then might have to
recalculate IV drip
Eg.
Label on IV: 1000 mL D5W IV to run 8am – 4pm
Tubing is macrodrip (10gtt/mL); rate set at 20gtt/min
Time now: 1pm
Amount of fluid you observe left in IV bag: 600 mL
Change drip?
Logic
Step 1: calculate #ml/hr
1000ml/8hr =125 mL/hr = delivery rate
Step 2: calculate how many hours have elapsed
5 hours have elapsed
125 mL/hr x 5 hr = 625 mL should have been delivered
Step 3: Make an educated decision
Step 3: As 600 mL left in IV, only 400 mL were delivered
(rather than the 625mL)
625 mL – 400 mL = 225 mL behind
Conclude: make judgment to increase IV drip rate – call the
doctor
Recording intake : keep accurate account of parenteral
intake as well as liquids taken orally/enterally (tube
feedings)!
Ex.
#8. p 213
IV of D5W 1000 mL infusing at 125 mL/hr
1000mL/125 mL/hr = 8 hr
#4
Order: 500 mL aminophylline 0.5g to infuse at 50 mL/hr.
How mg patient receive per hour
0.5 g = 500 mg
500 mg in 500 mL -> 1mg/mL (concentration of drug)
1mg/mL x 50 mL/hr - 50 mg per hour