Download April 2012 - Grown Up - Calculating Flow Rates

Grown Up...
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A Newsletter For Those Who Care For
ADOLESCENTS, ADULTS, and AGING ADULTS
IV THERAPY… CALCULATING FLOW RATES
Volume 17, Issue 4
April 2012
Editor-in-Chief: Mary Myers Dunlap, MAEd, RN
BEHAVIORAL OBJECTIVES
AFTER
READING THIS NEWSLETTER THE
LEARNER WILL BE ABLE TO:
1. Calculate IV infusion flow rates.
2. Describe fluid compartments within the human body.
Maintaining a balance of fluid volumes and electrolyte
compositions in the fluid compartments is essential to health.
Fluid and electrolyte balance are closely interrelated. For
example, when bodily fluid volume increases,
as is often the case in congestive heart
failure, serum sodium levels may decrease,
causing hyponatremia. Major disturbances in
fluid and electrolyte balance can rapidly alter
cardiovascular, neurologic, and
neuromuscular functions. Administration of IV
fluids is the primary method of correcting fluid
and electrolyte imbalances. Intravenous fluid must be given
as ordered by the physician, the prescribed IV solution at a
specific rate, neither too fast, nor too slow.
Thanks to infusion pump technology, it may have been a
while since we have actually counted drops. Is it really
necessary to know how to calculate and count drops of an IV
infusion? Yes! What happens in a situation when the pump
fails and/or in an emergency situation when the IV tubing
has to be removed from the pump? What if you are in a
practice setting where infusion pumps are not available or
there are not enough available? What if there is an
emergency and the IV pump battery fails? Infusion pumps
can fail, as can all electronic equipment. All nurses need to
know how to calculate IV drip infusions.
Hanging a bag of IV fluid is considered administration of
a medication. Healthcare professionals must follow the
“rights” of medication administration – the right patient is
receiving the IV, the right drug (IV solution and/or additive) is
being infused, the right dose (the infusion time), the right
route (peripherally, centrally), and at the right time (500 ml
NS in 8 hours), as well as the right documentation and the
right reason. Be knowledgeable of the rate at which the IV is
infusing. When a burette or small-volume IV solution bag is
to be infused, without the use of an electronic device, the
flow rate in gtts/min will need to be calculated. When an IV
infusion pump is used, calculating the ml/hr is often required.
Healthcare professionals must know the drops per
minute to be infused, regardless of the device used. This is
good practice, and what the prudent nurse would do, which
is essential if a problem occurs and legal action is taken.
This newsletter will review calculation of IV flow rates. As an
introduction to types of IV solutions, which will be discussed
in an upcoming newsletter, fluid compartments will also be
discussed.
CALCULATING INFUSION RATES
The size of IV drops is regulated by the type of IV set
being used, which is calibrated in number of gtt/ml.
Unfortunately, not all sets (and their drop size) are the same.
Each hospital uses at least two sizes of infusion sets, the
standard, or macrodrip set, calibrated at 10, 15, or 20 gtt/ml,
which is used for routine adult IV administrations; and a mini,
or microdrip set, calibrated at 60 gtt/ml, which is used when
more exact measurements are needed, for example, to
infuse medications, or in critical care and pediatric infusions.
The gtt/m
calibration of
each IV set is
clearly printed
on each tubing
package. The first step in calculating flow rate is to identify
the drop factor,
the gtt/ml
calibration of the
set to be used for
infusion. The
order for the patient’s IV should include the type of IV
solution prescribed, as well as the infusion time. For
example, to hydrate a patient, the order is written as “LR 1
liter over 8 hours.” Therefore, 1 liter over 8 hours is the
infusion time. Remember that “keep vein open” (KVO) or
“wide open” are not appropriate orders because they do not
specify a rate of flow. The specific rate may be measured as
ml/hour or drops/min. To control or adjust the flow rate only
drops per minute are used.
To calculate the flow rate, one formula is as follows:
Volume (total) x Drop factor (gtts/ml) = Flow rate (gtts/min)
Time (in minutes)
1500 ml IV D5W is ordered over 12 hours
using regular tubing (15 gtts/ml). How many
drops per minute are needed to be delivered? Using the
formula above:
Example
1500 (total volume) x 15 gtts/ml = Flow rate (gtts/min)
720 (12 x60)
1500 x 15 = 22500 = 31.25 (31) gtts/min
720
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This formula is useful when small-volume flow rates are
used.
An IV medication of 100 ml is to be infused
Example
in 40 min using a set calibrated at 15 gtt/ml.
What is the flow rate?
1 liter of D5NS is to be infused at 30 ml per
hour. The IV set delivers 60 gtts/ml. What is
the correct rate of flow?
Example
30 (ml/hr) x 60 gtts/ml = 30 gtts/min
60
Calculate the gtts/min to be infused:
100 (total volume) x 15 gtts/ml = Flow rate (gtts/min)
40
100 x 15 = 1500 = 37.5 (38) gtts/min
40
The answer can also be obtained by using ratios and
proportions:
100 mL:40 min = X mL:1 min or 100 ml = X ml = 38 gtts/min
40 min 1 min
Let’s try a another calculation using tubing that delivers 10
gtt/ml.
The order reads: “Over the next 4 hours,
infuse 500 ml of D5W. Add 20 MEq of KCL
to solution.” The set is calibrated to deliver 20 gtt/ml. In
drops per minute, what is the flow rate?
Example
Volume (ml/hr) x Drop factor (gtts/ml) = Flow rate (gtts/min)
60
500 ml ÷ 12 (ml/hr) x 20 gtts/ml = Flow rate (gtts/min)
60
Let’s try a calculation using tubing that delivers 10 gtt/ml.
The order reads: “Over the next 4 hours,
Example
infuse 500 ml of D5W. Add 20 MEq of KCL
to solution. In drops per minute, what is the flow rate? Note:
In this example, the KCL adds minimal volume and doesn’t
need to be considered in your calculation of the flow rate.
Volume (total) x Drop factor (gtts/ml) = Flow rate (gtts/min)
Time (in minutes)
500 ml (volume) x 10 (gtts/ml) = Flow rate (gtts/min)
60 x 4 = 240 (minutes)
5000 = 20.8 (21) gtts/min
240
When an IV is ordered to infuse in more than 1 hour, this
formula can still be used. However, to keep the numbers you
are working with as small as possible, it is best to add a
preliminary step and determine the ml/hr the ordered volume
will represent. 60 will be the denominator, since there are 60
minutes in an hour.
Volume (ml/hr) x Drop factor (gtts/ml) = Flow rate (gtts/min)
60
1500 ml IV D5W is ordered over 12 hours
using regular tubing. How many drops per
minute are needed to be delivered?
Example
1500 ml ÷ 12 (ml/hr) x 15 gtts/ml = Flow rate (gtts/min)
60
125 x 15 = 125 = 31.25 (31) gtts/min
60
Let’s try a calculation using a mini-dropper (60 gtt/ml) with
this formula:
Volume (ml/hr) x Drop factor (gtts/ml) = Flow rate (gtts/min)
60
42 x 20 = 840 = 14 gtts/min
60
Regulating IV fluid is an ongoing process from the time
that an IV infusion is started until it is completed. Hourly
checks of an IV should include assessing and documenting
the IV flow rate, the IV site, the patient’s response to the IV,
how much fluid has infused, and how much fluid remains to
be infused.
FLUID COMPARTMENTS AND IV FLUIDS BASICS
Fluids within the body are contained in two basic
compartments - intracellular and extracellular. Intracellular
fluid (ICF) consists of fluid contained within all body cells and
is the larger of the two compartments. The extracellular fluid
(ECF) compartment contains all the fluids outside the cells.
The ECF is further divided into three areas - intravascular
fluid (fluid within the blood vessels), interstitial fluid (that
found in tissue spaces), and transcellular fluid (fluids
contained in body spaces), such as cerebrospinal fluid, the
pleural cavity, and joint spaces (synovial fluid).
Intravenous solutions are comprised of fluids (the
solvent) and particles (the solute) dissolved in the fluid.
Because the walls that separate fluid compartments are
porous, water moves freely between them. The tiny pores
that line the walls of the cells and capillaries also let small
solutes pass through easily. Changes in the level of solute
concentration, as occurs in various types of IV solutions,
influence the movement of fluid and electrolytes between the
fluid compartments.
An upcoming newsletter will discuss types of IV solutions with
related nursing implications, as well as assessment of fluid
overload and fluid deficit.
Growing Up With Us, Inc.
PO Box 481810 • Charlotte, NC • 28269
GUWU Testing Center
www.growingupwithus.com/quiztaker/
Phone: (919) 489-1238 Fax: (919) 321-0789
Editor-in-Chief: Mary M. Dunlap MAEd, RN
E-mail: [email protected]
Website: www.growingupwithus.com
Copyright © 2012 Growing Up With Us, Inc. All rights reserved.
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Name:_____________________________________________________
Date:___________________________________
Employee ID#:____________________________________________
Unit:____________________________________
POPULATION/AGE-SPECIFIC EDUCATION POST TEST
GROWN UP... Caring For Adolescents, Adults, and Aging Adults April 2012 Competency: Demonstrates Age-Specific Competency by correctly answering 9 out of
10 questions related to IV Therapy… Calculating Flow Rates.
IV THERAPY… CALCULATING FLOW RATES
1. Which fluid compartment contains cerebrospinal fluid?
a.
b.
c.
d.
intracellular
interstitial
transcellular
intravascular
2. Changes in the level of solute concentration, as occurs in various types of IV solutions, influence the
movement of fluid and electrolytes between the fluid compartments.
a. True
b. False
3. Identify the calibration in gtt/mL on this IV tubing package.
a.
b.
c.
d.
more information is needed.
60
70
1883
4. An IV of 150 mL is to infuse in 1 hr using a set calibrated at 60 gtt/mL. Calculate the gtt/min flow rate.
a.
b.
c.
d.
15
25
38
150
5. An IV of 1000 mL is ordered to infuse in 5 hrs using a set calibrated at 10 gtt/mL. How many gtts / min
should infuse?
a.
b.
c.
d.
8
33
83
200
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Name:_____________________________________________________ Date:___________________________________
POPULATION/AGE-SPECIFIC EDUCATION
POST TEST
Unit:____________________________________
Employee ID#:____________________________________________
GROWN UP... Caring For Adolescents, Adults, and Aging Adults IV THERAPY… CALCULATING FLOW RATES
6. Over the next 4 hours, 500 ml of D5W with 20 MEq KCL is to be infused using tubing that delivers 15
gtts/ml. In drops per minute, what is the flow rate?
a.
b.
c.
d.
20
31
38
125
7. An IV medication of 60 ml is ordered to infuse in 30 min. The set calibration is 20 gtt/mL. Calculate the
gtts/min flow rate.
a.
b.
c.
d.
3
20
30
40
8. A medication of 75 mL is to be administered in 50 min using a set calibrated at 10 gtt/mL. How many
gtts /min will infuse?
a.
b.
c.
d.
13
15
30
38
9. An IV order written as “KVO” as well as, “wide open”, doesn’t specify the flow rate and should,
therefore, not be carried out until there is clarification of the specific flow rate from the ordering
physician.
a. True
b. False
10. The prudent healthcare professional does not need to calculate the flow rate, in gtts/min, the patient is
receiving.
a. True
b. False
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