Transcript Solute - Macomb

RSPT 1060
MODULE C
Lesson 6
Solutions, Concentrations, &
Medication Delivery
OBJECTIVES
At the end of this module, the student will be able to…
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Define terms associated with solutions, concentrations
and medication delivery.
Describe the relationship between matter and mixtures.
Differentiate between a homogeneous and
heterogeneous solution.
Give an example of a colloid, suspension and solution
found in the human body.
Identify the components of a solution.
Give an example of each of the following solutions:
Gas dissolving in a liquid.
Solid dissolving in a liquid.
List the things that affect solids or liquids dissolving in a
liquid.
OBJECTIVES
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At the end of this module, the student will be able to…
List the things that affect gases dissolving in a liquid.
Differentiate between a dilute, saturated and a
supersaturated solution and a precipitate.
Differentiate between osmosis and diffusion.
Explain osmotic pressure and give examples of how it
works
Describe the different forms of tonicity
Explain the effects of a hypertonic, hypotonic and
isotonic solution as it is injected into the blood stream
Explain the effects of a hypertonic, hypotonic and
isotonic solution as it is inhaled into the
tracheobronchial tree.
Explain the reason for performing drug calculations in
respiratory therapy.
OBJECTIVES
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At the end of this module, the student will be able to…
Given a bottle of medication, identify the concentration of the
drug
Convert a ratio (dilution) solution and a % solution to mg/mL
Perform drug calculations given %weight/volume solutions (%)
Perform drug calculations given ratio solutions (1:100)
Perform calculations using the Universal Formula for solving
w/v solutions
Calculate drug dilution problems
Given a medication and a physician order, calculate the dosage
or volume required to deliver the ordered amount of
medication
Differentiate between Young's Rule, Clarks Rule, Fried's Rule
and Body Surface Area for calculating pediatric dosages.
Given an adult dose of medication, use an infant's age in
months, child's age in years, weight or body surface area to
determine the correct dosage.
WEB SITES
http://www.school-forchampions.com/science/chemixtures.htm
http://www.psinvention.com/mixtures.ht
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http://en.wikipedia.org/wiki/Mixture
http://en.wikipedia.org/wiki/Molal
http://el.hct.ac.ae/HSci/Pharm/Drugs.ht
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Mixtures
MATTER
Pure Substance
(homogeneous)
elements
compounds
Mixture
(heterogeneous or homogeneous)
colloids suspension solutions
Heterogeneous mixtures
Heterogeneous – colloid & suspension
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Not uniform
Large particles
Concentrations vary throughout
May settle
Can be easily separated by physical means
(filtration)
Homogeneous mixtures
Homogeneous – solution
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Usually transparent
Small (invisible) particles
Will not settle
Uniform concentration throughout
Can be separated by physical means
but not easily. (evaporation)
Mixtures
Three types:
– Colloids
– Suspensions
– Solutions
MIXTURES - Colloid
Examples: Cellular protoplasm, milk,
fat in blood, proteins in blood (albumin)
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Heterogeneous
Large molecules
Attract and hold water
Usually uniformly dispersed
Usually do not settle
Suspended in a gel
MIXTURES - Suspension
Examples: red blood cells in plasma
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Heterogeneous
Large particles that float in the liquid
Dispersed by agitation
Will settle if agitation stops
MIXTURES - Solution
Example: Saline (salt + water), medications,
electrolytes in body fluids
– Homogeneous
– Solute evenly dispersed throughout solvent so
concentration is same throughout
• Solute – smaller quantity dissolved, can be solid, liquid
or gas, “active ingredient”.
• Solvent – larger quantity, where solute is dissolved.
– “Aqueous” solution has water as the solvent.
Solutions - Gases in liquids
Ability of a gas to dissolve in a liquid
depends upon :
– Henry’s Law – dissolving (into)
– Graham’s Law – diffusion (through)
– Fick’s Law - overall relationships
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Surface area
Thickness
Partial pressure
Diffusion coefficient
Solutions - Solids & liquids in liquids
Ability of a solute to dissolve in a
solvent also depends upon:
– Physical properties of solute & solvent
(density, solubility coefficient)
– Pressure of solute
– Temperature of solute & solvent
– Presence of other solutes
Concentrations of solutions
– More or less solute or solvent will change the
overall concentration of the solution.
• Dilute – small amount of solute in solvent
• Saturated – maximum amount of solute in solvent
• Precipitate – Excess solute in solvent where some
solute settles out at bottom of solvent.
– As the concentration changes, the properties
of the solution change (freezing point, boiling
point…)
• Examples: salt on roads, anti-freeze in radiator
Concentrations of solutions
(A) Dilute solution
with relatively
few solute
particles.
(B)Saturated
solution where
the solvent
contains all the
solute it can
hold in the
presence of
excess solute.
(C) Supersaturation solution - Heating
the solution dissolves more solute
particles.
Concentrations of Medications
Concentration can be expressed as:
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%weight/volume (g/mL) – solids in liquid (meds)
%vol/vol (mL/mL) – both liquids
%solution
Ratio (weight:volume or g:mL) (meds)
Molal solution
Molar solution
Parts per million or parts per billion (extremely
dilute)
Medications (drug solutions)
Medications are solutes in solvents.
Calculations help quantify amounts of drug
(solute) in sterile water or saline (solvent).
Calculations also help express different
concentrations:
– %weight/volume (g/mL) – solids in liquid (meds)
– Ratio (weight:volume or g:mL) (meds)
– Parts per million or parts per billion (extremely
dilute)
Respiratory Therapy
Medications
Preparations:
– Multi dose – need to be measured and
diluted
– Unit dose – already diluted and ready to
use
Ultimate Goal of calculating is to
know how many cc or mL to
administer.
Treatment Demonstration
Nebulization of medication
– Solute = medication
– Solvent = saline or water
Order: 2.5 mg Albuterol in 2.0 mL N/S by
hand held nebulizer Q4 hours.
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Medication
Drug dosage
Diluent
Method of delivery
Frequency
How many mL of drug do we
need?
Two Ways to Determine:
1. Dosage on hand = Dosage desired
Volume on hand
Volume desired
DH = DD
* Called a weight-volume problem
VH
VD
*Need to have drug in mg/mL format
2. Universal Drug Calculation:
#cc x #% x 10 = #mg *Need to know drug %
Weight/Volume Method
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Used if we have the medication in
a vial that tells us how much of
the drug we have in solution.
Expressed as the amount of solid
dissolved in a liquid.
“g/mL”
Weight/Volume Solutions
Weight/volume solutions are ALWAYS expressed as
a % where the percent represents the number of
grams of drug in 100ml of solvent.
– 0.5% Solution = 0.5 grams per 100 mL
– 2.25% Solution = 2.25 grams per 100 mL
In order for us to use this, we must convert the
g/100 mL to mg/mL
– 0.5% = 0.5 grams per 100 mL OR 500 mg per 100 mL
– 2.25% = 2.25 grams per 100 mL OR 2,250 mg per 100 mL
Convert % to mg/mL
1% = ____g / _____ mL
= _____mg / _____ mL
0.4% = ____g / _____ mL
= ____mg / _____mL
0.25% = ____g / ____mL
= _____mg / _____mL
Medication Problems
Respiratory Therapy
Medications
Preparations:
– Multi dose – need to be measured and
diluted
– Unit dose – already diluted and ready to
use
Ultimate Goal of calculating is to
know how many cc or mL to
administer.
Treatment Demonstration
Nebulization of medication
– Solute = medication
– Solvent = saline or water
Order: 2.5 mg Albuterol in 2.0 mL N/S by
hand held nebulizer Q4 hours.
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Medication
Drug dosage
Diluent
Method of delivery
Frequency
Medication Example
The physician order states that you are
to administer 2.5 mg of albuterol. You
have a 0.5% albuterol solution. How
much medication (in mL) should you
draw up?
How many milligrams are in a 0.5% solution?
Medication Example Continued
DH = DD
VH
VD
500 mg = 2.5 mg
100 mL
x mL
By cross-multiplying:
Universal Drug Calculation
If you know the % of the solution,
you can use the Universal Drug
Calculation:
#cc x #% x 10 = #mg
Medication Example
The physician order states that you are to
administer 2.5 mg of albuterol. You have a 0.5%
albuterol solution. How much medication (in mL)
should you draw up?
#cc x #% x 10 = #mg
Practice
Sibberson’s Practical Math For
Respiratory Care: Chapter #6, Sample
Problems Second Set, page 72.
May skip step in Sample Problem First
Set.
Medication Order
Isuprel 5 mg of a 1:100 mL solution
in 2mL normal saline by small volume
nebulizer Q4 hours.
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Medication
Drug dosage
Diluent
Method of delivery
Frequency
Ratio Solutions
In this scenario, you are given the
concentration of the medication not
as a percentage, but rather as a ratio.
The ratio is expressing the
concentration as a weight/volume
relationship.
One Gram in some amount of mL of
solution
Ratio Solutions
Ratio solutions = 1 gram/??? mL
– 1:100 = 1 gram per 100 mL
– 1:200 = 1 gram per 200 mL
Convert to mg/mL
– 1:100 = 1000 mg per 100 mL
– 1:200 = 1000 mg per 200 mL
Convert to mg/mL
1: 200 = ____g / _____ mL = ____g / 100 mL = ____%
= _____mg / _____ mL
1:1000 = ____g / _____ mL= ____g / 100 mL = ____%
= ____ mg / _____mL
1:400 = ____g / ____mL = ____ g / 100 mL = ____%
= _____mg / _____mL
Ratios are always ____g / ______mL
Medication Example
The physician orders 5 mg of Isuprel.
You have a 1:100 solution. Determine
how much medication (in mL) to give.
What concentration of drug do you have?
– 1:100…What does that mean?
Medication Example
DH = DD
1000 mg = 5 mg
VH
100 mL
VD
x
Universal Drug Calculation
Need to convert the ratio to a
percentage.
1:100 = 1/100 = .01 = .01 * 100% = 1%
Universal Drug Calculation
The physician orders 5 mg of Isuprel. You have a 1:100
solution. Determine how much medication to give (#mL).
1:100 = 1% solution
Practice
Sibberson’s Practical Math For
Respiratory Care: Chapter #6, Sample
Problems Fourth Set, page 72.
May skip step in Sample Problem Third
Set.
Pressures in solutions
Solutes in solvents exert a pressure
Two kinds of pressure gradients exist:
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Diffusion
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The passive movement from an area of high
concentration to one of lower concentration
Osmotic
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The movement of water from an area of low
concentration to an area of high concentration.
Diffusion
Solute pushing across a semi-permeable
membrane
– Solute can move across membrane
The movement will continue until there
is an equilibrium in concentrations.
Osmotic pressure
Solvent (usually water) moving across a
semi-permeable membrane
– Solute cannot move across membrane.
The movement will continue until there is
an equilibrium in concentrations.
Solvent
movement is
indicated by
arrows
through the
membranes.
Osmotic pressure
Pressure that exists in the body because
of a solvent moving across a semipermeable membrane.
– Solute cannot move across membrane.
Solution
0.9%
Cell
0.5%
Cell shrinks
Solution
0.9%
Cell
0.5%
Water Movement
Attempting to have equal concentrations
on both sides of membrane.
Tonicity
Def: The amount of osmotic
pressure in a solution.
– Isotonic – having the same
concentration as that of the body fluids
(such as 0.9% “normal” saline)
– Hypertonic – higher concentration that
cause cells to shrink (crenation)
– Hypotonic – lower concentration that
cause cells to swell (hemolysis)
Hypertonic
Higher concentration that cause
cells to shrink (crenation)
IV 3% saline
Fluid moves from cells into vasculature
0.9%
0.9%
0.9%
3%
Cells shrink - crenation
Hypotonic
Lower concentration that cause
cells to swell (hemolysis)
IV 0.45% saline
Fluid moves into cells from vasculature
0.9%
0.9%
0.9%
0.45%
Cells swell - hemolysis
Changing concentrations
C 1 x V 1 = C2 x V 2
Use this calculation when the
concentration of a medication or
solution is too strong and needs to be
diluted.
NOTE: Adding more solvent
– Does not change the amount of solute
(amount of medication)
– Does decrease the concentration
– Does decrease tonicity & osmotic pressure
Dilution Example
If you have 10cc of 20% Mucomyst
and need a 10% solution, what do
you need to do?
Question: How many cc of saline
need to be added to 10 cc of 20%
Mucomyst to obtain 10%
Mucomyst?
Dilution
If you have 20cc of 0.9% normal
saline and need 0.3% saline, what do
you need to do?
Question: How many cc of sterile
water need to be added to 20 cc of
0.9% Saline to obtain 0.3% Saline?
Questions
When you add more solvent (water or saline) to a
medication will you be giving more medication
(solute)?
When you add more solvent (water or saline) to a
medication what will happen to the concentration
(tonicity)? (increase, decrease or stay the same)
When you add more solvent (water or saline) to a
medication what will happen to the time it takes to
aerosolize? (increase, decrease or stay the same)
Pediatric calculations
Body surface area (Dubois Chart)
– (Child BSA m2 / 1.73) x adult dosage
Fried’s Rule
– Infants < 1 year
– (Infant age in months / 150 months ) x adult dosage
Young’s Rule
– Child 1 – 12 years
– (Child’s age in years/age + 12) x adult dosage
Clark’s Rule
– (Child’s weight in pounds/150 pounds) x adult dosage
ASSIGNMENTS
Read:
– Egan Chapter 11 – pages 255 – 258 & 259 – 261
Sibberson’s Practical Math For
Respiratory Care:
– Chapter #6, Sample Problems & Practice
Exercises, pages 67 – 79.
Instructor assignments