1. Fundamentals of Pharmacology for Veterinary Technicians
Chapter 19
Fluid Therapy and Emergency Drugs
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Basics of Body Fluid
Water is the primary body fluid
Body water is distributed among three types of compartments: intracellular, intravascular, and interstitial
Intracellular fluid (ICF) = fluid within the cell (two-thirds of body water)
Extracellular fluid (ECF) = fluid within the blood vessels and in the tissue spaces between the blood vessels and cells (one-third of body fluid)
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Basics of Body Fluid
Body water contains solutes (substances that dissolve in solvent; particles)
Electrolytes are substances that split into ions when placed in water
Primary ions in the body are sodium, potassium, chloride, phosphate, and bicarbonate
Cations are positively charged ions
Anions are negatively charged ions
Body water is the solvent in biological systems
To establish equilibrium, body water moves along its concentration gradient
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Basics of Body Fluid
Extracellular fluid shifts between the intravascular space (blood vessels) and the interstitial space (tissues) to maintain a fluid balance with the ECF compartment
Fluid exchange occurs only across the capillary walls
Fluid therapy in animals may involve the use of crystalloids and/or colloids
Crystalloids are diffusible substances that dissolve in solution
Colloids are nondiffusible substances
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Fluid Therapy
The basis for fluid therapy depends on the animal’s hydration status (see Table 19-1)
Fluid therapy can replace water, sodium, potassium, and chloride electrolytes, and restore hydrogen ion balance (pH balance)
© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

6. Routes of Fluid Administration
Route of administration
Advantages
Disadvantages
Oral
Safest route
Easy
Less rapid absorption
Possible aspiration
Cannot use for vomiting animals
Subcutaneous
Relatively easy to administer
Absorption distributed over time
Possible infection
Must use isotonic fluids
Slower absorption
© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

7. Routes of Fluid Administration
Route of administration
Advantages
Disadvantages
Intravenous
Precise amount given is available rapidly
Various tonicities of fluid can be used
Possible fluid overload and vessel damage
Requires close monitoring
Must be sterile
Intraperitoneal
Relatively rapid absorption
Can be used when IV access is not available
Possible infection
Cannot use hypertonic solutions
Abdominal surgery hindered after administration
© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

8. Routes of Fluid Administration
Route of administration
Advantages
Disadvantages
Intraosseous
Useful for small animals, birds, and pocket pets
Can be used when vein inaccessible
Rapid absorption
Lack of confidence in administering fluid via this route
Possible infection
Rectally
Good absorption
Not frequently used
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Tonicity of Fluids
Tonicity refers to the osmotic pressure of a solution based on the number of particles per kilogram of solution (osmolality)
An isotonic solution has the same osmotic pressure as blood and extracellular water
A hypotonic solution has osmolality lower than that of blood; RBCs can swell
A hypertonic solution has osmolality higher than that of blood; RBCs can shrink
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Types of Crystalloids
Isotonic
0.9% sodium chloride (normal saline)
Lactated Ringer’s solution
Normosol
Plasmalyte
Hypotonic
5% dextrose in water (D5W)
¼ NS (0.25% normal saline)
½ NS (0.45% normal saline)
Hypertonic
0.9% normal saline with 5% dextrose
10% dextrose in water
3% normal saline
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Types of Colloids
Colloid solutions are fluids with large molecules that enhance the oncotic force of blood, causing fluid to move from the interstitial and intracellular spaces into the vascular space
Natural
Plasma
Albumin
Whole blood
Synthetic
Dextrans
Hydroxyethyl starch
Oxypolygelatin
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Fluid Additives
Special additives can be supplemented to crystalloid solutions
When administering additives, it is important to remember to withdraw and discard an amount of fluid equal to the amount of additive being supplemented
Types of additives:
50% dextrose
Potassium
Sodium bicarbonate
Calcium
Vitamins
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13. Calculating Fluid Volumes
Must consider that animals require fluids for the following:
Rehydration
Maintenance
Ongoing fluid loss
Make sure the units of measure are the same when performing these calculations
Make sure the volumes make sense; we don’t give 1,000 liters to a 4-pound cat
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14. Calculating Fluid Volume
Example: An adult 14-lb cat with 3% dehydration comes into the clinic. It is estimated that the cat vomited 100 ml of fluid overnight
Maintenance fluid is the volume of fluid needed daily to maintain body function
Maintenance fluids can be dosed at 50 ml/kg/day in adults and 110 ml/kg/day in young animals
Step 1: Convert 14 lb to kg using the conversion factor 2.2 lb = 1 kg
14 lb x 2.2 lb/kg = 6.4 kg
Step 2: Calculate maintenance volume
6.4 kg x 50 ml/kg/day = 318 ml per day
© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

15. Calculating Fluid Volume
Example: An adult 14-lb cat with 3% dehydration comes into the clinic. It is estimated that the cat vomited 100 ml of fluid overnight
Rehydration fluid is based on the estimated percent of dehydration
% dehydration x weight in kg = deficit in liters
Step 1: Convert 14 lb to kg using the conversion factor 2.2 lb = 1 kg
14 lb x 2.2 lb/kg = 6.4 kg
Step 2: Calculate replacement for dehydration
3% = 0.03
0.03 x 6.4 kg = l
0.192 l x 1,000 ml/l = 192 ml
192 ml x 0.8 (80% of dehydration value replaced in 24 hours) = 154 ml to replace on first day
© 2004 by Thomson Delmar Learning, a part of the Thomson Corporation.

16. Calculating Fluid Volume
Example: An adult 14-lb cat with 3% dehydration comes into the clinic. It is estimated that the cat vomited 100 ml of fluid overnight
Ongoing fluid loss is an estimation based on the additional loss of fluid due to vomiting or diarrhea
Take estimated volume
Step 1: Take estimated volume lost in fluid and add to the other volumes
Final step: Take all values and add together
318 ml ml ml = 572 ml
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17. How and How Quickly Is It Given?
Rate of fluid replacement parallels the severity of dehydration
Ideally, fluids are given over a 24-hour period
Fluids are stored and given by fluid bags or bottles attached to administration sets
Fluids are administered with either:
An adult administration set that delivers 15 gtt/ml (usually)
A pediatric administration set that delivers 60 gtt/ml (usually)
See text and “Fluid & Electrolytes for Veterinary Technicians” CD for sample calculations
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Emergency Drugs
In an emergency situation, it is important to remember basic life support
A = airway = establish a patent airway (endotracheal tube, suctioning, tracheostomy)
B = breathing = provide oxygen to the patient by providing airway or mechanical ventilation
C = circulation = get blood moving, either by manual manipulation of the heart or by the use of drugs
See Table 19-3
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