Fluid therapy

What elements are most important in regulating electrolyte balance?

Sodium and potassium

Osmotic pressure

Pressure or force that develops when 2 solutions of different concentrations are separated by a selectively permeable membrane

Osmolality

Measures the number of dissolved particles, regardless of their size, per KG of water

Fluid Therapy Basics

Determined by:

• Pulse rate and quality

• CRT

• Moistness of MM

• Appearance of eyes

• Patient history (Vomiting or diarrhea)

• Skin tugor test

Rehydration fluids

Fluids given to correct fluid loss due to dehydration

Maintenance fluids

Fluids given to replace fluid lost daily via normal body functions

Replacement fluids

Fluids given to to replace fluid lost through vomiting and diarrhea, etc, given on top of other volumes

Crystalloids

Solutions of electrolytes/salts with or without glucose dissolved in water are commonly used to replace lost fluid and electrolytes

Isotonic crystalloids

Used to replace fluid loss. Similar composition to plasma; commonly used for hypovolemic shock

Isotonic crystalloids examples

• Isotonic Saline (0.9% sodium chloride)

• Lactated Ringer’s Solution (LRS)

• Normosol and Plasma-Lyte A or R

Hypotonic crystalloids

Fluids with less sodium concentration than ECF. Cause a portion of the fluid to move out of the intravascular space. Used in P’s with increased level of sodium that cannot tolerate solutions with sodium

Hypotonic crystalloids examples

• 5% dextrose in water

• 0.25% normal saline

• 0.45% normal saline

Hypertonic crystalloids

Have high sodium concentrations and cause water to rapidly move out of the cells and into the blood vessels. Used to tx shock and edema

Hypertonic crystalloids examples

• 0.9% normal saline with 5% dextrose

• 3% normal saline

Colloids

Solutions with large molecules that stay in the vessels longer. Cause fluids to pull water into the circulatory system. Used to tx hypovolemic shock and hypoproteinemia

Natural colloids

• Plasma

• Albumin

• Whole blood

Synthetic colloids

• Vetstartch

• Hetastartch (Hydroxyethyl starch)

• Dextran

Whole blood

Commonly used to tx severe anemia and severe blood loss

Plasma

Contains albumin and globulins. Can be stored frozen for long periods of time

Albumin

Main protein in the blood and constitutes about 50% of total blood proteins

Hydroxyethyl starch (Hetastach)

Synthetic colloid that expands plasma volume

Tetrastarches (Vetstarch

Safer hetastach but more expensive

Dextran

Synthetic colloid solution with large polysaccharides derived from sugar beets. Expands circulating blood volume within one hour and effects last for 24 hours or longer

Fluid bag labeling musts:

1. The patient's name. 

2. The date it was opened. 

3. Name and amount of any supplements/additives. 

4. The date and time fluid administration started. 

5. Flow Rate. 

6. Expiration date. 

7. Initials of the person preparing the fluids.

Adult administration set rate

15tt/mL

Pediatric administration set rate

60 gtt/mL

Calculating drip rates must knows:

• Which administration set you’re using

• Length of administration time (typically 24 hrs)

• Amount of fluid to be administered (in mL)

Fluid pumps

Fluid pumps compress the line as needed and monitor flow to provide the desired amount of fluid at the desired rate (in mL/hr)

VTBI

Volume to be infused (Total fluids given)

PRI

Primary rate of infusion (Rate at which fluids are given)

Fluid additives

Added to fluids for certain cases/patients

50% dextrrose

Carbohydrate used to correct hypoglycemia, anorexic patients with sepsis, patients with increased metabolic needs

Potassium

Necessary for the contraction of smooth, cardiac, and skeletal muscles for physiologic processes. Supplemented to anorexic patients, fluid losses from diuresis or diarrhea

Sodium bicarbonate

Plays a vital role in acid-base balance of the body, added to fluids to correct metabolic acidosis. Usually from diabetic acidosis, severe renal disease, prolonged cardiac arrest

Calcium

Necessary for the functioning of nerves and muscles, the clotting of blood, the building of bone and teeth, and other physiologic processes.

Vitamin B complex

Crucial for various bodily functions, including converting food into energy, forming red blood cells, and maintaining healthy nervous system function

What are four routes that fluids can be given? 

PO, SQ , IV, IO

What is the recommended maintenance fluid rate for dogs?

2 to 6 mL/kg/HR

What is the recommended maintenance fluid rate for cats and why is it different from dogs?

2 to 3 mL/kg/hr. Cats are less since they are more prone to fluid overload.

What are the 3 types of fluid volume loss we account for in practice?

Isotonic, Hypotonic, Hypertonic