Fluid Therapy

Primary use of Fluid Therapy

Used to correct fluid deficits, electrolyte disturbances, and acid-base imbalances

How much of the body is composed of water?

60%

Total body water (TBW)

amount of water within the body (both intracellular and extracellular)

Intracellular fluid (ICF)

fluid within cells

How much of the TBW is intracellular fluids?

2/3

Intracellular fluid electrolytes

potassium, mangeisum, phosphorous

Extracellular fluid (ECF)

fluid outside cells

How much of the TBW is extracellular fluid?

1/3

Interstitial fluid

fluid in the spaces between cells (75% of ECF)

Intravascular fluid

fluid within blood vessels (25 % of ECF)

Extracellular fluid electrolytes

Sodium, chloride, and bicarbonate

Third space fluid

fluids can accumulate in the abdomen, pleural cavity, or extremities; abnormal water distribution

Electrolytes

active chemicals/elements that contain a charge; help with normal cell function

Most abundant extracellular electrolyte

Sodium

Most abundant intracellular electrolyte

Potassium

Hyponatremia

Low sodium; creates low osmolality, water will move into cells

Signs of hyponatermia

neurologic conditions, muscle weakness, lethargy, hypotension

Hypernatermia

high sodium; seen with severe dehydration, water leaves the cell

Signs of hypernatermia

neurologic conditions, excessive thirst, muscle weakness, seizures, possibly death

Hypokalemia

Low potassium

Hypokalemia causes

Decreased intake, excessive loss; movement from ECF to ICF

Hyperkalemia

high potassium

Hyperkalemia cause

Decreased excretion; compromises heart function; example: urinary obstruction

Acid-Base Balance

the regulation of the hydrogen ions in body fluid

Factors affecting acid-base balance

blood buffers, lungs, kidneys

Normal pH of venous blood

7

Normal pH of arterial blood

7

How is need for fluid therapy determined?

PCV/TS, USG, weight, eyes, skin turgor, MM color, CRT, HR, pulse strength and character

<5% dehydration

not clinically detectable

5%-6% dehydration

Subtle loss of skin elasticity

6%-8% dehydration

Obvious delay in return of tended skin to normal position; slightly prolonged CRT; eyes possible sunken in orbits; possibly dry mucous membranes

10%-12% dehydration

skin remains tented; very prolonged CRT; Possibly signs of shock

Signs of shock

tachycardia, cool extremities, rapid, weak pulse

12%-15% dehydration

obvious signs of shock, death imminent

Goals of fluid therapy

restore fluid losses, reestablish normal blood volume, improve tissue perfusion, facilitate administration of drugs

Crystalloids

substances in a solution that diffuse through a semipermeable membrane; most of the fluid is moved to the insterstitium

Replacement fluids

correcting deficits; crystalloid fluids

Maintenance fluids

maintaining hydration and electrolyte imbalances; crystalloid fluids

Balanced isotonic crystalloids

fluid similar to plasma; LRS, Norm-R/Isolyte/Phylyte/Plasmalyte, 0.9% NaCl, D5W

Unbalanced (hyper/hypotonic) crystalloids

not similar to plasma

Hypotonic crystalloid

0.45% NaCl

Hypertonic crystalloid

7.2% NaCl

Colloids

larger molecules that do not readily pass through semipermeable membranes; most of the solution stays in the intravascular space; more effective at expanding blood volume; use along crystalloids

Colloids can worsen ______________

coagulopathies

3 main types of Colloids

hydroxyethyl starches, dextrans, and gelatins

Dehydration

loss of total body water, no change to vascular volume; must be corrected slowly

Hypovolemia

loss of vascular volume, affects cardiac output; must be corrected very quickly to preserve life

Why would fluid therapy be required in a case of hemorrhage?

Correct hypovolemia

What type of fluid therapy might be used for hemorrhage?

Crystalloids +/- Colloids (blood transfusion)

Types of shock

hypovolemic, burn, cardiogenic, endotoxic, distributive

Purpose of fluid therapy in cases of shock

Improve blood pressure and restore perfusion

Diuresis

increased excretion of urine, "flushing" out toxins

What variables should be considered when estimating fluid losses?

-Volume of fluid needed to correct dehydration

-Volume of fluid for maintenance requirements

-Volume of fluid to correct for ongoing loses

Examples of ongoing losses

vomiting, diarrhea, blood loss, burns

Canine fluid maintenance dose

50-60 mL/kg/day

Feline maintenance fluid therapy

40-60 mL/kg/day

Hydration deficit

body weight (kg) x %dehydration x 1000= mL fluid deficit

Maintenance fluids calculation

(40-60 mL/kg) x kg= ml of daily fluid requirement

Ongoing losses calculation

Ongoing losses in mL/time in hours- mL/hr

Use of IV fluid bolus

rapid rescusitation

Preferred fluid administration route

PO

What type of fluids should be used for subcutaneous fluids?

Isotonic fluids

Contraindications for SC fluids

severe/debilitated; never give dextrose solutions >2.5% SQ

Contraindications for PO fluids

vomiting, severe life-threatening fluid imbalances requiring immediate correction

Indications for IV fluid administration

severely compromised patient

What bones can be used for intraosseous fluid administration?

Femur, humerus, wing of ilium

Complication of intraosseous fluid administration

Osteomyelitis

Fluid overload cause

excessive total volume or excessive rate of fluids

Monitoring for fluid overload

auscultate for evidence of pulmonary edema, central venous pressure, excessive weight gain, ins/outs

Signs of fluid overload

restlessness, tachypnea, serous nasal discharge, chemosis, pitting edema

Hyperpnea

increased respiratory rate

Chemosis

edema of the conjunctiva

Serous

watery