Fluid Therapy and Fluid Calculations

Vocabulary flashcards covering key terms and concepts related to veterinary fluid therapy, anesthesia rates, dehydration assessment, fluid calculations, monitoring, and common fluid additives.

Fluid Therapy

The administration of fluids to correct dehydration, electrolyte or acid-base imbalances, deliver drugs, or maintain perfusion.

Dehydration

Loss of body water resulting in reduced circulating volume; corrected by calculated fluid replacement.

Electrolyte Abnormalities

Imbalances in ions such as Na⁺, K⁺, Cl⁻ that can be corrected with appropriate fluid therapy.

Acid-Base Abnormalities

Disturbances in blood pH (acidosis or alkalosis) managed with specific fluids or additives.

Constant-Rate Infusion (CRI)

Continuous delivery of drugs dissolved in fluids at a steady rate.

Diuresis

Increased urine production induced by fluids to support renal function or eliminate toxins.

Hypotension

Low blood pressure; primary reason for giving fluids during anesthesia.

Vasodilation

Widening of blood vessels that can cause hypotension and require fluid support.

Respiratory Acidosis

Acidosis caused by CO₂ retention during respiratory depression under anesthesia.

Metabolic Acidosis

Acidosis due to decreased cardiac output or certain anesthetic agents; fluids help correct it.

Anesthetic Fluid Rate – First Hour

10 ml/kg/hr of crystalloids recommended for the first hour under anesthesia.

Anesthetic Fluid Rate – Maintenance

5 ml/kg/hr after the first hour of anesthesia.

Blood Loss Replacement Rule

Add 3 ml of crystalloid for every 1 ml of blood lost during surgery.

Reduced Rate Exceptions

Geriatric, pediatric, cardiac, or respiratory-compromised patients receive 5 ml/kg/hr during anesthesia.

Packed Cell Volume (PCV)

Percentage of red blood cells in blood; elevated values can indicate dehydration.

Blood Urea Nitrogen (BUN)

Waste product measured in blood; increased levels may signal dehydration.

Skin Turgor

Elasticity of skin used to assess hydration status; loss causes skin tenting.

Skin Tenting

Prolonged elevation of pinched skin indicating fluid deficit.

Capillary Refill Time (CRT)

Time for gum color to return after blanching; prolonged (>3 s) suggests severe dehydration.

No visible clinical signs despite mild fluid loss.

5 % Dehydration

Mild dehydration characterized by tacky mucous membranes.

7 % Dehydration

Moderate dehydration with dry mucous membranes, mild skin tent, slight tachycardia, CRT 2–3 s.

10 % Dehydration

Severe dehydration with marked skin tent, sunken eyes, tachycardia, cold extremities, possible shock.

12 % Dehydration

Fluid loss accompanied by obvious shock and hypotension.

Fluid Deficit Formula

Body weight (kg) × % dehydration = liters of fluid deficit.

80 % Rehydration Rule

Replace only 80 % of calculated deficit within the first 24 h to avoid hemodilution.

Maintenance Fluid Requirement

Normal daily need, commonly 30 ml/lb or 44–66 ml/kg per day.

Sensible Losses

Fluid losses that can be measured (e.g., urine, vomitus).

Insensible Losses

Unmeasurable losses such as respiration and sweating.

On-Going Losses

Continuing fluid losses; estimate measured volume and double it, or add 4 ml/kg per episode.

Total Daily Fluid Needs

(80 % deficit) + maintenance + on-going losses.

Overhydration

Excessive fluid administration leading to edema, nasal discharge, or pulmonary crackles.

Chemosis

Edema of the conjunctiva, an early sign of fluid overload.

Potassium Chloride (KCl)

Common additive at 2 meq/ml used to treat hypokalemia in fluid bags.

Potassium Infusion Limit

Never exceed 0.5 meq/kg/hr to avoid cardiac arrest.

Safe KCl Rate Calculation

Three steps: (1) BW × 0.5 meq/kg/hr, (2) convert bag meq/L to meq/ml, (3) divide dose by concentration.

Sodium Bicarbonate

Alkalinizing additive for severe metabolic acidosis (e.g., ethylene glycol, diabetic ketoacidosis).

Calcium Precipitation Warning

Do not add sodium bicarbonate to calcium-containing fluids to prevent precipitate formation.

B-Complex Vitamins

Water-soluble vitamins commonly added (1–2 ml/L); turn the fluid bag yellow.

50 % Dextrose

Concentrated glucose source; diluted using C₁V₁ = C₂V₂ formula for hypoglycemia.

C₁V₁ = C₂V₂

Dilution equation used to prepare desired dextrose concentrations in fluids.

Additive Labeling

Immediately record the type and amount of all additives on the fluid bag to ensure safety.

Sodium bicarbonate

*Do not add to calcium-containing fluids or calcium precipitates will occur *

Potassium danger !

Rates higher than 0.5 meg/kg/hr will stop the heart