Fluid Therapy Lecture Review

Flashcards covering fluid imbalances, distribution, types of solutions, administration routes, volume calculations, monitoring, and specific crystalloid solutions for veterinary fluid therapy.

Total Body Water (TBW)

Water accounts for 60-70% of body weight, distributed into Intracellular Fluid (ICF, 67%) and Extracellular Fluid (ECF, 33%).

Extracellular Fluid (ECF)

Accounts for 33% of Total Body Water, further divided into intravascular (25%) and interstitial (75%) spaces.

Intracellular Fluid (ICF)

Accounts for 67% of Total Body Water. The membrane separating ECF and ICF does not allow passive movement of electrolytes.

Isotonic Crystalloid Solutions

Solutions (e.g., 0.9% NaCl, LRS, PlasmaLyte) with the same osmolarity as ECF. Administered electrolytes and H2O remain in the ECF, with 25% staying intravascular and 75% redistributing to the interstitial space.

Hypotonic Crystalloid Solutions

Solutions (e.g., 0.45% NaCl, D5W) with lower osmolarity than ECF. They distribute into both ECF and ICF, having little effect on intravascular volume maintenance. Used for hypoglycemia, electrolyte abnormalities, and chronic dehydration.

Hypertonic Crystalloid Solutions

Solutions (e.g., 7.5% NaCl) with higher osmolarity than ECF, pulling fluid from interstitial space and ICF into the vascular space, increasing total blood volume. Contraindicated in dehydrated patients.

Colloid Solutions

Solutions (e.g., HES, Blood, Plasma) containing large molecular substances that do not readily cross capillary membranes, remaining in the vascular space longer than crystalloids and drawing water into the intravascular space due to oncotic properties.

Perfusion Problem (Shock)

A fluid deficit in the intravascular space, characterized by tachycardia, poor pulse quality, prolonged CRT, pale MM, hypothermia, cold extremities, and hypotension.

Hydration Problem (Dehydration)

A fluid deficit in the interstitial space or ICF, characterized by tacky MM, decreased skin turgor, sunken eyes, and tachycardia.

Oral Route of Fluid Administration

Safest route for anorexia, mild dehydration, and diarrhea without vomiting. Contraindicated with vomiting, esophageal disease, or shock.

Subcutaneous Route of Fluid Administration

Used for mild dehydration and vomiting, but contraindicated for moderate to severe dehydration or shock. Only isotonic non-dextrose containing fluids should be used, no more than 10-20 ml/kg per site.

Intraosseous Route of Fluid Administration

Administering fluids via the bone marrow cavity, useful in emergencies as many fluids, blood, and drugs can be given, and the bone marrow does not collapse in hypotension and shock.

Intravenous Route of Fluid Administration

Used for mild to severe dehydration, hypotension, shock, and ongoing fluid losses (V/D, PU, fever).

Emergency Phase of Fluid Therapy

The initial phase for patients with clinical signs of shock, focusing on rapid administration of fluids to restore intravascular volume and treat life-threatening organ compromise.

Shock Dose of Isotonic Crystalloids (Canine)

90 ml/kg/hr for dogs, administered in smaller quarterly volumes with frequent reassessment until shock resolves.

Shock Dose of Isotonic Crystalloids (Feline)

45 ml/kg/hr for cats, administered in smaller quarterly volumes with frequent reassessment until shock resolves.

Rehydration Phase of Fluid Therapy

Aims to return hydration status to normal (deficit volume), replace normal ongoing needs (maintenance volume), and replace continuing abnormal losses (ongoing losses volume).

Deficit Volume Calculation

Estimated dehydration (%) multiplied by body weight (kg) multiplied by 1000 (0.07 x BW in kg x 1000 ml).

Maintenance Volume (Current Method, Dogs)

132 x BW (kg)^0.75/day.

Maintenance Volume (Current Method, Cats)

80 x BW (kg)^0.75/day.

Ongoing Losses Volume

Fluid loss due to conditions like PU, fever, wound drainage, or body compartment drainage. Quantified by estimating and doubling fluid loss for V/D, or increasing maintenance fluid volume by 10% for each 2°F increase in body temperature.

Maintenance Phase of Fluid Therapy

Generally begins no sooner than 24 hours after fluid therapy started, providing both maintenance and ongoing loss volumes after shock and deficit volumes have been addressed.

Central Venous Pressure (CVP)

Measures the ability of the right heart to accommodate presented fluid. Normal CVP is 0-5 cm H2O. Volume loaded is 8-10 cm H2O. Fluid overload is >10 cm H2O.

Replacement Crystalloid Solutions

Isotonic solutions (0.9% NaCl, LRS, PlasmaLyte) with higher sodium and chloride, lower potassium. Used in shock treatment.

Maintenance Crystalloid Solutions

Isotonic, hypotonic, or mildly hypertonic solutions (e.g., 0.45% NaCl + KCl, 0.45% NaCl with 2.5% Dextrose + KCl) with lower sodium/chloride and higher potassium. Contraindicated in shock treatment.

Physiologic Saline (0.9% NaCl)

An isotonic crystalloid solution indicated for shock, dehydration, hypoadrenocorticism, hyperkalemia, hypercalcemia, hypermagnesemia, hyponatremia, and metabolic alkalosis. Contraindicated in hypernatremia, cardiac disease, liver disease, and metabolic acidosis.

PlasmaLyte

An isotonic crystalloid solution indicated for shock, dehydration, liver disease, hypomagnesemia, and metabolic acidosis. Contraindicated in metabolic alkalosis and hypermagnesemia.

Lactated Ringer's Solution (LRS)

An isotonic crystalloid solution indicated for shock, dehydration, hypocalcemia, and metabolic acidosis. Contraindicated in liver disease, neoplasia, hypercalcemia, and metabolic alkalosis.

Half-strength Saline (0.45% NaCl)

A hypotonic crystalloid solution indicated for hypernatremia, ICF dehydration, cardiac disease, liver disease, and renal disease. Contraindicated in shock and hyponatremia.