Lecture 4 Flashcards
What to mean conditions is fluid therapy used for
Hypovolemic shock and dehydration
What is perfusion
The process in which blood carries oxygen and important nutrients to body tissues. Depends on many body compensatory responses but also on the administration of appropriate fluid volumes to maintain intravascular volume
What are six purposes of fluid therapy
Replace water loss, maintain normal hydration, restore electrolytes and nutrients, vehicle to administer IV medications, replenish blood loss, increase or maintain intravascular osmotic pressure
What percent of an animal’s total body weight is made up of water
60%
What percent of body weight is made up of water in neonate’s
80%
What are the three main components of total body water distribution
Intracellular fluid space. Interstitial fluid space. Intravascular fluid space.
What percent of total body water does intracellular fluid space make up
66%
What percent of total body water is interstitial fluid space make up
24%
What percent of total body water does intravascular fluid space make up
10%
What is considered extracellular fluid
Interstitial fluid space and intravascular fluid space
How much percent of total body water does extracellular fluid make up
34%
Describe intracellular fluid
Within cells
Describe interstitial fluid
Between cells
Describe intravascular fluid
Water within blood vessels and lymphatic system
What percent of body weight does the blood volume makeup in dogs
8 to 9% of body weight
What percent of body weight does blood volume make up in cats
6 to 7%.
What is the total body water in a healthy dog
534 to 660 mL per kilogram
What is the estimated intravascular water volume in dogs
90 mL per kilogram
What is the estimated intravascular water volume in cat
45 mL per kilogram
What separates extracellular and intracellular fluid
Cell membrane which is permeable to water but not to most solutes
What solutes does body water contain
Cations, anions and other solutes
What is responsible for generating concentration gradient across the membrane
The ion channels and the active solute pumps
What are the three normal inputs of H2O for an animal
Water, food, metabolism of carbohydrates and fat
What are the three things responsible for the loss of H2O in an animal
Peeing, pooping, sweating and hypersalivation
What is the estimated water loss over 24 hours from peeing
20ml/kg/24hr
What is the estimated water loss over 24hrs from pooping
10-20ml/kg/24hr
What is the estimated water loss over 24hrs from sweating and hyper salivating
20ml/kg/24hr
What is the total estimated loss per day on average
50-60ml/kg/24hr
What is the total estimated fluid loss for puppies/kittens in a day
80ml/kg/24hr
How do you calculate maintence
50-60ml/kg/day
What is osmotic pressure
The amount of pressure necessary to stop the flow of H2O across a semi permeable membrane
What is hydrostatic pressure.
It’s basically blood pressure. Pressure generated by the force of a fluid within a compartment
What is the colloid oncotic pressure
The power of intravascular protein to retain fluid within blood vessels. Opposite to hydrostatic pressure and pulls the fluid into the circulatory system
What is the capillary membrane composed of
Thin membrane of endothelial cells that contain tight or gap junctions through which fluid and Solutes can flow. Permeable to water and electrolytes but not to proteins
What are the two ways solutes dissolved in fluid can flow between compartments
By passive diffusion from an area of higher to lower concentration. Or From one compartment to another by active transport mechanism
What does the rate of fluid exchange depend on
The forces that favor fluid retention within compartments versus the forces that favor fluid movement or filtration from a compartment to another
How is the colloid oncotic pressure dictated
By the concentration of proteins within the space. Albumin mainly contributes to it. Proteins are large molecules so they remain within blood vessels, retaining fluid with them and thereby maintaining blood volume.
What happens when hydrostatic forces exceed oncotic colloid forces
Fluid will leave one compartment and go to the other
What determines how fluids are distributed during fluid therapy
The composition of the administered fluid, in conjunction with the hydrostatic pressure and the colloid oncotic pressure in the capillories and tissues
What does the movement of a particular fluid between compartments depend on
The permeability of the relevant barrier (capillary membrane versus cell membrane)
The concentration of molecules contained within each compartment
What will happen to intravenous fluid containing small molecules
It will pass freely out of the capillaries and into the intracellular space. They will be distributed throughout both the intravascular space on the interstitial space
What happens to intervenous solutions containing large molecules
They will remain within the capillaries. They will expand the intravascular space more efficiently
What will happen to intervous solution that is more concentrated than plasma
It will draw water into the blood vessels from the intracellular and interstitial spaces
What two factors cause a disordered fluid balance
Decreased intake or increased output
How is the degree of dehydration estimated
History, physical exam, laboratory tests
When taking the animals history and checking for dehydration what questions do you need to ask about
Route of loss, duration of loss, type of loss, frequency and volume of loss, concurrent medical problems
When doing the physical examination of the animal how do you estimate dehydration
Bodyweight, skin elasticity, pulse quality, mucous membrane color, temperature, attitude, heart rate and respiratory rate
What are acute losses of bodyweight considered
Mostly fluid losses
What does .1 kg of weight lost equal in fluid lost
100 mL of fluid
What an animal is less than 5% dehydrated what are the physical examination findings
History of fluid loss but no physical examination abnormalities
What an animal is 5% dehydrated what are the physical examination findings
Slight decreased skin turgor, semi dry oral mucous membranes
When in animal is 7% dehydrated what are the physical exam findings
Mild to moderate decreased skin turgor, dry oral mucous membranes, slight tachycardia, capillary refill time greater than or equal to three seconds
What an animal’s 10% dehydrated what are the physical exam findings
Moderate to marked decreased skin turgor, Dry oral mucous membranes, moderate signs of shock Pale mucous membranes, tachycardia, capillary refill time greater than three seconds, decreased pulse
What an animal is 13% dehydrated what are the physical exam findings
Plus or minus marked loss of skin turgor, obvious signs of shock.
How do you perform a skin turgor test
Twist the skin in between shoulder blades, the time it takes reflects the dehydration of the animal
What are some points to keep in mind when estimating the degree of dehydration
Aged animals lose their skin elasticity, patients with third space losses have no change in bodyweight: aka pleural effusion or ascites, obese patients or neonates can have abnormally resilient skin even when dehydrated, nausea and salivation moistens dry mucous membranes
What are the laboratory tests to test for dehydration
Packed cell volume, total protein, BUN, glucose, urine specific gravity, electrolytes, CBC, biochem
What are the three phases of fluid therapy
Emergency phase (hypovolemic shock) replacement phase (dehydration), maintenance phase (maintenance volume)
Describe shock
Ineffective perfusion of tissues with blood. Results in cellular hypoxia
What are the six signs of shock
Pale mucous membranes, increased capillary refill time, tachycardia, weak pulse, depression, cool extremities
What is hypovolemia
Decreased fluid volume within the intravenous space due to hemorrhage or trauma.
What happens when more than 25% of intravenous volume is lost
Severe hypovolemia and hypotension. This leads to hypovolemic shock
What happens when 50 to 60% of intravenous volume is lost
Cardiac arrest
What are some common causes of hypovolemia
Significant hemorrhage, loss of plasma water during severe vomiting or diarrhea, end-stage dehydration, inadequate intake, hypoproteinemia
What is the goal of the emergency phase
To reverse hypotension and shock, not to correct dehydration
What happens if the clinical signs of shock resolve after the first bolus of fluid
Proceed to replacement face if the animal is dehydration or the maintenance phase if he is not dehydrated but not eating or drinking
How do you tell if the clinical signs of hypovolemia are resolved
Mucous membrane color improves, heart rate decreases, pulse quality improves, attitude of animal improves, capillary refill time improves, respiratory rate stabilizes, peripheral extremities are warm
What volume of fluid is needed for dogs in the emergency phase
60 to 90 mL/kg/hr
What amount of fluid is needed for a cat in the emergency phase
45 to 60 mL/kg/hr
How do you calculate how many milliliters of fluid you need for the replacement phase
Deficit volume (hydration deficit), maintenance volume, abnormal ongoing losses volume
What is the deficit volume or the hydration deficit
Amount of fluid to be replaced to bring audible back to normal hydration status
What is maintenance fluid
The volume of fluid and amount of electrolytes that must be taken in on a daily basis to keep the volume of total body water and electrolyte content normal.
