Fluid Therapy Flashcards
Why do we give IV fluids during anesthesia/in general?
Encourage perfusion to major organs Promote blood flow to capillary beds Correct on-going losses Counteract hypotension/vasodilation Correct electrolyte or acid-base imbalances Means to administer intra-op drugs IV
What 3 compartments are body fluids divided into?
Intracellular fluid compartment (ICF)
Extracellular fluid compartment (ECF): intravascular and interstitial fluid compartments
What are the 4 types of pressures involved in Starling’s force?
- Capillary hydrostatic P
- Capillary oncotic P
- Interstitial hydrostatic P
- Interstitial oncotic P
* interstitial forces MUCH weaker
What are the guidelines of a pre-operative assessment for IV fluid tx?
- Clinical sx of dehydration and hypovolemia - skin tenting, dry mm, prolonged CRT, incr HR, cool extremeties, poor pulses
- PCV/TS, lactate, BUN & Creat, USG
- Co-morbidities affecting fluid admin - cardiac, renal, GI, and liver dz
What is the difference between dehydration and hypovolemia? What are the clinical signs for both of them?
Dehydration = loss of whole body water
Clin Sx: loss of skin turn or, dry MM, sunken eyes, severe: weak pulses, tachycardia, hypotension, obtunded
Hypovolemia = loss of fluids from the vascular compartment
Clin Sx: tachycardia, hypotension, weak pulses, prolonged CRT, cool extremities
What are the PE findings for a 5% dehydrated patient?
Minimal loss of skin turgor, dry MM, normal eye position
What are the PE findings for a 8% dehydrated patient?
Moderate loss of skin turgor, dry MM, threads pulses, sunken eyes, incr HR
What are the PE findings for a 10% dehydrated patient?
Considerable loss of skin turgor, severely sunken eyes, very dry mm, obtunded, incr HR, decr BP
If I weigh a blood-soaked gauze sponge I used for surgery in a patient and it weighed 2 g, approximately how much blood was absorbed in that sponge?
2 mL
Describe isotonic fluids. What are are few examples?
Electrolyte concentration very closely matches normal plasma levels
E.g. LRS, Plasmalyte 148, Normosol-R, 0.9% NaCl
T or F: Hypotonic fluids are used often for patients under anesthesia
False - rarely used
In what scenario would you use hypertonic fluids, such as hypertonic saline, for a patient?
If your patient needs very rapid volume expansion; used relatively often under anesthesia
What are crystalloids used for, and what is a disadvantage to using them?
Treating dehydration and short term fluid replacement
Disadvantage: leave intravascular fluid compartment rapidly
What are the uses of colloids, such as Hetastarch? Name some advantages and disadvantages
Uses: rapid volume expansion, oncotic support
Adv: dwell in IVF space
Disadv: volume overloading, coagulopathies, renal damage
What is the effect of giving fresh frozen plasma vs. whole blood and packed RBCs?
Plasma: colloid, volume expansion, oncotic support, clotting factors
Whole Blood/Packed Cells: volume expansion, incr O2 carrying capacity
What is the anesthetic maintenance fluid rate in dogs and horses vs. that in a cat?
5 mL/kg/hr (dogs, horses)
3 mL/kg/hr (cats) - less tolerant to fluid overloading
What are the general guidelines for an isotonic fluid therapy plan?
- Calculate fluid deficit, correct deficits prior to anesthesia by admin 1/4 dose and reassessing - admin remaining vol over 6-12 hrs
- Add maintenance requirement
- Add ongoing losses - estimate from sx hemorrhage, dieresis, GI losses and replace
How do you calculate a patient’s fluid deficit?
Fluid deficit (L) = body weight (kg) x % dehydration
What are the two main physiologic problems associated with hemorrhagic shock?
Hypovolemia and loss of O2 carrying capacity
What is the idea behind low volume resuscitation for hemorrhagic shock?
Prevent dilution of RBCs and clotting factors, avoids large incr in BP, improves patient outcome
What is a typical shock dose of isotonic crystalloids and how much should be administered in the case of hemorrhagic shock?
90/mL/kg; admin 1/4 to 1/3 of dose
What is the typical fluid treatment plan for hemorrhagic shock?
- ) 1/4-1/3 of shock dose of isotonic crystalloids
- ) 2-4 ml/kg of hypertonic fluid SLOWLY over 5 min - repeat as needed
- ) Admin 2-5 ml/kg bolus of colloid and repeat as needed UP TO total dose of 20 ml/kg/day
What are two ways to estimate blood loss in the case of hemorrhagic shock?
Weighing sponges and the volume in the suction canister
Each 2 mL/kg of whole blood will raise the PCV by what %?
1%
How will fluid administration for a patient in hemorrhagic shock differ whether that patient is compensating well or not?
If patient is decompensating —> GIVE RAPIDLY!
If patient is compensating —> give over MAX 4 hours
How do you calculate drip rates?
Body weight (kg) X maintenance rate (3 ml/kg/hr - cat; 5 ml/kg/hr - dog/horse) X whatever mL drip set you’re using
Approximate to 1 drop per however many seconds
What is the idea behind goal-directed fluid therapy?
Using surrogate markers of perfusion and cardiac output to guide fluid therapy
E.g. HR, BP, CVP, lactate, pulse pressure variation, urine output
Why do you need continuous IV access during an anesthetic procedure?
Provide fluid tx
Admin drugs
Transfusion tx
Anesthetic monitoring
= GOLD STANDARD of anesthetic care!
What is a commonly used alternative in horses for IV catheterization if you do not have access to the jugular?
Lateral thoracic vein
What site is the most commonly used for IVC in pigs?
The ear
What makes placing a jugular catheter in camelids difficult?
Their jugular grooves are very difficult to see/feel —> typically approaching blind
Be careful of the carotid!
Where would you place an IVC on a rabbit?
Marginal veins of the ears (be careful - their arteries are located in the center of the ear)
What are two common places intraosseous catheterization is performed?
Intertrochanteric fossa and the tibial crest
Why are intraosseous catheters in birds not placed in the humerus and femur?
Because they are pneumatic bones - use the ulna or tibiotarsus instead!
What are the uses for arterial catheterization? Possible complications?
Monitoring of continuous BP
Monitoring of resp gases
Gold standard monitoring in horses
Challenging to perform in small animals
Complications: hemorrhage/hematoma, air embolism, inadvertent injection of drugs
What are some possible complications of vascular access?
Vessel trauma Thrombophlebitis Catheter site infection Extravasation of fluids into SC tissues Air embolization Exsanguination Thrombosis (esp arterial access) Catheter breakage Hematoma Osteomyelitis (IO catheter)
